PSVII-19 Fatty acid profiles in subcutaneous adipose and the mammary fat pad of Holstein calves receiving different estradiol treatments

Abstract

Abstract Estradiol administration increases mammary parenchyma growth and can increase the mass of the mammary fat pad (MFP) in calves. Estradiol can affect fatty acid metabolism, but it is unknown how estradiol affects the fatty acid profile of the MFP and if these effects are consistent across adipose stores. The objective of this investigation was to determine if fatty acid profiles were affected by estradiol administration and if this response is adipose tissue type specific. Holstein heifer calves were reared on a common diet and administered 12 daily injections prior to euthanasia at 82 days of age. 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 MFP and subcutaneous adipose tissues samples and analyzed using gas chromatography. Data were analyzed using a mixed model considering the effect of treatment, adipose tissue depot, their interaction, and the random effect of animal. Only significant treatment effects and treatment-adipose type interactions are presented here (Table 1). Estradiol administration (SHORT and LONG) increased total C18:1 fatty acids (P = 0.05), and tended to increase non-C18:2 t10 c12 CLAs, C18:3, and total omega-3 fatty acids (P ≤ 0.1) in the MFP and subcutaneous adipose tissues relative to CON. There was a treatment by tissue interaction for C18:1 trans-10 (P = 0.01), and a tendency for C18:1 trans-11 and C18:2 trans-10 cis-12 (P ≤ 0.1) indicating that estradiol’s effects on fatty acids are tissue specific. Together, these results indicate that the MFP responds differently to estradiol than subcutaneous adipose tissues and that these alterations are associated with different periods of induced mammary growth via estradiol.