The effects of different feeding management systems on performance of a slow-growing broiler genotype

Tibia properties in broilers raised on their own commercial diets with different growth rates and sex during a 10-week rearing period

BACKGROUND

Genetic selection applied to broilers results in fast growth and an increase in meat yield. However, this situation causes welfare problems in broilers.

OBJECTIVES

The aim of this study is to determine the weekly changes in the tibia characteristics in broilers raised on their own commercial diets.

METHODS

In the study, 168 (84 female and 84 male) slow-growing (Hubbard-Isa Red JA) and 168 (84 female and 84 male) fast-growing (Ross-308) day-old broiler chicks were used. Six broilers from each genotype and sex group were weighed weekly and slaughtered to determine the tibia properties during the 10-week fattening period.

RESULTS

Fast-growing broilers had higher tibia weight and longer length, diaphysis diameter and medullary canal diameter than those of slow-growing broilers at the same age. In fast-growing genotypes, the cortical index was low only in the 2nd week, and Robusticity and Seedor indices were observed to be better throughout the whole fattening. The ash content of the total tibia in the fast-growing broilers was higher in all of the examined weeks except the 4th week and the 9th week of fattening than that in the slow-growing broilers. Although the amount of ash per unit body weight in the 1st week of fattening was higher in fast-growing broilers, this situation reversed after the 4th week. The level of all minerals examined in total tibia weight is high in fast-growing broilers, and they differed according to the fattening period.

CONCLUSIONS

When comparing tibia characteristics of two different genotypes fed their own commercial diets, the tibia structure was found to be stronger in fast-growing broilers compared to other genotypes at the same age, but slow-growing broilers were more prominent in terms of body weight. It was observed that the mineral density was higher in male broilers, except in the 1st week.

Effects of season, genotype, and rearing system on broiler chickens raised in different semi-intensive systems: performance, mortality, and slaughter results

This study aimed to determine the effects of chicken genotype (fast-growing and slow-growing), various semi-intensive production systems (extensive indoor, free-range, and traditional free-range), and season (spring and summer) on animal performance, mortality, growth curve, and slaughter results under semi-environmentally controlled conditions in a subtropical region. Production systems were applied in conformity with the EU standards. While the summer experiment improved performance during brooding (1st-28th days), hot conditions led to a decline in performance during the growing period. In addition, negative effects were determined for all parameters of Gompertz growth curve in summer (P < 0.05, for all). In spring, fast-growing showed 36% higher final live weights than slow-growing, and this difference decreased in summer (16% for extensive indoor and 25% for free-range) (P < 0.05, for all). Fast-growing in extensive indoor and free-range displayed similar weight gains in the growing period, whereas grazing ones consumed less feed (P < 0.05) and thus showed better (P < 0.05) feed conversion. The same situation was true for slow-growing in spring. The mortality was approximately 1% in all groups in spring, while it was 17.36 and 18.06% for fast-growing in extensive indoor and free-range and 1.39, 2.78, and 4.29 for slow-growing in extensive indoor, free-range, and traditional free-range in summer. It is advantageous to choose fast-growing if short-term (56 days) fattening especially under optimum conditions is to be preferred. If the growing period coincides with summer, slow-growing should definitely be preferred and the fattening period should be extended to 82 days. Grazing improved feed conversion (P < 0.05) by reducing cereal-based diet consumption in both genotypes but did not affect carcass yield. However, grazing had a positive effect on fleshing.