Performance of bred heifers fed various supplements during gestation1

Professional Animal Scientist, Aug 2003 by Sanson, D W, Coombs, D F

Abstract

Three trials were conducted to evaluate the performance of heifers supplemented with various energy-based supplements while consuming a medium-quality warm-season hay during the last trimester of gestation. Trial 1 evaluated the effects of supplements that provided equal levels of CP while providing 0.1, 0.2, or 0.3% BW of corn. There were three replicates of each treatment in each of two years. Trial 2 evaluated the effects of supplements that provided equal levels of CP while providing 0, 0.15, or 0.3% BW of corn. Trial 3 evaluated the effects of feeding 1.4 kg of corn, rice bran, or soybean hulls. There was no attempt to correct for different intakes of CP. Heifers received medium-quality bahiagrass (Paspalum notatum) hay free-choice during the supplementation period. There was no effect of increasing the level of corn in Trial 1 or Trial 2 on heifer BW gain during the supplementation period (P>0.13). In addition, supplementation level prior to calving did not affect heifer BW change or condition score of cows from calving until weaning (P>0.11), had no effect on fall conception rates (P>0.43), and had no effect on calf birth BW or weaning BW (P>0.34). In Trial 3, heifers supplemented with corn or soybean hulls gained more BW (9 kg) than those supplemented with rice bran (P=0.003). There was no effect of supplementation on BW change after calving (P>0.45) or on fall pregnancy rates (P=0.62) in Trial 3. In addition, calf birth and weaning BW were not affected (P>0.52) due to supplements fed in Trial 3. Results suggest that increasing the level of supplemental corn from O to 0.3% of BW while maintaining equal supplemental CP intake will not improve gestating heifer performance when fed medium-quality hay. The data also indicates that soybean hulls have equal feeding value to corn when fed as a supplement to heifers consuming medium-quality hay.

(Key Words: Rice Bran, Soybean Hulls, Corn, Forage, Beef Heifers.)

Introduction

Supplementation of concentrate to livestock consuming forage is a common practice with many producers. Supplementation of ruminants is often utilized to stretch an existing forage supply or in an attempt to improve forage utilization to increase nutrient intake. Intake and digestibility of a forage are affected by the quality of the forage and the type and level of supplement used (Bowman and Sanson, 1996). Supplementation of cattle and sheep consuming mature, low-quality forages with cereal grains or cereal grain-oil seed meal combinations were reported to decrease DMI and fiber digestion (Elliott, 1967; Sanson and Clanton, 1989; Sanson, 1993; Matejovsky and Sanson, 1995). In contrast, improved BW gains and forage utilization have been reported with cattle and sheep consuming medium- to high-quality forage when supplemented with cereal grains (Lake et al., 1974; Goetsch et al., 1991; Paisley et al., 1994; Matejovsky and Sanson, 1995; Ruder et al., 1997).

Fibrous-type supplements were reported to increase utilization of low- and medium-quality forages (Martin and Hibberd, 1990; Sanson, 1993; Horn et al., 1995; Kunkle et al., 1995). In addition, level of supplementation also appears to have an effect on forage utilization and animal performance (Bowman and Sanson, 1996). The objective of these studies was to evaluate the effect of corn-based supplements fed at different levels and to compare corn, rice bran, and soybean hulls supplements with heifers in the last third of gestation consuming a medium-quality, warm-season hay.

Materials and Methods

Three trials were conducted to evaluate the performance of bred heifers supplemented during the last trimester of gestation with various supplements.

Trial 1. Angus x Brangus bred heifers were used in each of two years (72 in yr 1; 56 in yr 2) to evaluate the effects of level of corn supplementation during the last trimester on BW gain and subsequent cow and calf performance. Supplemental treatments were low, medium, and high corn (Table 1). Supplements were formulated and fed to provide equal levels of CP. Supplemental TDN intake increased with increased level of corn. In yr 1, heifers were randomized into nine groups of eight heifers within the breed of sire group so there were equal numbers of Angus-sired and Brangus-sired heifers in each group. In yr 2, heifers were randomized in six groups of nine heifers in a similar manner as in yr 1. Subsequently, groups were randomly assigned to receive one of the three supplemental treatments, resulting in three replicates of eight heifers in yr 1 and 2 replicates of nine heifers in yr2.

Trial 2. Seventy-two Angus x Brangus bred heifers were used in one year to evaluate the effects of level of corn/cottonseed meal supplementation during the last trimester on BW gain and subsequent cow and calf performance. Supplements were formulated and fed to provide equal levels of crude protein (Table 2). Supplemental TDN intake increased with increased level of corn. Heifers were randomized into nine groups of eight heifers within the breed of sire group so there were equal numbers of Angus-sired and Brangus-sired heifers in each group. Subsequently, groups were randomly assigned to receive one of the three supplemental treatments, resulting in three replicates of eight heifers.

Trial 3. Sixty-seven Angus x Brangus bred heifers were used in yr 1 and 81 similar heifers were used in yr 2 to compare supplementing corn, rice bran, or soybean hulls during the last trimester on BW gain of heifers prior to calving and subsequent cow and calf performance. Each year the heifers were randomized into nine groups (eight heifers in yr 1; nine heifers in yr 2) within the breed of sire group so there were equal numbers of Angus-sired and Brangus-sired heifers in each treatment. Subsequently, groups were randomly assigned to receive one of the three supplemental treatments (corn, rice bran, or soybean hulls), resulting in three replicates each of two years. Each of the three supplements was group-fed at a level equal to 1.4 kg per head per d. There was no attempt to correct for differences of protein intake. Hay was a medium-quality bahiagrass (11.6% CP, 57.4% IVDMD).

During the supplemental portion of all trials, heifers were maintained in 0.2-ha pens. Supplements were fed at 0800 h each day. Bahiagrass hay (Paspalum notatum) was offered free-choice during the supplemental period. Round bales were weighed prior to feeding in metal feeders and hay intake was estimated based on this weight. There was no attempt to account for hay that was wasted. Intake estimates were discontinued on the day that the first heifer calved; therefore, only the period when all heifers were consuming hay was included.