Abstract

Effects of underfeeding and supplementation on detailed milk components for 18 identical twin sets calving in July/August were assessed. Three treatments; 65% ad libitum pasture (R), 65% ad libitum pasture + 5.0 kg of cereal grain (S) and ad libitum pasture (F) were imposed in early (E), mid (M) and late (L) lactation. Milk was analysed for contents of fat, lactose and 12 nitrogen components. Treatment effects were generally greatest in E and M and often absent in L. Differences between F and R were significant by at least P>0.05, for 10, 7 and 2 of the 12 nitrogen components for E, M, L. Comparable differences for F-S were for E 6, M 5 and L 1. Changes were small in absolute terms and the extreme differences in type and level of feed suggest there is limited opportunity to manipulate nitrogen components in milk by feeding practices used in NZ.

SF, Petch, AM Bryant, and AR Napper

Proceedings of the New Zealand Society of Animal Production, Volume 57, , 154-156, 1997