Sub acute ruminal acidosis (SARA)

Question 1

What is the speed of metabolism of different carbohydrates What does fermentation of carbohydrates form?

Answer 1

• Fibre = slow
• Starches = medium
• Sugars = fast
• Fermentation of carbohydrates = Volatile Fatty Acids

Question 2

How does rumen acidosis occur?

Answer 2

• Rapid carbohydrate digestion = rumen pH decreases
• Reduced saliva flow = rumen pH decreases
• Decreased rumen pH = decreased carb digestion = decreased microbial activity = D lactic acid produced
• Decreased rumen pH = energy yield from digestion decreases = lactic acid producing microbes increase = Lactic acid produced

Question 3

What should rumen pH be?
What happens if pH decreases?

Answer 3

• pH = 6-7
• low pH kills bug population = growth of lactobacilli = lactic acid cannot be metabolised
• Digestion fails = osmotic diarrhoea, colonic acidosis
• Low pH = destroys papillae = rumenitis

Question 4

What factors affect rumen pH?

Answer 4

• How much VFA’s produced
• Type of acid produced - lactic acid = strong
• Rate of fermentation - fibre (slow), concentrates (fast)
• Rate of acid removal = absorption across rumen wall
• Buffering by saliva - chewing cud

Question 5

What is important about cow saliva?

Answer 5

• Produced when chewing long fibre
• Cudding
• Contains sodium bicarbonate
• Healthy cow = 3.5kg/day of saliva

Question 6

What are benefits of long fibre?

Answer 6

• Encourages cudding - bicarbonate buffers acid
• Forms a rumen mat - keep food particles in rumen to be digested + home to biofilms

Question 7

What are risk factors for SARA?

Answer 7

• Insufficient long fibre in the diet * for TMR 2.5-10cm
• Inaccurate fodder DM estimation – insufficient fodder provided
• Overmixing of TMR
• Excessive feeding of sugars and starches
• Poor dry cow management
• Slug feeding of concentrates in the parlour
• Food deprivation and irregular feeding
• Poor cow comfort

Question 8

What are signs of SARA?

Answer 8

• pH <5.5
• Most common nutritional disorder
• Loose + soft faeces
• Swishing tails - sore bums
• ‘dirty’ cows
• Undigested grains + long fibre present

Question 9

What are effects of SARA?

Answer 9

• Reduced DMI
• Reduced digestibility = reduced energy intake + NEB
• Immunosuppression = disease susceptibility

Question 10

What are production effects of SARA?

Answer 10

• Poor yields = poor peak yields + decline in yield
• Milk quality = low butterfat + variable milk protein
• $1.20/day/coq

Question 11

What can SARA predispose?

Answer 11

• Displaced abomasum - VFA’s enter abomasum = atony
• Digestive upsets
• Ketosis (NEB)
• Lameness - sub-clinical laminitis = ulcers, white line
• Mastitis - dirty cows
• Poor resistance + health
• Infections - endocarditis
• Poor fertility = cows not seen bulling + poor conception

Question 12

How can you diagnose SARA?

Answer 12

• Clues =
  -Fertility
  -Lameness
  -Ketosis
  -LDA
  -Faeces
  -“odd sick cows”
• Observe the group.
  -cudding.
  -rumen fill.
  -tail swishing.
  -cleanliness score.
• Condition Score = dry – peak > 0.5 loss in CS
• Faeces = score 1-5, sieve faeces.
• History = nutritional management.
• Definitive Diagnosis = Measure rumen pH

Question 13

When should you take ruminal pH samples?

Answer 13

• 2-4hrs after feeding - pH should be 6.0-7.0
• Sample 6 cows
  pH <5.7 = SARA

Question 14

What are your options for rumen sampling?

Answer 14

• Rumenocentesis = LHS level of stiffle, clip + scrub, LA, insert 3-5” needle 16G-18G
• Oral sampling devices (care w saliva contamination)

Question 15

When does Acute ruminal acidosis occur?

Answer 15

• Overeating grain - barley poisoning
• Sudden introduction of high levels of grain - barley beef

Question 16

What is acute ruminal acidosis?

Answer 16

pH <5.0

Question 17

What are clinical signs of acute ruminal acidosis?

Answer 17

• Distended rumen = bloat
• Ataxia
• Diarrhoea - profuse + smelly
• Depression
• Recumbency + shock

Question 18

How would you triage acute ruminal acidosis animals?

Answer 18

• Mild – almost normal
• Sub-acute – fairly bright, eats, no ataxia
• Acute – ataxia, anorexia, dilated pupils
• Peracute – severe ataxia or recumbency, apparently blind, severe dehydration

Question 19

How would you treat different acute ruminal acidosis?

Answer 19

• Mild = give hay to eat + observe
• Subacute = oral antacids = magnesium hydroxide / carbonate + feed hay
• Peracute = rumenotomy = empty rumen content, 5L 5% sodium bicarbonate + fluids for 12-24hrs

Question 20

How can you prevent acidosis?

Answer 20

• Good fibre source
• Correct mixing of diets
• Care with introduction of grain to fattening animals