NEW! Fast Fact: Average Birthweight

Quck answer:  85 pounds

A little more on that: 

By Dr. Noah Litherland, Vita Plus dairy youngstock technical specialist
The best dairy calf and heifer raisers place considerable value on knowing the birthweight of calves.  Birthweight is the starting point for knowing how to manage variation in response to amount of milk fed as well as allowing producers to accurately calculate calf growth.

Weighing calves
Weighing newborn calves is not the easiest task to accomplish on most farms.  First, an investment in a digital platform scale is necessary.  This scale should be dedicated to weighing newborns only.  Weigh newborn calves on a clean platform scale shortly after birth.  Record the weight, ID, time of birth, dam, and date on a data capture form.   Some producers are using RFID to scan calf weight, ID, date, and time directly into DairyComp 305.

A simple, open-platform scale is preferred over a scale used for older calves.  Some producers use an easy-to-clean poly garden cart to wheel calves onto the scale.  Be sure the cart is tared on the scale.  A common source of error is weighing calves after colostrum has been fed (subtract 9 pounds if calves are fed a gallon of colostrum).  Digital scales can be sensitive to moisture; be sure the scale electronics are sealed and kept dry.

Variation
Calf birth bodyweight can vary by as much as 60 pounds in a typical Holstein herd with the average newborn heifer calf weighing 85 pounds.  Sources of birth bodyweight variation include twins, season of calving, calving early, heifer dams, and use of calving ease bulls.  The graph below demonstrates variation in average birth bodyweight in the course of a year on one large Wisconsin dairy.  The average birth bodyweight for the year was 82.9 pounds with calves born in December and January averaging 75.5 pounds (9 percent less).

Average birth bodyweight throughout a year on a Wisconsin dairy farm.

Using the data
Knowing birth bodyweight helps producers dial in their nutrition program to minimize over- or underfeeding calves.  The first two weeks have a huge impact on calf growth.  Overfeeding calves puts calves at risk for nutritional scours and increases the incidence of complications, such as systemic infection and respiratory disease.  Underfeeding calves limits their ability to grow and maintain health.

Targeting a feeding rate of 1.3 to 1.6 percent of bodyweight in milk solids (4 to 5 quarts of milk per day) in the first 10 to 14 days provides calves with adequate nutrition without overfeeding milk.  Having a small calf/big calf program based on birth bodyweight has been successful in decreasing variation in the feeding program. For example, if 85 pounds is the average birth bodyweight, then calves weighing less than 85 pounds are fed 4 quarts per day while calves above 85 pounds are fed 5 to 6 quarts of milk per day.  After day 14, most healthy Holstein calves can handle 6 quarts per day.

Evaluation
Weigh calves at the end of the nursery phase to evaluate nutrition and management in your calf program.  Average daily gain (ADG) is the primary measure used to monitor the nursery program.  Calf growth is a reflection of calf health, nutrition, management and the environment.  Birth bodyweight is subtracted from calf weight at the end of the nursery phase.  The remainder is then divided by the number of days in the nursery phase to calculate ADG (pounds per day).  Aim for at least 1.5 pounds per day through 56 days, with closer to 1.6 pounds per day as the ideal target.