Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2002
Publication Date: 6/2/2002
Citation: GEARY, T.W., GRINGS, E.E., MACNEIL, M.D., KEISLER, D.H. EFFECTS OF FEEDING HIGH LINOLEATE SAFFLOWER SEEDS PREPARTUM ON LEPTIN CONCENTRATION, WEANING, AND RE-BREEDING PERFORMANCE OF BEEF HEIFERS. WESTERN SECTION OF ANIMAL SCIENCE PROCEEDINGS. 2002. v. 53. p. 425-427. Interpretive Summary: This study was designed to identify the mechanism(s) by which supplemental fat in the prepartum diet might improve calf and rebreeding performance. Other than improved calf vigor, no differences were detected that would suggest any beneficial effect of providing first calf heifers a prepartum diet high in fat. However, given the typical variability among animals for many of the phenotypes observed, concluding that these diets had similar effects may be premature.
Technical Abstract: Our objective was to identify potential mechanisms by which prepartum diets high in linoleic acid increase calf weaning weight and heifer re-breeding performance. Thirty-six Angus and Hereford-Angus heifers that conceived on the same day to one sire were stratified by weight (436.1 ± 27.8 kg) and body condition score (BCS, 4.4 ± 0.7) and within strata assigned to receive a prepartum diet high in linoleic acid (S) or control (C) diet. Diets were isocaloric and isonitrogenous. Heifers were fed in pens of six from d -56 until calving. At calving, heifers were housed together and fed the same diet for the duration of the study. Blood samples were collected on d -56, -42, -28, -14, -10 to d 3, and twice weekly from d 0 (calving) to d 172 postpartum. Hip height, BW, BCS, and ultrasound fat depth were measured every 28 d. Heifers were exposed to one bull from d 126 to 175 and examined for pregnancy by ultrasound on d 172 and 209. Weight and BCS at calving did not differ (P > 0.10) between heifers fed S (455 kg, 5.8) or C (445 kg, 5.8). Calf birth weight and dystocia did not differ (P > 0.10), but calf vigor was greater (P < 0.05) in calves born to heifers receiving S. Weight, BCS, fat depth over the back and rump, hip height:weight, and serum leptin concentrations were not affected (P > 0.10) by treatment or treatment by day interaction. Pregnancy rate, postpartum interval, and interval from calving to conception did not differ (P > 0.10) between heifers fed S or C. Calf weaning weights adjusted for age and sex were similar between heifers fed S (241 ± 18 kg) vs C (232 ± 32 kg). We were unable to identify differences between heifers fed S vs C.