46 Use of soy hull as a supplement during late gestation and lactation for landrace hair sheep ewes in a forage-based system

Abstract Forage-based production systems can be limiting in providing adequate nutrition as the result of seasonal fluctuations in forage quality and quantity, especially during periods of increased nutritional demands such as late gestation and lactation. This study evaluated the use of an agro-byproduct supplementation (soy hull) to fill these demands. Barbados Blackbelly (BB) and St. Croix (STX) hair sheep ewes were bred November 1 in a 25-d breeding season in two single-sire groups to like breed sires, and initially managed as one group. Pregnant ewes (n = 36) were allocated, balanced by breed, parity and fetal numbers to either a corn/soybean (CS) or soy hull (SH) supplementation starting the last trimester of pregnancy. Ewes rotationally grazed predominantly fescue pastures subdivided into 6 sections (0.13 ha) using electro-netting (3 sections of 6 ewes per supplement type). Ewes were supplemented at either 0.75% BW (late gestation) or 1.5% BW (lactation) using a single group feeder per section. Ewes lambed on pasture and lambs were weaned at approximately 63 d. Lambs had access to the supplement provided to their dams. Data were collected on ewe BW changes and reproductive performance, and analyzed in a model with supplement type and breed as main effects. Results are presented as LSM. Supplement type had no effect on ewe prepartum (54.7 kg), postpartum (47.3 kg) and weaning BW (44.7 kg), whereas BW was consistently heavier in STX than BB ewes. Ewe late gestation (61 g/d) and lactation ADG (-51 g/d) were not affected by supplement type though breeds differed (P 0.01) in lactation ADG (BB: -14 vs STX: -78 g/d). Lambing performance was also not affected by supplement type with 1.97 lambs born live, and 1.69 lambs weaned per ewe. There was a supplement type by breed interaction (P 0.05) for number of lambs weaned with STX ewes receiving SH having a larger litter size at weaning than ewes receiving CS (1.40 vs. 2.10 lambs per ewe) with no difference in BB ewes (1.71 vs. 1.50 lambs per ewe, respectively). Neither litter birth (6.14 kg) and weaning weights (19.9 kg) nor litter ADG (233 g/d) were affected by supplement type. Litter BW was significantly greater (P 0.01) in STX than BB (6.85 vs 5.18 kg), but not different at weaning. Lamb birth and weaning weights were not affected by supplement type, though preweaning ADG tended (P 0.1) to be greater in CS than SH (162 vs. 142 g/d). Data indicate that substituting SH for a more traditional corn-based supplement in landrace hair sheep ewes managed in a pasture-based system did not affect ewe growth, reproductive performance, and lamb performance. Agro-byproduct supplementation should be explored further for use in sustainable, forage-based sheep production systems.