Immunity and nutrition are vital to calf performance

By Lauren Henry,

InTouch Feeding Specialist, Alltech Ireland

THE heifer calf is the future of your dairy herd; therefore, careful attention should be paid to ensure she becomes a profitable, productive an-imal.

This starts with a successful dry cow programme, allowing a healthy calf to be born. Then we can focus on achieving optimal growth rates, successful weaning and hitting performance targets so she calves into the herd at 24 months, giving her the best chance at reaching her future lifetime milk production.

It is important to get the basics right. Five key areas to focus on are:

n Colostrum;

n Early life nutrition;

n Rumen development;

n Environment and immunity;

n Successful weaning.

Colostrum

When it comes to colostrum, there is only one opportunity to get this right. The first few hours of a calf’s life are probably the most critical because what happens during this time will have a lasting impact on the lifetime production and profitability of the animal.

Good quality, clean colostrum given at the right time and in the right amount provides a foundation for success for any calf-rearing enterprise.

The calf’s immune system is not fully functional in the first months, so the calf needs the antibodies from the colostrum to protect it against pathogens and disease. The calf’s ability to absorb these antibodies is at its highest in the first hour of life, so it is essential to get colostrum into the calf quickly.

The absorption rate declines rapidly thereafter and will com-pletely cease at 24 hours. Colostrum should also be tested using a colostrometer or Brix refractometer; unless you test the colostrum, you cannot determine its quality.

The quality can vary a lot between animals and is affected by age, length of dry period, vaccinations, breed and time collected post-calving.

High-quality colostrum should con-

tain at least 50g/L immunoglobulin G. A study in Northern Ireland revealed that 44 per cent of samples reported

IgG concentration below target (<50mg/ml).

The golden rule is to get at least three litres of colostrum into the calf within two hours of birth for the first feed (this is the “3-2-1” rule).

Early life nutrition

Feed efficiency is at its greatest in the first few months of life, so we need to capitalise on this. One of our targets is to double the birth weight by weaning. To achieve this, a 40kg calve must gain 0.6kg per day. It is a challenge to achieve this performance; correct feeding strategies must be implemented to do so.

It has been found that 25 per cent of heifer calves grow at <600g/day during their first six months. This is directly linked to increased age at first calving, reduced reproductive performance and reduced yield in first lactation.

Current recommendations for feed-

ing dairy calves are to offer 15 per cent of the body weight in whole milk or milk replacer mixed at 125g/L water: this equals six litres per day.

As the calves grow, they will require more energy, so volume or concentration must be increased. Also, remember, coming into colder weather, calves will have a higher requirement for energy as they will partition it into keeping warm before growth. So again, a higher volume or concentration should be offered.

Using a milk replacer is re-commended to reduce the risk of disease transfer and ensure consistency of the product being fed, so fewer digestive upsets and incidence of scours.

However, choosing a milk replacer and understanding the label can be difficult.

To achieve optimal growth rates, a milk replacer should contain 20-26 per cent crude protein, 16-20 per cent fat, less than eight per cent ash and be matched to meet the desired growth targets. For every 100g daily gain pre-weaning, the heifer can give 150-155kg more milk in the first lactation.

Rumen development

At birth, the rumen is under-developed and cannot contribute to digestion; therefore, we must provide the calf with concentrates, fibre, and water to allow rumen microbes to grow and multiply. Although the calf will only eat small amounts in the first few weeks, they must be offered from day 1.

As the calf starts to eat concentrate, they begin to digest starch, which produces propionic and butyric acids. Using 8-10 per cent chopped straw as part of the calf concentrate can encourage rumen strength and papillae development.

When forages are digested, they predominately produce acetic acid. Acetic and propionic acids are absorbed through the rumen wall and are converted to metabolites as an energy source for growth.

Butyric acid is not absorbed through the rumen wall but is converted into an energy source for rumen wall growth. The rumen pH gradually rises as development continues.

Water is another vital component of calf nutrition and something we often take for granted.

Water should be available to calves, separate from milk, at all times. Any milk consumed goes straight to the abomasum, bypassing the rumen, so there is no water to aid the digestion of the calf concentrate in the rumen. Providing water can increase growth rates by 38 per cent and starter/concentrate intakes by 31 per cent.

Environment

Calves spend 80 per cent of their time lying down. Therefore, for the calf to thrive, it must have a comfortable, dry space with good airflow, space and light. It is also best practice to keep calves in the same group and of similar ages. Even in colder weather, calves need plenty of fresh air, but draughts at calf level must be avoided.

The shed should be thoroughly cleaned and disinfected between calves with a broad-spectrum disinfectant. While in use, pens should be frequently disinfected to prevent the build-up of disease.

Hygiene around milk feeding is also vital: cleaning all feeding equipment is necessary for maintaining healthy animals, and prioritising feeding younger animals first, along with rinsing before feeding the other batches, will help alleviate the spread of disease.

Successful weaning

For a successful weaning process we need to reduce stress and disease to minimise disruption of growth rates. Weaning should be done gradually by reducing the volume of milk or the number of feeds over 7-14 days. This allows the calf to replace energy from the milk replacer by increasing concentrate intakes and avoids growth checks at weaning. From a nutritional view, the most suitable time to wean the calf is when they are eating enough concentrate.

It is recommended that they eat 2kg of calf starter for three consecutive days as this indicates good rumen development.

The Alltech solution

At Alltech we aim to help farmers raise healthy, productive animals. To achieve this, we have developed nutritional products and services to support the first critical months of a calf’s life. Including Actigen in the diet will benefit the calve by modifying and improving the intestinal microflora composition.

Actigen has been proven to help manage the risk of diarrhoea in calves and improve feed conversion efficiency while increasing starter intake and weight gain. Actigen can give calves the best possible start to build a strong immune system.

It can be used to reduce scour in calves and, as a yeast-based product, improve feed efficiency. Actigen can be included in the milk replacer or calf ration at an average inclusion rate of 1.5 g/day.