You asked, we answered. Vet Keryn tackles your calf rearing questions.
Q. How often should we be picking up (and why)?
The more often calves can be picked up, the better, but a minimum of twice daily is recommended.
Calves are born with poorly developed immune systems and require the antibodies from colostrum to protect them from infection. However, the antibodies can only be absorbed by the gut for a short time after birth, so it is important that calves are picked up and fed at least 2L of gold colostrum within 6-12 hours of birth (the sooner they get it, the more antibodies they can absorb).
If just left with their mothers, many calves do not drink enough to get the antibodies they need. When calves are only picked up once a day, some will be almost a day old before they enter the shed, which is too late to get antibodies into them if they have missed out.
Picking up calves more often has other advantages too:
Calf wastage is likely to be reduced due to fewer deaths in the paddock;
Cows return to eating sooner when they have less time to bond with their calves/spend less time looking for them;
This helps to reduce the incidence of metabolic disease and minimise loss of body weight after calving, which in turn has benefits in terms of milk production and in-calf rates at the subsequent mating.
Q. Milk powder or fresh milk, what's the gold standard?
There are pros and cons to both, so pick whichever best suits your system.
Healthy calves can be raised successfully on either. However, not all milk powders are created equal, so if feeding powdered milk, ensure a good quality powder is used.
Whole milk contains more fat than most milk powders, so is often a better energy source, whereas milk replacers have a higher protein to fat ratio, which encourages intake.
Cheaper powder formulations may use protein sources that don’t meet the amino acid requirements of the calves and excessive heating during manufacture can adversely affect calf digestion of some powders. Good quality powders will be nutritionally similar to fresh milk.
There are some diseases which may be transmitted to calves by feeding fresh milk, such as Johne’s disease, Bovine Viral Diarrhoea (BVD) or Mycoplasma bovis. Pasteurisation or acidification of the milk can kill these organisms.
Antibiotics in milk can create antibiotic residues in calves and also promote the development of antibiotic resistance, so waste milk from treated cows should not be fed to calves.
These problems are not encountered with the use of milk powders, but improper mixing, irregular feeding intervals, or feeding powdered milk at the wrong temperature may cause ruminal bloat.
The availability of fresh milk, cost and convenience may also influence your decision on which to feed.
Q. Colostrum - what's the best way to test it, can it be preserved and how long do we need to feed it to the calves?
Colostrum quality is determined by both antibody content (which should be high) and bacterial load (which should be low). The appearance of the colostrum is not an indicator of quality - it may look creamy and yellow, but still be low in antibodies, or full of bacteria!
The best way to estimate antibody levels in colostrum is to use a Brix refractometer. These are small handheld instruments that measure the density of a solution, which, in the case of colostrum, is proportional to antibody content.
A refractometer is quick and easy to use. To ensure newborn calves obtain sufficient antibodies, colostrum with a Brix reading of 25 or greater should be fed.
Best practice is to measure each cow’s colostrum individually and save the best quality for newborns. Lower quality colostrum can be fed to older calves.
There is no practical way to measure bacterial load on-farm, but this can be minimised by:
Ensuring all utensils used in the collection, storage and feeding of colostrum are clean, and the colostrum is correctly stored;
Using metal buckets over plastic ones, as they are less likely to have scratches in the surface that may harbour bacteria. Lids are essential;
Pasteurising and then freezing colostrum to kill bacteria and preserve it. For overnight storage, colostrum should be refrigerated, but for longer term storage, it should be frozen or a preservative added. Frozen colostrum will keep for up to a year, but antibody levels will decline over time;
Using colostrum keepers such as citric acid or potassium sorbate to acidify milk, preventing bacterial growth. This enables it to be fed to older calves for 3-4 weeks. Yoghurtisation is another means of acidification.
Newborn calves should always receive fresh colostrum to allow maximum absorption of antibodies.
Q. Navels, what's best practice?
Navels should be sprayed with iodine as soon as the calf is picked up in the paddock, as it is being loaded into the calf trailer.
Also, avoid overcrowding the trailer to prevent calves from standing on each other’s navels during transport.
Inspect and spray them again on entry to the shed, and then daily until the navel is dry. Minor infections can be treated with antibiotics, but more severe ones may need surgical drainage by your vet.
Q. What are your tips for transitioning calves from pen to paddock?
Calves should be kept inside for a minimum of 3 weeks, but preferably longer in cold, wet or windy weather.
Having some transitional pens, where the calves can be outside but still access the calf shed at night, is ideal. If this is available, calves can be outside during the day from a week old.
Calf paddocks should always have some form of shelter in the way of trees, hedges or other structures.
Once calves are on pasture, they are exposed to parasites such as worms and coccidia. Coccidia generally don’t cause problems unless animals are stressed. Weaning off milk is a stressful event that often precipitates clinical signs.
Coccidia survive well in mud, so move meal feeders around the paddock regularly to minimise exposure, and use a meal that contains a coccidiostat.
Each calf should be eating 1kg of meal before weaning off milk.
Worms can potentially cause problems from 3 weeks after the calves start eating grass, so ensure you have a good drench programme in place.