Sub acute ruminal acidosis (SARA) Flashcards
1
Q
What is the speed of metabolism of different carbohydrates What does fermentation of carbohydrates form?
A
- Fibre = slow
- Starches = medium
- Sugars = fast
- Fermentation of carbohydrates = Volatile Fatty Acids
2
Q
How does rumen acidosis occur?
A
- 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
3
Q
What should rumen pH be?
What happens if pH decreases?
A
- 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
4
Q
What factors affect rumen pH?
A
- 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
5
Q
What is important about cow saliva?
A
- Produced when chewing long fibre
- Cudding
- Contains sodium bicarbonate
- Healthy cow = 3.5kg/day of saliva
6
Q
What are benefits of long fibre?
A
- Encourages cudding - bicarbonate buffers acid
- Forms a rumen mat - keep food particles in rumen to be digested + home to biofilms
7
Q
What are risk factors for SARA?
A
- 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
8
Q
What are signs of SARA?
A
- pH <5.5
- Most common nutritional disorder
- Loose + soft faeces
- Swishing tails - sore bums
- ‘dirty’ cows
- Undigested grains + long fibre present
9
Q
What are effects of SARA?
A
- Reduced DMI
- Reduced digestibility = reduced energy intake + NEB
- Immunosuppression = disease susceptibility
10
Q
What are production effects of SARA?
A
- Poor yields = poor peak yields + decline in yield
- Milk quality = low butterfat + variable milk protein
- $1.20/day/coq
11
Q
What can SARA predispose?
A
- 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
12
Q
How can you diagnose SARA?
A
- 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
13
Q
When should you take ruminal pH samples?
A
- 2-4hrs after feeding - pH should be 6.0-7.0
- Sample 6 cows
pH <5.7 = SARA
14
Q
What are your options for rumen sampling?
A
- Rumenocentesis = LHS level of stiffle, clip + scrub, LA, insert 3-5” needle 16G-18G
- Oral sampling devices (care w saliva contamination)
15
Q
When does Acute ruminal acidosis occur?
A
- Overeating grain - barley poisoning
- Sudden introduction of high levels of grain - barley beef
