Estimation of genetic parameters for egg production traits in Japanese quail (Coturnix cot. japonica) Schätzung genetischer Parameter für Legeleistungsmerkmale bei Japanischen Wachteln (Coturnix cot. japonica)

Keeping Japanese quail is an economic way for producing egg, because of their early sexual maturity (laying egg after 35 days), high egg production (250–270 eggs per year), resistance to most of poultry disease and great egg production persistency on a high level (approximately 14–18 months) (MURAKAMI and ARIKI, 1998). Japanese quail maturation happens in about 6 weeks of age and mature females are usually in full egg production by 50 days of age. With proper care, hens should lay more than 200 eggs in their first year of lay. The average egg weighs about 10–15 g which is about 8% of female body weight. Feed conversion for egg production in Japanese quail is better than in laying hens. Quail hens need less than 2 kg of feed to produce 1 kg of egg, while laying hens need between 1.9 to 2.5 kg of feed to make the same amount of egg. Japanese quail eggs are nearly identical in taste and nutritional quality to chicken eggs. There is an expanding market for products such as fresh or pickled quail eggs in Asian, American and some European countries (MINVIELLE, 2004). Egg production performance is usually assessed in poultry through age (ASM) and weight at sexual maturity (WSM), mean egg weight (MEW) and egg number (EN) during certain production periods (KIANIMANESH, 2000). ASM and WSM are considered as criterions for sexual maturity in birds and refer to age and weight at first egg, respectively. ASM and WSM together with EN and MEW are the most important economic traits in laying birds. Genetic improvement for egg production would increase the production efficiency and profitability of Japanese quail. The possibility of genetic improvement by selection depends on genetic variability of laying performance traits. For genetic evaluation, it is necessary to estimate heritability and genetic correlations between egg production traits. There are some detailed studies on estimation of variance components for egg production traits in Japanese quail (NESTOR et al., 1983; MINVIELLE et al., 1997; MINVIELLE and OGAZ, 2002; SAATCI et al. 2006, KHALDARI et al., 2010; HIDALGO et al., 2011). Considering the importance of such studies in quails, present research was conducted to estimate heritability, genetic and phenotypic correlations of ASM, WSM, MEW and EN from 9 to 12 weeks of age and