Effects of zeranol and two dietary levels of calcium and phosphorus on performance, carcass and bone characteristics, and calcium status in growing lambs.
Seventy-two crossbred wether lambs (average initial weight, 25.1 kg) were used to determine the interaction between zeranol treatment and two dietary levels of Ca and P (.8 and .6% vs .4 and .3% Ca and P, respectively) in a 2 x 2 factorial arrangement on performance, carcass and bone characteristics, and serum concentrations of parathyroid hormone (PTH) and Ca. Lambs were implanted on d 0 and 56 with 12 mg of zeranol. Lambs had ad libitum access to feed for 105 d. On d 99, blood samples were collected. Implanted lambs had 12% greater (P less than .01) daily feed intake, 26% greater (P less than .10) ADG, and a 12% improvement in (P less than .10) feed efficiency compared with nonimplanted lambs. Zeranol-treated lambs had increased (P less than .05) bone cortical area, breaking load, and width of the metacarpal compared with nonimplanted lambs. Lambs fed the .8% Ca and .6% P diet had a higher (P less than .05) percentage of bone ash than lambs fed the .4% Ca and .3% P diet. However, there were no differences (P greater than .05) in the percentage of Ca, P, Mg, or Zn in metacarpal bones due either to higher dietary Ca and P or to implant treatments. Serum concentration of PTH was greater (P less than .10) in lambs fed .8% Ca and .6% P than in those receiving .4% Ca and .3% P. Serum concentrations of PTH and Ca pooled across treatments were greater (P less than .05) before feeding than at 1 h after feeding.(ABSTRACT TRUNCATED AT 250 WORDS)
Hutcheson
J P
JP
Department of Animal Science, Texas A&M University, College Station 77843.
Greene
L W
LW
Carstens
G E
GE
Byers
F M
FM
D000273:Adipose Tissue / Q000187:drug effects / Q000254:growth & development; D000818:Animals; D002118:Calcium / Q000097:blood; D002136:Calcium, Dietary / Q000008:administration & dosage*; D004343:Drug Implants; D004435:Eating / Q000187:drug effects; D008297:Male; D008460:Meat / Q000592:standards; D008663:Metacarpus / Q000033:anatomy & histology / Q000737:chemistry / Q000187:drug effects; D024510:Muscle Development; D009132:Muscles / Q000187:drug effects; D010281:Parathyroid Hormone / Q000097:blood; D016226:Phosphorus, Dietary / Q000008:administration & dosage*; D011897:Random Allocation; D012756:Sheep / Q000254:growth & development*; D015430:Weight Gain / Q000187:drug effects; D015029:Zeranol / Q000008:administration & dosage / Q000494:pharmacology*
D002136:Calcium, Dietary; D004343:Drug Implants; D010281:Parathyroid Hormone; D016226:Phosphorus, Dietary; D015029:Zeranol; D002118:Calcium