Evaluation of a local goat population for fertility traits aiming at the improvement of its economic sustainability through genetic selection

Ahlem Atoui,Sghaier Najari,María J Carabaño

doi:10.5424/sjar/2018162-12604

Ahlem Atoui, Sghaier Najari + Show 1 more

Open Access

https://doi.org/10.5424/sjar/2018162-12604

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Abstract

The study aims to determine the environmental and genetic components for the reproductive performance of a Tunisian local goat population to set up the basis for the future improvement of this important component of efficient production. The reproductive traits considered were kidding interval (KI) and litter size at birth (LSB). Records of 462 kiddings belonging to 185 dams and 11 sires were collected over a period of 22 years in the caprine herd of the Arid Areas Institute of Médenine. Significance of environmental effects was tested with ANOVA techniques. Genetic parameters were estimated using restricted maximum likelihood fitting an animal mixed model. Mean KI and LSB were 13.85 ± 5.20 months and 1.33 ± 0.49 kids, respectively. The effect of parity number and the interaction between year and month of kidding were significant for LSB and KI. Trait LSB increased with parity number up to the fifth parity while KI decreased with parity number indicating that young females show compromised reproductive performance probably because of growth requirements and scarcity of food resources. A detrimental effect for kiddings occurring during winter (matings in summer) was observed from estimates of the year by month of kidding effect. Heritability estimates for KI and LSB were 0.13 and 0.08, respectively. A moderate repeatability estimate of 0.31 was obtained for LSB while 0.17 was obtained for KI. The low estimates of heritability obtained for reproductive traits indicated that accurate selection based on the doe’s own performance will require large amounts of data. However, the estimated genetic variability was substantial, providing the grounds for the genetic improvement of the reproductive parameters in this population.

Highlights

Reproductive efficiency is always considered to be the most important factor ensuring increase in productivity for certain environmental conditions (Hossain et al, 2004)
The effect of parity number and the interaction between year and month of kidding were significant for litter size at birth (LSB) and kidding interval (KI)
Trait LSB increased with parity number up to the fifth parity while KI decreased with parity number indicating that young females show compromised reproductive performance probably because of growth requirements and scarcity of food resources

Summary

Introduction

Reproductive efficiency is always considered to be the most important factor ensuring increase in productivity for certain environmental conditions (Hossain et al, 2004). Increased production effi ciency can be obtained from goats since they have a high reproductive efficiency with the potential for increased litter size and shorter generation interval in comparison to other farm animals (Safari et al, 2007). The goats’ reproductive performance is an indicator of their adaptation to adverse conditions. Reproduction (understood as the ability to produce viable offspring) is a complex composite trait influenced by many components including puberty, estrus, ovulation, fertilization, pregnancy, parturition, lactation, and mothering ability. The level of reproductive performance of goats is dependent on genetic and environmental factors, but this performance is sensitive to the latter (Song & Sol, 2006). Year, season and parity were some of the factors that affected fertility in different studies (Safari et al, 2007)

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