How feeds poison cattle

As promised recently, today I will explain how the wrong choice of feeds and feeding cattle poisons your animals slowly. The full impact of the poisoning usually becomes evident when pregnant animals calve down. The post-mortem findings are unimaginable to the untrained mind. Some farmers have even called the subacute ruminal acidosis (SARA) damage in the cow’s body an act of the occult.

Signs of sickness 
The truth of the matter is that animals with SARA will always show signs of sickness. The signs are subtle and the internal damage occurs gradually with increasing severity and magnitude until the vital body organs are overwhelmed.

These are mainly the rumen, liver, heart, lungs and kidneys.

SARA is different from acute rumen acidosis (ARA). ARA is seen when cattle are fed a high carbohydrate diet at one feeding either by error or when the animals inadvertently come across such feeds.

Dangers of feeding your animals with waste feeds 
I was called to attend to my first case of ARA when a wedding was poorly attended and the left over bread and rice were fed to the cows of the groom’s father. The following morning, all the 10 Friesians had gone off feed, were dull and just kept drinking water. ARA happens quickly; it is easy to observe that the animals are sick and the situation keeps deteriorating fast if not attended to.

SARA, on the other hand, occurs slowly and all animals may recover if the diet is changed before the major body organs are too damaged. Unlike ARA, SARA may be absolute or relative. The absolute form is caused by a feed that is badly formulated with too much carbohydrate and too little roughage. Carbohydrate in animal feeds is called energy. It is provided by starchy or sugary feed materials such as grains, cassava, fruits, potatoes, silage and other products of these materials.

Importance of roughage 
Roughage is termed as fibre in animal feeds lingo. It is mainly supplied by grass as fresh or hay. It may also be obtained from other plant materials such as wheat, rice or maize residues after the produce is harvested.

Relative SARA is seen when the feed is well-formulated but the preparation and mixing is defective. For a cattle on total mixed ration (TMR), the right quantities of each feed ingredient should be determined using a formula designed by an animal nutritionist. The ingredients should then be weighed individually. The fibre component should be chopped to pieces of about 4mm long.

To the naked eye, that looks more like a powder than actual grass. It has been determined scientifically that fibre length of 4 mm mixes well with the energy and protein components of the TMR to produce a feed of uniform texture. When that mixture is fed to cattle, they are able to take direct bites of the feed without sorting out the energy particles first.

Energy feed component
By nature, the energy feed component is more palatable to the cow than the fibre. Therefore, if the fibre chopping is longer than 4mm, the TMR does not mix well and the cows are able to first search out and eat the smaller energy and protein particles of the feed. This is called sorting feeding behaviour. When a farmer observes sorting behaviour, they should review the chop-size of their fibre.

Cows do not eat large quantities of feed at once. They need to leave enough room in the rumen to facilitate contraction of the organ and regurgitation of the feed, otherwise called rumination or chewing of the cud. They will thus first leave the long fibre untouched and eat it later.

Having eaten the energy and protein particles first in the sorting behaviour, the cow will already be containing too much carbohydrate in the rumen. Carbohydrate and protein diet components are not regurgitated. The carbohydrates are broken down to produce lactic acid.

Fibre 
The fibre in the cattle diet stimulates regurgitation and heavy saliva production. A normal cow produces about 60 litres of saliva per day. The fluid is used to neutralise lactic acid in the rumen and maintain a close to neutral pH. pH is the scientific measure for acidity.

When fibre is low in the diet, regurgitation fails and the rumen becomes acidic.

Cattle with feed sorting behaviour will have periods of high rumen acidity of about four to five hours before they get back to the trough and eat the fibre feed component they left. By that time, the rumen is already inflamed by the lactic acid and the animals’ appetite goes down.

A farmer will observe that their animals will eat lazily and increasingly take longer to finish their rations completely.

Once the cows eat sufficient fibre, the rumen regurgitation resumes and the cows are again seen chewing the cud. This deceptive behaviour prevents the farmer from noticing that all is not well with her animals.

The swings between rumen acidity and neutral pH cause ulcers in the rumen. In extreme cases, the ulcers may perforate through the wall of the rumen and cause massive infection of the abdominal cavity. Even when the ulcers do not perforate, bacteria and toxins easily pass into the body and cause infection and rotting in the major body organs. To prevent SARA, farmers should ensure the feed is properly formulated, prepared and mixed to produce a meal of uniform texture that the cow can eat in uniform bites without sorting.

Roughage 
Roughage is termed as fibre in animal feeds lingo. It is mainly supplied by grass as fresh or hay. It may also be obtained from other plant materials such as wheat, rice or maize residues after the produce is harvested.