Cattle study shows improved bioavailability of zinc when supplemented with hydroxy trace minerals
Nutrient availability is a major point of focus for cattle feeds, especially feed additives like trace minerals. When evaluating trace minerals, the product’s value can be defined based on how well the source optimises animal performance and well-being while limiting unwanted reactions and excessive cost. Optimised bioavailability is the foundation of an effective trace mineral supplementation program – without it, the trace mineral source in question falls short of achieving ideal results.
Ruminants pose a unique challenge to trace mineral bioavailability given the anatomy of their digestive systems. It is important for a trace mineral to withstand degradation in the upper GI tract (rumen) to preserve the trace mineral’s bioavailability when it reaches the intestinal tract. This is where actual absorption of essential trace minerals occurs, provided that the trace metal is in a form that allows for its absorption across the intestinal wall. Once the metal contained within the trace mineral has been absorbed, it is now available to the animal to support numerous physiological functions such as immune function, tissue integrity (hoof and skin), reproduction, growth, productivity, etc.
Measuring zinc absorption and retention
Research in cattle has helped to shine a brighter light on how various sources of zinc impact trace mineral bioavailability, and (by extension) beef cattle performance. A recent study (2017) conducted at the University of North Carolina compared a hydroxy trace mineral source of zinc with a sulphate source to measure differences in apparent bioavailability and faecal excretion.
Researchers evaluated 16 yearling steers (eight Angus and eight Simmental), by first feeding a diet without any supplemental zinc to induce a partial zinc depletion before the start of supplementation. Steers were then randomly assigned to diets supplemented with either 25 ppm of zinc from hydroxy trace minerals (Selko® IntelliBond® Z) or 25 ppm of zinc from zinc sulphate. The depletion period allowed for the best assessment of bioavailability because it ensured the operation of absorptive and excretory pathways to maximise trace mineral uptake.
Following a 32-day repletion period, researchers found similar dry matter intake, total zinc intake and urinary excretion of zinc between the two groups (p > 0.26). However, plasma zinc levels were increased by 0.14 mg/dL in the hydroxy-fed cattle over those fed zinc sulphate (p = 0.03). Notably, faecal zinc excretion was significantly lower in cattle fed hydroxy trace minerals than those fed zinc sulphate (p = 0.01). Overall, apparent absorption and retention of zinc was significantly greater for the hydroxy trace minerals group than their peers supplemented with zinc sulphate.
About Trouw Nutrition Trouw Nutrition, a Nutreco company, is a global leader in innovative feed specialties, premixes and nutritional services for the animal nutrition industry. It provides products, models and services to boost productivity and support animal health through all life stages. With unique, species-specific solutions, Trouw Nutrition has been meeting the needs of farmers and home-mixers, feed producers, integrators and distributors since 1931. Headquartered in the Netherlands, the company has locations in 28 countries and employs approximately 8,000 people.
