In pursuit of a better broiler: tibial morphology, breaking strength, and ash content in conventional and slower-growing strains of broiler chickens

Midian N Santos; Tina M Widowski; Elijah G Kiarie; Michele T Guerin; A Michelle Edwards; Stephanie Torrey

doi:10.1016/j.psj.2022.101755

In pursuit of a better broiler: tibial morphology, breaking strength, and ash content in conventional and slower-growing strains of broiler chickens

Poult Sci. 2022 Apr;101(4):101755. doi: 10.1016/j.psj.2022.101755. Epub 2022 Jan 30.

Authors

Midian N Santos¹, Tina M Widowski¹, Elijah G Kiarie², Michele T Guerin³, A Michelle Edwards⁴, Stephanie Torrey⁵

Affiliations

¹ Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada; Campbell Centre for the Study of Animal Welfare, University of Guelph, Guelph, ON N1G 2W1, Canada.
² Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
³ Campbell Centre for the Study of Animal Welfare, University of Guelph, Guelph, ON N1G 2W1, Canada; Department of Population Medicine, University of Guelph, Guelph, ON N1G 2W1, Canada.
⁴ Ontario Agricultural College, University of Guelph, Guelph, ON N1G 2W1, Canada.
⁵ Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada; Campbell Centre for the Study of Animal Welfare, University of Guelph, Guelph, ON N1G 2W1, Canada. Electronic address: storrey@uoguelph.ca.

Abstract

This study was conducted to determine the differences in bone traits in 14 strains of broiler chickens differing in growth rate. The strains encompassed 2 conventional (CONV; ADG_0-48 >60 g/d) and 12 slower-growing (SG) strains classified as FAST (ADG_0-62 = 53-55 g/d), MOD (ADG_0-62 = 50-51 g/d), and SLOW (ADG_0-62 <50 g/d), with 4 strains represented in each SG category. A total of 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m²) in a randomized incomplete block design, with each strain represented in 8 to 12 pens over 2-3 trials. From each pen, 4 birds (2 males and 2 females) were individually weighed and euthanized at 2 target weights (TWs) according to their time to reach approximately 2.1 kg (TW1: 34 d for CONV and 48 d for SG strains) and 3.2 kg (TW2: 48 d for CONV and 62 d for SG strains). Tibiae samples were dissected, and length and diameter were recorded. Left tibiae were used for tibial breaking strength (TBS) at both TWs and tibial ash at TW2. At TW1, CONV birds' tibiae were narrowest and shortest (P < 0.001), yet had similar TBS compared to the other categories (P > 0.69). At TW2, category (P > 0.50) had no effect on tibial diameter, yet CONV birds had the shortest tibiae (P < 0.001). The CONV birds had greater TBS:BW ratio than FAST and MOD birds at both TWs 1 and 2 (P < 0.039) and similar ash content as the other categories at TW2 (P > 0.220). At 48 d of age, CONV birds had the greatest absolute TBS (P < 0.003), yet lower TBS:BW ratio than SLOW birds (P < 0.001). Tibiae from CONV birds were longer than MOD and SLOW birds, and thicker in diameter than the other categories, yet CONV birds had the lowest dimensions relative to BW (P < 0.001) at 48 d, indicating a negative association between accelerated growth and tibial dimensions. These results indicate that differences in functional abilities among categories may be due to differences in morphometric traits rather than differences in bone strength and mineralization.

Keywords: bone health; chicken; genetic; growth rate; lameness; slow-growth.

MeSH terms

Animals
Bone and Bones
Chickens*
Diet
Female
Male
Tibia* / anatomy & histology