Relationship of Late Lactation Milk Somatic Cell Count and Cathelicidin with Intramammary Infection in Small Ruminants

Abstract

Late lactation is a critical moment for making mastitis management decisions, but in small ruminants the reliability of diagnostic tests is typically lower at this stage. We evaluated somatic cell counts (SCC) and cathelicidins (CATH) in late lactation sheep and goat milk for their relationship with intramammary infections (IMI), as diagnosed by bacteriological culture (BC). A total of 315 sheep and 223 goat half-udder milk samples collected in the last month of lactation were included in the study. IMI prevalence was 10.79% and 15.25%, respectively, and non-aureus staphylococci were the most common finding. Taking BC as a reference, the diagnostic performance of SCC and CATH was quite different in the two species. In sheep, receiver operating characteristic (ROC) analysis produced a higher area under the curve (AUC) value for CATH than SCC (0.9041 versus 0.8829, respectively). Accordingly, CATH demonstrated a higher specificity than SCC (82.92% versus 73.67%, respectively) at comparable sensitivity (91.18%). Therefore, CATH showed a markedly superior diagnostic performance than SCC in late lactation sheep milk. In goats, AUC was <0.67 for both parameters, and CATH was less specific than SCC (61.90% versus 65.08%) at comparable sensitivity (64.71%). Therefore, both CATH and SCC performed poorly in late lactation goats. In conclusion, sheep can be screened for mastitis at the end of lactation, while goats should preferably be tested at peak lactation. In late lactation sheep, CATH should be preferred over SCC for its higher specificity, but careful cost/benefit evaluations will have to be made.

Milk Pathogens in Correlation with Inflammatory, Oxidative and Nitrosative Stress Markers in Goat Subclinical Mastitis

“…The high percentage of PMN (45–74%) from the total somatic cells in mastitis-free goats suggests that these animals could be more resistant to intramammary infections when compared with cows or sheep [ 33 ]. Nonetheless, besides the presence of an infection in the udder, there are also several other non-infectious factors that influence SCC in goats [ 34 , 35 ]. Among these factors are the stage of lactation, parity, breed, milking time, type of milking, feed, farming system, seasonality or stress [ 29 , 34 , 36 , 37 , 38 ].…”

Potential Novel Biomarkers for Mastitis Diagnosis in Sheep

“…Therefore, investigation of cathelicidins in milk with simultaneous SCC improves detection of subclinical mastitis. Puggioni et al [107] evaluated SCC and CATH in late lactation sheep milk for their relationship with intramammary infections. They demonstrated that CATH has a higher specificity than SCC (82.92% vs. 73.67%), but both have similar sensitivity, total about 91.8%.…”

Relationship of Production Traits and Udder Morphometry with Somatic Cell Count in Zaraibi Goats

“…In both small and large dairy animal species, mastitis and high somatic cells in milk have negative effects on milk production and quality with major economic consequences in the dairy industry (Novac and Andrei, 2020). Udder health monitoring plans and modern management strategies could contribute in lessening mastitis impact (Puggioni et al, 2020). In the dairy goat herds, the mastitis represents a major constraint implicating adverse effects on milk yield and composition, that commonly can reach high prevalence, being more than 30% (Quintas et al, 2017).…”