Supplementing Your Sheep's Diet with Grain

When the pasture is not enough - Feeding grain to supplement your animal’s diet

 Oats, wheat, barley and sorghum are often used for supplement feeding of sheep when pastures are not adequate to meet the animals' dietary requirements. Sheep will also need roughage in the form of hay, if edible dry grasses are not available in the paddocks. You can also feed your livestock commercially made feed cubes or pellets. Refer to the instructions for quantities to feed your animals.

Sheep requirements for supplementary feeding
When feeding oats:
Weaners- 2.2 kg per week each
Dry adult- 3 kg per week each
Six weeks prior to lambing- 3.8 kg per week each
Lactating ewe- 5.1 kg per week each

When feeding barley, wheat or sorghum:
Weaners- 1.8 kg per week each
Dry Adult- 2.4 kg per week each
Six weeks prior to lambing- 3 kg per week each
Lactating ewes- 4.2 kg per week each

Oats are the preferred grain to feed sheep and cattle as they are less likely to cause lactic acidosis- a process that can kill your stock. Introducing grain (or any new feed) must be done gradually to allow the rumen bacterial colonies to adapt to the changing environment and be able to process the food safely without making excessive lactic acid.




Feeding grain to ruminant animals

Ruminant animals possess a rumen and the rumen is used to break down the feed consumed by the animal into usable energy. This breakdown occurs through fermentation of the feed in the rumen. Ruminants ruminate, or ‘chew cud’, turning partially digested food over in their mouth and chewing it to further break it down before swallowing it again. Ruminants naturally eat grass and foliage, which may or may not contain some seed heads or grains. They do not naturally eat large amounts of grain and their rumens, or first stomaches, are not designed to manage large amounts of grain, unless the rumen has had time to adapt to the increase in grain and the rumen bacteria have adapted to break the grain down.

Ruminants need to be introduced to grains slowly as they are prone to develop a condition called grain poisoning, grain overload or lactic acidosis.

Grain poisoning occurs when an animal which is not accustomed to eating grain is given access to grain and eats more than the rumen bacteria can process safely. The rumen processes the feed that animals eat by fermenting the grains and grasses with the aid of bacteria present in the rumen. It is this fermentation process that releases the required energy from the feed and allows the animal to absorb this energy and use it in metabolic processes. How much fermentation occurs and at what rate is directly related to the type of feed the animal is eating and the colonies of bacteria present in the rumen.


How the ruminants stomach system works

Ruminants have a different digestive system to other animals. They possess a unique stomach system comprised of four parts. The first part is the rumen, the second the reticulum. These two parts really act as one and together usually hold about 10 litres of feed, although the rumen can hold up to 20 litres if full to capacity. The rumen is rarely full to capacity. The rumen and reticulum are used to ferment the grasses and roughage the animal consumes. It is designed to hold food a long time because the food a ruminant would naturally eat takes a long time to break down into digestible matter. The bacteria that live in the rumen reticulum are specialists in breaking down cellulose, or plant material. They do this by the process of fermentation. The animal assists the process of digestion by regurgitating the food in the rumen and ruminating it, or rechewing it. The animal is able to do this because the less digested food consists of partially digested grasses and roughage and easily floats on top of the more digested food which has turned to a liquid. The animal can therefore regurgitate just the top layer of food.

.The third part of the stomach is the omasum and the fourth part the abomasum. The omasum is used to absorb the excess fluid from the rumen contents before they are moved on to the abomasums. The abomasums is similar to the stomachs of non ruminant animals, similar to human stomachs. Here any protein that has not been broken down by the rumen is broken down and any bacteria from the rumen are killed off by the highly acidic environment found in the abomasum. The rest of the ruminant’s digestive system is similar to ours, consisting of duodenum, small intestine and large intestine.

When a ruminant is born its rumen is essentially non functional. The mother will lick around her lamb’s face and mouth and this helps introduces the necessary rumen bacteria into the baby’s rumen. Early introduction to solid food (grasses) will encourage rumen development. The fermentation process started off by early solid consumption will then promote further rumen development. By the age of three weeks, a ruminant’s rumen should be well developed and able to effectively convert solid food to energy.

The important stuff: How the rumen bacteria work

Ruminants eat grass and other feeds, chew the food just enough to saturate it with saliva and then swallow it to the rumen. They will then regurgitate this semi chewed food and ruminate over it- rechew it and break it down into smaller parts to aid digestion in the rumen. When the feed is further broken down by the animal’s rumination, it allows greater surface area for the rumen bacteria to act on in order to ferment the rumen contents.

There are many different species of bacteria, in populations numbering billions, in a healthy rumen. The most common ones are called cellulolytic bacteria because they specialize in the digestion of cellulose. Cellulose is the major component of plants and is basically composed of glucose molecules held together in long chains. These chains give the plant its structure and shape. These bacteria break up these chains into individual glucose molecules by the process of fermentation. This breaking down of the cellulose into single glucose molecules releases energy that the bacteria use (in the form of ammonia) and also the ruminant uses (in the form of volatile fatty acids). The volatile fatty acids are absorbed across the lining of the rumen wall and absorbed into the animal’s blood stream. This is the major form of energy used by animals for their metabolic requirements (growth, heat production, organ function etc). Other by products of fermentation in the rumen include methane production and carbon dioxide production. These gases must be released by belching. A sheep will belch around 100 litres of these gases each day.
Other bacterial species present in the rumen can break down the starches (sugars) found in plants. Grasses do not contain a lot of starch, but their seeds do contain starch. The bacteria that break down starches are normally found in lower numbers in the rumen since ruminants are not naturally starch eaters- they normally eat grasses that do not contain a great amount of seed. If the animal is fed an excessive amount of starch containing grain, these bacteria use the starch to reproduce rapidly and an imbalance in the normal ratio of these bacteria occurs. These starch loving bacteria produce lactic acid as a waste product, much like we produce urine and faeces as our waste products.

 Finally another type of bacteria ( the one that helps prevent lactic acidosis in your animals) also lives in the animal’s rumen.  This bacteria is able to use the lactic acid as a food source and in the process convert the lactic acid into volatile fatty acids- the energy source that is easily absorbed across the rumen and which the animal uses as its main energy source. However, these bacteria exist in low numbers under normal grass grazing conditions, because as I said previously, in normal grass grazing conditions very little starch is eaten. It takes time for this population of bacteria to adapt to the newly increased amounts of lactic acid present in the rumen (lactic acid produced by the grain feeding bacteria after grain is introduced into the animal's diet), use the increased food source (lactic acid) to reproduce and increase their numbers. Once they have increased in numbers to meet the new increase in lactic acid, they are able to convert the lactic acid to fatty acids and therefore help keep the pH in the rumen above 5.5.Once the pH level in the rumen drops below 5.5, the rumen is considered acidic and the lining of the rumen is susceptible to damage and stripping from the new acidic environment. A ruminant has bicarbonate in its saliva as a protective mechanism against acid increases in the rumen. Your animal will try to produce excess saliva to help neutralise the acidity, but this mechanism will not be effective if the acidity is lowered rapidly and dramatically.

Lactic acidosis
When grain is fed in sudden high amounts the newly expanding population of starch loving bacteria are able to reproduce rapidly because of their new food source and they will excrete excess lactic acid as a waste product. This lactic acid will cause lactic acidosis. The excess lactic acid will encourage the lactic acid loving bacteria to reproduce and then their population will expand and these bacteria will convert the lactic acid to fatty acids and effectively help prevent the rumen pH getting too acidic. However, the lactic acid has to be present in the first place for the lactic acid loving bacteria population to expand enough to start reducing the lactic acid concentration in the rumen. The time between the build up of the lactic acid by the starch loving bacteria and the reduction of the lactic acid by the lactic acid loving bacteria is where the damage is done to the animal’s rumen. This is when the rumen pH drops and becomes acidic and the rumen wall is damaged by the acid. This damage can be permanent and have lifetime ill effects on the animal’s ability to absorb nutrition from food and therefore its long term health
The inside surface of the rumen is not protected by a protective mucus lining like our stomachs. Even brief increases in the acidity in the rumen will cause inflammation of the rumen lining, and very likely ulceration of the lining which can result in permanent scarring. These ulcers on the rumen lining can easily become infected and  these infections can pass from the rumen, through the lining and into the blood stream.  These infections, once in the blood stream can travel to other organs in the animal’s body and cause infection there. The consequences are very serious to the animal’s health and potentially fatal.

Epic Fail (or, Here’s what we did wrong and ended up dealing with a case of lactic acidosis):
I was given an orphaned lamb from a neighbour who we had become friendly with. She had found the lamb abandoned in the sheep sale yards and decided to save her life- an admirable thing to do. We named her Ruby Soho and she joined our other orphaned lamb at the time, Scout. These were my 2^nd and 3^rd lambs ever joining Enoch on a list that the following year would grow exponentially. Scout loved her bottle but Ruby was not as keen. She was more nervous than Scout and would only drink small amounts and quite reluctantly. Our farmer friend thought Ruby was about a month old, old enough to be put on solid food fully, so I decided to continue with the small bottle feeds but get her onto something more substantial as well. The lambs were in the back garden and had access to lots of good grass. I thought this would be enough, but my friend assured me it would not. She bought over a bag of crushed barley and said “keep a bucket of that out all the time and let the lambs take what they need. Barley is good for them.” I knew that giving grain to sheep had its problems and asked about that, but was reassured that the lambs would only eat a little, that crushing the barley prevented it from swelling up in the stomach (apparently the reason why sheep get grain poisoning according to my friend!), and that barley was the best grain to feed lambs as it was full of all the nutrients they needed.  So I did- without checking any other source to see if this information was actually correct! This was my mistake- never simply take another person’s advice without researching further into it. People get things wrong all the time! Even people who have been farming for many years and who you trust to know what they are doing!

So Ruby decided that she just loved the barley and ate so much she developed lactic acidosis. Hardly surprising since barley is the most likely grain to cause lactic acidosis and any grain that is crushed releases more of its starches that are the main cause of lactic acidosis. So the combination of the crushing and the barley couldn’t have been worse! I saw Ruby lying down and looking very unwell, having developed a restlessness, lack of co-ordination, appeared to be in pain, teeth grinding and muscle twitching, and watery scours and I referred to the internet, where I was surprised to read about the perils of feeding your sheep crushed barley. I also came across a potential remedy- the bicarb of soda drink.  We did give Ruby  bicarb of soda dissolved in a bottle of water, and she did recover, but I am not sure if her recover was spontaneous or because of the bicarb. However, I would try it again if the situation recurred.

Enterotoxaemia (Over eating Disorder)
Another very serious effect of feeding high amounts of grain to an animal which is unaccustomed to eating it is the potential for the animal to develop enterotoxaemia, also called over eating disorder. The rumen normally does not contain enough starch loving bacteria to breakdown the starch in the grain. The undigested starch therefore is passed out of the rumen into the intestines, where a particularly problematic intestinal bacteria, called Clostridium perfringens, which usually exists in small numbers in the intestine use the undigested starch as a food source and these bacteria proliferate. Clostridium perfringens proliferation causes severe gastric disturbance, blood poisoning, and death in young ruminants. Clostridium perfringens produce a toxin that is responsible for severe intestinal damage. Some young animals may die before any signs are observed.  Some young animals may stop feeding, appearing listless and become much less active, possibly lying down and not rising. Diarrhoea is a common sign, and death usually occurs quickly, within days of onset. However death may occur rapidly and dramatically within a few hours of onset of signs of acute diarrhoea, excruciating abdominal pain, rolling about in an effort to relieve the pain, kicking at stomach, convulsions, and strange posturing where the animal becomes rigid and arches or stretches its back and neck. The animal appears to be in severe distress and it is in severe distress. This is a terrible way to die.

Enterotoxaemia can be caused by overeating any food, including milk or formula. It occurs any time the rumen is unable to properly breakdown the starches in food and these starches pass unprocessed into the intestine. It is not only caused by feeding sudden large amounts of grain. Animals can be vaccinated against enterotoxaemia. Usually the mother is vaccinated when she is in lamb and the protection from the vaccine is passed on to the offspring across the placenta. This is the best way to prevent this disease. However if the mother was not vaccinated or you are unsure if the mother was vaccinated, the young animal can be vaccinated at 2 weeks old and again a month later. Any earlier than two weeks can mean the vaccine is rendered ineffective.

When the 17 orphaned lambs arrived on our farm I was struggling to feed them with the conventional baby's bottles and small soft drink bottles with teat attached. It was extremely time consuming! My neighbour friend ( the same one who was so confident that the crushed barley was so good for my lambs) bought over a lamb bar- a large bucket with several teats attached to the outside- which meant that many lambs could be fed at once. I was unsure of this, as I like to know how much each lamb is drinking to be sure it is getting enough milk, but I tried it out, under her insistence. We only tried it once. One of the lambs was so weak he just couldn't be bothered eating. I had to hand feed him or he would not have fed himself at all. He died anyway a few days later- he got to us too late to save. Another of the lambs was a glutton and was pumping the teat for so long I had to take him off. My neighbour friend insisted that he would stop eating when he was full. I disagreed and removed him from the lamb bar. I had, however, removed him too late and hours later he was rolling around in agony, kicking, convulsing and arching his neck and died an hour later. That is the unfortunate way that I discovered overeating disorder! I also realised that my farmer friend was quite the idiot and actually knew very little about farming and farm animal care.

Other problems

Other effects of grain overload are lameness and destruction of hoof tissue caused by toxins released in to the blood stream clogging up small veins of the hoof and causing ischaemia, or tissue death. Finally a frothy foam can develop in the rumen if it becomes less active and the churning is reduced or stopped because of grain overload. As a result of the excess abnormal fermentation, and the gastric stasis  the gases normally released by belching (carbon dioxide and methane) are trapped in the foam and cause the rumen to expand and bloat. This expanded rumen can apply pressure to the animal’s lungs and impair the animal’s ability to breath. The animal may even suffocate.

Remember- It takes only one episode of grain poisoning to have a potential life time effect on an animal’s health and well being. If the episode causes damage to the rumen lining it will impair the animal’s ability to absorb nutrients across the lining. The animal will suffer a lifelong inability to properly convert feed to energy and may be underweight and size for its age for its entire life. An undernourished animal is also more susceptible to illness and disease.


Prevention is the best cure.