Performance and intake of high-yielding Holstein cows offered a TMR either alone or with access to grazing for six hours per day

摘要

Grazing of lactating cows is a decreasing practice in Europe despite numerous potential benefits. In parts of Europe, farmers are required to graze all dairy cows for at least six hours per day during summer, but little is known about the effect on the performance of high-yielding animals. A study was undertaken to investigate the effects of the following treatments on high-yielding Holstein cow performance: continuous housing (C; control) with a total mixed ration (TMR), a six-hour grazing period directly after morning milking with TMR offered ad libitum when housed (EG; early grazing), a six-hour grazing period following morning milking with 75% of ad-libitum TMR when housed (RT; restricted TMR), or TMR access for one hour following morning milking,followed by a six-hour grazing period (DG; delayed grazing) then housed with TMR offered ad libitum. Total drymatter intake (DMI) was similar in C, EG and DG but lower in RT (26.9, 26.0, 26.7 and 23.8 kg DM/cow/d; P <0.001; SED 0.524). Milk yield was also lowest in RT, with mean values of 45.7, 44.2, 44.9 and 41.7 kg/cow/d in C, EG, DG and RT respectively (P =0.001; SED 0.993). High-yielding cows can be grazed for a six-hour period during the day with little impact on milk production provided TMR is unrestricted when housed.