In dairy cattle, mastitis is a disease of the mammary gland caused by pathogens, such as bacteria, viruses, fungi, and algae. Mastitis causes economic losses to dairy farms, as well as public health concerns. The reproductive efficiency of commercial dairy herds has important implications for the economic success of dairy operations and is tightly associated with the health status of cows. Mastitis has previously been linked with decreased fertility of dairy cows, but the effect of specific pathogens on the severity of this fertility reduction is still unclear. In this study, cows diagnosed with mastitis caused by major pathogens (Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, Klebsiella spp., Mycoplasma spp., and environmental Streptococcus) needed more artificial inseminations (AI) than cows with mastitis caused by minor pathogens (Coagulase-negative Staphylococcus and Corynebacterium spp.) and healthy cows. Cows diagnosed with mastitis, independent of what pathogen was causing mastitis, had more days open compared with non-mastitic cows. The percentage of cows that successfully established pregnancy at the first AI was greater in the control group compared with cows in the major pathogens group, but not significantly different from cows in the minor pathogens group. Pregnancy loss was lower in the control group compared with that in the major pathogens group; however, there was no difference upon comparison with the minor pathogen group. Mastitis caused by gram-negative bacteria decreased percentage of pregnancy per first AI and increased days open and pregnancy loss compared with those in the control group. Cows with mastitis caused by gram-positive bacteria also had increased days open when compared with control cows. This study shows that different mastitis-causing bacteria can affect the fertility of cows differently. Mastitis events caused by major pathogens and gram-negative bacteria were associated with the greatest decrease in reproductive efficiency.


Helio Langoni -Sanitarist veterinary, graduated in Veterinary Medicine by Sao Paulo State University – UNESP (1976), specialization in Public health by University of Sao Paulo – USP (1980), and PhD in Virology by The University of Veterinary Medicine Hannover (1982-1985). Senior internship in University of Wisconsin, USA. Actually, is titular retired professor of Faculty of Veterinary Medicine and Animal Science, UNESP, Botucatu, Sao Paulo. Permanent external professor of Animal Science program in University of Vila Velha-UVV. Was president of Brazilian Council of Milk Quality (CBQL). Brazilian representative in the International Society for Animal Hygiene (ISAH). Scientific reviewer of 24 periodicals. Has experience in Preventive Veterinary Medicine and Public Health, with emphasis in zoonosis, acting mainly in the following subjects: mastitis and milk quality, leptospirosis, toxoplasmosis, leishmaniosis, rabid, and another zoonosis. Is the editor-in-chief of the journal Revista Veterinaria e Zootecnia.