Table 1.

Summary of the effects of Na gene at different ages and temperatures on weight gain, feed intake, and FCR.

Age	Genotype	Temperature Ranges (°C)	Gene Effect 1 on Parameters			References
			Weight Gain	Feed Intake	FCR
4–6 wk	NaNa vs. nana	32 °C	+22.8%	+12.1%	−9.7%	[58] *
4–8 wk	NaNa vs. nana	32 °C	+38.0%	+25.0%	−11.0%	[58] *
4–6 wk	Nana vs. nana	32 °C	+7.1%	+10.3%	+2.8%	[58] *
6–8 wk	Nana vs. nana	32 °C	+13.1%	+13.9%	+1%	[58] *
5–7 wk	Nana vs. nana	24–32 °C	+8.1%	+1.5%	−5.8%	[59] *
5–7 wk	NaNa vs. nana	24–32 °C	+4.5%	+2.9%	−0.7%	[59] *
0–7 wk	Nana vs. nana	18.7 °C	−0.7%	+4.5%	+5.0%	[60] **
0–7 wk	Nana vs. nana	27.8 °C	+3.1%	−4.0%	−8.5%	[60] **
0–7 wk	Nana vs. nana	31.5 °C	+4.6%	−1.9%	−7.3%	[60] **
4–6 wk	NaNa/Nana vs. nana	12–30 °C	−4.58%		=	[61] *
4–6 wk	NaNa/Nana vs. nana	32–45 °C	+14.6%		=	[61] *
0–20 wk	Nana vs. nana	26.9 °C	+12.88%	+0.4%	−5.2%	[62] **
0–20 wk	NaNa vs. nana	26.9 °C	+7.36%	+1%	−3.15%	[62] **

¹ Gene effect of naked neck genotypes = $\frac{\left(\mathrm{N}\mathrm{a}\mathrm{n}\mathrm{a} \mathrm{o}\mathrm{r} \mathrm{N}\mathrm{a}\mathrm{N}\mathrm{a}\right)-\left(\mathrm{n}\mathrm{a}\mathrm{n}\mathrm{a}\right)}{\mathrm{n}\mathrm{a}\mathrm{n}\mathrm{a}}\times 100$ FCR = feed conversion ratio; * Trial in experimental conditions; ** Trial in commercial conditions.