measurement of milk urea level, its role in diagnosis, practical applications. Herd and individual diagnosis based on milk and urinary ketone bodies in dairy cattle, ketonuric index:

Question 1

Physio of food/aa’s in the rumen

Answer 1

The CP in feed is broken down into NPN and true protein
The NPN is broken down to NH3 in the rumen
The RDP is broken down to amino acids in the rumen. The aa’s and NH3 are used to form microbial protein (along with FOM) and this with the UDP forms aa’s that are delivered to tissues

Question 2

The milk urea level

Answer 2

Indicates the protein: E in the ration
if less than normal- then bad for milk production
if more than normal- then bad for repro!
When its higher, is usually caused by high RDP or low E

Question 3

What is the optimal milk urea level and why does it change?

Answer 3

3.5-6 mmoll
Different phases of lactation
Max 2-4 hrs after feeding
Xs RDP or low RFC

Question 4

Overfeeding of RDP- 6 points to mention

Answer 4

In rumen- ammonia
In liver- urea
Metab: incr BG, NEFA’s, E demand, MUN, PUN
Toixc: sperm, ovum, embryo
Endocrine: decr insulin, GnRH–decr LH and FSH, decr P4 from CL
NB to keep stable in the first lactation phase i.e 100 days post partum, because will alter pH of uterus and vagina- decreasing the conception rate and therefore decr fertility

Question 5

Implications of high UDP and its max amount in the ration

Answer 5

if incr UDP at peak milk production– impaired fertility because the first estrus occurred later
Cows forced to mobilize body reservoirs- because if RDP is low- microbial prolif is inhibited and decr bact E production
UDP max is 40% of total dietary!!

Question 6

What are foods high in UDP

Answer 6

Corn gluten
Dried distillers grains with solubles
Heat treated soya
Hot pressed rapeseed cake

Question 7

What is the protein balance

Answer 7

MPN-MPE and should be +100-150

Question 8

What are the milk and urinary ketone bodies levels??

Answer 8

Should conduct individual measurements to gain E statuses of entire herd!!
BHB<1mmol/l
Acetoacetic acid <0.4 mmol/l
Acetone < 0.7 mmol/l

Question 9

What is the Ketonuric Index and how is it measured

Answer 9

KB level and interval from calving 
Use Rotheratest (ketostix) which is Nitroprusside Na- purple ring appears when KB's are present (not for BHB though
No KB when 0-4 even 5 +

Question 10

Determination of Kentonuric index

Answer 10

10x the number of + and 2x the number of days before calving
Before calving is + because ketosis is more critical
After calving is -
(look at worked example)

Question 11

Evaluation of Ketonuric index

Answer 11

> 20-25 the group is in NEB so improvement of E status is needed
40g/dl: life threatening

Question 12

What happens when you decr E and incr NH3 of the ration

Answer 12

N is wasted in urine and milk

Question 13

What happens when you incr E and decr NH3 of the ration?

Answer 13

Lactate is produced because the E is not used for protein synth

Question 14

What causes the milk urea to be greater than optimal?

Answer 14

Excess RDP

Low RFC

Question 15

Factors influencing the milk urea conc

Answer 15

Cow: state of nutrition, breed, maturity, health, BW
Environment: summer>winter, housing
Sample collection: afternoon>morning, skim-milk>whole-milk

Question 16

Primary ketosis (type 1)

Answer 16

Starvation— E def— decr milk prod

Question 17

Secondary ketosis (type 2)

Answer 17

Other diseases causing decr appetite in early lactation e.g displaced abomasum, mastitis, metritis