Digesta flow and rumen microbial protein production in ewes grazing perennial ryegrass [sheep]
1994
Dove, H. (Commonwealth Scientific and Industrial Research Organisation, Canberra (Australia). Div. of Plant Industry) | Milne, J.A. (Macaulay Land Use Research Inst., Aberdeen (United Kingdom))
Herbage organic matter (OM) intakes and the abomasal flows of OM, non-ammonia nitrogen (NAN) and microbial nitrogen (MN) were estimated in ewes grazing perennial ryegrass during lactation in spring-summer (Group 1) or in autumn after the end of lactation (Group 2). On average, ewes in Group 1 consumed 804 g OM per day more than ewes in Group 2, while their daily abomasal flows of OM, NAN and MN were, respectively 372, 28.2 and 26.7 g per day more than those in Group 2 ewes. The regression equations relating to flows of digesta or digesta components to OM intake were significantly different between the 2 groups of ewes. Results are presented to suggest that the observed differences between the 2 groups were due to differences in the composition of the consumed herbage in autumn compared with spring-summer. The inclusion, in multiple regression analyses, of either rumen propionate or rumen acetate: propionate ratio, together with OM intake explained approximately 0.80-0.85 of the variance in NAN or MN flows, reduced residual standard deviations compared with fitting OM intake alone, and removed the difference between the 2 groups of ewes.
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