Beata Sitkowska

Milk protein polymorphisms and effect of herds on cows` milk composition

Kappa-casein (CSN3) and beta-lactoglobulin (LGB) loci affect milk yield traits and the quality of milk protein. Their polymorphisms explain the role of genetic variance and facilitate estimation of breeding value. Our research was aimed at estimating the effect of beta-lactoglobulin and kappa-casein genotypes on milk yield and the chemical composition of milk, for cows bred in three herds in the kujawsko-pomorskie province. We divided the cows into three groups depending on their beta- lactoglobulin and kappa-casein polymorphisms: AA, AB and BB. The percentage of AB LGB heterozygotes in the examined population was the highest, at 44%; whereas the frequency of both gene alleles was at a similar level. In the kappa-casein gene, we found that there was a predominance of AA CSN3 genes (0.69), and a small percentage of BB CSN3 genotypes (0.07). We also observed a higher frequency of the A allele (0.81) as compared to the B allele (0.19), which is desired in breeding. Analysing the influence of the examined factors, we established a statistically significant influence of the barn as well as interactions between the barn and the LGB and CSN3 genotype on the percentage of fat and protein in milk from all examined lactations. Milk yield is influenced by the interaction between examined genotypes and the LGB genotype. The highest fat and protein content in the first lactation was found in animals with the AB LGB genotype: 4.53% of fat and 3.41% of protein. In lactations 2 and 3, the highest values for these parameters were noted for cows with the AA LGB genotype. As to the kappa-casein gene, we observed that cows with the AA CSN3 genotype constituted the largest group. Heterozygous animals produced the highest amount of milk with higher fat and protein yield as compared to the other groups.

The influence of selected genes on sheep performance traits.

In order to enhance breeding progress, genes that affect the performance of sheep are being identified. In Poland, sheep breeding programs focus mainly on meat performance, therefore, it is important to identify genes that affect it. Moreover, studies on reproductive performance of sheep have been made. Myostatin (GDF8), calpastatin (CAST) and calpain have been identified as the candidate genes affecting meat quality. Whereas, BMP15 and GDF9, also called fertility genes (Fec), have been reported to affect reproduction traits. The knowledge of the association between the polymorphic forms of these genes and sheep performance traits may contribute to the determination of genetic markers that could be used in sheep breeding programs. The aim of this study is to gather the latest information about the use of genomic selection in breeding programs and the association between polymorphisms in BMP15, GDF8, GDF9 and CAST genes and sheep performance.

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.

ENVIRONMENTAL AND HEALTH PARAMETERS OF BEEF AND MILK CATTLE MEASURED WITH THE USE OF SURVEYS

The objective of the study was to determine parameters related to cattle’s health and the environment in which they live in cowsheds oriented at beef and milk production. The study included 70 cattle breeders from the pilskie county, Wielkopolskie province. Twenty of the surveyed farmers produced milk, 31 beef, and 19 produced both. The majority of the surveyed farmers worked on family run farms: taking up the area of up to 50 ha and the with up to 50 animals. Approximately 70% of the surveyed farmers kept their animals tethered. Only more or less 40% declared they owned a designated isolation area. Automatic drinkers were, unsurprisingly, present mostly at farms where either milk or both milk and beef were produced (over 60%). Deworming was significantly more frequent on farms producing only beef (68.97%). Measurements of the intensity of harmful gases, airflow speed, humidity, and lighting intensity were conducted in only few cowsheds (up to 9% of the analysed). The results of our study point to greater need of education among farmers, and improving environmental conditions in which cattle are maintained.

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.