Dairy

How to Balance a Ration When Silage or Forage Quality is Low

Cow : Lactating Cow Nutrition

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Purina Animal Nutrition

Wet and dry growing seasons have an impact on forage quality and quantity, influencing how dairy rations are balanced to maximize milk production. Here are four considerations to help make the most of your forage, even during poor growing conditions:

Considerations for silage fermentation during wet years

The silage fermentation process is critical for consistent feeding performance and milk production. Although the forage may be cool to the touch within a few days, waiting a minimum of three weeks before feeding new crop corn silage allows for adequate fermentation. It also allows silage to cool so it won’t feed as hot and cause stress to the cow’s digestive system.
 
When wet conditions come into play, there are some additional considerations:
  • Wet conditions can delay corn silage harvest. As a result, the plant overmatures and loses moisture, creating grain lower in fiber and starch digestibility. Grain can regain moisture after harvest in the silo, but it needs 90 days for the digestibility to improve. Rushing into immediate feeding of affected corn silage can result in a decline of milk production.
  • Depending on how much carryover forage remains from the previous season, it might not be feasible to wait for silage fermentation. An alternative is bagging some silage outside of the primary bunker at the beginning of harvest for immediate feeding. Ideally, this silage can be derived from shorter season hybrid varieties than can be harvested up to three wees earlier.
  • Flooding can wash dirt and organic matter onto the corn plants. High moisture levels (above 70%) or high ash levels can extend the period before silage is stable. There is also a high potential for a second, destructive, clostridial fermentation. In these cases, it may be best to feed within 60 days of ensiling or at least get it fed out during cold weather.

Maximize forage quality and quantity during drought years

The most common problem during drought years is a lack of forage quantity. When quantity is an issue, you can add other forages, like straw, to the diet to help maintain roughage. Fall cover crops, such as winter wheat, triticale or ryegrass, can also be added to the diet to increase forage quantity.
 
Drought conditions also bring excess heat, causing plants to mature faster. Maximize forage quality by harvesting before the plant over matures.
 
Pollination tends to be deficient in drought years, too, causing corn ears to have fewer kernels and reduced grain fill. Monitor how ears are filling and the maturity of the plant to ensure you’re getting into the field before the quality starts dropping, typically after corn has dented.  

Watch for mycotoxins and other toxicity issues

Depending on the weather conditions during the growing season, there are several toxicity issues to watch for. Below are just a few:
  • Molds and yeast may be higher in forages during wet years. When wild yeast counts are high, it can depress butterfat production for cattle while causing heating of the silage bunker face and in the feed bunk. If mold is present, it is a sign of other potential problems like mycotoxins.
  • Mycotoxins are poisons produced by mold. Mycotoxins in corn silage or hay can result in lower feed consumption, altered rumen fermentation, suppressed immunity, reduced reproduction rates and more.
  • Nitrates are a concern during dry growing seasons since there isn’t enough water to help distribute nitrates throughout the plant. The nitrates accumulate in the stems of the plant, particularly in forages like sorghum and corn. Cutting the plant at a higher height can lower nitrate levels in the forage while feeding a higher energy ration can help the rumen process the nitrates better.
  • Prussic acid can be present in drought years and after a frost has occurred in sorghum or Sudangrass. Prussic acid is mainly a problem when grazing. Waiting 7-10 days before grazing, baling or chopping allows the hydrogen cyanide to dissipate.
Mycotoxin testing and analyzing for other toxins can help limit potential nutritional problems. Conduct mycotoxin testing in new crop corn silage after harvest. If toxins are found, forages should be retested and monitored to reduce the risk of setting back cow performance or potential cattle mortality.

Extend forages with supplementation

Grains and byproduct supplementation can help provide your herd with adequate nutrition when forage quality or quantity is lacking. Testing forage quality from time to time helps you decide what else to add to the ration.
 
Here are some byproducts and grains to consider when forage quality is lacking:

Need more digestible fiber?
  • Corn gluten feed
  • Soy hulls
  • Beet pulp
Need more energy? Feed higher quality forages to lactating cows first, since they have more nutrient requirements.
 
Involve your nutritionist in ration conversations starting before harvest time begins. Having a nutritionist review current forage inventories can help decide the best balance between quality and quantity to target at harvest. Then they can proactively recommend additional feedstuffs or supplementation.
 
Find out what feed intake data can tell you about your herd.