BROWN PLUMAGE JAPANESE QUAILS ARE THE BEST BIRDS POPULATION FOR THE LARGE-SCALE EGG PRODUCTION

This study was conducted to investigate the effect of the line of Japanese quails on several production traits of 800 hatched eggs in three populations differ in plumage color, Brown-line (n = 300), Black-line (n = 220) and White-line (n = 280). Variables growth traits were examined on weekly intervals, namely live body weight (LBW), egg weight (EW), egg numbers (EN), hen day production (HD%) and feed conversion ratio (FCR) in the entire investigated period. Results indicated the presence of a significant effect of the studied lines on the majority of investigated traits. Concerning LBW, Black-line showed higher values than Brown and White lines respectively, in the last three weeks of measurements. Concerning EW, no obvious superiority was recorded for each investigated line except for the 10th week, in which significant (P<0.01) higher values of Brown-line were observed over the other two lines. Meanwhile, Brown-line had exhibited significantly (P<0.01) higher EN and HD% values over Black and White lines, respectively. On the contrary, FCR in White-line scored higher values starting from the 10th week to the end of the experiment (12th week) than Black and Brown lines, respectively. In conclusion, this study demonstrated the obvious superiority of Brown-line over Black and White lines in the egg production traits measured. Since Black-line showed relatively higher values in LBW, we may suggest it for meat production. Meanwhile, Brown-line is the best-suited population for egg production. The observed data can be used by breeders in the large-scale egg production purposes of Japanese quails.


Introduction
Japanese quails (Coturnix coturnix japonica) is the smallest farmed avian species. This small sized birds belong to the same family of chicken and pheasant (Phasianidae) and characterize with obvious similarity in their physical characteristics and behavior (Gecgel et al., 2015). It is well known that Japanese quails are increasingly been widespread in poultry industry sector for meat and egg production worldwide (Dhaliwal et al., 2004). These hardy birds can live in small cages (44 birds/ m²) and inexpensive to keep (Priti and Satish, 2004). Furthermore, they have high egg production capacity, and attend sexual maturity in about 6 weeks of age. Japanese quails get their full egg production rates at around 50 days of age (Krishna et al., 2015) and their substantial capacity to benefit from food is well established (Al-Daraji et al., 2010, Al-Salhie et al., 2017, Beski, 2019. Furthermore, many Japanese quails' populations characterize with interesting resistance to many aggressive diseases that invade chickens, with subsequent minimization for medication and vaccination strategies (Santos et al., 2011).
The quails † genetic quality is one of the controlling factors in the success of Japanese quails economically, so the selection of good quality quails is extremely mandatory , Dzuriatmono et al., 2019. It is necessary to estimate genetic parameters for Japanese quails to set a breeding program up (Vali et al., 2005). A selection program not only affects the egg production traits but also the feather color, which is associated with several candidate genes that have a likelihood with feather color. It has been found that the variations in feather colors have a strong linkage with quantitative traits (Delmore et al., 2016).
Yet, it is observed that most farmers faced a problem to get a good quality of quail line for meat or egg production (Nasar et al., 2016). As well, information about growth performance and feather color mutations are not enough to estimate their use for commercial *Author for correspondence : E-mail : baquralhilly_79@yahoo.com production. For instance, many kinds of research indicated that white-feathered quails have been found to exert less body weight characters than the brown quails (Minvielle et al., 2005, Petek et al., 2004. Therefore, it is mandatory to compare among Japanese quails having different plumage colors to investigate to assess which one is best in terms of eggs and meat production. Thus, the proposition of the advantageous improvement strategy could be conducted by making a direct comparative study between different lines of quails. Several recent studies have been conducted to compare the productive traits in these lines of quails (Al-Khafajy et al., 2018. However, more accurate large-scale data are required to get more concise results to assess the best Japanese quails and other related birds whether in terms of eggs or meat production . Therefore, this study aims to observe and determine the meat and egg production performance of three lines of Japanese quails having three distinct colors, Black-line, Brown-line and White-line. The necessity of this study can be attributed to characterize the production performance between the three lines and to help improve the breeding strategy in each specified line.

Experimental design
Initially, a total of (800) newly hatched quail chicks (Brown-line n = 300, Black-line n = 220, White-line n = 280) were randomly picked up from the available stock. All three lines were purchased from the directorate of Agricultural research / Ministry of Agriculture, Baghdad, Iraq, in which all these three lines were raised from many generations. Birds were kept under the same management conditions throughout the study at the poultry research farm of the College of Agriculture, Al-Qasim Green University. In the first two weeks' chicks exposed to continuous lighting and gradually reduced to 16 hr light and 8 hours of darkness. The temperature in quails † house was 38ºC in the first two weeks, then gradually reduced to around 20ºC in the 6 th week (Al-Khafajy et al., 2018). The included Japanese quails' populations were divided into two main periods; rearing period and production period. The rearing period was started from one day of birth until five weeks old. Quails at this period were fed with a starter diet consisting of 3020 Kcal/kg of feed metabolizable energy and 24% crude protein. In the meantime, chicks were kept on deep litter in individual barriers. Subsequently, the second period, production period, was started from the 6 th week to the 12 th week. In this period, males were excluded from the experiment and equal numbers of three populations of females (Brown-line, n = 80, Black-line, n = 80 and White-line, n = 80) were included in the study. All females of these three populations were raised in a battery cage system (Hussein et al., 2019). The birds were kept under the same living conditions and received the same feed. In this production period, female quails were fed with a first laying diet consisting of 2950 Kcal/Kg of feed metabolizable energy and 20.5% crude protein (Recommended composite feed from the directorate of agricultural research/Ministry of Agriculture, Baghdad, Iraq). Birds were fed ad libitum and water was freely available during the study. Farm biosecurity and standard hygienic precautions were maintained strictly to prevent the outbreak of any potential infection bacterial or fungal infection (Sarhan et al., 2019;Al-Shuhaib et al., 2020). Sex determination was performed by observing the cloaca foam in the males at the end of 5 th week (Alkan et al., 2008;Hussein et al., 2002).

Productive data recording
Concerning LBW, records were taken weekly for both sexes at the period of one day to 5 th week of age, with a total of 800 chicks included. Following 5 th week, the recording of live body weight (LBW) at the sexual maturity was restricted only on the separated females, with a total of 240 quails included. Then both egg weights (EW) and egg numbers (EN) for each line were identified by on weekly intervals (6 th week-12 th week). Subsequently, hen day production (HD%) was calculated, since HD% is one of the most important parameters for evaluation of egg production performance in livestock. In analyzed weeks, starting from the first day to the 12 th week of birth, feed consumption ratio (FCR) was calculated since it gives a clear evaluation for broiler quails production performance in the entire analyzed period.

Statistical analysis
The collected data were analyzed by the general linear model procedure of SAS statistical package software (SAS, 2012) to explore the influence of each analyzed line (Brown, Black, and White) on the production traits measured. DuncansC multiple range test was applied in the comparison between means. The following General Linear Model (GLM) procedure was fitted to the following data; Where Y ij is the dependent variable, µ is the overall mean, L i is the effect of lines (Brown, Black, and White) on the production traits recorded, e ij is the random residual effect of each observation. P-values of less than 0.05 were considered statistically significant for all comparisons. Interaction between variables was computed using univariate analysis in the general linear model procedure of SAS statistical package ver. 9.

Results
Regarding the first five weeks of raising period (1 st -5 th week), in which both sexes were recorded, our results showed significantly high values of LBW (P < 0.01) restricted between Brown-line and Black-line over Whiteline. The superiority of the Brown-line at the 1 st , 2 nd and 4 th week was recorded, while Black-line showed higher values in the 3 rd and 5 th week than the other investigated lines. More remarkable superiority of Black-line after separating the two sexes from each other was observed, with exception to the 7 th , 8 th and 9 th week, in which the Brown-line had higher body weight values. However, our results showed significantly higher values of LBW (P < 0.01) for the Black-line and Brown-line females in most of the analyzed weeks than the White-line table 1.
Non-significant differences in EW between the three studied lines in almost all studied weeks were observed table 2. Only one exception for this non-significant observation was detected in Brown-line. This line had exhibited significantly (P < 0.05) higher values of EW in the 10 th week.
The same line (Brown-line) had also shown higher EN values than Black and White lines respectively in the majority of the investigated weeks table 3.
The recorded values in table 4 referred to significantly higher values of HD% (P < 0.01) in the Brown-line than White-line and Black-line respectively. However, Whiteline had given higher values of HD% only in the 6 th and 7 th week.
Significantly higher values for FCR (P < 0.01) in the Brown-line in studied 4 th week to 9 th week were observed. Thereafter, White-line and relatively Black-line, had scored significantly (P < 0.01) higher values of FCR in 10 th week to 12 th week than the Brown-line.

Discussion
This comparative evaluation of three different lines of quails is being conducted to find the best line convenient for egg/meat production which is considered as the ** ** ** ** ** ** ** ** ** ** ** ** Means having different letters in the same column differed significantly. ** (P < 0.01). Measurements were recorded in gm. Means having with the different letters in the same column differed significantly. *(P < 0.05). ** ** ** ** ** ** ** cornerstone for breeders' demands. This study showed obvious LBW superiority toward the Black-line and with a little extent to Brown-line. This trait, alongside the other production-related traits, was measured successively on a weekly basis. In the present study, a variety of fluctuated LBW values were commonly observed among the three investigated lines in this trait. These variations may be due to both genetic and non-genetic factors. However, the present study found that it is profitable to raise quails for the first five weeks of age because the weight gain progress attends its highest ratio in this short period of life. On the other hand, several reports were suggested that the LBW was affected by the gender of the birds (Akbarnejad et al., 2015, Khaldari et al., 2010. This is since females are bigger in body size than males, so it is profitable to be raised after two sexesC separation. However, many researchers have relatively agreed with our recorded LBW values as these data have indicated relatively high carcass weight for both Brown and Black lines than the White line (Minvielle et al., 2005;Petek et al., 2004;Sogut et al., 2015). Interestingly, the recorded LBW values in the Brown-line were decreased at 9 th to 12 th weeks of the experiment. These reduced LBW values may be related to the high efforts performed by this line to produce a higher number of eggs (Pu et al., 2016). For this reason, larger amounts of the consumed food were utilized in egg production and maintenance requirements instead (Yamane et al., 2007).
The present study detected a remarkable role for plumage color in egg production. This observation comes in line with a mass of results that found significant differences in egg production among different lines of quails (Ashok and Reddy, 2010;Hussein et al., 2020). Interestingly, there are several different results about egg production in Japanese quails, some of these in concert with our present study and others are not. However, no easy explanation for these differences is plausible, but the variation in the environmental conditions and sampling error caused by a limited sample size could not be excluded from such explanation (Prado-Gonzalez et al., 2003).
The most important parameters of feed consumption are based on FCR, which is usually measured as the ratio of feed intake to weight gain (Varkoohi et al., 2010). However, there is considerable interest in breeders worldwide to improve FCR values, being a major objective in most breeding programs (Yi et al., 2018). The best FCR values were recorded at almost the first five weeks of age for the White-line, followed by Black-line and Brown-line, respectively. However, after sexual maturity, Brown-line scored better FCR, as well as HD%, values than both Black and White lines. These values indicated that the most economic line in the egg production period is the Brown-line, due to its low FCR.
In conclusion, it can be stated from the obtained data of the current investigation obvious superiority of the Brown-line for egg production and relative superiority of the Black-line for meat production. However, the present ** ** ** ** ** ** ** Means having different letters in the same column differed significantly. **(P < 0.01). ** NS ** ** ** ** ** ** ** ** ** ** study did not suggest breeders consider the White-line for large-scale production purposes, whether in eggs or meat production. This study could be used to assist breeders to choose the best-suited line of Japanese quails for their intended particular production program.