THE WELFARE OF EXTENSIVELY MANAGED DAIRY-CATTLE - A REVIEW

In contrast to intensive dairying practices in many Northern Hemispher e countries, dairy cattle in many countries in the Southern Hemisphere , such as Australia and New Zealand, are grazed outdoors all year roun d. Outdoor farming has a more favourable welfare image largely because of the freedom of the animals to perform a wide range of species-spec ific behaviours and possibly because of the perception of less stress and fewer health problems. However, there are a number of practices th at have the potential to adversely affect the welfare of cows and calv es. This review identifies some of the main animal welfare issues in e xtensive dairy production. Induced calving can result in high calf mor tality rates (rates vary from 0 to 38.5%), particularly if induction o ccurs prior to 270 days of gestation, and in slower and less efficient uptake of colostral immunoglobulins. Also, the ability of cows to res pond to stressors may be impaired due to long-term suppression of endo genous cortisol. Lameness is conservatively estimated to range between 5.5 and 14% of cows, although one estimate is as high as 60% of cows on an annual basis. Lameness may be affected by a number of factors in cluding the type and maintenance of the farm track, the patience of th e stockperson in handling the cows and the herd size. Transport of you ng calves can result in a 50% incidence of bruised stifles and mortali ty rates greater than 20% following transport, particularly when calve s are transported younger than 14 days old. While calves are relativel y cold sensitive at birth, both heat and cold can affect the immune sy stem of calves and adversely affect growth rate of neonatal calves. Th e adult cow is adversely affected more by heat than by cold with effec ts on both reproduction and lactation; some of the adverse effects on lactation can be obviated by the provision of shade. Nevertheless, a c limatic factor often associated with cold is wet weather and this can contribute to lameness. The behaviour of the stockperson (e.g. impatie nce) may be associated with lameness and there is some limited evidenc e to indicate that cows that are less fearful of humans may have bette r milking behaviour and milk production. Tail-docking can adversely af fect fly-avoidance behaviour to such an extent that grazing and rumina tion are disturbed. Disbudding appears to be associated with pain resp onses that can be obviated by local anaesthesia. Some biotechnological manipulations currently include procedures such as bovine somatotroph in, superovulation, embryo transfer and genetic engineering.