Objective: Study the effects of strain and feed restriction on circulatory and respiratory systems in male meat type pure lines (A, B, C, D) and commercial hybrids of Arian, and their relation to as cites syndrome.
Design: Factorial experiment in randomized complete block design with Iwo factors of feeding regimen and genetic groups with 3 and 5 levels respectively using 6 replications.
Animals: Total of 432 day old chicks from every genetic group. Procedure: Day old chicks of each genetic groups were randomly assigned to the 90 experimental deep floor pens. Each experimental unit consists of 24 chicks. The three levels of feeding regimens were Adlib. (Control) ,95% of adlib. and 90% of ad lib. At the end of every weeks of experiment ( Six weeks duration), a bird of every experimental unit was randomly selected, and before euthanizing were weighted. Samples of heart, lungs, right ventricle and left ventricle was prepared and their weights were determined. Statistical analysis: All measured variables were statistically analyzed using SAS software by GLM procedure. Comparison of means were carried out by Scheffe’s test.
Results: The genetic groups had significant differences in weight of right ventricle/ total weight of ventricles (RV/TV), at periods of (0-21) and (22-42) days of age and in total of experiment length (p<0.05). There were no significant differences between genetic groups in heart weight/body weight and lungs weight/body weight ratios. The three regimens of feeding had significantly affects on ratio lungs weight/body weight in period of (22-42) days of age (p<0.05), with the highest ratio in ad lib. groups. There were no significant interaction between feeding regimens and genetic groups on the studied variables.
Conclusion: The line C, had better balance between the growth of who] e body and the growth of internal organs (heart and lungs) in comparison with the other genetic groups, in other words, the line C is the most resistant strain against as cites syndrome. In contrast line B is the most susceptible to as cites due to imbalance between growth of whole body and internal organs. There is need to improve line B via genetic programs, in order to increase its resistance against as cites syndrome. Between feeding regimens, the Ad lip. birds had highest ratio of lungs weight / body weight in (22-42) days of age. These results showed that continuance of feed restriction not only caused imbalance between growth of whole body and inteil1al organs, but also limited growth of these organs. J. Fac. Vet. Med. Univ. Tehran. 58, 2: 139-143, 2003.