Evaluation of Bt cottonseed as a protein supplement in the ration of lactating dairy cows

Abstract

Crossbred (Karan Swiss and Karan Fries) multiparous cows (20), housed in a well ventilated shed, were fed berseem (green fodder) ad lib. wheat ~traw (1 kg/cow/day) and a concentrate mixture consisting of crushed cottoflseed 40 palis according to their nutritional requirements for 13 days to adapt them to the cottonseed based diet. Average daily milk yield in these groups was 7.75 kg during the adaptation period. Thereafter, cows were divided in 2 groups of 10 each ~n the basis of their stage of lactation and milk yield. Group 1 (non-Bt) was continued on the same ration while in the concentrate mixture of group 2 cottonseed was replaced with transgenic cottonseed and designated as Bt group. Milk yield and voluntary feed intake were recorded daily for 4 weeks. The amount ofBt protein in Bt cottonseed was 52 Ilg/g cottonseed. Voluntary DM intakell 00 kg body weight varied in the Bt group and non-Bt group, and cows maintained their body weight during the study. Average milk yield and milk composition including fat, protein, lactose, SCC and fatty acid composition of milk fat did not vary between groups. DM intake/IOO kg body weight, nutrient digestibility and plane of nutrition in both the groups did not vary significantly between the groups. Milk and blood plasma samples did not exhibit the presence ofBt protein in both the groups at any stage of sampling in lactating cows. Lactating dairy cows pel'formed in a similar fashion when fed Bt and non-Bt cottonseed during the experiment.