Feeding Focus: Are your youngstock ready for winter?

FEEDING FOCUS December 2016 • Issue 20

Are your youngstock ready for winter?

With winter approaching it is important to keep in mind the impact that cold weather can have on youngstock performance.

Achieving good calf growth rates during prolonged periods of cold weather is challenging as calves will divert energy reserves away from growth to help maintain a comfortable body temperature. If extra feed is not supplied to help compensate for this extra drain on energy, calves will experience poor growth rates and increase their susceptibility to illness or bacterial infection.

Understanding critical temperatures Thermo Neutral Zone (TNZ): The optimum temperature range for calves is typically between 10 and 20°C. At temperatures in this range, the calf will not have to use any additional energy to maintain its body temperature, leaving plenty of energy available for growth.

Lower Critical Temperature (LCT): At 10°C and below, calves will be suffering from cold stress and using increasing amounts of energy to help maintain a constant body temperature.

It’s important to be aware that the LCT for a calf will depend on its age, with calves that are less than three weeks of age having an LCT of 20°C, compared to calves that are over three weeks of age, which have an LCT of 10°C. Upper Critical Temperature (UCT): At temperatures above 20°C, calves will start to suffer from heat stress and have to divert sources of energy in order to keep cool.

LCT

TNZ

UCT

Warm

Cool

Cold Stress

0°C

10°C

20°C

Heat Stress

26°C

Young calves have very limited reserves of energy to help combat the effect of low temperatures and it is therefore essential to minimise the amount of time that calves are exposed to LCTs. Newborn calves are particularly susceptible and, after just 18 hours exposed to low temperatures, will exhaust all of their energy reserves trying to stay warm. This leaves them particularly susceptible to infections and disease.

Cut out the cold It is important to review youngstock housing to limit the impact of temperature on calf health and growth rates.

Calves should always have access to dry, well-bedded housing that has the minimum number of draughts. Air speed within calf housing should be less than 2m/s and humidity levels in excess of 65% need to be avoided.

Calf jackets are a cost effective way to ensure that calves are retaining as much heat as possible and keeping core body temperatures elevated.

Don’t let the cold affect your future calves Due to pressure on feed costs and continuing low milk prices, some producers may have been tempted to reduce, or cut out, feeding heifers with supplementary concentrates, minerals and vitamins. However, coming into winter this approach will - depending on a heifer’s age - have serious implications on productivity and health of future calves.

Pre-bulling heifers: If they have not been fed the appropriate levels of concentrates they are likely to be underweight and not ready to serve. If heifers are served on age rather than weight, conception rates will be low and those that do conceive are likely to calve down too light or small. This will have a negative impact on calf ability and their own ability to compete in the rest of the herd.

Pre-calving heifers: Without the appropriate feed supplementation they are likely to be in poor condition, lacking in essential minerals and vitamins and be too light to successfully calve down. Poorly conditioned heifers that do successfully calve will produce low quality colostrum, as well as give birth to calves lacking in size and with poor internal development.

In order to ensure heifers are in the best condition for calving over winter, make sure they are provided with a good pre-calving diet six weeks prior to expected calving.

© ForFarmers 2016. All rights reserved

Combat the cold with extra feed In order to maintain strong calf performance during cold weather it is important to provide calves with extra feed to help their bodies compensate for exposure to LCTs. If calves are not provided with additional feed, they risk straying into a negative energy balance, where the amount of energy a calf is expending to keep warm and survive is greater than the amount of energy they are obtaining from feed.

Feeding additional calf milk replacer (CMR) is essential to ensure calves are able to keep themselves warm but also have the energy reserves to maintain strong levels of growth.

Failure to do so can negatively impact on weight gains, as well as damaging a calf’s immune system, leaving them susceptible to illness.

A good rule of thumb is an extra 10 grams of CMR for every one degree drop below the LCT. Another important point is to try to increase the CMR feeding rate by changing the concentration, i.e. 15% to 17%, rather than increasing litres fed per day.

Additional CMR Required (g/day) Ambient Temperature

Calf aged < 3 weeks (50kg)

Calf aged > 3 weeks (65kg)

20OC

0

0

10OC

107

0

5C

161

66

201

131

322

262

O

0OC -10 C O

For more information on caring for your calves this winter, please contact your ForFarmers Account Manager, or ask to speak to one of our Regional Youngstock Specialists.

www.forfarmers.co.uk