Replacing soybean meal for cottonseed meal on performance of lactating dairy cows.

Cottonseed meal (CSM) is an alternative source of protein, and previous studies have been shown that it can replace soybean meal (SBM) without decrease animal performance. However, Brazilian CSM has a different chemical composition compared with the usual CSM reported in the literature. The objective of this experiment was to evaluate the effects of replacing SBM for Brazilian CSM on performance and energy balance of mid-lactating dairy cows. Forty-two Holstein cows were used in a replicate 3 × 3 Latin square design. Increasing contents of CSM (0, 15, and 30% of dry matter (DM)) were fed in diets to replace SBM. Milk yield and feed efficiency were linearly reduced with the replacement of CSM for SBM (P = 0.001). Milk fat content tended to increase quadratically (P = 0.07) with CSM addition. Replacing SBM for CSM affected milk protein content quadratically (P = 0.05). Milk urea nitrogen and plasma urea nitrogen (PUN) tended to respond quadratically (P = 0.06 and 0.10) when CSM replaced SBM to the diets. Variation in body weight (BW) also responded quadratically as CSM replaced SBM (P = 0.05). Altogether, the findings suggest better performance when cows receive SBM diet compared with the Brazilian CSM diet.