Abstract
Two trials were conducted to determine the effects of Vitamin D₃ (VITD) on the tenderness of lamb: Trial 1 evaluated ionized Ca levels in blood serum, percent intake (PI), and total gain (TG) on 26 rams assigned randomly to one of eight treatments of VITD. These treatments were supplemented at one of four levels: 0 (S0); 250,000 IU of VITD (S250); 500,000 IU of VITD (S500); or 750,000 IU of VITD (S750) or administered as a bolus of 0 (B0); 250,000 IU of VITD (B250); 500,000 IU of VITD (B500); or 750,000 IU of VITD (B750) for four days. There were no (P > 0.05) differences at each day for treatment or treatment type for ionized Ca levels in blood serum. Rams assigned to the S500 treatment had lower (P < 0.05) PI and TG than other supplemented groups. Trial 2 evaluated carcass composition and Warner-Bratzler shear (WBS) values of chops from the longissimus lumborum (LL), semitendinosus (ST), semimembranosus (SM), and biceps femoris (BF) from each of 40 carcasses. Forty feedlot lambs were assigned randomly to one of two treatments of a control (CONT) (n=20) or 750,000 IU of VITD (n=20) and fed in a mock feedlot environment for four days before slaughter. There were no differences (P > 0.05) for ionized blood Ca levels in blood serum. Vitamin D₃ content in livers and kidneys differed (P < 0.01) between VITD vs. CONT (livers - 504.54 vs. 27.13 and kidneys - 1530.20 vs. 21.18 ng/g vitamin D[]). Carcasses from VITD treated lambs had less (P < 0.05) average fat thickness (0.68 vs. 0.84 cm) and an increase (P < 0.05) in overall conformation score. The four muscles were removed, fabricated into chops, and assigned randomly to a postmortem aging day of 5, 10, or 15 for WBS determination. Chops from the LL did not differ (P > 0.05) for WBS values for CONT vs. VITD for all aging days; however, chops from the SM and ST had (P < 0.05) lower WBS values for VITD vs. CONT at 5d aging. Activation and acceleration of calpain dependent proteases could be responsible for lower WBS values for chops aged 5 d; however, VITD regulators are most likely preventing VITD from increasing Ca levels in blood.
Boleman, Christopher Thomas (2000). Mechanisms of Vitamin D3 on tenderness of lamb. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2000 -THESIS -B63.