2.3.4. Quality Control
The enormous variation in the composition of raw materials
requires quality control
- on receipt of raw materials;
- on manufacture
of the feed.
Quality control of raw materials received
Quality control of materials is necessary in order to calculate
precisely the properties of the feed which must satisfy the nutritional
requirements of the stock to ensure optimum productivity. Such control is
effected by means of a laboratory with the appropriate equipment and reagents
for analysis. The latter is conducted in accordance with internationally
recognised methods so that the results of one laboratory may, if necessary (for
instance in the event of a dispute), be checked by another; this would make no
sense if the methods used were not strictly identical. There are EU regulations
covering methods of analysis for animal feedstuffs.
Analytic procedures may be divided into four categories:
- Routine analysis: humidity crude protein
fats, cellulose, mineral substances, insoluble in HCl.
- Conventional analysis: calcium, phosphorous, chlorides.
- Special analysis: magnesium, sodium, potassium,
oxidation of fats, cell-wall components, trace elements (iron, copper, cobalt,
zinc, manganese, iodine), aflatoxins, gossypol, cyanides, available lysine, etc.
- Investigation tests: amino acids, fatty acids,
vitamins, toxins, etc.
These are in fact chemical tests requiring specific techniques
in which the complexity of the equipment and the necessary skill level increase
as one moves from routine to investigation tests.
This is why, in practice, a regional or sub-regional laboratory
which can legitimately conduct quality control through routine analysis is a
very important first step in improving feed quality. Near infra-red spectrometry
is a recent technique which enables the composition of raw materials and
finished products to be determined precisely in a few minutes.
As the analysis is conducted only on a sample of a few
dozen grams, the latter must be representative of the lot from which it comes.
This is why sampling must be conducted with care. One should preferably use a
probe to take samples from various places in the lot; these will then be mixed
together roughly and a sample taken for the laboratory.
The laboratory results will be sent to the nutritionist
responsible for formulation, who will use them to establish the various formulas
to be manufactured. Software is currently available to calculate feed formulas,
bearing in mind the individual characteristics of each of the raw materials and
their cost, as well as the nutritional constraints imposed by the nutritionist.
CHOICE OF FEED MILL
· DEFINING THE TONNAGE TO BE
· SIMPLE, ROBUST
· VARIOUS OPTIONS: ADDITION
OF MOLASSES, PELLETING, ETC TO BE LOOKED AT CAREFULLY
· ASSISTANCE FROM SUPPLIER
(ASSEMBLY, COMMISSIONING, SPARE PARTS ETC)
It goes without saying that this most valuable and efficient
tool will not provide useful solutions unless the information provided is itself
reliable, hence the necessity for continuous verification of the data used in
calculating the formulas.
Quality control of manufactured feed
The manufactured feed is checked to ensure that its properties
are in accordance with those calculated by the nutritionist. Manufacturing
errors can thus be detected if there are inadmissible discrepancies. The
manufacturer will have a record of the analyses of the manufactured feed which
he can go through in the event of a dispute.
It is worth pointing out that while chemical analysis is a
precious aid in manufacturing quality feed, it is no less true that it is not
sufficient in itself. The appearance of the raw material also plays an
important part in appreciating quality.
Sometimes, a simple visual, olfactory or organoleptic
examination suffices to assess the sanitary status of a raw material (presence
of weevils, cockroaches, worms, putrid or fetid smells, musty, sulphurous or
rancid smells, abnormal colouring and so on are all indicators which might lead
to a suspicion of defective quality).
The preliminary examinations can then be confirmed by
microscopic, bacteriological or even chemical examination by a specialist