Industry Q & A What concerns should I have feeding distillers grains or other ethanol by-product feeds? When corn grain is fermented to make ethanol, the starch is removed from the corn. The general rule is that after ethanol fermentation, the composition of the by-product feed will be three times more concentrated than corn before the process (except for starch). So, 10% crude protein corn would produce 30% crude protein distillers grain. The same would be true for sulfur, phosphorus, fat and mycotoxins. We know that increasing by-product feeds can cause central nervous system disorders if sulfur levels in the diet get too high. However, in a year where fumonisin or aflatoxins (both are mycotoxins) are high due to drought stress crops, they would be three times as high in the by-product feeds from those grains. Understanding the “rule of three” is important when feeding by-product feeds from ethanol production. If I wait to castrate my bull calves at weaning, will I improve my weaning weights? No. Studies done at Kansas State University, the University of Arkansas and the University of Florida all show that calves castrated during the first week of life have the same weaning weights as their herd mate bulls that were castrated at weaning. For calves to have increased growth rates, the testicles must be producing testosterone. Testosterone is not produced by the calf ’s testicles until the bull calf goes through puberty which occurs around 8 to 10 months of
age. We wean cattle at 6 to 7 months of age, prior to puberty, therefore there is no growth or weight advantage to leaving the bulls intact. Bulls castrated at weaning or at feedlot entry have over 150% the morbidity rates and mortality rates of cattle that arrive at the feedlot as steers. Castrating calves early in life is our best option for all involved in the beef industry and especially the bull calves. Should I be worried about grass tetany in my cows? Grass tetany occurs in cows when the blood levels of magnesium are too low. This syndrome usually occurs in lactating cows that are turned out on lush green forages with low magnesium levels (less than 0.2%) and high potassium levels (greater than 3%). Low calcium intake from the forage can also contribute to the grass tetany problem in cows. Magnesium is lost from the cow in the milk. The combination of low magnesium forages with peak lactation makes early spring the highest risk time period to see grass tetany in cows. Older cows in the herd with calves on their side are the highest risk for grass tetany. The best way to prevent grass tetany is working with your nutritionist to supplement your cows with magnesium in the mineral about 30 days prior to pasture turnout. The cow’s magnesium requirement during lactation is around 13 to 15 grams per day but can be increased to two times that level in certain scenarios. Work with your nutritionist to develop a mineral program to prevent disease and promote reproductive efficiency in your cow herd.
