Bone development and activity in chickens in response to reduced weight-load on legs

Abstract

-In order to find out whether a reduction in load-bearing on chicken legs would modify the activity and leg bone tissue, an original suspension device was developed in order to alleviate half of the weight-load on the legs. Thirty-six 5 d-old male meat-type chicks were assigned to 12 groups, each of 3 birds: a control bird (C), a bird equipped with a harness (H) and one equipped with a harness and suspended from a balance (S). The counterweights of the balance reduced the load on the legs by 50%. Behaviour in the birds was recorded twice for a 22-hour period. The birds were slaughtered at 19 d of age. Their legs were then weighed and the humeri, tibiotarsi and femurs were used for computation of length, biomechanical stiffness and composition. Tibiotarsi were also used for histomorphometry. Body weight at 19 d of age was significantly higher in the C birds (642 g vs. 586 g in the H and S groups, P < 0.05). The distance travelled as measured in the second week of the experiment was greater in S birds (338 m per 22 h vs. 246 in the C group and 252 in the H group, P < 0.05). The length of the tibiotarsi and femora was greater in the S birds when corrected for body weight (P < 0.05). Bone stiffness, composition and histological parameters were not significantly different in the 3 groups. We thus concluded that a reduction in load-bearing on the legs of young chicks enhances locomotor activity and longitudinal growth of leg bones. Bone quality was not affected, probably due to the contradictory effects of increased exercise and reduced weight.

Sequential feeding with variations in energy and protein levels improves gait score in meat-type chickens

“…Moreover, it is noteworthy that the improvement in leg condition was of a lesser magnitude than differences in gait score obtained with greater growth reduction (Bizeray et al, 2002;Leterrier et al, 2006). Reduction in BW alleviates mechanical stress on the leg joints and increases the time spent standing (Rutten et al, 2002). The reduction in the prevalence of birds with abnormal gait in the present experiment is probably due to the combined effects of modified growth and motor activity.…”

“…These changes in activity do not appear to be sufficient to improve bone quality, whereas high levels of exercise have clearly demonstrated beneficial effects on broiler bone tissue. Exercise on a treadmill improves vascular patterns of the tibial growth plate (Thorp and Duff, 1988) and strengthens the tibial cortical bone in broilers (Rutten et al, 2002). Floor systems improve the mineral apposition rate compared to cage systems (Vitorovic et al, 1995) and increase the ash content of the humerus (Tolon and Yalcin, 1997).…”

Effects of ambient temperature and early open-field response on the behaviour, feed intake and growth of fast- and slow-growing broiler strains

“…A social reinstatement test measures both the ability of the chickens to walk as well as their motivation to become socially reinstated (Bokkers and Koene, 2004). Although it is not possible to disentangle the two effects in the test used in the present experiment, Ross 208 could be expected to have restricted locomotion caused by their greater BW (Rutten et al, 2002;Bokkers and Koene, 2003).…”

“…Fast-growing broiler strains are considerably less active and perform less appetitive foraging compared with slower growing broilers (Barbato et al, 1980) and layers (Gerken and Jaenecke, 1997). Fast-growing broilers are motivated to perform the same activities as other chickens, but have restricted locomotion caused by their greater BW (Rutten et al, 2002;Bokkers and Koene, 2003). Forcing modern broilers to increase their daily activity has been found to strengthen their legs and reduce the incidence of leg problems (Reiter and Bessei, 1998).…”

Effect of Stocking Density and Dietary Protein Level on Performance, Meat Quality and Serum Corticosterone of Slow-Growing Korean Meat-Type Chicken (Hanhyop 3)

“…육성전기(10∼40일)에는 동일 수준의 단백질 사 료를 급여하고, 육성후기(41∼75일) 사료의 단백질 수준 만 각 19%와 18%로 두 수준으로 설계하였다. 육성전기의 단백 질 수준을 동일하게 한 이유는 한협 3호 육계가 육성후기에 육성전기 대비 두 배 이상의 사료를 섭취하고, 급격한 성장 (Na et al, 1998) (Rutten et al, 2002), 닭의 골격 내 회분함량은 체중과 밀접한 관련이 있는 것으로 보고되었다 (Talaty et al, 2009) 못했던 것으로 판단된다. (Craig et al, 1986) …”