Milk Fatty Acid Profile and Production Traits in Lithuanian Local and Holstein Cattle Breeds

White-backed and Ash-grey cows yielded an average of 6212 kg and 6078 kg of milk per year, with 4.25-4.28% fat and 3.37-3.40% protein, while Holsteins averaged 10,694 kg with 4.47% fat and 3.45% protein. The study aimed to analyse the fatty acid (FA) profile of milk from two local cow breeds, compare them with that of Holstein cows, and evaluate the influence of lactation number, productivity indicators and milk colour. The study was carried out with White-backed (n = 40), Ash-grey (n = 49), and Holstein (n = 51) cows. Based on lactation number, cows were divided into two groups. Composite milk samples from all quarters of each cow were collected. Two additional milk samples were taken: 1st to assess milk colour and the second to determine the fatty acids profile. Productivity data of cows were provided from the Livestock Information System. Statistical analysis included calculating means and standard deviations or standard errors of the mean. One-way and two-way ANOVA (breed and lactation) were used, and Duncan's test was applied to compare mean values between groups. White-backed cows contained greater proportions of C17:0, C17:1, C18:3 ω3, and C20:0 (p < 0.05), as well as higher total omega-3 and polyunsaturated fatty acid (PUFA) contents. Parity did not have a significant effect on productivity indicators, but parity influenced the FA profile. Milk from 1st-lactation Ash-grey cows showed higher levels of PUFA and omega-6 fatty acids (p < 0.05). Milk from Ash-grey cows has more favourable visual attributes, indicating improved suitability for dairy processing, where colour uniformity is important for technological quality.