PHYSICAL EVALUATION OF FEED STUFF AND IDENTIFICATION OF MATERIAL

1. PHYSICAL EVALUATION OF FEED STUFF AND IDENTIFICATION OF MATERIAL

Introduction:

The physical evaluation of feed mostly provides preliminary information on the quality of the material. It involves assessing physical qualities such as weight, colour, smell and whether the material has suffered from any contamination by other materials.

Importance of Feed Evaluation

Feed evaluation is important because ingredients that belong to the same class contain different nutrients; for example, maize provides more energy than wheat while soybeans contain more proteins than lupins and canola. The same ingredient varies from one supplier to the other, and between years. In drought years, cereals fill poorly and are therefore lower in quality. Most importantly, if feeds are not evaluated, it is not possible to tell if the material will be suitable for feeding poultry. Feeding standards have already been set for different types of poultry, so the requirements for different nutrients must be met precisely. It is possible, with the current state of knowledge, to predict poultry growth or egg production by modelling feed quality, type of housing, class of poultry and duration of feeding. The central key issue in these models is feed quality, which can only be obtained through feed evaluation.

Following physical methods are adopted to evaluate the feed.

Colour

The appearance of the ingredient will reveal its quality. Any change in the colour of the feed

ingredients give an indication of the maturity of the grain, storage conditions, presence of toxins,

contamination due to sand, possible use of insecticides/ fungicides which gives dull and dusty

appearance. Orange to red colour of sorghum indicates high tannin content. Browning or

blackening due to heat on improper storage reduces nutritive value.

Size

Size of the grains governs its energy value due to the proportional decrease/increase in seed and

its coat. Smaller the grain, lower will be the metabolizable energy (ME) value due to more

proportion of coater hulls. To evaluate the cereals, weight of a fixed number of grains usually 100

grains or fixed volume is taken. Higher weight indicates a higher ME value. This is called Test weight

Homogeneity

The presence of contaminants like other grains, husk, broken grains, weed seeds, infected seeds is

viewed. In the oil seed cakes closer observation will reveal the presence of fibrous material,

especially in de-oiled groundnut cake. Rice polish is contaminated with husk. Clumps in mineral

ingredients are not suitable 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 plant manager should familiarize himself with the normal smell of the ingredients; any change in the normal smell of the ingredients should be viewed with suspicion. Musty odour indicates the beginning of fungal contamination or boring insects. To detect rancidity in oil rich feed ingredients this is the best method. Odor of petroleum products is suggestive of excessive pesticide or fungicides.

Touch

Feeling the raw material will indicate dryness. Chilliness indicates high moisture content. Clumps can be detected by inserting a hand inside the bag. Clumps may be formed due to high moisture content, improper storage, packing of fresh warm solvent extracted meal, which crumbles on application of light pressure.

Taste

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

Sound

Dry grains on pouring down or biting will produce sound of spilling coins