Cattle, like humans, incur stress daily. They can run short on feed, develop ruminal acidosis, get moved to a new pasture or location, be exposed to coyotes on the prowl or deal with extreme cold and heat events. All of these are examples of the stresses these animals endure. These stress events have one thing in common: They can all cause intestinal dysfunction. This phenomenon is often referred to as “leaky gut.”
The intestine is a major component of the immune system, as it prevents parasites, pathogens, enzymes, acids and toxins from infiltrating the body. Disruptions in this system are referred to as intestinal dysfunction, a loosening/widening of the tight junctions of the intestinal epithelia. These tight junctions are essential to the function of the intestines’ physical barrier. When the tight junctions become dysfunctional, various intestinal components can enter circulation. These components will trigger a cascade of immune system functions and inflammation, causing a huge drain on the energetics of the animal. This energy demand displaces calories that could have been used for production.
Trace minerals, specifically zinc, can play a role in supporting gut health and reducing the negative effects of dysfunction on the gastrointestinal tract. Zinc plays a role in regeneration of damaged epithelium, improved gut barrier function, improved villus morphology and an altered inflammatory response.
Generally, cattle are provided mineral supplements or fed rations formulated to supply a certain amount of trace minerals or zinc in a given quantity of feed per day. However, during stress events, cattle generally eat less of the supplied feed or supplements. Therefore, stressed cattle are more than likely getting an inadequate supply of zinc. Because of this lowered zinc intake during times of stress, using an improved zinc source becomes increasingly important. Cattle need to get the most out of this inadequate supply of zinc caused by reduced consumption. Improved sources of zinc help maintain intestinal barrier function and preserve the immune system.
What constitutes an improved zinc source? Any zinc source that has covalently bonded chemistry is an improved source. Simplistically, it’s not zinc sulfate or zinc oxide. Improved zinc sources include zinc hydroxychloride and organic zinc sources (proteinate, chelate, amino acid complex, etc.). These zinc sources were developed to have stronger bonds that hold the zinc tighter to its ligand. This allows the zinc to pass through the rumen for absorption in the intestines, where it can then be used for necessary biological purposes by the animal. These improved zinc sources are more expensive than sulfates; however, they deliver better, more predictable nutrition to the animal, which is critical with the near-constant stress cattle encounter. Lost production directly translates to lost dollars.
Zinc source and stress research
As stated earlier, during times of stress, feed intake is often altered and generally reduced. This is clearly the case in times of heat stress when animals simply don’t want to eat. Heat stress or feed restriction is one cause of intestinal dysfunction. Iowa State University research in dairy cows demonstrated that feed-restricted cows consuming zinc hydroxychloride had a 25% increase in intestinal villi height as well as an inflammatory response that responded faster and resolved more quickly than cows consuming zinc sulfate (Figure 1).
Another Iowa State University study evaluating heat stress in dairy cows demonstrated that cows consuming zinc hydroxychloride had better maintenance of the GIT barrier function and a more robust immune response during stress. This response led to a subsequent 14% increase in dry matter intake (DMI) during the heat stress recovery period compared to cows consuming zinc sulfate (Figure 2).
This response should allow an animal to improve its energy balance during and after stress more rapidly. Zinc plays an important role in the animal for intestinal health and immune response. An improved zinc source, like zinc hydroxychloride, has high bioavailability that leads to improved gut integrity and inflammatory responses during times of stress.
Consider the daily stresses cattle go through: heat, weaning, shipping, commingling, etc. Now, consider the nutrition they are getting and the need for improved zinc.