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This study compared growth and carcass traits of 2 medium-growth crossbred, 4 slow-growth crossbred, 1 commercial slow-growth and 1 commercial fast-growth broiler strains raised in indoor and free-range production systems. One hundred twenty chicks of each strain were raised in each production system. Chicks were raised in indoor pens at a density of 10 chicks per m2. From day 29 until slaughter at 84 days of age, chicks in the free-range system were given outdoor access through doors that were open between 8.00 - 17.00 hours. The study found live weight, feed efficiency, and mortality were significantly affected by strain. However, no significant differences were found between the production systems. Outdoor access varied significantly among strains, with the commercial high-growth and medium-growth crossbred strains making less use of outdoor areas. In terms of performance traits, none of the strains showed any significant differences in performance between the indoor and free-range production systems. However, significant differences among the strains in carcass traits, pH, and colour values of thigh and breast meat were observed in connection with differences in growth rate. Moreover, carcass and breast yields were greater in fast and medium-growth broilers, while ratios of edible inner organs were greater in medium and slow-growth broilers. Keywords: abdominal fat, animal welfare, breast to thigh ratio, feed efficiency, outdoor access, slaughter and carcass traits

Broiler pure lines are valuable breeding species and morphometric traits are advantageous for the selection of breast yield since they could be applied practically and without any negative impact on welfare. In this study, live weight (LW), carcass weight and ratio (CW and CR), breast weight and ratio (BW and BR), abdominal fat weight and ratio (AFW and AFR), morphometric traits such as breast width, length and index (BWD, BL and BI) were investigated in broiler pure lines. The research material consisted of 3 dam (A1, A2 and A3) and 2 sire (B1, B2) pure lines of 42 days of age. LW, CW, BW, AFW, AFR, BR, BL, BWD and BI values were different between the two lines (p<0.05). LW, CW, BW and BI were higher in sire lines. The relationship between breast weight and index were also higher in sire and dam lines than the relationships between breast width and length separately (in sire lines: BWD: 0.73; BL: 0.79; BI: 0.79, in dam lines: BWD: 0.79; BL: 0.74; BI: 0.84). In addition, high r 2 values were determined in regression equations for BW estimation in dam and sire lines (0.836 and 0.857, respectively). Because of the significant correlations between breast yield and its morphometric traits, it is seen that more feasible, ease of measurement, protection of breeding resources and welfare. It is thought that the use of breast index which shows a higher correlation compared to these traits will increase selection efficiency instead of using breast width and length separately.

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Bu çalışma ülkemize ait yerli Gerze tavuklarının yumurta ağırlığı ve yumurta şekil indeksinde yaşa bağlı meydana gelen değişimleri ortaya koymaktadır. Bu amaçla on sekiz haftalık yaşta 120 yerli Gerze tavuğu kümese yerleştirilerek aydınlatma başlatılmıştır. İlk yumurtlamanın gerçekleştiği 22 hafta ile üretim dönemi sonu olarak değerlendirilen 52 haftalık yaş döneminde üretilen tüm yumurtalarda ağırlık ve şekil indeksleri bireysel olarak belirlenmiştir. Bu dönemde toplam 6913 yumurta üretilmiştir. İlk hafta elde edilen yumurtaların ortalama ağırlığı 34.48 gram olarak tespit edilirken 52 haftalık yaşta elde edilen yumurtaların ağırlığı 52.58 grama yükselmiştir. Üretim dönemi boyunca ortalama yumurta ağırlığı 48.32 gram olarak gerçekleşmiştir. Ortalama yumurta eni 39.74 mm olarak hesaplanırken, yumurta boyu 53.76 mm olarak hesaplanmıştır. Gerze tavuklarında ortalama şekil indeksi 74.05 olarak belirlenmiştir.