Farm Table says:
What is the problem?
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 for either 2 or 6 weeks.
This study aim was to determine the dry matter intake (DMI) of early lactation grazing dairy cows allocated to one of four pasture allowances (PA) for either 2 or 6 weeks, and to establish if any carryover effects of treatments imposed during early lactation exist.
What did the research involve?
This full lactation study took place at Teagasc, Animal, and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork from 25 March to 27 November 2014. 96 early lactation dairy cows (41 primiparous and 55 multiparous) were blocked by breed (Holstein-Friesian, n=52; Jersey × Holstein Friesian, n=38; Norwegian Red, n=6), calving date (February 17 ± 15.5 days), parity (2.4±1.61), pre-experimental milk yield (22.6±4.20 kg), body weight (BW) (469±68.2 kg) and body condition score (BCS) (3.09±0.193) and from within block were randomly allocated to one of eight treatments in a randomised complete block design with a 4×2 factorial arrangement of treatments.
The cows were offered one of four PA (60, 80, 100 and 120% of intake capacity) for two durations of time (2 or 6 weeks). Pasture allocation was measured using pre-grazing herbage mass (>3.5 cm) and area (m2).
Cows assigned to the 2-week treatment were allocated a PA of 100% of intake capacity once the 2 weeks had elapsed (PA was the same as the 100×6 treatment); all 6-week cows were offered a 100% PA once 6 weeks of being allocated to their respective treatments elapsed.
What were the key findings?
The PA for the 100% treatment during week 1 of the experiment was 13.4 kg DM cow-1 day-1; this increased to 15.5 kg DM cow-1 day-1 by week 7.
During week 13 the PA was 16.0 kg DM cow-1 day-1 for all cows.
During week 6, there was a significant interaction between PA and duration.
During week 6 the DMI of the 120×6 treatment (14.6 kg DM cow-1) was significantly different to the 60×6, 80×6 and 100×6 treatments (10.7, 12.3 and 13.3 kg DM cow-1, respectively.
The quantity of pasture offered to dairy cows in early lactation significantly affected their DMI. However, when they returned to being offered 100% of their intake capacity no differences in DMI were observed indicating no carryover effects of previous treatments on this factor. There may be possible effects on body weight, behavior, reproduction and milk production, however.