PREVALENCE AND RISK FACTORS OF SUB-CLINICAL MASTITIS IN LACTATING BLACK BENGAL GOATS DETECTED BY USING INDIRECT AND DIRECT METHODS OF SOMATIC CELL COUNT IN BANGLADESH

Abstract

Background: Sub-clinical mastitis (SCM) has been reported to be more widely prevalent than clinical mastitis (CM) in lactating dairy animals and associated with heavy economic losses with changes in quality and quantities of milk worldwide. Several indirect and direct methods of Somatic cell count (SCC) are used to detect SCM in dairy animals but reports on their comparative evaluation are very limited in inland literature especially in goats. Objective: This study was undertaken to evaluate the comparative efficacy of different indirect tests with direct microscopic milk SCC (DMMSCC) to detect the prevalence of SCM in lactating goats of smallholder and organized goat farms with their associated risk factors in Bangladesh Materials and Methods: Milk samples were collected aseptically from both halves (n = 140) of each of 70 apparently healthy lactating Black Bengal goats (BBG) at different stages of lactation from Rajshahi Goat Development Farm (RGDF; n = 20) and smallholder farms (n = 50) of adjacent villages of the Bangladesh Agricultural University (BAU) campus, Mymensingh during the period from July 2010 to June 2011. The White side test (WST), Surf field mastitis test (SFMT), California mastitis test (CMT) and DMMSCC were used to diagnose the SCM in milk samples as per instructions of the diagnostic methods. The potential risk factors associated with the prevalence of SCM were analyzed using multiple regression and uni-variable logistic regression analysis. Results: The overall an average of 30.0% prevalence of SCM was recorded in this study irrespective of the method used. The comparative evaluation of four milk screening tests for SCM showed higher efficacy with the WST (32.0%) and CMT (31.43%) in comparison to SFMT (28.0%) and DMMSCC (26.0%). The significantly higher prevalence of SCM was recorded in late lactation (37.90%), long teat (44.40%) and shortest teat end to floor distance (33.30%) in lactating goats. Uni-variable logistic regression analysis depicted that SCM was more prevalent in does with increased age, parity and during winter season. Conclusions: This study recorded comparatively higher efficacy with WST and CMT in comparison to SFMT and DMMSCC to detect SCM in lactating goats. It may be concluded that either WST or CMT along with bacterial culture of milk samples are required for accurate diagnosis of SCM in goats. Moreover, it may also be suggested to test the milk samples simultaneously of both the haves of lactating goats by using a single test to compare their results between the half for the detection of SCM. Some risk factors are found associated with the prevalence of SCM in goats and therefore, effective measures need to be required to improve these risk factors in both goat development farm and smallholder farm levels to control caprine mastitis in Bangladesh. Keywords: Black Bengal goats, Sub-clinical mastitis, Prevalence, Indirect tests, Direct somatic cell count, Goat farm, Smallholder farmers, Risk factors