Feeding your Pets 

Feeding animals is easy, but giving them the type and quantity of food that will sustain good health can be another thing altogether. 

Consider the digestibility of the various foods that are used in farming. We have seen how food is broken down and digested; we will now consider how much of this food is digested. In animals with a simple stomach (this includes man) most of the food that is eaten is digested, mainly because the food itself is highly digestible.

Animals, such as pigs, are fed concentrate foods like cereals and these are fed as a finely ground meal which helps the animal to digest the food. In the case of man, the food that he eats is refined (e.g. white sugar and white flour) from which most of the indigestible roughage has been removed during the manufacturing process. Furthermore, unrefined food like meat, potatoes and vegetables are cooked before being eaten and this softens and breaks down the fibre and cellulose making digestion easier.

In the case of man, the feeding value or energy value of a food is measured in calories. The requirement of a man is 3000 calories a day while woman need 2200 calories. A calorie is the amount of heat or energy required to raise 1 gram of water by 1 degree C (remember that heat and energy are the same thing). The calorie system works well with man because the food he eats is highly digestible, either through being refined or cooked. Foods that are high in calories are said to be 'rich' foods and those low in calories are called 'roughage foods'.

When we come to consider the digestibility of foods in the ruminant animal, the story is very different because ruminants eat very bulky foods which are high in cellulose and lignin. Although the ruminant digestive system is designed to deal with bulky foods, the amount that is actually digested will depend on the food itself. Concentrate foods, especially those that are ground up before feeding, are highly digestible. Young grass is low in fibre and therefore easy to digest, some grasses at some times of the year are old and tough and have a low digestibility rating. The animal will eat the grass and it will satisfy it's appetite, but much of the fibre will not be broken down or digested - a lot of the grass will be passed out of the animal as dung.

Another point to remember when feeding animals is that the highly digestible concentrate foods are expensive, while the roughage foods with a low digestibility are much cheaper. This makes it important to have a good knowledge of the digestibility of the different foods when deciding what to feed the various kinds of animals.

Is it Digestible?

How is the digestibility of food worked out? It is a complicated business and requires a lot of chemical analysis, which has to be done in a laboratory. The principle, however, is fairly simple. The first step is to analyse the composition of the food stuff itself to find out what is contained in the food. Any animal food can be broken down into different components. There will usually be some water in any food; but the bulk will be commonly made up of protein, fats and oils, soluble carbohydrates, minerals, amides and fibre

Having worked out the analysis of any foodstuff, it is possible to find out the digestibility of that food for any type of animal. Suppose we want to know the digestibility of maize when it its eaten by rats! This would be done by putting a rat in a cage that was arranged so that the dung and urine from the rat could be collected each day. The rat would be fed maize meal that had been analysed and the dung and urine would be analysed in the same way.

At the end of the week, there would be enough results to see how much of the maize fed to the rat had been passed out as dung and urine (i.e. had not been digested). The remainder (the part that stayed inside the rat) would have obviously been digested. We would also be able to analyse the amount of each part of the maize that was not digested by the rat (thus learning how much protein, fat, fibre, minerals, and soluble carbohydrates had been digested).

By measuring and analysing the maize meal going into the rat and the dung and urine coming out, we can work out the amount of each part of the food that has been digested. If we express this as a percentage of the original food fed, we get what we call a Digestibility Coefficient for the protein, fat, carbohydrates, etc. in the maize meal.

The Digestibility Coefficients of the common feed stuffs have been worked out for any animal.
Digestibility is an important idea in animal feeding. By analysing the food, we know how much protein, fat, etc. that the food contains,. By using the digestibility coefficient for each part of that food, we can work how much protein, fat, etc from that fat WILL BE USED by the animal.



Distance Education Course (click here to enrol)



ANIMAL FEED AND NUTRITION (BAG202) (Formerly Animal Husbandry lll)

By studying this course you will develop a broad understanding of to the correct feeding of domestic animals (farm animals and pets) for health and productivity. Though focussed mainly on domesticated animals thew course is nevertheless still a valuable training opportunity for anyone involved in even care of wild animals.

Duration:100 hours (nominal duration)


There are ten lessons in this unit, as follows:
1.Introduction to Animal Foods
2.Food Components: Carbohydrates, Fats
3.Food Components: Proteins, Minerals.
4.Evaluating Foods & Digestibility
5.Classifying Foods: Part A.
6.Classifying Foods: Part B.
7.Classifying Foods: Part C.
8.Calculating Rations: Part A.
9.Calculating Rations: Part B.
10. Calculating Rations: Part C.
·Describe the range of livestock feeds and feeding methods available for animal production, using accepted industry terminology.
·Explain the role of energy foods, including the sources and functions of those foods, in animal diets.
·Explain the function of the major nutritional groups, including proteins, vitamins, minerals and trace elements in animal diets.
·Explain the on-farm methods used to evaluate feeding, including selection of feeds and feed digestibility.
·Evaluate the dietary value of pastures, including grasses, cereals, and other edible plants, and their by-products for animal feeds.
·Explain the dietary value of seeds, including oil seeds, legume seeds and their by-products as food sources for animals.
·Evaluate the dietary value of fodder plants, including trees and shrubs and their by-products, as a food source in animal production.
·Determine suitable feed rations for a farm animal maintenance program.
·Analyse the method(s) to determine suitable feed rations in a farm animal production program.
·Evaluate the dietary value of protein in an animal production program.
·Explain the factors affecting the composition of feed rations in animal production.
·Explain the importance of feed quality in livestock production.
·Describe the various food groups that animal foodstuffs are based upon.
·Define at least fifteen relevant industry terms related to livestock feed, feeding and feed processing.
·Explain the role of water in animal nutrition.
·Describe three different, commercially available, animal feeds, including the composition and appropriate uses for each.
·List the chemical names of at least five different carbohydrates which are of importance to animal production.
·Evaluate the roles of four different carbohydrates in animal metabolism.
·List the important sources of carbohydrates for at least four different types of farm animals.
·List the chemical names of at least five different fats which are important to animal production.
·Compare fat deposition patterns in three different animals.
·Explain the role of two different lipids in animal metabolism.
·List the important sources of fats and lipids used in livestock feeds.
·Explain the importance of proteins to animal production.
·Describe the chemical composition of naturally occurring proteins.
·List the sources of protein commonly used in foodstuffs for two different types of farm animal species.
·Explain the differences in protein requirements for different animals.
·List five vitamins of importance in livestock nutrition.
·List five minerals of importance in livestock nutrition, including their source foods, requirement levels, physiological functions, and deficiency symptoms.
·List five trace elements of importance in livestock nutrition, and including their source foods, requirement levels, physiological functions, and deficiency symptoms.
·Prepare a one page chart or table comparing the vitamin, mineral, protein and trace elements components of three different commercial animal feeds.
·Explain the function and source of the various nutritional components found in three different commercial livestock nutrient supplements.
·Describe the components of a specified animal feed.
·Distinguish between the 'protein value' and 'energy value' of two specified animal feeds.
·Explain the concept of 'digestibility' as it relates to animal feed.
·Describe the techniques used to calculate digestibility of animal feeds.
·Perform a calculation of digestibility for a specified feed.
·Describe two standard methods used to assess animal feeds.
·Compare five different feeds, in terms of composition, relative digestibility, palatability.
·List at least five cereal and cereal by-product feeds used in animal production.
·Describe the food value characteristics of five cereals and cereal by-product feeds used in animal production.
·List at least five grasses and forage crops used as farm animal feeds.
·Describe the dietary value of five forage crops, including grasses, used in animal production.
·List at least five harvested feed products, including hay, roughage and silage used as feeds in animal production.
·Explain the dietary value characteristics of five harvested feed products including hays, roughage and silage used in animal production.
·Explain the dietary value of a growing pasture, on a farm visited and studied by you.
·Compare the nutritional value to farm animals, of ten different pasture foodstuffs, including cereals, grasses, hay and their by-products.
·List four oil seeds (or their by-products) used as feeds in animal production.
·Explain the use of oil seeds (or their by-products) as animal feeds.
·List three legume seeds used as feeds in animal production.
·Evaluate the dietary value of three different legume seeds, as animal feeds.
·Collect small samples of three oil seeds and three legume seeds.
·Compare the characteristics of two different oil seed species, with two different legume seed species. List five fodder plants (or their by-products) used as feed in animal production.
·Provide recommendations on how three different fodder plant species may be used as an animal feed source on a specified farm.
·Compare the nutritional value of three different fodder plant species.
·Explain the objective of maintenance rationing in two different farm situations observed by you.
·Explain the differences in feed rations given to maintain the same type of animal on two separate farms.
·Describe the nutritional requirements of two different specified types of livestock.
·Calculate a 'maintenance feed ration' for a specified farm animal.
·Develop a maintenance feeding program, for a group of animals, such as a herd of cattle or flock of sheep. 

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