The genetics of body weight and feed efficiency in broiler chickens

Mebratie, Wossenie

doi:10.18174/472486

Cited by 2 publications

(2 citation statements)

References 136 publications

(227 reference statements)

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“…36 Some evidence suggests that government-run schemes are less successful at enrolling marginalized groups than community run schemes. 37 Most African countries have also established noncontributory (that is fully subsidized) coverage programs. As shown in Figure 5, 80 percent of countries have such programs for the poor, and (separately) a similar proportion of countries have programs for mothers and children under 5.…”

Section: Figure 5 Countries With Health Coverage Programs For Specifmentioning

confidence: 99%

Going Universal in Africa

Cotlear¹,

Rosemberg²

2018

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Section: Figure 5 Countries With Health Coverage Programs For Specifmentioning

confidence: 99%

Going Universal in Africa

Cotlear¹,

Rosemberg²

2018

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“…Intake of feed, which typically represents 60-70% of production costs, are important traits, but difficult or expensive to measure. Since individual recording of feed intake is expensive, only a selective proportion of selection candidates is tested for feed efficiency traits (Mebratie, 2019). For the genetic progress of feed efficiency, the lack of phenotypic data on the traits can be a barrier.…”

Section: Group Recordsmentioning

confidence: 99%

Genotype by environment interactions in poultry breeding programs

Tuan

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Environmental differences between the breeding (B) and commercial production (C) environments may lead to genotype-by-environment interactions (GxE) i.e. re-ranking of breeding values of animals in the two environments. A substantial re-ranking implies genetic progress achieved in breeding programs is not realized in performance of production animals. The issues of GxE are not new and several solutions exist, however, there has not been much focus on solutions for breeding programs for poultry. This PhD-project investigated GxE interactions in breeding programs for poultry and solutions to improve genetic progress in these breeding programs. A strong GxE interaction for body weight (BW) traits was found in broilers that were raised in B and C environments. Indications of GxE were significant re-ranking of breeding values, heterogeneous variances and different heritability for BW under B and C conditions. The genetic correlations between BW traits measured in B and C environments were in the range 0.48-0.54. Genetic variances of C traits were more than 2 times higher than those of B traits. Heritability of C traits (0.31-0.37) were higher than those of B traits (0.27-0.30). In this thesis, several approaches to improve genetic gains of the poultry breeding programs in the presence of GxE have been investigated: phenotyping strategies, optimal modelling of traits, use of group records, and the use of genomic information. Different phenotyping strategies were compared in a breeding program for broilers that used genomic selection. It was found that when the genetic correlations between traits measured in B and C were 0.5 and 0.7, allocation of 70% and 30% hatched birds to B and C environments, respectively, for phenotype testing led to the highest genetic gains among the compared phenotyping strategies. When the genetic correlation was 0.9, moving birds to C did not improve genetic gains of the breeding scheme due to reduced selection intensity. Increasing proportion of birds moved to C (from 15 to 45%) could reduce rate of inbreeding of the breeding program. Optimal modelling of traits was explored in a genetic analysis that was carried out for BW in broilers at different ages raised in a commercial environment. A statistical model was developed with the aim to increase predictive ability of the model for the traits affected by maternal effects. A criterion for the development of the statistical model was based on correlation between EBVs and corrected phenotypes of half-sib individuals. The statistical model also accounted for heterogeneous variances between sexes. In breeding programs for village chicken, where strong GxE interactions are expected, the use of group records was a good option to increase genetic gain of the breeding programs. The use of group records from villages significantly improved genetic gains compared to the scheme without birds tested in the village although group records led to a slightly lower genetic gain compared to individual records. In addition, the use of genomic information was ex...

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The genetics of body weight and feed efficiency in broiler chickens

Cited by 2 publications

References 136 publications

Going Universal in Africa

Going Universal in Africa

Genotype by environment interactions in poultry breeding programs

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