The objective of this study was to evaluate the effect of whole cottonseed on diets of cows under grazing on fatty acid profile and milk cholesterol. Five crossbred Holstein × Zebu cows were distributed in a 5 × 5 Latin square. Inclusion levels were 0, 6, 12, 18 and 24%. There was a linear decrease in all fatty acids quantified, saturated and monounsaturated (p > 0.05), possibly due to the action of polyunsaturated fatty acids ingested in the diet. There was no influence of treatment on conjugated linoleic acids or cholesterol. It is concluded that, regardless of inclusion level, there is a modification in the milk lipid profile, reducing the concentration of saturated fatty acid, monounsaturated fatty acid, and making it rich in polyunsaturated fatty acids, which are beneficial to health.

O estudo mostra a ação sucessiva dos tratamentos térmicos de pasteurização (75 ºC por 15 s) e esterilização comercial por troca indireta de calor (140 ºC for 6 s) sobre o perfil lipídico de leite bovino. Amostras de leite cru foram submetidas à pasteurização e então, à esterilização comercial (ultra-alta temperatura, UHT). A gordura de amostras de leite cru, de leite pasteurizado e de leite esterilizados comercialmente foi extraída. Após transesterificação, os ésteres metílicos dos ácidos graxos (FAMEs) foram analisados por cromatografia gasosa com detecção por ionização de chama (GC-FID). A quantificação revelou que para a maioria dos ácidos graxos (FA) encontrados não houve diferença significativa (p > 0,05) entre as amostras de leite cru e leite pasteurizado. Entretanto, foram encontradas diferenças significativas para 21 dos 26 ácidos graxos analisados (p > 0,05) para as amostras de leite cru e de leite esterilizado, incluindo o isômero predominante no leite do ácido linoléico conjugado (CLA-c9t11). Este fato evidencia a ação sucessiva dos tratamentos térmicos no perfil lipídico do leite.

The action of successive pasteurization thermal treatments (75 ºC for 15 s) and commercial sterilization by indirect heat exchange (140 ºC for 6 s) was analyzed on the lipid profile of bovine milk. Raw milk samples were submitted to pasteurization and then were submitted to sterilization (ultra-high temperature, UHT). The fat of raw milk, pasteurized milk and commercially sterilized milk samples was extracted. After transesterification, the fatty acid methyl esters (FAMEs) were analyzed by gas chromatography with flame ionization detector (GC-FID). The quantification of fatty acids (FA) revealed that for most of the found fatty acids there was no significant difference (p > 0.05) between raw milk and pasteurized milk. However, it was found significant differences for 21 of the 26 analyzed fatty acids (p > 0.05) for the raw and sterilized milks, including the predominant isomer of the conjugated linoleic acid (CLAc9t11) of the milk. This fact evidences the successive action of heat treatments on milk lipid profile.