Maximising meat yield and optimal fat cover for finishing beef cattle is all about providing sufficient energy and starch. But this needs to be achieved without upsetting rumen stability. This means finishing rations must be balanced and fed correctly to prevent issues such as acidosis occurring.
What is rumen acidosis?
There are two types of rumen acidosis, acute ruminal acidosis which is more common in finishing cattle and subacute ruminal acidosis (SARA) which is more common in dairy cows. Read more about formulating autumn diary diets to prevent SARA here.
Effect of acidosis
Ruminal acidosis is a metabolic disease caused by prolonged periods of changes in rumen pH from the optimum range, between 6.5 to 7.0 (the ideal conditions for fibre-degrading bacteria), to 5.5 or less.
The fall in rumen pH causes rumen movement to reduce or stop completely. This depresses appetite, reducing feed conversion efficiency subsequently impacting daily live weight gain targets. This means cattle that recover from acidosis may not reach their target finishing weight or take longer to do so.
The balance of the rumen micro-flora is also affected by the change in pH, increasing acid producing bacteria. The acid can damage the rumen epithelium, causing metabolic acidosis, which can lead to shock or death within 24-48 hours in severe cases.
Liver abscesses can develop secondarily to acidosis which can increase the risk of further health issues. Laminitis can also occur, making it painful for cattle to stand, reducing feed intakes further.
Causes of acidosis in cattle
Finishing rations for beef cattle typically contain a high level of rapidly fermentable carbohydrates (such as barley, wheat or concentrates) which are the primary cause of acidosis if:
- Cattle are suddenly transitioned from grazing or high forage diets on to the finishing diet
- Cattle ingest large amounts of cereals or a diet high in concentrates in a short period of time
- Insufficient fibre is fed to accompany the rapidly fermentable carbohydrate rich feed
The clinical signs of acidosis will be presented more quickly if the grain fed is milled or ground, as opposed to whole, because it is fermented faster which increases digestibility.
Symptoms of ruminal acidosis
Not all cattle affected by acidosis will show symptoms. However, common signs include:
- An enlarged rumen and abdominal pain indicated by belly kicking or tail swishing soon after eating.
- Cattle may gorge on water after consuming large amounts of cereals or concentrates but stop drinking as the condition worsens
- Dung may be loose or soft, grey and foamy. It may also contain gas bubbles and undigested feed and have a sweet-sour smell
- Poor rumination/cudding rates and/or poor appetite
- 24-48 hours after severe engorgement, cattle may appear weak, lethargic or have difficulty moving
- Signs of more severe acidosis include a decreased heart rate and an increase in temperature. Some cattle may appear to improve temporarily before becoming severely ill once again
Preventing rumen acidosis in finishing beef cattle
There are simple feed management protocols you can follow that will help prevent acidosis occurring. These include:
- Make any diet changes over a two-to-three-week period to allow rumen microbial populations to transition from predominantly fibre digesters to predominantly starch digesters. Top Tip: You can achieve this by incorporating 3kg/head/day of concentrate or cereals into the ration and stepping this up by 1 kg every 3 days. Monitor for digestive disturbances as you do, until you have reached the desired maximum feeding level
- Ensure there is a supply of roughage, preferably wheat straw, to encourage rumination. Hay or haylage is more likely to substitute concentrate intake and reduce performance. Straw should ideally be chopped between 2-4 inches to minimise sorting.
- Consider adding a live yeast into the total mixed ration (TMR) or use a feed formulated to include a live yeast. This can help prevent dietary upset when transitioning to higher-energy rations because the live yeast helps to stabilise rumen pH.
- Feed concentrates and cereals ad lib or in small meals, to prevent gorging.
- Ensure there is adequate feed space to allow cattle access at all times to reduce competition and gorging.
- Make sure clean water is available at all times. Finishing cattle can require as much as 80 litres of water/head/day.
- Ensure finishing diets are formulated correctly and keep them as consistent as possible once they are. Consult your local Carr’s Billington on-farm specialist if you require advice or assistance.
You may need to consult your vet for advice if you need assistance with treating acidosis or the secondary issues it can cause.