Metabolizable Energy and Absorbed Protein Requirements for Milk Component Production

• Published in: Journal of dairy science Vol. 76; no. 6; pp. 1575 - 1588
• Main Authors: Dado, R.G., Mertens, D.R., Shook, G.E.
• Format: Journal Article
• Language: English
• Published: Savoy, IL Elsevier Inc 01.06.1993; Am Dairy Sci Assoc; American Dairy Science Association
• Subjects: absorbed protein; absorcion; Absorption; acide amine; acide gras; acidos grasos; Adenosine Triphosphate - metabolism; amino acids; Amino Acids - metabolism; aminoacidos; Animals; besoin nutritionnel; Biological and medical sciences; Cattle - physiology; dairy cows; Dietary Proteins - metabolism; Energy Metabolism; fatty acids; Fatty Acids - biosynthesis; Female; Food industries; Fundamental and applied biological sciences. Psychology; gliconeogenesis; Gluconeogenesis; glucosa; glucose; glyconeogenesis; grasa de la leche; lactacion; Lactation; Lactose - biosynthesis; Lipids - biosynthesis; matiere grasse du lait; metabolisme energetique; metabolismo energetico; metabolizable energy; Milk and cheese industries. Ice creams; milk components; milk fat; milk protein; Milk Proteins - biosynthesis; necesidades de nutrientes; neoglycogenese; nutrient requirements; nutritional requirements; proteinas; proteinas de la leche; proteine; proteine du lait; proteins; Triglycerides - biosynthesis; vacas lecheras; vache laitiere; metabolizable energy; LN; absorbed protein; nutrient requirements; ME; TCBA; AN; milk components; AP; Proteins; Vertebrata; Mammalia; Bovine; Energy; Nutrition; Production; Artiodactyla; Metabolism; Ungulata; Milk
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(93)77491-3

Metabolic pathways of milk component synthesis were used to estimate metabolizable energy and absorbed protein requirements for lactation. Amounts of ATP and AA used for synthesis of each component from absorbed substrates were determined. Coefficients were adjusted to account for additional inefficiencies and to define requirements in terms of dietary supply based on NRC energy requirements and N balance data. Assuming that 10% of glucose required was derived from AA, metabolizable energy and absorbed protein requirements were 6.02 Mcal and .136 kg/kg of lactose, 13.43 Mcal and .127 kg/kg of fat, and 7.57 Mcal and 1.069 kg/kg of protein, respectively; an additional .144 Mcal/kg of milk was required for milk volume. For production of milk containing 4.8% lactose, 3.5% fat, and 3.3% protein, absorbed protein required for lactose and fat may account for 14.1 and 9.6%, respectively, of total absorbed protein required for milk production. Efficiency of protein utilization for milk protein synthesis may be as high as 90% when 10% of glucose requirements must be supplied by AA. Expressing nutrient requirements for lactation on a component basis enables calculation of requirements for milk production of any composition and does not rely on correlations between major milk components.