SPACE ALLOWANCE AND TYPE OF HOUSING FOR GROWING CATTLE - A REVIEW OF PERFORMANCE AND POSSIBLE RELATION TO NEUROENDOCRINE FUNCTION

This paper reviews the effect of space allowance, feeding space and floor type in loose housing and the effect of tie stalls versus loose housing on voluntary feed intake, daily gain, feed conversion ratio, carcass and meat quality, and health. Possible physiological mechanisms involved in mediating housing-induced differences in performance are discussed. Furthermore, animal well-being, practical implications and need for future research are commented. From the review the following conclusions are made: (1) Reduced space allowance from 4.7 to 1.5 m2 per animal changes feed intake, daily gain and feed conversion ratio to 92, 81 and 115%, respectively, for bulls and steers weighing 250-500 kg. (2) Only minor differences in performance are expected in animals kept on deep bedding and slatted floors when animals are compared at the same space allowance. (3) Reducing space at feed manger to less than one per animal in loose housing systems may reduce performance, but more data are needed to quantify the effects (4) Compared to tethered animals, loose-housed animals (greater-than-or-equal-to 4.7 m2 per animal) eat approximately 4% more and have an approximately 4% higher feed conversion ratio, probably due to increased exercise. (5) Loose-housed animals tend to have a higher conformation score and area of longissimus dorsi, less fat, darker meat and a tendency for tougher meat compared to tethered animals. (6) Loose-housed animals have a higher risk of inflamed legs and hoof problems compared to tethered animals. Loose-housed animals also have a higher risk of liver abscesses when they are fed high amounts of concentrates. A low space allowance on slatted floors increases the risk of tail tip lesions. Differences in performance due to space allowance are probably caused by stress. Stress results in changed levels of a multiplicity of hormones orchestrated by the neuropeptides corticotropin releasing factor (CRF), somatostatin (SS) and the catecholamines. A stress-induced reduction of feed intake may be mediated by increased levels of SS, CRF and possibly insulin, glucagon and gastrin. Evidence for the involvement of GH, ACTH, cortisol and testosterone, however, is weak. The mechanisms mediating stress-induced increase on feed conversion ratios are complex and not well understood in ruminants. However, stress may change the function of the gastrointestinal tract, nutrients absorbed, partitioning of nutrients and metabolism. A number of hormones are involved in these mechanisms, including somatotropic hormones. It is concluded that a low space allowance threatens the well-being of bulls and steers.