119 Standardized total tract digestible phosphorus requirement of 11- to 25-kg pigs

摘要

A total of 1080 barrows and gilts (PIC; 337 × Camborough, initially 11.4 ± 0.29 kg BW) were used in a 21-d trial to determine the standardized total tract digestible (STTD) P requirement of nursery pigs from 11 to 25 kg. Pigs were allotted to pens at weaning according to BW and gender. There were 6 replicate pens/treatment and 23 to 27 pigs/pen. Pens of pigs were randomly allotted to experimental diets based on average BW 21 or 24-d postweaning, in a randomized complete block design. The 7 dietary treatments consisted of 0.26, 0.30, 0.33, 0.38, 0.43, 0.48, and 0.53% STTD P. The NRC (2012) estimates a 0.33% STTD P requirement for nursery pigs from 11 to 25 kg. Two corn-soybean-meal-based diets were formulated to contain 0.26 and 0.53% STTD P by increasing the inclusion of calcium carbonate and monocalcium phosphate at the expense of corn, maintaining a constant 1.17:1 total Ca:P ratio, with no phytase added to the diets. Diets were blended using a robotic feeding system to achieve the intermediate STTD P levels. Experimental data was analyzed using generalized linear and nonlinear mixed models, fitting the data with heterogeneous residual variances when needed, and pen as the experimental unit. Competing models included linear (LM), quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). Best-fitting models for each response were selected using the Bayesian information criterion. Increasing STTD P improved ADG, ADFI, and G:F (linear, P < 0.05). For ADG, the best-fitting models were LM and QP, estimating the maximum response at greater than 0.53% STTD P for both models. For G:F, best-fitting models were QP and BLL. The QP model estimated the maximum at 0.43% (95% CI: 0.36 to > 0.53%), with 99% of maximum G:F achieved at 0.36%. The BLL plateau was estimated at 0.34% (95% CI: 0.29 to 0.38%). In conclusion, the estimated STTD P requirement for nursery pigs from 11 to 25 kg ranged from 0.34 to at least 0.53% depending on the response criteria and statistical model. 1SEM for ADG, ADFI, and G:F were 11.57, 19.44, and 7.36, respectively. 1SEM for ADG, ADFI, and G:F were 11.57, 19.44, and 7.36, respectively.