Title:	Diet - inducet milk fat depression: Assoication with changes in milk fatty acid composition and fluidity of milk fat.
Authors:	GAMA, M. A. S. GARNSWORTHY, P. C. GRIINARI, J. M. LEME, P. R. RODRIGUES, P. H. M. SOUZA, L. W. O. LANNA, D. P. D.
Affiliation:	Marco Antonio Sundfeld da Gama, Embrapa Gado de Leite; P. C. Garnsworthy University of Nottingham School of Biosciences Loughborough UK; J. M. Griinari University of Helsinki Finland; P. R. Leme, USP; P. H. M. Rodrigues, USP; L. W. O. Souza, USP; Dante Pazzanese Duarte Lanna, ESALQ/USP.
Date Issued:	2008
Citation:	Livestock Science, v. 115, n. 2/3, p. 319-331, 2008.
Description:	This experiment was designed to examine changes in milk fatty acids during fish oil-induced milk fat depression (MFD) and to test the theory that these changes are related to milk fat fluidity. The experiment was divided into three periods: 1) Baseline: all cows (n = 12) received a high fiber diet without fish oil (FO) for 12 days; 2) Treatment: 4 cows/group received the following treatments for 21 days: a) Low fiber diet without FO (LF), b) High fiber diet + FO (HF + FO) and c) Low fiber diet + FO (LF + FO); 3) Post-treatment: cows returned to the baseline diet and were monitored for 12 days. FO was included at 1.6% DM and HF and LF diets had 40 and 26% NDF, respectively. Milk fat content and yield were unchanged by the LF diet, but were reduced by FO diets at both dietary fiber levels and recovered in the post-treatment period. FO diets caused a pronounced reduction in stearic and oleic acid concentrations in milk fat and an equally pronounced increase in trans-18:1 fatty acid concentrations. Milk fat mean melting point (MMP) was correlated with MFD (r = 0.73) and with milk oleic acid concentration (r = − 0.92). The ratio of oleic:stearic in milk fat increased gradually and consistently in response to FO. Trans-C18:1 isomers with double bounds at carbon ≤ 10 increased with greater MFD and those with double bonds at carbon ≥ 11 decreased with greater MFD. Trans-9 cis-11 CLA explained more than 80% of MFD and was strongly correlated with trans-10 C18:1. Maintenance of MMP below 39–40 °C suggests that the mammary gland was able to secrete only milk fat with adequate fluidity and that MFD could be an adaptation mechanism to prevent secretion of milk with higher MMP.
Keywords:	Fish oil Milk fat depression Trans-fatty acids Conjugated linoleic acids Milk fat fluidity
DOI:	https://doi.org/10.1016/j.livsci.2007.08.006
Type of Material:	Artigo de periódico
Access:	openAccess
Appears in Collections:	Artigo em periódico indexado (CNPGL)