Rumen Health Technical Guide

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Dimensions of Acidosis (Clinical & Subclinical)


Intensive farming practices require a high plane of nutrition, which typically includes high levels of fermentable carbohydrates which can put the animal at risk for developing metabolic disorders, in particular, challenges to rumen stability and sub acute acidosis.

Different degrees of acidosis appear when the fermentation profile of the rumen is unbalanced by high levels of lactic acid or butyric acid.26ReferenceView allKrause K.M., Oetze G. R. 2006.
Understanding and preventing subacute ruminal acidosis in dairy herds: A review. Anim. Feed Sci. Technol. 126 : 215-236.
27ReferenceView allEnemark J. M. D. 2008.
The monitoring, prevention and treatment of sub-acute ruminal acidosis (SARA): A review. The Vet. Journal 176 : 32-43.
28ReferenceView allGonzález L. A., Manteca X., Calsamiglia S., Schwartzkopf-Genswein K.S., Ferret A. 2012.
Ruminal acidosis in feedlot cattle: Interplay between feed ingredients, rumen function and feeding behavior (a review). Anim. Feed Sci. Technol. 172 : 66-79.
29ReferenceView allCastillo-Lopez E., Wiese B. I., Hendrick S., McKinnon J. J., McAllister T. A., Beauchemin K. A. and Penner G. B. 2014.
Incidence, prevalence, severity, and risk factors for ruminal acidosis in feedlot steers during backgrounding, diet transition, and fiishing. J. Anim. Sci. 92: 3053

Adapted from Nocek. 12ReferenceView allNocek J. E. 1997.
Bovine Acidosis: Implications on Laminitis. J Dairy Sci 80:1005-1028.

 

Sub Acute Ruminal Acidosis (SARA)

  • More common, results from excessive volatile fatty acid (VFA) production that exceeds the ability of the rumen to neutralize and it exceeds the absorption capacity of the ruminal papillae.
  • Rumen pH drops below 5.8 and remains bellow this threshold for three or more hours within a 24-hour period.
  • Animals generally have mild diarrhea, lowered dry matter intake and laminitis.
  • Can develop into acute acidosis if the pH is never able to recover.

Acute Ruminal Acidosis

  • Less common, more severe, usually occurs when pH falls below 5.5.
  • Usually associated to a drastic diet change.
  • Animals have depressed productivity, go of feed, have elevated heart-rate, diarrhea and may die.
  • Severe lactic acidosis may cause irregular feeding behavior and gorging, which creates more spikes of acid production.

 

Indicators and risk
parameters

General reasons
table-arrow-downANIMAL PERFORMANCE- Reduced average daily gain and increased feed conversion ratio may be due to impaired rumen fermentation in beef cattle.
- Low milk production, milk fat and a reduced fat/protein ratio may be due to impaired rumen fermentation in lactating dairy cattle.17ReferenceView allBritt J. S., Thomas R. C., Speer N. C., and Hall M. B. 2003.
Efficiency of Converting Nutrient Dry Matter to Milk in Holstein Herds. J. Dairy Sci. 86:3796–3801.
18ReferenceView allAllen M. S. 1997.
Relationship Between Fermentation Acid Production in the Rumen and the Requirement for Physically Effective Fiber. J. Dairy Sci. 80: 1447-1462
19ReferenceView allSauvant D. and Peyraud J. L. 2010.
FRENCH Calculs de ration et évaluation du risque d’acidose. INRA Prod. Anim. 23: 333-342.
table-arrow-downRUMINATING
ACTIVITY
A lack of ruminating activity may be due to reduced rumen motility during acidosis.18ReferenceView allAllen M. S. 1997.
Relationship Between Fermentation Acid Production in the Rumen and the Requirement for Physically Effective Fiber. J. Dairy Sci. 80: 1447-1462
30ReferenceView allGrant R. J., Colenbrander V.F. and Mertens D. R. 1990.
Milk Fat Depression in Dairy Cows: Role of Silage Particle Size. J. Dairy Sci. 73: 1834-1842.
table-arrow-downLOCOMOTIONLame animals can indicate high levels of rumen histamine production and bacteria endotoxin release.12ReferenceView allNocek J. E. 1997.
Bovine Acidosis: Implications on Laminitis. J Dairy Sci 80:1005-1028.
table-arrow-downRUMEN FILL
An empty rumen can indicate poor rumen efficiency because of irregular intake.22ReferenceView allZaaijer D. and Noordhuizen J. P. T. M. 2003.
A novel scoring system for monitoring the relationship between nutritional effiency and fertility in dairy cows. Irish Vet. Journal 56 : 145-151.
table-arrow-downMANURE CONSISTENCY
Liquid feces can indicate poor rumen effiency due to an increased passage rate, from an imbalanced diet and more lower gut fermentation.20ReferenceView allHall M. B. 2002.
Characteristics of manure: what do they mean? Proceedings of the Tri-State Nutrition Conference. Pages 141-147. April 16-17, 2002
21ReferenceView allHutjens M. F. 2010
University of Illinois. Manureology 101.
22ReferenceView allZaaijer D. and Noordhuizen J. P. T. M. 2003.
A novel scoring system for monitoring the relationship between nutritional effiency and fertility in dairy cows. Irish Vet. Journal 56 : 145-151.
table-arrow-downCLEANLINESSAn increased passage rate from an imbalanced diet and low digestibility can lead to unclean animals.
table-arrow-upUNDIGESTED GRAINUndigested processed grains in the feces because of poor rumen efficiency may be due to an increased passage rate due to an imbalanced or low diet digestibility. 20ReferenceView allHall M. B. 2002.
Characteristics of manure: what do they mean? Proceedings of the Tri-State Nutrition Conference. Pages 141-147. April 16-17, 2002
table-arrow-upHEAT STRESSHeat stress increases the risk of acidosis and low fiber degradation as:
> Eating behavior is modified: cows prefer to eat in “blocks” in the cooler times of the morning and later evening.
> Dry matter intake is decreased with lower proportion of forage and higher levels of fermentable carbohydrates.
> High loss of saliva (from drooling and open-mouthed breathing) in hot weather decreases the amount of natural buffers to the rumen.31ReferenceView allBurgos Zimbelman Rosemarie and Collier Robert J. 2011.
Feeding Strategies for High-Producing Dairy Cows During Periods of Elevated Heat and Humidity. Tri-State Dairy Nutrition Conference pages 111-126.
rumen-wall-healthy-photo-lallemand-forward
Healthy rumen papillae
rumen-wall-damaged-photo-lallemand-forward
Rumen wall damaged by acidosis

Financial impacts

The financial impact of rumen acidosis is staggering.

In lactating dairy cows, economic loss can be attributed to: lower milk fat content (-0.76%), depressed milk production (-10%), poor reproductive performance and increased risk of secondary metabolic disorders. One study estimates the overall impact to the U.S. dairy industry is between $500 million and $1 billion per year.32ReferenceView allKrause K.M., Oetzel G.R. 2006.
Understanding and preventing subacute ruminal acidosis in dairy herds : A review. Anim. Feed Sci.Technol. 126 : 215-236. (includes citations from Donovan 1997 and Stone 1999).

Another study estimates sub acute acidosis costs $34,750 per 100 cows.33ReferenceView allZebelli Q. et Ametaj B. N. 2009.
Relationships between rumen lipopolysaccharide and mediators of inflammatory response with milk fat production and efficiency in dairy cows. J. Dairy Sci. 92 :3800–3809.

In growing and finishing beef cattle,  economic loss can be attributed to: lower growth rate (-78g/hd/d; -0.17 lbs/hd/d),  impaired feed-to-gain conversion, lower meat grades, and increased risk of secondary metabolic health events.34ReferenceView allThompson P. N., Hentzen A., Schultheiss W. A. 2006.
The effect of rumen lesions caused by subclinical acidosis on growth in feedlot calves. Proceedings of the XIth International Symposium for Veterinary Epidemiology and Economics, Cairns, Australia, 6-11 August 2006.