ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

PREPARATION OF SAMPLES OF HERBAGE, FAECES, URINE AND SILAGE FOR CHEMICAL ANALYSIS

• Biological materials are not homogenous in nature. Therefore, to obtain representative sample for analysis, systematic procedures have to be followed.
• The main objective of sampling is to draw small amount of a representative material from bulk quantity.

Preparation and proessing of sample of herbage, faeces, urine and silage for chemical analysis 

• Biological materials are not homogenous in nature. Therefore, to obtain representative sample for analysis, systematic procedures have to be followed. The main objective of sampling is to draw small amount of a representative material from bulk quantity.

Sampling of hay or straw

• A core sampler can be used for sampling baled or long hay after curing. Using the core sampler hay samples are collected in a random manner from 3-4 locations. After the sample is drawn, straw or hay or any other dry roughage should be chaffed (3-4 cm) and thoroughly mixed before sub-sampling.

 Photo showing core sampler

Sampling of green fodders

• Green fodders are collected from field or from bulk supply at various places randomly. They are cleaned of contaminants, chaffed (3-4 cm), mixed well and sampled.

Sub-sampling

• Sub-sampling of roughages is done using the following procedure.
• Make a conical pile of the chaffed roughage.
• Divide the pile into 4 or 6 parts.
• Randomly choose one part and its opposite part.
• Discard the rest. Repeat until a suitable sample size is obtained.

Sampling of silage

• Silage may be sampled when it is fed.

Sampling of concentrates

• Concentrates should be collected in random from different bags and mixed thoroughly and a sub-sample should be drawn. The following procedure can be adopted as recommended by BIS. Sampling is done based on total number of bags.
• If the total number of bags is 10 sampling is done from all the bags.
• 10 – 50 bags sampling is done at random from any 10 bags
• 51 to 100 bags sampling is done at random from 10 % of bags
• 100 to 500 bags sampling is done at random from 5 % of bags (minimum 10 bags)
• For concentrates stored in bins it is desirable to use suitable probes to draw out samples. Otherwise random grab samples from 10 – 15 areas in the bin can be drawn, mixed thoroughly and a sub-sample be drawn.
• The appliance used for collection of samples is called as the sampler. Samplers may be of different types: 1. Simple sampler 2. Probe type sampler (as shown in the fig.) and 3.Vacuum type sampler

Sub-sampling

• Sub-sampling of concentrate is done using the following procedure.
• Make a conical pile of the concentrate.
• Divide the pile into 4 sections.
• Randomly choose one section and its opposite section.
• Discard the rest. Repeat until a suitable sample size is obtained.

The following precautions should be observed while drawing, preparing, storing and handling of samples.

• Samples should not be taken in a place exposed to dampness, dust, breeze, etc.
• The sampling probe should be clean and dry.
• The sampling material, sampling probe, sample container and sample should be free from contamination.
• The sample container should be sealed air tight and labelled accordingly.
• Sampling of ingredients should always be done in the presence of supplier or his representative.
• Samples should be placed in two sealed packets. Out of two sealed packets of sample one is sent for analysis and the other is retained for further reference.
• Samples should be stored suitably to prevent deterioration of the material.

Sampling of faeces

• The total faeces collected in the cage are mixed thoroughly after recording its weight.
• About 500 g of faeces is sampled for further analysis.
• Faecal samples are stored in frozen condition or dried state until further analysis.

Sampling of urine

• About 5 ml of toluene or 25 ml of dilute sulphuric acid is taken in the container in which the urine is to be collected.
• Total urine collected is mixed and 200 ml is sampled for further analysis.