Dariusz Piwczyński

Heritability and breeding value of sheep fertility estimated by means of the gibbs sampling method using the linear and threshold models.

The research was carried out on 4,030 Polish Merino ewes born in the years 1991- 2001, kept in 15 flocks from the Pomorze and Kujawy region. Fertility of ewes in subsequent reproduction seasons was analysed with the use of multiple logistic regression. The research showed that there is a statistical influence of the flock, year of birth, age of dam, flock × year interaction of birth on the ewes’ fertility. In order to estimate the genetic parameters, the Gibbs sampling method was applied, using the univariate animal models, both linear as well as threshold. Estimates of fertility depending on the model equalled 0.067 to 0.104, whereas the estimates of repeatability equalled respectively: 0.076 and 0.139. The obtained genetic parameters were then used to estimate the breeding values of the animals in terms of controlled trait (Best Linear Unbiased Prediction method) using linear and threshold models. The obtained animal breeding values rankings in respect of the same trait with the use of linear and threshold models were strongly correlated with each other (rs = 0.972). Negative genetic trends of fertility (0.01-0.08% per year) were found.

Impact of successive lactation, year, season of calving and test milking on cows' milk performance of the Polish Holstein-Friesian black-and-white breed.

The research was conducted based on 8895 test milkings of 463 milk cows calving first time in 2003 and reared in the Pomorze and Kujawy region. The aim of the present study was to analyse the influence of selected factors on the milk performance and its chemical composition. A statistical influence of a herd, season and year of calving, a season of test milking, lactation on milk performance traits was analysed using a multiple variance analysis. The milk performance, its chemical composition and quality altered considerably depending on the season of calving, season of test milking and successive lactation. The highest percentage amount of milk and its components was obtained from cows calving in spring months. In turn, the highest content of fat, protein, lactose and dry matter occurred in the samples collected from the cows calving in the summer milking period. The highest amounts of milk were collected in the summer period, and the lowest – in the winter period (these dissimilarities proved highly significant). The highest amount of calculated FCM and ECM, fat (kg) and lactose was collected from cows in their first lactation, whereas the lowest from those in their fourth lactation.

OPINIONS EXPRESSED BY CATTLE BREEDERS ON HUMAN-ANIMAL RELATIONS AND THE CONDITIONS IN WHICH ANIMALS ARE KEPT

The survey included 69 Polish farmers running private farms which focus on cattle breeding. Based on the survey results, and answers given by dairy and beef cattle breeders, it was found that the majority of respondents present the right attitude towards animals, and that they understand the influence of the person being in charge of a herd on the behaviour of animals and production results. The majority of the surveyed breeders continue to keep their cattle in stall barns, with more than 70% believing that this system provides good conditions for animals, and approximately 10% believe this is the best system possible. Approximately 80% of breeders is of the opinion that the animal housing system used has an effect on the condition of animals’ legs. The majority of breeders say that their animals are kept in either good or very good environmental conditions.