Resumo

GONZALEZ, R.M. et al. Protein levels for nursery pig: a meta-analysis. Arch. zootec. [online]. 2014, vol.63, n.242, pp.315-325. ISSN 1885-4494.  https://dx.doi.org/10.4321/S0004-05922014000200010.

To determine the optimum level of crude protein (CP), a meta-analysis with data of seven trials with 240 hybrid nursery pigs individually penned with average body weight 12.57 kg. Growth performance, carcass characteristics, and plasma urea nitrogen concentration were evaluated. ANOVA and regression analysis were performed using a surface response model with RSREG of SAS procedure considering the crude protein (CP) level as well as the effect of trial, year and season; the optimum CP levels were determined to each variable (average daily body gain= 19.25, dorsal fat= 18.1, feed:gain ratio= 17.3 and plasma urea N= 16.5 %), and were corroborated with an additional experiment using 40 hybrid nursery pigs with 11.5 kg of initial weight during 21 d, in a completely randomized design with ten replicates per treatment. The meta-analysis indicated that average daily gain, lean meat gain and plasma urea nitrogen concentration were reduced when CP was lowered (p≤0.05); feed/ gain ratio was improved when CP was reduced (p≤0.05). In the experiment conducted to corroborate the optimum CP levels, there was no difference in the analyzed variables, except the percentage of lean meat, that improved (p≤0.05) when pigs were fed 16.5 and 19.25 % CP. The results indicate that the optimal level of CP is 16.5 % for nursery pigs diets based on sorghum-soybean meal with synthetic AA added, because of at this level of CP, neither production variables nor carcass characteristics were affected and urea concentration in plasma decreased.

Palavras-chave : Crystalline amino acids; Feeding strategies.

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