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Genetic Variation in Milk Minerals

25 September 2009

GLOBAL - Is there an opportunity to produce milk with increased levels of desired minerals?

Human mineral intake varies widely around the world, which results in different countries facing different health challenges. Scientists at the Animal Breeding and Genomics Centre (ABGC), in collaboration with scientists at NIZO food research, have studied the genetic and non-genetic effects on milk concentration of selenium, calcium, potassium, zinc, magnesium and phosphorus.

This information is important for the evaluation of opportunities to produce milk with increased levels of desired minerals. The results have shown that there may be possibilities to change the level of selected minerals in milk through selective breeding, although it appears that farm management would be more effective for selenium.

Morning milk samples of 1,860 Dutch Holstein-Friesian cows from 388 commercial herds in the Netherlands were used for this study. The concentration of minerals was determined by Inductively Coupled Plasma-Atomic Emission Spectrometry. Variance components were estimated using an animal model with covariates for days in milk and age at first calving, fixed effects for season of calving and effect of test or proven bull, and random effects for animal, herd and error.

The intra-herd heritability for selenium was low (0.20), whereas herd explained 65% of the total variation in selenium. The variation between herds most likely results from variation in selenium content in the feed, which partly reflects the variation in selenium levels in the soil. Intra-herd heritabilities for Ca, K, Zn, Mg and P were moderate to high: 0.57, 0.46, 0.41, 0.60 and 0.62, respectively.

For Ca, K, Zn, Mg and P, the proportions of phenotypic variation which could be explained by herd were low (0.13-0.24). In conclusion, this study shows that there are possibilities to alter the mineral composition of milk. For Ca, K, Zn, Mg and P there are good prospects for selective breeding, while for Se, measures at the farm level may be more effective.

An article on this study will be published in the Journal of Dairy Science later this year.

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