Heat stress is a major challenge for dairy farmers, as it can have a significant impact on milk production. The purpose of this research was to investigate the differences in the compositions of colostrum and mature milk from various animal species (Aberdeen Angus cows (AC), Baladi cows (BC), and Baladi goats (BG)) under a desert climate in the New Valley Governorate, southwest Egypt. The physicochemical properties, protein fractionations, fatty acid composition, and vitamin A and cho-lesterol contents of AC, BC, and BG were evaluated. The studied species had higher total solids, fat, protein, ash, minerals, whey proteins, and vitamin A (IU/g) in colostrum than in mature milk. The colostrum and milk of BG had the highest vitamin A and cholesterol content in comparison with those of AC and BC. The content of κ-casein in milk decreased, while the content of αs-casein increased. Additionally, the band for αs2-CN was stronger than that for αs1-CN in milk from different species. In comparison to BC and BG milk, the αs1-CN band in BG milk was weaker. However, the bandwidth of β-CN was smaller in milk and stronger in all colostrum bands. In cow milk, the amount of β-casein was lower than that in goat milk. Colostrum from different species had higher concentrations of β-LG and α-LA than milk. The levels of short-chain fatty acids (SCFA), branched-chain fatty acids (BCFA), long-chain fatty acids (LCFA), and polyunsaturated fatty acids (PUFA) were lower in colostrum than in mature milk, while the amount of monoun-saturated fatty acids (MUFA) was higher.