ON busy dairy farms with daily pressures of milking, feeding and cleaning, the rearing of calves may not always take high priority. However, the heifer calves become the future milking herd and so they need the best possible start in life to achieve their potential and contribute to the business.
Trevor Alcorn, CAFRE dairying development adviser, says: “Rearing dairy heifer calves is the second largest annual expense for dairy farms, accounting for about 20 per cent of production costs. It is critical that farmers pay close attention to detail, from before birth and up to weaning, to ensure healthy calves.”
Trevor advises that the management for healthy calves starts pre-calving. The milking cow should be dried off at least six to eight weeks before calving to ensure sufficient time to produce quality colostrum.
A high yielding cow with a low body condition at drying off will require a pre-calver concentrate ration but certainly all cows should receive dry cow minerals to maintain the required vitamin and mineral status of both cow and developing calf. Ideally the cow should be calving at an optimum body condition score of 3, that is not too fat nor too thin.
A number of farmers also use the dry period as an opportunity to vaccinate cows against some of the agents which cause calf scour (eg, Rotavirus or E-coli). The derived immunity is passed on to the unborn calf. If Rotavirus or E-coli have been diagnosed as a persistent problem, then consult your local vet to discuss if a vaccination programme would be beneficial.
Trevor advises: “The calving environment should be as clean as possible with dry bedding to minimise disease risk. Disinfected calving aids should be ready for use. Once the calf is born make sure that its airway is clear and that it can breathe properly. The naval should be treated after birth with an iodine solution dip to prevent the onset of joint-ill. Dipping gives better results than spraying.”
Colostrum is essential to calf health. Baby calves have no active immunity at birth and must receive between three and five litres of colostrum as soon as possible after birth. This should preferably be from a teat to establish a good suckling reflex.
Feed a minimum of six litres in the first 12 hours. The level of antibodies in the colostrum decreases with each milking as does the calf’s ability to absorb antibodies into its system. Calves are unable to absorb antibodies from the intestine after 24-36 hours.
Maintaining calf health and thrive is achieved by good feeding and housing management and attention to disease control. Trevor continues: “Scours and respiratory problems are the two main causes of illness common in young calves. It is a real challenge to every farmer to control the onset of illness and reduce the impact of the disease on the calf health.”
Scour is the biggest killer of calves under one month of age resulting in three per cent mortality with around 50 per cent of scours caused by poor hygiene. Causes of nutritional scour include lack of sufficient colostrum after birth, too much milk or in the case of a milk replacement product it could be too concentrated, lumpy and not properly mixed. Irregular feeding can cause problems and a lack of consistent amounts. Cold, damp, draughty or humid housing can also cause susceptibility to scour.
Infectious scours are caused by a number of pathogens. All scour outbreaks should be investigated early by consulting your vet who can arrange for faecal samples to be sent to AFBI Veterinary Sciences Division to identify the pathogen causing the problem. Some vets offer a quick diagnostic faecal sample test on farm. Pathogens are often picked up from the environment, so lack of cleanliness in the calving area and in the calf rearing house are major risk factors.
Always isolate infected calves in a warm environment and treat them according to the source of the scour. Your vet will provide advice on vaccination and suggest a future prevention health plan.
Pneumonia is a respiratory disease that reduces performance and unless treated effectively will result in the death of the calf. Pneumonia is the most common cause of death in one to six-month- old calves. A number of different infectious agents can be involved in an outbreak, with BRSV and PI3 the most common primary agents. Again consult your vet on the most suitable treatment and discuss a vaccination programme that can help protect the calf against these and other pathogens.
Poor housing and ventilation are among the main causes of pneumonia. High humidity caused by damp bedding, poor air movement or overcrowding can lead to a tenfold increase in the number of infectious organisms and the time they survive. Stress, inadequate colostrum feeding and high levels of atmospheric ammonia are other factors that predispose calves to infection.
Steps to prevent pneumonia include ensuring adequate colostrum intake, keeping the bedding dry with good drainage and frequent cleaning. Provide effective ventilation in calf sheds although try to avoid draughts at calf level. Avoid overcrowding and try not to mix different ages of stock in the same shed. Aim to minimise general stress on the young calf.
Calves are generally fed whole milk or milk replacement products up to at least 6-8 weeks old. A good quality calf concentrate or coarse mix should be offered from one week of age. Always ensure access to hay or straw as the long fibre will help develop the calf rumen. Clean water should always be easily available.
Trevor suggests: “Many farmers now use automatic feeders for batches of calves thus reducing labour requirement. However remember to walk through the calves regularly allowing the calves to get used to human contact. This should encourage calves to be quieter, more easily managed and milked when mature.”
Calves can be weaned when they are eating at least 1kg of calf concentrate and after weaning increase to 2kgs per day, along with forage.
Trevor summarises: “The management adopted during the calf rearing period has a major impact on heifer rearing costs and milking performance.
“Farmers should ensure that calves get the best possible start in life and do not suffer any serious setbacks caused by health problems. Heifer rearing, although costly and time consuming, can be rewarding with an enjoyable outcome of fine healthy heifers to be the next generation of the dairy herd.”