Genetic Effect and Growth Curve Parameter Estimation under Heat Stress in Slow-Growing Thai Native Chickens

Wuttigrai Boonkum,Vibuntita Chankitisakul,Wootichai Kenchaiwong,Srinuan Kananit,Monchai Duangjinda

doi:10.3390/vetsci8120297

Wuttigrai Boonkum, Vibuntita Chankitisakul + Show 3 more

Open Access

https://doi.org/10.3390/vetsci8120297

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Journal: Veterinary Sciences	Publication Date: Nov 29, 2021
Citations: 16	License type: CC BY 4.0

Affiliation: Khon Kaen University, Mahasarakham University

Abstract

Heat stress is becoming a major problem because it limits growth in poultry production, especially in tropical areas. The development of genetic lines of Thai native chickens (TNC) which can tolerate the tropical climate with the least compromise on growth performance is therefore necessary. This research aims to analyze the appropriate growth curve function and to estimate the effect of heat stress on the genetic absolute growth rate (AGR) in TNC and Thai synthetic chickens (TSC). The data comprised 35,355 records for body weight from hatching to slaughtering weight of 7241 TNC and 10,220 records of 2022 TSC. The best-fitting growth curve was investigated from three nonlinear regression models (von Bertalanffy, Gompertz, and logistic) and used to analyze the individual AGR. In addition, a repeatability test-day model on the temperature-humidity index (THI) function was used to estimate the genetic parameters for heat stress. The Gompertz function produced the lowest mean squared error (MSE) and Akaike information criterion (AIC) and highest the pseudo-coefficient of determination (Pseudo-R2) in both chicken breeds. The growth rates in TSC were higher than TNC; the growth rates of males were greater than females, but the age at inflection point in females was lower than in males in both chicken breeds. The THI threshold started at 76. The heritability of the AGR was 0.23 and 0.18 in TNC and TSC, respectively. The additive variance and permanent environmental variance of the heat stress effect increased sharply after the THI of 76. The growth rate decreased more severely in TSC than TNC. In conclusion, the Gompertz function can be applied with the THI to evaluate genetic performance for heat tolerance and increase growth performance in slow-growing chicken.

Highlights

The local chicken breeds are significant for the rural economies of several countries [1] and are considered a genetic resource for use in the development of high-yielding breeds
We examine for the first time the appropriate models for describing the growth curve and the influence of heat stress on the absolute growth rate (AGR) from growth curve parameters in purebred Thai native chickens (TNC) and Thai synthetic chickens (TSC)
The Gompertz function was found to be suitable to estimate the shape of the growth curve in both TNC and TSC

Summary

Introduction

The local chicken breeds are significant for the rural economies of several countries [1] and are considered a genetic resource for use in the development of high-yielding breeds. The local breeds have been used as the foundation stock for breeding through a crossbreeding system with commercial breeds by exploiting heterosis. The excellent characteristics of native chickens are their strengths, resistance to harsh environmental conditions, and poor rearing, without much loss in production. Many local breeds risk extinction (28.83% of local breeds are at risk) because of genetic erosion from government policy and programs, and climate change in terms of heat stress [3,4,5]. Conservation and sustainable development of animal genetic resources (AnGR) requires a broad focus on the many ‘adaptive’ breeds that survive well in the low external input agriculture typical of developing countries

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