Influence du gène Na (« Cou-nu ») sur la croissance, la consommation alimentaire et la composition corporelle du poulet selon la température ambiante

Performance of Naked Neck versus Normally Feathered Coloured Broilers for Growth, Carcass Traits and Blood Biochemical Parameters in Tropical Climate

“…In general, the lower mean body weight (Table 2 and Figure 2) of Na/Na and Na/na than na/na genotypes from first to third weeks of age were in accordance with the findings of Decuypere et al (1993). The higher mean body weights of Na/Na and Na/na broilers than na/na from four to seven weeks of age were in agreement with the findings of Bordas et al (1978), Hanzl and Somes (1983) and Zein-El-Dein et al (1984b).…”

“…The higher but non-significant difference in feed efficiency (lower FCR) for naked neck as compared to normal broilers at 86°F ambient temperature has also been reported by Bordas et al (1978), Monnet et al (1979), Hanzl and Somes (1983), Horst (1988a,b), Eberhart and Washburn (1993) and Singh et al (1996) while significantly better FCR for Na/na over na/na has been reported by Yalcin et al (1997b) and Khan (1998).…”

Carcass measurements of naked neck and normal chicks

“…Among differences associated with genotype at Na locus, that concerning weight of plumage in per cent of body weight is in line with results obtained by B ORDAS et al (1978) and MotvrrET et al (1979). Conversely, the data of B ORDAS et al (1978) do not show differences between males of different genotypes at the Na locus for relative weight of the heart, nor for per cent of bone and muscle, but these percentages concerned only the thigh, while in the present work they relate to the whole carcass.…”

“…The naked neck gene (Na) has been found associated with lower chick mortality in response to high sublethal temperature (SMITH & L EE , 1977) and with better growth rate at room temperature kept above 30 °C till the age of 10 weeks (B ORDAS et al, 1978 ;M ONNET et al, 1979). In a comparison done in Egypt at two hatching seasons, it was found (Z EIN -E L -D EIN et al, 1981) that heterozygous chicks for the naked neck gene were at an advantage for growth in the hotter season. Concerning effects associated with this gene on body composition, an important reduction of plumage weight, in absolute terms and in p. 100 of live weight, has been shown (BO RDAS et al, 1978 ;M ONNET et al, 1979).…”

Potential usefulness of the Na (Naked Neck) gene in poultry production

“…This table does not include traits associated with fatness. For abdominal fat as defined according to Ricard and Rouvier (1967) and Bordas et al (1978), on male chickens raised at 31"C, did not find significant differences associated with genotypes at the Nu locus; a tendency to a slightly higher value for Nuked Neck birds might reflect their higher growth rate at this temperature. On the other hand, Zein-el-Dein ef al.…”