Evaluate Feed Quality 

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The quality of feed refers to its ability to provide for the nutritional needs of the animal and is measured directly by calculating the amount of feed-in kilograms given to the animal and its growth in production.

The quality of a feedstuff is determined by:

• The freshness thereof
• The form in which it is given to the animal
• Degree of contamination of the feedstuff
• The number of digestible nutrients within the feed
• The correct balance between concentrate and roughage.

To assess the quality of a feed it is important not only to physically assess the feed but also to make sure that none of its ingredients can be harmful to the animal.

Where animals are fed it is important to carefully monitor the feed in the troughs:

• Make sure there is always fresh feed in the troughs as most animals in feedlots can afford to feed very selectively.
• The feed should be provided at regular intervals and in amounts that can be finished in a relatively short period of time. Production improves drastically when large amounts of feed are divided and given at regular intervals.
• All leftover feed must be removed at the end of each day.
• Remove all foreign materials from the troughs as this may block the animal's digestive system.
• Troughs should regularly be disinfected to prevent the spreading of disease.
• Troughs should be well-positioned out of the elements to protect feed from rain. Some feeds like urea may become poisonous when it gets wet.

To ascertain that specific ingredients or feed blends meet those criteria we have to take samples of those feeds or ingredients that must be tested. In all cases, at least 10% of the packages should be sampled. A minimum of approximately 1kg should be collected from each load. All cores should be combined in an airtight container.

When assessing the quality of samples, we first have to identify the areas that can be tested to determine the quality of the tested samples. The following table gives a few examples of the test that can be conducted on feed blends and ingredients. These tests can be quantified, in other words, the results can be counted to give the feed blend or ingredient a quality rating.

Physical Evaluation of Feed Quality

A physical evaluation is easy but rough in nature. One must be highly trained to identify the changes in the nature of the raw materials/feeds. Usually, the following criteria are investigated:

Colour: The appearance of the ingredient will reveal its quality. Any change in the colour of the feed ingredients gives an indication of the maturity of the grain, storage conditions, presence of toxins, contamination due to sand, possible use of insecticides/fungicides which gives a dull and dusty appearance. The Orange to red colour of sorghum indicates high tannin content. Browning or blackening due to heat on improper storage reduces nutritive value. Black coloured fish meal indicates the rancidity of fish oils.

Size: The size of the grains governs their energy value due to the proportion decrease/increase in seed and its coat. The smaller the grain lower will be the protein value in proportion to the hulls. To evaluate the cereal's weight of a fixed number of grains usually 100 grains or fixed volume is taken. Higher weight indicates a higher protein value. This technique is called Test Weight.

Homogeneity: The presence of contaminants like other grains, husks broken grains, weed seeds, infested seeds is looked for. In the oilseed cakes, closer observation will reveal the presence of fibrous material, especially in de-oiled groundnut cake, the cake with hulls that contains nearly 20 to 25 % crude fibre can be visually identified. Clumps in mineral ingredients make them unsuitable for premixing.

Smell: Smell is the next best indicator just standing near the stock itself will immediately indicate any difference in the normal smell. The feedlot manager should familiarise himself with the normal smell of the ingredients, any change in the normal smell of the ingredients should be viewed with suspicion. A musty odour indicates the beginning of fungal contamination or boring insects. To detect rancidity in oil-rich feed ingredients this is the best method. An odour of petroleum products is suggestive of excessive pesticide or fungicides. A leathery smell of meat indicates adulteration with the leather meals.

Taste: Each ingredient has a different taste, any change in the taste like bitterness in the grains, soya, sunflower oil meal and groundnut cake might indicate the presence of mycotoxins. The level of salt can be detected by tasting the ingredient and the feed. The bitter taste of rice polish indicates the rancidity of the fatty acids.

Touch: Feeling the raw material will indicate dryness. Chilliness indicates high moisture content. Clumps can be found by inserting the hand inside the bag. The clumps may be due to high moisture content, improper storage, packing of fresh warm solvent extracted from the meal, which crumbles on the application of light pressure. Clumps formed due to excess of moisture will be very hard. To evaluate rice polish, place about 25g of rice polish on the palm and close the fingers tightly and then open the fingers, the rice polish will become like a solid mass if the crude fibre level is below 12% if the fibre level is high the mass will disintegrate once the fingers are opened. Further pressure will be felt when the hand is closed in high fibre rice polish.

Sound: Dry grains pouring down orbiting will produce the sound of spilling coins.

The detection of adulteration or contamination: The common contamination or adulteration in most ingredients is husk or sand. Winnowing is the best method to detect husk in feedstuff. Sieving can be done to differentiate contaminants based on particle size. To detect the presence of sand a weighed quantity of the grain is soaked in water then by sieving with hand the grains that be separated. The remaining water if decanted the settled sand can be weighed and the level of contamination can be assessed.

Chemical Evaluation of Feed Quality

An analytical laboratory for the precise estimation of nutrient contents and contaminants is of utmost importance. Analyse the feeds for proximate principles. This indicates possible constraints on usage due to the presence of excessive content of crude fibre, fat or total ash. Low crude protein and high crude fibre (CF) levels of oilseed meals are indicative of adulteration with fibrous material. The high CF alone is indicative of adulteration with urea and or some inferior quality oilseed meals.

The amount of acid-insoluble ash is a good guide to the amount of sand or other dirt which may be present. Fish meals are usually adulterated with sand during the drying process.

It is also desirable to determine the free fatty acid content of oily materials as this will affect palatability due to the rancidity of oils. The chemical composition or specifications of various animal feeds are laid down, which acts as guidelines for the suppliers, buyers and users at the farm level. Protein meals should also be analysed for their amino acid contents.

Ingredient specifications are essential in a feed quality assurance program. Specifications serve as the basis from which purchasing agreements are written, feed blends are formulated and ingredient inspections are performed.

Ingredient description and general nutritional specifications may be found in specifications for feeds and feed ingredients. Specifications of feeds must be as comprehensive as possible, realistic, must be transmitted to the seller. These are the measuring sticks to which the delivered material must conform.

Specifications are the foundation of a quality assurance program because they serve as an understanding between a nutritionist, purchasing and production departments. A list of feed ingredients and their target nutrient level is presented as an example. Some analytical procedures are given to detect the various types of adulteration.

Toxins in Animal Feed:

Ultraviolet screening is used whereby a greenish-yellow fluorescence is observed when the sample is exposed to ultraviolet light to detect mycotoxins. One should get the best source of supply and one should have some idea of normal levels of toxicity that may be expected.

Biological Evaluation of Feed Quality

Biological evaluations of feeds involve the use of animals and specialised persons to conduct the digestion and metabolism trails on the various species of livestock. These methods are time-consuming.

Another important factor that is used when assessing feed is the heat discharge factor. Heat discharge is commonplace and takes place when the moisture content of ingredients is too high. A high moisture level in ingredients usually leads to fermentation of those ingredients and a by-product of the fermentation process is the release of heat.

Whilst feed and ingredients have been assessed the presence of heat should be immediately reported to the feedlot manager or operator as this might be an indication that the feed is not suitable for use. It is always good practice to ensure that all staff involved in the mixing and distribution process of the feed should be trained to look for heat discharge in the feed and report it when found.

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