During the first few weeks of life, calves are unable to eat enough dry feed to meet their energy requirements and are almost entirely dependent on milk. The pathway to calf health starts with sufficient high-quality colostrum within 12 hours of birth. A newly born calf’s ability to absorb immunoglobulins in colostrum reduces significantly from about six hours and has gone completely by 24 hours (Source; AHDB Better Returns).
Colostrum quality depends heavily on the cow’s body condition at calving and her pre-calving diet. Maintaining a body condition score (BCS) of calving cows between 2.5 and 3 between late pregnancy and bulling ensures enough quality colostrum is available at calving. This is relevant for sucklers as well as in diary units where calves are then reared on milk replacer.
A recent Royal Veterinary College (RVC) study suggested more than half the replacement dairy heifers could be growing too slowly to hit targets for optimal health and lifetime productivity. Never reaching their genetic potential or optimum number of lactations to recoup herd replacement selection and rearing investments
(Source; VOLAC. Feed for Growth).
Milk replacer should contain 20–26% crude protein and 18–20% fat to achieve optimal growth rates in early life. The exact amount to feed depends on calf liveweight, target growth rate, environmental conditions and the nutritional makeup of what is being used (Source; AHDB Better Returns).
Manufacturer’s instructions should be read & followed
Everyone involved needs to prepare feeds in the same way
Feeding at the same time each day, at the same temperature & at the same concentration
Avoid changing products avoiding digestive upsets & negative impacts on performance.
Milk powder should be made up with warm water at 45°C and fed at 37–39°C. Cleanliness is paramount. Equipment should be cleaned between feeds, using detergent for feeders or buckets (see Table 1 below).
(Source; AHDB Better Returns)
Selecting higher quality calf feeding equipment ensures longevity but also assists in hygiene. As such, feeders made from polyethylene that is both tough and durable but easily cleaned is preferable. Open tops and ergonomically moulded units can be thoroughly cleaned quicker and easier. Less milk residue build-up and the ability to dry naturally after cleaning reduce bacteria growth. Other factors to consider are the type of teat to use with better-quality makes that actively encourage young calves to feed from the onset. Easily removable teats also encourage better hygiene practises too.
Pneumonia is estimated to cost the UK cattle industry more than £60m/year (Source; AHDB). A bout of pneumonia if not fatal, often sees irreversible lung damage, a ‘Poor doer’ susceptible to disease from then on.
The important viral causes of respiratory disease are Infectious Bovine Rhinotracheitis (IBR), Bovine Respiratory Syncytial Virus (BRSV) and Parainfluenza-3 virus (PI3).
There is a variety of bacteria associated with pneumonia including Mannheimia haemolytica, Pasteurella multocida, Histophilus somni and Mycoplasma bovis.
The presence of Bovine Viral Diarrhoea (BVD) can also be linked to some pneumonia outbreaks due to weakened immunity within a batch of calves exposed from a Persistently Infected (PI) host.
Mycoplasma is a bacterium that can cause pneumonia and ear, eye and joint infections. It is introduced by infected calves and can spread rapidly between calves using shared teats and through respiratory secretions.
Scour is the most common disease in young calves, accounting for about 50% of all calf deaths. The disease can be easily recognised, but it is essential that treatment is administered rapidly to maximise the chance of survival.
Scours can be caused by a whole host of pathogens including cryptosporidiosis, rotavirus, coccidiosis, coronavirus, E. Coli and salmonella.
Cryptosporidiosis is a very common cause of scour in calves who are usually infected with the Cryptosporidium parasite shortly after birth and then start to scour around a week old.
Coccidiosis is a disease caused by coccidia, which are small parasites that damage the lining of the intestine. Calves eating, drinking or licking contaminated feed, water or objects spread this infection (Source: AHDB Better Returns).
Hygiene of equipment and facilities, therefore, can go a long to prevent or reduce the spread of issues highlighted. Calves will sometimes get nutritional scours, caused by inconsistent feeding. These can be minimised by ensuring milk is always prepared and fed in the same way.
Vaccination provides effective control of the common viral and some of the bacterial causes of pneumonia. They should be used before high-risk periods to minimise the risk of disease. They cannot be a cure all solution and other factors need to be considered, for example; ventilation in sheds and mixing animals of varying ages. Timely and accurate vaccination needs to be undertaken and this can be a conventional needle vaccination or via intranasal delivery. Accurate vaccinators either bottle mounted, tube fed or with a Repeater are easier and more accurate that a syringe and needle cleaning systems also reduce the spread of infection or risk of abscesses.
The RVC calf study suggested growth rates of at least 0.7kg per day are preferable in most dairy units. Calves therefore need at least 750g of milk powder per day as well as calf starter ad lib which ‘interests them’ ie. Is very palatable and is regularly changed. Clean straw (not hay) as forage to pick at and clean water all contribute to optimum daily liveweight gain (DLWG) and rumen development.
In calf rearing, DLWG is one of the most important key performance indicators of performance and benchmarking can deliver benefits even if everything seems satisfactory and only fine tuning is required.
Calves can be weighed easily on portable systems such as platforms with load bars connected to digital weigh heads. EID tags or visual numbers can be read or recorded, and valuable data collected.