Effects of Soybean Hull Additions to Molasses Supplements on Performance of Primiparous Beef Cows1

These studies evaluate the impact of supplemental soybean hulls on performance of primiparous beef cows and calves grazing pastures. In Exp. 1, 48 pregnant cows (385 ± 20 kg) were allocated to 12 pastures and assigned supplemental soybean hulls at 0, 1.6, or 3.2 kg DM/cow daily, in addition to a base supplement of 1.6 kg of liquid molasses and 0.8 kg of cottonseed meal. Cow BW and BCS were recorded every 28 d, and calf BW and cow milk production were evaluated on d 113 and 141. Pastures with cows receiving no supplemental soybean hulls had a greater (P < 0.05) decline in herbage mass (1,490 to 960 kg DM/ha) than pastures with cows receiving soybean hulls (1,640 to 1,250 kg DM/ha). Cow ADG (-0.12 to 0.22 kg/d), BCS change (-0.65 to 0), milk production (4.2 to 6.6 kg/d), and calf ADG (0.60 to 0.88 kg/d) increased linearly (P = 0.08) as the rate of soybean hull supplementation increased. In Exp. 2, 24 pregnant cows (362 ± 30 kg) were allocated to 12 pastures and received the same treatments as described in Exp. 1. On d 116, 16 cow-calf pairs were selected from the larger group and allocated randomly to 16 individual pens for evaluation of voluntary forage DMI. Supplementation treatments continued as previously assigned. Forage DMI decreased quadratically (P < 0.05; 1.95 to 1.58% BW) as the soybean hull supplementation level increased. Supplementation of primiparous cows with soybean hulls increased the BW of calves, increased the BCS of cows, and decreased the cow forage DMI.