Estradiol administration in Holstein heifer calves differentially affects the fatty acid composition of subcutaneous adipose and the mammary fat pad tissues.

Abstract

This research communication reports the relative abundance of fatty acids in mammary fat pad (MFP) and subcutaneous adipose (SCA) tissues for Holstein heifer calves receiving 0, 3, or 12 daily injections of estradiol immediately prior to tissue collection. The objective of this study was to determine if the MFP and SCA fatty acid profiles were affected by estradiol administration and if such a response differs between adipose tissue depots. Twelve Holstein heifer calves were reared on a common diet and administered 12 daily injections prior to euthanasia. Injections were either daily injections of corn oil (n = 4; CON), 9 injections of corn oil followed by 3 injections of estradiol (n = 4; SHORT), or 12 injections of estradiol (n = 4; LONG). Fatty acids were extracted from collected MFP and SCA tissues samples and analyzed using gas chromatography. The MFP tissues contained a greater abundance of saturated fatty acids than SCA tissues which complemented a reduced abundance of mono-unsaturated fatty acids in the MFP than SCA. Extended duration of estradiol administration increased the abundance of total omega 3 fatty acids in both MFP and SCA tissues. There was a treatment by tissue interaction for several of the C18:1 and C18:2 isomers indicating that estradiol's effects on fatty acid uptake and metabolism are tissue specific. Additionally, C18 uptake and metabolisms may have important roles in mammary growth and development. Together, these results indicate that the MFP responds differently to estradiol administration than SCA tissues and that these alterations are associated with different degrees of induced mammary growth via estradiol.