The Veanavite® calf rearing system is well renowned and encompasses all aspects of successful calf rearing. The Veanavite rearing system is designed to enhance natural rumen development whilst ensuring the healthy growth of the calf. 

Golden rules for rearing healthy calves

• Select and rear good quality calves
• Provide adequate colostrum within the recommended time frame (see below under Colostrum)
• Take preventative action for navel and respiratory infections
• Introduced calves should be given quality electrolyte on arrival
• House calves in clean, dry, well ventilated draught-free housing with 1.5 square metres of space per calf
• Feed Veanavite^® Farmyard and follow mixing and feeding instructions
• Provide good clean straw and clean water at all times in close proximity to milk and pellet feeders
• Allow unrestricted access to Veanavite^® No 1 Calf Pellets from day 1 of the feeding program
• Calves can be weaned off milk when consuming a minimum of 750 g to 1 kg of pellets per head per day
• House calves off pasture until 10 to 12 weeks of age
• Feed Veanavite^® No 2 Weaner Calf Pellets to supplement the pasture phase and maintain growth rates until joining
• Maintain good preventative health management and respond quickly to any problems that occur
• Ensure facility is completely cleaned out and spray pens with anti-viral anti-bacterial spray between batches of calves

Correct colostrum management is fundamental to any calf rearing program. Colostrum is the first milk from the cow containing high concentrations of antibodies (immunoglobulins), protein, energy, minerals and other essential nutrients for calf survival and future health and well-being. Antibodies are complex proteins designed to combat infection.

The newborn calf has little active immunity against disease and must absorb antibodies from the colostrum through the wall of the intestine to gain protection. The calf's ability to absorb antibodies from colostrum is highest at birth and declines in the following 24 hours. Ideally, calves should receive 2 litres of good quality colostrum within one hour of birth, and a further 2 litres within the following 12 hours.

Some practical measures can be employed to ensure the intake of colostrum at the correct time is optimised. Feeding cows an appropriate transition diet containing anionic salts 21 days prior to calving ensures calves are born with reduced difficulties, allowing access to colostrum before their ability to absorb antibodies decline. A measured dose of colostrum should then either be suckled by the calf or alternatively delivered directly by stomach tube.

Colostrum quality varies with age, breed and health status of the dam and can be tested for the level of antibodies with a brix refractrometer. High quality colostrum can be frozen in plastic bags or containers. It should be thawed by placing in a bucket of warm water. Do not use a microwave oven.

The navel of a newborn calf is the simplest and most likely site for direct infection to enter the calf. To prevent navel infections, ensure the navel is clean and dry by treating the navel with a 5% iodine solution as soon as possible after birth. Always calve on clean dry ground and rotate calving paddocks.

Problems that may arise from navel infection include:

• Joint ill – swollen front knees being the most common;
• Blood poisoning (septicaemia) resulting in sudden death in the first week; and
• Local infections of the navel.

For infections of this nature, consult your veterinarian.

The immune system of the calf is not fully functional until about 12 weeks of age. The calf is very susceptible to infections from airborne pathogens and lung damage from ammonia in the atmosphere. Calves can harbour sub-clinical infections that develop into pneumonia when the calves are subjected to environmental stresses.

The most common circumstance leading to lung infections is poor ventilation. Poor ventilation causes an increase in the humidity and temperature inside the housing and creates the perfect environment for bacteria and viruses to thrive. The build-up of gases such as ammonia under conditions of poor ventilation damages the lungs and makes them more susceptible to infection. In addition, high pressure hosing near calves should be avoided as the mist given off contains bacteria from manure which are inhaled by the calves.

Lung infections can be minimised by ensuring calf housing has adequate, draught-free ventilation. Calf housing should have flow-through ventilation, starting above calf height to avoid draughts. Awnings should be used on the side of the prevailing weather to prevent rain entering but still allow ample air flow.

Scours accounts for more than 60% of all calf deaths, therefore vigilance and rapid treatment of scours is essential. Scours is the general term used to describe a variety of conditions in calves, characterised by a major loss of water and nutrients in the faeces, resulting in rapid dehydration and often death.

Most scours are caused by environmental stresses such as transportation, overfeeding, feeding changes or feeding poor quality products. These stresses can lead to outbreaks of infectious scours caused by agents such as bacteria (E. coli, Salmonella), viruses (Rotavirus) or protozoa (Coccidia). Adequate colostrum intake gives calves a first line of defence against scours.

Non-infectious or nutritional scours are due to digestive imbalances which disrupt the natural processes of digestion. Digestive imbalances cause physical discomfort and upset the osmotic balance of the calf. In addition, the pH of the intestines may change from optimal conditions, further increasing the risk of bacterial infections.

Understanding the process of milk digestion in the calf has enabled the development of feeding programs and products to reduce calf scours. When a calf drinks milk, the milk bypasses the first three stomachs to enter the fourth stomach or abomasum. Rennet causes the milk casein to clot within the acidic environment of the abomasum which is unfavourable to harmful bacteria. The casein in Veanavite^® Farmyard clots readily to assist this process.

The acid condition of the upper intestine further prevents harmful bacteria from invading the small intestine and causing infections. Under ideal conditions, the digested material passes slowly through the small intestine where the majority of digestion and absorption takes place.

Calves with infectious scours often appear dull, listless and off their feed. These calves require veterinary treatment for the infection as well as quality electrolyte therapy to keep them hydrated and to restore the balance of salts in the body. Feed electrolytes as per package instructions until the calf is feeding normally again.

Always consult your veterinarian in these cases to identify the type of infection and to obtain the appropriate treatment for the infection.

Coccidiosis is caused by a protozoan – not a bacteria or virus. It causes infection of the intestine starting as a white scour and turning to a blood scour as the lining of the intestine is damaged. Most soils contain coccidia and all calves are susceptible to coccidiosis until about 3 months of age when resistance develops. Heavy stocking rates and wet conditions are conducive to coccidiosis outbreaks. Once a calf has coccidiosis, it must be treated by your veterinarian.

Coccidiostats in calf pellets or meals will not control the pathogen until calves are consuming approximately 1 kg of pellets per day, typically 5–8 weeks of age. Until this time prevention must come via the daily milk ration, which can be sourced as a powder or liquid additive product.
 

If calves are housed without access to pasture they will be relatively worm-free. Slats and deep litter (sawdust, rice hulls etc) are not conducive to worm egg survival and calves are not eating off the ground to pick up worm eggs.

Rearing calves in calf paddocks, particularly with year-round calving, creates severe worm problems. Worm burdens build up and calves have little resistance to them, often resulting in scours and severe growth checks.

Worm problems are unlikely to cause scouring in calves less than 6 weeks old; however drenches are very effective for treatment of worm infections in calves. Regular worm control is essential once calves have access to pasture.

All calves should be vaccinated against clostridial diseases and adults should be given an annual booster. It is essential that 2 doses of vaccine are given to calves: the first at about 6 to 8 weeks of age and the second 4 to 6 weeks later. If cows are vaccinated, passive immunity is passed on to calves which covers them for the first 6 to 8 weeks of life.

Replacement heifers for the dairy herd should also be vaccinated for Leptospirosis.

To maintain a clean calf rearing environment, use a good quality disinfectant according to the manufacturer's instructions. The disinfectant should be effective against the many viruses and bacteria harmful to calves. Bedding conditioners can be sprinkled on clean floors or applied to the bedding to reduce the risk of infection and keep the bedding dry for animal comfort.

Calves have a natural preference to eat pasture or good quality hay, however early consumption of these materials will severely restrict the speed of rumen development and may be harmful to the health and well being of the animal. When feeding for rumen development:

• House the calf off pasture for the first 10 to 12 weeks to encourage pellet consumption;
• Ensure calf housing is clean, warm, dry, well ventilated, draught free and well lit: decontaminate housing between batches of calves
• House calves at 7 calves per pen maximum
• Allow 1.5 square metres per calf for individual pens and group pens on deep litter (rice hulls, sawdust, wood shavings, straw etc) or 1.1 square metres per calf on timber slatted floors

Timber slatted floors should be made of 50 mm wide x 25 mm thick hardwood and should have a gap of 30 mm between slats. Mesh floors of any kind are not recommended as they are cold, hard, expensive and difficult to clean.

At birth, the rumen represents approximately 30 per cent of total stomach capacity and the abomasum 55 per cent in the calf. In the mature animal, rumen capacity is around 80 per cent, whilst the abomasum represents about 10 per cent. This reflects the natural development of the rumen as a result of the gradual change from a predominantly milk diet in the young calf to a solid diet in the mature animal (see diagram below, Moran, 1993, Victorian Department of Agriculture).

A developed and functional rumen can only be developed by a number of physical and chemical processes. A developed and functional rumen will have muscular tone, a population of appropriate bacteria, nutrient absorptive capacity and enough size to process adequate volumes of feed. The speed of rumen development is not controlled by the calf's age or weight but by the diet fed to the animal and the physical and chemical processes associated with its digestion. The process of rumen digestion converts feedstuffs into compounds that can be readily utilised and ultimately provide the energy and protein required by the animal. These compounds are absorbed directly from the rumen or are absorbed further down the digestive tract and are essential for the maintenance, growth and development of the calf.

Therefore, nutrition and general health of the calf will determine the rate of rumen development. There is a significant difference in the time taken to develop a functional rumen in a calf reared on a cow or fed a diet with unrestricted milk in comparison to a calf reared in an early weaning system, which includes pellets and straw and is designed to promote rapid rumen development.
 

The milk feeding regime is vital to the Veanavite^® calf rearing system. During the milk phase, the aim is to encourage pellet consumption by allowing unrestricted feeding of pellets from day 1. Calves can be fed milk at any time of day as long as the timing is consistent.

Veanavite^® Farmyard is suitable for use in automatic calf feeding machines or fortifying with whole milk.

When milk is consumed by the young calf, it passes directly into the fourth or true stomach (abomasum) via a vessel called the oesophageal groove whilst the pellets and other dry feeds directly enter the rumen. Veanavite^® No 1 Calf Pellets play a critical role in the development of the rumen and are formulated for this function. The consumption of dry feedstuffs, balanced for protein and energy, provides the right substrates to develop a microbial population. Importantly, Veanavite^® No 1 Calf Pellets contain a blend of carbohydrates and high quality proteins that are readily fermentable, which is essential for the rumen microorganisms to function and multiply.

Pellets are fermented by rumen microbes into compounds called Volatile Fatty Acids (VFAs). Volatile Fatty Acids provide a primary source of energy to the calf and are absorbed through the rumen wall via small blood vessel-rich protrusions called papillae. It is the VFAs, or by-products of microbial fermentation, that provide the chemical stimulus for the development of the blood vessel-rich surface of the rumen. The microbes that ferment the feed are themselves digested and ultimately provide the calf with an ideal source of protein. In a healthy, developed rumen the microorganisms flow in a steady stream from the rumen and are eventually absorbed as a near-perfect balance of amino acids from the small intestine.

Thus, feeding pellets is an excellent way to start rumen development within a few days of birth.

Clean straw is an important ingredient to promote early rumen development in any weaning program. Clean bright barley straw is preferred and should be placed in close proximity to other feed sources to ensure consumption to maintain a stable rumen environment.

Straw is essential particularly after weaning when pellet intake increases rapidly and the calf is at a higher risk of suffering from acidosis. Acidosis kills off rumen microbes and damages the rumen wall which results in decreased feed intake, digestibility and growth rate. Acute cases can rapidly result in death. It is important to maintain a regular eating pattern that promotes a stable and healthy rumen environment.

Chemical buffers, such as sodium bicarbonate, are added to pellets to reduce the risk of acidosis but straw is a vital ingredient to promote healthy rumen function. Straw provides little or no feed value but does provide long fibre which helps develop the rumen's size and muscular rhythm. The length of the straw and dwell time in the rumen promotes the cud-chewing reflex that in turn stimulates the flow of bicarbonate from saliva, the calf's natural buffer, into the rumen. Thus freely available straw is essential.

When both pellets and straw are fed unrestricted, a healthy calf, free of digestive problems, will naturally balance the intake of both to maintain the pH in the rumen. A calf will consume about 1 small bale of straw during its 10 to 12 week rearing period.

Clean fresh water is essential for life and rumen development. The rumen is a large fermentation vessel and will cease to function without an adequate supply of clean water. Water troughs should be cleaned out daily.

Small self-filling waterers holding approximately 2 litres with a push out plug are ideal and can water up to 20 calves easily.

 

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The calf may be introduced to pasture at 10 to 12 weeks. The ultimate aim of the Veanavite^® rearing system is to produce a calf that can efficiently utilise pasture at an early age as practical. It is important to provide a transition period during this phase to ensure that no digestive disturbances occur. The calf will require supplementary feeding with Veanavite^® No 1 Calf Pellets at 1 to 2 kg per day for 2 to 3 weeks minimum during the transition period to pasture. During this transition period, the population of grass-digesting bacteria in the rumen gradually increases.

Veanavite^® No 2 Weaner Calf Pellets are formulated to supplement calves at pasture after the transition period. The ongoing performance of the calf will depend on the quality and quantity of pasture available. At this stage, rumen volume still limits pasture consumption so growth is maximised by feeding Veanavite^® No 2 Weaner Calf Pellets to balance any nutrient shortages. Weight gain up to joining can be maximised by continued supplementation with Veanavite^® No 2 Weaner Calf Pellets or Veanavite^® No 3 Heifer Developer Pellets. Some additional roughage to provide dietary fibre may be required on lush pasture.