THE WELFARE OF EXTENSIVELY MANAGED DAIRY-CATTLE - A REVIEW

In contrast to intensive dairying practices in many Northern Hemisphere countries, dairy cattle in many countries in the Southern Hemisphere, such as Australia and New Zealand, are grazed outdoors all year round. Outdoor farming has a more favourable welfare image largely because of the freedom of the animals to perform a wide range of species-specific behaviours and possibly because of the perception of less stress and fewer health problems. However, there are a number of practices that have the potential to adversely affect the welfare of cows and calves. This review identifies some of the main animal welfare issues in extensive dairy production. Induced calving can result in high calf mortality rates (rates vary from 0 to 38.5%), particularly if induction occurs prior to 270 days of gestation, and in slower and less efficient uptake of colostral immunoglobulins. Also, the ability of cows to respond to stressors may be impaired due to long-term suppression of endogenous 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 including the type and maintenance of the farm track, the patience of the stockperson in handling the cows and the herd size. Transport of young calves can result in a 50% incidence of bruised stifles and mortality rates greater than 20% following transport, particularly when calves are transported younger than 14 days old. While calves are relatively cold sensitive at birth, both heat and cold can affect the immune system of calves and adversely affect growth rate of neonatal calves. The adult cow is adversely affected more by heat than by cold with effects on both reproduction and lactation; some of the adverse effects on lactation can be obviated by the provision of shade. Nevertheless, a climatic factor often associated with cold is wet weather and this can contribute to lameness. The behaviour of the stockperson (e.g. impatience) may be associated with lameness and there is some limited evidence to indicate that cows that are less fearful of humans may have better milking behaviour and milk production. Tail-docking can adversely affect fly-avoidance behaviour to such an extent that grazing and rumination are disturbed. Disbudding appears to be associated with pain responses that can be obviated by local anaesthesia. Some biotechnological manipulations currently include procedures such as bovine somatotrophin, superovulation, embryo transfer and genetic engineering.