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Objectives were to investigate the effects of supplementing Ca salts of fatty acids to beef cows during late gestation on the pre-weaning growth performance and gene expression of steer progeny. Ninety-six fall-calving, Angus x Simmental cows (BW = 601±76 kg) were randomly assigned into 8 pastures (4 pastures/treatment; 12 cows/pasture), supplemented soyhulls mixed with 80 g/cow/d Strata + 80 g/cow/d Prequel (PUFA, rich in linoleic acid, eicosapentaenoic acid, and docosahexaenoic acid) or 155 g/cow/d EnerGII (SFA/MUFA, rich in palmitic and oleic acids) for 76.5±6.0 d prepartum. Cow/calf pairs were comingled after calving. Biopsies of Longissimus dorsi (LD) and subcutaneous adipose were taken at birth and 3 wk before weaning (186±6 d). The data were analyzed using the MIXED procedure of SAS. Supplementing PUFA increased (P < 0.01) cow plasma eicosapentaenoic acid and docosahexaenoic acid at midpoint of supplementation. At birth, PUFA steers had greater (P < 0.05) plasma EPA and lower (P < 0.01) plasma linolenic acid and oleic acid than SFA/MUFA steers. Weaning BW and pre-weaning ADG of the SFA/MUFA steers tended (P < 0.07) to be greater than PUFA steers. SFA/MUFA steers had increased (P = 0.04) expression of Zfp423 in adipose. There tended to be a treatment×time interaction (P = 0.06) for expression of Myf5 in LD; expression of Myf5 was greatest in SFA/MUFA steers at birth. There was a treatment×time interaction (P = 0.05) for expression of Pax7; expression was greater in SFA/MUFA steers at birth than any treatment at weaning. There were treatment×time interactions (P < 0.01) for expression of Myh7 and C/EBPβ in LD; expressions were greatest in PUFA steers at weaning. Supplementing Ca salts of PUFA to beef cows during late gestation altered plasma fatty acid profile of cow and calf, affected gene expression, and decreased offspring growth performance.

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.