Maintenance valine, isoleucine, and tryptophan requirements for poultry

Abstract

Poultry maintenance requirements for valine, isoleucine, and tryptophan were measured by nitrogen balance using different unit systems. The nitrogen balance trial lasted 5 d with 48 h of fasting (with roosters receiving only water+sucrose) and the last 72 h for feeding and excreta collection. Forty grams of each diet first-limiting in valine, isoleucine, or tryptophan was fed by tube each day (3 d) to give a range of intakes from 0 to 101, 0 to 119, and 0 to 34 mg/kg BW d of valine, isoleucine, and tryptophan, respectively. A nitrogen-free diet containing energy, vitamins, and minerals, meeting the rooster requirements, was offered ad libitum during these three d. To confirm that the amino acids studied were limiting, a treatment was added with a control diet formulated by adding 0.24 g/kg of L-valine, 0.21 g/kg of L-isoleucine, and 0.10 g/kg of L-tryptophan to the diets with lower amino acid level. Excreta were collected during the last 3 d of the balance period and the nitrogen content of the excreta was analyzed. For each amino acid, a linear regression between nitrogen retention (NR) and amino acid intake was performed. The equations from linear regression were: NR=-98.6 (±10.1)+2.4 (±0.2)×Val, NR=-46.9 (±7.1)+2.3 (±0.1)×Ile, NR=-39.5 (±7.7)+7.3 (±0.4)×Trp; where Val, Ile, and Trp are the intakes of valine, isoleucine, and tryptophan in mg/kg body weight per d, respectively. The valine, isoleucine, and tryptophan required to maintain the body at zero NR were calculated to be 41, 20, and 5 mg/kg body weight per d, respectively. For the system unit mg per kg of metabolic weight, the intake of valine, isoleucine, and tryptophan was 59, 32, and 9, respectively. Considering the degree of maturity of the animal and body protein content (BPm (0.73)×u), the amounts of valine, isoleucine, and tryptophan required for maintenance were calculated to be 247, 134, and 37 mg per unit of maintenance protein (BPm (0.73)×u) per d. Maintenance requirement is more adequately expressed as body protein content.

Productive and Reproductive Responses of Breeder Japanese Quails to Different Dietary Crude Protein and L-Valine Levels

“…Valine is critical not only for synthesis of the selective novel protein but also for the collapsed protein stability (Zhang et al, 2017). In the same direction, Peganova and Eder (2002) and Lima et al (2016) verified the relationship between increasing of valine requirements in birds and its priority to synthesize egg and feather protein. Japanese quails in this study were adult birds thus there is no need for AAs to maintain the slight increase in adipose tissue.…”

Factorial models to estimate isoleucine requirements for broilers

“…Nevertheless, to predict the efficiency, it is relevant that the maintenance requirement is determined in advance and subtracted from the total amino acid intake. Therefore, the first step described in this study take into account the amount of Ile required for maintenance, as determined by de Lima et al (2016), in order to obtain an accurate amount of Ile consumed that is directed for body deposition. The EU could be a source of variation when dealing with a nutrient modelling.…”

“…It is assumed that maintenance has first priority, and the remaining amino acid will be directed to body deposition. Hence, the amino acid consumed for gain was determined subtracting the amount required for maintenance (de Lima et al, ) from the total amino acid intake.…”

“…The parameter which expresses Ile requirement for maintenance in the Model 1 is based on metabolic body weight (32 mg/kg BW 0.75 days), according to de Lima et al (). The digestible Ile requirement is estimated by the model:where Ile r is the digestible isoleucine requirement (mg/day); BW stands for body weight (kg); EU is the efficiency of isoleucine utilization for body deposition; the DIlec is the linear regression between the deposition of Ile (DIle) and the body weight gain (BWG).…”

“…The Ile requirement for maintenance used in this model was based on protein unit, which consider the body protein weight at maturity (BP m ) and the degree of maturity of body protein ( u ). The parameter that expresses the Ile requirement for maintenance of Bff protein (134 mg/kg ) was according to de Lima et al (). The protein requirement for maintenance of feather is considered equivalent to loss of feathers (Emmans, ).…”