Broiler breeders hens (meat-type hens) have lower reproductive potential than laying-type hens. Statistical models for predicting potential laying pattern are important for economically optimal breeding strategy of egg production in a poultry flock. The aim of the study was to find the most suitable function for describing the egg-laying rate and egg weight during the broiler breeders’ production period and to characterize laying pattern in groups of hens with different egg production. The following four mathematical models were used: gamma, Narushin-Takma, logistic-curvilinear, and compartmental. The daily recorded egg production data from 100 broiler breeder hens were used. Hen-weekly egg production was described using laying rate during successive weeks after reaching sexual maturity (26 weeks of age) and daily recorded egg weight. On the basis of the total number of eggs laid (NEggs), groups of hens with low (21%), intermediate (52%), and high (27%) egg production were created. The differences between the goodness-of-fit criteria values (AIC, R² MSE) were small, with all the examined models having the same quality of curve fitting for egg-laying rate and egg weight. The logistic-curvilinear model was able to fit well both egg-laying rate and egg weight of the whole broiler breeder hens’ flock, and also when hens were divided into three egg production groups. This model could be considered in a long-term prediction of the reproductive potential in the commercial management. Moreover, the presented model could be useful in the research on different reproduction parameters of individual hens.

The aim of the work was to analyze the genetic structure of the population of Tatra Shepherd dogs, registered in branches of Polish Kennel Club from Tatra Mountain Region. Data were pedigrees of 102 Tatra Shepherd dogs (33 males and 69 females) born between 1994 and 2011. Inbreeding and relationship coefficients, as well as effective number of founders and ancestors, were calculated. These statistics give the picture of genetic diversity of the population. Average inbreeding coefficient was 7.17%, whereas average relationship coefficient was 18.20%. The number of inbred animals and the mean FX values steadily increased over time. Twenty-six of 80 inbred animals had inbreeding coefficients higher than 10%. The effective number of founders was relatively high in relation to the population size (the effective number of ancestors was four times lower) and both were similar to the results of studies of other authors on different dog breeds. The total contribution of only 4 ancestors was enough to explain 50% of the gene pool of the population. Therefore, mating of related animals should be avoided in order to prevent the further increase of inbreeding level, because almost all Polish and foreign Tatra Shepherd dogs living now originate from the population under study.

Analyses were conducted on pedigrees of 845 animals registered at the Hovawart Club in Poland (113 dogs and their ancestors). The degree of inbreeding was calculated for the whole population (0.0026) and separately for male dogs (0.0021) and bitches (0.0031), and the coefficient of mean relationship was calculated for the entire population (0.0064), among male dogs (0.0064), among females (0.0073) and between males and females (0.0061). The inbreeding and relationship coefficients obtained are lower than those estimated for Polish populations of other dog breeds. The calculated effective number of founders (268) and ancestors (233) may indicate rather low genetic diversity. Preferences of breeders concerning coat colour were discussed. Black and tan coat dogs dominated at first, followed by blond ones, and over the last five of the analysed years black coat dogs emerged.

Effect of inbreeding on fertility traits in five dog breeds | Joanna Kania-Gierdziewicz, Sylwia Pałka | Agricultural Journals