Sulfur metabolism in beef cattle and management strategies to improve performance and health in newly weaned beef cattle

Five experiments were conducted at Colorado State University's Research Centers. Three experiments were conducted to evaluate sulfur metabolism in beef cattle. The final 2 experiments were conducted to evaluate receiving strategies to improve feedlot performance and cattle health in newly weaned beef cattle.;In experiment 1, rumen fluid from fistulated steers receiving a high roughage (ROU) ; 50% alfalfa hay, 50% corn silage) or a high concentrate-based diet (CON) ; 70% rolled corn, and 30% corn silage) was utilized to examine in vitro hydrogen sulfide (H2S) production of common beef cattle feedstuffs (FS). Across diets (ROU vs. CON), fermentation of corn produced the lowest pH and fermentation of alfalfa produced the highest pH; however, across FS, ROU had a higher pH when compared to the CON rumen fluid. These data suggest that type of rumen fluid (ROU vs. CON) and FS can influence the production of H2S. Understanding factors that influence H 2S production within the rumen may be useful when formulating beef cattle diets.;In experiment 2, two rumen fistulated cross bred steers were fed ROU for a minimum of 21 d prior to experiment initiation. No 3- or 4-way interactions were found when S loss per unit DMD was analyzed. The main effect of FS resulted in DDG having the greatest (P < 0.0001) S released per unit DMD and corn released the least, in CON and ROU diets (2.63 and 4.22 vs. 1.15 and 1.03 mg/g +/- 0.566) averaged over all time periods. These data suggest that there may be differences in the release of S from different FS in different diets. This finding may be due to the ratio of S types in a FS (i.e. organic to inorganic) or nature of the microbial population associated with the fermentation of CON vs. ROU diets.;In experiment 3, Crossbred yearling steers (n = 432) were used to study the effects of Laidlomycin and Chlortetracycline (LC) vs. Monensin and Tylosin (MT) and variation in S intake on rumen fluid pH and rumen gas hydrogen sulfide (H2S) concentration. An unbalanced randomized block design using a 2 x 2 factorial arrangement of treatments was utilized. Factors included feed additive (LC vs. MT) and S concentration (constant vs. variable). The effects of feed additive, dietary S, or the interaction on rumen fluid pH were not significant (P > 0.38). An interaction between feed additive and dietary S treatment ( P < 0.02) existed suggesting that the effect of feed additive on H2S concentration was influenced by dietary S.;In experiment 4, 442 newly weaned Angus and Angus crossbred steers (initial BW = 234 +/- 40.4 kg) were selected from an initial group of 453 from 3 ranches in CO. These steers were used to evaluate the effect of implant timing on feedlot performance and health. Live BW was recorded on d 0, 28, 56, 112, 169 and prior to harvest. On d 0, 5 steers from each pen were vaccinated with 2 mL of ovalbumin (OVA) subcutaneously and 1 mL was administered intradermally. On d 28 the same 5 steers received a booster of the OVA and 5 novel steers also receive a vaccination of OVA. This allowed a d 0 and d 28 primary responses to be evaluated along with a d 28 secondary immune response.;In experiment 5, 124 newly weaned Angus, Hereford, and Angus x Hereford bull and heifer calves (initial BW = 233 +/- 14.9 kg) were utilized to evaluate 2 feedlot receiving management strategies at Colorado State University's Agricultural Research, Development, and Education Center in Fort Collins, CO on feedlot performance over the first 30 d upon arrival to the feedlot. Providing a DDG-based receiving ration to newly weaned calves upon arrival to the feedlot resulted in greater feed intake, gain, and feed efficiency over a 30 d period than traditional long-stemmed grass hay followed by a non-DDG total mixed ration. (Abstract shortened by UMI.).