Modelling of the nitrogen deposition and dietary lysine requirements of Redbro broilers

Abstract

The aim of this study was to determine the coefficients of the Goettingen model for Redbro birds and estimate the digestible lysine requirements. To determine the model parameters, three nitrogen balance trials were performed in Periods I (14–28 days), II (42–56 days) and III (70–84 days), using 42 birds per trial. The birds were individually housed and subjected to six diets with increasing levels of nitrogen, with lysine as the limiting amino acid (deficient by 20% in relation to other amino acids). Dietary nitrogen concentrations were 8, 16, 24, 32, 40 and 48 g/kg. A control diet was added to confirm lysine as the first limiting amino acid. Nitrogen balance trials were divided into 5 days of adaptation and two periods of excreta collection, each one of 5 days. The response of the birds to a control diet confirmed that lysine was the first limiting amino acid. The adjustment of the exponential functions between nitrogen retention or excretion and nitrogen intake allowed estimation of parameters of the Goettingen model. The maximum potential for nitrogen retention was 3276, 2585 and 2603 mg/BWkg0.67.day, nitrogen maintenance requirement was 225, 135 and 122 mg/BWkg0.67.day and efficiency of nitrogen utilisation was 313 × 10−6, 406 × 10−6 and 415 × 10−6 in the phases of 14–28, 42–56 and 70–84 days. The digestible lysine intake for Periods I, II and III, based on 60% of the maximum potential for nitrogen retention, was 711, 989 and 1272 mg/day (1.225%, 1.137% and 1.09% of lysine in the diet for a daily feed intake of 58, 87and 117 g/day), respectively.

Nitrogen maintenance requirements and potential for nitrogen retention of pullets in growth phase

“…A validation of the model parameter b as a measure of dietary protein quality, which is independent of the actual level of pro- 2004b, 2004cWecke & Liebert, 2009;Pastor et al, 2013), and it is also can be observed in However, several studies (Daulat et al, 2015;Dorigam et al, 2014;Pastor et al, 2013;Santos et al, 2014;Samadi & Liebert, 2008;Wecke, Pastor, & Liebert, 2016) presented similar characteristics where a decrease in threshold values with increasing age was observed, indicating that the genetic potential is independent of the diet (Samadi & Liebert, 2008).…”

“…It is difficult to compare the data with other experiments due to variations in strains, age, feed intake and dietary characteristics. However, several studies (Daulat et al, ; Dorigam et al, ; Pastor et al, ; Santos et al, ; Samadi & Liebert, ; Wecke, Pastor, & Liebert, ) presented similar characteristics where a decrease in threshold values with increasing age was observed, indicating that the genetic potential is independent of the diet (Samadi & Liebert, ).…”

Optimal in‐feed amino acid ratio for laying hens based on deletion method

“…The values determined to NR max T are difficult to compare with the data of other experiments due to variations in strains, age, feed intake and dietary characteristics. However, several studies with animals in growth (Daulat, et al, ; Dorigam, et al, ; Pastor, et al, ; Samadi & Liebert, ; Santos, et al, ; Wecke et al, ) presented similar characteristics where a decrease of threshold values with increasing age was observed, indicating that animals at maturity tend to have lower values and that the genetic potential is independent of the diet (Samadi & Liebert, ).…”

“…However, this is an important parameter used for the modelling procedure of the amino acid requirements (Samadi & Liebert, ). Studies with the Goettingen approach for laying hens are few (Sünder et al, ), but there are already studies with broiler breeder hens (Dorigam et al, ), pullets (Bonato et al, ; Silva et al, ) and broilers in growth phase (Samadi & Liebert, ; Pastor et al, ; Santos et al, ; Daulat, Wecke, Sharifi, & Liebert, , Wecke, Pastor, & Liebert, ).…”

“…However, this is an important parameter used for the modelling procedure of the amino acid requirements (Samadi & Liebert, 2006a, 2006b. Studies with the Goettingen approach for laying hens are few (Sünder et al, 2010), but there are already studies with broiler breeder hens (Dorigam et al, 2017), pullets (Bonato et al, 2015;Silva et al, 2013) and broilers in growth phase (Samadi & Liebert, 2008;Pastor et al, 2013;Santos et al, 2014;Daulat, Wecke, Sharifi, & Liebert, 2015, Wecke, Pastor, & Liebert, 2016 Silva et al (2013) and Bonato et al (2015) (Daulat, et al, 2015;Dorigam, et al, 2014;Pastor, et al, 2013;Samadi & Liebert, 2008;Santos, et al, 2014;Wecke et al, 2016) presented similar characteristics where a decrease of threshold values with increasing age was observed, indicating that animals at maturity tend to have lower values and that the genetic potential is independent of the diet (Samadi & Liebert, 2008).…”