L14: Ketosis Of Dairy Cows (Risco) Flashcards
3 ketone bodies
BHBA
Acetoacetate
Acetone
Energy balance =
(NE dmi - NE m - NE I) + NE bwt
Peak milk yield occurs when
4 weeks PP
Peak DMI occurs when?
8 weeks PP, and is about 3.5% of BW
Why does cow go into negative energy balance PP?
Milk yield peaks before DMI peaks, so fat is mobilized to make up deficit
Propionate is converted to what via the TCA cycle?
Oxaloacetate, then glucose
Ketone body precursors
NEFAs from adipose tissue stores –> FFA –> acetate –> Acetyl CoA –> acetoacetyl CoA –> acetoacetate –> acetone and BHBA
-acetyl CoA should normally go into TCA cycle to make glucose, but if oxaloacetate is low, it instead goes to form ketone bodies**
Ketosis occurs when:
- absorption/production of ketone bodies is greater than their use for energy source
- NEFAs are high
- ketone bodies are high
- blood glucose is low
Most common ketone body used to diagnose SUBCLINICAL ketosis and concentration cutoffs***
BHBA
Lower threshold concentration of BHBA for SCK is 1.2 mmol/L, so SCK = 1.2-2.8 mmol/L***
Clinical signs develop when >3.0 mmol/L***
Sequelae of SCK
- inappetance w/ wt. loss
- reduced fertility and milk production
- increased risk for LDA and herd removal
- immunosuppression (predisposing to metritis and mastitis)
Clinical ketosis manifests as:
Acute onset of bizarre neuro signs: -excessive grooming, licking -head-pressing, ataxia, wandering, leaning -apparent blindness -hyperesthesia, bellowing, aggression BHBA > 3.0 mmol/L
Clinical/nervous ketosis Ddx
Hypermagnesemia
Rabies
Acute lead poisoning
Listeriosis
Median time for resolution of SCK
5 days
Average SCK incidence rate (in NY)
43%
Incidence of SCK =
(# new cases of SCK during the risk period)/(# cows that completed the risk period)
- must measure BHBA conc. Twice
- approximately 2.2 x the prevalence
- better than prevalence at estimating the impact of SCK in a dairy herd*
Prevalence of SCK =
The proportion of cows with BHBA concentration between 1.2-2.9 mmol/L at a given point in time (7-14 days PP)
- doesn’t require repeat measurements
- not as good as incidence at estimating impact over time
Risk factors for ketosis
- age: older cows
- BCS 4 or higher
- BCS loss of >1 during first 60 DIM**
- lower DMI due to dz, temp change, inadequate housing, dietary factors
Clin path of ketosis
- BHBA >1.2 mmol/L
- hypoglycemia (20-40 mg/dl)
- liver enzymes may be elevated w/ lipidosis
- mild electrolyte abn. If off feed
- stress leukogram
- increased NEFAs
Dx of ketosis
- hepatic lipidosis at necropsy
- elevated ketone bodies in plasma, urine, and/or milk
Which ketone bodies detected in urine?***
Acetoacetate
Acetone
Most common ketone body found in urine
Acetoacetate
Which ketone body can be detected in milk?***
BHBA
Which ketone bodies detected in blood?***
BHBA
Acetone
Acetoacetate
Which ketone body used to determine if ketosis is clinical?***
BHBA
Precision Xtra blood test has highest sensitivity and specificity in detecting subclinical ketosis (better than Ketolac and Ketostix)
:)
Treatment goals for ketosis
- restore normal DMI to resolve hypoglycemia, hyperketonemia and break the cycle that leads to excess ketogenesis
- ID and tx underlying conditions
Glucose precursors
IV dextrose (an isomer of glucose) -causes a transient increase in glucose (most lost in urine) Propylene glycol Propionate Glucocorticoids Insulin
Oral propylene glycol as tx for hypoglycemia
- use 8-14 oz. drench SID-BID 3-5 days
- rumen motility required for absorption
- metabolized in liver to glucose
- toxicity can –> appetite suppression, diarrhea
Glucocorticoids as tx for hypoglycemia
- shifts glucose distribution and utilization by increasing blood glucose and decreasing milk production by less uptake
- stims. Appetite
- don’t use in pregnant cows or cows w/ concurrent infectious dz
- may not be good to use if hepatic lipidosis present (controversial) - may increase lipolysis and NEFAs
- dexamethasone or isoflupredone acetate used
- must administer dextrose in conjunction
Caution with isoflupredone acetate for ketosis tx
May increase hypokalemia due to mineralocorticoid activity
-if used, only use once
Rank txs for ketosis
Best: propylene glycol
Ok: dextrose
Worst: steroids
Prevention of ketosis
- maximize DMI in transition cows
- avoid over-conditioning late lactation cows
- niacin fed in transition rations to decrease blood ketone lvls
- propylene glycol administered prophylactically to high-risk animals
- monensin increases production of propionate in the rumen (can decrease SCK in early lactation by 50% if given during late dry period)
- monitor incidence of SCK 3-16 days PP
- adequate bunk space
Ketosis
Abnormally elevated concentrations of circulating ketone bodies
- can be clinical or subclinical (most subclinical**)
- during early lactation most common
