Milk and colostrum of Quarter horse mares examined by researchers

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The colostrum of purebred Quarter horse mares has a higher protein content and reduced lactose when compared to other breeds, researchers report.
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The colostrum of purebred Quarter horse mares has a higher protein content and reduced lactose when compared to other breeds, researchers report.

Ícaro Barreto and his colleagues in Brazil set out to characterize the chemical composition and lipid profile of the colostrum and milk of Quarter horses.

Thirty-four purebred mares were selected for the study, separated into groups according to age, birth order, and lactation stage.

Colostrum samples were collected in the first six hours after delivery and milk samples from the 7th day after birth, and then at intervals of 14 days until the end of lactation.

“The values obtained in the colostrum composition confirm its nutritional richness,” the study team reported in the open-access journal PLOS ONE.

The protein level in the colostrum averaged 18%, which was higher than the average of 15% reported by others in Hungarian Draught, Haflinger, Breton and Boulonnaise mares; and the 16% found in another study involving Arabian mares.

The lactose content of the Quarter horse colostrum was 1.53%, considerably lower than studies involving other breeds which showed levels of 2.95% and 2.46%.

“The results suggest that the colostrum of Quarter Horse mares may contain more protein and be less dense in energy when compared to other breeds,” they wrote.

However, the high fat content of the colostrum stands out, being 2.7 times greater than the milk fat in the initial third of lactation.

When analyzing the milk, a reversal between the protein and lactose concentrations was noticeable.

“However, as the lactose concentrations in milk are not as high as the protein concentration in colostrum, the levels of total solids and defatted dry milk extract are considerably lower than those observed for colostrum.”

Other studies put total milk proteins in Quarter horse mares at 1.8% to 2.9%, which are close to the values found in the current study, and fell within the range reported in other studies involving various horse breeds.

The fat content in milk found by the researchers was lower than the range of 1.0% to 1.5% reported by others in another Quarter horse study, and also below the average value of 1.25% reported in another study. However, it was higher than the 0.62% reported by researchers for milk from Mangalarga mares.

The researches found that milk composition was not influenced by the mares’ age, but there was a significant effect of the lactation stage on the fat, total protein and casein levels.

“There is variation in the lipid composition of milk according to the lactation stage, without changing the characteristic profile of the mares’ milk or diminishing the nutritional quality of the lipid fraction,” they wrote.

The study team comprised Barreto, Stela Urbano, Cláudia Macêdo, Luiz Borba, Bruna Chags and Adriano Rangel, all with the Federal University of Rio Grande do Norte in Natal, Brazil; and Chiara Oliveira, with the Federal University of Bahia in Salvador, Brazil.

Barreto ÍMLG, Urbano SA, Oliveira CAA, Macêdo CS, Borba LHF, Chags BME, et al. (2020) Chemical composition and lipid profile of mare colostrum and milk of the quarter horse breed. PLoS ONE 15(9): e0238921. https://doi.org/10.1371/journal.pone.0238921

The study, published under a Creative Commons License, can be read here.

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