Risk factors and prevalence of subclinical ketosis in dairy cows in Croatia

The purpose of this study was to assess the risks or associations between the prevalence of subclinical ketosis (SCK) and some periparturient diseases in Holstein cows, by determining beta-hydroxybutyrate (BHBA) serum levels using a Precision Xceed® BHBA meter (Abbott, USA) or spectrophotometer, and to evaluate the reproductive performance of cows positive for SCK. The study was conducted on 841 cows, from 107 randomly selected farms, aged 2-8 years, divided into two groups: positive (POS = BHBA level≥1200 μmol/L), with clinical or SCK, and a negative (control) group (NEG = BHBA level<1200 μmol/L). Blood samples were collected from lactating cows in the period between 1-15 days after parturition. There was a positive correlation (r = 0.99; P<0.0001) between BHBA determined spectrophotometrically and by using Precision meter. The correlation between BHBA concentration and milk yield (total lactation) was not significant (r = 0.04; P = 0.26). The POS group of cows had a significantly higher mean lactation yield (P<0.001) than the NEG group of cows (7076 kg vs. 6409 kg). The cows in the NEG group had a significantly shorter period of median days open to pregnancy (MDOP) compared to the POS group (124 vs. 138; P<0.0001). The hazard ratio (HR) for days open to pregnancy (DOP) in the POS group of cows was 0.66 (P<0.0001). The results showed that multiparous cows had 1.41 times more chance of being affected with SCK than primiparous cows. The prevalence of SCK was 15.8% in Holstein cows from central, northern, northwestern and eastern parts of Croatia. About 55.6% of the cows with SCK were affected by some of the observed periparturient diseases (relative risk was 1.91; P = 0.001).
Svrha ovog istraživanja bila je procijeniti rizike ili povezanost između prevalencije supkliničke ketoze (SKK) i nekih peripartalnih bolesti u krava holštajnske pasmine, određivanjem serumske razine beta-hidroksibutirata (BHBA) s pomoću elektroničkog uređaja Precision Xceed® BHBA device (Abbott, SAD) ili spektrofotometrijski te vrednovati reprodukcijska obilježja u krava pozitivnih na SKK. Istraživanje je provedeno na 841 kravi s nasumično odabranih 107 farmi, u dobi od 2 do 8 godina, podijeljenih u dvije skupine: pozitivne (POZ = BHBA razina ≥1200 μmol/L), s kliničkom ili SKK te negativnu (kontrolnu) skupinu (NEG = BHBA razina <1200 μmol/L). Uzorci krvi su prikupljani od krava u laktaciji tijekom razdoblja od 1. do 15. dana nakon teljenja. Ustanovljena je pozitivna korelacija (r = 0,99; P<0,0001) razine BHBA određene spektrofotometrijski ili pomoću elektroničkog uređaja Precision Xceed (Abbot, SAD). Korelacija između koncentracije BHBA i proizvodnje mlijeka (ukupne laktacije) nije bila značajna (r = 0,04; P = 0,26). POZ skupina krava imala je značajno višu prosječnu proizvodnju mlijeka (P<0,001) od NEG skupine krava (7076 kg vs. 6409 kg). Krave iz NEG skupine imale su značajno kraće razdoblje medijan dana do koncepije u usporedbi s POZ skupinom krava (124 vs. 138; P<0,0001). Omjer rizika za dane do koncepcije u krava iz POZ iznosio je 0,66 (P<0,0001). Rezultati ovog istraživanja su pokazali da su multiparne krave imale 1,41 puta veću vjerojatnost oboljeti od SKK nego primiparne krave. Prevalencija SKK u krava holštajnske pasmine u središnjim, sjevernim, sjeverozapadnim i istočnim dijelovima Hrvatske iznosila je 15,8%. Oko 55,6% krava sa SKK oboljelo je od nekih praćenih peripartalnih bolesti (relativni rizik je iznosio 1,91; P = 0,001)