Abstract Pasture-based sheep production may require supplementation during periods of reduced forage quality and quantity, and periods of high nutritional demands. This experiment compared soy hull to a more traditional corn-based supplement for hair sheep ewes managed in a pasture-based accelerated mating system. Growth performance and fitness of the lambs was evaluated. Ewes (Barbados Blackbelly and St. Croix; 30 -36 per season) were bred in March, July, and November in 25-d breeding seasons in two single-sire groups to like breed sires, and subsequently managed as one group. Pregnant ewes (30-36 per season) were allocated balanced by breed, parity and fetal numbers to either corn/soybean meal (CS) or soy hull (SH) supplementation starting the last trimester. Ewes were supplemented at either 0.75% BW (gestation) or 1.5% BW (lactation). Ewes rotationally grazed or were provided hay on pastures divided into 6 sections (0.13 ha; 3 sections of 5 - 6 ewes per supplement type). Lambs were born on pasture, had access to the supplement provided to their dams and were weaned around 9 wk. Lamb birth and weaning weights were recorded, and fecal egg counts (FEC), packed cell volume (PCV), and body condition (BC) were determined at weaning. Data (n = 175) were analyzed in a model with supplement type, mating season, breed, sex, and birth type as main effects. FEC were log-transformed before analysis (means reported). Lambs with access to the CS tended (P 0.1) to have a higher 60-d adjusted weaning weight (11.8 vs. 11.5 kg), pre-weaning ADG (148 vs. 135 g/d), and BC (1.82 vs. 1.64) compared to SH lambs. There was no effect of supplement type on FEC and PCV. Mating season had a significant P 0.01) effect on lamb weaning weight (April: 12.4 kg; August: 11.4 kg; December: 10.5 kg) and pre-weaning growth and ADG was higher (P 0.001) in April-born (155 g/d) compared to December-born lambs (126 g/d), with August-born lambs being intermediate (144 g/d). There was a supplement type x season interaction (P 0.05) for weaning weight and ADG with lower growth performance in SH-supplemented lambs in July, and increased growth in CS-supplemented lambs in November. Lamb survival to weaning tended (P = 0.08) to be higher in SH-supplemented (92.1%) than CS-supplemented (83.7%) lambs. There was no effect of season on BC, FEC, and PCV. St. Croix lambs had higher (P 0.05) birth and weaning weights, but not pre-weaning ADG than Barbados Blackbelly lambs, and lower PCV (P 0.05). There was no effect of breed on FEC. The season by supplement type interaction suggested an influence of forage environment on the supplementation response. Soy hull supplementation caused a nominal reduction in pre-weaning growth of lambs, but improved in lamb survival and presents a viable supplement in a forage-based production system.
Wildeus et al. (2026) studied this question.