The aim of this research was to determine the influence of lactation number and parity on milk yield of Saanen goat’s breed. It has been concluded that milk yield was higher for goats that had given birth to twins and three kids than for goats that had given birth to a single kid (P<0.05). The longevity has a great positive impact on production, given that goats in the fifth lactation produced more milk than goats in first or second lactation (P<0.05), while goats in the sixth lactation still produced more milk than goats in first lactation (P<0.05). During the period from 2014- 2019, the research was conducted on a farm of multiparous Saanen goats in Vojvodina (northern part of Serbia). In the observed period, the farm had between 350 and 400 goats per milking, and the research included a total of 1,628 concluded lactations, within which the first lactations were the most 484, then the second 381. According to the number of lactations, goats were grouped into classes from one to seven and from one to three for parity. By comparing each individual lactation, it was determined that in first lactation goats produced significantly lower milk than goats in the rest lactations(P<0.05), except the seventh. Research has shown that lactation number has a significant influence on milk yield (P=0.00). Increasing the fertility of goats significantly affects the production capacity of dairy goats, since does with a larger number of kids in the litter had a significantly higher milk production (P<0.05). Due to the larger number of kids in the litter, milk production also increases. Likewise, it is assumed that the increase in milk yield of goats with two and three kids is a consequence of a larger placenta, i.e. stronger lactogenic activity during pregnancy.

Milk calcification within mammary acini is an uncommon histopathological finding in dairy cows, potentially affecting glandular function and milk quality. This study aimed to characterize milk calcification in udder quarters of cows removed from production. A total of 104 mammary complexes from 26 cows were examined. Ultrasonography revealed normal parenchymal appearance in all quarters, while histopathology detected calcifications in a substantial proportion of samples. Milk calcification was classified as mild, moderate or severe, ranging from small isolated deposits to massive lumen-filling mineralized masses with epithelial degeneration. Mean somatic cell count (SCC) increased with calcification severity, suggesting a link with the local inflammatory response. The findings indicate that milk calcification may remain undetected by ultrasonography, yet represents a significant pathological alteration in the mammary gland. Histopathological evaluation is essential for accurate assessment of udder health and for understanding the potential impact of mineralized deposits on milk production.

The chemical composition of donkey and sheep milk showed significant differences, with donkey milk containing less fat and protein and a higher level of lactose, while sheep milk had more dry matter and a higher proportion of casein and saturated, unsaturated, monounsaturated, and polyunsaturated fatty acids. This study investigated the biological effects of in vitro-digested donkey and sheep milk, and their blends at different ratios, on differentiated human intestinal Caco-2 cells. Gene expression analysis showed that treatment with digested donkey milk (100%) significantly altered the expression of the autophagy-related gene (SQSTM1), tight junction (CLDN4), and innate defense genes (DEFB1, MUC2, and MUC5), showing a non-cytotoxic response and a profile consistent with a barrier-related transcriptional response. In contrast, sheep milk (100%) and certain milk blends (70% and 50% sheep’s milk) down-regulated genes involved in the autophagy process (ULK1, AMBRA, BECN1, ATG5, GABARAP, and SQSTM1), tight junction genes (OCLN and CDH1), and innate defense genes (DEFB1 and MUC2), suggesting a distinct epithelial response that warrants further confirmation. Metabolomic profiling revealed clear compositional and functional distinctions among the digested milks, identifying 166 metabolites that were differentially regulated (136 compounds were down-regulated and 30 up-regulated). Donkey milk digestion yielded a metabolite profile enriched in polar peptides and compounds with reported antioxidant associations, whereas sheep milk digestion showed a different pattern dominated by hydrophobic peptides and lipid-related metabolites. These findings indicate that, under the tested in vitro conditions, donkey milk digestion is associated with gene expression and metabolomic patterns consistent with epithelial barrier support.

The aim of this study was to evaluate the relationship between serum zinc concentration, teat canal keratin layer thickness and somatic cell count (SCC) in dairy cows. The study included 26 dairy cows excluded from production and sent to slaughter, with a total of 104 udder quarters examined. Prior to slaughter, blood samples were collected for determination of serum zinc concentration and milk samples from each udder quarter were obtained for SCC analysis. After slaughter, teats were collected for histopathological examination and the thickness of the teat canal keratin layer was measured. A significant negative correlation was observed between serum zinc concentration and SCC (r = -0.62, p < 0.01), indicating that higher serum zinc levels were associated with lower SCC values. Serum zinc concentration was positively correlated with teat canal keratin layer thickness (r = 0.58, p < 0.01), while keratin layer thickness showed a significant negative relationship with SCC (r = -0.54, p < 0.05). The lowest SCC values were recorded in teat canals with a keratin layer thickness of 201-300 μm, whereas higher SCC values were found in canals with both very thin (0-100 μm) and excessively thick (301-400 μm) keratin layers. These results indicate that adequate serum zinc concentration and optimal teat canal keratin layer thickness are associated with improved udder health and lower SCC values, suggesting a potential role of zinc status and teat canal integrity in reducing the risk of subclinical mastitis in dairy cows.

Summary: Nutrition is considered the primary paragenetic factor influencing the milk urea (MU) concentration in ruminants. In addition to diet, various other factors (including season, milk yield, stage of lactation, etc.) have also been shown to affect the urea concentration in ruminant milk. While the physiological concentration of MU has been well-defined for cow's milk, with an optimal range of 15 to 30 mg/dl, such parameters have yet to be established for goat's milk. The objective of this study was to determine the urea concentration in the milk of Alpine goats and to assess its correlation with the daily milk yield and the contents of fat, protein, lactose, and solids-not-fat (SNF). A total of 3,009 samples of Alpine goat milk, collected from two farms in 2021, were analyzed. The average MU concentration was 37.3 ± 8.9 mg/dl, with a range from 13.8 to 110.7 mg/dl. The average daily milk yield was 1.15 ± 0.49 kg, whereas the average milk fat and protein contents were 3.28 ± 0.97% and 3.35 ± 0.50%, respectively. The study found a positive and statistically significant correlation between the MU concentration and the contents of milk fat, protein, and SNF. Conversely, an increase in the MU concentration was negatively correlated with the daily milk yield. Monitoring the MU concentration in dairy goat herds enables the optimization of feed rations, particularly their protein and energy contents, thus improving nitrogen utilization in milk production.