Feeding for growth
There are many systems being promoted from the huge milk volume Ad Libitum systems to the low volume, highly concentrated systems.
Whatever system you choose it is important the calf’s needs are meet. She needs enough energy to grow, to keep warm in cold weather or cool in warm weather and of course to develop from a pre-ruminant to a ruminant.
There are 3 phases in the development of a calf’s' digestive system.
Liquid feeding phase: All nutrients are obtained from milk or milk replacer for about the first 3 weeks.
Transition Phase: Milk and starter rations contribute to meeting nutrient requirements. After 3 weeks the rumen will be developed enough for the ration to be contributing to the energy required for growth, but it will not be developed enough to digest pasture or hay. Calves can be weaned when they consuming 800gm to 1kg of starter ration per day.
Ruminant Phase: Nutrients are derived from solid feeds through microbial fermentation in the rumen. By the time the calf is 12 weeks old the rumen will be functional enough for her to develop on pasture, forage or grains.
Breaking these phases down into a weekly feeding plan makes life a lot simpler!
All her energy and nutrition comes from colostrum or milk.
Because she cannot fully digest starter ration during the first few weeks, it is important to feed enough milk to meet all energy needs.
At this stage it is important to introduce starter ration because the enzymes will start rumen development.
Now the rumen is starting to develop. Small amounts of energy are taken from starter ration, but the majority of energy is from milk.
By the end of the week six (42 days) the rumen should be developed enough for milk to be reduced but only if the calf is eating 700 grams of starter ration per day. If the calf is eating 700 grams of starter ration the milk volume can be reduced to 4 litres fed once per day, ideally late in the day. If the calf is not eating 700 grams of starter ration per day, it should be kept on a high milk diet until she is eating enough.
By now the rumen will be developed enough for the calf to continue to grow on pasture or pasture based feeds and grain.
So how much milk to feed?!
If we look at the units of energy a calf needs and how much energy is in the feed then we can make a good programme. The units of energy are called MJME. Translated MJME is Mega Joules of Metabolisable Energy.
A 40kg calf requires
6.8 MJME per day for maintenance in fair conditions.
11.4 MJME to gain 1 kg of live weight.
For example, for a 40kg calf to gain 0.8kg per day she requires a minimum of 15.9 MJME (6.8 for maintenance plus 80%of 11.4 MJME to gain .8kg). This equates to 5.3 litres of whole milk.
Available MJME (approximate) per product. MJME is Mega Joules of Metabolisable Energy.
Whole milk: 3 MJME/Litre
Colostrum: 3.4 MJME/Litre
Milk Replacer: 21.9 MJME/kg
Starter ration: 11-13 MJME/kg DM
This can all look a bit complicated so we have worked out the MJME required for the weight and where she should be each week until weaning for both whole milk and milk replacer.
Start by using a weight tape every week to measure the growth and adjust feeding volumes using the chart example below. Wrap the tape around the calf just behind the wither and elbow.
Whole Milk example
IMPORTANT! In cold weather increase volumes by 2% for every degree under 5°C .
EXAMPLE: Daily Volume: 5 L
At 4°C increase 2% = 5.1 L
At 0°C increase 10% = 5.5 L
At -5°C increase 20% = 6.0 L
At -10°C increase 30% = 6.5 L
The CMR rate is a guide only. Always look at the manufacturers recommendations and mix 150 grams per litre of water.
TOP TIP! Weaning
To prevent weight loss at weaning it is important the calf has had ad lib grain from Week 1.
At 42 days the calf should be consuming 700gms of starter ration. Once this happens calves can have milk reduced and be fed once a day. Do not go to once a day feeding under 42 days.
Ideally calves on once a day milk feeding should be fed in the evening. The calf will then sleep on a full stomach but will be hungry during the day. With ad lib grain available they will consume more to accelerate rumen development. Providing the calf is consuming a minimum of 1kg of grain she can be weaned from 8 weeks. Ideally you would wean when she is double the birth weight.