Milk NAGase, CMT and antitrypsin as indicators of caprine subclinical mastitis infections

Bayesian latent class evaluation of three tests for the screening of subclinical caprine mastitis in Bangladesh

Routine monitoring for subclinical infection is one of the key mastitis control approaches. However, the accuracy of the most commonly used screening tests has not yet been established. The aim of the present study was therefore to evaluate the accuracy of three screening tests, namely California mastitis test (CMT), white side test (WST), and surf field mastitis test (SFMT) for the screening of subclinical caprine mastitis. A cross-sectional study based on 484 randomly collected milk (242 goats) samples from three districts of Bangladesh was conducted for the screening of subclinical mastitis by the aforementioned tests. The Bayesian latent class model was implemented in WinBUGS to estimate the tests' characteristics and true prevalence of subclinical mastitis. The Bayesian posterior estimates of sensitivities with a 95% credible intervals (CrIs) were 98.60% (95.18-99.95%), 98.28% (94.56-99.92%), and 89.98% (83.39-95.03%), and specificities with 95% CrIs were 99.19% (98.11-99.96%), 99.27% (97.34-99.98%), and 99.28% (97.35-99.98%), respectively for CMT, WST, and SFMT. The true prevalence of subclinical caprine mastitis was estimated to be 43.49% (95% CrI 37.46-48.98%). The positive predictive values (PPV) of the three tests were similar. The serial and parallel interpretation of any test pairs increased the PPV and negative predictive value respectively close to 100%. Based on the simplicity, cost and performance as well WST and SFMT simultaneously could be recommended for the screening of caprine subclinical mastitis in Bangladesh.

Past, present, and future perspectives of small ruminant dairy research

The objectives of this paper are to review small ruminant dairy research in relation to the dimensions of the dairy goat and dairy sheep industries in the United States and the world. At least 10 countries depend on goats and sheep for between 30 to 76% of total milk supply. Leading among developed countries is Greece producing 178 kg milk per person per year with 61% from sheep and goats. Most developing countries need research, extension service, and public support to improve apparent productivity of goats and sheep. Domestic supply from all milk sources is <100 kg/person per year, and annual apparent yields average <100 kg of milk/goat, <50 kg of milk/sheep, which makes supplies of animal protein and calcium from domestic sources very low. Statistical data on goat and sheep production for United States are not available. The small population of DHIA tested US dairy goats averaged in recent years >700 kg of milk/goat per year, and some dairy sheep breeds may produce as much as 650 kg/yr. The need for more milk availability appears to be reflected in the dramatic increases of dairy goat populations during the last 20 yr: 52% for the world, 56% for developing, 17% for developed countries, while sheep populations decreased by 3% for the world, by 6% in developed, but increased 14% in developing countries. Research has been sparse on the unique qualities of goat and sheep milk compared with cow milk. Much development work by various agencies has been devoted to reducing mortality and improving feed supplies in harmony with the environment; this work is mostly published in proceedings of scientific meetings, often not in English. Results have shown in many cases that dairy goats and dairy sheep can be very profitable, even in developing countries with difficult climate and topographical conditions.

Milk N-acetyl-beta-D-glucosaminidase and serum albumin as indicators of subclinical mastitis in the camel

NAGase activity (NAGase) and serum albumin concentrations were determined in milk from 101 traditionally managed camels in the Sudan. NAGase, a lysosomal enzyme released from damaged epithelial cells as well as other somatic cells in milk, was recorded for quarter milk samples from camels (n = 353) using the fluoroscan method. NAGase activity in major pathogen-infected quarters was significantly (P < 0.05) higher than in minor pathogen-infected and non-infected quarters. Means for minor pathogen-infected quarters were also significantly higher than non-infected quarters. Concentrations of serum albumin, resulting from increased vascular permeability, in quarter milk samples (n = 320) were measured by the radial immunodiffusion test. Serum albumin content in milk was not affected by infection status of the quarter. There were, however, large variations in serum albumin levels and, to a lesser extent, NAGase values between samples in both infected and non-infected quarters. NAGase was more effective in predicting bacteriological status of the quarter than serum albumin.