The feeding value of whole cottonseed in the diets of lactating dairy cattle
Cooke, Kelly Michelle
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Coating whole cottonseed with starch alters rumen fermentation and decreases fiber digestibility. The objective of this research is to investigate the effects of the addition of value added feeds to the starch coating on in vitro ruminal fermentation and performance of lactating dairy cows. In vitro fermentation results indicate that as starch increased, pH decreased while concentrations of ammonia increased. The addition of yeast culture decreased total VFA and acetate: propionate ratio due to an increase in molar proportions of propionate. Dry matter and fiber digestibility were improved with the addition of urea and sodium bicarbonate to the coating. Results of production performance indicate that addition of urea and yeast to the starch coating did not affect dry matter intake, nutrient digestibility, or milk yield. Efficiency of milk production was higher for the urea and yeast treatments compared with control. Results of these trials indicate that including urea, yeast culture, and sodium bicarbonate alters fermentation and dry matter and fiber digestibility in vitro. Production trial results indicate that inclusion of urea or yeast culture in the gelatinized starch coating does not change whole tract digestibility, but does improve milk production efficiency. Delayed harvest of the cotton plant increases free fatty acid content in the seed which has been shown to alter rumen fermentation but not nutrient digestibility. The objective of this research is to examine the effects of feeding whole cottonseed with elevated concentrations of free fatty acids in the oil on intake and performance. Treatments included whole cottonseed with three concentrations of free fatty acids; 6.8 %, 24.1 %, and 22.3 % free fatty acids. Yield of milk and components was similar among treatments, but milk fat percentage was lower for elevated free fatty acid treatments compared with control. Molar proportions of butyrate and isobutyrate increased with elevated free fatty acids. Results indicate that changes in ruminal fermentation were not sufficient enough to decrease milk fat percentage and reduction probably occurs due to effects of reduced total fatty acid supply to the mammary gland for de novo synthesis of milk fat.