Reason for the work

This study took place over the 2014-15 winter. It was part of a wider programme of work funded by AHDB Dairy. Although it reduces costs to overwinter replacement heifers outside, evidence was sought on the effects on the animals, in terms of their health, welfare, future milk production and fertility.

What was done

Three systems were compared: one group of heifers was grazed on kale with additional grass silage, another group was on deferred grazing, also with grass silage bales and a third, control, group was kept inside and fed a total mixed ration (TMR) of grass silage and concentrates.

All the animals were weighted each week. Measurements of body condition score, mobility and body hair length were made once a month. Around four weeks before calving those outdoors were moved indoors and after calving their milk production, milk composition and number of services to conception were recorded.

Figure 1. Heifers outwintered on kale

Figure 2. Outwintering on grass


Body condition score change was similar between all groups, with no significant difference for animals on any of the three systems.

  • The group outwintered on grass produced more milk in early lactation than the other two groups.
  • The housed group lost weight after calving, whereas the groups that had been kept outside gained weight after calving.


If planned carefully, out-wintering dairy replacement heifers is a cost-effective alternative to housing them, with no detrimental effects on early lactation or animal condition.

Using 2015 costs, the economic gain was around £178 per heifer for outwintering compared with the costs associated with winter housing and feeding.

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