SUMMARY Development of quality welfare assessment protocols is a necessary step towards achieving high broiler welfare standards. Rapid growth rate and highly intensive commercial production systems have been highly associated with poor welfare indicated by mainly leg deformities, high stress levels and increased fear responses. Stress response in broilers is characterised by increased corticosterone and heterophil-to-lymphocyte ratio especially under heat stress, high light intensity, high stocking density, and an unenriched environment. Rearing environment, genotypes, high light intensity and human handling highly influence fear responses as proved during tonic immobility, open field, novel enrichment, and avoidance distance tests. Lameness which is usually visually assessed by a gait score scale remains an undisputable indicator of poor welfare in broiler production due to its effects on mobility and association with pain. Other leg problems including footpad dermatitis and hock burn also remain significant and they are highly associated with fast growth, high stocking density, poor litter quality, and poor or non-enriched production systems. Litter management and good ventilation are necessary to ensure good plumage conditions, reduction in ammonia emissions thereby promoting the well-being of broilers. Generally, broilers should be motivated and able to exhibit natural behaviours without straining including feeding, drinking, walking, and stretching thereby enhancing bird health, performance, production, and consumer satisfaction. Using a systematic approach, the important welfare parameters including stress, fear response, leg problems, plumage condition, environment, and behaviour are intensively discussed to explore the latest insights of broiler chickens’ welfare.

This study determined the effect of layer age, egg-laying time, cage tier, and cage direction (outward-inward) on egg quality parameters of commercial layer chickens reared in enriched cages. A total of 944 layers (approximately 100 eggs every four weeks, from the 26 to the 58^th week) obtained from Lohmann LSL-Classic layers reared at the Niğde Ömer Halisdemir University Ayhan Şahenk Agricultural Application and Research Centre were analyzed. Laying hen age significantly affected all the egg quality variables (p<0.01). Egg weight, shell-breaking strength, egg surface area, Haugh unit, and yolk color score differed across egg-laying time (p<0.05; p<0.01). There was variability in all the external egg quality traits among the cage tiers (p<0.05), but not for internal egg quality (p>0.05). Furthermore, it was found that cage direction had a significant effect on egg weight, shell thickness, egg surface area, and all the internal egg quality traits, except for yolk color score (p<0.05; p<0.01). In conclusion, our results highlight significant changes in egg quality traits due to layer age, egg-laying time, cage tier, and cage direction.

SUMMARY This paper reviewed the effects of lighted incubation (in ovo lighting) on incubation performance and chick quality in broilers. Globally, the broiler chicken industry is among the fastest growing commercial sectors. Chicken meat has the fastest growth rate compared to other common animal protein sources, and its demand will always increase due to increasing population growth worldwide. Therefore, a need for a proportional increase in hatchery efficacy is also increasing with this demand. Over the past decades, implementation of artificial light during incubation in broiler chickens has accelerated with key considerations such as light colour, light source, photoperiod, eggshell colour, pigmentation, light shape and light intensity. Photostimulation has a significant effect on embryo development during the last quarter (from 14 to 21 day of incubation). However, incubating eggs under light from day 1 to 18 improves embryo development and hatchability compared with lighting for 21 days. A photoperiod of 12 L:12 D improves hatchability, chick weight and leg health compared with 24 L and 24 D. High light intensity decreases hatching traits such as chick weight. While incubation under green light increases muscle growth and weight gain of chicks, lighted incubation with red and white light enhances hatchability compared with other wavelengths and darkness. In conclusion, it is important to continue studies on lighted incubation to identify the exact mechanisms of how other light colours impact embryogenesis and investigate the interaction or synergistic effects of a combination of two or more wavelengths.

This review article discussed the effects of various production systems on the welfare of laying hens. The global egg production capacity has been increasing with the evolving production systems which are driven by the consumer preferences. In developed countries, the egg industry has shifted from focusing on quantity and quality of eggs to asking questions of how these eggs are produced. Animal welfare issues emphasized by consumers in these countries led to the banning of conventional cages as seen by European Union in 2012. Such legal measures have uplifted research in various alternative production systems which are thought to be animal friendly. Countries that have adjusted to alternative systems such as free range are registering an increase in the number of free range eggs which is a positive sign for an industry that is willing to adapt and move forward. However, in developing countries, conventional cages are still being used because they are fundamental to the quantity of egg production which is a success indicator of the egg industry. In addition, lack of awareness within the consumers and local producers that birds are sentient has not helped the poultry industry in such countries. However, the alternative production systems have also not fulfilled all the behavioural needs of the animals and, hen welfare issues such as keel and bone damage are common in enriched and perched systems. Also, the high prevalence of diseases and parasites are observed with significant levels in litter floor and outdoor systems an issue attributable to the direct contact between birds and soil or faces. Due to the continuing welfare issues in all laying hen production systems, it is suggested that in addition to genetic selection for traits like bone strength, reduced feather pecking, research should combine both the modification of equipment‘s or materials used in each production system and environmental factors such as illumination and temperature as an alternative to improve hen welfare.