This little piggy went to market and this little piggy stayed home
Posted on January 15, 2013 in Swine Performance
By Julie Salyer
Over the years, producers have used many different to help lower economic loss by answering the questions of “when” and “how many” pigs to top, leading to lower group weight variation when taking pigs to market. However, many might still be missing the mark. Vita Plus has adopted helpful tools
that map load weight variation so you can see where you are and where you have historically been for each group in order to help plan for the future. Additionally, some helpful techniques can be used to quickly and easily gain a better estimate of your group variation and more closely match target weights. Chad Paulk, a Ph.D. candidate from Kansas State University, conducted a study to determine the optimal sample size and method used to estimate the standard deviation (measure of variation) of body weight for a group of pigs in the barn. As Paulk points out, “past studies have determined the accuracy and precision of sampling methods producers use to determine mean weight of a group of pigs in the barn.” He also said, “Although knowing the mean weight is important, understanding how much variation or dispersion exists in individual pig weights within a group can also enhance a producer’s ability to determine the optimal time to top pigs.” Once you’ve determined the mean barn weight, exactly how can you quickly estimate the variation of pig weights in the barn? In other words, how do you decide which piggy goes to market and which piggy stays home? According to Paulk’s study, “the distribution of pig weights can be practically estimated by weighing the heaviest and lightest pigs in 15 pens.” Here’s how it works. Let’s say you’ve already determined the mean weight of your pigs is 250 pounds. Next, randomly select 15 pens and weigh the visibly heaviest and lightest pigs in each pen. Take a look at the weights of those 30 pigs. Subtract the lightest weight from the heaviest weight and divide by 6. This will tell you the value of your standard deviation. In this example, let’s say you found your standard deviation to be 25 pounds. Back in math class, we learned that about 95 percent of our normal distribution is accounted for within ± 2 standard deviations from the mean. In this problem, 2 standard deviations equal 50 pounds (25 x 2). So, if we add/subtract 50 pounds to/from 250, we get a range of 200 to 300 pounds. In other words, 95 percent of the pigs in the barn range from 200 to 300 pounds. Now you can use this information to help you decide when to send the first load of pigs to market. Contact your Vita Plus consultant
for more information on how your farm might be able to better track weight variation and decide when to send pigs to market. Click here
to review Paulk’s study. About the author: Julie Salyer previously provided technical support for Vita Plus field and sales staff and conducted nursery research trials as a swine nutritionist. Salyer received her bachelor’s degree at The Ohio State University and master’s degree in swine nutrition at Kansas State University. She is originally from southwest Ohio, where she raised and showed livestock for the county 4-H fair. She was also a student worker at Ohio State’s swine farm and completed an internship in North Carolina for Murphy Brown LLC, which she says was instrumental to where she is today. Salyer is active in church and enjoys hunting, kayaking, hiking and spending time with her husband, Brandon, and their two dogs.