Assessment of the Prevalence of Subclinical Mastitis in Dual Purpose Livestock System of Colombian Orinoquia: On-Farm Diagnostic Tests Comparison

Abstract

The assessment of the prevalence of Subclinical Mastitis (SCM) in dairy farms is essential to validate the health status of the mammary gland. The aim of the study was to assess the prevalence of SCM in dual purpose livestock systems in Arauca, Colombian Orinoquia, through the analysis of the values found by the field diagnostic tests California Mastitis Test (CMT) and Electric Conductivity (EC). Milk samples were taken from the individual mammary quarters of 481 cows. The general prevalence, per affected room and the total number of rooms was determined according to the values obtained for each test using two methods of analysis. An ANOVA was performed to determine the difference between prevalence’s, a correlation analysis, and an analysis of sensitivity and specificity. The general prevalence was similar between the tests (CMT = 31.4%; EC = 29.7%) (p > 0.05). The prevalence of the total quarters was lower with EC (11.3% vs 14.2%) (p < 0.05). The correlations between tests were significant, but with low values (rs = 0.20-0.25). CMT and EC test concordance showed a sensitivity between 0.35-0.45 and a specificity of 0.75-0.90. The two tests showed positive results in detecting the same animals with or without the presence of the infection, although some animals that were positive for one test were not positive for the other test. The test EC classified animals and their quarters as SCM positive or negative in a more similar way to that obtained with CMT. The two diagnostic tests showed a general low prevalence of SCM in the livestock systems evaluated.

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

“…Milking is done by hand (once a day), with the calf’s presence and is done under covered cowshed or in open environments. The calf suck before milking to stimulate milk let-down and then suck after milking; this is a normal handling in tropical dairy production [ 29 ]. At the time of milking, the udder washing of the cows is not observed.…”

“…Prevalence is an indicator of existence or “stock”, as it considers all present cases, whether new or old, and refers to the number of cases that a disease or infectious event occurs in a given place and time [ 38 ]. The cow-level prevalence (with at least one affected mammary quarter), total mammary quarters prevalence, and mammary quarters prevalence by position were processed according to the following mathematical formulas [ 29 , 39 , 40 ]: Cow-level prevalence = (Number positive cows/Total number sampled cows) x 100 Prevalence at the level of total mammary quarters = (Total number positive mammary quarters/Total number sampled mammary quarters) x 100 Prevalence at the level of the mammary quarter by position = (Total number positive mammary quarters per position/Total number mammary quarters per position) x 100 …”

“…The udder health status of milking animals is unknown, due to the scarce reports available in the area. Therefore, the practical applicability of EC test on-farm allows rapid diagnosis of SCM without the need for expensive and time-consuming microbiological culture [ 29 ]. The risk factors study for the SCM prevalence allows us to measure the presence of an animal health problem in an area with a livestock attitude [ 8 ].…”

Environmental and Breed Risk Factors Associated with the Prevalence of Subclinical Mastitis in Dual-Purpose Livestock Systems in the Arauca Floodplain Savannah, Colombian Orinoquia

“…In most farms, animal feeding is based on extensive grazing systems with grasses, mainly Brachiaria decumbes and Brachiaria arrecta. On some farms, sodium chloride (white salt) is provided, and mineralized salts are provided to a lesser extent [36]. The destination of the milk is for self-consumption, homemade or artisan production, reception in collection centers, or direct sale to consumers.…”

“…Therefore, microbiological examinations for the detection of SCM are difficult to perform. The practical applicability of CMT on the farm allows rapid diagnosis of SCM without the need for costly and time-consuming microbiological culture [36]. The study of risk factors for the prevalence of SCM allows us to measure the presence of an animal health problem in an area with a livestock attitude [19].…”