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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Publications at this Location » Publication #315489
Title: Mineral retention of serially slaughtered Holstein steers supplemented with zilpaterol hydrochloride

Author
item WATSON, ANDREA - University Of Nebraska
item MCEVERS, TRENT - West Texas A & M University
item WALTER, LEE-ANN - West Texas A & M University
item MAY, NATHAN - West Texas A & M University
item REED, J - University Of Nebraska
item Cole, Noel
item HUTCHESON, JOHN - Merck Animal Health
item LAWRENCE, TY - West Texas A & M University
item MACDONALD, JAMES - University Of Nebraska
item ERICKSON, GALEN - University Of Nebraska

Submitted to: Midwestern Section of the American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 12/15/2014
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Holstein steers (n = 115; 449 ± 20 kg) were utilized in a serial harvest trial measuring Ca, P, Mg, K, and S retention. A baseline group of 5 steers was harvested after 226 days on feed, which was designated d 0. Remaining cattle were assigned to 11 harvest groups, with slaughter every 28 d. Prior to slaughter, cattle were either not (CON) or were fed zilpaterol hydrochloride for 20 d followed by a 3 d withdrawal, immediately before scheduled slaughter (ZH). There were 5 steers per treatment in each slaughter group ranging from d 28 to 308. Whole carcasses were divided into lean, bone, internal cavity, hide, and fat trim components. Mineral retention within the body was calculated as the difference between mineral composition at slaughter and mineral composition at d 0. Mineral composition at d 0 was predicted from body composition of steers harvested at d 0 multiplied by the individual’s live weight at d 0. There were no differences in concentration of Ca, P, and Mg in bone tissue over time (P = 0.89); concentration of K, Mg, and S in lean tissue did fluctuate over time (P < 0.01). Averaged across treatment and days on feed, 99% of Ca, 92% of P, 78% of Mg, and 23% of S present in the body were in bone tissue; 67% of K and 49% of S were in lean tissue. Expressed as g/d, retention of all minerals decreased linearly across days on feed (P < 0.01). Expressed relative to EBW gain, Ca, P, and K retention decreased linearly over time (P < 0.01) and Mg and S retention increased linearly (P < 0.01) across days on feed. Retention of Ca was greater for CON cattle (greater bone fraction) and retention of K was greater for ZH cattle (greater muscle fraction) when expressed relative to EBW gain (P = 0.02), demonstrating the increase in lean gain by ZH cattle. There were no differences in Ca, P, Mg, K, or S retention due to treatment (P = 0.14) or time (P = 0.11) when expressed relative to protein gain. Retention averaged 14.4 g Ca, 7.5 g P, 0.45 g Mg, 1.3 g K, and 1.0 g S/100 g protein gain. Expressing mineral retention on a protein gain basis minimized effects of rate and type of gain. Feeding zilpaterol hydrochloride did not affect mineral retention when expressed relative to protein gain.