Abstract

LOHMANN, A.C. et al. Dietary digestible valine levels for barrows from 15 to 30 kg. Arch. zootec. [online]. 2012, vol.61, n.234, pp.267-278. ISSN 1885-4494.  https://dx.doi.org/10.4321/S0004-05922012000200011.

The objective of this study was to evaluate the digestible valine levels for barrows from 15 to 30 kg of weight. In the first experiment, to determine the nitrogen balance, were used 20 barrows, averaging 22.88±1.19 kg of initial weight, individually allotted in metabolic cages in a randomized blocks design, consisting of five treatments (0.60, 0.67, 0.74, 0.81, 0.88% of digestible valine) and 4 replications. In the second experiment we determined animal performance in 40 barrows, with initial weight of 15.49±0.06 kg, submitted to the same treatments, experimental design and replicates used in the first experiment. The retained N: absorbed N ratio showed a quadratic effect, indicating 0.748% as an optimum level of digestible valine. Total N excretion showed a quadratic effect depending on the digestible valine levels, being reduced until 0.730% of digestible valine and from this level the N excretion increased again. The efficiency of valine utilization for weight gain decreased linearly as the digestible valine increased in the diets, and according to the Linear Response Plateau model was observed a reduction of this parameter up to 0.790% digestible valine. It was concluded that the level of 0.748% of digestible valine was the most appropriate when considering the retained N: absorbed N ratio, for barrows from 15 to 30 kg of live weight.

Keywords : Branched chain amino acids; Performance; Nitrogen metabolism.

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