PSXII-28 - Effects of the nutritional plane before and after breeding on performance of different hair sheep breeds

Female hair sheep, 27 Dorper (DOR), 41 Katahdin (KAT), and 39 St. Croix (STC), were used to determine influences of nutritional planes before and after breeding on performance. There were 35 multiparous and 72 primiparous sheep, the latter 2.8±0.20 yr of age. Wheat straw [4% crude protein; dry matter (DM) basis] was consumed ad libitum and supplemented with approximately 0.25% initial body weight (BW) of soybean meal (SBM; Low) or a 1:3 mixture of SBM and rolled corn at 1% BW (High; DM). The supplementation period was 162 d, and with breeding of animals in 2 groups sequentially the pre-breeding period was 84 and 97 d and that after breeding began was 78 and 65 d. Wheat straw DM intake (1.75, 1.30, 1.57, 1.15, 1.80, and 1.38% BW; SEM=0.112), average daily gain (-46, 42, -44, 70, -47, and 51 g; SEM=7.3), and change in body condition score (-0.61, 0.36, -0.53, 0.27, -0.39, and -0.18 for DOR-Low, DOR-High, KAT-Low, KAT-High, STC-Low, and STC-High, respectively; SEM=0.058) were influenced (P < 0.05) by supplement treatment. Birth rate (66.7, 93.5, 84.6, 95.5, 82.8, and 100.0; SEM=9.83) and individual lamb birth weight (4.50, 4.61, 4.28, 3.98, 3.73, and 3.88 kg; SEM=0.201) were not affected by supplement treatment (P = 0.063 and 0.787, respectively), although litter size (0.92, 1.21, 1.17, 1.86, 1.12, and 1.82; SEM=0.221) and total litter birth weight (5.84, 5.74, 5.92, 7.52, 5.04, and 6.78 kg for DOR-Low, DOR-High, KAT-Low, KAT-High, STC-Low, and STC-High, respectively; SEM=0.529) were greater (P < 0.05) for High than for Low. In conclusion, although there was some compensation in wheat straw intake for the different levels of supplementation, SBM given alone rather than with cereal grain adversely affected body weight and condition and reproductive performance, the latter primarily through litter size but also via a trend for an effect on birth rate.