Failure to Thrive: Cachexia and Weak Calf Syndrome

John Maas

In calves, the weak calf syndrome has been reproduced by feeding low-protein diets to prepartum cows that subsequently calved in environments in which the temperature was well below the thermoneutral zone for calves.⁷⁸³ The dietary recom­mendation for crude protein intake for third-trimester pregnant cows and heifers is 0.9 kg (2 lb) of total crude protein per day.

Cows weighing 450 kg (1000 lb) therefore need to consume 9.9 kg (20 lb) dry matter of good- to excellent-quality hay that is 10% or more crude protein. A quadratic equation has been developed to predict crude protein (CP) intake of the dams if their serum total proteins, urea nitrogen, and creatinine are known.⁷⁸⁴ This equation predicts the daily crude protein intake on a continuing basis.

Daily CP consumption (kg) = 0.1806 + 0.04327 (BUN) - 0.3 3497 (creat) + 0.06963 (TP) - 0.00025 (BUN)² + 0.06049 (creat)² - 0.00666 (bUn ? creat)

where BUN is blood urea nitrogen (mg/dL), creat is serum creatinine (mg/dL), and TP is serum total protein (g/dL).

Also, the use of this formula could predict CP intake for pregnant heifers and pregnant cows. This relationship may prove to have important clinical applications when weak calf syndrome or protein-calorie malnutrition is suspected and the gestation diet of the dams is not available for analysis (as under some range conditions). Supplements such as molasses licks that contain urea may tend to overestimate CP intake.⁷⁸⁵