[Practical application of recombinant bovine somatotropin: sequelae for man, animal and animal husbandry]

Recombinant Bovine Somtatotropin (r-BST) may be produced commercially in the forseeable future. On the basis of a study of the literature, it may be assumed in all likelihood that administration of r-BST to dairy cows will not have a negative effect on public health. However additional research on potential biological activity of recombinant-BST or its fragments and of somatomedins after oral administration, is advisable. Negative effects on the health, fertility and life-span of animals were not observed so far under experimental conditions but any reference to field situations is absent in the literature. Treatment with r-BST should not be initiated prior to within eighty days after parturition. Administration of r-BST also requires proper management in terms of ration formulation and feeding to ensure maintenance of health and production of dairy cattle. The use of r-BST will result in a less accurate estimation of the breeding potential of selected cows, resulting in a reduction of the genetic improvement of milk production. Increased economic benefits should be obtained on farms having high stocking rates (2.35 dairy cows/ha) compared with those having low stocking rates (1.90), varying with the price of r-BST. It is anticipated that the use of r-BST will have little effect on the reduction of the number of dairy cattle and dairy farms up to 1995.