Successful rearing from birth to weaning

A successful heifer-rearing programme would include a healthy calf, achieving optimum growth rates and a successful weaning while hitting performance targets so she can calve down into the herd at 22-24 months, giving her the best opportunity to reach her future lifetime milk production. Getting the basics right from day one needs to be a priority for all calves born on farms this spring. There are five key areas that must be considered to rear healthy calves and keep mortality to a minimum, these include:

Colostrum;

Early life nutrition;

Rumen development and immunity;

Environment; and

Successful weaning.

Colostrum

The first few hours of a calf’s life are critical in determining its future health. High-quality, clean colostrum given at the right time, and in the right amount, provides a foundation for success during any calf-rearing season. A calf is born with no active immune system to protect against disease and depends solely on passive immunity from colostrum feeding. After the first few hours of birth the ability for a calf to absorb essential antibodies from colostrum reduces significantly as the gut barrier loses permeability. Quality of colostrum also needs to be considered; high quality colostrum contains at least 50g/L of immunoglobulin G. Colostrum should be measured with a refractometer – these are widely available and quite inexpensive. 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. It is important to maintain this high standard for colostrum feeding throughout the entire calving season.

Early nutrition

During the first few months, a calf is most efficient at turning feed into weight gain. One of our targets is to double the birth weight by time of weaning. To achieve this, a 40kg calf needs to gain 0.6kg per day. Current recommendations for feeding dairy calves include offering 15 per cent of its body weight in whole milk or milk replacer mixed at 125g/L of water. This equals six litres per day.

Remember, as calves grow, they will require more energy, so volume and concentration must be increased.

During colder weather, calves will have a higher energy requirement because they will use a lot of energy to stay warm rather than put on weight. It is important to increase the volume and concentration of milk replacer in response to cold weather.
When it comes to milk replacers, it is important to know what you are purchasing. To achieve optimal growth rates, a milk replacer should contain 20-25 per cent crude protein, 18-20 per cent fat and less than 8 per cent ash, and it should be matched to meet the desired growth targets. 

Rumen development and immunity

Calf rearing will take up a large proportion of the morning and evening routine on most farms. It can be time-consuming at the best of times but can be particularly frustrating if calves’ immunity is compromised. At birth, the rumen is underdeveloped and cannot contribute to digestion. A well-developed rumen is essential for optimising feed efficiency and ensuring weight gain targets are achieved before and after weaning. To develop the rumen papillae, we must provide the calf with concentrates, fibre and water to allow rumen microbes to grow and multiply. The calf will only eat small amounts in the first few weeks. It is important that they are offered coarse ration from day one. As the calf starts to eat concentrate, they start to digest starch, which produces volatile fatty acids called propionic and butyrate.
The use of 8-10 per cent of chopped straw as part of the calf concentrate can encourage rumen strength and papillae development. When forages are digested, they predominately produce volatile fatty acid such as acetate. Feeds high in fibre give a warming effect to calves as acetate is produced. 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 it is converted to an energy source for rumen-wall growth.
Water is a vital part of calf nutrition and one that is often disregarded if they are on milk. Clean, fresh water should be readily available from week one. The development of calf starter intake depends on water intake. It is important to remember that milk goes into the abomasum, bypassing the rumen, hence there is no water/moisture to aid the digestion of the calf concentrate in the rumen.
Scours are responsible for nearly 30 per cent of deaths in calves, while also resulting in poor growth and poor performance, and a lot of work for the farmer. Prevention is better than cure, and a lot can be done to help prevent diarrhoea problems on a dairy farm.

Environment

Suitable calf housing is an important factor to consider for rearing healthy calves. Calves spend 80 per cent of their time lying down and need a dry, draught-free bed with good air flow, space and light. The shed should be thoroughly cleaned and disinfected with a broad-spectrum disinfectant before calves arrive. While in use, pens should also be frequently disinfected to prevent the build-up of disease organisms.