AbstractsBiology & Animal Science

Four Cheviot wethers, approximately five months of age, were used in an experiment designed to investigate, by phosphorous balance method, the comparative value of forage phosphorous from hay cut at two different stages of maturity, grown on phosphate-fertilized and unfertilized plots. Fertilization resulted in a considerable increase in the percent phosphorous in the fertilized forage over that in the unfertilized but this increased forage phosphorous was not fully available to the animals. The indications were that this was a direct result of the increased physiological age and resultant lower digestibility of the fertilized forage. This was borne out by the fact that the forage phosphorous in the hay cut at the pre-bloom stage, which had a higher digestibility, was more available to the animals than that cut at the more mature stage of growth.