How Dietary Zinc Affects Gut Health in Pregnant Cows and Newborn Calves

Greg Howard
20th July, 2024

How Dietary Zinc Affects Gut Health in Pregnant Cows and Newborn Calves

Image Source: Oleksandr P (photographer)

Key Findings

  • The study took place at the University of Pennsylvania and examined the effects of dietary zinc on the microbiota and resistome of gestating cows and their newborn calves
  • High levels of dietary zinc did not significantly affect the diversity or composition of the microbiota in gestating cows or their neonatal calves
  • The diversity and composition of the cow and calf microbiomes changed significantly over time, but these changes were not influenced by zinc supplementation
Zinc is a crucial trace element in the diet of many species, including livestock. While its effects have been extensively studied in growing calves, its influence on the microbiota of gestating cows and their neonatal calves has remained largely unexplored. Understanding these effects is vital for promoting animal health and optimizing feeding practices. A recent study conducted by the University of Pennsylvania aimed to determine how dietary zinc affects the microbiota and resistome (the collection of all antibiotic resistance genes) of gestating cows and their newborn calves[1]. In this study, gestating cows were fed either a standard diet containing 40 parts per million (ppm) of zinc or a high-zinc diet with 205 ppm, from the dry-off period to calving. Fecal samples from the cows were collected upon enrollment and at calving, while samples from the neonatal calves were also gathered. These samples underwent 16S rRNA sequencing to analyze the microbial communities, and a subset was further examined using shotgun metagenomic sequencing to provide a more detailed view of the microbial genes present. The study found that the diversity and composition of the cow and calf microbiomes were significantly altered over time but not by the zinc treatment. Specifically, alpha diversity, which measures the variety of species within a sample, decreased over time. Fourteen genera were found to be significantly more abundant at calving compared to enrollment. Interestingly, the levels of 27 antimicrobial resistance genes increased significantly over time. However, the high-zinc diet did not significantly affect the diversity or composition of the neonatal calf microbiota or its resistome, which was more diverse compared to the cows. These findings indicate that high levels of dietary zinc have a minimal impact on the microbiota diversity and composition of gestating cows and their neonatal calves. This contrasts with previous research on monogastric livestock like pigs and poultry, where zinc supplementation had more pronounced effects. For example, studies have shown that high dietary zinc oxide (ZnO) can alter the gut microbiota composition and increase the abundance of certain microbial taxa in weaning piglets[2][3]. Additionally, high zinc diets in pigs have been linked to changes in microbial functional properties and the selection of antibiotic resistance genes[3]. The minimal impact observed in this study could be due to differences in the digestive systems of ruminants like cows compared to monogastric animals. Ruminants have a more complex stomach structure, which might buffer the effects of dietary changes. Another possibility is that the zinc levels used in the study were not high enough to produce significant changes, although they were considerably higher than the standard dietary recommendations. Moreover, the study's findings align with earlier research suggesting that while zinc is essential for immune modulation and overall health, its effects can vary widely depending on the context. For instance, zinc deficiency in humans and animals can lead to compromised immune function and increased inflammation[4]. However, excessive zinc supplementation can also pose risks, such as environmental concerns and potential toxicity[5]. In conclusion, the University of Pennsylvania study provides valuable insights into the limited impact of high dietary zinc on the microbiota and resistome of gestating cows and their neonatal calves. These findings suggest that while zinc is essential, its supplementation in ruminant diets may not need to be as high as previously thought to achieve desired health outcomes. This could inform more sustainable and effective feeding practices, balancing the need for adequate zinc intake with environmental and health considerations.

NutritionHealthAnimal Science

References

Main Study

1) Effects of dietary zinc on the gut microbiome and resistome of the gestating cow and neonatal calf

Published 19th July, 2024

https://doi.org/10.1186/s42523-024-00326-3

Related Studies

2) Dietary High Zinc Oxide Modulates the Microbiome of Ileum and Colon in Weaned Piglets.

https://doi.org/10.3389/fmicb.2017.00825

3) Concentration and chemical form of dietary zinc shape the porcine colon microbiome, its functional capacity and antibiotic resistance gene repertoire.

https://doi.org/10.1038/s41396-020-0730-3

4) Zinc and its role in immunity and inflammation.

https://doi.org/10.1016/j.autrev.2014.11.008

5) Strategies and challenges to increase the precision in feeding zinc to monogastric livestock.

https://doi.org/10.1016/j.aninu.2017.03.002


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