The effects of growth rate on leg morphology and tibia breaking strength, mineral density, mineral content, and bone ash in broilers.
Fast-growing broilers are especially susceptible to bone abnormalities, causing major problems for broiler producers. The cortical bones of fast-growing broilers are highly porous, which may lead to leg deformities. Leg problems were investigated in 6-wk-old Arkansas randombred broilers. Body weight was measured at hatch and at 6 wk. There were 8 different settings of approximately 450 eggs each. Two subpopulations, slow-growing (SG; bottom quarter, n=511) and fast-growing (FG; top quarter, n=545), were created from a randombred population based on their growth rate from hatch until 6 wk of age. At 6 wk of age, the broilers were processed and chilled at 4°C overnight before deboning. Shank (78.27±8.06 g), drum stick (190.92±16.91 g), and thigh weights (233.88±22.66 g) of FG broilers were higher than those of SG broilers (54.39±6.86, 135.39±15.45, and 168.50±21.13 g, respectivly; P<0.001). Tibia weights (15.36±2.28 g) of FG broilers were also greater than those of SG broilers (11.23±1.81 g; P<0.001). Shank length (81.50±4.71 g) and tibia length (104.34±4.45 mm) of FG broilers were longer than those of SG broilers (71.88±4.66 and 95.98±4.85 mm, respectively; P<0.001). Shank diameter (11.59±1.60 mm) and tibia diameter (8.20±0.62 mm) of FG broilers were wider than those of SG broilers (9.45±1.74, 6.82±0.58 mm, respectively; P<0.001). Tibia breaking strength (28.42±6.37 kg) of FG broilers was higher than those of SG broiler tibia (21.81±5.89 kg; P<0.001). Tibia density and bone mineral content (0.13±0.01 g/cm2 and 1.29±0.23 g, respectively) of FG broilers were higher than those of SG broiler tibia (0.11±0.01 g/cm2 and 0.79±0.1 g; P<0.001). Tibia percentage of ash content (39.76±2.81) of FG broilers was lower than that of SG broilers (39.99±2.67; P=0.173). Fast-growing broiler bones were longer, wider, heavier, stronger, more dense, and contained more ash than SG ones. After all parameters were calculated per unit of final BW at 6 wk, tibia density and bone ash percentage of FG broilers were lower than those of SG broilers.
Department of Poultry Science, University of Georgia, Athens, GA 30602-2772, USA.
M Y
MY
Shim
A B
AB
Karnuah
A D
AD
Mitchell
N B
NB
Anthony
G M
GM
Pesti
S E
SE
Aggrey
D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology*; D002645:Chickens / Q000254:growth & development*; D005260:Female; D006614:Hindlimb / Q000033:anatomy & histology*; D008297:Male; D008903:Minerals / Q000378:metabolism*; D013977:Tibia / Q000502:physiology*
D008903:Minerals; C028705:bone ash