Soy hulls as a replacement for maize in lactating dairy ewe diets with or without dietary fat supplements

Digestion and performance of lactating dairy ewes fed diets with soy hulls (SH), with or without dietary fat supplements, as a replacement for maize in concentrate diets were evaluated in digestion and milk performance trials. In the digestion trial, three fistulated wether sheep were used in a 3 x 3 Latin square experimental design. The diets consisted of 400 g hay+600 g concentrate with 60% maize (control treatment), or 60% soy hulls (SH treatment), or 60% soy hulls+5% soybean oil (SHF treatment). Diets' DM and OM digestibilities were similar among treatments, while the replacement of maize by SH caused a significant reduction on CP, EE, and NFE digestibilities, and a significant increase on NDF and ADF digestibilities. The addition of 5% soybean oil to SH concentrate had similar effect on nutrients digestibility, as SH. Concentrates DM and CP degradabilities, pH values and VFA concentrations in rumen liquor were also similar among treatments. In the performance trial, 45 lactating ewes were used, which were fed daily, for 7 weeks, 800 g hay+1200 g concentrates of the type as in the digestibility trial. Milk yield and FCM yield increased by 3 and 33% (p<0.001), and by 16 (p<0.001) and 36% (p<0.001) for SH and SHF diets, respectively. SH treatment increased (p<0.001) milk fat, protein and NFS content, but SHF diet reduced them, compared to control treatment. However, mill; fat, protein, lactose and NFS production (in g day(-1)) was higher for the SHF diet, followed by SH and then by the control diet. All ewes gained weight during the experimental period, but the BW change was not significant among treatments. The results showed that SH can replace cereal grains in lactating ewe diets, and minimize the milk fat-depressing effects of grain-based diets. (C) 1998 Elsevier Science B.V.