Digestible tryptophan levels in diets for pigs weighing 15 to 30 kg

Lourdes Romão Apolônio,Rita Flávia Miranda De Oliveira,Anderson Lazarini Lima,Aloízio Soares Ferreira,Francisco Carlos De Oliveira Silva,Alysson Saraiva,Juarez Lopes Donzele,João Luís Kill

doi:10.1590/s1516-35982011000800012

Abstract

In order to evaluate the effects of increasing dietary tryptophan levels on performance and carcass characteristics of growing pigs, a total of 60 crossbred castrated male pigs, with average initial and final body weights of 15.50 ± 1.15 and 30.60 ± 1.35 kg were used. Pigs were allotted in a completely randomized block design, with five dietary treatments (0.149, 0.158, 0.168, 0.177, and 0.187% digestible tryptophan, corresponding to digestible tryptophan:lysine relations of 16.0, 17.0, 18.0, 19.0, and 20.0%), six replicates, and two animals per experimental unit, which was represented by the pen. Experimental diets and water were supplied ad libitum throughout the experimental period. The average maximum and minimum temperatures inside the rooms were of 21.5 ± 1.12°C and 26.4 ± 1.91°C, respectively. There was no effect of digestible tryptophan on daily feed intake or protein deposition of pigs. Body weight gain increased quadratically with increasing digestible tryptophan in the diets up to 0.175% maximum response. Increasing digestible tryptophan in the diets linearly improved feed conversion of pigs. The greatest weight gain of 15 to 30 kg castrated male pigs is obtained at 0.175% digestible tryptophan, corresponding to a digestible tryptophan:lysine relation of 18.82% and an estimated daily intake of 2.32 grams of digestible tryptophan.

Highlights

Feed formulation based on the values of amino acid digestibility of ingredients and application of the ideal protein concept – understood as the balance of feed amino acids capable of supplying without excesses or deficiencies the requirements of all amino acids necessary for proper maintenance of the growth – has made it possible for nutritionists to obtain diets with lower protein levels, without impairing the performance of pigs
In order to evaluate the effects of increasing dietary tryptophan levels on performance and carcass characteristics of growing pigs, a total of 60 crossbred castrated male pigs, with average initial and final body weights of 15.50 ± 1.15 and 30.60 ± 1.35 kg were used
The greatest weight gain of 15 to 30 kg castrated male pigs is obtained at 0.175% digestible tryptophan, corresponding to a digestible tryptophan:lysine relation of 18.82% and an estimated daily intake of 2.32 grams of digestible tryptophan

Summary

Introduction

Feed formulation based on the values of amino acid digestibility of ingredients and application of the ideal protein concept – understood as the balance of feed amino acids capable of supplying without excesses or deficiencies the requirements of all amino acids necessary for proper maintenance of the growth – has made it possible for nutritionists to obtain diets with lower protein levels, without impairing the performance of pigs In this concept, lysine, because of its constancy in body protein and its preferential metabolic destination for deposition of lean tissue (Kessler, 1998), has been used as reference for the establishment of the requirements of other essential amino acids, expressed as a relation or percentage of the value of digestible lysine in the diet. The variations in estimates of digestible tryptophan requirement of growing pigs, reported in the literature, may be caused by the differences among genotypes and sanitary standards of the animals, level of dietary protein and digestibility of the tryptophan of the feed ingredients (Guziketal., 2005)

Objectives

Methods

Results