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The experiment was performed on a herd of high-yielding Polish Holstein-Friesian (PHF) cows. The animals were housed in a free-stall barn. They were fed a PMR (partially mixed ration) and were milked twice daily using an automatic milking system. The aim of this study was to determine the yield, proximate chemical composition and mineral content of milk from high-producing primiparous and multiparous cows in successive months of 305-day lactation. Milk yield and the concentrations of fat, protein and selected minerals (potassium - K, sodium - Na, calcium - Ca, magnesium - Mg and zinc - Zn) were analyzed in 305-day lactation. In each month of lactation, older cows were characterized by significantly higher productivity - they reached the highest milk production level (peak yield) in the 2nd month of lactation (51.5 kg of milk), and still produced 26.5 kg of milk in the 10th month of lactation. Milk from multiparous cows had higher protein content than milk from primiparous cows. The average protein content of milk from primiparous cows was lowest (3.01%) in the 2nd month of lactation, and it increased to 3.59% in the 10th month of lactation. Milk fat content was higher in primiparous cows, and it increased from 3.94% (peak yield) to 4.75% in the 10th month of lactation. A wide range of changes in the content of the examined mineral components was noted. In each month of lactation in older cows higher Na and lower Mg content was noted. The low content of Ca in the milk of cows may have been caused by a higher productivity of the analyzed herd. Milk was sampled in successive months after calving during 305-day lactation (360 milk samples from primiparous cows and 840 milk samples from multiparous cows). Milk samples for chemical analyses of the mineral composition (K, Na, Ca, Mg and Zn) were collected individually from cows during test milking, by the classic method - AT4 (Polish Federation... 2017). Data on daily milk yield and the proximate chemical composition of milk were acquired from RW-2 reports (result report from the milk performance assessment). Proximate chemical composition and the concentrations of selected minerals were analyzed in milk from primiparous (group I) and multiparous (group II) cows. The content of K, Na, Ca, Mg and Zn in milk was determined in analytical samples by wet mineralization with a mixture of nitric acid and hydrochloric acid conducted in a MARS microwave digestion system. Mineralized samples were assayed for the mineral content by atomic emission spectrometry (AES) and atomic absorption spectrometry (AAS). Concentrations of the analyzed minerals in milk were read out from calibration curves. [ABSTRACT FROM AUTHOR]

The aim of the work was to assess the fattening capability and slaughter value, including the meat mineral composition, of 3 beef cattle breeds. In the first stage of the experiment, the experimental materials comprised 90 bulls divided into three groups of 30 animals each, representing three beef breeds: Kazakh Hereford (KH), Kazakh Whiteheaded (KW) and imported Hereford (IH). The second stage of the study involved 60 bulls at 450 days of age (± 10 days), 10 bulls of each breed were selected randomly and slaughtered. The tested bulls were fattened from 240 to 450 days and from 450 to 540 days of age, respectively (1st and 2nd stage). The studies showed that the birth weight of bulls was relatively low (slightly above 27 kg) in all groups. Until 240 days of age, imported Hereford bulls were characterized by the highest average daily gains (904 g day-1). At 360 days of age, the average body weight of bulls fattened indoors exceeded 300 kg; Kazakh Hereford bulls had the highest body weight, and differences in the average body weight between groups were statistically significant (p ≤ 0.05). From birth to 450 days of age, the highest daily gain of 810 g was noted in imported Hereford bulls. At 540 days of age, imported Hereford bulls fed indoors (maize silage, hay and concentrate) had the highest average body weight (487.2 kg). In bulls of all breeds, metabolic profile parameters (AST, ALT, ALP, protein, content of Ca, Na, K, Mg and P) remained within the reference ranges, which points to a good health status of animals. Moderate feeding contributed to achieving the highest weight at slaughter by imported Hereford bulls (377.2 kg). Imported Hereford bulls were also characterized by the carcass dressing percentage above 56%, the highest carcass lean content, the lowest carcass fat content and the largest MLD area. Meat from imported Hereford and Kazakh Hereford bulls had the most desirable chemical composition and sensory properties. [ABSTRACT FROM AUTHOR]

The aim of our research was to analyse the composition and the basic content of selected minerals of colostrum depending on the season of calving and lactation of cows. The research material consisted of 180 colostrum samples collected in the first lactation (1st) and further lactation together (FLT) of cows which calved in the summer season (S) and winter season (W). The scope of the experimental research covered determinations performed on colostrum samples collected in 4 lactation phases: 1st (1h), 8th (8h) hour as well as at 3rd (3D) and 5th (5D) day after calving. Studies have shown that the dry matter, fat, protein as well as FFA and IgG content decreased after calving. The lactose level increased and the concentration of urea remained on a relatively constant level (no statistically significant difference). The age of cows was another differentiating factor of the dry matter, fat, protein, FFA, urea and IgG content. It did not affect the change in the lactose content. It has been shown that the content of mineral components changed over the course of the colostral period. The highest values of Ca, Mg and Zn occurred in the first hour after calving, after which their content decreased. The content of K and Na was shaped slightly differently, since it was not possible to establish upward or downward trends. Significant changes also occurred in the content of elements depending on the age of cows. Colostrum with the highest Ca content may be obtained from older cows. However, the highest K, Mg and Na content was recorded in the primiparous cows' colostrum of collected in the first hours after calving. A significantly higher content of K, Mg, Na and Zn appeared in colostrum obtained in the first hour after calving of cows in the winter calving season in comparison to the summer season. [ABSTRACT FROM AUTHOR]

Grass silage is the basic component of diets for winter or year-round feeding of beef cattle in Central and Northern Europe, but its quality can vary considerably. The aim of this study was to determine whether the quality of silage influences the fattening performance of crossbred steers and whether higher intake of supplementary concentrate improves performance in steers fed silage of lower quality. The experiment was conducted on 52 crossbred steers with the initial body weight of 300 kg, produced by crossing Polish Holstein-Friesian dairy cows with Charolais, Limousin and Hereford bulls. The animals had ad libitum access to one of two types of grass silages (of higher and lower quality), and silage intake was recorded individually. Supplementary concentrate consisted of crimped triticale grain (785 g kg-1), rapeseed meal (190 g kg-1) and a mineral-vitamin premix for beef cattle (25 g kg-1). Concentrate was administered at two levels of 1.9 and 2.4 kg dry matter per day. The animals were housed in a free-stall system and feed intake was recorded individually. The fattening period lasted 65 days. Live weight gains were higher (P < 0.0001) in the group of steers fed high feed value grass silage than in the group administered low feed value grass silage. Steers fed silage supplemented with a higher level of concentrate were characterized by higher live weight gains (P < 0.0001) than those receiving silage with a lower level of concentrate. Average daily gains were similar in steers fed lower-quality silage with a higher level of concentrate and in those offered higher-quality silage with a lower level of concentrate (0.972 and 0.975 kg, respectively). It can be concluded that a comparable level of fattening performance can be achieved in steers fed low feed value silage supplemented with a higher amount of concentrate and in animals receiving high feed value silage supplemented with a lower amount of concentrate. [ABSTRACT FROM AUTHOR]

The aim of this study has been to determine the effect of a diet containing β-carotene and omega-3 fatty acids on the biochemical and nonspecific humoral immunity indicators and on the results of rearing calves to day 60 of life. The study was conducted in 2011-2012, on a herd of Polish Holstein- Friesian cows. 54 calves from the herd were divided into 3 groups, 18 animals in each: CTR, TRT1 and TRT2. During the colostral period lasting for 5 days after birth, calves were drinking the mother's colostrum. From 6 to 60 days, calves were watered milk replacer formulation. The control group (CTR) consisted of calves after the colostral period given milk replacer formulation without any supplementation. In the two other groups, calves received milk replacers with the supplementation of β-carotene (TRT1 group) in the amount of 25 mg/calf/day or a suspension of liver omega-3 oil (TRT2 group) in the amount of 5 g/calf/day. All calves received solid feed ad libitum. The research showed that the parameters of the metabolic profile of calves (ALT, ASP, CHOL, GLU, UREA, ALP, TG, CRE) were within the normal range, indicating good health of the calves. Moreover, the supplementation had a positive impact on the chosen immunological parameters, including a higher IgG concentration, especially at the end of the milk drinking period. The result of β-carotene in a diet was the highest daily gain in the period from 30 to 60 days of life among the analysed groups of calves. No such effect was achieved in the TRT2 group of calves, as their body weight was the lowest. However, noteworthy is the beneficial impact of beta-carotene and omega-3 oil on the non-specific humoral immunity parameters, which was manifested by fewer cases of clinical diarrhoea and upper respiratory tract diseases. [ABSTRACT FROM AUTHOR]