Lecture 23: Dairy Clinical Nutrition Case

problem list for cow herd evaluation

• behavior: lethargy, reduced rumination, decreased lying

• GI: decreased rumen motility, decreased rumen fill, mild diarrhea

• production: variable and decreased milk production, possible decreased DMI

what is the most serious issue from the herd evaluation?

decrease in rate of rumen contractions

why might rumen contractions be decreased?

decreased pH → causes rumen motility to decrease

what should be done after creating the problem list?

bloodwork, increase rumen pH, ruminocentesis

what diagnostic test would you prioritize for these cows?

rumen pH

is an orogastric tube a good choice for checking rumen pH?

no

why is an orogastric tube not good for checking rumen pH?

• collecting fluid close to cardia region → likely to be more buffered

• need a large volume to be accurate with this method

when should a ruminocentesis be performed relative to feeding?

• wait at least 6 hours after feeding

• window is 6-12 hours after feeding

• need at least 1ml, use pH meter

what is a normal fluctuation in rumen pH over 24 hours?

0.5-1 pH units

fecal and urine pH results

• fecal: 6.1 (normal is 7.0)

• urine: 7.7 (normal is 8.5)

• poor correlation with rumen pH due to hindgut buffering

milk fat results

• average milk fat: 3.2% (normal is 3.7%)

• may decrease with low rumen pH due to lower acetate production in the rumen as lactate production increases

• insensitive indicator of SARA

ruminocentesis results

• 6/10 cows: rumen pH = 5.3

• measured 8 hours post-feeding

• rumen pH should recover to >5.8 post-feeding

• 25% of cows with pH <5.5 = diagnostic for SARA

characteristics for SARA diagnosis

• periodic low rumen pH

• reduced feed intake

• decreased milk production and milk fat

• mild diarrhea

• herd-level issue

• increased levels of VFAs (some lactic acid) → prolonged decreased pH → associated with lack of fiber

what questions related to diet will you ask the dairy manager?

peNDF content, frequency of feedings

proper transition of diet

3-4 weeks

formulated diet

• corn silage and hominy → 59% of diet (no more than 60% of grain)

• corn silage = 50% grain, 50% forage → low fermentable carbs

which fiber fraction is most important for rumen health?

peNDF

recommended peNDF

>22%

feeding management findings

• inconsistent ingredient weights → too much silage/hominy, too little haylage

• inadequate mixing time

• new employee started 2 weeks ago

• result → reduced effective fiber, increased risk of acidosis

primary treatment for SARA

• correct diet formulation and mixing

• increase peNDF

prevention/management for SARA

• ensure accurate weighing of ingredients

• train personnel thoroughly

• maintain consistent mixing time

• deliver and push up feed consistently