Masters Theses

Date of Award

8-2024

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Kyle J. McLean

Committee Members

Elizabeth A. Shepherd, Daniel J. Mathew, Elizabeth A. Eckelkamp

Abstract

Dairy cows experience the most physiological stress during the periparturient period which can be linked to poor reproductive performance. By-products of this physiological stress, specifically ROS, can induce cellular damage during early embryonic development and pregnancy establishment. Most pregnancy loss occurs during the first 14 days post-breeding during the early embryonic developmental period. Supplementation of organic sources of zinc, copper, and manganese can improve the function of superoxide dismutase (SOD), which may impact fertility through immunological pathways. We hypothesized that trace mineral source would impact maternal immune environment which may lead to a better understanding of early embryonic loss. Lactating Holstein cows (n = 77) were assigned one of two sources of zinc, copper, and manganese: 1) Metal Methionine Hydroxy Analogue Chelate or 2) Inorganic Trace Mineral (ITM) at least 30 d pre-breeding and up to 65 d post breeding. All cows underwent a double Ovsynch protocol and were artificially inseminated (d 0). Humoral immunological status was assessed via immunity score within serum samples (d 0 and 7). Cytokine concentrations were assessed in vaginal flush samples (d 0 and 7). Ultrasonography (d 35) was utilized for pregnancy diagnosis, dividing cows into either pregnant or open groups. Progesterone analysis from d 21 plasma was used to categorize open cows as either non-pregnant or early embryonic loss. Body weight and body condition score were taken every 30 days. Analyses were conducted in SAS 9.4 using PROC GLIMMIX to determine differences in response variables. Post-breeding BW were lower in EEL cows receiving ITM and NP cows receiving MMHAC (P = 0.03). On day 0, NP cows tend to have higher concentrations of TNF-α (P = 0.09) and pregnant cows had increased concentrations of VEGF-A (P = 0.03). Cows treated with ITM had increased concentrations of IL-10 (P = 0.04) on d 0 and IL-1β (P = 0.04) on d 7. While there were no differences in systemic immune status, the differences in cytokine concentrations indicated immunological changes associated with pregnancy outcome and treatment type allowing for further elucidation of immunological changes associated with mineral supplementation and reproductive performance.

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Dairy Science Commons

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