Milk fat quality of cows in dependence on feed ration composition
1994
Pazmova, J. | Foltys, V. | Chobotova, E. (Vyskumny Ustav Zivocisnej Vyroby, Nitra (Slovakia))
The influence of feed ration on milk fat quality was studied with five Holstein-Friesian milk cows. Four model feed rations were used: 1. Control, with balanced nutrient content, 2. Surplus of digestible crude protein, 3. Lack of energy, 4. Lack of fiber. Nutritive value of rations is given in Table I. Fat content, concentration of loose fatty acids, acidity, size of fat globules and composition of fatty acids in fat were determined in milk samples. Daily production of milk fat was calculated. Results are given in Tables II-IV. Nutrition did not influence the fat content. However, the fat production per day was significantly highest with feed ration 1 (P less than 0.05). Fat acidity rose significantly with rations 3 and 4. Ration 4 caused an almost double increase (from 0.428 to 0.914 mg KOH g** (-1); P less than 0.01). A similar course was observed in content of loose fatty acids (1.42 l mmol l** (-1) with ration 1, 2.028 mmol l** (-1) with ration 4; P less than 0.05). The control ration produced milk with the smallest fat globules. Lack of fibre created larger fat globules. There were also differences in fatty acid composition. The surplus of digestible crude proteins was attended by the highest content of essential fatty acids (P less than 0.01) and by a slight decrease in concentration in saturated fatty acids. Lack of energy decreased the concentration of C18 acids (P less than 0.01) and unsaturated fatty acids (P less than 0.05). Low fibre content (13 % brought about an increase in acid production to C12 (P less than 0.01), C 13 - C 16 acids (P less than 0.01) and saturated acids (P less than 0.01) at the expense of C 18 acid content (P less than 0.0001) and unsaturated fatty acids (P less than 0.01).
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