High Stocking Rate (high + stocking_rate)

Distribution by Scientific Domains

Selected Abstracts

How does grazing intensity influence the diversity of plants and insects in a species-rich upland grassland on basalt soils?

B. Dumont
Abstract The effect of stocking rate on the species richness, abundance and functional diversity of vascular plants, butterflies and grasshoppers was examined in a semi-natural upland pasture in central France. Over a 5-year period, 3ˇ6-ha plots were continuously grazed by Charolais heifers at 1ˇ4 (High stocking rate), 1ˇ0 (Intermediate) and 0ˇ6 (Low) livestock units (LU) ha,1. To evaluate botanical diversity, percentage cover of all plant species was estimated in late July in ten fixed 1 m × 1 m quadrats per plot. Butterflies were counted on three occasions between late June and early August along three fixed 50-m-long transects per plot using the ,Pollard walk', with grasshoppers being recorded on two occasions along the same transects. Diversity patterns of the three taxa were affected by stocking rate. For plants, species abundance changed more than species number. Abundance of forbs became higher under the Low compared with the High stocking rate. Stress-tolerant grasses were also more abundant in plots grazed at the Low stocking rate, while an opposite trend was observed for competitive grasses. Butterflies consistently responded to alterations in vegetation composition, especially to the dynamics of nectar plants. The species richness of grasshoppers also increased in plots at the Low stocking rate. The Low and Intermediate stocking rates were suitable for providing a high diversity of the three taxonomic groups. The results suggested that at least butterfly diversity would peak in vegetation taller than that of vascular plants. [source]

The influence of strain of Holstein-Friesian dairy cow and pasture-based feeding system on grazing behaviour, intake and milk production

S. 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]

Selective defoliation by sheep according to slope and plant species in the hill country of New Zealand

I. F. López
Abstract The objective of the study was to evaluate the grazing behaviour by sheep in hill country paddocks in New Zealand which had received two long-term fertilization and stocking rate treatments [high fertility,high stocking rate (HH); low fertility,low stocking rate (LL)]. Herbage accumulation and selective grazing were evaluated within low slope (LS), medium slope (MS) and high slope (HS) categories. Transects lines were placed and tillers of Agrostis capillaris and Lolium perenne in the LS category; A. capillaris, Anthoxanthum odoratum and L. perenne in the MS category; and A. capillaris and A. odoratum in the HS category were marked. The leaf length of each marked tiller was measured and used to determine selective grazing over 3 weeks during each season. The highest herbage accumulation rates were during spring and the lowest in summer and winter. The LS category showed the highest herbage accumulation rates and HS the lowest. Except for autumn, the marked tillers were more frequently grazed in the HH than in the LL paddock. During summer, autumn and spring, grazing frequency in the slope categories was in the order LS > MS > HS. During winter sheep did not discriminate between slope category. During summer, autumn and spring, sheep did not selectively graze the species studied but this was not the case during winter. Overall, sheep selectively grazed L. perenne. In all the seasons L. perenne consistently had the longest leaves but within species there was no consistent relationship between leaf length and probability of being grazed. Selective grazing changed through the year according to herbage accumulation rate. Sheep concentrated grazing in the category LS when herbage accumulation rate was high, but they did not discriminate between slope categories in winter when herbage accumulation rate was low. [source]

Changes in heathland vegetation under goat grazing: effects of breed and stocking rate

Rafael Celaya
Abstract Questions: How are heathland vegetation dynamics affected by different goat grazing management? Location: Cantabrian heathlands in Illano, Asturias, northern Spain. Methods: During 4 years, vegetation dynamics (structural composition, canopy height and floristic diversity) were studied under three goat grazing treatments with three replicates: high stocking rate (11.7 goats ha,1) with a local Celtiberic breed, and high (15 goats ha,1) and low (6.7 goats ha,1) stocking rates with a commercial Cashmere breed. Results: The relative cover of woody plants, particularly heather species, decreased more while herbaceous cover increased more under local Celtiberic than under Cashmere breed grazing. Within Cashmere treatments, the cover and height of live shrubs decreased more and the herbaceous cover increased more under high than under low stocking rate. Redundancy analysis showed a significant effect of treatment × year interaction on floristic composition. Greater species richness was recorded under local goat grazing, but Shannon diversity index fell in the fourth year on these plots because of dominance by two grass species. Conclusions: Local Celtiberic goat grazing at such a high stocking rate (11.7 goats ha,1) hinders the development of sustainable systems on these heathlands, both in environmental and productive terms, owing to the limitations in soil fertility. Nevertheless, Celtiberic goats could be useful for controlling excessive shrub encroachment and reducing fire hazard. Cashmere goat grazing at high stocking rate promoted the highest Shannon diversity by generating a better balance between woody and herbaceous plants, while shrub dominance was not altered under the low stocking rate. [source]