Epidemiological evaluation of subclinical mastitis of dairy cows in Greece

Abstract

Subclinical mastitis, diagnosed by elevated somatic cell count (SCC) in milk, is an important monitoring parameter of dairy cows’ udder health, related to their productivity and welfare. The present retrospective study aims to evaluate the epidemiology of subclinical mastitis (SCM) among the 37 herds of the Holstein Association of Greece participating in the milk quality recording system “ΙΩ”, from the start of 2015 until the end of 2018. The herds’ inclusion criterion was the consistency of monthly SCC recording throughout at least one full year between 2015 and 2018, with a maximum interval of 61 days between two consecutive monthly SCC recordings. Twenty-six herds (8630 cows) in 2015, thirty herds (10763 cows) in 2016, thirty herds (10945 cows) in 2017 and twenty-six herds (9597 cows) in 2018 were included. The prevalence of SCM and chronic SCM, the incidence rate of new cases of SCM, as well as the average somatic cell score and bulk tank milk SCC were determined for each of the four years. The results indicate a progressive deterioration of udder health from the onset of the cow’s productive life until culling. A year-over-year increase in the number of cows with subclinical mastitis led to an overall SCM prevalence of 34.5%, chronic SCM prevalence of 26.9% and a bulk tank milk SCC of 463000 cells/mL, in 2018. The average somatic cell score, a base 2logarithm of individual cow’s SCC, was found persistently above the subclinical mastitis indicative cut-off in all four years, with a peak in 2018. At herd level, the incidence rate of new SCM cases was 12 new cases / 100 cows / month; the highest incidence rate was observed in the early lactation stage group (1-60 days-in-milk), in all four years, reaching a peak of 31 new cases / 100 cows / month, in 2018. In 2018, prevalence of heifers’ SCM and chronic SCM was23.4% and 16.9%, respectively. Despite the adequate average 305-days milk yield (9608 kg in 2018), the results were indicative of poor udder health status, pointed out by reduced duration of cows’ productive life (less than 3 lactations)and lower milk quality (elevated SCC). The severity and wide spreading of subclinical mastitis in Greek dairy herds highlights the necessity of a national mastitis control program, aiming to improve the productive efficacy, management decisions accuracy and quality of produced milk.

Automatic Milking in Greece: First Insight into Udder Health of Dairy Cows

“…Number of NewELSCC cows was high in the fresh cows' stage and both in cows' and heifers' groups. Mean proportion of ELSCC cows in three of the four AMS farms, presented in Table 2, was higher than the mean of conventional farms presented by Themistokleous et al (2019). In the present study, the cut-off value for a cow to be classified as ELSCC was 150,000 cells/mL, instead of 250,000 cells/mL used in Themistokleous et al (2019).…”

“…Udder health and traits of cow productivity in the four robotic farms enrolled in this study were better than farms with conventional milking systems reported by Themistokleous et al (2019). In 2021, mean cow 305-days milk yield in these AMS farms was 17% (1,631 kg) higher than conventional farms in 2018.…”

“…Mean proportion of ELSCC cows in three of the four AMS farms, presented in Table 2, was higher than the mean of conventional farms presented by Themistokleous et al (2019). In the present study, the cut-off value for a cow to be classified as ELSCC was 150,000 cells/mL, instead of 250,000 cells/mL used in Themistokleous et al (2019). Also, daily milking data from the robots provide a more sensitive method, compared to the once-a-month sampling method in conventional farms, partially explaining this result.…”

“…Mean SCC of herd, lactation period and lactation stage groups, presented in Table 1, was lower than the somatic cell scores' equivalent of the respective groups in conventional farms (Themistokleous et al, 2019). In three of the four farms mean cow SCC increased at herd level from 2020 to 2021.…”

“…Neijenhuis et al (2010) supported that herds with poor udder health before the conversion to AMS were less likely to have good udder health after this change. In a four-year study of dairy farms with conventional milking systems in Greece, Themistokleous et al (2019) reported poor udder health, affecting cows' productive longevity and milk quality. These facts underlined the necessity of an investigation of udder health traits in Greek dairy farms with AMS.…”