Effect of introducing the naked neck gene in a line selected for low residual feed consumption on performance in temperate or subtropical environments.

The aim of this study was to investigate the possibility of combining the naked neck gene with a genetic background that has been optimized for feed efficiency of laying hens at moderate temperature. In 1997, the naked neck gene was introduced into a line selected for low residual feed intake. In 2003, after 6 generations of introgression, 8 males and 56 females heterozygous for the NA*NA mutation were used to generate all 3 genotypes (NA*N/NA*N, NA*NA/NA*N, NA*NA/NA*NA), in 2 hatches, for rearing in Taiwan and France, respectively, at 3-wk intervals. Growth performance, anatomical traits, laying traits, and feed efficiency were recorded in each country. In addition, comb and rectal temperatures were measured in Taiwan. Performance was generally lower and mortality of laying hens was higher in Taiwan (11%) than in France (1%). Genotype x environment interactions were rare: genotype x environment was observed only for body weight at 10 wk of age and was close to significance for egg weight. The laying performance was significantly decreased in Taiwan by about 25%. The naked neck genotype had a negative effect on body weight and a positive effect of clutch length and egg weight. It also affected heat dissipation traits such as wattle length and rectal and surface temperature measurements. There was a clear additive and negative effect of the NA*NA mutation on rectal temperature. Feed intake and residual feed intake were increased in the homozygous carriers of the NA*NA mutation, which may improve heat tolerance of the low residual feed consumption (R-) line. Feed efficiency tended to be better in NA*NA/NA*NA hens in both environments. Thus, the introduction of the NA*NA mutation in the R- background appeared to be favorable from the viewpoint of feed efficiency, but it did not improve laying performance in a subtropical environment. Other factors than temperature, such as diet composition and lighting regimen, may be involved.

[Study on localization of cystic fluid antigen of Cysticercus cellulosae using McAb-IGSS].

A study was undertaken on the localization of specific combination of McAb against cystic fluid antigen of Cysticercus cellulosae by immunogold silver staining method (IGSS). It was shown that the combination sites of McAb F3 were distinct in the frozen and paraffin sections of Cysticercus cellulosae. The black granules in the bladder walls presented double-layer distribution and those in the scolex folded sites concentrated into pieces. The combination sites of McAb labeled by IGSS against cystic fluid antigen of Cysticercus cellulosae were consistent with the distribution of the cell layers of Cysticercus cellulosae. The sections in the control group had scarce and irregular distribution, which could be differentiated distinctly from those in the experimental group.