At zero degrees, a 90-pound calf eating one pound of powder or solids daily (equal to one gallon of 12.5 percent solution) can “burn up” its entire body fat reserve (about 3 to 4 percent of body weight) within 18 hours. Bring on the groceries!
Calves’ energy intake is the sum of the starter and milk/milk replacer consumed. So you might ask, “can’t the calves just eat more starter to compensate?” Yes, they can, if they’re ruminating and if they’re eating one to two pounds of grain per day. But most calves less than two weeks old are not. Milk or milk replacer is often the sole source of energy for pre-ruminating calves, and a significant source for the remainder of energy needed by ruminating calves.
What’s cold to a calf?
A newborn calf’s thermo-neutral temperature is about 50 to 80 degrees. By a month old, a calf’s lower critical temperature is more like 32 degrees. Depending on a number of factors, newborn calves are neither heating nor cooling themselves somewhere between 50 and 80 degrees. Some of these variables are:
- Wind exposure
- Hair coat condition (wet, rain, snow, mud, manure)
- Thickness of hair (adaptation)
- Bedding type and condition
Calves may need one-third more energy when temperatures drop from 55 degrees to 25 degrees. Realize, though, that the extra energy required is not used or available for growth or support of a developing immune system – the extra energy is diverted from weight gain and growth to maintenance of core body temperature. Some researchers estimate that 20 percent more energy yet is required for immune system development.
On an as-fed basis, a typical all-milk protein milk replacer will contain:
- 1.87 Mcal ME/lb for a 10 percent fat milk replacer
- 2.08 Mcal ME/lb for a 20 percent fat milk replacer
Why not double for a 20 percent fat product versus a 10 percent fat product? The difference is the energy displacement of fat versus lactose.
What are the ways to maximize or increase energy intake during times of cold weather?
- Feed a 20 percent fat milk replacer
- Increase liquid feeding rate by 25 to 50 percent, or
- Give an extra pint a.m. and p.m., or
- Feed an extra half bottle at noon to calves less than three weeks of age, or
- If limited by bottle size to a specific liquid amount, increase the milk replacer powder dilution rate to 25 to 50 percent higher mixing rate, and then feed normal amount of liquid, but do not exceed 20 percent solids, and keep water available.
- Keep liquid water available if at all possible – calves consume considerably more starter when water is available
- Don’t forget the “warm soup effect” – warm fluid feeding can warm moderately chilled calves
What about supplementing extra fat?
Fat supplements add energy, but feeding over 0.25 pounds of fat supplement per day often results in reduced starter intake – counterproductive!
Calves will take off muscle as well as fat if they are below their maintenance energy requirements. This can be caused by temperature alone, but is exacerbated by the environmental factors listed above, plus:
- Reduced feed intake
- Disease challenge
- Weaning stress
Research has shown that calves will maintain health and acceptable weight gain with a 50 percent higher milk replacer feeding rate during cold weather.
This article was originally printed in FrontLine by Milk Products, LLC.