PSII-17 Effect of supplementing algae to heifers during breeding and early gestation on growth and reproduction

Algae biomass provides a consistent source of docosahexaenoic acid (DHA), an omega-3 fatty acid, that could be used to alter hormonal profiles and improve reproduction of beef heifers. Eighty-eight Angus × Simmental heifers (427 ± 1.8 kg) were blocked by BW and allotted to 2 treatments (44/treatment, 4 pens/treatment, 11 heifers/pen). Control heifers were fed a diet that contained (DM basis) 52.8% mixed grass silage, 32% corn silage, and 15.2% concentrate. DHAgold (49% fat; 21.8% DHA; DSM Inc.) was included in the algae diet DM at 1.65%, replacing equal parts of corn and DDGS. Diets were formulated to contain 12% CP and 0.79 Mcal/kg NEg. Heifers were fed treatment diets from 54 d prior to the breeding season through the first trimester. Follicular fluid was collected on day 47 for hormonal analysis. Artificial insemination (AI) breeding was from d 55 to 98, after which open heifers were removed to 1 control and 1 algae pen and placed with a bull. The study ended on d 180. Performance data were analyzed using the MIXED procedure and conception data were analyzed using the GLIMMIX procedure of SAS. Dominant follicle diameter and follicular estrogen concentration were unaffected by the treatment (P ≥ 0.12). Follicular insulin-like growth factor-1 was greater in algae compared to control heifers (P = 0.03). During the pre-breeding period, algae heifers had lesser DMI (P = 0.006) compared to control heifers. Heifers supplemented with algae had greater ADG (P = 0.03) during the breeding period and BW tended to be greater for algae compared to control heifers on d 98 and 180 (P ≤ 0.07). First service conception rate did not differ between treatments (P = 0.67); however, second service tended (P = 0.08) and overall conception was (P = 0.03) lesser in algae compared to control heifers. These data suggest supplementing DHA-rich algae improved growth but decreased conception rates of beef heifers.