Effects of supplemental protein source on passage of nitrogen to the small intestine, nutritional status of pregnant ewes, and wool follicle development of progeny.

Rambouillet wethers, surgically fitted with ruminal and duodenal cannulas, were used to determine the influence of substituting soybean meal (SBM) with blood meal (BM) in grass hay diets (8.0% CP) on N flow to the small intestine. Treatments were arranged in a 3 x 4 Latin square design and included diets (10.6% CP) supplemented with SBM; 2/3 SBM:1/3 BM; 1/3 SBM:2/3 BM; or BM. Ruminal NH3 N concentration decreased linearly (P = .03) as BM replaced SBM; however, feeding BM did not affect (P > .10) the total N, microbial N, or nonammonia N flows to the small intestine. A second experiment was conducted to determine the influence of substituting SBM with BM on ewe BW and condition score changes, blood metabolite profiles, wool growth, and progeny wool follicle development. Thirty-two pregnant Targhee ewes fed a grass hay diet were allotted randomly to four groups (n = 8) and supplemented with either SBM; 2/3 SBM:1/3 BM; 1/3 SBM:2/3 BM; or BM. Soybean meal, BM, or their combinations provided 22 g of dietary CP daily. Dietary treatments had no influence on ewe BW (P = .40) or body condition score (P = .77) changes, and ewes gained 7.6 kg of BW during the 84-d experiment. Protein source did not influence (P > .10) serum protein, urea N, creatinine, glucose, or nonesterified fatty acid concentrations. Lamb wool follicle density per square millimeter and secondary:primary follicle ratios were 22.4 and 10.8, respectively, and were not different (P > .10) among dietary treatments. Compared with SBM, no advantages were detected for BM supplementation of grass hay diets in these studies.