Metabolic profile tests are based on the concept
that laboratory measurement of certain components of the blood will reflect the
nutritional status of animal with or without the clinical abnormality, For
example- Lower than normal mean blood glucose in a group of cows may indicate
an insufficient intake of energy which may or may not be detectable clinically.
The need of metabolic profile tests is because they
somehow helps in Predicting the existence of metabolic diseases in advance and
indicates towards the adoption of control strategies in order to prevent any
economical loss in future.
Challenges that comes in way for doing
metabolic profile tests.
This includes dealing with extraneous sources of
variation and it requires sampling strategies ( based on animal grouping and
testing of multiple animals).Larger herds-more suitable because of better
design sampling strategies as the spread of cost of testing among large no of
animals. Apart from these challenges, an availability of Regional diagnostic
laboratory with full tools and equipments is required to run various tests and
to interpret them.
Metabolic profiles for individual cows-
there are no well established protocols for tests to
be done in individual cows as tests conducted on an individual cows
using many serum enzymes and electrolytes as indicators have not proved to be
useful if used on one occasion.
This tests is important under management conditions
Heavy concentrate feeding
These tests are used for
prevention of periparturient diseases in dairy cows. In herds with high incidences
of periparturient diseases, low blood values of haematocrit ,albumin ,glucose, cholesterol , calcium and magnesium
were observed in dry period. The values correctively diagnosed mal nutrition as
the cause of periparturient diseases.
and statistical basis for herd testing
The interpretation of herd based test for metabolic diseases is different from interpretating
laboratory tests from individual
cows.Tests from individual cows are interpreted by comparing value to a normal
reference range.Normal ranges are often derived by calculating a 95%
confidence interval of tests results from 100 or more clinically normal
animals.The minimum sample size for
herd based tests is 12 cows.The
collection and use of background information of the farm, feeding and
feeding system and physical state and performance of the cows.
Variables in dairy herd metabolic
Energy balance: NEFAs i.e non estrified fatty acids are the sensitive
indicators of energy balance which is useful in monitoring energy status of
cows in last one month of gestation period where high values indicate negative
energy balance which further indicates some illness or metabolic disorder.
Case study :- in a case
study it was seen that between day 0
and 6 day after calving , cows with NEFA concentration of > 0.5 mEq/L WERE
3.6 times more likely to develop LDA after calving. In another study, cows with
plasma NEFA >0.3mEq/L between 3 and 35 days before calving were twice as
likely to develop LDA.
Serum B-hydroxybutyric acid (BHBA):-
Serum BHBA concentrations
are affected by energy and glucose balance. this test is less specific
indicator of energy balance than plasma NEFA. High values
indicates-reduced milk production, increased clinical ketosis, LDA and reduced
fertility.Sub clinical ketosis may starts up at serum concentration above
100?mol/L.THIS blood BHBA is gold standard test for sub clinical ketosis.
concentration generally lowers in early lactation and winters and there are several
factors may cause short term decrease in blood glucose.It decreases at the time
of milk secretion and is affected by chemical nature of carbohydrate, physical
form of the feed and roughage content of the feed. Elevation of blood glucose
level is also associated with excitement and low environmental temperature.
Protein nutrition & metabolism:-
Urea nitrogen testing to
evaluate the protein. Milk urea nitrogen MUN used as management aid improve and
monitor the nutritional status of lactating dairy cows.Elevated MUN indicates
excess protein has been fed to dairy cow for her given level of production and
any Increase in plasma urea & ammonia says inefficient nitrogen utilization.Excess
rumen degradable protein results in increase concentration of rumen ammonia which is transported to liver
and is converted into urea.Plasma urea commonly used for monitoring protein
status and intake.The MUN target concentration for lactating dairy cows ,target
N ranges from 150 to 200 g/d.MUN concentrations are 8.5-11.5 mg/dl.High milk
yield in dairy cows depends on high intake of dietary protein (17-19% crude
protein) and energy.
In Hematocrit (packed cell
volume),low haematocrit reflects suboptimal energy and protein nutrition.PCV ,
haemoglobin and serum iron are higher in non lactating animals than in
lactating animals.It varies with lactation stage and is high in dry cows and lowest in early
Serum inorganic phosphorus:- Serum inorganic phosphorus levels tends to fall
following long term insufficient dietry intake. Hyperphosphatemia occurs
in cattle grazing on highly fertilized pasture.
Serum calcium:-These are not much sensitive indicators of input
output balance.However, abnormally low levels in late pregnancy indicates a
Serum magnesium:-Serum magnesium levels are low during winters and Sudden
fall in temperature can leads to clinical or sub clinical hypomagnesemia. Supplementation
of diet with magnesium salt is protective.
Timings of blood tests:-
§ In relation to feed change
§ In relation to feeding
§ In relation to calving pattern and seasonal feeding
Selection of cows:-The rules for metabolic profiling of dairy cattle
recommended sampling from the following groups:-
§ Early lactation (EL) : between 10 and 20 days of
§ Mid lactation (ML) : between 50 and 120 days of
§ Dry period (D) : between 7 and 10 days of calving
Individuals variations in
biochemical values are such that single cow should not be tested. Groups of no
less than five should be sampled.
BODY CONDITIONING SCORE (BCS): this is the Subjective method for accessing amount of metabolized energy
stored in fat and muscle. The Scoring is done using 0-5 scale-
1. Score 0
2. Score 1
3. Score 2
4. Score 3
5. Score 4
6. Score 5
production and management-N.S.R.Sastry,C.K.Thomas
National Dairy Development Board.
Journal of dairy scienceJournal of Animal scienceIndian