Subacute ruminal acidosis in dairy cows - physiological background, risk factors and diagnostic methods / Levente Kovács, László Rózsa, Mátyás Hejel, Walter Baumgartner, Otto Szenci.
Sažetak

According to the latest studies, the prevalence of subacute ruminal acidosis (SARA) is around 20% in early and mid- lactation dairy cows, generating annual losses in the United States of approximately USD 500 million to 1 billion. The diagnosis of SARA is still difficult due to lack of pathognomonic clues and the delayed appearance of certain clinical signs. Therefore, SARA remains neglected or even unrecognized in many dairy herds. SARA is characterized by daily episodes of low ruminal pH, when the pH remains in the range of 5.2 to 6 for a prolonged period due to the accumulation of short-chain fatty acids and insufficient rumen buffering. The causes of SARA are related to high-grain diets, such as feeding excessive amounts of non-structural carbohydrates and highly fermentable forages, and insufficient dietary coarse fibre. SARA is associated with the inflammation of several organs and tissues in dairy cows, and its main long-term health and economic consequences are the fluctuation of feed intake, reduced fibre digestion, depression of milk yield and milk fat content, gastrointestinal damage, diarrhoea, laminitis, liver abscesses, and lameness. The aim of this review is to summarize the information available on the physiological aspects, risk factors, prevalence and possible indicators of SARA in dairy cattle. Basedon the existing literature, rumenocentesis and the use of an oral stomach tube are reliable field techniques to detect SARA. Nowadays, improved field techniques allowing the continuous measurement of reticuloruminal pH are also available for better diagnosis of SARA. Wireless indwelling pH probes may become important tools for the continuous measurement of ruminal pH in the coming years.; Prema najnovijim istraživanjima, pojavnost subakutne acidoze buraga (SARA) je oko 20 % u mliječnih krava u ranoj i srednjoj laktaciji, a prouzroči gubitke od približno 500 milijuna do 1 milijarde američkih dolara godišnje u SAD. Dijagnostika SARA je još uvijek problematična zbog nedostatka patognomoničnih karakteristika te kašnjenja pojavnosti određenih kliničkih znakova. Stoga je SARA i dalje zanemarena pa čak i neprepoznata u mnogim stadima mliječnih krava. SARA karakteriziraju dnevne epizode niskog pH buraga, kada se pH vrijednost kreće u rasponu od 5,2 do 6,0 kroz duže vrijeme, zbog nakupljanja nižih masnih kiselina i nedovoljnog puferiranja sadržaja buraga. Uzroci SARA povezani su s obrocima bogatim koncentratima, kao što je pretjerano davanje nestrukturnih ugljikohidrata i visoko probavljive voluminozne krme s nedovoljno grube voluminoze. SARA je povezana i s upalom različitih tkiva i organa u mliječnih krava, a njezine dugotrajne posljedice uključuju promjenjiv unos hrane, smanjenu probavu vlakana, smanjenu proizvodnju mlijeka i mliječne masti, oštećenja probavnog sustava, proljeva, laminitis, apscesi na jetri i šepavost. Cilj ovog preglednog rada je sažeti trenutno dostupne podatke o fiziološkim aspektima, činiteljima rizika, pojavnosti i potencijalnim indikatorima SARA u mliječnih krava. Prema trenutnoj literaturi jedine terenske metode za dijagnostiku SARA uključuju ruminocentezu i korištenje sonde buraga. Danas postoje poboljšane terenske dijagnostičke metode za kontinuirano mjerenje retikoruminalnog pH i lakšu dijagnostiku SARA. Bežične sonde koje kontinuirano mjere pH sadržaja buraga trebale bi postati sve značajnija dijagnostička metoda u skorijoj budućnosti.