The effect of early lactation concentrate build-up strategy on milk production, reproductive performance and health of dairy cows

• The study was undertaken on five dairy farms, and involved 385 cows.
• Two concentrate build-up strategies imposed - ‘Immediate’ or ‘Delayed’.
• Delayed build-up strategy reduced daily milk during first five weeks of lactation.
• No effect observed on milk yield or composition over the first 305 days of lactation.
• No effects observed on overall fertility performance or on the numbers of cows culled.

The objective of this study was to examine the effect of two early lactation concentrate build-up strategies on cow performance, fertility and health. The study was undertaken on five Northern Ireland dairy farms, and involved 385 multiparous Holstein-Friesian cows. Cows were allocated to either an ‘Immediate’ or ‘Delayed’ concentrate build-up strategy postpartum. All cows were offered a ‘basal’ diet comprising forage and concentrates (mean, 7.4 kg concentrate/cow/day), with a target crude protein (CP) and starch concentration of 145 and 170 g/kg dry matter (DM), respectively. An additional 7.0 kg of concentrate (mean across the five farms) was then introduced into the diet of each cow, at an incremental rate of approximately 0.5 kg/day, over days 1–14 of lactation (‘Immediate build-up’) or over days 21–35 of lactation (‘Delayed build-up’), with the target CP and starch concentration of the total diet being 175 and 200 g/kg DM, respectively. While average daily milk yield and fat-plus-protein yield was reduced (P<0.05) during weeks 2 to 5 of lactation with the Delayed concentrate build-up strategy, treatment had no effect on milk yield, milk composition or milk fat and protein concentration over the first 305 days of lactation. Cows on the Delayed build-up strategy produced milk with a higher somatic cell score (P<0.05), while no treatment×time interactions were observed on body condition score during the experimental period. Conception rate to first service was higher with the Delayed build-up strategy (P=0.047), although treatment had no effect on conception to first and second service, calving interval and cows confirmed pregnant during the study (P>0.05). The Delayed build-up strategy tended (P=0.051) to reduce the incidence of fertility related health issues within the first 30 days of lactation, but increased the incidence of mastitis (P<0.05). Treatment had no effect on any other health measures, the reasons that cows were culled, or the stage of lactation when cows were culled (P>0.05). Although concentrate build-up strategy had short-term effects on milk yield and fertility in early lactation, no long term benefits in performance, fertility, health or survival were observed with the Delayed Build-up strategy.