Insulin regulation of amino-acid metabolism in the mammary gland of sheep in early lactation and fed fresh forage

Insulin plays an important role in regulating the partitioning of nutrients to the mammary gland, particularly in lactatingruminants fed concentrate-based diets. There is evidence that the nutritional status of the animals might also affect theirresponse to insulin. This is largely untested in early lactating ruminants fed fresh forage. To investigate nutritional effectson insulin response, 12 lactating sheep, housed indoors, were allocated to one of two treatment groups (hyperinsulinaemiceuglycaemic clamp (HEC) or control) in a randomised block design and fed perennial ryegrass (Lolium perenne)/white clover(Trifolium repens) pasture. Mammary amino acid (AA) net uptake from plasma and utilisation for milk protein synthesis wasmeasured during the 4th day of the HEC using arterio–venous concentration differences, and 1-