The effect of roasting nonlinted whole cottonseed on milk production by dairy cows

This study was conducted to examine the effect of roasting nonlinted whole cottonseed on ruminal crude protein (CP) degradability and performance in high-yielding dairy cows. Multiparous Israeli Holstein-Friesian cows (parity average 2.5 +/- 1.5; n = 132) with 571 +/- 65 kg of body weight (BW), 107 +/- 48 d in milk (DIM), and 37 +/- 5.8 kg of milk yield/d were used in the study. Cows were divided into two dietary treatment groups according to their BW, DIM, and milk production. The two diets were similar in CP, net energy for lactation, and neutral detergent fiber content [17%, 1.74 Mcal/kg, and 30% on a dry matter (DM) basis] and included either 15% (on a DM basis) whole cottonseed or roasted whole cottonseed. Ruminal effective degradability of CP, organic matter (OM), and ether extract (EE) decreased 14, 11, and 10%, respectively, compared to whole cottonseed. Total tract digestibilities of CP and EE were similar for both treatments and averaged 57 and 59%, respectively. However, DM and OM digestibilities were 6 and 5% higher in cows offered roasted whole cottonseed relative to those fed whole cottonseed diet. The inclusion of roasted whole cottonseed in the ration decreased ruminal ammonia and blood urea N concentration by 12% compared with diet with the raw whole cottonseed. Milk production, milk fat content, and production, and milk protein yield increased when roasted, nonlinted whole cottonseed was included in the diet. Milk protein content was similar for both treatments, averaging 2.92%.