Grassland Evaluation Contest Study Guide	Fifth Edition: October 2005
Grassland Evaluation Contest Rules - Matching Livestock and Forage
How many pounds of forage dry matter does this herd need to consume per day during each of these seasons?   lbs. D.M. needed Spring ________ Summer ________ Fall ________ Winter ________ Calculating Forage Dry Matter Intake Requirements Although cattle need certain forage quality at specific stages of production, they also need adequate quantity. Estimating the total forage need is not difficult, but will require some calculation. The pasture stocking rate and hay supply can both be estimated in advance if animal needs and forage production is known. Forage requirements vary not only with the animal's stage of production, but also by body size. Large animals need more feed to maintain themselves than do smaller animals. The following table gives guidelines for estimating forage Dry Matter Intake (DMI) by certain classes of animals. These figures are given as a percent of body weight (BW) to account for the difference in forage requirement due to body size. NOTE: Notice that the percentage of forage DMI changes for each stage of production as already discussed in question 1. of this section. Approximate Daily Forage DMI Requirements For Different Classes of Cattle Animal Daily Forage DMI Requirement (% of BW) Dry beef cow 2 % Lactating beef cow (avg. milk prod.) 2.5 % Lactating beef cow (Superior milk prod.) 3 % Bull (during breeding season) 2.5 % Bull ( not during breeding season) 2 % Growing steers and heifers 3 % The following example illustrates how to calculate forage DMI requirements. Example: Calculate the daily forage dry matter needs of this herd during the spring grazing period: Spring-calving beef herd 30 cows - lactating (avg. prod.) (avg. weight =1,100 lbs.) 1 bull - 2,000 lbs. 10 heifers - avg. weight = 750 lbs. Solution: 30 lactating cows X 1100 lbs. = 33,000 lbs. 1 breeding bull X 2000 lbs. = 2,000 lbs. 10 heifers X 750 lbs. = 7,500 lbs. The cows are lactating so their requirement is 2.5 % of their body weight per day. During the breeding season the bull still needs 2.5 % of BW also. The growing heifers need 3 % BW per day. 33,000 X 0.025 = 825 2,000 X 0.025 = 50 7,500 X 0.03 = 225   1,100 lbs. forage dry matter needed per day Example: Calculate the daily forage dry matter requirement for the same herd if the cows are dry in STAGE 3. Solution: The herd needs less forage because the cows are dry and their nutrient and dry matter requirements are lower. The heifers are still growing so they still need 3 % of their BW per day. The cows and bull can be calculated at 2 %. 30 dry cows (1100 lbs. avg. wt.) = 33,000 lbs. 1 bull (2,000 lbs.) = 2,000 lbs. 10 heifers (750 lb. avg. wt.) = 7,500 lbs.   33,000 X .02 = 660 lbs. per day for cows 2,000 X .02 = 40 lbs. per day for bull 7,500 X .03 = 225 lbs. per day for heifers 925 lbs. dry matter needed per day for this herd. Return to Grassland Evaluation Contest Study Guide