Effect of rate of substitution of processed, urea-treated whole-crop wheat for grass silage on the intake, milk production and diet digestibility in dairy cows and ruminal metabolism in vitro

Abstract

The effect of rate of substitution of processed, urea-treated whole-crop wheat (pWCW) for grass silage on intake, performance and whole-tract digestibility was evaluated using 44 dairy cows. Cows received 10.5 kg of concentrates per day and one of the following forage mixtures (dry matter (DM) basis): grass silage alone (W-0); 0.75 grass silage, 0.25 pWCW (W-25); 0.5 grass silage, 0.5 pWCW (W-50) or 0.25 grass silage, 0.75 pWCW (W-75). Forage DM intake increased linearly with inclusion rate of pWCW from 9.7 kg DM per day in cows fed W-0 to 14.6 kg DM per day in W-75. By contrast, milk and protein yield (kg/day) were higher (P , 0.05) in cows receiving W-25 compared with W-0, but there was no effect (P . 0.05) of treatment on fat yield (kg/day). From week 11 of the experiment onwards, body condition score increased with rate of inclusion of pWCW ( P , 0.05). Whole-tract apparent digestibility of organic matter (OM) and fibre (kg/kg), decreased linearly with rate of inclusion of pWCW. Assuming a constant digestibility of starch in the other diet components, the apparent digestibility of starch in pWCW was 0.95 kg/kg and was not affected by rate of inclusion (P . 0.05). Four continuous culture vessels were used to determine the effect of rate of inclusion of pWCW on ruminal metabolism in four periods, each of 14 d duration with sampling conducted on days 9 to 14. Vessel ammonia concentration increased linearly ( P , 0.05) with rate of inclusion of pWCW whilst mean pH tended (P ¼ 0.06) to decrease. The ratio of acetate to propionate increased from 2.5 in vessels receiving W-0 to 3.2 in those receiving W-75 (P , 0.001). There was no effect (P . 0.05) of treatment on digestibility (g/g) of OM, fibre or starch or microbial protein flow (g/day). It is concluded that forage DM intake increased linearly with rate of inclusion of pWCW, but there was no further improvement in milk yield from inclusion rates above 0.25 of the forage DM, with body condition score increasing instead. Increasing the inclusion rate of pWCW resulted in a more ketogenic volatile fatty acid profile but did not affect the efficiency of microbial protein synthesis when determined in vitro.

Effects of maturity stage and feeding strategy of whole crop barley silage on intake, digestibility and milk production in dairy cows

“…Generally, whole crop cereal silage is considered to have lower digestibility and energy contents than that of high-quality grass silage (Hameleers,1998). The digestibilities of OM and NDF in the B1, M1 and M2 diets in the present experiment were similar to values (digestibility OM = 786 g kg − 1 , NDF = 720 g kg − 1 ) reported by Sinclair et al (2007) for a diet with similar concentrations of forage (grass silage only, ME = 10.9 MJ) and concentrate. Replacing a grass silage of 11 MJ with WCBS at heading is therefore possible, as long as the protein requirements of the dairy cows are met.…”

“…They reported milk production similar to that obtained when the cows were fed diets with only grass silage as forage, provided that the WCBS proportion of the diet did not exceed 0.40 of forage DM (Bertilsson and Knicky, 2005;Ahvenjärvi et al, 2006). In another study, milk production was similar to the control treatment (grass silage only) when cows were fed late harvested, urea-treated whole crop wheat at 0.75 of forage DM (Sinclair et al, 2007). The aim of this experiment was to investigate the effect of maturity stage at harvest of WCBS, ranging from heading to early dough stage, on feed intake, diet digestibility and milk production by dairy cows.…”

Effects of inclusion of whole-crop pea silages differing in their tannin content on the performance of dairy cows fed high or low protein concentrates

“…It is has been demonstrated that mixing a second forage with grass silage results in an increase in DM intake (Phipps et al, 1995;Sinclair et al, 2007). Similarly, Salawu et al (2002), and Adesogan et al (2004), reported that midlactation cows fed pea-wheat intercrop silages had a forage DM intake that was higher than those fed grass silage alone.…”

Dietary starch concentration alters reticular pH, hepatic copper concentration, and performance in lactating Holstein-Friesian dairy cows receiving added dietary sulfur and molybdenum

“…The antagonist supplemented diets were formulated to contain a total dietary concentration of approximately 3. diets were formulated to support a milk yield of approximately 38 kg/d according to Thomas (2004). Dietary ingredients were mixed using a forage mixer calibrated to ± 0.1 kg, with the resulting TMR being fed through roughage intake feeders (Hokofarm, Marknesse, Netherlands), fitted with an automatic weighing and animal identification system calibrated to ± 0.1 kg (Sinclair et al, 2007). Fresh feed was offered at 0900 h daily at 105% of the previous recorded intake, and refusals collected three times per week on a Monday, Wednesday and Friday.…”