Search

The aim of this study was to determine the effect of a cow’s breed on the content of minerals in milk depending on the stage of lactation. The study material was the milk of cows of two breeds, Montbéliarde (mb; n = 15) and black-and-white Polish Holstein-Friesian (phf; n = 15), kept at the same farm. The phf cows were matched with the mb cows by analogs considering the stage and number of successive lactations. Milk for analysis was collected six times during lactation when the official test milking was performed, and a total of 180 milk samples were collected. The fresh milk was analyzed for its proximate chemical composition and mineral content (Ca, Mg, K, Na and Zn), which were identified in the mineralization by flame atomic absorption spectrophotometry. Milk of the Montbéliarde cows contained significantly more sodium, calcium, magnesium and zinc compared to milk of the Polish Holstein-Friesian cows. This enables the conclusion that the contents of these elements are determined by breed. This study demonstrates the variability of the contents of the analyzed minerals with time after calving. During lactation, the contents of potassium, calcium, magnesium and sodium were the highest at the late stage of lactation, especially in the tenth month of lactation.

This study aimed to evaluate the effect of production system and lactation stage (LS) on the yield, centesimal composition, and fatty acid profile of milk from Holstein–Friesian cows. A total of 539 milk samples were collected in winter from cows in six certified organic dairy herds (ODHs) and eight conventional dairy herds (CDHs). The samples were collected randomly from up to 30% of cows at a given stage of lactation (7–45, 46–90, 91–135, 136–180, 181–225, 226–270, 271–315, and 316–360 days after calving). Milk samples were analyzed for proximate composition and the concentrations of fatty acids. The average daily milk yield was 11.4 kg higher (p < 0.01) in CDHs than in ODHs (28.1 kg vs. 16.7 kg). The concentrations of milk fat, protein, and lactose were also higher in CDHs than in ODHs. The fatty acid profile of milk fat was more desirable in ODHs than in CDHs (higher concentrations of polyunsaturated fatty acids (PUFAs), including n-3 PUFAs, trans-vaccenic acid, linolenic acid, and conjugated linoleic acid, and a higher desaturase index). Milk yield decreased (the decrease was more pronounced in ODHs), the concentrations of milk constituents increased, and the proportion of short-chain fatty acids in milk fat decreased (p < 0.05) with advancing lactation.

The aim of this study was to determine the effect of the housing system and somatic cell count (SCC) on the composition and fatty acid profile of milk. A total of 419 milk samples were collected from one herd of 210 cows; 90 cows were kept in the tie-stall system, and 120 cows were kept in the free-stall system. The cows received the same fodder. Samples were collected four times, in winter. Udder health was evaluated based on SCC. The tie-stall system, mainly due to individual care, was superior to the free-stall system. Milk from cows kept in the tie-stall system had lower (p < 0.01) SCC by 72 ths mL−1 cells than milk from cows kept in the free-stall system. An increase in SCC was accompanied by decreases in daily milk yield and lactose concentration. Milk from cows housed in the tie-stall barn had higher polyunsaturated fatty acid (PUFA) contents and a lower n-6/n-3 PUFA ratio. Milk with a higher SCC contained more PUFAs and fewer monounsaturated fatty acids (MUFAs). Tie-stall housing contributed to an increase in the proportions of acids beneficial to the health of consumers. A comparison of two housing systems for cows on one farm showed that the free-stall system was associated with a higher SCC and a less favorable milk composition and fatty acid profile.

Objective The objective of this study was to compare growth performance, carcass traits and meat quality in young bulls, steers and heifers produced by crossing Limousin bulls with Holstein-Friesian cows, fattened semi-intensively and slaughtered at 18 months of age. Methods Thirty-one young calves were reared in a conventional production system, and were fed milk replacer, hay and concentrate. At 6 months of age, the animals were divided into groups based on gender, and were fed a total mixed ration composed of grass silage, concentrates I and II in a semi-intensive production system. At the end of the fattening period (18 months), the animals were slaughtered, carcass quality was evaluated, and samples of musculus longissimus thoracis were collected to determine the proximate composition and quality of meat. Results Bulls were characterized by the highest percentage share of the most valuable cuts in the carcass, and three-rib sections from bull carcasses had the highest lean meat content with low intramuscular fat content (0.93%). No significant differences in carcass conformation, dressing percentage or the percentage share of round in the right half-carcass were found between bulls vs. steers and heifers. Heifers and steers had higher carcass fat content than bulls, which had a positive influence on the sensory properties of beef. In comparison with the meat of bulls, the meat of steers and heifers was characterized by more desirable physical properties and sensory attributes (water-holding capacity, shear force, color lightness, aroma, juiciness, tenderness, flavor). Conclusion Under the semi-intensive production system, heifers and steers had higher carcass fat content than bulls, which had a positive effect on the sensory properties of beef. Bulls are better suited for intensive systems, which contribute to improving the quality of their meat. The results of this study may encourage producers to breed steers and heifers for beef.

This study was designed to compare the fatty acid (FA) profiles of four types of fat depots from crossbred bulls (Polish Holstein-Friesian × Limousin, PHF × LM) fattened semi-intensively (SI) and intensively (I). Intramuscular fat was most abundant in total polyunsaturated fatty acids (PUFAs), n-3 and n-6 PUFAs, and functional fatty acids C 18:2, C 18:3, C 20:4 and C 20:5 in comparison with the remaining fat types. Furthermore, note that external fat was more abundant in conjugated linoleic acid (CLA) than other fat types. Grass silage fed to cattle during fattening had a beneficial influence on the FA profile of beef, and an increase in the amount of concentrate in the ration did not decrease beef quality.

The aim of this study was to determine the effects of genotype and slaughter age on the mineral content and fatty acid profile of beef. The experiment was performed on 72 crossbred bulls produced by crossing Polish Holstein-Friesian (PHF) cows with bulls of three beef breeds: Hereford (HH), Limousin (LM), and Charolais (CH), slaughtered at 15, 18, and 21 months of age. Samples of the longissimus thoracis muscle were collected to determine their mineral (potassium—K, sodium—Na, magnesium—Mg, zinc—Zn, and iron—Fe) and fatty acid composition. The meat of PHF × LM crosses had a lower (p ≤ 0.01) content of K and Mg, compared with the remaining crossbred bulls. The Fe content per kg of meat was 4 mg higher (p ≤ 0.01) in bulls slaughtered at 21 months of age than in those slaughtered at 15 months of age. The content of monounsaturated fatty acids (MUFAs) in intramuscular fat was 2.77% higher in bulls slaughtered at 21 months of age than in those slaughtered at 15 months of age. The n-6/n-3 polyunsaturated fatty acids (PUFA) ratio did not exceed 4.0, and it was most desirable in PHF × LM crosses (2.84) and in the oldest bulls (2.92).

The aim of this study was to evaluate the effect of partial or complete substitution of alfalfa silage with Virginia fanpetals silage in rations based on maize silage on feed intake, digestibility, ruminal fermentation and milk yield and physicochemical characteristics. Nine Polish Holstein Friesian cows in the second half of lactation were fed three experimental diets in a replicated 3 × 3 Latin square design as follows: maize silage + alfalfa silage, maize silage + alfalfa silage and Virginia fanpetals silage in a 50:50 ratio, maize silage + Virginia fanpetals silage. Complete substitution caused an increase in dry matter intake (DMI), total volatile fatty acids (VFA), acetic acid to propionic acid (A/P) ratio, N-NH3 in the rumen contents and milk urea and a decrease in the feed conversion ratio. The partial and complete substitution changed the profile of milk fatty acids, resulting in a slight increase in saturated fatty acids (SFA) and a decrease in unsaturated fatty acids (UFA) as well as in all functional fatty acids except vaccenic acid. The most promising production effects were achieved through partial substitution of alfalfa silage with the Virginia fanpetals silage.

The aim of this study was to determine the effects of the month of lactation and udder health of high-yielding Polish Holstein-Friesian (PHF) cows on daily milk production and the content of K, Ca, Na, Mg and Zn in milk. The experimental materials comprised 380 milk samples collected from 38 cows. The highest average daily milk yield (49.1 kg) was noted in cows in the second month of lactation and, considering udder health, in cows whose milk contained 201,000 to 400,000 somatic cells per mL on average (denoting risk of mastitis). The K content of milk increased (p < 0.05) in successive months of lactation, whereas the opposite trend was observed in the Zn content of milk. The average content of Ca (842 mg∙dm−3), Na (344.5 mg dm−3) and Mg (98.5 mg dm−3) in milk was below the lower limits of the normal physiological ranges. Milk from cows with healthy udders (≤200,000 somatic cells per mL) had the highest concentration of K, whereas the levels of Na and Zn were highest in milk from cows with clinical mastitis (> 1 mln somatic cells per mL). Udder inflammation was accompanied by an increase in the levels of Na and Zn in milk. The high content of Na and Zn in milk can be an additional indicator of mastitis in cows.