Minimize cold stress on newborn dairy calves

CHAZY, N.Y. — Newborn calves are the most susceptible animals to cold stress on a dairy farm.

“Calves less than three weeks of age start to experience cold stress at 59 degrees,” said Sarah Morrison, research scientist at the William H. Miner Agricultural Research Institute. “Once it gets below 59 degrees it becomes more challenging for calves to maintain their body temperature.”

Dairy calves have a low surface-to-mass ratio.

“This means they have a lot more area to lose that body heat relative to an older animal that has a lot more mass and less surface area,” said Morrison during a webinar hosted by Hoard’s Dairyman. “And because they don’t have as much fat or hair they have relatively poor insulation so it’s harder for them to maintain their body temperature.”

Feeding colostrum to calves helps with heat production.

“It has a higher percentage of fat and protein which helps to jump start their metabolic capacity,” Morrison said.

Some of the most susceptible calves to cold stress are born to cows that experienced dystocia.

“If the mom had a hard calving, these calves are more likely to have greater heat loss,” Morrison said. “It is estimated they have a reduced capacity of 36% compared to calves born normally.”

It is important for dairymen to minimize the time between when the calf is born and when they are dry.

“Calves have higher body heat loss when the hair is wet,” Morrison said. “We want to get the hair dry and warm because it doubles the coat depth and helps to provide extra protection.”

One way to warm calves is a warm box.

“A water bath is faster and more efficient at warming calves compared to a warm box,” Morrison said. “I’m not saying give a hot water bath to all your calves, but if you have a calf in need this might be a way to get a calf warm faster.”

Calves have an order of operations for using the nutrients they get from the liquid diet.

“Energy and protein sources go first towards the maintenance requirements of maintaining their body temperature and immune system,” Morrison said. “So, if they have an increased maintenance requirement, they’re going to meet basic needs and there won’t have as much left for growth.”

When the temperature falls from 59 to 32 degrees, Morrison said, the calf requirements for metabolizable energy increases 35%.

“When it gets to 0 degrees, it’s an 82% increase,” she said.

There can be lasting implications for dairy calves that experience cold stress when the cows enter lactation.

A study at Cornell University evaluated calves fed a similar nutrient program during different times of the year.

“When calves are born in temperatures less than the thermal neutral zone they had higher requirements for maintenance which translated into less growth,” Morrison said. “When they entered lactation, they produced less milk during the first lactation so this can have lasting impacts for your herd.”

There are several ways dairymen can increase nutrients to young calves such as providing more milk or milk replacer per feeding.

“Sometimes it’s beneficial to add an additional feeding or you can increase the solids without changing the volume,” Morrison said.

However, Morrison cautions dairymen to be careful about increasing the solids too much.

“You need to provide more water,” Morrison said.

“Consider monitoring the temperature of water at mixing and feeding,” she said. “The milk delivered to a calf should be above her body temperature so an on-demand hot water heater can be very useful in maintaining a consistent supply of water.”

To promote starter intake, Morrison said, for every one part of starter, expect the calf to consume four parts of water.

“If a calf is eating one pound of starter they need to consume at least a half a gallon of water,” she said. “If the water is warm, they will be more likely to drink it.”

The goal for calf housing is to mitigate the effects of cold conditions and to protect calves from thermic stress.

“It also needs to provide adequate ventilation with fresh air,” Morrison said.

“We want to make sure the calves are clean and dry with at least three inches of bedding between the calf and floor,” she said. “You can kneel down on the bedding to see if it’s wet and if the calf needs more bedding.”

Wheat straw is a great bedding for calves, Morrison said.

“It provides an area in which the calves can create a micro climate for themselves,” she said. “They can warm that pocket of air and not lose as much heat to the surrounding area.”

To make sure the calves have enough bedding to be able to nest, Morrison said, dairymen can use a bedding score to evaluate the bedding.

“For a score 1, the legs are entirely visible when the calf is lying; for score 2, the legs are partially visible; and score 3, the legs are generally not visible when lying,” she said.

Bedding is not only important for nesting ability, Morrison said. It has also been linked to the prevalence of respiratory disease.

“This study compared different nesting scores to the prevalence of respiratory disease,” Morrison said. “The general trend shows as we have lower nesting scores, there’s a higher prevalence of respiratory disease.”