B 86 Pearson Square Balancing a Ration Lesson
B 86 Pearson Square Balancing a Ration
Lesson Outline Calculating amounts of feed needed Selecting feed ingredients Using the Pearson square Infovets Educational Resources – www. infovets. com – Slide 2
Pearson Square The Pearson square is a tool used for simplifying and balancing rations. It shows the proportions or percentages of two feeds to be mixed together to give a percentage of the needed nutrient. Infovets Educational Resources – www. infovets. com – Slide 3
Calculating Feed Amounts If pigs have an industry average feed conversion ratio of 3. 5, and you purchase a 50 lb weaner pig and want him to weight 250 pounds by the fair, how many pounds of feed is it going to take to raise this pig to 250 pounds? 250 pound finished hog minus 50 pound weaner = 200 pounds of gain. 200 pounds X 3. 5 = 700 lbs of feed. A feeding standards table shows that an 18% crude protein ration is needed. Infovets Educational Resources – www. infovets. com – Slide 4
Select the Feed Ingredients Feeds should be selected based on the price of the feed, the availability of the feed, and the desirable nutrients found in the feed. Lets say corn and soybean meal (SBM) are selected as feeds. A feed composition table indicates: Corn has 8. 9% crude protein SBM has 44. 4 % crude protein Infovets Educational Resources – www. infovets. com – Slide 5
Using the Pearson Square Use the Pearson square to calculate how much corn and soybean meal need to be mixed together to make 700 lbs. of feed and still achieve 18% crude protein. Infovets Educational Resources – www. infovets. com – Slide 6
Step 1 Draw a 1 to 2 inch square. Place diagonal lines across the square. Infovets Educational Resources – www. infovets. com – Slide 7
Step 2 Write the percentage of crude protein needed by the animal in the center of the square where the diagonal lines cross. (You would have to look that information up on a feed chart for that animal. ) 18. 0 Infovets Educational Resources – www. infovets. com – Slide 8
Step 3 Write the feeds to be used at each corner. The primary feed always goes in the bottom left. The supplementary feed in the top left. (In this case it doesn’t matter. If you were feeding hay and corn, hay would be the primary feed. ) Place the percent of crude protein in the feeds after the name of the feed. • • Corn 8. 9% 18. 0 • • SBM 44. 4% Infovets Educational Resources – www. infovets. com – Slide 9
Step 4 Take the protein level of each feed ingredient and subtract it from the amount of protein needed in the center of the box and record it in the opposite corner. • Corn 8. 9% 26. 4 parts corn 44. 4 – 18= 26. 4 18 – 8. 9 = 9. 1 18. 0 • • SBM 44. 4% Infovets Educational Resources – www. infovets. com – Slide 10 9. 1 parts SBM
Pearson Square 1. 2. 3. Note: A negative number is undesirable, so if the protein in the feed is higher than what is needed, just subtract what is needed from the feed. However, if the protein in the feed is a smaller number than what is needed, subtract what is needed from what is • Corn 8. 9% 26. 4 parts corn in the feed. 44. 4 – 18= 26. 4 18 – 8. 9 = 9. 1 18. 0 • • SBM 44. 4% Infovets Educational Resources – www. infovets. com – Slide 11 9. 1 parts SBM
Step 5 The numbers at the two right corners are parts of the two feed ingredients that are needed. 26. 4 parts corn +9. 1 parts soybean meal (SBM) 35. 5 total parts Infovets Educational Resources – www. infovets. com – Slide 12
Pearson Square Corn 8. 9% 26. 4 parts corn 35. 5 total parts 18. 0 SBM 44. 4% 9. 1 parts SBM 35. 5 total parts Infovets Educational Resources – www. infovets. com – Slide 13
Step 6 The percentage of each feed needed in the ration can be found by dividing the number of parts by the total parts, then multiply by 100. 26. 4/ 35. 5 =. 744 x 100 = 74. 4% corn 9. 1/ 35. 5 =. 256 x 100 = 25. 6% sbm Infovets Educational Resources – www. infovets. com – Slide 14
Pearson Square Corn 8. 9% 26. 4 parts corn 35. 5 total parts 74. 4% 18. 0 SBM 44. 4% 9. 1 parts SBM 35. 5 total parts 25. 6% Infovets Educational Resources – www. infovets. com – Slide 15
Step 7 The amount of each feed ingredient for a large batch of feed is determined by multiplying the percentage of each by the total amount of feed desired. Our batch of feed = 700 lbs x. 744 = 520. 8 lbs Corn 700 lbs x. 256 = 179. 2 lbs SBM 700 lbs 0 f feed @ 18. % Crude Protein Infovets Educational Resources – www. infovets. com – Slide 16
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