Effects of offering different types of supplementation to spring calving dairy cows at grass in autumn.

The objective of this experiment was to compare alternative forages and concentrate as buffer feeds offered to spring-calving dairy cows in the autumn. Ninety Holstein-Friesian cows were balanced on calving date and milk yield (19.9 ± 1.5 kg/cow/day) and randomly assigned to one of 6 treatments; (i) 17.5 kg of grass DM allowance (LG), (ii) 24 kg of grass DM allowance (HG), (iii) LG + 4 kg concentrate DM (C), (iv) LG + 4 kg maize silage DM (M), (v) LG + 4 kg urea-treated processed whole crop wheat DM (UPWCW) and (vi) LG + 4kg fermented whole crop wheat DM (FWCW). Treatments were imposed from 13 September to 7 November 2004 (2 grazing rotations). Both LG and HG herds grazed separately while the 4 supplemented treatments grazed together, as a single herd. The supplementary forages were group fed from a diet feeder after morning milking. Concentrates were offered individually in the milking parlour during am milking. Herbage removal rate was 18.7, 15.0 and 14.4 kg/cow/day (s.d. 2.65 kg) for HG, LG and supplemented herds, respectively. Animals supplemented with concentrate (18.3kg/cow) had a significantly (P<0.001) higher milk yield compared to the HG (15.5kg), M (15.0kg) and UPWCW (14.9) treatments, which in turn had a significantly greater milk yield than LG (13.2kg) and FWCW (14.2 kg). Solids corrected milk (SCM) yield was significantly (P<0.001) greater for C (+2.3kg) than HG (14.9), which was greater than M (14.5), UPWCW (14.3) and FWCW (13.8kg /cow), the LG herd (12.6kg /cow) had the lowest SCM yield. Milk fat, protein and lactose concentrations, as well as body condition score (BCS) and liveweight were not significantly different across treatments. The rennetability of milk tended to be higher in treatments M and FWCW while it was poorest in C. There is a large solidscorrected milk production benefit to supplementing grazing cows, on a restricted grass allowance in late lactation, with concentrate. Supplementing with other forages gave smaller responses, while extra herbage allocation proved superior. [ABSTRACT FROM AUTHOR]