Genetic association between sexual maturity and weekly live-weights in laying-type Japanese quail

Abstract

This study focused on the estimation of genetic relationships between weekly live weights and sexual maturity of male and female Japanese quail. The live body weight data of a laying-type quail line over time were collected from hatching to six weeks of age. Sexual maturity was determined as the day of production of cloacal gland foam for males, and the day of laying the first egg for females. (Co)Variance components and genetic parameters were estimated, using MTDFREML, a restricted maximum likelihood (REML) procedure using a model with direct and maternal genetic effects. Heritability estimates of weekly live weights ranged from moderate to high (0.20 -0.60), and were higher for males than for females. The variance due to maternal effects disappeared gradually for males but rapidly for females as the chicks grew older. Heritability of age of sexual maturation was 0.24 ± 0.008 and 033 ± 0.136 for males and females, respectively. Genetic correlations between ages of reaching sexual maturity and live weights (except hatchling weight) were favourable for males (-0.16 to -0.45) and unfavourable for females (0.14 to 0.22). Genetic correlations between males and females ranged from moderate (0.46 ± 0.083) to high (0.98 ± 0.139) for weekly live weights, and were 0.71 ± 0.24 for age of reaching sexual maturity. Sexual size dimorphism can be explained by the differences in pattern of heritability and correlation estimates between reaching sexual maturity and live weights for males and females.

Relationship between Body Weight and Linear Body Measurements in Japanese Quail (<i>Coturnix coturnix japonica</i>)

“…Sexual dimorphism has previously been reported in favour of the male in duck [23], pigeon [24], and pheasants [25,26]. The growth pattern of male and female Japanese quails raised in other environments have been well documented [20,[27][28][29]. The growth pattern observed in the present study agrees with the pattern reported in refs.…”

“…[16,17] who reported that the age is a major determinant of growth and physiological development. The body weight and linear measurements obtained in this study were however lower than values reported by other authors [18][19][20][21].This is not unexpected in morphometric traits assessments of birds belonging to different populations [22]. The coefficient of variation for morphometric traits suggest that there was an increased uniformity in body size measurements as the birds advance in age, especially among the female quails.…”

“…For example, it was reported in ref. [20] that there were no sex differences in hatchling weight and that the degree of sexual dimorphism was low until after 4 weeks of age.…”

“…The growth pattern observed in the present study agrees with the pattern reported in refs. [20] and [29]. For example, it was reported in ref.…”

Relationship Between Age and Body Weight at Sexual Maturity and Some Egg Production Traits In Three Varieties of Japanese Quails.

“…According to Sezer et al (2006), the initial growth pattern and body weight at sexual maturity are the main factors which affect the performance of birds in the laying phase.…”