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Extension > Agriculture > Dairy Extension > Calves and heifers > Caring for calves in cold climatic conditions

Caring for calves in cold climatic conditions

Neil Broadwater

Published in Dairy Star November 19, 2010

“A calf can stand a good deal of cold weather if it is dry and protected from drafts.” This quote is taken from the Agricultural Experiment Station Circular, July 1931, Kansas State College of Agriculture (today's Kansas State University). Advice from over 79 years ago that is still pertinent to calf raisers today.

Minnesota calf raisers know there are many challenges in raising calves during the winter months. Let's review some 'calf facts' to remember for the colder temperatures ahead. Normal body temperature for calves is 101.5° F. The thermoneutral zone (TNZ) is 50 to 68° F. This is when the amount of heat produced is in balance with the amount of heat lost (see Figure 1). Below the 50° F lower critical temperature (LCT), newborn calves need extra energy or they will begin to burn body tissue and lose weight causing the immune system to be depressed. Research shows cold stress also decreases the rate of absorption of colostrum in newborn calves. The LCT is also dependent on wind, humidity (optimal is 65 to 75%), hair coat (greater insulation if dry rather than wet and matted), sunlight, bedding, rumination, age and size of calves. As a guideline, maintenance energy requirements increase 1% for each 1° F drop below the LCT. As calves begin eating calf starter, rumen fermentation is created, producing body heat and reducing the LCT. Also as body weight and age increases, the LCT decreases.

There are two critical management issues that should never be overlooked during Minnesota's cold winters. They are housing and nutrition.

Housing management

Good nutrition and other management practices cannot overcome poor environmental conditions and large pathogen loads where calves are housed. Some key housing management issues include:

Nutrition management

Additional energy is the key to winter feeding of calves. Research shows that when calves receive adequate nutrition, they can tolerate considerable periods of cold without affecting growth. Maintenance energy requirement increases as temperature incrementally decreases. As an example, if using a 20:20 CP:fat milk replacer (MR), Table 1 (Mills and Van Amburgh, Cornell University) shows it takes 1.1 pounds just for maintenance for a 100-pound calf at 50° F. At 5° F, the amount jumps to 1.7 pounds. At -15° F, the requirement is 1.9 pounds or 73% more compared to 50° F conditions. The table simply confirms that diet adjustments must be made to meet the calf's maintenance and growth requirements as temperatures decrease below the LCT.

Additional energy can come from higher milk or milk replacer amounts, increased fat intakes, and/or increased starter intakes. Calves over 3 weeks of age that are voluntarily eating more starter have a lower LCT, which helps cover their increased energy needs. For example, an additional 0.6 pound of a typical 18% protein calf starter will meet increased maintenance needs to 20° F. An extra 1.0 pound meets additional energy needs down to 0° F, and eating 1.4 pounds more will provide enough energy at -20° F. The sooner calves start eating grain, the more benefit they will get in terms of generating heat.

Milk replacer or whole milk should be warmed to 105° F before feeding so the calf does not have to expend extra energy to bring the milk up to body temperature after ingestion. In addition, offer clean, lukewarm (63 to 82°F) drinking water 2 to 3 times a day to encourage feed consumption and to counteract the effects of cold stress.

The goals in raising calves should be the same year around – healthy and vigorous calves, doubling their birth weight by 56 to 60 days of age with 4 inches of frame growth. Increased attention to housing and nutrition management practices for calves during the colder months of the year will help minimize calf illness and maximize daily growth to ensure they will be viable replacements and ready to come into the milking string on time.

Table 1. Pounds of 20% protein, 20% fat MR required per day to meet maintenance requirements of calves at varying temperatures.

Body wt,
Lb

Temperature, °F

68

60

50

32

15

5

-5

-15

-20

60

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

80

0.8

0.8

0.9

1.1

1.3

1.4

1.5

1.6

1.7

100

1.0

1.0

1.1

1.3

1.6

1.7

1.8

1.9

2.0

120

1.1

1.1

1.3

1.5

1.7

1.9

2.0

2.1

2.3

140

1.2

1.2

1.4

1.7

2.0

2.1

2.3

2.4

2.5

Based on 2001 NRC Requirements. Whole milk is approximately 12.5% solids and contains approximately 18% more energy than average milk replacer. Therefore, adjust table values for whole milk.

Source: Northeast DairyBusiness - PRO-DAIRY, Dec. 2005 (Mills and Van Amburgh, Cornell University).

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