Beef cow-calf producers are feeling the pinch of low pasture and hay yields due to drought conditions across the state. Corn silage is another feed source that can be used to help meet the herd’s nutritional needs.
Test for toxins before feeding
The drought has negatively impacted many corn fields that may be candidates to chop for cattle feed. Increased risk of high nitrates and mycotoxins in these fields means caution needs to be taken. Nitrate accumulates in the lower portion of the stressed corn plant and is converted into nitrite in the rumen, or if the fresh chopped corn is allowed to heat in a pile. Nitrite then affects the oxygen-transporting capability of the animal, causing asphyxiation (suffocation). Corn stressed during ear development and pollination is also susceptible to mold and mycotoxin development. Mycotoxins can cause reduced feed intake, diarrhea, abortions and weight loss. Both nitrate and mycotoxin levels can be tested for so appropriate action can be taken to keep risk to a minimum. The cost of the tests is minimal compared to the lost value of potential dead cattle and production loss, especially with the current high cattle prices.
Drought stress impact on yield
Drought stress tends to impact yield more than quality. UW Corn Agronomist Joe Lauer evaluated yield and quality data from the UW Corn Silage Trials to determine how drought stress impacted yield and quality of corn silage.
In years where the drought stress was only prior to pollination, forage yield tended to be lower compared to normal years and grain yield was not affected. Corn plants were shorter but had a greater proportion of grain in the silage, resulting in lower neutral detergent fiber content and greater starch content.
In years where the drought stress extended into pollination and grain fill, forage yields were 18 -46% lower. Quality, measured by using the Milk Per Ton quality index, was reduced by 3-8%. The silage had a lower starch content due to lower grain content.
Forage quality and drought-stress
Wisconsin research led by Jim Coors evaluated the forage quality of corn with 0, 50 and 100% pollination of the kernels on an ear in Wisconsin in 1992 and 1993. As ear fill increased from 0 to 100%, whole plant crude protein decreased by 1%, neutral detergent fiber decreased by 8%, acid detergent fiber decreased by 4%, and in vitro true digestibility increased by 3%. These years were not drought-stress years, however, the treatments mimicked drought stress during pollination and ear fill and the results were comparable to what was reported by Lauer.
Source: wisc.edu
Photo Credit: gettyimages-steve-greer
Categories: Wisconsin, Crops, Corn