| Three studies were conducted to estimate the true ileal and fecal phosphorus (P) digestibilities and the bioavailability of P in field peas fed to growing pigs.Based on the results of the first experiment, a second study was conducted to reevaluate the true ileal and fecal P digestibilities and EPL associated with peas using linear regression analysis. In this study, eight ileal cannulated barrows (average initial body weight 31.89 +/- 2.86 kg) were randomly assigned to four semi-purified test diets containing graded levels of P from peas (0.7, 1.4, 2.1, 2.8 g/kg diet, as fed-basis) according to a replicated 4 x 4 Latin square design. Apparent ileal and fecal digestibility values increased as dietary P concentration increased (P < 0.05). EPL associated with peas was estimated to be 0.18 +/- 0.08 and 0.115 +/- 0.07 g/kg DMI at the ileal and fecal levels, respectively. Overall true ileal and fecal P digestibilities were 53% and 51%, respectively.In the third experiment, 35 individually housed barrows (average initial body weight 6.85 +/- 1.40 kg) were blocked on the basis of body weight and randomly assigned to one of seven semi-purified diets to give five pigs per treatment. The test diets consisted of a cornstarch-soybean meal basal diet (0.6% Ca, 0.25% total P), and the basal diet supplemented with 0.05, 0.10, or 0.15% P from monosodium phosphate (MSP) or pea. ADG, plasma P and bone measurements were regressed on supplemental P intake, and P bioavailability from peas was determined by the slope ratio technique. Estimates for the bioavailability of P ranged from 6% to 29% based upon the response criterion assessed. The P bioavailability values determined with bone mineralization characteristics in the present study were comparable with values determined in previous research.Results from the present studies suggest that the regression analysis technique may be used to determine EPL and true P digestibilities of peas fed to growing pigs. However, these results are highly variable. As well, the bioavailability of P in peas determined using a slope ratio assay are variable and dependent upon the response criterion assessed.In the first experiment, four semi-purified test diets containing graded levels of P from peas (0.7, 1.4, 2.1, 2.8 g/kg diet, as fed-basis) were fed to ileal cannulated barrows (average initial body weight 22.4 +/- 1.7 kg) according to a 4 x 4 Latin square design. True ileal and fecal P digestibilities and endogenous P losses (EPL) were determined using simple linear regression analysis. Apparent ileal and fecal digestibility values increased as dietary P concentration increased (P < 0.05). EPL associated with peas was estimated to be 1.5 +/- 0.41 and 1.2 +/- 0.21 g/kg DMI at the ileal and fecal levels, respectively. Overall true ileal and fecal P digestibilities were 107% and 105%, respectively. |
