Effect of dietary glucosinolates on nutrient utilization, milk yield and blood constituents of lactating goats

Sixteen crossbred (Alpine × Beetal) lactating does were divided into two equal groups on the basis of milk yield, stage of lactation and lactation number. Group I was fed a concentrate containing groundnut cake as the sole protein source. In Group II groundnut cake was replaced with mustard cake containing 139.4 μmol/g glucosinolate, on a protein basis. Both concentrate mixtures were isocaloric and isonitrogenuous, however the Group II concentrate contained 57.5 μmol/g glucosinolate, resulting in an average 13.04 g glucosinolate intake per goat. Dietary glucosinolate affected the palatability of the diet and reduced (P < 0.01) the intake and CP digestibility in Group II. Digestibility of dry matter, organic matter, cell wall components, 4% fat corrected milk yield and milk production efficiency were similar in both groups. Dietary glucosinolate increased (P < 0.05) the milk thiocyanate and decreased (P < 0.01) the iodide content. Milk fat, protein, total solids, solid-not-fat and urea concentration were however not affected. Feeding of glucosinolates diets reduced (P < 0.05) the plasma T4 concentration, with plasma T3 concentration not being affected. Plasma iodide, total protein, urea and creatinine content as well as activity of γ-GTP were unaffected by dietary glucosinolate. Dietary glucosinolates adversely affected the palatability of the diet, increased milk thiocyanate and reduced milk iodide content and also reduced the plasma T4 concentration without affecting nutrient utilization, milk yield and other milk composition. Costlier groundnut cake can be totally replaced by high glucosinolate containing mustard cake in the diet of lactating goats.