Dairy and feedlot cattle derive a majority of dietary energy from rumen digestion, yet the hindgut is important to consider when feed passage rates increase, feed quality and rumen digestion is challenged (e.g. poor nutrient digestibility or anti-nutritional factors present), and animals are stressed. The hindgut, composed of the cecum, colon, and rectum, is only a fraction of the size of the cow’s rumen, accounting for a mere 14 percent of the capacity for fermentation of the rumen. While the hindgut’s fermentation role is usually to provide 5 to 10 percent of dietary energy within a cow, this portion of the digestion tract can have significant effects on a cow’s performance and health condition[1].
I’ve cited countless hindgut or digestive-upset challenges in the field that broadsided high-performance, seemingly healthy cows – leaving dairymen perplexed and their nutritionist and veterinarian consultant team scrambling to find solutions. This challenge can be difficult to understand, and even harder to pinpoint the exact causes. In the last 20 years, relatively little research was devoted to the role of digestive upsets, hindgut irritation, and fermentation in ruminant nutrition. Symptoms triggering alarm include variable feces (digestive upset), impactions, and even hemorrhaging in the gut.
Contributing factors
Digestive upsets, including excessive hindgut fermentation and irritation, are likely caused by a variety of challenges. Poor rumen nutrient digestibility, increased feed-passage rate, animal stress, and anti-nutritional compounds such as yeast, mold, and mycotoxins are contributing factors.
Figure 1. DIgestive upset arises from a number of different challenges
Feeds that pass through the rumen too quickly due to increased energy demands from the cow, slug feeding, or inadequate fiber particle size can increase hindgut fermentation, leading to a more volatile gut environment and digestive challenges. Cold weather has also contributed to the potentially challenged feedstuffs from last year’s harvest. These feeds harvested and stored during cold weather may not have optimally fermented, diminishing digestibility by the cow relative to forages from years past. I have recently seen an increase in “odd” forage and grain fermentation reports that I speculate resulted from such situations. The suboptimal fermentations could in turn add to poor rumen starch digestion (less prolamin breakdown) and lead to compensatory (added) starch digestion in the hindgut.
Beyond a more volatile digestion in the hindgut, intestinal tract challenges could result from an onslaught of toxins, bacterial or fungal infection, and even lead to Hemorrhagic Bowel Syndrome (HBS). Dr. Adam Ward of Prairie Veterinary Associates helped me understand that HBS can result from Clostridium perfringens overgrowth in the gut. There is a suspected, yet unproven, relationship between Aspergillus fumigatus and C. perfringens as a cause of HBS. The toxins secreted by the bacteria and fungal overgrowth cause the gut lining to degrade and bleeding into the lumen ensues. At this point, some cows may become anemic, or even worse, a clot can form, becoming an obstruction that could prove fatal. Severe cases of the disease lead to degradation of the mucosa, ultimately allowing bacteria and fungi to enter the bloodstream and infect the entire body. It’s important to note that HBS is characteristically a small intestinal affliction, however the inciting sources remain similar to those of other hindgut fermentation issues (slug feeding, rumen acidosis, increased gut passage rates, etc.)
Another hindgut issue contributing factor is stress from the Midwest’s current cold-weather conditions. Animals dealing with cold stress may exhibit a suppressed immune system, opening them up for bad bacteria within the gut. Slug feeding is secondary effect of the cold weather. These large, concentrated meals, as opposed to regular snacking at the bunk, trigger slugs of nutrients to pass through the rumen. This, combined with irregular feeding, can wreak havoc on digestion within the cow. Further yet, water intakes are likely decreased due to frozen waterers.
Dr. Ward sheds some light on the physiological issues he has seen in the field this winter that could also contribute to the challenges facing dairies across the frozen tundra. “I’ve seen some dairies feeding high-moisture corn that has resulted in frozen corn chunks melting after feeding, resulting in the cow eating a significant amount of corn,” explains Dr. Ward. “In most cases this winter, the problems that have risen to the top are a result of feeding challenges with frozen feed and inconsistent mixing of feed.” Dr. Ward goes on to explain the grain overloads and digestive upsets that result.
Considerations
Dr. Ward suggests that one way to combat this minimally understood digestive challenge is to first and foremost be aware of its existence. Consistency is key. Keep an eye on cows showcasing the symptoms discussed, and don’t hesitate to have a veterinarian examine any animal that suddenly acts depressed or sharply drops in milk production. Simple, proactive measures such as consistent feeding, frequent feedings, and making fresh feed available after milking can also help to get the animals in motion and back to the bunk. While not yet applicable, working to put up better quality, more consistent forage this upcoming summer can also help proactively prevent such challenges.
Keep in mind that we are dealing with a variety of factors related to digestive upsets. If you suspect your herd or the herds you consult are challenged, work with the veterinarian and confirm diagnoses. From an analytic standpoint, mold, yeast, and mycotoxin analysis can help quickly identify one facet of hindgut digestive upset causes. Using this information can pinpoint a nutritional program option to improve the affected animal’s health and performance.
If interested in this aspect, I recommend first assessing Total Mixed Ration (TMR) yeast and mold levels. If levels are above action limits, the retained TMR sample can be further tested for toxins (known tissue irritants and immune-suppressing compounds). Keep in mind mold, yeast, and toxin load are only one of potentially several factors to consider this year (as indicated in Figure 1). Another option is to test individual TMR ingredients for anti-nutritional factors and determine the causative ingredients. Heavily contaminated ingredients (concentrates or forages) can then be managed appropriately.
Call Rock River Laboratory for support on any digestive challenges you may be seeing in the field and we can help put together an analysis program.
Source: Rock River Laboratory
