Dairy Sense: Weather's Impact on Corn Silage Quality

August 2022

Production perspective:

This summer has been very spotty with rainfall. Some locations have received strategic precipitation to keep crops looking good, other places it has been more droughty. With corn silage harvest on the horizon, the quality will vary depending on how wet or dry it has been. This can have implications on ration formulation, feed cost, and animal performance. Considering the impact weather has on corn silage quality, regular forage testing could be helpful in making just in time adjustments to minimize reductions in milk production and milk income.

In 2016 and 2017, the Extension dairy business management team examined corn silage quality and its impact on the dairy enterprise financials. It happened that 2016 was a drought year and 2017 received ample moisture so quality comparisons could be made on the diverse growing seasons. Corn silage was sampled in the fall after a few weeks of ensiling and again in the spring after several months in storage. Table 1 shows the differences in quality for herds generating a positive net return in both years. There was a tendency for neutral detergent fiber percent and digestibility to be higher in a drought year compared to silage receiving ample moisture. However, the starch was usually low in a drought year coupled with lower digestibility. The one aspect that differed between the two years for the high profit herds was better feed efficiency in 2016 compared to 2017 (1.59 vs. 1.52). Energy corrected milk was similar but dry matter intakes trended higher in 2017/2018 on rations containing corn silage with lower fiber digestibility. This same tendency was observed for the medium and low profit herds as well.

There was not any commonality in ration formulation approach between years for the high profit herds. Some fed high moisture corn, dry corn or barley, or a combination of these grain types. The amount fed was similar regardless of the corn silage quality. This ration approach was observed for the medium and low profit herds as well. Overall, herds in all profit groups maintained similar production both years, it was the efficiency of how feed was converted into milk that was impacted. Depending on how weather affects the operation’s corn silage quality, dry matter intake efficiency could be an important metric to monitor to keep feed costs in line.

The high profit herds routinely produced the highest yield of forages compared to the medium and low profit herds. This resulted in high profit herds maintaining total feed costs less than $2000/cow compared to the medium and low profit herds ranging from $2300 - $3000 per cow. Cost of production averaged below $18.00/cwt for the two years compared to the medium and low profit herds above $20.00/cwt. Even though the high profit herds were dealt the same external environmental challenges as the medium and low profit herds, they were well managed on the crops, cows, and cash to achieve a positive net return.

Dairy farming is fraught with difficulties; however, the well managed operations seem to persevere. Since corn silage usually makes up much of the forage dry matter, it makes sense to pay attention to the fiber digestibility, starch content and its digestibility. Based on the on-farm project conducted by extension, feed efficiency appears to be the one metric that can be affected by corn silage quality. Since feed costs are remaining high it does warrant monitoring this number and working with a nutritionist to pursue feeding strategies to keep dry matter intake in line.

Table 1. Corn silage quality on high profitability herds¹

¹Seven high profit herds (out of 23 farms) had positive net returns for 2016 and 2017. Corn silage was sampled in the Fall and Spring of the respective years.Corn silage was sampled in the Fall and Spring of the respective years.

Crops to Cow Project: Ishler, V. et al. NESARE ENE 15-136. The Impact of Corn Silage Harvesting and Feeding Decisions on Income Over Feed Costs.

Economic perspective:

Monitoring must include an economic component to determine if a management strategy is working or not. For lactating cows, income over feed cost is a good way to check that feed costs are in line for the level of milk production. Starting with July 2014's milk price, income over feed cost was calculated using average intake and production for the last six years from the Penn State dairy herd. The ration contained 63% forage consisting of corn silage, haylage and hay. The concentrate portion included corn grain, candy meal, sugar, canola meal, roasted soybeans, Optigen, and a mineral vitamin mix. All market prices were used.

Also included are the feed costs for dry cows, springing heifers, pregnant heifers, and growing heifers. The rations reflect what has been fed to these animal groups at the Penn State dairy herd. All market prices were used.

Income over feed cost using standardized rations and production data from the Penn State dairy herd.

Feed cost/non-lactating animal/day.