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Mean Litter Size (mean + litter_size)
Selected AbstractsAspects of the feeding habits and reproductive biology of the Ghana mole-rat Cryptomys zechi (Rodentia, Bathyergidae)AFRICAN JOURNAL OF ECOLOGY, Issue 2 2002S. Yeboah Abstract The feeding habits and reproductive biology of the Ghana mole-rat, Cryptomys zechi (Matchie), were studied in a Guinea savanna woodland in Ghana. Both tunnel contents and stomach content analysis indicated that bulbs and tubers constituted the commonest and most preferred food items, although some animal food materials were also consumed. Five plant species, Urgenia altissima, Manihot utilisima, Curuligo sp., Oxalis corniculata and Archis hypogea, were the most popular plant food source. Breeding occurred during the rainy season (March,August) and was at its peak in July. There is evidence that the species is capable of producing two litters in a year. In a colony, reproduction is restricted to one female and one male. Males reached sexual maturity at a lower body weights (105 g) than females (155 g). Estimated mean litter size was 1.5 (range 1,2), the smallest among the bathergids. Available data on birth weights of three other species of social Cryptomys indicate that C. zechi has the highest birth weight, which is comparable to that of solitary bathyergids. Résumé On a étudié les habitudes alimentaires et la biologie de la reproduction du rat-taupe du Ghana, Cryptomys zechi (Matschie), dans une savane guinéenne arborée au Ghana. L'analyse du contenu des terriers et des estomacs indique que les bulbes et les tubercules constituent les aliments les plus fréquents et les plus appréciés, bien qu'ils mangent aussi un peu de matière animale. Cinq espèces végétales, Urgenia altissima, Manihot utilissima, Curuligo sp., Oxalis corniculata et Archis hypogeaétaient les sources de nourriture végétale les plus appréciées. L'accouplement a lieu pendant la saison des pluies (mars , août) et est à son maximum en juillet. Des preuves montrent que l'espèce peut produire deux nichées par an. Dans une colonie, la reproduction est limitée à un mâle et une femelle. Les mâles atteignent la maturité sexuelle à un poids inférieur (105 gr) à celui des femelles (155 gr). On a estimé que la taille moyenne d'une nichée était de 1,5 jeune (allant de 1 à 2), la plus petite chez les rats-taupes. Les données disponibles sur le poids à la naissance de trois autres espèces de Cryptomys sociaux indiquent que C. zechi a le poids le plus important à la naissance, comparable à celui des rats-taupes solitaires. [source] ORIGINAL ARTICLE: In Vitro and In Vivo Studies Evaluating Recombinant Plasmid pCXN2-mIzumo as a Potential Immunocontraceptive AntigenAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 3 2009Gang An Problems, Study on feasibility of pCXN2-mIzumo as a potential immunocontraceptive antigen. Method of study, Two groups of mice received 100 ,g/mouse plasmids of pCXN2-mIzumo and pCXN2 respectively. RT-PCR Immunofluorescence assay and ELISA were performed to observe pCXN2-mIzumo expression and antibody response in the inoculated mice. Sperm penetration assay and animal mating were employed to detect differences of in vitro fertilization (IVF) rate and mean litter size between the experimental and control groups. Results, Izumo cDNA positive bands were detected in sample from mice immunized with pCXN2-mIzumo. IgG response started to rise at 2 weeks after first boost and reached the highest antibody titers at 2 weeks after third boost of immunization with pCXN2-mIzumo in the experimental mice. In vitro fertilization rate in the experimental group (11.57%) was significantly lower than that in control (36.60%). Significant difference of mean litter size between female experimental and control groups was observed, and there was significant negative correlation between individual anti-serum titers and litter size (r = ,0.308, P < 0.05). Conclusion, pCXN2-mIzumo plasmid possesses appreciable anti-fertility potential. [source] Litter size and latitude in a large mammal: the wild boar Sus scrofaMAMMAL REVIEW, Issue 3 2010Kirsten A. BYWATER ABSTRACT 1A positive relationship between clutch size or litter size and latitude exists in birds and many species of small mammal. Hitherto, however, analyses for large mammals have failed to provide evidence that litter sizes increase with latitude. 2We collated data from published studies of wild boar in Europe, to analyse the relationship between litter size and latitude in this widely distributed terrestrial mammal. 3Depending on the specific data set (whether only the most reliable data or all available data were included), latitude explained 58% to 72% of the variation in mean litter sizes across studies. On average, litter size increases by approximately 0.15 piglets per degree of latitude. 4A strong correlation between litter size and latitude for wild boar in Europe provides a starting point for demographic modelling of this species of both ecological and economic importance. 5The pattern for wild boar is consistent with Ashmole's explanation for the effects of latitude on reproduction. The contrast between our results and those generated for other large mammals may result from our focus on an herbivore in contrast to previous work which was focused on carnivores. Further work could usefully examine the extent of seasonality in the availability of resources for species of different dietary types. [source] Prolonged Duration of Fertility of Dog OvaREPRODUCTION IN DOMESTIC ANIMALS, Issue 2009T Tsutsui Contents The fertile period for natural mating in dogs extends from before ovulation until day 5 post ovulation (PO) and involves a delay in oocyte maturation until 2,3 days PO and viability of secondary oocytes for 48,60 h or more. Spermatozoa do not enter the uterus after vaginal insemination in late oestrus. Cervical closure appears to occur on average 5 days PO, but conception may occur following intrauterine artificial insemination (IUAI) up to 8 days PO. Therefore, the present study was conducted to clarify the duration of fertility of canine ova. Using IUAI at 6, 7, 8 and 9 days PO (n = 5 bitches each) conception rates were 100%, 71.4%, 37.5% and 0%, respectively, with an average litter resorption rate of 30.8%, and with mean litter sizes and times to delivery PO being 4.3 ± 1.6 and 64.3 ± 0.3 days, 4.0 ± 1.4 and 66.3 ± 0.4 days, and 2.5 and 68 days for IUAI at 6, 7 and 8 days, respectively. The high pregnancy rates with IUAI at 6 and 7 days PO confirm that many canine oocytes are fertile at 4,5 days after maturation. The high rate of resorption was presumably because of aging of ova or asynchrony between embryonic development and the intrauterine environment. [source] | |||||||||||||