Introduction to the New Nutrition Requirements for Feeding Calves
By Dr. Jim Quigley, Calf and Heifer Technical Lead, Cargill
The National Academies of Science Engineering and Medicine (NASEM), previously known as the NRC (National Research Council), has updated the nutrition requirements for dairy cattle that replaces their 2001 standards. These new requirements reflect research from the last 20 years and include significant updates for feeding calves.
During a calf’s early life, from birth to 2 months, growth tends to be lower because their immature digestive system. Between 2-4 months a calf’s dry feed intake increases, allowing for quicker and more economic gain. This means that when setting average daily gain (ADG) targets, we should consider that calves may grow more slowly in the first two months of life.
Equation to Predict Dry Feed Intake
This equation is a major improvement from the 2001 edition which did not provide any prediction of dry feed consumption. NASEM developed two dry matter intake equations for calf raising in either temperate or sub-tropical climates. The equation allows us to predict when calves will begin eating calf starter and changes over time.
Energy is the Primary Driver of Growth
The NASEM model for estimating calf growth is based on metabolizable energy (ME) requirements and metabolizable protein (MP) requirements. Metabolizable energy or ME encompasses the calf’s energy requirements for both maintenance and gain. Calves will first expend energy for maintenance such as metabolic processes like breathing, immune system function, digestion, and regulating body temperature. After maintenance requirements are met, calves will use available energy to metabolize protein for growth. Balancing energy to protein is critical when meeting protein needs for growth. The ratio of MP:ME is a key metric for formulating rations for young calves.
Putting into Practice
Evaluate your program—What is your current ADG from birth to 2 months? Birth to 4 months? Calves that get sick, are stressed, are exposed to heat or cold stress are less likely to achieve your goals. And implementing a feeding program to meet an aggressive goal say—2 pounds per day—will not be successful unless you lessen these roadblocks. Also note, the new NASEM supplies recommendations for calves at one point in time, at a given body weight, target ADG, and environment. While this approach is useful for evaluating an average diet, I recommend using models to evaluate programs over time to decide whether a program will meet your goals for growth, costs, and realistic changes. Work with your nutritionist to implement the best feeding program based on your farm’s goals.
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