DEVELOPMENT OF AN EFFICIENCY RANKING SYSTEM FOR BEEF COWS AND A COMPARISON OF THE DIGESTIVE PHYSIOLOGY BETWEEN EFFICIENT AND INEFFICIENT COWS

Beef cows (n = 100) were used in a 2-yr selection system based on cow rump fat thickness at calving, calving date, and calf weaning weight (% dam BW). The 9 most (ME) and least efficient (LE) cows were used to compare feed intake and ruminal fermentation using four 26-d periods with decreasing dietary nutrient density. There were no phenotype × diet interactions for variables of primary interest. Rump fat and calf weaning weight were greater and calving date was earlier for ME than LE (P ≤ 0.032). The ME cows were lighter (P < 0.001) but had similar DMI (P = 0.93) to LE cows, resulting in greater DMI (%BW; P < 0.001). Ruminal contraction amplitude height and area (P ≤ 0.015), and ruminal digesta weight were greater for LE than ME cows (P = 0.043). Ruminal aNDFom passage was greater for ME cows than LE cows (P = 0.047) but the rate of aNDFom degradation did not differ (P = 0.69). Total tract digestibility did not differ. Efficient cows had greater rump fat, weaned heavier calves, ate more relative to their BW, had smaller ruminal digesta mass, and greater ruminal passage of aNDFom without reducing digestibility

DEVELOPMENT OF AN EFFICIENCY RANKING SYSTEM FOR BEEF COWS AND A COMPARISON OF THE DIGESTIVE PHYSIOLOGY BETWEEN EFFICIENT AND INEFFICIENT COWS

Beef cows (n = 100) were used in a 2-yr selection system based on cow rump fat thickness at calving, calving date, and calf weaning weight (% dam BW). The 9 most (ME) and least efficient (LE) cows were used to compare feed intake and ruminal fermentation using four 26-d periods with decreasing dietary nutrient density. There were no phenotype × diet interactions for variables of primary interest. Rump fat and calf weaning weight were greater and calving date was earlier for ME than LE (P ≤ 0.032). The ME cows were lighter (P < 0.001) but had similar DMI (P = 0.93) to LE cows, resulting in greater DMI (%BW; P < 0.001). Ruminal contraction amplitude height and area (P ≤ 0.015), and ruminal digesta weight were greater for LE than ME cows (P = 0.043). Ruminal aNDFom passage was greater for ME cows than LE cows (P = 0.047) but the rate of aNDFom degradation did not differ (P = 0.69). Total tract digestibility did not differ. Efficient cows had greater rump fat, weaned heavier calves, ate more relative to their BW, had smaller ruminal digesta mass, and greater ruminal passage of aNDFom without reducing digestibility

Influence of long-term supplementation of a formulated botanical blend on growth performance and carcass traits in feedlot steers

Objective The objective of this study was to determine if a formulated blend of capsicum oleoresin, clove essential oil, and garlic essential oil (Fytera Advance - Selko USA, Indianapolis IN, USA; CCG) influences measures of cattle growth, efficiency, or carcass traits, during the finishing phase in steers fed a concentrate-based diet. Methods Charolais×Angus steers (n = 96; initial shrunk body weight [BW] = 391±34.0 kg) were used in a 144-d (16 February 2023 to 9 July 2023) finishing feedlot experiment in Brookings, SD, USA. Steers were individually weighed and allotted to one of 14 pens (6 to 7 steers; 7 pens/treatment) in a randomized complete block design and randomly assigned to 1 of 2 treatments: control diet without the test product (CON) or a diet including CCG at 500 mg/steer daily (CCG). Steers were fed twice daily, and bunks were managed according to a slick bunk system. Results There were no differences (p≥0.10) in any growth performance outcomes from d 1 to 35, 36 to 70, or 71 to 98. From d 99 to 144 steers from CCG tended to have 5% greater average daily gain (p = 0.09) and 8% improved feed conversion (G:F) (p = 0.01). No differences (p≥0.15) were noted for cumulative growth performance measures. No differences were noted for any carcass measurements or categorical carcass outcomes, nor lung or liver health outcomes (p≥0.15). Conclusion The use of CCG had no influence on cumulative growth performance responses. However, the use of CCG improved G:F during the late feeding period