Nutrient Testing
Table of Contents
IntroductionThere are many factors that determine if, and how much of, an individual ingredient to include in a livestock ration. Such factors include:
Feed analysis is the first step in ensuring proper ration formulation, with the goal of maintaining a healthy and productive livestock herd. Analyze all feed sources to determine their nutritional value. This is the only way to assess the value and cost effectiveness of a potential feed ingredient. Next, design a detailed program to monitor consistency and ensure ongoing product quality. When considering the use of alternative feeds in a livestock ration, pay particular attention to the nutrient content and consistency of the ingredient. Some alternative feeds, such as whey and pasta, are relatively consistent in their nutritional quality. Others vary widely in nutrient composition (e.g. bakery waste and confectionery products). Some by-products are of so little nutritional value they either are not
worthwhile alternatives to conventional feeds or may only suit specific
livestock groups. For example, many cull fruits, or vegetables and processing
wastes, are so high in water content their value is limited for most classes
of swine. However, they may still be suitable as feed ingredients for
dry sows or cattle. Before deciding which products to use, waste generators
and livestock producers must know their nutritive value and variability
in order to formulate rations to meet production goals. Obtain feed analysis
from a reputable laboratory for information on any potential ingredient's
nutrient content. Repeated analyses can help determine nutrient variability. Collecting a SampleThe most important part of any laboratory analysis is collecting a representative sample. The analysis will only be as good as the sample submitted. A small sample must accurately represent the entire load or batch. To collect a sample for analysis:
Store collected samples in sealed plastic bags, removing as much air
as possible to prevent moisture loss and sample deterioration. If the
sample cannot be sent to the lab for several days, keep in the freezer.
Minimize sample transportation time to ensure freshness. Samples must
be labelled clearly according to the type of product, the date the sample
was taken, as well as a contact name, address, and phone number. Laboratory AnalysisDepending on the feed ingredient being considered, there may or may not be sufficient information to determine its suitability for feeding to livestock. For common ingredients and some products, such as milk by-products, apple pomace and chocolate waste, there is an abundance of information available on nutrient composition and suggested inclusion rates for livestock. In other cases, however, such as confectionary or grocery store waste, there may be little or no information. Many of these products are variable in composition and need to be analyzed frequently. Both the nutrient analysis and variability are important considerations for ration balancing. Be aware that nutrient testing alone may not provide all the relevant information needed to make a decision. Depending on the product, additional analysis for toxins, pesticides, heavy metals, drug residues, additives, preservatives, microbiological contamination or other compounds may be necessary. A nutrient profile helps identify the alternative feed's classification. Feeds can be classified as:
An alternative feed can then be compared to a more common feed ingredient
in the same class. A basic analysis should include, at the very least, dry matter (DM),
protein (CP), calcium (Ca), phosphorus (P), salt and fat. Most laboratories
offer packages that decrease the overall cost of the analysis if ordering
a full profile. For example, packages that test for both DM and CP usually
cost $12-$17. For individual analyses, expect to pay $6-$15 for minerals
and $10-$15 for ether extract, which is the laboratory test for fat. For
current pricing, contact the laboratory directly (phone numbers are listed). Understanding the TerminologyThere are 2 types of analysis available for determining the nutrient
content of feeds: wet chemistry and Near Infrared Reflectance (NIR). It
is important to understand the difference between the 2 methods when considering
the analysis of an alternative feed ingredient. What is Wet Chemistry?Wet chemistry is the preferred method for analysis of non-traditional
feedstuffs because it more accurately measures the nutrient content. Analytical
procedures are standardized for each nutrient test. Advantages:
Disadvantages:
What is Near Infrared Reflectance (NIR) Analysis?NIR relates a sample's reflectance of near infrared light to its chemical composition. It relies on prediction equations of nutrient levels, rather than actual measurements. Before any feed can be analyzed using NIR analysis, hundreds of calibration samples of the same feed type must be analyzed using standard laboratory wet chemistry methods and then tested using NIR. By relating the results from the standard analysis to NIR, a calibration set of data for the NIR instrument is developed. This is critical for accurate results. NIR analysis is not suitable for determining the nutrient content of most alternative feeds because information on the nutrient content of these feeds is limited and nutrient levels often are quite variable. Advantages:
Disadvantages:
NIR analysis is an inexpensive and rapid alternative best suited to analysis of hay, haylage, corn silage, high moisture corn and grains since prediction equations for these feedstuffs are plentiful. What is Dry Matter?The most important concept in assessing feed analysis results is the
expression of nutrient content on a "dry matter" or "as
fed" basis. All feed ingredients contain water, but some have more
than others. (Consider the difference between orange pulp at 75% water
and corn at 15% water.) The dry matter content of a feed is the most important
component because it contains almost all of the feed nutrients. The amount
of dry matter in a feed is simply: When comparing the nutritive value of different ingredients, it must be done on a dry matter basis for a valid comparison. To convert a specific nutrient from as fed to dry matter basis, use the formula: (Nutrient content (% as fed basis) x 100) ÷ Dry matter content (%) = Nutrient Content (% dry matter basis) To illustrate this, when comparing the protein content of orange pulp (2.2%) and corn (9%) on an as fed basis, corn appears to be a better source of protein. On a dry matter basis, however, orange pulp tests 8.9% crude protein, corn 10.6%. The as fed protein comparison, then, is misleading. Sometimes it is confusing to convert as fed and dry matter nutrient values.
A good rule of thumb is that the nutrient content expressed on a dry matter
basis is always larger than the same nutrient content expressed on an
as fed basis. This is because the as fed nutrient value is diluted with
water. Ration FormulationConsult a qualified nutritionist to properly balance the ration using
the results of nutrient testing. Rations based totally on alternative
feeds will still require additional supplementation of minerals and vitamins
and possibly other nutrients. Most successful by-product feeders rely
on a mix of traditional feed ingredients and alternatives to meet their
livestock's nutrient requirements. Nutritional advice and ration formulation
assistance is readily available through many feed dealers, premix companies,
veterinarians and independent consultants. Relevant OMAFRA FactsheetsFor further general information on feed analysis and feeding, refer to
the following Factsheets available from OMAFRA:
Table 1. Feed Analysis Laboratories (Current listings as of November 2002)
2. Accredited for testing certain nutrients through the Standards Council of Canada. For more details contact the Standards Council of Canada, (613) 238-3222, http://www.scc.ca. Please Note: Each laboratory has its own "numbering" system for identifying the different packages and abbreviations for certain analyses.
For more information:
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