Subclinical mastitis in dairy cows in major milk-producing areas of Sri Lanka: Prevalence, associated risk factors, and effects on reproduction

Abstract

Compared with clinical mastitis, the subclinical form of mastitis (SCM) is more common and thought to cause more economic losses to the dairy industry. The current study aimed to investigate the prevalence, risk factors of SCM, and effects on reproduction of dairy cows in major milk-producing areas of Sri Lanka. A total of 1,357 cows of selected farms in 3 regions were examined in the study. California Mastitis Test was conducted for individual cows, and a score of 2 or more for any quarter without any clinical symptoms and abnormalities in milk was considered as positive for SCM. Samples from infected animals were collected and subjected to bacteriological analysis. A pretested questionnaire was used to collect data on individual cows and herds. Risk factors associated with SCM were analyzed using binary logistic regression in generalized linear mixed models. The effect of SCM on calving to conception interval and days from calving to artificial insemination were analyzed by survival analysis using Cox's proportional hazards regression and Kaplan-Meier survival function estimates, respectively. A Poisson regression model was run to determine the effect of SCM on number of artificial inseminations per conception. The prevalence of SCM was 57.5, 11.8, and 45.5% in the regions A, B, and C, respectively. The most common pathogen was Staphylococcus aureus, with 87.1, 56.5, and 92.3% in the regions A, B, and C, respectively. Logistic regression analysis showed that parity, farming system, milking area, region, and herd significantly affect the prevalence of SCM. Subclinical mastitis during the pre-breeding period was associated with 14% increase in the chance of having a greater number of artificial inseminations per conception. Likewise, median days from calving to artificial insemination was longer in cows with SCM compared with normal cows (79 and 64 d, respectively). Therefore, SCM affected the inseminated proportion of studied cows. However, SCM was not associated with the calving to conception interval. The results revealed that the cow factors and milk hygiene play a significant role in the prevalence of SCM.

Breed and non-genetic risk factors associated with the prevalence of subclinical mastitis in livestock systems of Arauca, Colombian orinoquia

“…In the current study, the EC test detected a cow-level prevalence of SCM similar to that reported in another study [ 34 ] and is considered low compared to other studies in tropical regions [ 8 , 17 , 40 , 44 ]. It is stated that milk from a cow with udder inflammation is a better conductor of electrical waves than milk from a healthy cow [ 45 ].…”

“…In another study, they found that breed and/or crossbreeding was not a risk factor in the prevalence of SCM, while the calving number (primiparous and multiparous), geographic region, and milk production (<10 L, 10–20 L or >20 L) and the region significantly contributed ( p = 0.036) to the risk of SCM. In multiparous cows, the odds of SCM were 2.51 times higher than the odds in first calving cows [ 34 ]. This information differs from the present study, where breed was a risk factor for the prevalence of SCM, with a lower risk factor in the composite breed compared to the taurus-indicus and indicus predominance studied.…”

“…Only cows with functional mammary quarters and without antibiotic treatments during the last 3 months were included in the study. The samples were taken during the rainy period (May to October 2021) and during dry period (November to April 2022), following the recommendations available in the literature [ 2 , 23 , 24 , 34 ]. Mammary quarters were identified, and samples were taken in that order ( Figure 3 ).…”

Characteristics of bacterial contamination of the mammary gland secretion of lactating cows with subclinical mastitis

“…Є суперечливі дані щодо взаємозв'язку СКМ з розвитком неплідності у корів лактаційного періоду (Dahl et al, 2017). За даними Ranasinghe et al (2021), за СКМ у корів зменшується ефективність штучного осіменіння, а тривалість днів періоду від отелення до наступного осіменіння була довшою порівняно і даними контролю (79 і 64 дні відповідно). Натомість Villa-Arcila et al ( 2017) показано, що СКМ, діагностований у перший місяць після отелення, не впливав на тривалість періоду до наступного осіменіння.…”

Efficacy assessment of an intramammary formulation based on soluble polypyrrole in cows with experimentally induced mastitis

“…Mastitis is the most prevalent disease in dairy herds, consisting of mammary gland inflammation that reflects production indices and profitability of agricultural production. These factors are affected by reduced milk production (ADRIAENS et al, 2021), high costs of treatment and prevention (HE et al, 2020), and diminished reproductive performance (DAHL et al, 2020;DALANEZI et al, 2020;RANASINGHE et al, 2021).…”