Making the most of heifer growth rates

Feed conversion efficiency (FCE) is optimum in young animals – that’s a fact.

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Heifer replacement FCE is highest in the first eight weeks of life after which it rapidly tails off – check out the graph.

In the first two weeks, 100g of feed will give approximately 50 – 60g of growth, after which it dramatically falls during the first 12 months of life, by when 100g feed will only give approximately 9g of growth.

Heifer feed efficiency

Heifer growth rates

* (Average daily gain) / (dry matter intake) x100

Source: IRTA

Feeding for growth has also proved to be cost effective according to research findings from the Institute of Research and Technology in Agrifood (IRTA). To achieve average age at first calving at 23 months and a body weight of 650kg, feeding a total six litres of milk per day to weaning at two months resulted in the lowest total rearing feed costs.

The data in the following table confirms that heifers fed four litres during the same period had some catching up to do later on when FCE is lower. In other words it is cheaper to put weight on heifers earlier.

Milk volume fed and the impact on total heifer rearing costs
(calving 23 months, 650kg body weight)

ffg graph

 Three reasons why FCE is the highest in early life

1. Milk is more digestible and nutritious than concentrate to a young calf

2. Calves fed concentrate utilise the ME that they consume less efficiently than the energy derived from milk or calf milk replacer. This is because at least some of the carbohydrate and protein in starter feed must be fermented in the rumen prior to being digested by the calf. As rumen activity increases, the amount of heat produced by the animal also increases which can be considered a loss as it cannot be utilised by the animal

3. Before puberty, growth is mainly bone and muscle, after which heifers gain more fat relative to bone and muscle, consequently they are less feed efficient.

FCE is not the only high point during pre weaning.

a. This phase is extremely important for the development of stomach, organ and mammary cells which together with metabolic programming are set on particular trajectories during this period of the calf’s life.

b. Improved early nutrition and growth rates are also correlated with increased plasma IGF-1, a hormone associated with higher growth rates which help to support increased disease resistance, improved immune response and in turn, reduced mortality.

Finally, two external factors determine FCE

Feed: ingredients can impact, as does quantity; refer back to the above table.
Environment: environmental stress can have an adverse impact on FCE.

To find out more download our Farmers Guide to Feed Conversion Efficiency.

Attention to detail: Part 2

Unlocking potential in the milk drinking phase

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This week we’re introducing four more fundamentals that will help you to unlock your heifer calves’ potential. Small management details like these can contribute towards their growth and the animals’ ability to hit required growth targets for 24 month calving.

Fact, if you increase your heifer calves’ daily liveweight gain from 500g to 800g in the milk
drinking phase, then they’ll have the potential to increase yield by an average 450 litres in the first lactation*.

1. Drinking angle

The strength of the oesophageal grove reflex is triggered by sucking, milk temperature and the position of the head. Consequently, calves need to drink from shoulder height to ensure neck extension, a weak groove reflex can cause milk to enter the rumen which can lead to problems such as bloat and scours. If you bucket feed, then raise the buckets to sit at least 30cm from the floor.

Drinking-Angle_v2-TW

 

2. Consistency

Whatever you do – from the time of feeding to volume, concentration and
temperature of milk, dry feed and access to straw – be consistent. It’s vital to sustain intakes and growth.

3. Maintaining and cleaning feeding equipment

Check teats regularly – splits and wear and tear could lead to fast drinking and in turn, abomasal overflow and scour which could impact on growth. Check again to make sure the teats are set up right – the hole should be in a + position, not an x position, otherwise milk flow will be compromised.

Teat-Position-TW

4. Ambient temperature

Your calves have a thermal neutral zone of 15oC to 20oC, below which they will need more energy for maintenance and keeping warm. If this energy is not supplied, then growth rates and immunity could be compromised. Jackets are useful to keep calves warm from birth to three weeks, whilst ensuring they are bedded on clean, dry straw in a draught free environment.

Finally, measure and monitor: your heifer calves will need to gain 800g/day throughout
the rearing period if they are to double their birth weight by weaning and go on to reach 85
– 90% of mature weight by calving at 23 to 25 months, weigh your animals regularly to ensure they are hitting these targets

* Adapted from Soberon & Van Amburgh 2013

Attention to detail: Part 1

Unlocking potential in the milk drinking phase

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Did you know that if you increase your heifer calves’ daily liveweight gain from 500g to 800g in the milk drinking phase, then they’ll have the potential to increase yield by an average 450 litres in first lactation?

Unlocking that potential is all about attention to management detail. Here are five fundamentals.

1. Mixing: Don’t get confused!

If you are following instructions to make up one litre of milk, then you need to add 125g of calf milk replacer powder (CMR) to 875ml of water equating to a 12.5% concentration. Adding 125g of the same CMR to one litre of water will lower the milk concentration to 11.1%. On a system feeding six litres per day, that would equate to 4.7kg less CMR over a 56 milk day period.

Download our Farmers Guide to Mixing Milk here.

2.Scoop calibration: CMR is a natural product so bulk density can vary between batches.

Calibrate your CMR scoop between batches by measuring a level scoop and weighing it. Take a scoop holding 375g, but you think it holds 450g and you’re aiming to feed 900g per day, then you could be underfeeding by a significant 150g per day.

3. Scoop cleaning: do you regularly clean and dry your measuring scoop?

A scoop with a build-up of CMR could significantly impact on the amount you are actually feeding each day. For example, 5g of dirt or hard powder in a 150g scoop could mean you’re feeding 30g per day less than you thought when feeding daily 900g per day measured using a 150g scoop.

4. Mixing temperature: aim for 40°C.

Scalding temperatures will denature milk proteins and reduce the quality of milk solids fed.

5. Feeding temperature: aim for 37°C.

Milk should be fed between 37-39°C to stimulate a strong oesophageal groove reflex, which helps prevent milk entering the rumen. The spillage of milk into the rumen will increase the risk of scours or bloat which could result in poor growth rates. If you are feeding a long line of calves, ask yourself – is one at the end getting the same temperature milk as the one at the start? Think of ways around it, for example using a milk shuttle to keep the milk warm.

Inaccurate measuring over a prolonged period can impact pre-wean growth and your calves weaning date.

Next week we’ll investigate some more fundamentals.

Source: Adapted from Soberon and Van Amburgh, 2013