Animal nutrition - feeding and milk Flashcards
Milk is a nutritious feed/food for a newborn, but additionally also has various other
physiological functions: (3)
– protective function of the organism (immunoglobulins,lysozyme and other antibacterial compounds)
– develops and supports the functions of the digestive system (enzyme inhibitors)
– contains growth factors/hormones
Factors affecting milk composition (4)
- Genetic factors
- Disease related factors
- Physiological factors
- Feeding related factors
Fat,% heritability is up to
0.5 (depends on breed), is negatively correlated with milk production (r = -0.3)
This simplest technique takes into account heritability of the trait and increases the frequency of the desired gene in the herd. At the same time the gene is unknown.
Protein,% heritability is
0.5
(The following are Positively correlated:
– fat and protein concentration (r = +0.5)
– milk, fat and protein yield (r = +0.9))
2 genes are known to affect milk coagulation by affecting what milk proteins?
k-casein and β-lactoglobulin affect milk coagulation
example of Molecular genetic manipulation for improving milk composition
transgenic cows by recombinant DNA injection into the embryo
Milk with high SCC means
high somatic cell count
Milk protein contains what 2 main protein fractions
Total casein
Whey protein
high somatic cell counts/mastitis cause milk to have more of what fractions? (3)
whey protein
sodium
chloride
name 4 Physiological factors that affect milk composition
Stage of lactation
Breed and breeding value
Season (associated with feeding)
Animal age
F % & P % are highest at
parturition
F % & P % are at a minimum, when?
3rd- 4th lactation month and then rise again
FA composition also changes.
in which seasons are fat and protein % lower and in which higher
in summer F & P% of milk are lower than in winter. the
higher temps results in lower feed intake.
digestion of fiber produces a lot of what which would affect milk production negatively?
digestion of fibre much heat is released
so in summer milk production is decreased
animal age causes what type of change in milk composition?
the F % and P % fall
milk solids decline
the fastest way to affect milk composition
Changes in feeding
We can manipulate practically all milk
ingredients.
With feeding, what about milk fat can we affect? (2)
– the milk fat content and
– FA composition of the milk fat
To change milk fat composition, you need to know (2)
– how the milk fat is synthesised, and
– what affects it
Milk fat mosotly contains
triglycerides
Glycerol needed for milk fat synthesis is synthesised in the
udder glandular tissues
Glycerol needed for milk fat (triglyceride)
synthesis is synthesised from (2)
– either from blood glucose or
– from propionic acid in the liver
Required milk FAs are synthesized in the
at least half are synthesised in the udder glandular tissue
All short chain and some medium chain fatty acids (up to C16) are synthesised how and from what? (2)
synthesised de novo from
acetic acid (90%) and
butyric acid (10%)
when is butyric acid especially utilized for milk fatty acid synthesis?
especially right after calving
Some medium chain (C16) FAs and the long chain FAs are incorporated into
the composition of the milk fat.
Where are the components derived from? (2)
– either from free FAs in blood, which originate from body fat, or
– from dietary fat, which is transported with lipoproteins into the udder
what % of fatty acids are derived from blood FAs
60%
what % of fatty acids are derived from de novo udder synthesis
40%
60% of milk fatty acids aare synthesized from “blood-borne” fatty acids.
what percentage are derived from dietary fats and what percentage from body fat?
Fatty acids from dietary fat (80%)
Fatty acids from body fat (20%)
milk fat composition main 3 components and their percentages
- Triglycerides or triacylglycerol -> 95.80%
- Diglycerides or 1,2-diacylglycerol -> 2.25%
- Monoglycerides or monoacylglycerol -> 0.08%
milk fat additionally contains what? (3) (other than glycerides?)
- In addition
– Phospholipids 1.11%
– Cholesterol 0.46%
– Free FAs 0.28%
the main saturated fatty acid in milk is
palmitic acid
palmitic acid is the main fatty acid in milk. which other 2 are most common
stearic acid (saturated 18:0)
myristic acid (saturated 14:0)
the most abundant monounsaturated fatty acid in milk?
oleic acid C18:1
polyunsaturated fatty acids in milk
linoleic acid (C18:2 omega-6) 2.0 g/100g
alfa-linolenic acid (C18:3 omega-3) 0.3 g/100g
milk fatty acids are mostly synthesised from what acid
acetic acid
Microbial population and rumen pH
determine milk fat synthesis
what type of carb is needed to increase acetic acid production for milk fat?
Fibre -> cellulolytic bacteria -> acetic acid
pH 6.0-6.5
Microbial population and rumen pH
determine milk fat synthesis
what type of carb is needed to increase propionic acid for milk yield?
Starch -> amylolytic bacteria -> propionic acid
pH 5.5-6.0
Microbial population and rumen pH
determine milk fat synthesis
what type of carb is needed to increase butyric acid for milk fat content?
Sugar -> saccharolytic bacteria -> butyric acid
pH 5.0-5.5
Reasons for low milk fat content connected to feeding.
According to current understanding these can
be of four groups:
- Feeding too much unsaturated fatty acid
- Low rumen pH (too acidic)
- Combination of the above two
- Feeding too much saturated fatty acid
how does the Biohydrogenation in the rumen change if the ration contains a lot of highly degradable carbs/CH-s (lower rumen pH) and/or UFA (oils)?
lecture 13, slide 23
how is effective fiber in the ration related to ruminal pH
An increase in the amount of effective fibre in the ration stimulates production of endogenous buffer (saliva)
▪ better as sharp and prickly hay or straw, increased stimulation of salivation with rumination
how should ration starch and sugar conent be adjusted in case of high ruminal acidity
should be decreased
▪ maximum of 300 g/kg in DM
how should ration ruminally fermentable starch content be adjusted in case of high ruminal acidity
Decrease proportian of ruminally fermentable starch in the ration
▪ barley > wheat/rye/triticale > oats > maize
▪ high moisture grain vs. meal vs. rolled or cracked grain
name 2 types of exogenous rumen buffers that could be used in case of needing to adjust ruminal pH with a supplment
add soda at 500g/day, or Magnesium oxide / MgO etc.
how does mixing various cereals aid in keeping rumen pH reasonable as opposed to feeding one type of cereal on its own?
fermentation time-point widens versus lots of fermentation happening all at once/ peaking
If the rumen pH is lower and the ration simultaneously contains more UFA-s, then the
effect on milk fat content is
negative effect on milk fat content is higher
If the ration DM amount of starch+sugars exceeds 300 g/kg and unsaturated FA-s exceeds 25 g/kg milk fat %
milk fat % decreases
There are a number of enzymes in the udder that make saturated fatty acids
liquid again at body temperature
Why are there enzymes in the udder that change saturated fatty acid melting point?
This is necessary so that the milk fat can come out of the udder gland cells into the alveoli as obviously solids cannot be secreted.
There are a number of enzymes in the udder that make SFA liquid again at body temperature. This is necessary so that the milk fat can come out of the udder gland cells into the alveoli.
What fatty acid is the one exception to this?
palmitic acid
Fat in the feed reduces the fat % of milk, however one fat exception is palm fat.
It has been found that feeding cows up to 0.5 kg of palm fat per day increases both what?
-> milk yield and milk dry matter content (fat & protein)
However, it is not sensible to feed it at the beginning of lactation -> milk production increases, but this is achieved mainly due to body reserves -> lower blood insulin and higher NEFA levels (Non esterified fatty acids) in the blood
Animal health is most impaired if the reduction in milk fat content occurs due to
lowering of ruminal pH and disturbed digestion -> acidosis
Low milk fat content leads to higher milk yield,
because
the cow spends 2.5 times more energy on
fat synthesis than on lactose synthesis.
If the ration contains crude fat at more than 70
g/kg in DM, milk production
decreases.
According to the latest recommendations the
dietary fat content should not exceed
50g/kg in DM
(of which UFAs should cover half)
milk protein fractions and their percentages (3)
- Casein proteins – 78%
- Whey proteins – 17%
- Non-protein nitrogen – 5%
the casein protein fraction of milk protein can be further divided into (4)
alfa S1–casein 34%
alfa S2–casein 9%
β-casein 25%
γ-casein 3% (breakdown product of β-casein)
k-casein 9%
the whey protein fraction of milk protein can be further divided into (5)
–β-lactoglobulin 8.5%
–α-lactalbumin 2.8%
–serum albumin 0.7%
–immunoglobulins 2.3%
–proteases, peptones 2.7%
the Non-protein nitrogen protein fraction of milk protein can be further divided into (6)
–Urea-N
–Amino-N
–Peptide-N
–Creatine-N
–Creatinine-N
–Ammonium-N
–etc.
Non-protein nitrogen contains 20-75% of
urea-Nitrogen
What proteins are synthesised in the udder glandular tissue?
All casein proteins and some whey proteins (β-lactoglobulin and α-lactalbumin) are synthesised in the udder glandular tissue.
(not 1 hundo % certain this is correct/ slide had bad english)
serum albumin and immunoglobulins are synthesised in the liver
and transported into milk directly from blood. to what milk protein fraction do they belong?
whey proteins
Casein and whey proteins are synthesised from
amino acids in the blood
Milk protein content depends on the amount and profile of
free AAs in the blood, and their suitability for milk protein synthesis
AAs in the blood originate from (3) and at what percentages
from micro-organisms (60%)
feed (30%)
and the body (10%)
If the AA content in the blood is low the cow
first synthesises what proteins?
body proteins first and after that milk protein
The higher the milk production is, the higher
must be the
rumen undegradable protein content in the ration
– for example: a 600kg dairy cow’s ration must
contain rumen undegradable protein at:
25 kg milk production 27% protein needed
35 kg 36%
45 kg 41%
using only microbial protein, a cow can produce at max enough milk protein for a milk yield of?
milk protein only for 20 kg of milk yield
Why is it impossible to change the
milk protein composition with feeding?
it is genetically determined
however, we can change the milk protein quantity
what proportion of free AAs in the blood origniate from microbial protein
60%
Therefore:
1. we must maximise rumen microbial protein
synthesis
- pay attention to the quality of dietary protein
Microbial protein synthesis depends on
the availability of energy and protein for the rumen micro-organisms
Usually, ruminally fermentable energy is limited
for microbial protein synthesis, when rations
based on
grass and/or leguminous silages are used
what do we want to increase in the ration to increase microbial protein synthesis?
starches so ruminally degradable energy sources/grains
suitable are barley, wheat (up to 50%), rye (up to 20%), triticale; less oats
why do we not want to feed too many oats?
abundent oats can produce lots of “glueing proteins” which can glue the abomasal leaves together so-to-speak
How does feeding effect milk protein content?
It doesnt really as its genetic - only if its super deficient in portein.
How many AAs pass into the small intestine (30%) depends on the protein feed in the ration which in turn depends on the production technology of the feed.
Effective degradability % and metabolizable protein are the main things to remember.
protein feed quality depends on how it was
produced/ processed
e.g. heat-treated rapeseed cake effective degradability % is lowered than that of cold-pressed
we want the feed protein to make it past the rumen to the abomasum and small intestine
What is the effect of feeding dietary oil fats on milk protein content?
more oil feeing generally decreases milk protein content
▪ oil feeding decreases microbial protein synthesis in the rumen
(double bonds are toxic to microbes)
▪ decreases blood flow through the udder
What is the effect of feeding higher fatty acid amounts on milk protein content?
increases milk and milk protein yield
▪ higher FA amount in the blood reduces both FA de novo synthesis and acetic acid oxidation in the udder, and therefore more glucose remains, which results in an increase in milk and milk protein production
Why does oil feeding decrease microbial protein synthesis in
the rumen?
double bonds are toxic to microbes
higher FA amount in the blood reduces what two things?
reduces both fatty acid de novo synthesis and acetic acid oxidation in the
udder,
therefore more glucose remains, which results in an increase in milk and milk protein
production
100g of microbial protein and 100g of
by-pass protein feed are not equal
which is better for milk protein production?
microbial protein because the amino acid composition is very similar to that of milk protein
Lactose content in different milk is
2-8%
Lactose content in cow milk is
4.8-5.0%
describe Lactose
is a disaccharide
– β-D-galactopyranosyl
– 1,4-D-glucose
– between is β-1,4 glycosidic linkage
In addition to lactose, milk also contains small amounts of what sugars (3)
glucose, galactose and oligosaccharides
Lactose is synthesized in the udder from
blood glucose
in the udder gland cells, half of the glucose molecules are converted to
galactose
galactose and glucose molecules are bound together using the enzyme
lactose synthetase
it is practically impossible to change the milk lactose content by?
feeding
lactose content typically remains pretty constant always
What is the main osmotic pressure agent in the udder and always transports a specific
amount of what from the udder into the milk?
Lactose is the main osmotic pressure agent in the udder and always transports a specific
amount of water from the udder into the milk.
If blood glucose content is low, this decreases what?, but does not affect the milk what? content.
If blood glucose content is low, this decreases milk yield, but does not affect the milk lactose content.
If blood glucose content is high milk yield is affected how?
but it does not affect what content?
if blood glucose content is high, milk yield increases
but it does not affect the milk lactose content.
what percentage of blood glucose is produced by gluconeogenesis in cattle?
90%
Gluconeogenesis in the liver -> 90% but from what substrates at what percentages?
– propionic acid (produced in the rumen) > 50%
▪ barley, wheat, rye, triticale (amylose)
– AA deamination (muscles, feed) < 30%
▪ alanine and glutamine are the major AAs for glucose synthesis (40…60%)
– adipose tissue (glycerol) < 20%
Main substrate for gluconeogenesis in cattle?
Second main substrate for the same?
propionic acid (produced in the rumen) > 50%
AA deamination (muscles, feed) < 30%
▪ alanine and glutamine are the major AAs for glucose synthesis (40…60%)
What percentage of By-pass starch is absorbed where and from what type of sources?
By-pass starch, which is absorbed in the small intestine -> 10%
▪ maize, potatoes (amylopectin)
With feeding, the easiest fractions of milk to change are (2)
the milk fat content and fatty acid composition
With feeding, which two fractions of milk are not so easy or not at all possible to change?
less so the milk protein content; the lactose content is practically impossible to change!
(the milk fat content and fatty acid composition are the easiest to change with feeding)
With increasing the feed intake,
milk fat content will?
milk protein content will?
milk fat content will increase
milk protein content will increase
With Decreasing the feed Intakeor low feeding level,
milk fat content will?
milk protein content will?
milk fat content will decrease
milk protein content will decrease
With Increasing the number of feeding times,
milk fat content will?
milk protein content will?
milk fat content will increase
milk protein content will increase slightly
With Increasing the concentrates content,
milk fat content will?
milk protein content will?
milk fat content will decrease
milk protein content will increase
With Increasing the fibre content,
milk fat content will?
milk protein content will?
milk fat content will increase
milk protein content will decrease
With Short length of roughage particles in feed,
milk fat content will?
milk protein content will?
milk fat content will decrease
milk protein content will increase
With Unstructured fibre in feed,
milk fat content will?
milk protein content will?
milk fat content will decrease
milk protein content will increase
With Increasing the amount of protein feed,
milk fat content will?
milk protein content will?
milk fat content will not be effected
milk protein content increases when in deficit
With decreasing the amount of protein feed,
milk fat content will?
milk protein content will?
milk fat content will not be effected
milk protein content decreases when in deficit
With Feeding with plant oils and oil-rich cakes,
milk fat content will?
milk protein content will?
milk fat content tends to reduce
milk protein content tends to reduce
With Feeding with rumen-inert fat,
milk fat content will?
milk protein content will?
milk fat content Tends to reduce
(if C16:0 is fed, then tends to increases)
milk protein content Tends to reduce
(if C16:0 is fed, then tends to increases)
An inappropriate AA profile may increase the milk what
urea
Milk fat to protein ratio is a cow’s energy balance indicator and should be between
1.1- 1.4
During NEB a lot of body fat will be used for the synthesis of
milk fat
– feeding rumen inert fat (C16:0) will contribute to this
Milk fat to protein ratio over 1.4 indicates
> 1.4 -> indicates energy deficiency, associated with ketosis (problematic at the beginning of the lactation)
Milk fat to protein ratio less than 1.1 indicates
< 1.1 -> indicates rumen acidosis
▪ Ration contains too much concentrate ->
low rumen pH (high UFA),
decreases F% (may be lower than P%)
When genetic methods are used, changes in
milk composition are …
A. long-term or
B. short-term
A. long-term
How does feeding of dietary fats affect a dairy cow’s milk fat content?
A. Increases in all cases
B. Increases in most cases
C. Decreases in all cases
D. Decreases in most cases
D. Decreases in most cases
If milk protein content is low, then what
should we do first?
A. maximise rumen microbial protein
synthesis or
B. pay attention to the quality of dietary
protein
A. maximise rumen microbial protein
synthesis
The milk yield is higher when the …
A. blood glucose content is low or
B. blood glucose content is high
B. blood glucose content is high
