Effects of the Level and Composition of Concentrate Supplements before Breeding and in Early Gestation on Production 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 the nutritional plane before breeding and in early gestation on feed intake, body weight, body condition score, body mass indexes, blood constituent concentrations, and reproductive performance. There were 35 multiparous and 72 primiparous sheep, with initial ages of 5.6 ± 0.25 years and 1.5 ± 0.01 years, respectively (average overall initial age of 2.8 ± 0.20 years). Wheat straw (4% crude protein; dry matter [DM] basis) was consumed ad libitum and supplemented with approximately 0.15% initial body weight (BW) of soybean meal (LS) or a 1:3 mixture of soybean meal and rolled corn at 1% BW (HS; DM). The supplementation period was 162 days, with the breeding of animals in two sets sequentially, with the pre-breeding period 84 and 97 days, and that after breeding began at 78 and 65 days, respectively. Wheat straw DM intake (1.75, 1.30, 1.57, 1.15, 1.80, and 1.38% BW; SEM = 0.112) was lower (p < 0.05), but average daily gain (-46, 42, -44, 70, -47, and 51 g for DOR-LS, DOR-HS, KAT-LS, KAT-HS, STC-LS, and STC-HS, respectively; SEM = 7.3) was greater (p < 0.05) for HS than LS treatment during the supplementation period. Additionally, changes in body condition score during the supplementation period (-0.61, 0.36, -0.53, 0.27, -0.39, and -0.18; SEM = 0.058), and changes in body mass index based on height at the withers and body length from the point of the shoulder to the pin bone (BW/[height × length], g/cm2) from 7 days before supplementation (day -7) to day 162 were -1.99, 0.07, -2.19, -0.55, -2.39, and 0.17 for DOR-LS, DOR-HS, KAT-LS, KAT-HS, STC-LS, and STC-HS, respectively; (SEM = 0.297) were affected by supplement treatment. All blood constituent concentrations and characteristics addressed varied with the day of sampling (-7, 14, 49, 73, and 162) as well as the interaction between the supplement treatment and the day (p < 0.05), with few effects of interactions involving breed. 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-LS, DOR-HS, KAT-LS, KAT-HS, STC-LS, and STC-HS, respectively; SEM = 0.529) were greater (p < 0.05) for HS than for LS. In conclusion, although there was some compensation in wheat straw intake for the different levels of supplementation, soybean meal given alone rather than with cereal grain adversely affected BW, BCS, BMI, and reproductive performance, the latter primarily through litter size but also via a trend for an effect on the birth rate. Hence, the supplementation of low-protein and high-fiber forage such as wheat straw should include a consideration of the inclusion of a feedstuff(s) high in energy in addition to nitrogen.

Effects of Nutritional Plane at Breeding on Feed Intake, Body Weight, Condition Score, Mass Indexes, and Chemical Composition, and Reproductive Performance of Hair Sheep.

This study was conducted to assess effects of the nutritional plane before and during breeding on feed intake, body weight (BW) change, reproductive performance, body condition score (BCS), body mass indexes (BMI), and body composition of three breeds of hair sheep. Twenty-five Dorper, 27 Katahdin, and 33 St. Croix ewes were allocated to groups and treatments based on initial BW and age. Supplementation treatments were soybean meal fed at 0.16% BW (LS) and a mixture of 25% soybean meal and 75% ground corn given at 0.8% BW (HS; dry matter basis) for 88 to 102 days including 17 days after breeding. Wheat straw intake (% BW) was greater (p < 0.01) for LS than for HS. Average daily gain and BCS change were similar among breeds, but both were greater for HS vs. LS. Birth rate, litter size, total litter birth weight, gestation length, and number of services were similar among breeds (p > 0.05), although individual lamb birth weight was lower for St. Croix than for Katahdin (p < 0.05). None of these reproductive variables were influenced by treatment or the breed × treatment interaction (p > 0.05). There were no breed differences in whole body concentrations of water, fat, protein, ash, or energy in week 0 or 4, but in 8 week concentrations of water, protein, and ash were greatest among breeds for St. Croix (p < 0.05) and levels of fat and energy were lower for St. Croix than for Dorper (p < 0.05). In week 8, total amounts and concentrations of fat and energy were greater for HS vs. LS and those of water, protein, and ash were less for HS (p < 0.05). There were interactions (p < 0.05) between treatment and period in blood concentrations of cholesterol and non-esterified fatty acids and between breed, treatment, and period in level of triglycerides and total antioxidant capacity. The concentration of cortisol was greater for HS vs. LS (p < 0.05). In conclusion, supplementation did not influence reproductive performance despite differences in BW and BCS change, which may be due to the initial moderate BCS and greater wheat straw intake for the LS treatment.