The effect of pasture allowance offered for different time durations on the dry matter intake of dairy cows

摘要

Milk quota abolition will increase herd size resulting in greater deficits in spring grass availability. 96 early lactation grazing dairy cows were assigned to one of four pasture allowances (PA; 60,80, 100 and 120% of intake capacity) for either 2 or 6weeks. All cows were allocated a 100% PA during the carryover period. Dry matter intake (DMI) was estimated during weeks 2,6 and 13. During week 2, there was no difference in DMI between the 100 and 120% allowances (13.7 kg DM cow~(-1)) but their DMI wassignificantly greater than the 60 and 80% allowances (10.4 and 11.5 kg DM cow~(-1), respectively), which were also significandy different to each other. During week 6, there was a significant interaction between PA and duration. Cows assigned to the 2-week treatment had similar DMI (13.9 kg DM cow~(-1)). The 120x6 treatment (14.6 kg DM cow~(-1)) was significantly different to the 60x6, 80x6 and 100x6 treatments (10.7,12.3 and 13.3 kg DM cow~(-1), respectively). There was no difference in DMI between the 80x6 and the 100x6 treatments (12.8 kg DM cow~(-1)), which were both different to the 60x6 treatment (10.7 kg DM cow~(-1)). During week 13, there was no effect of treatment on DMI (15.1 kg DM cow~(-1)). Differences in DMI were observed during the experimental period, but there was no effect of treatment on DMI during the carryover period. In conclusion, varying the PA of early lactation dairy cows from 60 to 120% of intake capacity for 2 or 6 weeks produced no carryover effects in terms of DMI.