Influence of udder infection status on milk enzyme activities and somatic cell count throughout early lactation in goats

At present the analysis of somatic cell count (SCC) used for the detection of intramammary infections (IMI) in bovine milk is also recommended for goat milk, but due to the various factors influencing SCC it allows only limited conclusions on the udder health of goats. The research on enzyme activity in milk appears to show promise in finding an approach with more suitable indicators of the early detection of IMI in goats. Therefore, the present study aimed to investigate the influence of goat udder infection status on different milk enzyme activities and SCC throughout early lactation. A total of 60 dairy goats were sampled at weekly intervals over a period of 6 weeks after kidding and the bacteriological status, milk SCC and the activity of N-acetyl-β-d-glucosaminidase (NAGase), β-glucuronidase and lactate dehydrogenase (LDH) of udder halves were analysed. Infections with minor or major pathogens were identified in 47% of all animals over the sampling period. Coagulase-negative staphylococci (CNS) represented the main group of pathogens in bacteria isolates (16.4%). Corynebacteria and major pathogens were detected in 7.2% and 5.7% of udder half samples. Excluding the first week after parturition, the study revealed a highly significant influence of lactation week on log10 SCC (F4,255=11.63, p<0.001) and log10 LDH (F4,285=5.02, p<0.01) and must be acknowledged as the most dominating predictor on NAGase activity (F4,250=29.62, p<0.001) in early lactation. Levels in β-glucuronidase activity were not influenced by the stage of lactation. The infection status of udder halves had a highly significant effect on log10 SCC (F3,528=18.88, p<0.001), log10 β-glucuronidase (F3,407=11.02, p<0.001) and log10 LDH (F3,534=12.39, p<0.001). We revealed no effect of different pathogenic groups on NAGase activity, thus this parameter proved not to be suitable as an indicator for udder infections in early lactation. The proposed milk enzymes β-glucuronidase and LDH might be indicative of inflammatory processes, but the influence of parity and lactation stage on the overall results should be considered in the assessment of udder health in dairy goats.