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

Kegley, Elizabeth B.

Committee Member

Apple, Jason K.

Second Committee Member

Powell, Jeremy G.

Third Committee Member

Bottje, Walter G.

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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