Phosphorus requirements for 60- to 100-kg pigs selected for high lean deposition under different thermal environments
Autor: | A, Saraiva, J L, Donzele, R F M, Oliveira, M L T, Abreu, F C O, Silva, S E F, Guimarães, S W, Kim |
---|---|
Rok vydání: | 2012 |
Předmět: | |
Zdroj: | Journal of animal science. 90(5) |
ISSN: | 1525-3163 |
Popis: | Two experiments were conducted to determine the requirement of available P (aP) of pigs selected for high lean deposition during summer (maximum and minimum temperatures of 29.8 ± 3.6 and 21.3 ± 1.1°C, respectively; Exp. 1) and winter (maximum and minimum temperatures of 24.7 ± 2.1 and 9.1 ± 1.6°C, respectively; Exp. 2). Pigs (66.5 ± 2.8 kg, Exp. 1; and 61.1 ± 0.6 kg, Exp. 2) were randomly allotted to 5 dietary treatments. Exp. 1 had 5 pens/treatment and Exp. 2 had 6 pens/treatment, and all pens had 2 pigs. Treatments were composed of a corn-soybean meal basal diet and 4 diets with additional dicalcium phosphate to obtain 5 aP concentrations (0.122, 0.187, 0.252, 0.317, and 0.382% in Exp. 1, and 0.135, 0.200, 0.265, 0.330, and 0.395% in Exp. 2). Pigs were allowed ad libitum access to their respective diets for 30 d. In Exp. 1, increasing aP improved ADFI and ADG (quadratic, P0.05), with maximum responses obtained at 0.226 and 0.256% of aP, respectively. Increasing aP improved (P0.05) G:F. A broken-line analysis indicated that G:F was maximized (P0.05) at 0.295% of aP or 9.04 g of aP/d. Increasing aP also increased (quadratic, P0.05) P and Ca (g/kg) in the metacarpals with maximum responses obtained at 0.314 and 0.272% of aP, respectively. The percentage of ash in the metacarpals continued to increase (linear, P0.05) with increasing aP. In Exp. 2, ADG and G:F improved (linear and quadratic, P0.05) as aP increased in the diet. A broken-line analysis indicated that G:F was maximized (P0.05) at 0.316% of aP or 10.58 g of aP per day. However, increasing aP had no effect on ADFI. Percentages of ash, P, and Ca in the metacarpals increased (linear, P0.05) with increasing aP. In conclusion, results of this experiment indicated that finishing pigs (60 to 100 kg) kept in a thermoneutral environment require 0.316% aP in the diet (10.58 g/d) to maximize G:F, but the requirement is only 0.295% aP (9.04 g/d) when pigs are under heat stress. |
Databáze: | OpenAIRE |
Externí odkaz: |
Pro tento záznam nejsou dostupné žádné jednotky.