By Joel DeRouchey, Mariana Menegat, Mike Tokach, Steve Dritz, Jason Woodworth and Bob Goodband of Kansas State University
Swine producers, feed mills, nutritionists and veterinarians often ask questions about the quality and composition of finished feed or feed ingredients. Analyses are performed to monitor ingredient and feed quality on a regular basis. Not only does this help avoid errors in estimating nutrient content, but it also helps identify inaccuracies in feed formulation or feed manufacturing. Chemical analyses are also important to assign nutritional values to feed ingredients. If you want to obtain accurate nutrient values, you need to conduct appropriate sampling and analysis.
1. Secure your samples
The most common sampling equipment for bulk feeds or feed ingredients is the slotted grain probe, which can be manual or automated. The slotted grain probe should be long enough to reach the bottom of the bulk carrier to obtain a representative sample from top to bottom. Samples should be collected from at least 10 evenly spaced locations in the bulk carrier. Alternatively, a pelican sampler is also commonly used to steam cut samples during loading or unloading of bulk feeds or feed ingredients.
The sampling equipment for bagged feeds or ingredients is the bag trier. The bag trier should be inserted diagonally in one corner to reach the opposite corner of the bag. At least 10 randomly selected bags should be collected from the lot.
The sampling procedure of liquid ingredients, such as fats, oils and amino acids, can be performed from bulk, tanks or barrels, or during unloading. The sampling equipment for liquid ingredients in bulk is the bomb sampler. For tanks or barrels, it is the drum thief sampler. In both cases, liquid ingredients should be stirred before sampling to ensure a proper distribution of nutrients. At least 500 ml or 1 pint of liquid ingredients should be collected.
Samples of complete feed are collected from feeders by probe or hand-grab sampling. Samples collected with a probe have less variability and require fewer number of samples. Samples should be collected from at least six feeders with probe and nine feeders by hand. Approximately 1 to 2 lb of feed should be collected per feeder and mixed in a composite sample.
2. Prepare samples for analysis
First, composite samples of feeds or ingredients should be mixed thoroughly. Then, samples are split with a riffle divider or by the quartering method. The process should yield two samples of approximately 1 lb each. One sample should be submitted for analysis and a second sample retained as a backup. Samples for analysis should be placed in plastic or paper bags for submission. Plastic bags are conventionally used, but paper bags are preferred for high-moisture or mold-contaminated samples to prevent condensation of moisture and proliferation of mold growth. Samples should be identified with sample number, date and content.
3. Decipher analysis results
The analysis results should be interpreted on as-fed, not on dry-matter basis. These values can then be compared with the expected nutrient specifications in diet formulation. The errors associated with sampling can be minimized by following the procedures for sample collection described above. The analytical variation is usually taken into consideration to determine acceptability of feeds and ingredients, which is generally around 15% to 20%.
Read more in the Feed Sampling and Analysis Factsheet in the 2019 KSU Swine Nutrition Guide at ksuswine.org.
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