In pursuit of a better broiler: carcass traits and muscle myopathies in conventional and slower-growing strains of broiler chickens.

Abstract

Selection for accelerated growth rate and high breast yield in broiler chickens have been associated with an increase in myopathies, including wooden breast (WB) and white striping (WS). To investigate effects of growth rate on carcass traits and incidence of myopathies, 14 strains were evaluated, encompassing 2 conventional (CONV; strains B and C: ADG0-48>60 g/d) and 12 slower-growing (SL) strains. The latter were categorized based on growth rate: FAST (strains F, G, I and M; ADG0-62=53-55 g/d), MOD (strains E, H, O and S; ADG0-62=50-51 g/d), and SLOW (strains D, J, K and N; ADG0-62<50 g/d). In a randomized incomplete block design, 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m2), with each strain represented in 8-12 pens over 2-3 production cycles. From each pen, 4 males and 4 females were processed at 2 Target Weights (TW) based on their expected time to reach 2.1 kg BW (TW 1: 34 d for CONV; 48 d for SL strains) and 3.2 kg BW (TW 2: 48 d for CONV; 62 d for SL strains). Weights and yields for the carcass, breast, drumsticks, thighs and wings were obtained; breast fillets were assessed to determine the presence and severity of WB and WS. At both TWs, breast yield was higher as growth rate increased (P<0.001), with CONV having greater breast yield than other categories. Strain F had the greatest breast yield at both TWs (P<0.001) within the FAST category. At TW 2, CONV had the greatest incidence of WB and WS (P<0.001). However, within FAST, strain F had the greatest incidence of myopathies (P<0.001) at both TWs, exhibiting values as high or greater than CONV birds. The incidence of WB and WS in strains with differing growth rates but high breast meat yield suggests that the latter may play a major role in the occurrence of these myopathies.

Providing organic macro minerals and an elevated platform improved tibia characteristics, and increased locomotion and performance of fast- and slower-growing broilers

“…(2021) . In addition, slower-growing broilers had lower prevalence of wooden breast compared to fast-growing broilers, which is supported by previous studies ( Dixon, 2020 ; Santos et al., 2021 ). Overall, slower-growing broilers showed lower performance, mortality and prevalence of wooden breast compared to fast-growing broilers.…”

Characteristics of broiler chicken breast myopathies (spaghetti meat, woody breast, white striping) in Ontario, Canada

“…Although the presence of WB and WS have been reported in some slow and fast growing Canadian broilers ( Santos et al, 2021 ), no systematic studies have addressed the morphological characteristics and severity of breast myopathies (SM, WB, and WS) in commercial Canadian broilers. Therefore, the objectives of the study were to describe the physical and histological characteristics of SM, WB, and WS from commercial broiler chicken flocks in Ontario, Canada, and to assess associations between the severity of myopathies and physical and histological characteristics of the affected breast muscle fillets.…”

In pursuit of a better broiler: walking ability and incidence of contact dermatitis in conventional and slower growing strains of broiler chickens

“…These categories were also the lightest birds at TW 1, suggesting that differences in BW contributed more to performance in the LTL than did genetic potential for growth rate. The lower BW of ONV birds despite their greater growth performance was mainly due to the processing age that occurred earlier than the expected time for CONV strains to reach 2.1 kg ( Santos et al, 2021a ). On the other hand, the lower BW of SLOW birds is attributed to their reduced growth rate (ADG <50 g/d) compared to the other categories ( Torrey et al, 2021 ).…”

“…The results obtained in the group obstacle test partially complement the observations obtained in the LTL test, supporting the hypothesis that selection for accelerated and early muscle accretion may have negative effects on mobility in broiler chickens. The lower number of crossings observed in FG birds may be due to their body conformation (including large breast muscles: Santos et al, 2021a ; and short legs: Santos et al, 2021b ) requiring an altered gait to increase their stability while walking ( Paxton et al, 2014 ) Corr et al (2003b) . suggested that the gait of FG birds is inefficient, rapidly tiring the birds and leading to low activity levels.…”