Performance of growing lambs fed grass silage with raw or extruded soybean or canola seeds

Abstract

Thirty-two Outaouais male lambs were assigned to a completely randomized design with a 2 x 2 factorial arrangement of treatments to determine the effect of extrusion of full fat seeds on performance and carcass quality. Raw (NE) and extruded (EX) isonitrogenous and isoenergetic mixtures of barley and either full fat soybean (SB) or canola seed (CA) were fed at a daily rate of 424 and 400 g, respectively. Lambs were fed silage ad libitum from 20 to 43 kg. Intakes of silage DM and total DE were similar among treatments. The ADG and concentration of total polyunsaturated fatty acids (FA) in muscle were higher for lambs fed EX than NE seeds and the effect was greater for SB than CA mixture; this tended (P = 0.06) to result in an interaction between seed and extrusion for polyunsaturated FA in muscle. Similar trends were observed for feed efficiency. This could reflect the response to heat treatment as extrusion significantly reduced N degradability of SB mixture but had no effect on that of CA mixture. Digestibilities of DM, N, and energy were higher (P < 0.10) for lambs fed SB than for lambs fed CA mixture and extrusion had no effect. Data suggest that extrusion of seeds can be used to improve performance of lambs fed a high forage diet and modify FA composition of the carcass.