Milk fatty acid composition has gained the interest of both manufacturers and consumers during recent years. The present paper aimed to perform an analysis of C14:0, C16:0, C18:0, C18:1, saturated (SFA), monounsaturated (MUFA), polyunsaturated (PUFA) and short chain fatty acid (SCFA) concentration in cow’s milk in relation to the type of ration, parity, lactation phase and season. Cows’ milk from animals being fed total mixed rations, including corn silage, had higher C14:0, C16:0 and SFA concentrations than those being fed pasture-based rations but lower concentrations of C18:0 and PUFA. Comparing to 1st parity cows, 2nd and 3rd parity animals had higher SFA and SCFA concentrations in milk. With respect to spring, C14:0, C16:0 and SFA concentrations increased in summer, autumn and winter while MUFA, PUFA and SCFA concentrations decreased. Considering the lactation phase, C14:0, C16:0 and SFA concentrations decreased in fresh cows with ketosis comparing to healthy fresh cows and increased in peak, mid and late lactation. C18:0, C18:1 and MUFA follow the opposite trend. The milk fatty acid profile varies significantly through the studied effects. The fact that the fatty acid profile is associated with animal health, organoleptic properties of milk or even methane production highlights the importance of studying factors that affect its variation.

This study analyses the effect of heat stress (HS) on milk production, composition, and somatic cell count in Holstein cows in Galicia. For this purpose, the study uses the temperature and humidity index (THI) obtained from the official network of weather stations and data from the official milk control between 2016 and 2021. For milk production, critical THI thresholds were established at THI = 72, while the somatic cell count increased when THI exceeded 78. For the fat and protein components of milk, the critical thresholds are lower, at 64 and 63, respectively. The analysis shows that for each unit increase in THI above the critical threshold, up to 0.249 kg of milk, 0.008 kg of protein, and 0.006 kg of fat can be lost per cow per day. HS has a greater impact on milk composition than on volume, particularly on protein content. In addition, it was observed that the impact of HS on milk production can last between 7 and 12 days. Similarly, consecutive cumulative days of HS significantly impact both milk production and quality, especially in higher productivity stages multiparous cows. Although Galicia has a less extreme climate than other regions, the presence of moderate HS during the warmer months causes significant economic losses in the dairy sector.

This study assessed trace mineral levels (Co, Cr, Cu, Fe, Mn, Mo, Se, and Zn) in paired serum samples from multiparous Holstein Friesian cows and their calves after colostrum intake, to explore potential relationships between maternal and neonatal mineral status. The acid-digested samples were analyzed by inductively coupled plasma mass spectrometry. Serum levels of Co, Cu, Fe, and Se were significantly higher in cows than in calves (p < 0.001), while Zn levels were higher in calves. The levels of Cr, Mn, and Mo were similar in both groups. Overall, mineral deficiencies were more prevalent in cows, with Se being the most deficient element, followed by Zn, Cu, and Co. Calves were more deficient in Co and Mn than their mothers but were not generally deficient in Se. Serum levels of Cr, Cu, Mn, Mo, and Se were positively correlated in cows and their calves, suggesting that maternal mineral status influences neonatal mineral levels. Overall, these results provide insights into trace mineral dynamics in cow–calf pairs. Further studies are needed to clarify the relative contribution of placental and colostral mineral transfer.