Using Corn Gluten Feed in Post-Partum Diets of Beef Cows to Optimize Reproductive Performance

Primiparous and multiparous Angus-Simmental cows were blocked by cow weight, BCS and age, and randomly assigned to one of three treatments 11 ± 11.5d post-calving: 1) silage-based total mixed ration (TMR; CON); 2) TMR with 3.3 kg/d DM CGF (MID); or 3) TMR with 6.7 kg/d DM CGF (HIGH), to evaluate the effects of feeding corn gluten feed (CGF) as a primary source of dietary energy on cow BW, body condition, and reproductive performance. Diets were formulated to be isocaloric and either meet, or exceed all other nutrient requirements (NRC, 2000) with a postpartum ADG of 0.17 kg/d. Blood samples were collected at 7d and 21d intervals from trial initiation until estrous synchronization for determination of plasma progesterone concentration as an indicator of resumption of cyclicity and for plasma urea nitrogen (PUN), respectively. Milk samples were collected at 62 ± 11.5d post-partum for composition analysis. A 5-d Co-Synch + CIDR protocol was started at 77 ± 11.5d and cows were bred by timed artificial insemination (TAI). Diameter of the largest antral follicle was determined at TAI via ultrasonography. Bulls were placed with cows 19d post-TAI for the remainder of the breeding season. Pregnancy diagnosis was accomplished via ultrasonography 38 and 112d post-TAI, respectively, for TAI and season pregnancy. Growth performance of male progeny was measured through trial termination. Data were analyzed using the GLIMMIX, MIXED and GLM procedures of SAS. Planned orthogonal contrasts were used to test treatment effects. Final cow BW (P ≥ 0.61), BCS (P ≥ 0.11), cyclicity (P ≥ 0.24), follicle diameter (P ≥ 0.42), TAI conception (P ≥ 0.42), and season pregnancy rates (P ≥ 0.97) were not different among treatments. PUN concentration did not differ (P ≥ 0.64) at trial initiation, but all treatments differed from each other (P = 0.01), on d-105 with HIGH the highest, MID intermediate, and CON lowest. No differences were seen in most milk components (P ≥ 0.26), however, milk fat tended to be higher (P ≥ 0.07) in the HIGH treatment when compared to other treatments. Calf birth weight differed with HIGH the highest, MID intermediate, and CON the lowest. Although, intermediate and end weights (60 and 101 ± 16.5 days of age, respectively) were not different (P ≥ 0.64). In summary, feeding high or intermediate levels of CGF to beef cows during early lactation did not alter cow reproductive performance.