Effects of added chelated trace minerals, organic selenium, yeast culture, direct-fed microbials, and Yucca schidigera extract in horses: II. Nutrient excretion and potential environmental impact.

This research article examines the hypothesis that an equine diet with added chelated trace minerals, organic selenium, yeast culture, direct-fed microbials (DFM) and Yucca schidigera extract could reduce the excretion of potentially environmentally harmful nutrients. The results showed that these additions did not significantly reduce excretion of most nutrients, and in some cases, increased excretion. However, horses consuming organic selenium had lower fecal and urine selenium concentrations alongside higher fecal potassium concentrations.

Objective and Methodology

• The study aimed to investigate whether horses consuming a specific diet – complete with chelated trace minerals, organic selenium, yeast culture, DFM, and Yucca schidigera extract – would excrete fewer nutrients with a potential environmental impact.
• To test this, the researchers formulated two diets. One included the aforementioned additives (the ADD diet), while the other did not (the CTRL diet).
• The ADD diet featured chelated sources of copper (Cu), zinc (Zn), manganese (Mn), and cobalt (Co) at a 100% replacement rate of the sulfate forms used in the CTRL diet. Organic selenium yeast, DFM, and Yucca schidigera extract were also included in the ADD diet.
• Ten horses were fed these experimental diets for two 42-day periods in a crossover design. During the last two weeks of each period, the researchers collected the horses’ feces and urine for analysis.

Findings

• Welcome news came in the form of no significant differences being found in the concentrations of Cu, Zn, Mn, and Co excreted in the urine due to dietary treatment (P > 0.05).
• No differences were found between the amounts of Cu and Mn excreted in feces based on the diet consumed.
• However, horses consuming the ADD diet were found to excrete more Zn and Co in their feces than those on the CTRL diet (P < 0.003).
• The diet also impacted selenium (Se) excretions in both feces and urine. Horses consuming organic selenium yeast showed decreased Se concentrations in their feces and urine (P < 0.0001).
• The amount of potassium (K) in feces was greater in horses consuming the ADD diet (P = 0.0421).
• No differences were discovered between the amounts of fecal solids, total nitrogen (N), ammonia N, phosphorus (P), total ammonia, and fecal output between the two dietary treatments (P > 0.05).

Conclusion

• The study concluded that adding chelated mineral sources, organic Se yeast, DFM and Yucca schidigera extract to a horse’s diet did not significantly decrease most nutrient concentrations excreted.
• The intake of organic selenium resulted in lower fecal and urine Se concentrations, and higher fecal K concentrations among horses.