Comparative studies of muscle histochemical characteristics of ducks between free range and housed, and among three breeds.

摘要

The development and histochemistry of pectoralis and iliotibialis lateralis muscles were studied in 12 Mallard X Khaki Cambell, 12 Indian Runner and 11 Chinese native ducks reared in paddy fields or housed. Birds were either introduced into the paddy fields the week after rice was planted, kept in the fields for 72 days, and then transported to pens and given a layer diet, or were maintained in pens and fed with the same formula diet from the beginning of the experiment. All the birds were killed at 21 weeks of age. Body weight and the weights of pectoralis and iliotibialis muscles did not differ between free range and housed ducks. Body weight was greatest in Chinese native, followed by Indian Runner and crossbred ducks (all P<0.05). Relative tobody weight, the pectoralis muscle was heaviest in crossbred ducks (P<0.05) and the iliotibialis lateralis muscle was heaviest in Indian Runners (P<0.05). Both the muscles were composed of only type II fibres with a high contraction speed. Type II fibreswere subdivided into those with high oxidative enzyme activity (type II A) and those with low oxidative activity (type II B). The pectoralis muscle was composed of around 70% type II A fibres and 30% type II B fibres. The iliotibialis lateralis muscle was composed of around 40% type II A fibres and 60% type II B fibres. The housed Chinese native ducks had more type II A fibres and less type II B fibres in the iliotibialis lateralis muscle than the free range birds. Among the breeds, crossbreds had thehighest percentage of type II A fibres and the lowest of type II B fibres in the pectoralis muscle (P<0.05) and Indian Runners had the highest percentage of type II A fibres and the lowest of type II B fibres in the iliotibialis lateralis muscle (P<0.05). Type II A fibres had a smaller diameter than type II B fibres in both the muscles. Crossbreds and Indian Runners had a larger diameter of type II B fibres in the pectoralis muscle. In the iliotibialis lateralis muscle, Indian Runner and Chinese nativehad a larger diameter of both type II A and II B fibres.