Unraveling the role of zinc transporters in healthy and respiratory disease challenged feedlot steers: Insights into zinc status assessment
Notice bibliographique
Résumé
Zinc (Zn) is an essential micronutrient that impacts all aspects of immune function and overall health in humans and animals, particularly in cattle. In calves, marginal Zn deficiency can lead to suboptimal growth and increased susceptibility to respiratory disease. However, in contrast to other trace minerals such as copper, tissue and plasma concentrations of Zn do not change readily in conditions of supplementation or marginal deficiency. Therefore, this thesis explores the expression dynamics of the Zn transporter machinery in bovine immune cells under homeostasis, in conditions of high Zn supplementation or during a respiratory infection in feedlot steers. Chapter 2 provides an in-depth exploration of Zn homeostasis, including its impact on immune function, metabolism, Zn transporters, and metallothioneins (MTs) in healthy and sick animals, with a focus on cattle experiencing bovine respiratory disease (BRD). In addition, this section covers the impact of Zn on the severity of BRD, commonly caused by a combination of viral and bacterial pathogens, such as bovine respiratory syncytial virus (BRSV), followed by secondary bacterial pathogens such as Mannheimia haemolytica (MH). In the first study (Chapter 3), eighteen Angus crossbred steers (261 ± 14 kg) were blocked by body weight and randomly assigned to two dietary treatments: no supplemental Zn (control) or supplemented with 150 mg ZnSO4/kg DM (HiZn). The analyzed Zn concentration for the control diet was 58 mg Zn/kg DM, and HiZn was 207 mg Zn/kg DM. This study investigated the effects of dietary Zn supplementation on labile Zn concentration and Zn transporter gene expression in circulating immune cells isolated from healthy feedlot steers. Labile Zn levels (based on FluoZin-3 fluorescence) in innate and adaptive immune cells were significantly altered in steers fed the HiZn diet. Steers supplemented with the HiZn diet had modulated Zn transporter expression in sort-purified resting immune cells, particularly in B cells, and CD8 and CD4 T cells. The second study evaluated the effects of a BRSV-MH coinfection on the gene expression of Zn transporters and MTs in whole blood (WB), cells from the nasopharynx (NPS), and bronchoalveolar lavages (BAL). A secondary objective was to observe the impact of intranasally treated Zn and vitamin A (VA) on the expression of these transporters. Forty-eight Angus-cross steers (333 ± 4.2 kg) were randomly assigned into four intranasal (IN) treatment groups (n = 12/group); control, IN VA, IN Zn, or IN VA and Zn combined (VA/Zn). Steers were trucked for 6 h on d (-1), aerosol inoculated with a BRSV on d 0, treated with IN treatments on d 4, followed 24 h later by intratracheal infection with MH. WB and NPS were collected on d 0, 5, and 7, and BAL was collected on d 0 and 7. Steers infected with BRSV infection had higher expression of most ZIPs and ZnTs in NPS by d 5, while in the peripheral blood compartment, expression patterns varied. MH infection downregulated the expression of most ZIPs and ZnTs in NPS and increased most ZIPs in WB and BAL. Interestingly, MT1A and MT2A expression decreased in IN Zn-treated steers on d 5 of viral infection (24 hours after IN treatment). This study highlights the impact of respiratory infection on the local and systemic expression of Zn transporter machinery and suggests that evaluation of Zn transporter expression may be useful to assess Zn status in BRD-affected animals. In conclusion, the findings from both studies highlight the significance of maintaining optimal Zn intake and status for proper immune function and provide insights into Zn deficiency, supplementation, and their impact on immune responses in cattle experiencing BRD. While the studies presented in this thesis offer valuable insights into the effect Zn supplementation has on labile Zn concentration and Zn transporter gene expression in both healthy cattle and cattle experiencing BRD, further research is needed to explore the potential of labile Zn, as well as Zn transporter and MT gene expression for better representation of an animal's Zn status. Such research would greatly benefit the feedlot industry in identifying proper Zn diet requirements for animals responding to respiratory disease, ultimately the negative consequences seen in BRD cases in feedlot settings.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».