[Practical application of recombinant bovine somatotropin: sequelae for man, animal and animal husbandry]. / Praktische toepassing van recombinant bovine somatotropine: gevolgen voor mens, dier en bedrijfsvoering.

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.

[Somatotropin: structure, (bio)synthesis and species specificity]. / Somatotropine: structuur, (bio)synthese en diersoortspecificiteit.

The literature on biosynthesis and species specificity of bovine somatotropin (BST) is reviewed. Somatotropin is a hypophyseal hormone consisting of 190 amino acids, having, among other things, a stimulating effect on milk synthesis. Recombinant DNA-techniques have been used since 1982 to produce BST and this has paved the way for large-scale use of r-BST. It is assumed that the somatotropin molecule has several active sites responsible for a multitude of biological effects following interaction with specific receptors. Somatotropin of different animals have a varying amino acid composition. Sixty-five per cent of human and bovine somatotropins are homologues in amino acid sequence. BST is found to be virtually inactive when used therapeutically in human individuals.