Nutritional plans of digestible phosphorus for growing-finishing barrows

This study was conducted to evaluate nutritional plans of digestible phosphorus for barrows weighing between 30 and 100 kg. Eighty animals were distributed in a randomized block design with five nutritional plans containing 2.19-1.86-1.71, 2.57-2.23-2.09, 2.94-2.61-2.46, 3.32-2.99-2.84, and 3.70-3.36-3.32 g of digestible phosphorus kg−1 of diet, respectively, for the phases of 30 to 50 kg, 50 to 70 kg, and 70 to 100 kg, with eight replications and two barrows per experimental unit. The nutritional plans of digestible phosphorus had no effect on the final body weight, feed intake, daily weight gain, or feed conversion of barrows. The daily intake of digestible phosphorus increased with the dietary concentrations of digestible phosphorus. Of the carcass characteristics assessed, only muscle depth responded significantly to the highest concentration of digestible phosphorus, as assessed in barrows sequentially fed the 3.70-3.36-3.32 g kg−1 diet. The nutritional plans had no effect on backfat, rib eye area, or carcass lean tissue mass, percentage, and deposition. The nutritional plan containing 2.19-1.86-1.71 g kg−1 of digestible phosphorus meet the nutrient requirements for performance and carcass characteristics of barrows weighing from 30 to 100 kg.(AU)

Sex effects on net protein and energy requirements for growth of Saanen goats.

Requirements for growth in the different sexes remain poorly quantified in goats. The objective of this study was to develop equations for estimating net protein (NPG) and net energy (NEG) for growth in Saanen goats of different sexes from 5 to 45 kg of body weight (BW). A data set from 7 comparative slaughter studies (238 individual records) of Saanen goats was used. Allometric equations were developed to determine body protein and energy contents in the empty BW (EBW) as dependent variables and EBW as the allometric predictor. Parameter estimates were obtained using a linearized (log-transformation) expression of the allometric equations using the MIXED procedure in SAS software (SAS Institute Inc., Cary, NC). The model included the random effect of the study and the fixed effects of sex (intact male, castrated male, and female; n = 94, 73, and 71, respectively), EBW, and their interactions. Net requirements for growth were estimated as the first partial derivative of the allometric equations with respect to EBW. Additionally, net requirements for growth were evaluated based on the degree of maturity. Monte Carlo techniques were used to estimate the uncertainty of the calculated net requirement values. Sex affected allometric relationships for protein and energy in Saanen goats. The allometric equation for protein content in the EBW of intact and castrated males was log10 protein (g) = 2.221 (±0.0224) + 1.015 (±0.0165) × log10 EBW (kg). For females, the relationship was log10 protein (g) = 2.277 (±0.0288) + 0.958 (±0.0218) × log10 EBW (kg). Therefore, NPG for males was greater than for females. The allometric equation for the energy content in the EBW of intact males was log10 energy (kcal) = 2.988 (±0.0323) + 1.240 (±0.0238) × log10 EBW (kg); of castrated males, log10 energy (kcal) = 2.873 (±0.0377) + 1.359 (±0.0283) × log10 EBW (kg); and of females, log10 energy (kcal) = 2.820 (±0.0377) + 1.442 (±0.0281) × log10 EBW (kg). The NEG of castrated males was greater than that of intact males and lower than that of females. Using degree of maturity for estimating NPG and NEG, we could remove the differences between sexes. These results indicate that NPG and NEG differ among sexes in growing Saanen goats, and this difference should be accounted for by feeding systems. Including the degree of maturity as predictor cancels out those differences across sexes in protein and energy requirements.