Sources of variation in the fatty acid composition of milk fat from monozygous twin cattle housed indoors

Abstract

Some sources of vanauon in milk fat fatty acid composrtions of monozygous twin cattle housed indoors are described. Differences in fatty acid proportions between night and morning mil kings accounted for less than 8% of total observed variation in all acids except butyric; differences between 3 consecutive days for up to 21% of the variance in some acids; and differences between the six cows for up to 46% of the total variance. Significant (P < 0.05) differences between individual members of twin sets were observed in the proportions of most fatty acids.These sources of variation are discussed in relation to the design of short-term twin experiments where fat compositions are determined,

Variation in the characteristics of milkfat from pasture‐fed dairy cows during late spring and the effects of grain supplementation.

“…The observation of variation in the proportions of individual fatty acids in milkfat both betweencow and within-cow (Table 3) supports the data of Chandler & Currie (1972) and Karijord et al (1982). Chandler & Currie (1972) reported large variations in the proportions of the major fatty acids in the milkfat of New Zealand cows fed indoors, even within monozygous twin-sets.…”

“…Chandler & Currie (1972) reported large variations in the proportions of the major fatty acids in the milkfat of New Zealand cows fed indoors, even within monozygous twin-sets. This variation is reflected in total milkfat concentrations, and is likely to be due to differences in the proportions of fatty acids originating from different metabolic pathways.…”

Changes in the composition of milk and rumen contents in cows exposed to a high ambient temperature with controlled feeding

“…On two days of the control period and three days of the treatment period, additional 20 ml samples of milk were taken from each cow at both milkings for subsequent analyses of the fatty acid composition of the milk fat by the methods described by Chandler and Currie (1972).…”

Relationships Between Milk and Milk Fat Composition and Trans-Lactation Changes in Mammary Gland Enzyme Activities in Grazing Cattle

“…Fatty acid compositions were determined by gas-liquid chromatography as described by Chandler and Currie (1972) except that a Varian Aerograph Series 1520 was used for matrix temperature programming. Peak areas were measured by triangulation; compositions were computed on• Ii, weight and molar percentage basis ignoring the• slight differences in molecular weights of the methyl esters and free acids.…”