Genetic analysis of leg problems and growth in a random mating broiler population

Abstract

Improvement in growth has been widely reported as the cause of increased incidence of leg problems in broiler chickens. We report herein the genetic relationship between growth and leg problems in a random mating broiler control population. The traits studied were valgus (VL), varus (VR), and tibial dyschondroplasia (TD), which were expressed on a binary scale of 0 (normal) and 1 (abnormal); growth rates from 0 to 4 wk (BWG 0-4) and from 0 to 6 wk of age (BWG 0-6); and residual feed intake from 5 to 6 wk of age (RFI 5-6). A threshold-linear mixed model was employed for the joint analysis of the categorical and linear traits. Incidences of VL, VR, and TD were 26, 4, and 2%, respectively. Heritability of leg problems ranged from 0.11 to 0.13. Phenotypic correlations alluded to an unfavorable relationship between growth and leg problems; however, the genetic relationship between growth and leg problems was extremely weak, ranging from 0.01 to 0.08. There is, therefore, a basis for genetic improvement in leg problems. However, improved management practices would also be important to reduce incidence of leg problems in broiler chickens.

A Review of Current Knowledge on Staphylococcus agnetis in Poultry

“…Management practices and housing conditions, such as the bedding type, litter condition, lighting program, and stocking density, have been linked to higher incidences of leg disorders [ 29 , 30 , 31 , 32 , 33 , 34 ]. Previous research has highlighted associations between genetics, breed line, gender, growth rate, age, and leg problems in broiler chickens [ 16 , 31 , 35 , 36 ]. For many decades, genetic selection of broiler chickens was focused on improving the feed conversion rate and promoting rapid growth of chickens.…”

Integrative analysis of long non-coding RNA and mRNA in broilers with valgus-varus deformity

“…The heritable nature and bone quality traits of VVD have been reported. Heritability of leg problems ranged from 0.10 to 0.13 and that of bone quality ranged from 0.10 to 0.77 [ 3 , 36 – 38 ]. And the prevalence of VVD has declined through genetic selection [ 1 , 6 , 39 ].…”

“…quality ranged from 0.10 to 0.77 [3,[36][37][38]. And the prevalence of VVD has declined through genetic selection [1,6,39].…”

“…as normal, score = 0; angle between 10˚and 25˚was mild deformity, score = 1; angle between 25˚and 45˚was moderate deformity, score = 2; angle greater than 45˚was severe deformity, score = 3) [2,3]. Affected broilers show abnormalities when standing and walking.…”

“…Valgus-varus deformity (VVD) is a common leg deformity in broilers, which is characterized by varus and valgus at a certain angle of the tibiotarsal bone or tarsometatarsus [ 2 ]. Valgus-varus angulation was classified as normal, mild deformity, intermediate deformity and severe deformity, (tibia-metatarsus angle deviation less than 5° was normal, score = 0; angle between 10° and 25° was mild deformity, score = 1; angle between 25° and 45° was moderate deformity, score = 2; angle greater than 45° was severe deformity, score = 3) [ 2 , 3 ]. Affected broilers show abnormalities when standing and walking.…”