Predicting Requirements for Growth, Maturity, and Body Reserves in Dairy Cattle

• Published in: Journal of dairy science Vol. 82; no. 9; pp. 1968 - 1977
• Main Authors: Fox, D.G., Van Amburgh, M.E., Tylutki, T.P.
• Format: Journal Article
• Language: English
• Published: Savoy, IL Elsevier Inc 01.09.1999; Am Dairy Sci Assoc; American Dairy Science Association
• Subjects: Animal Nutritional Physiological Phenomena; Animal productions; Animals; Biological and medical sciences; Body Composition; body condition; Body Weight; Cattle - growth & development; Cattle - physiology; dairy cows; Dietary Proteins - administration & dosage; energy cost of maintenance; energy cost of production; Energy Intake; Energy Metabolism; energy requirements; energy retention; equations; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; growth curve; heifer growth; heifers; Intermediate and energetic metabolism; Lactation; lactation number; Metabolisms and neurohumoral controls; Models, Biological; Nutritional Requirements; Pregnancy; protein requirements; Terrestrial animal productions; Vertebrates; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Weight Gain; energy requirements; heifer growth; protein requirements; Operations research; Optimal growth; Energetic value; Farming animal; Lactation; Nutritive value; Dairy cattle; Ox; Forecast model; Optimization; Milk production; Nutrient requirement; Vertebrata; Mammalia; Energy requirement; Protein values; Heifer; Artiodactyla; Ungulata; Net energy analysis; Metabolic storage
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(99)75433-0

The 1996 National Research Council Nutrient Requirements of Beef Cattle equations used to compute growth requirements, target weights, and energy reserves were modified and evaluated for use with dairy cattle. Coefficients used to compute target weights during growth and equations used to predict body weights (BW) for each condition score in computing energy reserves were modified. Equations used to compute net energy and protein requirements for growth were evaluated with data from studies of body composition changes in Holstein heifers; this model accounted for 96% of the variation in energy retained with a 4% bias. Coefficients used to compute target growth rates and BW were evaluated with data from Holstein heifer growth studies. Actual and target shrunk weight gain and BW values were before first pregnancy, 0.82 versus 0.87kg/d with a 370-kg weight at first pregnancy versus a target of 352kg; during the first pregnancy, 0.63 versus 0.69kg/d with a weight at post first calving of 533 versus 545kg; and first lactation, 0.136 versus 0.104kg/d with a second post-calving weight of 592kg versus 590kg. The equations used to predict body reserves from BW and condition score were evaluated with data from a study of body composition associated with body condition score in Holstein cows; the revised model accounted for 96% of the variation in body fat and predicted 80kg shrunk BW change per body condition score compared to 85kg observed.