The fatty acid profile of subcutaneous and abdominal fat in dairy cows with left displacement of the abomasum

Abstract

The objective of this study was to determine the fatty acid (FA) profile and assess desaturase indices of nonesterified fatty acids (NEFA) in the blood, as well as in the abdominal (ABD) and subcutaneous (SUBC) fat stores, in dairy cows with left displacement of the abomasum (LDA). Blood, ABD, and SUBC samples were taken from 50 Holstein cows offered for surgery to correct LDA. The FA profile of the 3 compartments was determined by gas chromatography after lipid extraction, methylation, and, in the case of blood plasma, separation of lipid classes. The most abundant FA in all 3 compartments were 16:0, 18:0, and 18:1 cis-9, with a total proportion of 82.5, 68.0, and 74.1g/100 g of FA in ABD, NEFA, and SUBC, respectively. A principal component analysis was performed on the entire FA profile as well as on the Δ(9)-desaturase indices (14:1 cis-9/14:0, 16:1 cis-9/16:0, 18:1 cis-9/18:0). The principal component analysis extracted 2 principal components (PC), representing 51.6% (PC1) and 21.1% (PC2) of the total variance in FA composition of the 3 compartments. The loading plot for the regression factors revealed a strong positive correlation between PC1 with the Δ(9)-desaturase indices and the proportions of 14:1 cis-9 and 16:1 cis-9, and revealed a negative correlation with the proportion of 18:0 and saturated FA. The correlation with PC2 was positive for the proportion of unsaturated FA, 18:2n-6, and 18:3n-3, and negative for the proportion of 14:0, 16:0, and saturated FA. The SUBC could be distinguished from the NEFA and ABD by a positive score for PC1, whereas differentiation among the latter 2 compartments could be made by a positive (NEFA) or negative (ABD) score for PC2. The Δ(9)-desaturase indices for C14 and C16 differed between all compartments but were numerically closer for NEFA and ABD versus NEFA and SUBC. The desaturase indices of the main FA (18:1 cis-9 and 18:0) did not differ between NEFA and ABD. These results support the existence of a different FA composition in ABD compared with SUBC. The greater similarity between the FA profiles of ABD and NEFA compared with SUBC and NEFA and the closer desaturase indices of ABD and NEFA support the hypothesis of a preferential mobilization of ABD fat in dairy cows with LDA.

Milk fatty acids as possible biomarkers to early diagnose elevated concentrations of blood plasma nonesterified fatty acids in dairy cows

“…The major NEFA released are C16:0, C18:0, and C18:1 cis-9 (Hostens et al, 2012), with a further possible conversion of C18:0 to C18:1 cis-9 in the mammary gland through the action of Δ9-desaturase (Leroy et al, 2005). This explains the positive relation in the current study between milk fat C18:1 cis-9 concentrations and blood plasma NEFA concentrations.…”

“…As these NEFA are particularly rich in long-chain FA, such as C18:1 cis-9 and C18:0 (Hostens et al, 2012), concentrations in milk fat of those FA might be linked to severity of NEB. Therefore, the objective of the current study was to assess whether milk FA are potential biomarkers for detrimental levels of blood plasma NEFA.…”

Milk fatty acids as possible biomarkers to diagnose hyperketonemia in early lactation

“…Because these NEFA are particularly rich in long-chain FA such as C18:1 cis-9 and C18:0 (Hostens et al, 2012), elevated concentrations in milk fat of those FA were identified as valuable early warning biomarkers for SCK (Van Haelst et al, 2008). These findings, however, were based on a limited data set.…”

“…This is in accordance with the positive relation between milk fat C18:1 cis-9 and blood plasma NEFA concentration . Indeed, increased concentrations of NEFA in blood plasma result in major changes in FA supply to the mammary gland with C16:0, C18:0, and C18:1 cis-9 being the predominant NEFA released (Hostens et al, 2012), with a further possible conversion of C18:0 to C18:1 cis-9 in the mammary gland through the action of Δ 9 -desaturase (Fievez et al, 2003). Although not in all cases [e.g., Ospina et al (2013) found only 18% of the variability in BHBA concentration to be explained by NEFA during the first 2 wk in lactation], BHBA and NEFA are often linked.…”

Associations between lipid metabolism and fertility in the dairy cow

“…Figure 3 illustrates the concomitant fall in BCS as milk yield increases and circulating NEFA concentrations rise. However, the fatty acid profile of NEFAs in the circulation more closely reflect the abdominal rather than subcutaneous fat stores, suggesting that this is more readily mobilised after calving (Hostens et al 2012). Dry matter intake is the most important determinant of BCS, but the precalving diet and parity also influence the rate and extent of subsequent tissue mobilisation (Hayirli et al 2002;Wathes et al 2007c).…”