-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.

Fibre traits and glycolytic metabolites in musculus longissimus dorsi of European Wild Boar, Pietrain and Meishan as well as their F1 and F2 crossbred generations were evaluated and compared. Pietrain had the highest relative number of white fibres and the largest muscle fibres. Wild Boar showed the smallest muscle fibres. The R‐value and lactate level of Wild Boar and Meishan were low, whereas Pietrain had high R‐values and lactate levels. The glycogen level was highest in Wild Boar and lowest in Meishan. The F1‐ and F2‐crossbreds often had trait values between those of their founder breeds. Several antagonistic relations between fibre characteristics, muscle metabolites and performance traits for carcass and meat quality have been found. They are family‐specific and strongest within the crossbreds of the Pietrain‐based families.