High pasture allowance does not improve animal performance in supplemented dairy cows grazing alfalfa during autumn–winter

• We studied the effect of diverse alfalfa herbage allowance on dairy cow performance
• Highest dry matter intake are reached at medium and high herbage allowance
• High herbage allowance does not improve greatly milk production even though dry matter intake is higher

The aim of this study was to assess the effect of three alfalfa pasture herbage allowances on milk yield and composition during autumn–winter grazing season on early autumn calving dairy cows. Eighteen multiparous Holstein dairy cows were assigned to one of three treatments in a 3×3 Latin square design: low herbage allowance (14 kg DM/cow; LHA), medium herbage allowance (27 kg DM/cow; MHA) and high herbage allowance (41 kg DM/cow; HHA). Dry matter disappearance was lower at LHA although remained similar between MHA and HHA (P<0.05). However, as herbage allowance (HA) increased, lower grazing efficiencies (as the proportion of material removed) were registered (P<0.05). Total dry matter intake (DMI; kg/d) was also lowest for LHA and similar between the other two treatments (P<0.05). Milk yield, 4%FCM, milk fat (g/kg) and casein (g/kg) tended to increase from LHA to HHA (P<0.10). Cows at LHA tended to loss weight whilst cows at MHA and HHA had a tendency to increase BW according the season progressed (P<0.10). In summary, managing cows at HHA will allow cows to a slightly increase in individual milk production and BW gain but in detriment of herbage utilization and potentially, milk production per hectare.