Experiments to identify physiological attributes of immature cattle that are correlated with breeding value for milk yield have been reviewed. From the results, the measurement of growth hormone and its secretion when challenged with secretagogues currently appear most promising. Although measurements of kinetic parameters associated with thyroid hormones have given positive results, further study has been inhibited by the need to use radioisotopes and by perceived associations with metabolic rate. Measurements of metabolites and insulin under a range of conditions have, in general, not been of significance or, where initial results were encouraging, have proven not to be repeatable. It was concluded that future experimentation must be on a larger scale than has previously been the case and this would best be achieved through international collaboration.
|Number of pages||6|
|Journal||Livestock Production Science|
|Publication status||Published - 1991|
- dairy cattle genetics physiology juveniles possible selection criteria plasma-hormone concentrations inter-breed relationships growth-hormone dairy-cattle metabolic challenges butterfat production energy equilibrium multibreed designs endocrine control