Influences of supplemental fat, differing in fatty-acid composition, on performance, lactation, and reproduction of beef cows

Angus × Simmental, fall-calving cows (n = 480) were allotted to 1 of 4 supplements containing whole raw soybeans (SY), OmegaFlax (FLX), Energy Booster 100 (EB), or corn-soybean meal (CON). The SY, FLX, and EB supplements were formulated to have the same concentration of crude fat. The FLX, EB, and CON supplements were formulated to be isonitrogenous. Cows were blocked by age (2 groups) and randomly assigned to treatments before calving (36 ± 0.6 d prepartum). The cows were fed 1.81 kg of DM/d of respective supplement for 108 d. There were no differences in BW or BCS change in any contrasts. There were no differences in percentage of cows cycling before the breeding season or first-service AI conception for any of the contrasts. The SY-supplemented cows had lower (P = 0.01) overall pregnancy rate compared with FLX-supplemented cows and tended (P = 0.06) to have lower overall pregnancy rates compared with EB-supplemented cows. There was no difference in overall pregnancy for SY, FLX, and EB versus CON (P = 0.81). The SY-supplemented cows tended (P = 0.06) to have greater AI embryonic loss than did EB-supplemented cows. Fat supplementation during the pre- and postpartum period did not affect cow BW or reproductive performance compared with cows fed control supplement. Cows fed supplement containing soybeans as the fat source had poorer reproductive performance than did cows fed supplements containing OmegaFlax (flaxseed) or Energy Booster 100 (hydrolyzed animal fat) as the fat source.