Milk value could be increased on-farm by supplying milk with enhanced concentrations of minor compounds that have bioactive properties. Compounds of interest in this study were the whey proteins lactoferrin (Lf) and lactoperioxidase (LP), and milk fatty acids; particularly conjugated linoleic acid (CLA) and omega-3 fatty acids. Mixed genotype cows (20 Friesian, 20 Jersey and 20 crossbred) were sampled to determine the effect of cow genotype and age on Lf concentration, Lf yield and LP activity at 4 times during the season. In milk fat, concentration of CLA and omega-3 fatty acids were determined twice during the season. Cow genotype had no effect on Lf concentration but age did (P < 0.002), with 4-year and older cows producing greater concentrations in milk than 3 year old cows. For harvesting Lf, Friesian cows would be the most profitable, with the greatest Lf yields, particularly in mid-late lactation. The highest LP activity levels throughout lactation were demonstrated in Jersey milk. In milk fat, Friesian cows produced milk of a putatively healthier profile, with greater concentrations of unsaturated fatty acids, CLA and omega-3 fatty acids. Key words: milk value; cow genotype; lactoferrin; lactoperoxidase; conjugated linoleic acid; omega-3 fatty acids.
Proceedings of the New Zealand Society of Animal Production, Volume 65, Christchurch, 53-58, 2005
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