Methods to improve growth efficiency in beef cattle
[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT AUTHOR'S REQUEST.] Genetics, nutrition and animal management each have integral roles in maximizing growth efficiency of domestic livestock. Residual feed intake (RFI) is an accurate method of distinguishing between feed efficient and inefficient animals. Because RFI is independent of growth and BW it can be selected upon without influencing mature size of the animal. Yet some of the physiological mechanisms which contribute to variation in RFI are unaccounted for. However, debate remains on the amount of variation accounted for among known variables. Adequate supply of rumen undegradeable protein (RUP) within the diet for growing cattle is essential in meeting limiting amino acid (AA) requirements that cannot be fulfilled by microbial protein. Supplementing feedstuffs with greater RUP tend to be the most expensive ingredient within a diet. Alternative methods that increase RUP at a lesser expense are beneficial in reducing production costs while maintaining animal efficiency. Several sorting strategies exist within the feedlot to sort cattle into uniform feeding groups with the intent of avoiding carcass discounts for over or under fattened carcasses along with too heavy or too light of carcasses. Sorting cattle on actual growth potential may not only maintain uniformity in feeding groups but also improve growth efficiency. Grouping cattle by actual growth potential would allow for greater precision in diet formulation. The initial study consisted of two experiments which examined fermentation characteristics and nutrient digestion between beef cattle of contrasting feed efficiencies in mixed rumen cultures.
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