Lactation responses of dairy cows to whole-crop wheat or ryegrass silages

Feed intake and milk production responses to whole-crop wheat or ryegrass silages were measured in a replicated 3 × 3 Latin square experiment using nine (six multi- and three primiparous) Holstein cows. Each experimental period lasted for 3 weeks, with measurements performed in the last 7 days. Iso-nitrogenous diets contained (dry matter, DM, basis) 550 g kg−1 of a standard dairy cow concentrate (crude protein: 245 g kg−1 DM; starch: 255 g kg−1 DM) and 450 g kg−1 of one of the following silages: ryegrass (RGS; Lolium multiflorum Lam., cv. Promenade), Tigre wheat (TWS; Triticum aestivum L., cv. Tigre) and Arpan wheat (ARWS; T. aestivum L., cv. Arpan). All whole-plant forages were direct cut, on the same date, chopped to a length of ca. 5 cm and ensiled in bunker silos. Because RGS was harvested at a late stage of maturity, it contained 81 g crude protein kg−1 DM and 638 g neutral detergent fiber (NDF) kg−1 DM. The starch contents of TWS and ARWS were, respectively, 91 and 111 g kg−1 DM. The whole-crop wheat silages had higher acid detergent lignin contents and lower DM and NDF in sacco disappearance than RGS. The type of ensiled forage did not significantly affect feed intake or milk production and composition. Plasma urea concentration increased (P < 0.01) with the decrease in in sacco disappearance of silages, suggesting differences between dietary treatments in synchrony between N and energy supply to rumen microbes. This study showed no benefits of whole-crop wheat silages over late single cut ryegrass silage as base forage for lactating dairy cows.