Milk yield and composition from ewes fed raw soybeans and their lambs’ performance

Abstract

This trial aimed to evaluate the effects of increasing levels of raw soybeans on milk yield, composition, and fatty acid profile in ewes, and their lambs’ performance. Fifty-six Santa Ines ewes (63.9 ± 0.76 kg BW) were assigned to a randomized complete block design to receive one of the four diets containing 0 (CONT), 70, 140 or 210 g/kg DM of raw soybeans. Isonitrogenous diets (150 g/kg DM of CP) were composed of 400 g/kg DM of in natura sugarcane bagasse as roughage source and 600 g/kg DM of concentrate. The experiment lasted from 14 to 56 days of lactation. Once a week the ewes were separated from their lambs and milked mechanically. DMI (1.3, 1.3, 1.5 and 1.2 kg/day) and milk yield (1.0, 1.1, 1.1 and 1.0 kg/day) presented a quadratic effect (P < 0.05) including 0, 70, 140 or 210 g/kg DM of raw soybeans on diets, respectively. However, milk yield corrected for fat or fat and protein, as well as content of milk fat, protein, lactose and total solids did not differ. Short (C4-C12) and medium (C14-C16) chain fatty acids decreased, whereas long-chain (C ≥ 17) fatty acids increased linearly (P < 0.05) with raw soybeans supply. Conjugated linoleic acid (CLA; cis-9 trans-11 and trans-10 cis-12) increased (P ≤ 0.01) and the atherogenicity index decreased linearly (P < 0.05) with increasing levels of raw soybeans in the diet. Unsaturated:saturated ratio, saturated, unsaturated, monounsaturated and polyunsaturated fatty acids were similar among treatments. There was no difference in lambs’ performance in pre or post-weaning periods. Considering that the price of raw soybeans is generally lower than its meal, the inclusion of up to 140 g/kg DM of soybeans is recommended for increasing milk yield, with no detrimental effect on milk efficiency production, milk components and lambs’ performance. In addition, it is important to highlight that supplementation of up to 210 g/kg DM of raw soybeans made milk fat healthier for human consumption.