The White Leghorn chickens are the most productive white egg layer and are used in commercial egg production all over the world. Leghorn breed is single comb and completely covered in dense white feathers and will lay about 250-300 white eggs annually. Leghornhavebeen a preferred for commercial egg production due to smaller size and over the top egg production. The White Leghorn hen is not considered as broody hen, so most of these eggs would have to be incubated. Females may only reach 1.5-2 kg and roosters about 2.5-3kg. The dynamic potential of these chickens have not been fully subjected and modern procedures has not been tested to improve the performance on varieties of leghorn chickens. Molting is a skill or techniques, practiced commercially to cease egg production in breeding and laying hens, to recycle them for another season of production. After the molting, egg production and quality may improve significantly as compared to pre-molt period. Forced molt stimulated egg production rate and diminished itsage dependent rate decline, reduced the proportion of egg quality (Hurwitz et al., 1998). With to lie for additional laying periods, thus spreading fixed costs over longer time and more units of production. Induced molting has been reported to improve egg production and other performance parameters (Usman et al., 2013; Akram,1998; Lee, 1982,) Increasing age of birds has been associated with decreased production (Bogdanova et al. 2006; Cloete et al. 2006). Higher feed intake was observed in older hens than in young birds (Mehta et al. 1986). However, Yasmeen et al. (2008) did not find effect of age on feed intake, whereas, the feed efficiency was decreased. Contrarily, Vargas et al. (2009) indicated that Feed Conversion Ratio was not influenced by age in breeders. Egg quality was increased with the advancing age of pullets (El-Aggoury et al. 1989). Hence, a study was articulated to estimate the efficiency of Pre-molt hens at 5570 weeks of age before forced molting on production performance of strains of white leghorn. However, no physical indication is available regarding Comparative study on Pre molting productive performance of leghorn layers. Keeping in view the significance of leghorn chicken in our Circumstances, the present study was planned to comparative study on the pre molting performance of different strains of white leghorn layers and then best productive birds will chose for further study on the influence of various methods of induced molting on performance and health of leghorn layer.
MATERIALS AND METHODS
Four hundred (400) white leghorn hens of two varieties/strain group i.e. Hisex as A (55 to 70 weeks) and Novagin as B group (55 to 70 weeks) were selected. There were two hundred (200) hens from each variety/ strain of birds in each group. These were randomly maintained in floor system for 16 weeks to evaluate their premolt productive performance, including feed intake, body weight, egg production (Hen Housed egg production and Hen Day Production) and Giblet weight. The hens were then prepared for another study of induced molting with the help of feed withdrawal, low energy feed, low energy feed with Alum and wheat middling (Akram, 1998) and all parameters of productive performance will be record during that study of Post-molt performance. The experimental birds were fed a balanced ration, formulated according to NRC (1994) standards and recommendations made by summers and Leeson (2005).
RESULTS AND DISCUSSION
Feed Intake (Kg): In the present study, non-significant feed consumption (13.328 kg /16 weeks) was observed in Hisex layers, while Novagin feed consumed 13.100kg/16 week of trail. This could be indorsed to higher pre-molt body weight and better egg production which might have increased feed requirement of birds resulting in higher feed intake. In pre-molt birds, higher body weight and better egg production have been showed which consequently consume more feed during Post-molt relative to premolted layers have also been reported (Hurwitz et al., 1998). The maximum feed intake was observed in Hisex (13.328 kg) strain/ variety. The increased feed consumption has been associated with production traits (Hurwitz et al., 1998) and Hisex variety had higher egg production which might explain the increased feed consumption in this assortment in line with current findings Bell and Weaver (2005) observed that feed consumption varied in different varieties/ strains. The similar findings have also been reported in another study showing great erraticism in feed consumption in different strains (Reddy et al. 2008). However, Hurwitz et al. (1998) did not find difference in feed intake among different strains. In this study, Hisex chickens (55 to 70 weeks) had non- significant feed consumption (13280 kg). Higher body weight with increasing age and environment might be the reason of increased feed intake in Hisex chickens (Hurwitz et al. 1998). The feed consumption of mature aged chickens was reported to be higher than in young birds (Mehta et al., 1986).
Live Body weight (gm): Results of the current study showed significantly higher body weight (1950± 25 gm / 16 weeks) of pre-molted layers of Hisex, while the body weight of Novagin strain was 1866 ± 25gm/ 16 weeks. Higher body weight in Pre-molted birds has been reported may be due increase age. The increase trend in body weight due to progress of age seemed to be a natural phenomenon. However, Ocak et al. (2004) did not find any difference between pre-molt and post molt body weight. The highest body weight was recorded in Hisex birds followed by Novagin strain (P<0.05). Higher body weight has been observed previously in aged birds (Akram 1998; Aslam et al. 2012). In current study, significant difference in body weight among different varieties of white leghorn breed has been observed (Table 2). Carcass Weight and Dressing percentage.
It was observed that the average carcass weight of broilers reared under the group A and B was recorded as 1150 and 1134 gm/bird, respectively. However, the carcass weight of broilers of group A was found to be statistically higher (P>0.05) than B groups. It was noted that the dressing percentage of broilers of group A (62.1%) was higher than group B (59.9%), all groups of white leghorn layers were found to be statistically similar (P>0.05) for dressing percentage. The results for Carcass weight and dressing percentage were present in the (Table-2).
Weight of Giblets (gm)
Mean values regarding various relative organ weight of the white leghorn breeds of different Strains/ Varity groups have been shown in Table 2. Statistical analysis of the data regarding relative weight (gm/b) of liver, spleen, heart and gizzard did not show any significant difference in the mean values among the strains groups due to pre-molting programme when compared to each other group. Maximum average weight of liver was recorded in group B (43.5gm/b), while A group was 42.5 gm/b. The average weight of gizzard recorded in group A (34gm/b), while B group was 33.2gm/b. The average weight of heart recorded in groups B (11.01gm/b), while A group was 10.69. The weight of Spleen showed relatively higher in group A (811.01gm/b), while B group was 6.5 11.01gm/b.
Hen housed egg production: Hen housed egg production (Table 2) was statistically better in all the pre- molted groups of leghorn breed. The cumulative hen housed egg production had also revealed a dissimilar trend with A and B group recorded the highest hen housed egg production of 62.5percent eggs in Hisex strain of white leghorn breed, while in Novagin with the lowest (59.5 percent eggs). The statistical analysis revealed significant difference (P<0.05) on hen housed egg production of pre- Molted layers due to continuation of laying.
Hen day egg production: The overall pre- moltor non-molted results of the study showed that chickens in group A (89 percent) recorded the highest hen day egg production followed by birds in group B (83 percent) (Table 1). First Pre-molt period or non-molted period, the analysis of variance of data revealed significant difference among groups. Comparison of means indicated that the chickens in non-molted/ Pre- molted layer of Hisex groups had higher hen day production compared to their respective Novagin strain/ Varity, which could be attributed to loss in body fat deposits in the ovary (Table 2). Current finding are in line with those of previous studies indicating decrease in egg production with increasing age (Buhr and Cunningham, 1994).
Based on the findings of this study, it may be stated that overall productive efficiency was improved in Hisex strains/ variety of chickens during the premolt research trail with better productive performance than Novagin variety. The higher Egg Production and better live body and dressing percentage were recorded in pre- molting leghorn layer of Hisex strains.
The authors were grateful for the Executive Director and thankfully acknowledge administration of Sindh Poultry Vaccine Center, Karachi, Department of Livestock and Fisheries, Government of Sindh, for facilitating and funding the present experiment.
This article was originally published in Lasbela University, Journal of Science and Technology, vol. V, pp.65-68, 2016.
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