An investigation on effects of genotypes, rearing systems and seasons on performance and welfare of broilers grown at Antalya conditions

ABSTRACTAN INVESTIGATION ON EFFECTS OF GENOTYPES, REARING SYSTEMS AND SEASONS ON PERFORMANCE AND WELFARE OF BROILERS GROWN AT ANTALYA CONDITIONSDENİZ İLASLAN ÇÜREKPh.D. Thesis in Animal ScienceSupervisor: Assoc. Prof. Dr. Tülin AKSOYJuly 2010, 165 pagesThe purpose of this study was to investigate the effects of genotypes, rearing systems and seasons on welfare of broilers raised at Antalya conditions. Three different systems were applied: extensive indoor (EI), free range (FR) and label rouge (LR). Two genotypes, fast growing (Cobb 308) and slow growing (Hubbard Isa), were used in the EI and FR raising systems while only a slow growing genotype (Hubbard Isa) was used in the LR system. In all experimental groups, one day old and mixed sex (male and female), fast growing (FG) and slow growing (SG) genotypes were used. Chicks raised under the EI system were confined throughout their life while FR broilers had free outdoor access (1 chick/m2 alfa alfa pasture) after completing four weeks on deep-litter. On the other hand, LR broilers had similar outdoor access with twice (0,5 chick/m2) as much area as the FR group after spending the six-week raising period in deep-litter pens.Broilers grown under EI and FR systems were slaughtered at 56 and 63 th days of age, but LR birds were slaughtered at 82 days of age. Experimental data on performance traits and welfare related characteristics were collected and evaluated. Included were performance traits such as live-weigh gain, feed consumption, feed effiency, as well as welfare related characteristics including walking ability, tibia discondroplasia, duration of tonic immobility, external quality and some blood parameters.The results indicated that the effects of genotypes on performance traits were significant. FG genotypes had a faster live-weight gain, a higher feed intake, more efficient feed conversion ratio and higher incidence of mortality in all rearing systems. The research results also showed better walking ability, lower tibia discondroplasia incidence and better external quality was found in the SG broilers than in the FG broilers. In addition, various blood parameters were evaluated for all groups. The results demonstrated that the heterophil/lenfosit ratio (H/L) and plasma corticosterol levels were higher in FG broilers. Lastly, rectal temperatures were also found higher in FG birds. In Winter and Spring seasons FG broilers had better performance traits than SG broilers. However in summer season FG genotype performance impact hot climate more than SG genotype. On the other hand we determined that SG broilers generally had better welfare traits than FG broilers.KEY WORDS: Fast and Slow growing broilers, season, extensive indoor, free range, Label rouge, performance, welfare