Combined effect of mastitis and parity on pregnancy loss in lactating Holstein cows

Mohammad O Dahl; Albert De Vries; Klibs N Galvão; Fiona P Maunsell; Carlos A Risco; Jorge A Hernandez

doi:10.1016/j.theriogenology.2019.12.002

Combined effect of mastitis and parity on pregnancy loss in lactating Holstein cows

Theriogenology. 2020 Feb:143:57-63. doi: 10.1016/j.theriogenology.2019.12.002. Epub 2019 Dec 9.

Authors

Mohammad O Dahl¹, Albert De Vries², Klibs N Galvão³, Fiona P Maunsell⁴, Carlos A Risco⁵, Jorge A Hernandez⁶

Affiliations

¹ Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, 32611-0910, USA; Department of Internal and Preventive Medicine, College of Veterinary Medicine, University of Mosul, Mosul, 41002, IRAQ.
² Department of Animal Sciences, University of Florida, Gainesville, 32611-0910, USA.
³ Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, 32611-0910, USA; D. H. Barron Reproductive and Perinatal Biology Research Program, University of Florida, Gainesville, FL, 32610, USA.
⁴ Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, 32611-0910, USA.
⁵ Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, 74078-2005, USA.
⁶ Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, 32611-0910, USA. Electronic address: hernandezja@ufl.edu.

PMID: 31837631
DOI: 10.1016/j.theriogenology.2019.12.002

Abstract

The main objective of this study was to examine the combined effect of mastitis and parity on pregnancy loss (PL) in lactating Holstein cows. A secondary objective was to estimate the cost of mastitis including that of PL attributable to mastitis. A total of 1,774 lactation periods from 1,047 Holstein cows with different parities from one dairy farm were included in a matched case-control study. All study cows were diagnosed pregnant by transrectal ultrasonography on day 33 after timed artificial insemination (TAI). Case cows (n = 222 lactations) were those later diagnosed non-pregnant by transrectal palpation on day 47 or 75 after TAI. Control cows (n = 1,552 lactations) were those confirmed pregnant by transrectal palpation on day 75 after TAI. Case cows were matched with eligible controls according to year of calving and calving-to-conception interval (CCI) ± 3 days. Cows with different parities were classified as exposed to subclinical mastitis (somatic cell score (SCS) > 4.5 in at least one Dairy Herd Improvement Association (DHIA) test day) or clinical mastitis (with or without evidence of subclinical mastitis) during two exposure periods: 1-42 days before breeding or 1-75 days during gestation (1 to PL diagnosis day in case cows, or 1-75 day in control cows). Conditional logistic regression was used to model the odds of PL as a function of previous exposure to mastitis in different parities. Cost of PL attributable to mastitis ($/case) among cows with mastitis was estimated based on attributable risk calculated in the epidemiologic analysis. We observed a higher than expected combined effect between exposure to mastitis (subclinical or clinical) before breeding and parity 3 or ≥ 4, and during gestation and parity ≥ 4 on PL. The cost of PL attributable to mastitis was highest ($196/case) in cows in parity ≥ 4 affected with clinical mastitis during gestation. Overall, study results indicate the impact of mastitis on PL is higher in older cows (parity ≥ 3). Dairy farmers and attending veterinarians can consider the combined effect of mastitis and parity when evaluating causes for PL and strategies for optimizing reproductive performance in dairy cows.

Keywords: Dairy cows; Mastitis; Parity; Pregnancy loss.

MeSH terms

Abortion, Veterinary / etiology*
Animals
Case-Control Studies
Cattle
Female
Lactation*
Mastitis, Bovine / complications*
Parity*
Pregnancy
Risk Factors