however, found a significant correlation between the
content of collagen and the shear force value of
chicken skeletal muscles.
Although many workers have attempted to clarify
the relationship between collagen content and
toughness of meat using taste panels and mechanical
tests, no clear relationship has been established.
Nakamura et al. (2004) compared the total amount
of collagen in breast muscles of male Red
Cornish6New Hampshire and normal broilers, and
found collagen content in breast muscles were
3.33 + 0.47 and 1.71 + 0.19 mgyg, respectively. In
the present experiment, the collagen content in
breast muscles were 1.10 + 0.05 and
1.17 + 0.07 mgyg, when birds fed organic zinc 40
and 80 ppm, respectively. They also reported that
tenderness of broiler meat is attributed mainly to
characteristics of the collagen distribution, in which
the majority of Types I and III collagens are distributed
on the closer mesh of endomysial honeycomb.
However, the role of collagen on meat tenderness is
not only dependent on the collagen content but also
on its solubility or cross-linking (Bailey and Light,
1989), as well as the ratio of Type I and Type III
collagen (Burgeson and Nimni, 1992). We
concluded that dietary organic zinc at the level of
40 ppm or more increases both dermis thickness of
tibia and back skin of broilers and collagen content
of back skin, which would improve carcass quality
of broilers.