How to Read a Forage Analysis Report

Transcription

1 Page 1 of 7 How to Read a Forage Analysis Report What Does It Mean? edited by: Steve Duckett & Tony McGaha, Agricultural Extension Agents Now that you have forage analysis reports for your hay, what do they mean? The following is meant to be a brief summary of how to read the forage analysis report and how to use the information it reveals for your benefit. Hay is fed to livestock mainly to provide protein and energy. The macro- and micro-minerals should be provided in a good mineral supplement. In order to compare the nutritional contents of different hay sources, always look at the dry matter basis column (Refer to the sample feed analysis report). Protein content is evaluated as the percent CP (crude protein); however, when figuring rations, Adjusted Crude Protein % is the value to use in your calculations. Available energy is evaluated as percent TDN (total digestable nutrients) for ruminants or percent ADF (acid detergent fiber) for horses. If you want to evaluate the general quality of your hay, compare your CP, TDN and ADF figures to those in Tables 1 and 2. If we refer to our example on page 6, this bermudagrass sample has a CP value of 17%, TDN of 63% and ADF of 37%. When we look at Table 1 we see that this lies within the high quality range for grass hays for ruminants. When we look at Table 2 we find that this grass hay is of average to high quality for horses. Figure 1. Sample Forage Analysis Report. SAMPLE NUMBER: 0420 DESCRIPTION: SAMPLE 1 FORAGE TYPE: FORAGE FORM: MATURITY STAGE: LABORATORY: RESULTS: GRASS FORAGE HAY VEGATATIVE, NO HEADS AS SAMPLED BASIS Dry Matter, % DRY MATTER BASIS

2 Page 2 of 7 Crude Protein, % Unavailable Protein, % Adjusted Crude Protein, % Acid Detergent Fiber, % TDN, % NE(Lactation) Mcal./lb Calcium, % Phosphorus, % Sodium, % Magnesium, % Sulfur, % Potassium, % Copper, ppm Iron, ppm Manganese, ppm Zinc, ppm Nitrate Ion, % Table 1. Forage quality indicators for ruminants. Forage Type High Quality Average Quality Low Quality Legumes (eg. alfalfa) CP 18-23% TDN 60-65% CP 15-17% TDN 55-66% CP below 15% TDN below 55% Grass/Legumes (eg. fescue/clover) CP 15-18% TDN 57-62% CP 11-14% TDN 55-57% CP below 10% TDN below 55% Grass (eg. bermudagrass) CP 12-14% TDN 57-60% CP 9-11% TDN 54-57% CP below 7% TDN below 54%

3 Page 3 of 7 Table 2. Forage quality indicators for horses. Forage Type High Quality Average Quality Low Quality Legumes (eg. alfalfa) CP 18-23% ADF below 30% CP 15-17% ADF 30-37% CP below 15% ADF above 37% Grass/Legumes (eg. fescue/clover CP 15-18% ADF below 30% CP 11-14% ADF 30-37% CP below 10% ADF above 37% Grass (eg. bermudagrass) CP 12-14% ADF below 30% CP 9-11% ADF 30-37% CP below 7% ADF above 37% Matching Livestock Nutritional Requirements with Hay Sources Knowing the general quality of the hay is fine, however, as we can see from Tables 1 and 2, each quality category has a range of values. If we fed only by quality grade, it would be possible to not meet the nutritional requirements of the animals we are feeding. For this reason, it is best to match the protein and energy requirements of our livestock to the hay we have bought or produced. Table 3,(Beef), Table 4, (Goats), Table 5, (Sheep), and Table 6, (Horses) give the general requirements for the major species of livestock in Western North Carolina. As an example, let's say that we are feeding lactating beef cows with high milk production. Using the previous bermudagrass sample, we see a CP of 17% and a TDN of 63%. This is high quality grass hay. Common sense tells us that it would be excellent for lactating cows; however, when we look at the nutritional requirements for lactating cows with high milk production, we find that this hay meets the protein requirements (12% CP needed) but fails to meet the energy requirements (65% TDN needed). In this case, an energy supplement is needed. Table 3. Nutrient requirements of Beef Cattle Bulls % Crude Protein % TDN Developing, 750 lb Regaining condition

4 Page 4 of 7 Maintenance Cows Dry Average milk High milk First calf heifers Average milk High milk Developing heifers Stockers 350 lb lb lb Table 4. Nutrient requirements of Meat and Fiber Producing Goats. % Crude Protein % TDN Buck ( lb) Does (80 lb) dry (pregnant) early late

5 Page 5 of 7 lactating average milk high milk Kids (ADG >.44 lb/day) weanling (30 lb) yearling (60 lb) Table 5. Nutrient requirements of Sheep. Ewes % Crude Protein TDN maintenance gestation last 4 weeks lactating single twins Lambs finishing replacement rams replacement ewes Table 6. Nutrient requirements of Horses.

6 Page 6 of 7 % Crude Protein % TDN Long Yearling 18 months Mature Horse (1100 lb) maintenance light work moderate work Mare late pregnancy lactation, month To calculate Digestible Energy (DE) from the information on your feed analysis report, use the following formula: DE (Mcal/Kg) = (%ADF) (%CP) (%ADF)2 Using values from the sample feed analysis report, Digestible Energy calculates as follows: DE (Mcal/Kg) = (37.48 ADF) (17.03 CP) (37.48 ADF)2 = ( ) = = 2.23 Mcal/kg To convert Mcal/kg to Mcal/lb: DE = 2.23 Mcal/kg x kg/lb DE = 1.01 Mcal/lb For more information on creating balanced rations for your horses or livestock, contact your county North Carolina Cooperative Extension Service office or contact the Cooperative Extension Service in your state.

7 Page 7 of 7 Last revised on 11/6/98 Maintained by: Karen Garrett