Milk Production and Plasma Gossypol of Cows Fed Cottonseed and Oilseed Meals with or Without Rumen-Undegradable Protein

Abstract

Twenty-four multiparous Holstein cows were randomly assigned at calving to treatment diets using a modified split-plot design to determine the effects of protein source on milk production and composition. The treatment diets consisted of an 80:20 combination of corn and alfalfa silages and whole cottonseed at 12% of the dietary dry matter (DM). The treatment diets were formulated to contain 17% crude protein (CP) and 20% acid detergent fiber on a DM basis. One of the following sources of supplemental CP was included in each treatment diet: 1 ) cottonseed meal, 2 ) cottonseed meal plus a rumenundegradable protein (RUP) supplement, 3 ) soybean meal, and 4 ) soybean meal plus an RUP supplement. Cows were fed the initial treatment diet for 6 wk and then were switched to the other oilseed meal source but continued to receive the same amount of RUP during the second period of the study.