Author:
WACHIRA A. M.,SINCLAIR L. A.,WILKINSON R. G.,HALLETT K.,ENSER M.,WOOD J. D.
Abstract
The study examined the extent to which n-3 PUFA from different sources were biohydrogenated in
the rumen and their effects on rumen microbial efficiency and whole tract nutrient digestibility. Four
ruminally and duodenally cannulated wether lambs were used in a 4×4 Latin square design. Four
iso-energetic and iso-nitrogenous diets based on dried grass were formulated to provide similar fat
levels (60g/kg DM) from different sources; Megalac (palmitic acid: C16:0; Control), whole linseed
(α-linolenic acid, C18:3n-3 ; Linseed) fish oil (eicosapentaenoic acid, C20:5n-3, EPA and
docosahexaenoic acids C22:6n-3, DHA; Fish oil) and whole linseed plus fish oil providing equal
amounts of oil (LinFish). Diets were offered at a rate of 1·2kg/day in 12 equal portions.Total fatty acid intake was similar on all diets whilst duodenal fatty acid flow varied between
101, 94, 87 and 90% of dietary intake for animals fed the Control, Linseed, Fish oil and Linfish diets
respectively. Duodenal flow of C18:3 n-3 in animals fed the Linseed diet was twice that of animals
fed the Control diet (P < 0·01) whilst animals fed the Fish oil diet had a significantly greater flow of
EPA and DHA than those fed any of the other dietary treatments. Duodenal flow of trans C18:1 in
animals fed the Linfish diet was significantly greater than that in animals fed either Linseed, Fish oil
or Control diets (P < 0·001). Biohydrogenation of C18:3n-3 was 80 to 93% in all diets whilst that
of C20:5n-3 and C22:6n-3 was 72 to 79% in diets that contained fish oil or linseed and fish oil.
Apparent fatty acid digestibility (duodenum to rectum) tended to be greater for unsaturated than
saturated fatty acids whilst whole tract fatty acid digestibility (mouth to rectum) was significantly
greater in animals fed diets containing fish oil (P0·05). All dietary n-3 PUFA sources decreased
microbial protein synthesis and efficiency when expressed as either gN/kg organic matter (OM)
apparently or truly degraded in the rumen. Additionally, the inclusion of fish oil increased the
proportion of propionate in the rumen whilst depressing the rumen digestibility of OM and fibre
(P < 0·01), but had no significant effect on whole tract OM or fibre digestibility.
Publisher
Cambridge University Press (CUP)
Subject
Genetics,Agronomy and Crop Science,Animal Science and Zoology
Cited by
99 articles.
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