Understanding the basic concepts of growth helps improve calf and heifer management.

Early postnatal growth is the most efficient time to develop skeletal growth, muscle growth, deposit protein and attain the highest feed efficiency.

Mammary development can be enhanced by liquid (milk) feed intake prior to weaning. Calf raisers are advised to assess and adapt their feeding practices to ensure adequate growth while maximizing economic benefits.

Winter feeding in cold climatic conditions requires additional attention to ensure the young calf has been provided with sufficient nutrients for maintenance and for growth expectations.

The young calf has limited reserves of energy when exposed to temperatures below the lower critical temperature (see Table 1) for extended periods of time. These reserves are quickly depleted in approximately 18 hours for the newborn calf.

Research, under controlled dry conditions with adequate bedding, indicates that calves housed at -4ºC (24.8ºF) require approximately 30 percent more calories for maintenance.

This number will increase as temperature goes down, humidity rises and calves are subject to wet bedding.

Adding extra bedding, straw in particular, will help raise the ambient temperature of the calf.

On average, when the calf can fully nest in the straw, her surrounding temperature will rise by 4ºC.

When a calf falls under negative energy balance, immune status can be easily compromised and the calf becomes susceptible to bacterial and viral infections.

To maintain the same amount of gain in colder environments, increase the amount of powder fed to calves on average by 7.7 grams per °C below their critical temperature. (See Table 2)

Fat and its source are important in milk replacers for young calves to ensure a high absorption and to best meet their energy needs, especially in cold-stress conditions.

Young animals require highly digestible fats and oils, with a correct fatty acid profile and saturation structure to provide a profile similar to milk fat.

This will help to maximize growth potential and avoid “fatty feces.” Drackley found that protein requirement is a function of the energy allowable gain.

Correct mixing of the milk replacer and temperature of water used will provide a more uniform blend and low-fat particle size (<1.5 microns). These factors encourage optimum absorption capacity by the young calf.

Effect of concentrate feeding
Calves utilize energy less efficiently from starter feeds than milk replacer because carbohydrate and protein in the starter must be fermented in the developing rumen prior to digestion by the calf.

Feeding more of an appropriately balanced milk replacer diet to meet requirements for both energy and protein allowable gain appears to be the most systematic solution to cold-stress challenge.

Feeding more starter will not help the young calf maintain a steady rate of gain during cold weather conditions.

Ways to help the young calf under conditions of cold stress:

• Ensure the calf has access to dry, well-bedded shelter that provides protection from wind and is free from drafts.

• Provide extra energy through its feed by increasing the amount of milk replacer being fed. (See Table 3.)

• Observe the weather forecast so that changes can be introduced gradually, avoiding stomach upset (bloating).

Feeding extra milk replacer powder:

• The extra amount can and should be split into two or more meals.

• It can be added on top of a milk meal.  PD

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PHOTO:
TOP RIGHT: Young animals require highly digestible fats and oils, with a correct fatty acid profile and saturation structure to provide a profile similar to milk fat. Photo by PD staff.