The accuracy of fodder analysis depends on the sample you send to the laboratory. It is critical that the sample represents the average composition of the “lot” of fodder sampled, otherwise the laboratory tests will not be useful.
A “lot” is defined as hay or silage taken from the same cutting, at the same stage of maturity, the same species (pure or mixed) and variety, the same paddock, and harvested within 48 hours. Other factors influencing the definition of a “lot” include rain damage, weed content, soil type, treatment after cutting and storage effects. A “lot” of baled hay or cubes should not exceed 200 tonnes.
Sampling hay
Representative hay samples can only be obtained with a probe or core sampling device. Do not rely on a couple of handfuls or a “flake” from one bale. HAYCORE sampling probes are commercially available in Australia from Tonwen Engineering ,(11-15 Port Fairy Road, Hamilton, Victoria 3300, phone Tony on 0355711843, or e-mail [email protected]) and there are several types also marketed in the USA. Alternatively, they can be home-made using 32 mm steel tubing, and should be at least 450 to 500 mm long with a slightly scalloped and sharp cutting edge. Corers are driven either using a hand brace or an electric drill (where practicable). Some cordless drills may not be suitable if they lack power or turn too fast. A portable generator is useful and can be justified if many samples are taken.
Small square bales
Sample between 10 and 20 small square bales, selected at random from the “lot”. Take one core from each bale selected, probing near the centre of the “butt” end, at right angles to the surface. Ensure that the corer does not get hot. Combine all cores into a single sample in a bucket, and mix thoroughly. The whole sample should be kept intact and not subdivided.
Large round or square bales
Sample between 5 and 10 large bales, again selected at random. Take one core from each side of all bales selected, probing at right angles to the surface at different heights. Combine all cores into a single sample in a bucket, and mix thoroughly. The whole sample should be kept intact and not subdivided.
Cubes or pellets
Select a handful of cubes or pellets from at least 6 locations or bags which make up the complete lot. Combine the sub-samples in a bucket and mix thoroughly to obtain a final sample not exceeding 500 grams.
Sampling silage
Silage is best sampled at least 3 weeks after it has been ensiled, and as close to the time of feeding as practicable. In theory, there should be minimal losses in quality if ensiled correctly, but in practice this is not always the case, depending on time of wilting, rain or heat damage, mould and the presence of air.
Pit or bunker silage
Before opening the pit or bunker, core samples for analysis can be obtained using a long coring device that extends into the full depth of the pit or bunker. Alternatively, random handfuls can be taken from at least 10 locations across a freshly cut face of the stack, although this will not provide such a good representative sample. Combine all the material into a single sample in a bucket and mix thoroughly to obtain a final sample not exceeding 500 grams, reducing the sample by the quartering process if necessary.
Wrapped baled silage
Sample between 5 and 10 large bales at random, using a coring device in the same manner as for large hay bales. However, this procedure is acceptable only if great care is taken to reseal the holes made in the plastic by the corer. Combine all cores into a single sample in a bucket, and mix thoroughly. The whole sample should be kept intact and not subdivided.
Sample handling
Immediately after sampling and mixing, the final fodder sample should be placed in a robust (preferably “press-seal”) plastic bag and tightly sealed to exclude as much air as possible. This is to ensure that the laboratory report of dry matter will approximate the dry matter content of the “lot” when it was sampled and any aerobic spoilage will be minimal.
Samples must be delivered to the laboratory as quickly as possible after being taken. In particular, silage samples must be frozen immediately after being taken, unless they can reach the laboratory on the same day they were collected. This is especially important during hot weather. Avoid mail delays over the weekend by posting samples early in the week.
Ensure that you closely follow the laboratory’s instructions for labelling samples and filling out all the required details on the sample submission sheet.
If you have any further queries or problems regarding sampling or sample handling, contact the appropriate AFIA-recommended laboratory for further information.