Feed Intake and Live Weight Gain of Hereford Bulls Offered Diets Based on Whole-Crop Barley and Whole-Crop Wheat Silages Relative to Moderately Digestible Grass Silage with or without Protein Supplementation

The present experiment was conducted to study the performance of Hereford bulls offered diets based on whole-crop barley (WCB) and whole-crop wheat (WCW) silages relative to a moderately digestible grass silage (GS)-based diet with or without rapeseed meal (RSM) supplementation. The experiment comprised 30 bulls and a 3×2 factorial design was used. The bulls were offered silages ad libitum. In all forage diets (WCB, WCW, GS) the concentrate used was either rolled barley alone or rolled barley plus RSM. The amount of the concentrate supplementation was 37 g/metabolic live weight/animal/day for all treatments. The crude protein (CP) content of barley was 126 g/kg dry matter (DM) and the CP content of the concentrate increased 23% with RSM supplementation. Average live weight gains (LWG) for the GS, WCB and WCW feedings were 1411, 1331 and 1181 g/d, respectively. Differences in diet digestibility and energy intake probably explain the differences in LWG among the forage types. RSM supplementation increased both silage and total DM intake in the WCB and WCW feedings but not in the GS feeding. Furthermore, RSM supplementation increased LWG 7 and 17% in the WCB and WCW feedings, respectively, but only 2% in the GS feeding.