Housing yearling dairy heifers outdoors during the winter period

Rachel M.   Boyle

There are doubts as to whether relatively slow growing dairy heifers can be kept outdoors without negative implications for their welfare and productivity.

In spite of their obvious importance in determining future production levels replacement heifers are often assigned the poorest housing conditions on Irish farms (O’Connell et al., 1993).   They are generally housed indoors, often in pens on slatted concrete floors, which has negative welfare implications and high economic costs.   Therefore, the objective of this experiment was to evaluate the behaviour, welfare, performance and climatic energy demand of yearling dairy heifers on two levels of nutrition kept either on an all-weather pad or indoors in cubicles.  

Ninety-six yearling dairy heifers, were blocked according to date of birth and body weight and assigned to one of four treatments in groups of eight: a) indoors (conventional free-access cubicles with rubber mats), silage only (Indoors low) b) indoors (as before), silage plus concentrate (Indoors high) c) outdoors (on an all-weather pad with wood-chip lying area and concrete feeding area), silage only d) outdoors (as before), silage plus concentrate (Outdoors high).   Instantaneous scan sampling and all occurrence sampling by direct observation were used to record behaviour.   All animals were inspected for skin lesions which were classified and scored according to severity prior to housing and at the end of the experiment.   The yearlings were weighed and body condition scored and feed intakes were recorded throughout the housing period.   Climatic energy demand and heat production was estimated for all animals based on the model by Higgins and Dodd (1989) and adapted from Hickey et al., (2002).

There was no effect of nutrition or housing treatment on time spent standing or lying, or on activity budgets (P>0.05).   However, a higher frequency of comfort, non-agonistic social and play behaviours were recorded outdoors.   In addition, more trips, slips and falls were recorded indoors (P<0.01).   There was no effect of nutrition on the proportion of heifers affected by different lesion categories (P>0.05).   However, outdoor yearlings had significantly lower limb lesion scores than indoor yearlings (P<0.001).   Significantly more yearlings indoors were affected by bare, hairless patches and adventitious bursa on the forelimbs. Yearlings outdoors had significantly lower average daily weight gains and body condition scores (P<0.05), which was partly explained by lower intakes.   However, their performance did not fall below recommended targets.   Furthermore, heat loss did not exceed heat production for any of the animals.

In accordance with Hanninen et al. (2003) indoor housing restricted the yearlings’ locomotory, comfort and social activities while animals on the out-wintering pad showed more normal and diverse behaviour patterns.   The fact that adventitious bursa were only recorded in the animals indoors is probably a reflection of the higher frequency of trips, slips and falls recorded in this treatment.   These lesions pose serious health and welfare concerns and reflect major inadequacies with the concrete flooring.   Although bare, hairless patches are not a serious health issue they indicate traumatic contact with housing fixtures and fittings.   This suggests inadequacies in housing design.   Yearlings outdoors had lower feed intakes compared to animals indoors, this was reflected in their lower average daily gains and body condition scores.   Nevertheless, yearlings outdoors had lower UFL (feed unit for maintenance and lactation, Irish Republic) intakes than that would be required to meet the daily liveweight gains they achieved compared to yearlings indoors.   This suggests that yearlings outdoors used their food more efficiently.   However, further research is required to elucidate the reasons for this.   Furthermore, their average daily gains were well within the recommendations by the Teagasc (Ireland) advisory service.   This may be due to the fact that yearlings outdoors did not experience cold stress on any of the days that weather recordings were made.

                 In conclusion, the out-wintering pad was associated with improvements to animal health and behaviour.   Furthermore, the system did not seriously compromise animal performance.   It is likely that these differences were driven more by the higher space allowances and better underfoot conditions associated with the out-wintering pad than to the outdoor environment per se.

References

1.   Hanninen, L. et al. (2003).   Resting behaviour, growth and diarrhoea incidence rate of young dairy calves housed individually or in groups in warm or cold buildings.   Acta Agric. Scand., Sect. A, Animal Science 53: 21-28.

2.   Hickey M.C., French P.   and Grant J.   (2002).   Out-wintering pads for finishing beef cattle: animal production and welfare.   Animal Science 75: 447-458.

3.   Higgons K.P.   and Dodd A.   (1989).   A model of the bioclimatic value of shelter to beef cattle.   Journal of Agricultural Engineering Research 42: 149-164.

4.   O’Connell J.M., Giller P.S.   and Meaney W.J.   (1989).   A comparison of dairy cattle behavioural patterns at pasture and during confinement.   Irish Journal of Agricultural Reearch 28: 65-72.