Agri Analysis, Inc.
Feed and Forage Terminology from Agri Analysis, Inc.
Feed and Forage Terminology from Agri Analysis, Inc.
- As Received
- Dry Basis
- Crude Protein
- Heat Damaged Protein
- Unavailable Protein
- Available Protein
- Soluble Protein
- Acid Detergent Fiber (ADF)
- Neutral Detergent Fiber (ADF)
- Total Digestible Nutrients
- Net Energy-Lactation, Net Energy-Maintenance and Net Energy-Gain
- Relative Feed Value (RFV)
- Relative Feed Quality (RFQ)
- Neutral Detergent Fiber Digestibility (NDFd)
- Volatile Fatty Acids (VFA)
- Yeast/Mold Count
- Protein Dispersibility Index (PDI)
All values under this heading show the content of the nutrients with the moisture in the sample included. Because of the dilution of water, the values will be lower than the dry matter basis.
Values in this column give the nutrient values with the water removed. This allows comparisons to be made between forages. This is the best indicator of nutrient value because forages are evaluated on a dry matter basis.
The approximate amount of protein which is calculated from the determined nitrogen content by multiplying by a factor.
The measure of protein determines if a % was damaged or bound due to excessive heat. This is most commonly found in haylages.
A forage report will not always show this value unless heat damage has occurred. This value will give an indication if excessive heating has occurred, reducing the protein digestibility. All forages have some unavailable protein.
In some reports this value will be the difference between the crude protein and unavailable protein value. However, some laboratories account for the naturally bound protein found in forages.
This is protein which is rapidly degraded to ammonia in the rumen and reported as % of crude protein. Some of this rapidly available protein is needed by the rumen bacteria when their growth is high.
The ADF value refers to the cell wall portions of the forage that are made up of cellulose and lignin. These values are important because they relate to the ability of an animal to digest the forage. As ADF increases the ability to digest or the digestibility of the forage decreases.
The NDF value is the total cell wall which is comprised of the ADF fraction plus hemicellulose. NDF values are important because they reflect the amount of forage the animal can consume. As NDF percent increases, the dry matter intake generally decreases.
Some laboratories use the same formula to calculate the TDN value as they do the Digestible Dry Matter (DDM); therefore, the two values would be the same. Other laboratories will use different formulas, such as:
Alfalfa: % TDN = 96.35 - (ADF % x .15)
Corn Silage: % TDN = 87.84 - (ADF % x 0.70)
As the percent ADF increases, TDN will decrease.
These net energy values are often calculated from TDN values, which in turn are generated from percent ADF. Examples are:
NEL: Mcal/lb = (TDN % x 0.01114) - 0.054
NEM: Mcal/lb = (TDN % x 0.01318) - 0.132
NEG: Mcal/lb = (TDN % x 0.01318) - 0.459
As the percent ADF in the forage increases, the net energy values will decrease.
Relative feed value is an index that combines the important nutritional factors of intake and digestibility. It has no units, but the index allows for comparisons of legume, grass and legume/grass forages. A relative feed value is not to be used for nutritional ration balancing. Instead, it will assist in determining the value of a material for marketing purposes.
Relative feed quality is calculated by estimating the digestibility of the forage dry matter and by determining how much the cow can eat based on its filling capacity. The RFQ index uses fiber digestibility to estimate intake as well as the total digestible nutrients (energy) of the forage. This can be used to more accurately predict the animals' performance and match the animals needs.
Wet chemistry processes determine macro minerals as percent and trace minerals as parts per million (ppm). If the Near Infrared Reflectance Spectroscopy (NIRS) is used, the test will include only the macro minerals. The macro minerals include percent calcium, phosphorus, potassium and magnesium. The use of wet chemistry will if requested include iron as ppm, copper, zinc and manganese.
These are the oils and related compounds found in grains and forages that naturally make-up approximately 2-4 percent of the ration.
This represents the mineral content of the feed or forage. Forages contain 3 to 12 percent ash on a dry weight basis while grains and concentrates contain 1 to 4 percent.
Lignin is the prime factor influencing the digestibility of plant cell wall material. As lignin increases, the digestibility, intake and animal performance usually decreases. As the percent of lignin increases, the percentage of ADF and NDF also increases in forage.
Starch is classified as a carbohydrate. Non-structural carbohydrates reside within the cell and their digestibility is about 90 percent.
NDFd is a measure of the digestibility of neutral detergent fiber. This approach enables nutritionists to formulate better rations. More accurate energy predictions can be made and dry matter intake achieved. Both wet In vitro and NIRS tests are available.
Fermentation analysis will assist in understanding the quality of the fermentation and a silage. Data interpreted will tell us whether an excellent, average or poor fermentation occurred. An analysis report will include pH, lactic, acetic, propionic and butyric acids, ammonia and ethanol.
A yeast and mold count is perhaps one of the most important tests when determining whether microbial changes in a silage will degrade the nutritional content; thus, leading to possible mycotoxin formation. Yeasts counts are a good indicator of unstable or hot silage.
Protein Dispersibility Index (PDI)
The PDI test determines how thoroughly soybeans have been heated to deactivate the trypsin inhibitor. Heat causes a chemical reaction to occur between protein and sugars resulting in a protein-sugar complex known as Maillard Products. This in turn influences the rate of protein being degraded in the rumen.