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Lipid peroxidation can be described as a process under which free radicals attack carbon double bonds of omega-3 and omega-6 fatty acids. Whereas the end products of this process are reactive aldehydes, such as malondialdehyde (MDA). Lipid peroxidation leads to adverse changes in the nutritional value of milk; therefore, higher degree of antioxidant protection (DAP) ensures higher stability of dairy products by effecting their high antioxidative potential. Therefore, the purpose of this study was to demonstrate the relationship between the DAP and the level of MDA in high-performance Polish Holstein-Friesian cows in peak of lactation. Sixty-three Polish Holstein-Friesian cows were selected to the experiment according to: parity (all in the 2nd lactation), phase of lactation (peak of lactation), cytological quality of milk (somatic cell count < 150 thousand/ml) and without diagnosed metabolic diseases. The data obtained were analyzed statistically by two-way ANOVA, and Tukey's post-hoc test. After analysis of performance the cows were divided into 3 groups (twenty one cows in each group) based on milk yield and MDA concentration. The study revealed a significant effect of the lactation performance of cows on MDA levels in milk (P ≤ 0.01). The highest concentration of MDA (61.137 nM/mL) was shown in milk of cows yielding between 50.00 and 55.80 kg/day. The highest concentration of fat was found in milk in which the MDA level ranged from 48 to 86 nM/mL. Whereas, the inverse relationship was demonstrated in case of protein concentration. The highest level of protein was found in cows with MDA levels in the range of 18-28 nM/mL (P ≤ 0.01). The lowest MDA level (in the range of 18-28 nM/mL) was associated with the highest concentration of vitamin E, β-carotene, total antioxidant status (TAS) and DAP, measured in both milk and plasma. The obtained results show that lipid peroxidation leads to adverse changes in the nutritional value of milk; the highest DAP (7.89 x 10-3) was found in the cows with the lowest MDA concentration in milk.

In lactating dairy cows, negative energy balance (NEB) induces metabolic shifts, including enhanced lipolysis, leading to elevated concentrations of free fatty acids (FFAs) in circulation. Metabolic changes affect milk fat synthesis and the characteristics of milk fat globules (MFGs), particularly their size and distribution. Systemic FFA release inversely correlates with the restoration of the body condition score (BCS), suggesting that recovering the BCS may mitigate the negative effects of NEB on milk fat composition. This study aimed to investigate the relationship between BCS restoration, metabolic burden, and their effects on MFG characteristics in lactating cows. The study was conducted on two dairy farms (F1 and F2) with 80 Holstein-Friesian cows. Cows were grouped according to farm and diet, with average lactation yields of 9653 ± 259 kg (F1) and 9548 ± 341 kg (F2). Milk composition was analyzed, and blood and milk samples were collected at four lactation stages. The results showed a significant correlation between elevated circulating FFA concentrations, resulting from adipose tissue lipolysis during NEB, and alterations in MFG size and distribution. The restoration of BCS was inversely correlated with FFA release, suggesting that improvements in the BCS may mitigate the adverse effects of NEB on milk fat synthesis by regulating lipolysis. Additionally, higher β-hydroxybutyrate (BHBA) levels were associated with a reduction in MFG diameter, indicating disruptions in lipogenesis during metabolic stress. These findings highlight the complex relationship between metabolic stress, BCS restoration, and MFG characteristics, with implications for milk fat synthesis in lactating cows.

Maintaining a high level of beef consumption requires paying attention not only to quantitative traits but also to the quality and dietary properties of meat. Growing consumer demands do not leave producers many options for how animals are selected for breeding and animal keeping. Meat and carcass fatness quality traits, which are influenced by multiple genes, are economically important in beef cattle breeding programs. The recent availability of genome sequencing methods and many previously identified molecular markers offer new opportunities for animal breeding, including the use of molecular information in selection programs. Many gene polymorphisms have thus far been analyzed and evaluated as potential candidates for molecular markers of meat quality traits. Knowledge of these markers can be further applied to breeding programs through marker-assisted selection. In this literature review, we discuss the most promising and well-described candidates and their associations with selected beef production traits.

The aim of this study was to determine the effect of supplementing rations, with a mixture of fish oil and linseed, on the level of immunomodulatory components in colostrum. Twenty multiparous cows, that were three weeks before scheduled calving, had a body condition of 3–3.5, and had not been diagnosed with multiple pregnancies, were qualified for the experiment. The cows were divided into two groups: experimental (FOL) (n = 10) and control (CTL) (n = 10). The CTL group were individually given the standard food ration for dry cows for about 21 days before calving, while the FOL group received food rations that were enriched with 150 g of fish oil and 250 g of linseed (golden variety). Colostrum samples for testing were taken twice a day on the first and second days of lactation, and then once a day from the third to the fifth day of lactation. The experiment showed that the applied supplementation had an impact, in the form of increasing the fat, protein, IgG, IgA, IgM, vitamin A, C22:6 n-3 (DHA), and C18:2 cis9 trans11 (CLA) contents in colostrum; however, the C18: 2 n-6 (LA) and C20:4 n-6 (AA) contents decreased. Due to the lower quality of colostrum found in high-yield cows, and therefore in the Holstein–Friesian breed, it is possible to improve the quality by, among other things, introducing nutritional modifications during the second stage of the dry period.

Negative energy balance (NEB) during early lactation links spontaneous lipolysis (SL) with inflammatory signaling, yet the molecular response in dual-purpose breeds remains insufficiently characterized. This study investigated how NEB regulates circulating concentrations of interleukin-6 (IL-6) and plasminogen (PL) in Simmental cows, contextualizing these changes within concurrent metabolic adaptation. Forty-two cows were monitored from approximately two weeks prepartum to 150 days in milk across six defined stages. Energy balance (EB) was calculated from feed intake and energy-corrected milk yield, while daily milk production (DMP), milk composition, body condition score (BCS), β-hydroxybutyrate (BHBA), glucose (GLU), leptin (LEP), selected fatty acids (FAs: C16:0, C18:0, C18:1-t9, C18:2, IL-6), and PL were determined. EB declined progressively as DMP increased (r = -0.689, ≤ 0.05). During peak NEB (SLII-SLIII), IL-6 increased from 92.16 to 109.59 ng·L and PL from 1.65 to 2.05 ng·L , both inversely correlated with EB (r = -0.741 and -0.586, respectively) and positively associated with each other (r = 0.728), indicating coordinated activation of cytokine and fibrinolytic pathways. NEB severity was accompanied by elevated BHBA and LEP, decreased GLU, reduced BCS, and increased circulating FAs; nevertheless, ketosis remained moderate (peak BHBA 1.04 mmol·L ). These findings demonstrate that Simmental cows display a breed-specific molecular response in which NEB modulates IL-6 and PL in parallel with controlled lipid mobilization and efficient hepatic metabolism, supporting enhanced metabolic resilience during early lactation.

The impact of cow mammary gland diseases on the quality of colostrum is not conclusively defined; research results are conflicting. However, it is widely believed that mastitis lowers the level of immunoglobulins and the quality of the colostrum produced. Therefore, the aim of this study was to determine the influence of somatic cell counts (SCC) on the colostrum immuno-stimulating and chemical components. The experiment was conducted on an experimental organic dairy farm in which a herd of approximately 250 cows was kept in a freestall housing system, with the average performance exceeding 6,000 kg of milk per lactation. Colostrum and milk samples were taken individually from each cow seven times during the experiment: from the first to second day after calving–twice per day, and from the third to fifth day after calving–once per day. Therefore, after preliminary analyses, the cows were divided into two groups based on the cytological quality of their colostrum at the first collection: 1. SCC 400,000 cells/ml (good quality colostrum; GCC– 18 cows), 2. SCC 400,000 cells/ml (low quality colostrum; LCC– 22 cows). The study found almost double the concentration of immunoglobulins and essential fatty acids in first milking colostrum in the GCC group than in colostrum from the LCC group. In addition, an increase in the concentration of lysozyme in first milking colostrum was associated with a decrease in the concentration of immunoglobulins. In addition, the increase in the level of lysozyme was associated with a decrease in the concentration of immunoglobulins. In conclusion, the SCC of first milking colostrum can be used as an indicator of colostrum quality.

β-lactoglobulin is one of the most abundant milk whey proteins in many mammal species, including the domestic horse. The aim of this study was to screen for polymorphism in the equine LGB1 and LGB2 gene sequences (all exons, introns, and 5'-flanking region) and to assess potential relationship of particular genotypes with gene expression levels (measured in milk somatic cells) and milk composition traits (protein, fat, lactose, and total β-lactoglobulin content). Direct DNA sequencing analysis was performed for twelve horse breeds: Polish Primitive Horse (PPH), Polish Coldblood Horse (PCH), Polish Warmblood Horse (PWH), Silesian, Hucul, Fjording, Haflinger, Shetland Pony, Welsh Pony, Arabian, Thoroughbred, and Percheron-and revealed the presence of 83 polymorphic sites (47 and 36 for LGB1 and LGB2 genes, respectively), including eight that were previously unknown. Association analysis of the selected polymorphisms, gene expression, and milk composition traits (conducted for the PPH, PCH, and PWH breeds) showed several statistically significant relationships; for example, the two linked LGB1 SNPs (rs1143515669 and rs1144647991) were associated with total milk protein content (p < 0.01). Our study also confirmed that horse breed had significant impact on both gene transcript levels (p < 0.01) and on milk LGB content (p < 0.05), whereas an influence of lactation period was seen only for gene relative mRNA abundances (p < 0.01).

Background/Objectives: The negative energy balance activaties of spontaneous lipolysis. This may promotes inflammation within the adipose tissue. The aim of the study was to explain the development of inflammation during increased lactogenesis. It was hypothesized that lipolysis contributes synthesis of interleukin-6 and plasminogen. Methods: The study was in production conditions carried out using Holstein-Friesian cows. The period studied covered time of early lactation. Results: Up to the peak of lactation, milk yield strongly influenced the rate of loss of body condition. This had an impact on with the intensity of the release of the fatty acids. In both cases this relationships strengthened to the peak of production. Oobserved tendencies towards a decrease in the concentration of glucose and an increase in that of leptin. Loss of the body condition and the release of NEFA were were influencing to affect the blood concentrations of interleukin-6 and plasminogen. We have shown that IL-6 has a relatively strong correlation with the NEFA. They correlate with IL-6 independently of EB influence. This may suggest independent associations between these variables, which could potentially be applied in practice. Conclusions: The NEFA release in the long term can increase the inflammatory response within adipose tissue and can intensify the release of interleukin-6 and plasminogen. It is likely that in the initial stage of lactogenesis, the inflammatory process developing within adipose tissue is physiologically justified. Our results can provide background to this little-described area of research.

The aim of this study was to investigate the association between immunoglobulins and SCC as a factor in shaping the content of the immunostimulatory components of colostrum. Seventy-eight multiparous Polish Holstein–Friesian cows were selected for the experiment. Colostrum samples were collected immediately after calving (up to a max. of 2 h). The cows were divided into groups according to the following levels: Immunoglobulins (IG class)—(IG 1 ) over 50 g/L, (IG 2 ) up to 50 g/L; SCC class—(SCC 1 ) up to 400 000/ml, (SCC 2 ) 400–800 000/ml, (SCC 3 ) over 800 000/ml. Colostrum assigned to the IG 1 SCC 1 group had a statistically significant higher (p ≤ 0.01) concentration of both whey proteins and fatty acids compared to the IG 1 SCC 2 and SCC 3 groups. The concentration of IgG, IgM, and IgA was shown to be higher in IG 1 SCC 1 than IG 2 SCC 3 by 226%, 149%, and 115%, respectively. The concentration of lactoferrin was shown to be higher in IG 1 SCC 1 than IG 2 SCC 3 by 149%. The determination of colostrum quality based on the concentration of immunoglobulins in the colostrum may not be sufficient because serum IgG concentrations at birth show a linear increase relative to colostrum SCC. A breakdown of colostrum into quality classes, taking into account the level of SCC, should therefore be introduced.

This study involved 30 male pigs (DanBred × Duroc), which were divided into three groups of 10 animals each. Control group (C)—immunologically castrated boars with a slaughter weight of 120 kg; and experimental groups: E1—uncastrated boars with a slaughter weight of 120 kg, and E2—uncastrated boars with a slaughter weight of 105 kg. Animals from all groups were fed a complete feed mixture in a liquid form three times a day. After slaughter, their meat and backfat were analysed for the physicochemical parameters and for the contents of indole, skatole, androstenol, and androsterone. A higher protein content was determined in the meat of boars from group E1 (23.48%) compared to those from groups C (22.87%) and E2 (22.99%) (p ≤ 0.01), and a higher content of n-6 PUFAs in the meat of boars from group C (5.21 mg/g of meat) compared to those from group E2 (4.81 mg/g of meat) (p ≤ 0.05). Analysis of the chemical composition of backfat showed a lower protein level in the backfat of boars from group C (4.70%) compared to those from group E1 (6.20%) and a higher fat level in the backfat from boars from group C (70.09%) compared to those from groups E1 (65.90%) and E2 (64.75%) (p ≤ 0.05). Body weight and immunocastration status were also shown to affect the fatty acid profile. Immunocastration also reduced the content of androstenol and androsterone in meat and fat. A higher content of indole was demonstrated in the meat of boars from group C and in the backfat of those from group E2 compared to the animals from the other groups (p ≤ 0.001).