The ability of sheep at different stocking rates to maintain the quality and quantity of their diet during the grazing season

Journal of Agricultural Science - Tập 140 Số 1 - Trang 113-124 - 2003
Florence Garcia-Launay1, Pascal Carrère2, Jean‐François Soussana2, René Baumont3
1INRA-Unité de Recherches sur les Herbivores, Relations Animal Plantes, Site de Theix, 63122 St-Genès-Champanelle, FranceINRA-Agronomie, Fonctionnement et Gestion de l'Ecosystème Prairial, 234 Av. du Brézet, 63039 Clermont-Ferrand, France
2INRA-Agronomie Fonctionnement et Gestion de l'Ecosystème Prairial 234 Av. du Brézet 63039 Clermont-Ferrand France
3INRA-Unité de Recherches sur les Herbivores, Relations Animal Plantes, Site de Theix, 63122 St-Genès-Champanelle, France

Tóm tắt

The degree to which grazers maintain the amount (organic matter intake) or the quality (organic matter digestibility) of their diet without adversely affecting the other component was addressed by investigating how sheep managed trade-offs between quantity and quality throughout the grazing season in an upland area of central France. Two groups of five dry ewes, grazing two plots of contrasting areas from April to the end of September 2000, were studied. On the smaller plot (1500 m2), the application of a high stocking rate (HSR) produced a resource of good quality but in low quantity; and on the larger plot (3000 m2), a low stocking rate (LSR) created a sward of low quality but in good quantity. In spring, in both conditions, the sheep maintained their intake of digestible organic matter (OM) at between 1000 and 1250 g/day. Both organic matter intake and digestibility remained high at both stocking rates. In summer, the intake of digestible OM decreased to between 750 and 1000 g/day. On HSR, this was mainly due to a decline of intake in relation to the decrease of intake rate and bite weight. On LSR a decrease in digestibility and to a lesser extent in intake was involved. At both stocking rates, the sheep maximized the digestibility of their diet by selecting the green laminae throughout the grazing season. In spring, the sheep modulated their daily grazing time to compensate the decrease in intake rate and maintained a high daily intake. In summer and autumn, the sheep failed to maintain their daily intake at the same level as previously observed. On both plots they modulated their daily grazing time to cover their needs (730 g/day), but they did not increase it further to maximize daily intake. This may be attributable to the costs involved in selecting (LSR) or taking (HSR) the best components from the sward.

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Journal of Agricultural Science

Tập 140 Số 1

113-124

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