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Abstract. This study investigated how early growth was affected in various chicken genotypes, which were fed ad libitum or restricted and with or without poultry red mite (PRM) infestation. Atak-S (AS), New Hampshire Red (NHR), and Light Sussex (LS) genotypes were used in the study. In total, 120 chicks were used from each genotype. Four groups were formed: feed-restricted (FR) and infested with parasite (P+), FR only, fed ad libitum and P+ , and fed ad libitum only. Feed restriction was applied as 20 % of the feed consumption of the group fed ad libitum the day before for each genotype. The study was conducted between 2 to 12 weeks of age. Weekly live weights and feed consumption were recorded, and the feed conversion ratio was calculated. Traps were placed in cages to count parasites. Regarding the live weight, NHR tolerated the PRM infestation in the ad libitum feed conditions better than other genotypes. While the infested NHR and AS birds had lower live weights than the non-infested ones under FR conditions, there was no difference between infested and non-infested birds of NHR and AS genotypes when they fed ad libitum. The feed consumption of infested AS and NHR birds was higher than that of non-infested counterparts when fed ad libitum. By contrast, the LS chicks consumed less food in the infested environment. In conclusion, the genotypes responded differently to PRM infestation in different feeding environments.

In this study, sexual dimorphism in pigeons was investigated. Rensch's rule was evaluated across pigeon breeds. Body weight, body length, beak length, wingspan, tail length, and tarsus length were used for the analysis. We have divided the breeds in the five groups (form, frills and owls, tumbler and rollers, homer and highflyer, feral). The allometric relation in the traits between female and male measures were analyzed. The measure of sexual size dimorphism was measured for each trait as a simple male size divided by female size (Sexual Size Index, SSI). On average across traits, male birds have higher values than female birds, both across breed groups and overall. No deviation from isometric allometry can be observed except the tail length. No trends towards logarithmic female values according to the SSI could be identified. According to the results, the rules of Rensch for pigeon breeds are rejected. Sexual dimorphism exists between breeds and traits, mainly in favor of the male birds. In most cases, allometric relationships between breeds change, as do traits.

Inbreeding, which is the mating of related individuals, increases homozygosity and leads to depression, especially in traits with low heritability. In this study, parent-offspring, full-sibling and half-sibling mating groups were formed and their effects on embryo loss and hatch weight were investigated. In the study, a total of 2130 fertile Japanese quail eggs were used. Embryo losses were divided into three periods; early period (first 5-day), middle period (6-12th days) and late period (13-17th days). It was observed that mating groups affect all traits subject of this study (P≤0.0001). The lowest hatchability of fertile eggs was observed in dam-male offspring mating (DM), while the highest was observed in half-sibling (HS) and control (C) matings (P≤0.05). However, the highest hatch-weight were found in eggs of DM matings (P≤0.05). DM has also the highest embryo losses for all periods (P≤0.05). Most of the embryo losses, except the half-sibling group, occurred in the early period.