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Prevention of Sub-Acute Rumen Acidosis (SARA) in DairyCows 

R. D. Shaver, Ph.D.
Department of Dairy Science
University of Wisconsin– Madison 

It has been suggested that sub-acute rumen acidosis (SARA)is the most important nutritional disease of dairy cattle (Oetzel, 1997).Laminitis is most commonly caused by SARA or an interaction between SARA andexcess standing time on concrete (Nordlund, 1995). Diagnosis of SARA problemherds is often difficult, partially because depressed bulk tank milk fat percentageis not a consistent observation for these herds (Oetzel, 1997).

Useful parameters to evaluate in the diagnosis SARA problem herds include:

Diet neutral detergent fiber (NDF), effective NDF, and nonfiber carbohydrate (NFC)     
Forage, grain, and total mixed ration (TMR) physical form
Feed bunk management 
Chewing activity 
Body condition 
Incidence of laminitis 
Incidence of transition cow metabolic and other digestive disorders 
Herd or group dry matter intake (DMI) and incidence of off-feed problems
Bulk tank milk fat test and incidence of milk fat/protein test inversions 
Rumen pH via rumenocentesis (Nordlund, 1995; Oetzel, 1997).

Because diagnosis of SARA problem herds before economic loss has occurred is difficult, prevention of SARA is the best approach.Recommended feeding guidelines and practices for prevention of SARA are as follows: 

Meet or exceed dietary fiber minimums of 18-21% acid detergent fiber (DM basis) and 27-30% NDF (DM basis) 
Meet or exceed dietary NDF from forage minimums of 18-21% (DM basis) for haycrop silage based diets and 21-23% (DM basis) for corn silage based diets 
Do not exceed 35-40% NFC (DM basis) 
Provide TMR with 8-10% of as-fed particles on the top screen of Penn State/Nasco shaker box 
Evaluate and regulate rate of ruminal starch fermentability by manipulating grain moisture content and fineness of grind 
Monitor and prevent over-mixing or over-processing of the TMR 
Monitor and minimize separation during feed mixing and delivery 
Monitor and minimize sorting in the feed bunk 
Periodically calibrate TMR scales 
Monitor and control daily variation in amounts of individual feed ingredients added to the TMR 
Routinely check moisture content of wet feeds and adjust rations accordingly to ensure correct DM ratio of forage to concentrate 
Limit corn silage as a percent of forage DM to 75% or less for lactating cow diets and 50% or less for dry cow diets 
Feed close-up dry cows 35-40% NFC diets (DM basis) to adapt the rumen microbial population and develop the rumen papillae prior introducing the high-group diet 
Do not feed less than 50% forage (DM basis) in the close-up dry cow diet; this diet may benefit from addition of baled hay 
Feed a post-fresh transition diet that contains more total NDF and NDF from forage than the high-group diet; this diet may benefit from addition of baled hay 
Feed buffers
In component feeding situations, increase grain feeding to peak amounts gradually over the first six weeks of lactation and feed grain 3 to 4 times daily 
In component feeding or partial TMR situations, monitor and control selective consumption of grain vs. forage or corn silage vs. haycrop silage 
Minimize effects of heat stress on selective consumption of grain vs. forage.

 

References
Nordlund, K. 1995. Questions and answers regarding rumenocentesis and the diagnosis of herd-based subacute rumen acidosis. Proc. 4-State Applied Nutrition and Management Conference. 
La Crosse, WI Oetzel, G. 1997. Using rumenocentesis to diagnose subacute ruminal acidosis in dairy herds. Proc. 4-State Applied Nutrition and Management Conference. La Crosse, WI 