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Dairy Cows (dairy + cow)
Kinds of Dairy Cows Selected AbstractsSocio-Spatial Relationships in Dairy CowsETHOLOGY, Issue 1 2010Lorenz Gygax Farm animals may serve as models for evaluating social networks in a controlled environment. We used an automated system to track, at fine temporal and spatial resolution (once per minute, ±50 cm) every individual in six herds of dairy cows (Bos taurus). We then analysed the data using social network analyses. Relationships were based on non-random attachment and avoidance relationships in respect to synchronous use and distances observed in three different functional areas (activity, feeding and lying). We found that neither synchrony nor distance between cows was strongly predictable among the three functional areas. The emerging social networks were tightly knit for attachment relationships and less dense for avoidance relationships. These networks loosened up from the feeding and lying area to the activity area, and were less dense for relationships based on synchronicity than on median distance with respect to node degree, relative size of the largest cluster, density and diameter of the network. In addition, synchronicity was higher in dyads of dairy cows that had grown up together and shared their last dry period. This last effect disappeared with increasing herd size. Dairy herds can be characterized by one strongly clustered network including most of the herd members with many non-random attachment and avoidance relationships. Closely synchronous dyads were composed of cows with more intense previous contact. The automatic tracking of a large number of individuals proved promising in acquiring the data necessary for tackling social network analyses. [source] Serum Amyloid A and Haptoglobin Concentrations and Liver Fat Percentage in Lactating Dairy Cows with Abomasal DisplacementJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2010H. Guzelbektes Background: There has been increased interest in measuring the serum concentration of acute phase reactants such as serum amyloid A [SAA] and haptoglobin [haptoglobin] in periparturient cattle in order to provide a method for detecting the presence of inflammation or bacterial infection. Objectives: To determine whether [SAA] and [haptoglobin] are increased in cows with displaced abomasum as compared with healthy dairy cows. Animals: Fifty-four adult dairy cows in early lactation that had left displaced abomasum (LDA, n = 34), right displaced abomasum or abomasal volvulus (RDA/AV, n = 11), or were healthy on physical examination (control, n = 9). Materials and Methods: Inflammatory diseases or bacterial infections such as mastitis, metritis, or pneumonia were not clinically apparent in any animal. Jugular venous blood was obtained from all cows and analyzed. Liver samples were obtained by biopsy in cattle with abomasal displacement. Results: [SAA] and [haptoglobin] concentrations were increased in cows with LDA or RDA/AV as compared with healthy controls. Cows with displaced abomasum had mild to moderate hepatic lipidosis, based on liver fat percentages of 9.3 ± 5.3% (mean ± SD, LDA) and 10.8 ± 7.7% (RDA/AV). [SAA] and [haptoglobin] were most strongly associated with liver fat percentage, rs=+0.55 (P < .0001) and rs=+0.42 (P= .0041), respectively. Conclusions and Clinical Importance: An increase in [SAA] or [haptoglobin] in postparturient dairy cows with LDA or RDA/AV is not specific for inflammation or bacterial infection. An increase in [SAA] or [haptoglobin] may indicate the presence of hepatic lipidosis in cattle with abomasal displacement. [source] Review of Pododermatitis Circumscripta (Ulceration of the Sole) in Dairy CowsJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 4 2006Sarel R. van Amstel Sole ulcers are among the most frequent causes of lameness in dairy cattle. They are found most commonly in the hind lateral claw, are frequently bilateral, and have a high rate of reoccurrence. The pathogenesis of sole ulceration is primarily based on mechanical injury by the 3rd phalanx to the corium, basement membrane, and basal layers of the sole epidermis as a result of failure of the suspensory apparatus in the claw. The main pathways in the failure of the suspensory system include inflammatory (dermal vascular changes followed by disruption of keratinocyte proliferation and differentiation caused by local and systemic mediators) and noninflammatory (hormonal and biochemical changes in the peripartum period resulting in alterations of connective tissue in the suspensory system) pathways. Sole ulcers tend to occur in specific locations; the most reported site is the junction of the axial heel and sole. Other locations include the apex of the toe and the heel. Varying degrees of lameness may result, and the most severe are seen with complicated cases in which ascending infection affects the deeper structures of the claw. Pathologic changes at the ulcer site include dyskeratosis and dilated horn tubules with microcracks. Vascular changes include dilatation and thrombosis of capillaries with "neocapillary formation." Areas of dyskeratosis may remain for as long as 50 days at the ulcer site. Treatment includes corrective trimming and relief of weight bearing. Complicated cases may require surgical intervention. [source] Effects of a Progesterone-Based Oestrous Synchronization Protocol in 51- to 57-Day Postpartum High-Producing Dairy CowsREPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2010I Garcia-Ispierto Contents The aim of this study was to investigate the effect of applying a progesterone-based oestrous synchronization protocol at 51,57 days postpartum in high-producing dairy cows. The data analysed were derived from 1345 lactating cows. Cows between 51 and 57 days postpartum were assigned to the groups: control, PRID (receiving a progesterone-releasing intravaginal device for 9 days, and prostaglandin F2, 24 h before PRID removal) or GnRH,PRID (the same as the PRID group plus GnRH at PRID insertion). Oestrus was detected by using pedometers and confirmed by examination of the genital tract at AI. Oestrous and conception rates before days 71,77 postpartum, pregnancy loss in early pregnant cows or the cumulative conception rate registered on day 120 postpartum were considered as the dependent variables in four consecutive logistic regression analyses. Based on the odds ratios, the oestrous rate increased by a factor of 1.73 in cows showing oestrus before treatment for each unit increase in the number of previous oestruses; decreased by a factor of 0.44 in the control group with respect to the treatment groups; and by a factor of 0.61 in cows without luteal structures at treatment with respect to cows with corpora lutea. The conception rates of cows inseminated before days 71,77 postpartum remained similar across the groups, whereas the likelihood of pregnancy loss for cows becoming pregnant during this period was 0.11 times lower in the PRID group than in the control. Based on the odds ratio, the likelihood of a higher cumulative conception rate on day 120 postpartum: increased in cows showing oestrus before treatment by a factor of 1.41 for each unit increase in the number of previous oestruses, was reduced 0.56-fold in control cows compared with treated cows, and was also reduced by a factor of 0.98 for each kilogram of milk production increase recorded at treatment. In conclusion, although oestrous synchronization programmes performed in this study did not improve fertility, cows treated with progesterone could be inseminated earlier than untreated cows, such that the treatments increased the cumulative pregnancy rates determined on day 120 postpartum. In addition, fewer pregnancy losses were observed in early pregnant cows in the PRID group than the GnRH,PRID group. [source] First Service Pregnancy Rates Following Post-AI Use of hCG in Ovsynch and Heatsynch Programmes in Lactating Dairy CowsREPRODUCTION IN DOMESTIC ANIMALS, Issue 4 2010H Karami Shabankareh Contents Lactating dairy cows (n = 667) at random stages of the oestrous cycle were assigned to either ovsynch (O, n = 228), heatsynch (H, n = 252) or control (C, n = 187) groups. Cows in O and H groups received 100 ,g of GnRH agonist, i.m. (day 0) starting at 44 ± 3 days in milk (DIM), and 500 ,g of cloprostenol, i.m. (day 7). In O group, cows received 100 ,g of GnRH (day 9) and were artificially inseminated without oestrus detection 16,20 h later. In H group, cows received 1 mg oestradiol benzoate (EB) i.m., 24 h after the cloprostenol injection and were artificially inseminated without oestrus detection 48,52 h after the EB injection. Cows in C group were inseminated at natural oestrus. On the day of artificial insemination (AI), cows in all groups were assigned to subgroups as follows: human Chorionic Gonadotrophin (O-hCG) (n = 112), O-saline (n = 116), H-hCG (n = 123), H-saline (n = 129), C-hCG (n = 94) and C-saline (n = 93) subgroups. Cows in hCG and saline subgroups received 3000 IU hCG i.m. and or 10 ml saline at day 5 post-AI (day 15), respectively. Pregnancy status was assessed by palpation per rectum at days 40 to 45 after AI. The logistic regression model using just main effects of season (summer and winter), parity (primiparous and pluriparous), method1 (O, H and C) and method2 (hCG and saline) showed that all factors, except method1, were significant. Significant effects of season (p < 0.01), hCG and parity (p < 0.01), and a trend of parity and season (p < 0.1) were detected. A clear negative effect of warm period on first service pregnancy rate was noted (p < 0.01). The pregnancy rate was the lowest in the H protocol during warm period (p < 0.05). Treatment with hCG 5 days after AI significantly improved pregnancy rates in those cows that were treated with the H protocol compared with saline treatments (41.5% vs 24.8%; p < 0.01). O and H were more effective in primiparous than in pluriparous cows (46.1% vs 29.9%; p < 0.1 and 43.6% vs 24.6%; p < 0.01). First service pregnancy rates were higher in primiparous hCG-treated than in pluriparous hCG-treated cows (57.9% vs 32.3%; p < 0.01). The pregnancy rate was higher for the hCG-treated cows compared with saline-treated cows during warm period (37.9% vs 23.6%; p < 0.001). [source] Field Trial on Progesterone Cycles, Metabolic Profiles, Body Condition Score and their Relation to Fertility in Estonian Holstein Dairy CowsREPRODUCTION IN DOMESTIC ANIMALS, Issue 4 2008J Samarütel Contents Resumption of luteal activity postpartum and fertility were investigated in an Estonian Holstein high milk production and good fertility dairy herd. Body condition was scored after every 10 days in 54 multiparous dairy cows (71 lactations) calving inside from December to March during 4-year period. Blood samples were taken 1,14 days before calving and 1,14, 28,42 and 63,77 days after calving: analytes estimated were serum aspartate aminotransferase (AST), glucose, ketone bodies, total cholesterol, non-esterified fatty acids and triglycerides. The general linear mixed model was used to compare the data for cows with different characteristics in luteal activity postpartum based on their milk progesterone profiles. Forty-five per cent of cases had abnormal profiles; delayed resumption of ovarian cyclicity postpartum (DC) was the most prevalent abnormality. There was no difference in body condition scores between the groups. The DC and prolonged luteal phase groups had higher serum AST activity (p < 0.01) 1,14 days postpartum compared with normal group. The DC group also had higher cholesterol and triglyceride values (p < 0.05) 28,42 days postpartum and higher milk fat/protein ratio (p < 0.01) on the first month of lactation compared with normal profile group. Despite long post-calving anoestrous period (71 ± 5.0 days; mean ± SEM) DC group had 64.7% first service pregnancy rate (normal group 48.6% and PLP group 37.5%). This study did not find any detrimental effect of prolonged anovulatory period postpartum on subsequent fertility. [source] Effects of Clinical Mastitis on Ovarian Function in Post-partum Dairy CowsREPRODUCTION IN DOMESTIC ANIMALS, Issue 3 2005Gy Huszenicza Contents Mastitis-induced ovarian abnormalities were studied in a field trial. At 1,3 day after calving, ,2 parity cows not affected with chronic recurrent mastitis and yielding <400 000/ml somatic cell count (SCC) individual milk in the previous lactation, were enrolled in the study. Thereafter milk samples were collected three times weekly for 95,100 day for progesterone (P4) assay. Individual P4 profiles were used to monitor ovarian cyclicity. When mastitis was diagnosed in the first 80 day post-partum (pp), clinical signs were recorded and scored, and aseptic milk samples were taken to identify the mastitis pathogens. Depending on the isolated pathogens the cows were blocked into one of the three sub-groups affected by either Gram-positive (GP), or Gram-negative (GN) bacteria, or of those with no detected pathogens (NDP). Cows suffering from any type of mastitis between days 15 and 28 (n = 27) showed a delay in the onset of ovarian cyclicity, and estrus was postponed compared to cows affected during the first 14 day pp (n = 59) and controls (n = 175) (38.6 ± 2.3 vs 33.4 ± 2.1 and 32.0 ± 1.0 day, respectively, for onset of ovarian cyclicity and 90.7 ± 2.5 vs 80.2 ± 2.8 and 83.9 ± 2.1 day, respectively, for estrus; both p < 0.05). The percentage of cows ovulating by day 28 was lower in those affected by mastitis between days 14 and 28 compared to cows between days 1 and 14 and controls (22.2% vs 47.5 and 50.3%, respectively; p < 0.05). A significantly higher rate of premature luteolysis was observed in GN + NDP compared to GP mastitis and healthy cows (46.7% vs 8.3 and 2.0%, respectively; p < 0.001). If the mastitis outbreak occurred during the follicular phase, the duration of this cycle segment was lengthened in GN + NDP mastitis compared to GP mastitis and healthy cows (10.8 ± 0.9 vs 7.9 ± 0.1 and 7.2 ± 0.1, respectively; p < 0.001). The results indicate that mastitis can affect the resumption of ovarian activity in pp dairy cows. Mastitis may also impair reproduction also in cyclic cows: this effect can be the consequence of premature luteolysis or a prolonged follicular phase. [source] Dairy cows trapped between performance demands and adaptability,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2009Wilhelm Knaus Abstract The tremendous increase in the lactation performance of dairy cows during the last 60 years has had dramatic consequences on fertility and vitality (fitness) of the animals. Unprecedented average lactation performance levels have resulted in an equally unprecedented reduction in longevity. Economic pressure to further reduce the age at first calving is still high, although the negative correlation between precocious maturity and longevity is well documented in the relevant literature. Ever more aggressive selection and feeding measures are being taken to shorten the rearing time of heifers in order to reduce the cost of replacement heifers. An additional decrease in the stayability of cows has to be expected when the age at first calving is lowered even further. For reasons of profitability, dairy cows should complete an average of at least four lactations. Cows from the most important dairy breeds in the United States and Bavaria, Germany, already dropped below that crucial threshold many years ago. The same phenomenon has been observed in dairy cows in Austria over the past few years. Holstein cows that were culled in Austria in 2007 had an average of only 3.3 parities. To improve this situation, dairy cattle breeding programs should put a much higher emphasis on selection for traits of longevity and lifetime performance and, in return, markedly reduce the emphasis on selection for lactation performance in general and early-lactation performance test results in particular. Over millions of years of evolutionary adaptation, cattle have acquired the ability to utilize fibrous low-quality plant substrate. Only a strongly forage-based feeding regimen is, in the long run, in accordance with their digestive and metabolic configuration. The massive use of concentrates (mostly grain) in cattle rations increases the risk of digestive and metabolic disorders in cattle and consequently leads to impaired animal welfare. Finally, the careful management of scarce resources demands that a closer look be taken at the food balance in dairy rations, i.e., an awareness of how much food that is edible for humans is being fed to livestock. Copyright © 2009 Society of Chemical Industry [source] Transcutaneous ultrasound over the right flank to diagnose mid- to late-pregnancy in the dairy cowAUSTRALIAN VETERINARY JOURNAL, Issue 8 2009JC Hunnam Objective To investigate the practical application and image quality of transcutaneous ultrasonography across the right flank for the diagnosis of mid- to late-gestation in cattle. Procedure Dairy cows of known pregnancy status were used to establish criteria for the identification of mid- to late-stage pregnancy by transcutaneous ultrasonography. Factors involved in the practical application of transcutaneous ultrasound for routine use in pregnancy diagnosis in dairy cattle were also examined. Results Transcutaneous ultrasound, using a 3.5-MHz sector transducer applied over the caudodorsal right flank fold, allowed rapid and detailed visualisation of bovine pregnancy (i.e. fetus, fetal fluids, placentomes and/or fetal membranes) and could be used to establish criteria for the diagnosis of pregnancy. The commonly available cattle holding facilities of the herringbone dairy, rotary herringbone dairy, AI race or crush, and walk-through dairy all allow safe access to the right flank of a dairy or beef cow. However, transcutaneous scanning over the right flank is difficult in modern rotary turnstile dairies. Conclusion A 3.5-MHz sector transducer applied over the caudodorsal right flank fold allows detailed visualisation of the bovine fetus in most types of cattle-holding facilities. Further investigation of the sensitivity and specificity of this technique over the entire gestation period and its possible use in ageing of the bovine fetus is merited. [source] The influence of strain of Holstein-Friesian dairy cow and pasture-based feeding system on grazing behaviour, intake and milk productionGRASS & FORAGE SCIENCE, Issue 1 2007S. McCarthy Abstract A comparative study of grazing behaviour, herbage intake and milk production of three strains of Holstein-Friesian dairy cow was conducted using three grass-based feeding systems over two years. The three strains of Holstein-Friesian cows were: high production North American (HP), high durability North American (HD) and New Zealand (NZ). The three grass-based feeding systems were: high grass allowance (MP), high concentrate (HC) and high stocking rate (HS). In each year seventy-two pluriparous cows, divided equally between strains of Holstein-Friesian and feeding systems were used. Strain of Holstein-Friesian cow and feeding system had significant effects on grazing behaviour, dry matter (DM) intake and milk production. The NZ strain had the longest grazing time while the HD strain had the shortest. The grazing time of cows in the HC system was shorter than those in both the HS and MP systems. There was a significant strain of Holstein-Friesian cow by feeding system interaction for DM intake of grass herbage and milk production. The NZ strain had the highest substitution rate with the HP strain having the lowest. Hence, response in milk production to concentrate was much greater with the HP than the NZ strain. Reduction in milk yield as a consequence of a higher stocking rate (MP vs. HS system) was, however, greater for the HP and HD strains compared with the NZ strain. The results suggest that differences in grazing behaviour are important in influencing DM intake and milk production. [source] Estimates of the efficiency of transfer of L -histidine from blood to milk when it is the first-limiting amino acid for secretion of milk protein in the dairy cowJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2001Chang-Hyun Kim Abstract The efficiency of transfer of L -histidine into milk protein was measured in two experiments in which L -histidine was infused intravenously into dairy cows eating a basal diet of grass silage and a cereal-based supplement containing feather meal. Both experiments used Latin square designs, and infusion periods lasted 10 days. In Experiment 1, histidine was infused alone at doses of 3, 6 and 9,g,day,1. The output of milk protein increased up to the 6,g,day,1 dose but fell back to the basal level when 9,g,day,1 was infused. The efficiency of transfer was highest for the 6,g,day,1 dose, for which the value was 0.38. In Experiment 2 the same three histidine doses as in Experiment 1 were used, but this time the histidine was accompanied by 8,g L -methionine, 28,g L -lysine and 2.5,g L -tryptophan, to ensure that histidine remained first-limiting over the whole dose range. The output of histidine in milk protein (Y) increased linearly with histidine dose (X) such that Y,,=,0.431 X,+,0.070 r,,=,0.998; n,,=,4, indicating an efficiency of transfer of 0.43. © 2001 Society of Chemical Industry [source] Sequence variants in the bovine gonadotrophin releasing hormone receptor gene and their associations with fertilityANIMAL GENETICS, Issue 3 2010K. Derecka Summary Seven sequence variants (SVs) have been identified in exon 1 and in the promoter region upstream of the bovine gonadotrophin releasing hormone (GnRH) receptor gene, at nucleotides g.,331A>G, g.,108T>C, g.+206G>A, g.+260C>T, g.+341C>T, g.+383C>T and g.+410C>T relative to the translation start site. The SVs at nucleotides g.,108, g.260, g.341 and g.410 and those at g.206 and g.383 formed two groups with complete linkage disequilibrium within groups, but incomplete linkage disequilibrium between groups, and none of the SVs altered receptor amino acid sequence. The g.,108T>C allelic variants were associated with an approximately 0.4 day reduction in predicted transmitting ability for days to first service. None of the allelic variants affected the pattern of circulating LH following administration of GnRH. The g.260C>T alteration introduced a new transcription factor binding site in a region of DNA with relatively low nucleosome formation potential. The data suggest that selection for animals carrying the g.-108T>C group of alterations will improve fertility in the dairy cow. [source] The somatotropic axis of the dairy cow revisitedANIMAL SCIENCE JOURNAL, Issue 1 2002Michael Terence ROSE ABSTRACT The greater understanding of the somatotropic axis in the lactating dairy cow that has been achieved in recent years is briefly reviewed in this article. Specifically discussed are: the significance of multiple forms of insulin-like growth factor messenger RNA (ribonucleic acid) caused by alternative splicing, and the possible functions of the various translated extension proteins; the possible roles of multiple sites of growth hormone secretion other than in the pituitary, and the implications for possible autocrine or paracrine growth hormone secretion; the consequences for increased circulating growth hormone half-life, and possibly biological effectiveness, caused by growth hormone binding proteins; and the increasing evidence for the presence of growth hormone receptors in the bovine mammary gland. The need for further research is highlighted in the present review; published information regarding the bovine, in many of these areas, is still largely insufficient. [source] Association between gestational age and bovine fetal characteristics measured by transcutaneous ultrasound over the right flank of the dairy cowAUSTRALIAN VETERINARY JOURNAL, Issue 9 2009JC Hunnam Objective To determine bovine fetal characteristics significantly associated with increasing gestational age as measured via transcutaneous ultrasonography over the right flank. Methods The length of gestation at date of pregnancy diagnosis via transcutaneous and transrectal ultrasonography was determined for 224 dairy cattle by estimation from subsequent calving dates. A separate dataset was created for each measurable fetal characteristic (i.e. thoracic diameter, abdominal diameter, umbilical diameter, placentome length and placentome height) and risk factors significantly associated with gestational age at pregnancy diagnosis within each dataset, including the fetal characteristic, were identified. Results Abdominal diameter was the most frequently observed fetal characteristic and thoracic diameter was the least. Gestational age at pregnancy diagnosis (d) was significantly associated with fetal thoracic diameter (P < 0.01), abdominal diameter (P < 0.01) and umbilical diameter (P = 0.02) when measured via transcutaneous ultrasound. Within each model, sire breed, dam breed, dam age and/or calf sex were also significantly associated with gestational age. Gestational age at pregnancy diagnosis was not significantly associated with either placentome height or length (P > 0.05). Conclusion Fetal thoracic diameter, abdominal diameter and umbilical diameter were found to be significantly associated with gestational age between approximate days 73 to 190 of gestation. Transcutaneous ultrasonography may prove a useful method of estimating gestational age in the absence of accurate breeding records. [source] Transcutaneous ultrasound over the right flank to diagnose mid- to late-pregnancy in the dairy cowAUSTRALIAN VETERINARY JOURNAL, Issue 8 2009JC Hunnam Objective To investigate the practical application and image quality of transcutaneous ultrasonography across the right flank for the diagnosis of mid- to late-gestation in cattle. Procedure Dairy cows of known pregnancy status were used to establish criteria for the identification of mid- to late-stage pregnancy by transcutaneous ultrasonography. Factors involved in the practical application of transcutaneous ultrasound for routine use in pregnancy diagnosis in dairy cattle were also examined. Results Transcutaneous ultrasound, using a 3.5-MHz sector transducer applied over the caudodorsal right flank fold, allowed rapid and detailed visualisation of bovine pregnancy (i.e. fetus, fetal fluids, placentomes and/or fetal membranes) and could be used to establish criteria for the diagnosis of pregnancy. The commonly available cattle holding facilities of the herringbone dairy, rotary herringbone dairy, AI race or crush, and walk-through dairy all allow safe access to the right flank of a dairy or beef cow. However, transcutaneous scanning over the right flank is difficult in modern rotary turnstile dairies. Conclusion A 3.5-MHz sector transducer applied over the caudodorsal right flank fold allows detailed visualisation of the bovine fetus in most types of cattle-holding facilities. Further investigation of the sensitivity and specificity of this technique over the entire gestation period and its possible use in ageing of the bovine fetus is merited. [source] Comparison of transcutaneous ultrasound over the right flank with transrectal ultrasound for pregnancy diagnosis in the dairy cowAUSTRALIAN VETERINARY JOURNAL, Issue 8 2009JC Hunnam Objective Evaluate the sensitivity and specificity of transrectal ultrasound and transcutaneous ultrasonography across the right flank between days 31 and 196 of pregnancy in the dairy cow. Procedure Pregnancy status and stage of gestation at date of pregnancy diagnosis by transcutaneous and transrectal ultrasonography were determined for 1570 dairy cattle. Sensitivity and specificity values and probabilities of a correct diagnosis for both techniques were determined and compared. Possible effects of gestational age, herd, method of transcutaneous ultrasound diagnosis, cow age, cow and bull breed, and calf sex on the determination of a correct diagnosis of pregnancy status were evaluated for both techniques. Results The overall sensitivity and probability of a correct diagnosis of pregnancy status from days 31 to 196 of gestation were significantly higher when using transrectal ultrasound relative to transcutaneous ultrasound over the right flank. However, the sensitivity of transcutaneous ultrasound changed over the course of pregnancy: it was low (7,8%) before day 84, increased to 89% between days 141 and 154, and was close to 100% thereafter. The specificity of both methods did not differ significantly. Herd and gestational age at date of pregnancy diagnosis were significantly associated with making a correct test result using transcutaneous ultrasound, although only the latter predictor was significantly associated with making a correct test result using transrectal ultrasound. Conclusion Transcutaneous ultrasound can not be recommended as an accurate method for early pregnancy diagnosis in the dairy cow, particularly on a whole-herd basis. However, if pregnancy testing is undertaken in mid to late gestation, this technique could provide an accurate and rapid alternative to transrectal ultrasound or manual palpation per rectum. [source] Mycotic pneumonia in a dairy cow caused by Mortierella wolfiiAUSTRALIAN VETERINARY JOURNAL, Issue 7 2003LJ GABOR No abstract is available for this article. [source] Socio-Spatial Relationships in Dairy CowsETHOLOGY, Issue 1 2010Lorenz Gygax Farm animals may serve as models for evaluating social networks in a controlled environment. We used an automated system to track, at fine temporal and spatial resolution (once per minute, ±50 cm) every individual in six herds of dairy cows (Bos taurus). We then analysed the data using social network analyses. Relationships were based on non-random attachment and avoidance relationships in respect to synchronous use and distances observed in three different functional areas (activity, feeding and lying). We found that neither synchrony nor distance between cows was strongly predictable among the three functional areas. The emerging social networks were tightly knit for attachment relationships and less dense for avoidance relationships. These networks loosened up from the feeding and lying area to the activity area, and were less dense for relationships based on synchronicity than on median distance with respect to node degree, relative size of the largest cluster, density and diameter of the network. In addition, synchronicity was higher in dyads of dairy cows that had grown up together and shared their last dry period. This last effect disappeared with increasing herd size. Dairy herds can be characterized by one strongly clustered network including most of the herd members with many non-random attachment and avoidance relationships. Closely synchronous dyads were composed of cows with more intense previous contact. The automatic tracking of a large number of individuals proved promising in acquiring the data necessary for tackling social network analyses. [source] Fatty acid ruminal metabolism and digestibility in cows fed perennial ryegrassEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 8 2007Michel Doreau Abstract The ruminal metabolism and intestinal digestibility of fatty acids (FA) was studied in four mid-lactation dairy cows fitted with ruminal and duodenal cannulae. The cows received fresh perennial ryegrass as sole feed. Two grasses were compared, differing in the soluble carbohydrate/nitrogen ratio (SC+/N, and SC,/N+ ratios). This ratio was modified by the combination of three factors: age of regrowth, N,fertilisation and hour of cutting. The two grasses contained 12.5 and 20.7% of crude protein, and 24.6 and 13.7% of SC, respectively. The SC+/N, grass contained less FA [1.82 vs. 2.49% of dry matter (DM)] and a lower percentage of linolenic acid (60.9 vs. 65.6% of FA). As DM intake did not differ between treatments, FA intake was higher for the SC,/N+ treatment. The duodenal composition of FA revealed numerous isomers of 18:1 and conjugated and non-conjugated isomers of 18:2. SC,/N+ treatment resulted in a higher duodenal flow of stearic, linoleic, and linolenic acids and of several intermediates of linolenic acid hydrogenation. This was a consequence of differences in intake. Intestinal digestibility of FA from both grasses was high (around 90%). The proportions of FA in plasma did not reflect with accuracy the differences in duodenal FA resulting from differences in ruminal metabolism. [source] Effect of frequency of application of inorganic nitrogen fertilizer within a rotational paddock-grazing system on the performance of dairy cows and inputs of labourGRASS & FORAGE SCIENCE, Issue 2 2008C. P. Ferris Abstract As herd sizes and labour costs increase, and the availability of skilled labour decreases, efficient use of available labour becomes more important in dairy cow systems. Two experiments were conducted to examine the effect of reducing the frequency of application of inorganic nitrogen (N) fertilizer on inputs of labour and performance of dairy cows. Experiments 1 (duration of 169 d) and 2 (duration of 179 d) involved fifty-eight and forty multiparous Holstein,Friesian dairy cows, respectively, in mid-lactation. In each experiment, in the ,infrequent' treatment fertilizer was applied to all paddocks on a single occasion at the start of each grazing cycle, while in treatment ,frequent', fertilizer was applied on three occasions each week, within 2 or 3 d of each paddock having been grazed. The experimental treatments were started from 30 March and 29 March in Experiments 1 and 2 respectively. Total N application rates were approximately 360 and 250 kg N ha,1 in Experiments 1 and 2 respectively. Concentrate feed (4·0 kg per cow) was offered daily in both experiments. With the ,infrequent' treatment, highest concentrations of crude protein and nitrate in herbage were observed in swards grazed approximately 10 d after N fertilizer was applied. Treatment had no significant effect on milk yield, milk fat and protein concentrations, and final live weight and body condition score of cows in either experiment. Milk urea and plasma urea concentrations were not significantly affected by treatment. Calculated application times of fertilizer for a herd of 100 dairy cows were 107 and 83 min week,1 for the ,frequent' and ,infrequent' treatments respectively. [source] Dietary cation,anion difference and cadmium concentration in grasses fertilized with chlorideGRASS & FORAGE SCIENCE, Issue 4 2007S. Pelletier Abstract High dietary cation,anion difference (DCAD) of grass herbage increases the occurrence of hypocalcaemia of dairy cows. Application of chloride fertilizer reduces DCAD of herbage but it could increase cadmium concentration in herbage. This study includes an experiment conducted in Australia and in Canada. A glasshouse experiment in Australia evaluated the effect of four rates of chloride application (0,240 kg ha,1) on values of herbage DCAD and cadmium concentration of above-ground plant material of timothy (Phleum pratense L.) and phalaris (Phalaris aquatica L.), harvested 6 weeks after sowing and grown on two soils that had received cadmium either as a contaminant in superphosphate (soil + Super) or in sewage biosolids (soil + Bio) along with respective control soils (soil 0 Super and soil 0 Bio). Application of chloride fertilizer decreased values of herbage DCAD by 349 mmolc kg,1 dry matter (DM). Herbage DCAD values were highest on the 0 Bio soil (739 mmolc kg,1 DM) and were not different among the three other soils. Species did not differ in herbage DCAD values. Cadmium concentration in the above-ground plant material was highest on the +Bio soil treatment (1·67 mg kg,1 DM) and was lower for the three other soil treatments. Above-ground plant material of phalaris had a higher cadmium concentration than that of timothy. Application of chloride fertilizer did not affect cadmium concentration in above-ground plant material, despite the high cadmium content of the soil on the +Bio treatment. The field experiment in Canada evaluated the effect of four rates of chloride application (0,144 kg ha,1) on cadmium concentration of a timothy-based grass sward grown on four sites with soils of different potassium content. Application of chloride fertilizer increased cadmium concentration of herbage at two of the four sites but the maximum increase in cadmium concentration was only 0·025 mg kg,1 DM. Chloride fertilizer can be applied to decrease forage DCAD with minimal risk of increasing Cd in the food chain. [source] Production and behavioural responses of high- and low-yielding dairy cows to different periods of access to grazing or to a maize silage and soyabean meal diet fed indoorsGRASS & FORAGE SCIENCE, Issue 4 2006O. Hernandez-Mendo Abstract The study examined whether high-yielding cows grazing pasture respond differently from low-yielding cows in milk production and feeding behaviour, to increasing the time made available for eating a maize silage and soyabean meal (TAMS) diet indoors and reducing the time available for grazing (TAG). Two experiments, each lasting 42 d, were carried out in spring (Experiment 1) and autumn (Experiment 2) using Holstein-Friesian cows at two different levels of milk yield (MYL). Milk production and feeding behaviour were examined for TAG + TAMS systems of 19 h, TAG plus 1 h TAMS (19 + 1), and 5 h TAG plus 15 h TAMS (5 + 15). There were two levels of concentrate (0 and 6 kg d,1), and in the spring experiment two sward heights (4,6 and 8,10 cm) were also studied. Milk yield, persistency of milk yield, liveweight change and estimated total DM intake were significantly higher on the 5 + 15 than on the 19 + 1 grazing system in Experiment 1 but not in Experiment 2. There were no significant interactions of TAG + TAMS treatment with MYL for any production or behavioural measurements except for maize silage feeding time, where high MYL cows spent a significantly greater time eating maize silage than low MYL cows on the 5 + 15 treatment but not on the 19 + 1 treatment. It can be concluded that high- and low-yielding cows respond similarly in milk production and feeding behaviour to different combinations of TAG and TAMS. In autumn, estimated daily intakes of herbage were lower on both grazing treatments relative to spring, resulting from lower rates of herbage intake with no compensatory increase in grazing time. In contrast, rates of intake of maize silage were higher in autumn especially on the 19 + 1 system. These results may imply a change of preference from herbage to maize silage between spring and autumn. [source] Release of cell contents and comminution of particles of perennial ryegrass herbage during ingestion by dairy cows fed indoors or grazingGRASS & FORAGE SCIENCE, Issue 3 2006A. Boudon Abstract The effect of feeding indoors fresh perennial ryegrass vs. grazing on ingestive behaviour, release of cell contents and comminution of particles during ingestion, as well as on gas production of ingested boli fermented in vitro, was studied. Indoor feeding and grazing were compared using four dairy cows according to a triple reversal design with six periods. Chemical and morphological composition of the ingested herbage was similar for both indoor feeding and grazing treatments. The intake rate was markedly higher indoors compared with grazing [52·1 vs. 22·9 g dry matter (DM) min,1] with heavier boli and less saliva added per gram of DM intake. The proportions of intracellular nitrogen and chlorophyll released during mastication after ingestion of herbage fed indoors were lower, and the median size of the particles in the boli was larger (5·97 vs. 4·44 mm) compared with grazing. As a result, the rate of gas production in vitro was also lower for herbage fed indoors compared with grazing (0·423 vs. 0·469 mL min,1 g,1 incubated DM). Indoor feeding or grazing may have limited consequences in vivo on the kinetics of availability of nutrients for micro-organisms in the rumen, because the consequences of the more extensive physical damage suffered by herbage ingested at grazing could be compensated by a lower intake rate. [source] Effects of grass pasture and concentrate-based feeding systems for spring-calving dairy cows in early spring on performance during lactationGRASS & FORAGE SCIENCE, Issue 3 2005E. Kennedy Abstract The effect of offering a total mixed ration of silage and concentrate (proportionately 0·44 silage) system [indoor feeding system (IF)] was compared with grazing at a high daily herbage allowance with a low level of concentrate supplementation [early grazing system (EG)] in early spring on the performance of spring-calving dairy cows in Ireland. Sixty-four spring-calving Holstein,Friesian dairy cows (mean calving date, 2 February) were allocated to one of two systems between 16 February and 4 April 2004. An equal number of primiparous and multiparous cows were assigned to each system. The dairy cows on the IF system were housed for a 7-week period and offered a diet of 10·9 kg DM cow,1 d,1 (s.d. 2·3) of concentrate, the remainder of the diet was 8·6 kg DM cow,1 d,1 (s.d. 1·9) of grass silage. The dairy cows on the EG system were offered a mean daily herbage allowance of 15·1 kg DM cow,1 d,1 (s.d. 3·7) and were supplemented with 3·0 kg DM cow,1 d,1 (s.d. 1·0) of concentrate. There was no difference in milk yield between the two systems but the cows in the EG system had a higher milk protein concentration (2·9 g kg,1) and a higher milk protein yield than in the IF system. Milk fat concentration was higher for cows in the IF than EG system (3·0 g kg,1). There was no difference in total daily dry-matter intake between the systems, measured in week 6 of the study. Mean live weight of the cows in the IF system was greater than in the EG system. The results of the study suggest that a slightly greater performance can be achieved by a system offering a high daily herbage allowance to spring-calving dairy cows in early lactation compared with a system offering a total mixed ration containing a high proportion of concentrate with grass silage. [source] The influence of sward canopy structure on foraging decisions by grazing cattle.GRASS & FORAGE SCIENCE, Issue 2 2003Abstract Patch selection by grazing dairy cows in response to simultaneous variation in combinations of sward structural characteristics was examined in three experiments in which four mature dairy cows were offered a choice of patches (typically 0.9 m × 0.9 m) of perennial ryegrass (Lolium perenne) presented in a linear arrangement. Treatments involved combinations of variations in sward height, stubble height and/or depth of regrowth, prepared by preliminary cutting treatments. They were arranged in balanced sets of four to nine treatments, which were arranged in linear sequences of eighteen to twenty-seven patches. Within experiments, sequences were balanced across replicate sets of patches, which were grazed separately by individual cows. The number of bites removed and the residence time for each patch were highly correlated in all three experiments, and the results are reported using number of bites per patch as an estimator of foraging behaviour. In the first experiment, with vegetative swards, cows preferentially selected the tallest swards. When swards comprising reproductive stem were offered in Experiment 2, cows selectively grazed short-stubble swards rather than tall-stubble swards, although both offered a similar depth of regrowth. Cows did not exhibit preference for swards comprising the greatest quantity of leaf mass, indicating that the spatial distribution of plant components assumed greater importance. In the third experiment, the number of bites removed increased with increasing depth of regrowth, and was negatively correlated with sward height. The three patch-appraisal cues investigated were broadly ranked in order of importance as (i) depth of regrowth, (ii) sward maturity and (iii) sward height. There was no evidence, at least at a short temporal scale, that patch behaviour was influenced by conditions in adjacent patches, suggesting that the cows assessed grazing opportunities on a patch-by-patch basis. [source] The effect of sward structure as influenced by ryegrass genotype on bite dimensions and short-term intake rate by dairy cowsGRASS & FORAGE SCIENCE, Issue 1 2003P. D. Barrett Abstract The effects of genotypic variation in ryegrasses on sward structure, bite dimensions and intake rate by dairy cows were investigated. Two experiments were conducted. In Experiment 1, swards were in a vegetative state whereas, in Experiment 2, they were partly reproductive and were taller with higher herbage mass but lower leaf proportion than in Experiment 1. Applicability of relationships between sward structure and bite characteristics, previously established from artificial or hand-constructed swards, to field conditions were tested. Additional short-term intake rates and/or sward structural characteristics were considered as indicators of potential intake for use in protocols for the evaluation of grass varieties. Four cultivars were studied: AberElan, Twins (diploid and tetraploid perennial ryegrasses respectively), Polly, a hybrid ryegrass (perennial × Italian ryegrass) and Multimo (Italian ryegrass), each established in 200-m2 plots in four replicated blocks. Herbage intake rate was determined by short-term liveweight change (taking account of insensible weight loss) using 16 dairy cows allocated to four balanced groups with each plot grazed by one group for a 1-h assessment period. One block was grazed per day, over a 4-d experimental period, with each group grazing each variety in a complete crossover design. Sward characteristics and bite rate were also measured in both experiments. Bite dimensions were subsequently estimated, with bite depth being determined as a function of extended tiller height (ETH) in both experiments. Within both experiments, bite mass and intake rate did not differ significantly between swards of different cultivars despite swards containing Multimo generally having a higher ETH and water-soluble carbohydrate concentration and lower green leaf mass, sward bulk density and neutral-detergent fibre concentration than the other swards. However, bite depth was significantly higher (P < 0·01) in swards containing Multimo swards than in the others and, in Experiment 1, bite depth, as a proportion of ETH, was higher in swards containing Multimo and lower in those containing Twins than in the other two cultivars, whereas there was no difference in Experiment 2. Taking both experiments together, the mean bite depth was 0·5 of ETH with sward bulk density accounting for almost half the variance in the relationship between bite depth and ETH. The bulk density of the bite (bite mass per unit bite volume), measured in Experiment 2, followed a similar pattern to sward bulk density, increasing in the order Multimo, Polly, AberElan and Twins. It is concluded that the relationships between sward characteristics and bite dimensions, derived from artificial swards, are applicable to field swards, although the range in natural ryegrass sward characteristics is usually not as wide as in experiments using artificial swards. Lack of precision in the measurement of short-term intake and in sward-based measurements is likely to preclude their use in the evaluation of grass varieties. [source] The effect of forage type and level of concentrate supplementation on the performance of spring-calving dairy cows in early lactationGRASS & FORAGE SCIENCE, Issue 3 2002P. Dillon Abstract In 1993 and 1994, 40 cows in early lactation in early spring were assigned randomly to four feeding treatments. One group of cows was kept indoors with access to grass silage ad libitum, plus 6 kg of concentrate daily. The other three groups had access to grass pasture (5,6 h per day in 1993 and 11,12 h per day in 1994) plus grass silage similar to that fed to the previous group while indoors plus 6, 4 or 2 kg of concentrate daily. The average daily allocations of herbage (> 3·5 cm) were 8·5 and 14·0 kg DM cow,1 day,1 in 1993 and 1994 respectively. The treatments were applied for 8 weeks (26 February to 23 April) in 1993, and 7 weeks (11 March to 29 April) in 1994. Cows with access to pasture had lower (P < 0·001) silage dry-matter (DM) intakes and higher (P < 0·001) total forage DM intakes in both years than those kept indoors. This resulted in significantly higher yields of milk, fat, protein and lactose. Similarly, milk protein concentration was higher (P < 0·05 in 1993; P < 0·001 in 1994). There was a significant linear increase in total DM intake in both years with increased concentrate supplementation. In 1993, there was a linear increase in milk (P < 0·01), fat (P < 0·01), protein (P < 0·001) and lactose (P < 0·01) yields with increased concentrate supplementation. In 1994, only milk protein yield (P < 0·05) was increased. Concentrate supplementation had no effect on milk composition or liveweight change. Cows with access to grazed grass had higher liveweight gains (P < 0·05) than those kept indoors in both years. In 1993, increasing the energy intake increased the processing qualities of the milk produced. The results showed that access to grass pasture resulted in higher milk production, in reduced silage requirement and in reduced level of concentrate supplementation required for a given level of milk production with spring-calving cows in early lactation compared with those kept indoors. [source] Setting management limits for the production and utilization of herbage for out-of-season grazingGRASS & FORAGE SCIENCE, Issue 1 2000Laidlaw Three experiments were carried out on perennial ryegrass-dominant swards to provide a basis for recommendations for the limits to (a) building up and timing of utilization of a herbage ,bank' for out-of-season grazing and (b) duration and intensity of early spring grazing in the United Kingdom and Ireland. In experiment 1, the effect of regrowth interval (from 7 September, 20 October, 17 November or 15 December) in autumn on herbage accumulation, leaf turnover and on subsequent spring growth was investigated. Swards regrown from early September reached maximum herbage mass (about 3 t ha,1 DM) and leaf lamina content in mid-November, by which time senescence rate exceeded rate of production of new leaves. New leaf production and senescence rates were greater in swards remaining uncut until December than in those cut in October or November. Time of defoliation up to December had no effect on spring herbage mass in the subsequent spring. Defoliating in March reduced herbage mass in late May by less than 20%. Experiment 2 investigated the progress in herbage growth and senescence in swards regrowing from different times in late summer and autumn to produce herbage for utilization beyond the normal grazing season. Treatments in a randomized block design with three replicates were regrowths from 19 July, 8 August, 30 August and 20 September. Based on a lower ceiling of leaf and total herbage mass being reached with progressively later regrowths, beyond which leaf senescence generally exceeded leaf production and herbage mass declined, it was concluded that currently recommended rotation lengths for this period should extend from 3 weeks in late July to 8 weeks for swards previously grazed in mid-September. In both experiments, leaf senescence commenced earlier (by one leaf-age category) than previously published estimates and so brought forward the time at which senescence rates balanced leaf growth rates. In experiment 3, designed to evaluate the effect of daily grazing period and intensity in early spring on herbage regrowth, dairy cows grazed successive plots (replicates) for 2 or 4 h each day at two intensities (target residual heights of 5 or 7 cm) in March to mid-April. Regrowth rate was similar in all treatments including the ungrazed control, despite soil moisture content being relatively high on occasions. Tiller density was significantly reduced in May by grazing plots in early or mid-April. It is concluded that in autumn there are limits to which rotation lengths should be extended to produce herbage for out-of-season grazing owing to attainment of ceiling yields. Although utilization in early spring may reduce herbage availability in spring, out-of-season utilization need not reduce herbage growth rates in early spring. [source] Household-level Impacts of Dairy Cow Ownership in Coastal KenyaJOURNAL OF AGRICULTURAL ECONOMICS, Issue 2 2004Charles F. Nicholson This study uses heteroskedastic Tobit and Censored Least Absolute Deviations models to examine the impacts of dairy cow ownership on selected outcomes for a sample of 184 households in coastal Kenya. The outcomes examined include gross household cash income, gross non-agricultural income, consumption of dairy products, time allocated to cattle-related tasks, number of labourers hired and total wage payments to hired labourers. The number of dairy cows owned has a large and statistically significant impact on household cash income; each cow owned increased income by at least 53% of the mean total income of households without dairy cows. Dairy cow ownership also increases consumption of dairy products by 1.0 litre per week, even though most of the increase in milk production is sold. The number of dairy cows has no significant effect on total labour for cattle-related tasks. However, in contrast to previous studies, labour allocation to cattle by household members decreases and labour requirements for dairy cows are met primarily by an increase in hired labour. Dairy cow ownership results in relatively modest increases in payments to hired labourers and the number of hired labourers employed. The large positive impacts on income and the substitution of hired for household labour in cattle care suggest that intensification of smallholder dairying can be beneficial as a development strategy in the region if disease and feed constraints are addressed. [source] Estimates of genetic parameters for Boran, Friesian, and crosses of Friesian and Jersey with the Boran cattle in the tropical highlands of Ethiopia: milk production traits and cow weightJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 3 2004S. Demeke Summary Breed additive and non-additive effects plus heritabilities and repeatabilities for milk yield per lactation (LMY), milk yield per day (DMY), lactation length (LL), annual milk yield (AMY), annual milk yield per metabolic body weight (AMYBW) and cow weight at calving (BW) were estimated for 5464 lactation records collected from purebred Boran (B), Friesian (F), and crosses of Friesian and Jersey (J) breeds with the Boran breed raised in the tropical highlands of Ethiopia. Single trait analysis was carried out by using two equivalent repeatability animal models. In the first model the genotype was fitted as a fixed group effect, while in the second model the genotype was substituted by breed additive, heterotic and recombination effects fitted as fixed covariates. Both the F and J breed additive effects, measured as a deviation from the B breed were significant (p < 0.01) for all traits, except for BW of the J. The F and J additive contributions were 2774 ± 81 and 1473 ± 362 kg for LMY, 7.1 ± 0.2 and 4.8 ± 0.8 kg for DMY, 152 ± 7 and 146 ± 31 days for LL, 2345 ± 71 and 1238 ± 319 kg for AMY, 20.6 ± 0.9 and 18.9 ± 4.3 kg for AMYBW, and 140 ± 4 and ,21 ± 22 kg (p > 0.05) for BW. The heterotic contributions to the crossbred performance were also positive and significant (p < 0.01) for all traits. The F1 heterosis expressed as a deviation from the mid-parent values were 22 and 66% for LMY, 11 and 20% for DMY, 29 and 29% for LL, 21 and 64% for AMY, 42 and 42% for AMYBW, and 2% (p < 0.05) and 11% for BW for the F × B and J × B crosses, respectively. The recombination effect estimated for the F × B crosses was negative and significant for LMY (,526 ± 192 kg, p < 0.01), DMY (,3.0 ± 0.4 kg, p < 0.001), AMY (,349 ± 174 kg, p < 0.05) and BW (,68 ± 11 kg, p < 0.001). For the J × B crosses the recombination loss was significant and negative only for DMY (,2.2 ± 0.7 kg, p < 0.05) and BW (,33 ± 17 kg, p < 0.05). The direct heritabilities (h2) estimated for LMY, DMY, LL, AMY and AMYBW were 0.24 ± 0.04, 0.19 ± 0.03, 0.13 ± 0.03, 0.23 ± 0.04 and 0.17 ± 0.05, respectively. Based on the genetic parameters estimated, the best breeding strategy to increased milk production under highland Ethiopian conditions is to apply selection on purebred base populations (Boran and Friesian) and then crossing them to produce F1 dairy cows. However, for breeding decision based on total dairy merit, further investigations are needed for traits such as milk quality, reproduction, longevity and survival. Zusammenfassung Additive Rasseneffekte, nicht additive Effekte, Heritabilitäten und Wiederholbarkeiten für Milchmenge pro Laktation (LMY), Milchmenge pro Tag (DMY), Laktationsdauer (LL), jährliche Milchmenge (AMY), jährliche Milchmenge pro metabolischem Körpergewicht (AMYBW) und Kuhgewichte zur Kalbung (BW) wurden anhand von 5464 Laktationsdatensätzen von reinrassigen Boran (B), Friesian (F) und Kreuzungen der Rassen Friesian und Jersey (J) mit der Rasse Boran, die im tropischen Hochland von Äthiopien groß gezogen wurden, geschätzt. Einmerkmalsmodelle wurden mit zwei äquivalenten Wiederholbarkeits-Tiermodellen durchgeführt. Im ersten Modell wurde der Genotyp als fixer Gruppeneffekt berücksichtigt, während im zweiten Modell der Genotyp durch additive Rasseneffekte, Heterosis und Rekombinationseffekte als Kovariable ersetzt wurde. Die additiven Rasseneffekte von F und J, gemessen als Abweichung von der Rasse B, waren für alle Merkmale signifikant (p < 0,01), ausgenommen BW für die Rasse J. Die additiven Rasseneffekte von F und J betrugen 2774 ± 81 und 1473 ± 362 kg für LMY, 7,1 ± 0,2 und 4,8 ± 0,8 kg für DMY, 152 ± 7 und 146 ± 31 Tage für LL, 2345 ± 71 und 1238 ± 319 kg für AMY, 20,6 ± 0,9 und 18,9 ± 4,3 kg für AMYBW und 140 ± 4 und ,21 ± 22 kg (p > 0,05) für BW. Die Heterosis bei den Kreuzungstieren war positiv und signifikant für alle Merkmale (p < 0,01). Die Heterosis der F1 -Tiere, ausgedrückt als Abweichung vom Mittel der beiden Eltern, betrug 22 und 66% für LMY, 11 und 20% für DMY, 29 und 29% für LL, 21 und 64% für AMY, 42% und 42% für AMYBW und 2% (p < 0,05) und 11% für BW für die F × B und J × B Kreuzungen. Der geschätzte Rekombinationseffekt für die F × B Kreuzungen war negativ und signifikant für LMY (,526 ± 192 kg, p < 0,01), DMY (,3,0 ± 0,4 kg, p < 0,001), AMY (,349 ± 174, p < 0,05) und BW (,68 ± 11 kg, p < 0,001). Für die J × B Kreuzungen war der Rekombinationsverlust signifikant und negativ nur für DMY (,2,2 ± 0,7 kg, p < 0,05) und BW (,33 ± 17, p < 0,05). Die geschätzten Heritabilitäten (h2) betrugen für LMY, DMY, LL, AMY und AMYBW 0,24 ± 0,04, 0,19 ± 0,03, 0,13 ± 0,03, 0,23 ± 0,04 und 0,17 ± 0,05. Basierend auf den geschätzten genetischen Parametern erscheint Selektion in den Reinzuchtpopulationen B und F und anschließ end Kreuzung dieser Tiere zur Erstellung von F1 -Milchkühen als günstigste Zuchtstrategie, um die Milchproduktion unter äthiopischen Hochlandbedingungen zu steigern. Für Zuchtentscheidungen, die die gesamte Milchproduktion berücksichtigen, sind weitere Untersuchungen notwendig für Merkmale wie Milchqualität, Reproduktion, Persistenz und Langlebigkeit. 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