Metabolic disorders in dairy Simmentals - prevalence risk and effect on subsequent daily milk traits

In order to analyse metabolic disorders in Simmental cows, 2.641.223 test-day records have been used. The metabolic disorders prevalence risk was indicated by the fat to protein (F/P) ratio, while the subclinical disorder was demonstrated using the F/P ratio and daily production. In terms of the ketosis prevalence risk (KPR), the highest prevalence risks occurred at the 20th lactation day in all tested cows with exception of cows in parity P4+ which experienced peak prevalence risk at 25th lactation day. A steady decrease of KPR after peak prevalence was observed in all animals except the 3rd lactation cows which experienced the second peak prevalence at the 30th lactation day, after which the prevalence risk continued to decline. The highest acidosis prevalence risk (APR) was detected among 4+ parity cows. Considering the lactation stage, the highest APR occurred within the first 10 days, with the indication from 16 to 23 %, depending on parity. The peak prevalence risk was followed by a considerable decline during the ensuing 20 days. The prevalence risk began to increase among all cows after the 25th lactation day. Furthermore, there was a considerable decrease in a daily milk yield and variation of daily milk contents due to subclinical disorders. The most noticeable drop in daily milk yield, for both ketosis/acidosis, was detected in cows in 4+ parity in the amounts of 7.45 kg/day and 2.73 kg/day respectively. There was also a production decline in the subsequent milk controls. Subclinical disorders can also substantially change daily milk contents. The daily fat content was considerably reduced by the subclinical ketosis and the same parameter was considerably increased by the subclinical acidosis. The opposite trends were detected for daily protein content. Since indication criteria was set on Holstein population and considering the fact that Simmental cows produce noticeably less, some adjustment is needed before a routine use of test-day records for early detection of metabolic disorders in dairy Simmental herds.