Effects of protein concentration on responses to dietary lysine by chicks

Abstract

Chicks were fed on diets varying in crude protein (CP) content (140 to 280 g/kg diet) in either 8 steps, experiment 1, or 6 steps, experiment 2. Protein composition was held constant in each experiment. At each protein concentration, 5 (experiment 1) or 6 (experiment 2) concentrations of lysine were tested, ranging from 40 to 60 g/kg CP. Growth rate and efficiency of food utilisation to 21 d of age responded to increasing dietary protein contents up to about 230 g CP/kg. An estimate of lysine requirement at each protein concentration was obtained by fitting a quadratic curve to the response data and calculating the dose of lysine (g/kg CP) needed to maximise either growth rate or gain/food ratio. Although no growth response to dietary protein was obtained between 240 and 280 g CP/kg, the amount of lysine needed to maximise growth and gain/food ratio over this range increased systematically when expressed as g/kg diet, but remained constant if expressed as g/kg CP. The regression of lysine required (g/kg diet) for maximum performance (growth or food efficiency) on CP (g/kg diet) was strictly linear for both responses in both experiments throughout the entire range studied (140 g CP/kg to 280 g CP/kg). The estimated lysine requirement was 0.053 of the CP in experiment 1 and 0.055 of the CP in experiment 2. It is concluded that a fixed ratio of lysine to protein should be specified in practical diet formulation, rather than a minimum dietary concentration of lysine. This would ensure that, if the dietary protein content rises above a prescribed minimum value in least-cost formulation, an appropriate adjustment will automatically be made to the lysine content of the solution.

Dietas de diferentes densidades energéticas mantendo constante a relação energia metabolizável: nutrientes para codornas japonesas em postura

“…Esses dados sugerem que, semelhantemente ao ocorrido em outras espécies, a exigência quantitativa de lisina para codornas também aumenta com o nível de proteína bruta da ração (Morris et al, 1987;Rose & Uddin, 1988). No entanto, outro fator que pode ter elevado a exigência deste aminoácido é a mudança na relação entre a EM e o nível de lisina na dieta, ou seja, houve melhoria no consumo de lisina.…”

Effect of dietary protein level, amino acid balance and feeding level on growth, gastrointestinal tract, and mucosal structure of the small intestine in broiler chickens

“…The lys:CP ratios in the UPS group with a range of 0.015 to 0.031 g lys·kg -1 CP were lower than the minimum (i.e. 0.057) recommended for maximum growth by Morris et al [26]. The digestibility of crude protein (dcp), which is the amount of total crude protein available to the bird as a result of the chemical nature of the raw ingredients of the particular feed were determined from the European Table of Energy Values for Poultry Feedstuffs [10].…”

Desempenho e rendimento de carcaça de frangos de corte no período de 22 a 42 dias de idade alimentados com dietas contendo diferentes relações lisina digestível: proteína bruta

“…Esses níveis se assemelham aos encontrados por Morris et al (1987), que indicaram proporção de 5,4%, e González et al (1997), de 5,5% de lisina total:proteína bruta, ao utilizarem níveis adequados de PB. Surisdiarto & Farrell (1991) encontraram nível ótimo de lisina para cada nível de PB estudado considerando o ganho de peso e a conversão alimentar, enquanto Sterling et al (2003) recomendaram a exigência de aminoácido como uma proporção constante da PB.…”