Genetic basis of leg health and its relationship with body weight in purebred turkey lines

Abstract

The aims of this study were to estimate the genetic parameters for leg and foot health and mobility in purebred turkey lines and their genetic correlations with BW. Traits were gait score (GS) as an overall measure of leg health, footpad dermatitis (FPD), and 2 skeletal leg health traits, namely, valgus and varus deformities (VVD) and tibial dyschondroplasia (TD). Data from 4 different lines, comprising 3 yr of phenotypic records and 4 yr of pedigree information per line, were used. The sex average BW for the lines at 18 wk ranged from 19.1 kg (line A) to 12.4 kg (line D). The prevalence of VVD ranged from 5.2 to 14.6% and for TD from 4.1 to 23.2%. The average score for FPD on a scale of 0 to 100 ranged from 48.5 to 61.1. Gait Score was scored on a scale of 1 to 5, standardized to a mean of 3 and SD of 1. Heritabilities were estimated at 0.08 to 0.13 for GS, 0.01 to 0.07 for VVD, 0.06 to 0.12 for TD, and 0.10 to 0.15 for FPD (all SE ≤ 0.02). Estimates of the genetic correlations between VVD and TD ranged from 0.03 to 0.21 (all SE ≤ 0.08), and estimates of these with GS ranged from 0.07 to 0.87 (all SE ≤ 0.09). The genetic correlations of FPD with GS ranged from 0.00 to 0.34 (all SE ≤ 0.04), and with the skeletal leg health traits from -0.06 to 0.33 (all SE ≤ 0.06). Body weight showed estimated genetic correlations ranging from 0.28 to 0.51 (all SE ≤ 0.06) with GS, -0.06 to 0.50 (all SE ≤ 0.13) with VVD/TD and 0.05 to 0.34 (all SE ≤ 0.05) with FPD. The results suggest that selection for improved leg health can be incorporated effectively in a commercial turkey breeding program using balanced breeding goals, in which production traits and leg health traits are considered simultaneously.

Higher heritabilities for gait components than for overall gait scores may improve mobility in ducks

“…Gait is a complex trait that requires the integration of sensory input, balance, conformation and fine motor control, and heritability estimates for poultry gait tend to be low [22–24]. Similarly low heritability estimates have been published for visual gait scores in other species [25].…”

Associations between on-farm welfare measures and slaughterhouse data in commercial flocks of turkey hens (Meleagris gallopavo)

“…Therefore, turkeys rejected owing to leg and joint issues, contrary to broiler chickens or ducks, could represent a potential retrospective indicator of lameness on farm. Nevertheless, because lameness in turkeys can be caused by a variety of infections, developmental or degenerative causes ( Kapell et al., 2017 ), the causes of the observed lameness on farm need in-depth pathological examinations to establish more specific causative relationships with the slaughterhouse parameter.…”

Patterns of musculoskeletal growth and dimensional changes associated with selection and developmental plasticity in domestic and wild strain turkeys

“…Despite the apparent maintenance of leg bone strength with increasing mass, the domestic turkey shows poor locomotor performance with increased body mass and many leg health problems (Damaziak et al., ; Emmerson et al., ; Kapell, Hocking, Glover, Kremer, & Avendaño, ; Martrenchar, ). Body mass is known to be more heritable than leg health parameters in turkeys (Kapell et al., ; Swalander, Burnside, & Glover, ), so we find it somewhat surprising that the domestic turkey's bone strength, as indicated by PMA, keeps pace with the wild turkey and predictions from isometry (of course this could also be a plastic, developmental response, as addressed below). If the mineral density and material properties of the bone are consistent in the two strains, we expect the domestic turkey's bones to be just as robust for their mass as wild turkey bones.…”