LAUSR

Objectives were to investigate the effects of late-gestation supplementation of Ca salts of fatty acids to beef cows on cow performance and offspring pre-weaning growth performance. One hundred and ninety fall-calving, Angus Simmental cows were ranked by BW, BCS, and age. Cows were randomly assigned into 12 endophyte-infected, tall fescue pastures (4 pastures/treatment; 15–16 cows/pasture). Cows were fed an isocaloric supplement with soybean hulls mixed with: whole-shelled corn (CON), 155 g/cow/d of EnerGII (SFA/MUFA), or 40 g/cow/d of Strata 120 g/cow/d of Prequel (PUFA) during the last 83 4.9 d of gestation. Cow BW and BCS were measured at the initial, middle point, and end of supplementation, as well as at breeding and weaning. Milk yield was evaluated by weigh-suckle-weigh technique at 675.0 d postpartum. Steers were weaned at 174 5.0 d of age. Growth performance, milk, and blood parameters were analyzed with MIXED and reproductive data were analyzed with GLIMMIX procedures of SAS. The BW and BCS of the cows were not different (P 0.19) from trial initiation through weaning. Birth BW of the steers was not different (P = 0.62). The AI or overall pregnancy rates were not different (P 0.88). There was no difference (P 0.12) in milk yield or components. However, C15:0 and total n-3 fatty acids in milk from dams supplemented with PUFA was greater (P 0.05) than CON, while SFA/MUFA was intermediate and not different than the others. There was no difference (P = 0.83) for weaning BW of the steers. In conclusion, late-gestation supplementation of Ca salts of PUFA had no effect on cow BW, BCS, or milk yield, but increased total n-3 fatty acids in milk. Neither birth BW nor weaning BW of steers were affected by maternal fatty acid supplementation.