Effects of Calcium Salts of Long-Chain Fatty Acids on Growth, Reproductive Performance, and Hormonal and Metabolite Concentrations in Pubertal Beef Heifers and Postpartum Cows

Abstract

Pubertal Angus heifers and postpartum Angus cows were used to study the effects of supplemental calcium salts of long-chain fatty acids (CLCFA) added to forage-based diets on growth, reproductive performance, and hormonal and metabolite concentrations. In Experiment 1, heifers were fed corn (control; n = 20) or corn plus Megalac® (CLCFA; n = 20). Supplements were isoenergetic and fed for 123 d prior to breeding. Blood samples, BW, and hip heights were obtained on d 0, 32, 60, 88, 123, and 260. Growth, serum leptin, early pregnancy progesterone concentrations, and reproductive performance, except for calving rate, were not different. Calving rate for heifers fed ClCFA tended to be greater (P=0.12) than that of heifers fed a control diet. Serum cholesterol increased (P<0.01) over time only in heifers fed ClCFA; however, ClCFA increased (P<0.01) concentrations of serum triglycerides only on d 32 and 123. Experiment 2 was conducted to determine the effects of ClCFA on reproductive performance of postpartum cows receiving chelated (CHEL; n = 36) or inorganic (INORG; n = 38) mineral supplements. Beginning 28 d prior to estrus synchronization, cows within each mineral group were fed the control diet or the diet containing corn plus CLCFA, as in Experiment 1, for 54 d. Blood samples and BW were obtained on d 0, 28, and 56. Weight loss was greater (P<0.01) in cows receiving INORG supplements than in cows receiving CHEL supplements; however, CLCFA reduced (P<0.01) the amount of BW lost in cows receiving INORG supplements but not in cows receiving CHEL supplements. Overall, concentrations of serum cholesterol and triglyceride and reproductive performance, excluding calving interval, were not significantly affected by CLCFA. Calving interval tended to be longer (P=0.06) in cows fed CLCFA.