Colostrum as a secretion of the mammary gland is produced and accumulated in the final stage of pregnancy and in the first days after calving. It is designed to provide the calf with the necessary nutrients and biologically active ingredients. One of the most difficult periods in the life of animals is their rearing, and the most sensitive are the first days after birth. This is the time when most falls occur, and they are caused by mortality and morbidity, even at the level of 30%. Such losses affect the performance and profitability of animal production (the percentage of animals intended for reproduction or fattening is reduced and the intensity of selection in the herd is also reduced). Both diseases and mortality are the cause of serious economic, production, and breeding losses, which are the result of weak immune mechanisms. The adaptability of calves to the environment is determined by their immune status. Colostrum has a regulating function and stimulates the young organism to grow, and it has properties that support the functioning of systems: Endocrine and immunological. For colostrum to fulfil its role, it must be administered immediately after birth, because the immunoglobulins it contains are absorbed during the first 16–27 h after the birth of the calf, preferably within 2–4 h of age. Blood from calves that have been properly calved should have an antibody concentration of 15g/L (24–48 h of age). Therefore, immunoglobulins are the most important factor affecting infectious immunity; an adequate concentration of immunoglobulins in calves’ blood is related to their survival and health. It is the intent of this review to synthesize and summarize the information currently available on colostrum, as well as to discuss the interpretation of the results.

BackgroundThe aim of this study was to investigate the association between plasma β-hydroxybutyric acid (BHBA) and conjugated linoleic acid in postpartum Polish Holstein-Friesian (PHF) cows. The experiment was carried out at an experimental dairy farm, where a herd of approximately 350 cows was kept. Samples were taken at six time points: between days 5–7, 8–14, 15–21, 22–28, 29–35, and 36–42, resulting in 510 samples of both milk and blood. The cows involved in the experiment were divided into two groups – ketotic and healthy – by taking into account general health symptoms, blood serum BHBA, and non-esterified fatty acids (NEFA) concentration at 5–7 days postpartum.ResultsIn the first week of lactation, at 5–7 day in milk (DIM), the study showed a 53% lower level of C18:2 cis-9 trans-11 (CLA9) and an 80% lower level of C18:2 trans-10 cis-12 (CLA10) in cows with diagnosed ketosis compared to healthy cows. In the second week of lactation (8–14 DIM), a 34% lower level of CLA9 and a 54% lower level of CLA10 was found in the group of cows with BHBA levels > 1.2 mmol/L. Additionally, Pearson correlation analysis showed significant negative correlation between BHBA x CLA9 and BHBA x CLA10 in the first week of lactation: − 0.732and − 0.821, respectively.ConclusionThe study shows that that both CLA9 and CLA10 can be used as markers for the early diagnosis of elevated blood levels of BHBA in postpartum Polish Holstein-Friesian cows.

The main goal of crossbreeding Holstein-Friesian (HF) cows with bulls of other dairy or combined breeds is to improve their performance traits. Thus, the aim of this investigation was to compare the dairy performance traits of first generation crossbreds produced by crossbreeding Polish HF cows with bulls of other breeds (Norman, Norwegian Red, Danish Red, Brown Swiss, Montbeliarde, and Simmental). This was done by analyzing the fatty acid profile and technological quality of the milk from these first generation crossbreds. The investigation showed that crossbreeding greatly influenced the performance parameters and technological quality of the milk of the first generation crossbreds obtained from crossbreeding Polish HF cows with bulls of other dairy or combined breeds. The crossbreed cows characterized by the highest both quantity and quality of milk. Also, the best parameters of milk fat dispersion (that is, the highest values of these parameters) that are useful in the production of hard ripening cheeses and butter were found in the milk of crossbreed cows. Health beneficially, saturated fatty acids level in milk of crossbreeds was by 25.96% lower in crossbreds milk when compared to purebred cows. The most beneficial content of whey proteins was found in the milk of Polish HF and Norwegian Red crosses, where it was 19.04% higher than in pure breed Holsteins. F1 cows tend to express better functional traits than Holstein (PHF) cows. Effect of heterosis was larger and gave better results when there was a greater genetic distance between the animals used for crossbreeding. Keywords: cattle, heterosis, hybrids, milkPractical Application: The effects of heterosis are opposite to the effects of inbreeding depression, and it extends the lifespan and use of animals as well as improves their fertility and health. The main goal of crossbreeding Holstein-Friesian cows with bulls of other dairy or combined breeds is to improve their performance traits. F1 cows tend to express better functional traits than Holstein (PHF) cows. Effect of heterosis was larger and gave better results when there was a greater genetic distance between the animals used for crossbreeding.

The combined supplementation of fish oil and linseed had a positive impact on whey proteins in cow's milk. In addition, the phenotype of β-lactoglobulin also played a role in milk protein composition. There is therefore a clear indication that nutritional experiments should take into account not only food supplements but also the genetic variants of β-lactoglobulin.

The objective of this study was to investigate the effect of carcass weight on chemical characteristics and fatty acid composition of m. longissimus dorsi and m. semimembranosus of European wild boar (Sus scrofa scrofa) meat. The research was carried out on 50 wild boars shot during four battues at hunting reserves in the central part of Poland. The carcasses were divided into three groups: ≤30 kg (G1), 31–45 kg (G2), and >45 kg (G3). The protein concentration increased with carcass weight (P ≤ 0.01). The concentration of saturated fatty acids was influenced by carcass weight and was higher when weight increased. A significantly higher level of monounsaturated fatty acids (MUFA) was found in the carcasses of wild boars from G3 compared with G1 group (P ≤ 0.01). The content of C18:2n-6 was significantly lower in the lightest carcasses compared with the heaviest (P ≤ 0.05). Statistical analysis confirmed that carcasses weight significantly affected polyunsaturated fatty acids (PUFA) n-3 content. The lightest carcasses contained a significantly higher concentration of PUFA n-3 (P ≤ 0.01). In addition, in G3, the amount of C22:5n-3 was two-fold lower (P ≤ 0.01) than in G1. The research has shown that the meat quality was affected by the carcass weight, resulting better parameters in the lighter than in the heavier carcasses. Therefore, most of the culled wild boars should be squeakers and young boars after the first year of life.