Holstein, Jersey and its cross affects fatty acid composition under grazing conditions.

PALLADINO, R.A., BUCKLEY, F., MURPHY, J.J., PRENDIVILLE, R., AND KENNY, D.A.

Montreal

Congreso; . 2009 Joint ADSA-CSAS-ASAS Annual Meeting.; 2009

ADSA-CSAS-ASAS

Dietary n-3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acid (CLA) have beneficial properties for human health. Dairy cow breed affects PUFA concentration in milk but most work to-date has been conducted under TMR based systems. Additionally, there is little information about the cow breed and heterosis on concentrations of milk PUFA. The objective of this study was to compare milk FA concentration of two dairy cow breeds (Holstein and Jersey) and their F1 hybrid managed under a grazing system. Eighty-one spring-calving dairy cows (27 cows per treatment) were managed under a predominantly perennial ryegrass pasture during two experimental periods (June and July). Milk yield, fat, protein, lactose and fatty acids (FA) were recorded once a week during each period. Milk FA were analyzed by gas chromatography. Data were analyzed by ANOVA. Cow was used as random effect. Statistical model was Yij= μ + breedi + period j + breedi x periodj + errorij. No interaction was found for any of the variables studied over the two periods. Holstein cows had the highest milk yield, Jersey the lowest with the crossbred animals intermediate (P<0.01). Milk fat and protein were highest for Jersey, lowest for Holstein and the crossbred animals intermediate (P<0.01). Holstein had higher n3:n6 ratio (P<0.05), C18:2 n6, and the ∆9 desaturase index (P<0.01). Milk CLA also tended to be higher in Holstein (Table 1). Under the grazing conditions employed here, Holstein dairy cows produced more milk with a higher content of CLA, probably due to the higher mammary gland ∆9 desaturase enzyme activity observed. No evidence for any heterotic effects on milk related variables measured was found from this study.