Protection of Unsaturated Fatty Acids of Hay Against Biohydrogenation in Rumen and its Impact of Milk Yield and Composition
Abstract
Good quality ryegrass-clover hay was treated with HCHO (2g/100g DM of hay). It was observed that a maximum of 52 AND 58% of 18:3 and 18:2 remained unhydrogenated, respectively, after 24 h incubation of treated hay. The corresponding values with untreated hay were 14 and 21%. Changesin 18:1 and 18:0 complemented changes in 18:3 and 18:2. The pattern of in vivo biohydrogenation of 18:3 and 18:2 on tteated and funtteated hay was she same as observed in in vitro but the extent of biohydrogenatton in former was also considerable when treated hay was fed. Milk yield and the contents of fat and protein were not significantly different when a pair of monozygous twin cos were fed untreated or treated hay. The proportions of 18 : 3 and 18:2 in the total milk fat were elevated from 0.64 to 0.96 and from 134 to 1.63%, respectively when treated hay was fed. However, this Increase in unsaturated fatty acids in milk fat was considerably less than the expected values possibly due to lesser protection of these fatty acids against ruminal biohydrogenation because of levels of HCHO used in this study.
