Date of Graduation

7-2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Animal Science (PhD)

Degree Level

Graduate

Department

Animal Science

Advisor/Mentor

Elizabeth B. Kegley

Committee Member

Jason K. Apple

Second Committee Member

Jeremy G. Powell

Third Committee Member

Walter G. Bottje

Keywords

Beef cattle, Beef quality, Mineral status, Performance, Physiological response, Sodium sulfate

Abstract

For studies 1 through 3, 20 steers of predominantly Angus breeding, were stratified by body weight (279 ± 13.2 kg), assigned randomly to 6 paddocks, and fed a low S ground corn and soybean meal supplement that did not contain any byproduct feeds (0.31% total dietary S; LS) or LS supplement with an additional 0.25% S provided from sodium sulfate (Na2SO4; 0.58% total dietary S; HS) for a 114-d growing phase. Steers were moved to feedlot (373 ± 0.2 kg), remained on prior dietary S treatments, and fed corn and soybean meal diets (0.19 and 0.42% total dietary S; LS and HS treatments, respectively) that did not contain any byproduct feeds with no use of growth-enhancing technologies for a 123-d finishing phase. Steer performance was not affected (P ≥ 0.68) by dietary treatments during the growing phase. Steers fed HS experienced decreased dry matter intake (P < 0.001) and average daily gain (P = 0.07) during the finishing phase; however, on a carcass-adjusted basis, dietary treatments did not affect average daily gain (P = 0.24). Steers fed HS produced longissimus muscle (LM) with greater (P ≤ 0.08) total conjugated linoleic acid and 18:2cis9trans11 content than LM from steers fed LS; however, total conjugated linoleic acid content decreased (P = 0.09) during 7-d of simulated retail display. Finishing phase plasma Cu concentrations were less (P = 0.07) in steers fed HS than steers fed LS; however, plasma Cu concentrations were within the normal range and did not approach concentrations indicative of deficiency. Sulfhemoglobin production was greater (P < 0.001) in steers fed HS than steers fed LS (0.45 and 0.37%, respectively). Cytochrome c oxidase activity in liver and LM was not affected (P ≥ 0.38) by dietary treatment. For study 4, 36 primiparous beef heifers (20 ± 0.5 mo of age) of predominantly Angus breeding were stratified by body weight (398 ± 24.9 kg), body condition score, and anticipated calving date and assigned to 12 paddocks for a 260-d study. Pens were assigned randomly to 1 of 4 treatments (2 × 2 factorial): 1) 0.15% S and 6 mg Cu/kg; 2) 0.15% S and 12 to 14 mg Cu/kg (from tribasic copper chloride); 3) 0.55% S (from Na2SO4) and 6 mg Cu/kg; or 4) 0.55% S (from Na2SO4) and 12 to 14 mg Cu/kg (from tribasic copper chloride). A cracked corn and soybean meal based supplement delivered each treatment -113 to 150 ± 16 d relative to parturition. Heifer growth performance was not affected (P ≥ 0.19) by dietary treatments. Progeny from heifers fed 0.15% S and 6 mg Cu/kg exhibited lower birth weights (Cu × S interaction, P = 0.09); however, treatments did not affect (P ≥ 0.13) other measures of progeny growth performance. Heifers fed 0.55% S exhibited lower plasma and liver Cu concentrations and plasma ceruloplasmin activity (S main effect, P ≤ 0.07). Progeny liver Cu concentrations were similar among treatments and indicative of adequate liver Cu status in cattle, which was in contrast to maternal Cu indices.

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