Performance of Heifers Grazing Bermudagrass Supplemented with Corn-Fish Meal, Corn-Soybean Meal, or Corn Gluten Feed

Abstract

A 3-yr study was conducted to determine the effect of supplementation on weight gain and reproduction of 240 fallborn crossbred heifers (80 per year; initial BW 252 ± 2 kg) grazing bermudagrass from July through November. Treatments were: no supplement (NS); 1.37kg ground corn plus 0.45kg of fish meal (CFM); 1.25kg of ground corn plus 0.57kg of soybean meal (CSBM); or 1.82kg corn gluten feed (CGF). There were three replicates of each treatment with two replicates located at one location and one replicate at another location during each year. The stocking rate was 3.7 head per ha. Treatment groups were rotated among pastures within site at 14-d intervals. At the end of the supplementation period, heifers were grouped across treatments within location and placed on ryegrass for a 60-d breeding period. Heifers were managed in these groups until calving. Forage quality decreased through the grazing period as did forage availability. Supplemental hay was offered when available forage was below 1100 kg/ha. Supplemented heifers gained an average of 0.51 ± 0.02kg compared to 0.27 ± 0.02kg for unsupplemented heifers (P<0.001). Heifers supplemented with CFM had higher (P=0.01) ADG (0.57 ± 0.02 kg) than heifers supplemented with either CSBM or CGF (0.48 ± 0.02 kg), and heifers supplemented with CSBM tended (P=0.07) to gain more weight (0.51 ± 0.02 kg) than heifers supplemented with CGF (0.45 ± 0.02 kg). Supplementation did not affect the number of heifers cycling at the beginning of the breeding season (P=0.50) or the number of heifers that were diagnosed pregnant after a 60-d breeding season (P=0.25). Heifers that received supplements prior to the breeding season were 20kg heavier at calving than non-supplemented heifers (P=0.01). These data indicate that although supplementation improved weight gain of the heifers grazing bermudagrass, the level of gain was not high enough to result in a significant increase in the number of heifers reaching puberty at the start of the breeding season or in an increase in the number of heifers pregnant.