INFLUENCE OF NAKED NECK GENE (Na) AND DIETARY PROTEIN LEVEL ON GROWTH PERFORMANCE AND CARCASS PARTS AND COMPOSITION OF MALE SHARKASI CHICKENS | ||||
| Assiut Journal of Agricultural Sciences | ||||
| Article 2, Volume 37, Issue 1, March 2006, Page 67-84 PDF (373.12 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ajas.2006.273945 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
| M. N. Makled; A. Abd El - Rahman | ||||
| Animal And Poultry Prod. Dep. Assiut Univ. Assiut | ||||
| Abstract | ||||
| A total number of 770 males from three genotypes, namely heterozygous naked neck (Na/na), homozygous naked neck (Na/Na) and normally feathered (na/na) were compared for growth and meat production performance at two levels of dietary protein (15 and 17% till 8 wks and 13 and 15% till 16 wks). The main results could be summarized as follows: 1- The presence of Na gene led to a significant (P<0.01) increase in body weight. The Na/na genotype was heavier than na/na genotype by about 2.80%, 2.60%, 13.30% and 10.70% at 4, 8, 12 and 16 wks of age, respectively. The corresponding values for Na/Na were 2.70%, 1.03%, 11.80% and 7.70% at the same ages, respectively. Also a highly significant difference (P<0.01) in body weight gain was shown due to genotype. High protein level improved significantly (P<0.01) body weight and gain where body weight increased by 2.4%, 1.4%, 6.4% and 6.6% whereas body weight gain improved by 4.90% from 0-8 wks and 8% from 9-16 wks of age, respectively. The Na/- birds consumed less feed than na/na sibs and the reduction was about 7% and 11.80% in Na/na and Na/Na genotypes, respectively. The presence of Na gene improved significantly feed conversion. Also, the results indicate a significance increase (P<0.01) in feed consumption and conversion values due to low level of protein. 2- The presence of Na gene improved the dressing percentage by about 6.7% and 9.20% in Na/na and Na/Na genotypes. Breast meat increased by 16.70% and 18.20% whereas thighs meat increased by 11.40% and 16.40%. Moreover, high protein level significantly (P<0.01) improved dressing, breast and thighs meat percentages by about 3.40%, 7.10% and 3.70%, respectively. The presence of Na gene significantly (P<0.01) reduced fat percentage in breast and thigh meat. Low protein level significantly reduced protein percentage whereas it increased the fat and ash percentages in both breast and thigh meat. In conclusion, the results of the present study clearly indicate that naked neck birds (Na/-) exhibited superiority in growth and meat production performance. However birds were less sensitive to low dietary protein level as compared with normal feathering genotype (na/na), which may be due to the lower requirements for feather growth | ||||
| Keywords | ||||
| Naked neck gene; protein level; growth; meat composition | ||||
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