Pathogen-specific production losses in bovine mastitis

Abstract

Reduction in long-term milk yields represents a notable share of the economic losses caused by bovine mastitis. Efficient, economic, and safe measures to prevent these losses require knowledge of the causal agent of the disease. The aim of this study was to investigate pathogen-specific impacts of mastitis on milk production of dairy cows. The materials consisted of milk and health recording data and microbiological diagnoses of mastitic quarter milk samples of 20,234 Finnish dairy cows during 2010, 2011, and 2012. The 6 most common udder pathogens were included in the study: Staphylococcus aureus, non-aureus staphylococci (NAS), Escherichia coli, Corynebacterium bovis, Streptococcus uberis, and Streptococcus dysgalactiae. We used a 2-level multilevel model to estimate curves for lactations with and without mastitis. The data on lactation periods to be compared were collected from the same cow. To enable comparison among lactations representing diverse parities, the estimated lactation curves were adjusted to describe the cow's third lactation. Mastitis caused by each pathogen resulted in milk production loss. The extent of the reduction depended on the pathogen, the timing of mastitis during lactation, and the type of mastitis (clinical vs. subclinical). The 2 most commonly detected pathogens were NAS and Staph. aureus. Escherichia coli clinical mastitis diagnosed before peak lactation caused the largest loss, 10.6% of the 305-d milk yield (3.5 kg/d). The corresponding loss for Staph. aureus mastitis was 7.1% (2.3 kg/d). In Staph. aureus mastitis diagnosed between 54 and 120 d in milk, the loss was 4.3% (1.4 kg/d). The loss was almost equal in both clinical and subclinical mastitis caused by Staph. aureus. Mastitis caused by Strep. uberis and Strep. dysgalactiae resulted in losses ranging from 3.7% (1.2 kg/d) to 6.6% (2.1 kg/d) depending on type and timing of mastitis. Clinical mastitis caused by the minor pathogens C. bovis and NAS also had a negative effect on milk production: 7.4% (2.4 kg/d) in C. bovis and 5.7% (1.8 kg/d) in NAS when both were diagnosed before peak lactation. In conclusion, minor pathogens should not be underestimated as a cause of milk yield reduction. On single dairy farms, control of E. coli mastitis would bring about a significant increase in milk production. Reducing Staph. aureus mastitis is the greatest challenge for the Finnish dairy sector.

Differential somatic cell count as an additional indicator for intramammary infections in dairy cows

“…The role of minor pathogens in causing IMI and the subsequent effect on the SCC and production have been extensively debated in the literature (e.g., Harmon, 1994;Pyörälä and Taponen, 2009;Schukken et al, 2009;De Vliegher et al, 2012), and it is unclear when minor pathogens constitute a problem due to the highly variable pathogenicity within this group. A recent study showed that minor pathogens can impair the performance of dairy cows, for example, causing production loss (Heikkilä et al, 2018). Nonetheless, because the presence of minor pathogens may not always be associated with increased SCC (e.g., Figure 2), DSCC might be a useful addition for indicating problems with minor pathogens.…”

The effect of intramammary infection in early lactation with non-aureus staphylococci in general and Staphylococcus chromogenes specifically on quarter milk somatic cell count and quarter milk yield

“…As a group, the NAS are the most prevalent (ranging from 9.1 to 16.6% of milk samples) causative agents of IMI in dairy cows in many regions (Wilson et al, 1997;Pitkälä et al, 2004;Tenhagen et al, 2006), and are typically more isolated from subclinical than from clinical cases of mastitis (Persson Waller et al, 2011;Heikkilä et al, 2018). The relevance of NAS IMI with regard to the effect on milk production in affected The effect of intramammary infection in early lactation with non-aureus staphylococci in general and Staphylococcus chromogenes specifically on quarter milk somatic cell count and quarter milk yield D. Valckenier, 1 S. Piepers, 1 A.…”

“…Part of the contradiction can be attributed to differences in the length of the follow-up period, breed, parity, diagnostic methods, and definition of IMI status among the studies. More recent studies, considering only heifers (Valckenier et al, 2019) or cows of all parities (Tomazi et al, 2015;Heikkilä et al, 2018), still consider NAS (as a group) to be minor pathogens, only slightly elevating the quarter milk SCC (qSCC) in case of subclinical mastitis, and with little or no effect on the quarter milk yield (qMY).…”

Cross-sectional study on the prevalence of contagious pathogens in bulk tank milk and their effects on somatic cell counts and milk yield

“…The need to know the health status of dairy herds is essential to increase herd efficiency and sustainability (Pulina et al 2017). Among the diseases affecting dairy cows, mastitis is still the most important one significantly affecting the profits of dairy farmers (Summer et al 2015;Goncalves et al 2018;Heikkil€ a et al 2018). Furthermore, this aspect is important when protocols based on a prudent use of antibiotics should be applied on such as selective dry cow therapy (Trevisi et al 2014;Zecconi, Sesana, et al 2018).…”