EFFECT OF FORCE MOLTING BY ZINC OXIDE AND THE ROLE OF VITAMIN C ON BODY WEIGHT AND REENTRY TO PRODUCTION OF BROILER BREEDER

A total of 296 Arbor Acres broiler breeder 375 days old were randomly divided into eight treatment. Hens in each treatment were subdivided into five replicates and reared on the floor throughout the experimental period. Two treatments free of Zinc included control with or without vitamin C; six treatments included three levels of Zn as ZnO (15000, 20000 and 25000ppm) with or without vitamin C. All treatments extirpated significant differences in percentage body weight loss during molting program. The most significant loss occurred in the T8 and T7 hens. The most reduction of feed intake (%) occurred in T8, T7 and T6 respectively. Furthermore, molting periods significantly affect body weight loss and feed intake (%). The most significant loss of body weight and reduction of feed intake (%) were occurred at day 9 of molting period. Moreover, T4 hens significantly take up more days to 1st day out of production, less days to out of production and to return to egg production compared with other molting treatments. INRODUCTION The first objective of a forced molt program is to cause hens to cease egg production long enough and enter a non reproductive state that cause body weight loss (Gordon et al., 2009; Khan et al., 2011). The body weight loss has also been identified as a major factor contributing to the forced molting because body weight loss has influence on the successful results of a forced molting procedure (Idowu et al., 2011). Although, a body weight loss of (0.3-0.4 kg) was reported to be necessary for broiler breeders (Baker et al., 1983), El-Deek and Al-Harthi (2004) cited it is not clear what the optimum BW loss of hens should be during a forced molt for broiler breeder. An incomplete molt means a period of unprofitability due to a reduction of egg production and the end of the useful life of a flock (Berry, 2003). Buhr and Cunningham (1994) suggested that the longer the cessation period, the better the post molt production.Maximal improvements appears to have been reached with rests periods of 14-21 day (Hurwitz et al., 1995), to cause hens to totally cease egg production and enter a non reproductive state (Webster, 2003). Hassanabadi and Kermanshahi (2007) stated that the possible reason for the improvement in shell weight is the length of the egg production cessation period. Vermaut et al. (1998) referred to that the only alternatives to the techniques based on feed withdrawal are the feeding of a high-Zn diet or a low-Zn and Cadeficient diet (Breeding et al., 1992). These diets owe their efficacy to the pronounced anorexia, and also to a direct effect on steroidogenesis, that is, an inhibitory action on ovarian granulosa cell function (Johnson and Breke, 1992). Received 7 /6 /2012 accepted 1 / 10 / 2012 Vol. ( 40 ) Suppl. ( 2 ) 2012 ISSN: 2224-9796 (Online) Mesoptamia J. of Agri ISSN: 1815 – 316 X (Print) 10 Heavy breeders seem less responsive to feed changes than do commercial layers, and so it may be necessary to combine programs such as high mineral eg. Zn together with feed restriction (Leeson and Summer, 2009). Zn supplemented diets have been examined as a possible alternative for induction of molt to avoid the problems associated with feed withdrawal forced molt (Moore et al., 2004). Although ample literature is available on production parameters in broiler breeder hens by dietary Zn forced molting (El-Deek and Al-Harthi, 2004; Reddy et al., 2008; Mohammed (2010), a better understanding of the effects of vitamin C to reduced stress due to forced molting, particularly by ZnO addition (15000, 20000 and 25000ppm Zn), is necessary if commercial practices involving forced molting are to be optimized in hens. Therefore, the present study aimed to investigate the effect of different levels of Zn with or without vitamin C addition of molt diet in commercial broiler breeder (Arbor Acres) and their effects on:1. Feed intake, body weight, body weight loss of hens during molting period. 2. The appropriate level of Zn with or without vitamin C addition that could cease the producing of eggs during the fore molting period and return to produce egg without being subjected the hens to great stress. MATERIALS AND METHODS The present study was conduct using 296 hens of Arbor Acres broiler breeder at 375 days old. The experiment was carried out at the Poultry Research Farm belonging to Faculty of Agriculture Science, Sulaimani University in Bakrajo. Each hen received 155g/day,the laying hen diet formulated to meet or exceed recommendations from the Arbor Acres commercial management guide(Arbor Acres Plus, 2007). Birds were randomly divided into eight treatments of 37 hens each. Each treatment contains five replicates (R) with seven hens except R1 and R2 were have eight hens, The eight treatment groups were as fallow: T1: Control group fed on commercial Arbor Acres diet. T2: Control group fed on commercial Arbor Acres diet with (1g/kg) vitamin C for 9 days. T3: Force molting by (15000ppm Zn as ZnO) for 9 days. T4: Force molting by (15000ppm Zn as ZnO) with (1g/kg) vitamin C for 9 days. T5: Force molting by (20000ppm Zn as ZnO) for 9 days. T6: Force molting by (20000ppm Zn as ZnO) with (1g/kg) vitamin C for 9 days. T7: Force molting by (25000ppm Zn as ZnO) for 9 days. T8: Force molting by (25000ppm Zn as ZnO) with (1g/kg) vitamin C for 9 days.On the first day of the treatment, the light program was changed to 8Light:16Dark and water was provided ad libitum. (Table 1). At day10 post molt, hens from all molting treatment were returned to a regular broilerbreeder diet and 16 h/d of photoperiod. Performance data were obtained at day 7 and 9 during the molting period.The basal diet was formulated using a linear program, to contain 2858 Kcal ME/Kg diet and 16% CP to meet, at least the nutrient requirements according to Arbor Acres broiler breeder nutrition manual (Table 2). Individual live weights of birds were measured at just before molting, day 7 and day 9 to determine average of body weight loss. Body weight changes were calculated as the difference between the initial and final body weight of the period. Vol. ( 40 ) Suppl. ( 2 ) 2012 ISSN: 2224-9796 (Online) Mesoptamia J. of Agri ISSN: 1815 – 316 X (Print) 11 Feed intake was measured during molting periods daily by a weighting the residual feed. Table (1): Experimental design of periods and treatments schedule for Zinc induced molting. Table (2): Composition calculated and analytical content of diets.