Feed hygiene is critical to herd performance

It is no secret that forage quality can make or break the productivity — and profitability — of a herd. When we accurately identify feed hygiene challenges, we can take steps to minimize negative outcomes and prevent future occurrences.

The cost of hygiene issues

I often observe feed hygiene-related issues in cows that are in the top 10% of the herd from a production standpoint.  These cows are typically in peak milk and have high intakes to meet the energy demands of that milk production. When faced with a pathogen or toxin challenge, these cows will repartition energy to fuel an immune response and thus go off feed, stop ruminating, and quickly drop in milk production.

If high-group feed intakes and milk production start to decline, farm consultants and managers should walk cow pens. Look for excessive amounts of undigested fiber in manure piles, variable manure consistency within each pen and mucin casts.  Excreted mucin casts indicate that the intestinal barrier between the gut and the bloodstream may be compromised, allowing pathogens and toxins to enter. This activates the cow’s immune system and can create milk fever-like symptoms where the cow is unable to get up.

Avoid mud and manure

The first step in determining whether feed hygiene is related to health challenges is to examine ration formulation, mixing and feeding processes, and the equipment used to mix and deliver feed.

Consider any areas where mud or manure may be incorporated into the total mixed ration (TMR) or tracked into the feedbunk.

• Does your TMR mixer wagon or feed push-up equipment travel through manure prior to entering the feed alley?
• Is the same machinery used for handling manure and feed push-ups?
• Does your feed pad or feed center have poorly drained low spots where water and mud collect alongside feed ingredients?

If all these processes are managed correctly, the next thing to evaluate is your forages for any problems that may impact animal health or performance.

Clostridial concerns

Clostridial fermentation is most likely to occur in alfalfa, grass or small grain silages. Due to their high protein and mineral content, these silages have a higher buffering capacity, which means it is more difficult to drive down the silage pH. This less acidic environment is conducive to clostridia growth.

If the silage is put up wet, look at its pH and fermentation profile. In general, we target a pH of less than 4.2 for these silages to prevent clostridial fermentation; however, the minimum pH required to prevent growth of Clostridia is dependent on the dry matter (DM) and the crop type (Figure 1).

When looking at the fermentation profile, I want to see a lactic-to-acetic-acid ratio greater than 3:1 and butyric acid less than 0.1%.  If a silage has undergone clostridial or enterobacterial fermentation, it will likely have a high pH and above-average butyric acid level, ash content, and ammonia content. Typically, the protein quality is compromised due to degradation of proteins in the ensiled crop.

You may also see the presence of biogenic amines — the main contributor of palatability and intake issues. Biogenic amines — such as cadaverine, histamine, and putrescine — can be detrimental to gut motility and digestion, resulting in manure with undigested fiber, reduced rumination, cows off feed, reduced protein digestion, higher milk urea nitrogen (MUN), and extreme drop in milk production.

Forages can be tested for levels of biogenic amines, Enterobacteria and Clostridia. Work with your nutritionist to determine when the situation warrants this testing and minimize negative effects.

If you’ve identified unhygienic silage as an issue:

• Greatly reduce or eliminate these silages in fresh cow diets, as butyric acid can cause ketosis in fresh cows.
• Reduce feeding rates so cows (lactating and dry) and replacement heifers consume less than 50 grams of butyric acid per day.
• Allow time for the silage to “air out.” As silage is exposed to air, the levels of butyric acid and possibly other volatile compounds will decline.

Prevent future challenges

Alfalfa silage tends to be the most critical silage to focus on. In addition to this crop’s higher buffering capacity, there is also a greater potential to pick up ash during alfalfa harvest. Clostridia live in soil and higher ash content in the silage elevates the likelihood of “bad inoculation” with clostridia.

• Grass, small grains, and corn silage: Target no less than 32% DM at harvest.
• Alfalfa: Target 40% to 45% DM. If you absolutely must put up wet alfalfa silage (less than 35% DM), try to store or segregate the forage in a way that you can feed it quickly. It takes approximately 90 days from ensiling for clostridia to grow and become harmful to the cow.

Consider applying a research-proven inoculant that rapidly lowers silage pH. Fill silos quickly, ensure optimal packing weight to achieve target silage density, and cover it as quickly as it is safe to do so.

Don’t let feed hygiene issues limit your herd’s performance. Focus on quality forages and feed management to support cow health, productivity, and profitability.

This article was originally published in the June 2024 issue of Hoard’s Dairyman. Click here for the original article.