The variability in the prevalence of subclinical and clinical mastitis and its impact on milk yield of Holstein and Simmental cows as a result of parity

This study analysed over 10 million test-day records collected between January 2005 and December 2022, to determine the prevalence of subclinical and clinical mastitis in Holstein and Simmental cows, and its impact on subsequent milk production. The daily somatic cell count (SCC) served as an indicator of subclinical (200,000/ml to 400,000/ml) and clinical (>400,000/ml) mastitis. The study found that mastitis-related problems increased with parity, and were more frequent in Holstein cows than in Simmental cows. The study identified factors affecting daily milk yield, including lactation stage, age at first calving, farm size, recording season, and breeding region. It was also found that subclinical and clinical mastitis significantly impacted milk production. The day when subclinical/clinical mastitis was detected (D-0) had the lowest milk yield, followed by an increase in milk production in the subsequent recordings. The increase in production varied depending on the form of mastitis, cow’s breed (Holstein or Simmental), and cow’s parity. The first successive milk recording (A-1) showed the greatest increase in daily milk yield across both breeds and all parities. The increase in daily milk yield was higher following clinical than subclinical mastitis, and was more pronounced in Holstein than in the Simmental breed. After the initial increase in milk production, almost all cows had a decline in milk yield in the subsequent period after subclinical mastitis. Further, a continued increase was observed in all cows after clinical mastitis. The analysis of monthly and total differences in milk production indicated that cows had the highest monthly increase in milk production in the first month after subclinical/clinical mastitis. The highest total increase in milk production was observed in Holstein primiparous cows, which amounted to 44.91 kg after clinical mastitis. In comparison to the Holstein breed, Simmental cows had a lower increase in milk production. Generally
U istraživanju je analizirano više od 10 milijuna zapisa na kontrolni dan, prikupljenih između siječnja 2005. i prosinca 2022. kako bi se utvrdila prevalencija subkliničkog i kliničkog mastitisa u krava holštajnske i simentalske pasmine te njegov utjecaj na kasniju proizvodnju mlijeka. Dnevni broj somatskih stanica (SCC) služio je kao pokazatelj subkliničkog (200 000/ml do 400 000/ml) i kliničkog (>400 000/ml) mastitisa. Utvrđeno je da se problemi povezani s mastitisom povećavaju s paritetom i da su češći u holštajnske nego u simentalske pasmine. Utvrđeno je da na dnevnu količinu mlijeka utječu različiti čimbenici, uključujući stadij laktacije, dob prvog teljenja, veličinu farme, sezonu, te regiju uzgoja. Također je utvrđeno da subklinički i klinički mastitis imaju značajan utjecaj na proizvodnju mlijeka. Na dan kada je otkriven subklinički/klinički mastitis (D-0) zabilježena je najniža mliječnost, dok pri sljedećim kontrolama mliječnosti slijedi povećanje proizvodnje mlijeka. Povećanje proizvodnje variralo je ovisno o obliku mastitisa, pasmini krava (holštajnska ili simentalska) i paritetu krava. Nadalje, pri prvoj sljedećoj kontroli mliječnosti (A-1) utvrđen je najveći porast dnevne količine mlijeka kod obje pasmine i u svim laktacijama. Porast dnevne mliječnosti bio je značajniji nakon kliničkog nego subkliničkog mastitisa te je bio izraženiji u holštajnske nego u simentalske pasmine. Nakon početnog povećanja proizvodnje mlijeka, kod gotovo svih krava došlo je do pada mliječnosti u narednom razdoblju nakon subkliničkog te kontinuiranog porasta nakon kliničkog mastitisa. Analiza mjesečnih i ukupnih razlika u proizvodnji mlijeka pokazuje da su krave imale najveći mjesečni porast proizvodnje mlijeka u prvom mjesecu nakon subkliničkog/kliničkog mastitisa. Najveće ukupno povećanje proizvodnje mlijeka zabilježeno je kod prvotelki holštajnske pasmine, koje je nakon kliničkog mastitisa iznosilo 44,91 kg. U usporedbi s holštajnskom pasminom, simentalske krave imale su man