EFFECTS OF LYSINE OR RUMINALLY PROTECTED LYSINE ADMINISTRATION ON NITROGEN UTILIZATION IN GOATS FED A DIET SUPPLEMENTED WITH RUMINALLY PROTECTED METHIONINE

The objectives of the present study were to investigate whether or not dietary lysine addition could improve N balance of female Japanese Saanen goats at 15 to 32 months of age, weighing 31 to 40 kg, fed on a wheat bran-hay cube diet supplemented with methionine, and whether or not ruminally protected lysine supplementation could give as good an N balance performance as lysine in the presence of ruminally protected methionine when given orally to the goats. It was considered from changes in N balance and N utilization that the first-and second-limiting amino acids in the diet were methionine and lysine respectively, under the present experimental conditions. The ruminally protected lysine in addition to the ruminally protected methionine gave no improvement in N balance and N utilization compared with the ruminally protected methionine alone, suggesting that the ruminally protected lysine used in the present study was not effectively utilized by the goats.