Tips for preventing calf bloat in automatic milk feeding systems

Performance and weight gain can be set back if a calf suffers bloat and, as the condition is more common in automatic feeding than conventional, it is important in these systems to get everything right from hygiene to feed concentration to prevent cases.

Bloat occurs when the calf’s rumen or abomasum over-expands after the gas produced by microbes during the normal fermentation of feed builds up and gets trapped. In calves up to 10 days of age, bloat occurs in the abomasum but in older calves it can occur in either the abomasum or the rumen.

The exact causes of bloat are not fully understood, but it is commonly believed to be the result of the proliferation of opportunistic bugs such as clostridia releasing gas too quickly for the calf to process.

There are several risk factors including poor colostrum management and hygiene, immunity levels, changeable weather, scour and pneumonia, and calves that are premature or born after a short gestation are also more prone.

Bloat is more common in calves on automatic feeders than in conventional teat feeder systems, particularly those born in batch calving systems where many calves share a feeder at one time.

Many of the risks can go unnoticed so, even if a rearer believes the risk factors might not apply to them, it is worth investigating.

With automatic feeding, many calves share one teat and, although many machines have teat washers, they are not necessarily fool proof therefore disease transmission is still greater than in conventional systems, either for individual or group feeding.

With high numbers of calves sharing a single teat, it may mean that many have to queue when they are hungry, or are bullied when having their feed. This stress can alter their immunity and ability to digest feed.

Logistics at the feed station, which is commonly overlooked, can lead to many problems. With smaller breeds for example, if the teat is positioned too high it can affect the calf’s ability to close its oesophageal groove, the mechanism that allows the milk to bypass the rumen. The same can be true if the milk is flowing too quickly for the calves to drink – for example when openings are 4mm or larger instead of small or cross-shaped.

Automatic feeders are set to feed and wash at certain times and calves mostly adapt to the routine, but inconsistencies are still inevitable. Some feeders allocate feed in specific time slots therefore if a calf misses one of these, even by a minute, they may end up with less feed for that day but return to the same volume the following day. With their digestive system constantly adjusting it will become stressed and this can result in bloat.

Bullying at the feeding station often goes unnoticed. Calves can ‘steal’ feeds much more easily than we might believe so although the feeder will inform the rearer that a calf is getting a feed it has in fact been taken by another calf. This means two calves will have had inaccurate and inconsistent feeds.

Double checking the feed concentration is important to ensure that the feeder is mixing at the level that appears on the screen and that it is consistent because inconsistent levels of feed can predispose the calf to bloat.

A refractometer is a simple and effective tool for checking this. Check several times at the beginning of the rearing period and intermittently throughout.

Monitor the water pressure, especially to compare peak water usage – usually during and after milking – and during off-peak periods, to ensure the readings are consistent with each other.

Create a feed plan that suits your calves, rather than another farmer’s calves.

Within that plan, volume and feeding frequency can predispose the calf to stress and therefore bloat. It is important that a calf is satisfied with the feed so they don’t feel constantly hungry. For example, calves may be allocated six litres of milk at 12.5% broken up into four feeds which means a calf will be allocated a maximum of 1.5 litres per feed. The calf will never be satisfied and so will always be hungry. Allocating three feeds a day is a good place to start as this helps calves fall into a routine where meals are evenly spaced, queues are minimal and the possibility of animals having a completely empty stomach are reduced.

Another important factor is how the milk is mixed as every feeder differs – the type of milk replacer used is also a factor. If the feeder is over- or under mixing, the calf won’t receive all the ingredients. For example, an easy mixing milk replacer which is mixed for 30 seconds, combined with pumping through to stations, can turn into butter therefore the calf will lose out on this and it will make the feeder difficult to clean. A milk replacer which mixes poorly may settle quickly after feeding and block the feeder.

Applying additives to the calf feed can cause issues. It is important to check both the additives’ ingredients and the instructions to ensure it is compatible with the milk replacer and how the machine mixes. In some cases the milk may curdle in the mixing bowl.