Impact of roughage feeding and pasture strategies on health traits of heifers and cows (Work Package 4)

Summary

The objective of the present study was to investigate the possible long-term effects of transhumance of heifers during summer on mountain upland pasture and non-silage feeding of the dairy heifers on the fertility, milk productivity, health and longevity of subsequent cows. The study took place in the Massif Central area (France) where traits of milk performance testing were collected from four groups of 10 conventional low input farms rearing Holstein or Montbéliarde cows. In these farms, animals born from 2005 onwards and calving until end of 2019 were considered. After plausibility checks, the lactation data from 3465 and 4641 cows were used to study the influence of 1/ heifer summer transhumance on mountain pasture (vs on-farm pasture of heifers) and 2/ heifer silage feeding (vs only hay) respectively.
Animals that were on a mountain pasture during the heifer-rearing period had similar fertility and longevity to those that were reared on-farm but contrary to Holstein cows, Montbéliarde cows had a lower milk yield on first lactation. Heifers reared on mountain pasture had more frequent articular diseases. Heifers that were fed silage in comparison to hay had a similar fertility and milk production during their first lactation but their longevity was higher which explains their higher cumulated milk production over their whole career. Heifers fed with silage had increased probabilities to have subclinical ketosis and lower probabilities to have subclinical acidosis.