Effect of microbiome on zinc and copper absorption in the gastrointestinal tracts of the American Bison herds on the Fort Peck Indian Reservation

Abstract

On the Fort Peck Reservation bison are separated into two pastures: a genetically pure bison herd (cultural herd) and a non-genetically pure bison herd with cattle genes (business herd). Vital nutrients such as zinc and copper may be lacking in their diet and those nutrients may not be absorbed in sufficient amounts. Ussing chamber studies using stomach tissue measure the absorption of these nutrients. Trace metals of copper and zinc are stored in the liver and measurements of those levels determined deficiencies in the animals. In addition, in ruminants such as the bison, the microbiota play a critical role in nutrient digestion and energy availability to the host. To characterize the bison gastrointestinal microbiome composition, we collected gastrointestinal samples from different stomach compartments from bison in cultural and business herds. Trace metal analysis using atomic absorption spectroscopy was also performed for liver samples collected from the two herds. Spectroscopic analysis revealed essential trace metals to be deficient between the two herds and to be similar between genders. Copper levels were substantially lower in both herds (7.8± 0.5 ppm for the cultural herd and 6.7±0.8 for the business herd, where normal levels are 87.5±16). Zinc values were also substantially lower at 30.57±0.5 for the cultural herd and 25± 2.6 for the business herd, where normal levels are 112.5± 12. Ussing Chamber experiments performed on reticulum and rumen tissues collected from both cultural and business herds identified significant absorption of Isc of zinc (250±35 mAmp) and Isc of copper (278±39 mAmp). The second stomach had similar values (223±30 mAmp) Isc of copper (258 uAmp ±29 for zinc). Bacterial community analysis using 16S rDNA sequencing identified significant microbial population changes across the gastrointestinal tract of bison. The reticulum, rumen and omasum displayed similar microbial community compositions. The aomasum was different from the 3 rumen compartments and the proximal intestine and colon samples. The proximal colon microbial community composition was unique and was different from all rumen and colon samples. The distal and proximal colon samples were similar to each other but, were significantly different from all other samples. Although gut location was the largest driver of microbial community differences, microbial community differences were also identified based on herd and gender. Current analysis shows that animals that are deficient in copper or zinc or on different pastures with different diets the differences in the microbiota may be insignificant. In conclusion, the bison are somewhat deficient in Cu and Zn but have a great capacity to absorb these trace metals. The lack of these trace metals therefore comes from a lack of these metals in their diet and may affect microbial function and nutrient digestion leading to less energy available to the host. United States Department of Agriculture Grant This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.