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Fatty acid composition of Alpine goat milk and Domiati cheese with pasture feeding during a whole lactation

K. A. Soryal, S. S. Zeng, K. Tesfai, and T. Sahlu

E (Kika) de la Garza American Institute for Goat Research, Langston University, Langston, OK

Forty-four lactating Alpine goats were randomly allocated into four groups in an experiment to investigate the effect of pasture feeding with different levels of concentrates on milk and cheese fatty acid composition during the different stages of lactation. Group A was confined and fed alfalfa hay supplemented with 0.66 kg of concentrate mixture per kg of milk over 1.5 kg/d. Groups B, C, and D were rotationally grazed and received 0.66, 0.33, and 0 kg of concentrate mixture per kg of milk over 1.5 kg/d, respectively. Bulk tank milk samples for studying milk fatty acid composition and for processing into Domiati cheese were collected from each group twice monthly for a 6-month lactation period (April to September, 2001). Cheeses were sampled fresh and at 1 and 2 months of pickling in whey. Milk and cheese fats were extracted and fatty acids were analyzed. Caprilic and capric acids represented 12.7 and 14.2% of milk and cheese total fatty acids, respectively, while lauric acid was 4.3 and 4.1% and myristic acid was 11.3 and 12.0% of milk and cheese total fatty acids, respectively. Palmitic acid was highest in concentration among total fatty acids of both milk and cheese (30.2 and 30.2%, respectively), while oleic acid (23.9 and 22.1% of total fatty acids, respectively) was highest among total unsaturated fatty acids (27.8% and 26.4%, respectively), representing 85.8 and 83.9% of total unsaturated fatty acids in milk and cheese, respectively. Pasture feeding (Group D) significantly decreased caprilic, capric, and lauric acids while concentrate feeding increased concentrations of these acids in milk fat. Concentrate feeding significantly increased levels of these fatty acids in cheese fat, while pasture feeding significantly decreased their concentrations. Pasture feeding reduced saturated fatty acid concentrations in cheese. Caproic, caprilic, and capric acid levels in cheese were significantly higher in mid-lactation, while lauric and palmitic acids tended to be higher in late lactation. In conclusion, pasture feeding reduced levels of some saturated fatty acids in milk and cheese, particularly lauric, myristic, and palmitic acids, which are considered to be cholesterol-raising in human nutrition.


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