Health events during the first year of life can alter the uterine environment and ovarian reserve in cycling heifers

Authors: Snider, Alexandria - Alex; Oliver, William; Crouse, Matthew; Cushman, Robert - Bob

Submitted to: Society for the Study of Reproduction Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 10/2/2021
Publication Date: 12/15/2021
Citation: Snider, A.P., Oliver, W.T., Crouse, M.S., Cushman, R.A. 2021. Health events during the first year of life can alter the uterine environment and ovarian reserve in cycling heifers [abstract]. Society for the Study of Reproduction Annual Meeting, December 15-18, 2021, St. Louis, Missouri. Poster P335.

Interpretive Summary:

Technical Abstract: During the first year of life, developing heifers may experience increased stress resulting from nutritional status of the dam, environmental stresses, or potential health events such as foot rot, pneumonia, or bovine viral diarrhea. While heifers may overcome these acute illnesses and appear to be healthy going into their first breeding season, some heifers may remain open at the end of the breeding season due to the stresses experienced during their development. Thus, the objective of this retrospective analysis was to determine if health events during the first year of life can alter the uterine environment. We hypothesized that heifers that experienced a health event during the first year of life will have altered cytokine profiles in the uterus. Angus heifers from a previous study (n = 30) were synchronized utilizing a select-synch protocol and the reproductive tracts were collected 14 days after estrus onset. The uterus was flushed with 20mL PBS through the uterus by inserting a blunt needle through the tip of the horn contralateral to the corpus luteum and massaging the PBS through the uterine body out the tip of the horn ipsilateral to the corpus luteum. Recovered PBS was then stored at -80°C for further cytokine analysis. Ovarian surface antral follicles were counted, and ovaries were fixed and stained to determine microscopic follicle numbers. Previous health events were determined based on whether medical treatment was administered to heifers (n=23 no treatment; n= 7 treatment). The data was analyzed utilizing the MIXED procedure in SAS with health status as a main effect and P < 0.05 set as the threshold for significance. From the 15 cytokines analyzed, there was a significant increase (P = 0.02) in IL-10 in the uterine luminal fluid (ULF) of heifers with a previous health event. A tendency was also observed for IP-10 (P = 0.06) in the ULF of heifers with a previous health event. While no difference was observed in total follicle counts based on health status, a negative correlation (P < 0.05) was observed for uterine IP-10 and surface antral follicle counts. Secondary follicles were also negatively correlated (P < 0.05) with uterine IP-10 concentrations. Based on these data, a health event within the first year of life impacts the uterine cytokine profile compared to heifers that did not experience a health event. Increased uterine IP-10 correlates to decrease total surface antral follicle counts and secondary follicles. These two cytokines have an important role in regulating the adaptive immune response, with IP-10 increasing natural killer cells and T-cells to an area with increased inflammation. The other cytokine, IL-10 is important for reducing the pro-inflammatory response and has been shown to be elevated during an inflammatory event. Further studies are required to determine if this altered uterine cytokine profile leads to decreased conceptions rates. USDA is an equal opportunity provider and employer.