Volume 60, Number 593-594, 1980
|Page(s)||140 - 159|
Influence de l'alimentation et de la saison sur les fractions azotées du lait de vacheM. JOURNET and B. REMOND
Laboratoire de la Production Laitière, I.N.R.A., C.R.Z.V. de Theix, St-Genès-Champanelle - 63110 Beaumont (France)
(Reçu pour publication en janvier 1980.)
Abstract - Influence of feeding and season on the nitrogenous fractions in cow's milk
We reviewed the bibliography concerning the feeding and seasonal effects on the concentration of the principal nitrogenous fractions (casein, soluble proteins, non-protein nitrogen) in cow's milk and on their relative proportions.
The differences in the concentration of crude protein (total N X 6.38) between bulk milks are mainly (85 p. 100 on the average) due to differences in the concentration of proteins (table 1).
Variation in the plane of energy nutrition modifies the concentration of crude protein in milk, in the same way; the relative proportion of casein is little affected (fig. 1)
Résumé - Variation in the plane of protein nutrition modifies the non-protein nitrogen content in milk in the same way; this change is essentially due to variation in urea content.
Basal diets have particular effects on the concentration of nitrogenous fractions in milk, but have little influence on relative proportion of casein in the crude protein (table 3).
Season has an effect on the protein content in milk, which is highest when the daylight duration is short, and lowest when the daylight duration is long (fig. 2 - tabl. 5 and 6). The relative proportion of the casein is little affected by season