Animal nutrition - calves & heifers Flashcards
the costs of rearing young cattle form about ?% of milk production costs
20…25% of milk production costs
For young stock rearing two things must be
controlled and followed:
- feeding scheme during rearing
- insemination age
these are both limited by biological aspects and affect future milk performance
in calves, the rumen volume contributes only what percentage?
25%
Rumen wall is smooth, slightly transparent and thin in newborn calves.
Rumen + omasum are 2 times smaller than the abomasum.
at week 10-12, calf forestomachs and abomasum volume are
fore-stomachs 14 l and abomasum 7 l
Protein digestion in calves.
Up to 4 weeks of age, what enzyme dominates?
rennin-cathepsin digestion
rennin-cathepsin do what to milk proteins
rennin coagulates and
cathepsin hydrolyses milk proteins at pH 5
what activates cathepsin?
lactic acid
lactic acid bacteria use what as substrate in calves?
lactose
then they produce necessary amounts of lactic acid to activate cathepsin
At the age of one month, what digestion starts in calves
At the age of one month HCl-pepsin digestion starts
– pepsinogen -> pepsin + HCl; works at pH 2
– activity of HCl-pepsin digestion increases with
addition of solid feed into the ration
cells producing HCl in the stomach develop at what age
cells producing HCl in the stomach develop at 31 days
of life
– rapid decline occurs after weaning
Pancreatic protease activity is what at birth
Pancreatic protease activity is low at birth
– a few days after birth activity begins to
increase rapidly
similar Pancreatic protease activity to the adult is achieved
8…9 weeks after birth
How well is Milk protein digested in calves
Milk protein is digested well ( >95%)
NB! the digestibility of vegetable proteins used in whole-milk replacer is much lower, and
therefore should not be used on first month
Fat digestion in calves.
Lipase is present in the saliva up to the end of
the
3rd month of life.
– lipase activity is greater if calves drink milk from
a teat
Calf Saliva lipase hydrolyses what length fatty acids very actively
Saliva lipase hydrolyses FAs C4 to C10 very actively
Calf Saliva lipase hydrolyses what length fatty acids less actively
Saliva lipase hydrolyses FAs C12 to C14 a bit less
– does not hydrolyse longer chain FAs
Salivary lipase activity is optimal at pH
4.5-6.0 and this occurs primarily in the milk coagulate
The main fat digestion in calves, occurs where by what
The main fat digestion occurs in the small
intestine by the pancreatic lipase
The main fat digestion in calves, occurs where by what
The main fat digestion occurs in the small
intestine by the pancreatic lipase
Calves digest fats generally well:
– short C-chain FAs (up to C10) absorbed already where at a rate of?
in the abomasum at a rate of 100%
Calves digest fats generally well:
– medium C-chain FAs (C12-14) absorbed where at a rate of?
in the small intestine at a rate of 95%
Calves digest fats generally well:
long C-chain FAs (C16 and more) absorbed where at a rate of?
in the small intestine at a rate of 80…90%
Milk fat is digested well by calves. At what rate?
100%
– in whole-milk replacers prefer short chain FAs,
vegetable fats can be used, but must be homogenised
Main Carbohydrate digestion in calves occurs in what by what
in the small intestine by the enzyme lactase
The activity of lactase is lower in what week of life
The activity of lactase is lower in the first week
of life, then increases and remains stable by 8
weeks of life, and then drops again
Digestion of other di- and polysaccharides,
besides lactose, is how in calves?
is limited in young calves, because they don’t have suitable enzymes (e.g. amylase, sucrase), or their activity is very low and not comparable to piglets
Colostrum compared to normal milk contains higher
DM, protein, fat, vitamins and minerals
obv contains a relatively high amount of albumins
and globulins
Colostrum protein composition is close to
blood protein composition
Colostrum acidity is?
and promotes?
high, and promotes coagulation of casein
Colostrum contains what type of inhibitors to prevent hydrolysis of?
contains trypsin and chymosin inhibitors to
prevent the hydrolysis of immunoglobulins
Colostrum contains what minerals more than
normal milk
Colostrum contains more Mg, Ca and P than
normal milk
Mg has a laxative effect, which helps to remove what in calves
the meconium
What vitamins are necessary for the calves during the first hours of life, but their transport through the placenta is blocked
Vitamins A and E
Thus, calves have practically no reserves of
these vitamins at birth. Therefore, the colostrum must be rich in these vitamins.
Depends on dry cow feeding!
Immunoglobulins are absorbed into the calves blood when?
1…3 hours after the first drink
▪ after 6 h, absorption is reduced by 50%
48 hours after birth the concentrations of Ig in
the blood must be
> 10 g/l
Milk composition normalises ? days after calving
Milk composition normalises 4…5 days after
calving
Ruminal papillae develop better if what is fed
Ruminal papillae develop better if starchy
concentrates are fed, rather than if hay is fed
Propionic acid (grains) promote development of
rumen papillae more than
acetic acid (roughage)
Butyric and lactic acids promote development of
rumen papillae even more, but they contribute to
acidosis (incl. metabolic).
Lactic and butyric acids are metabolised partly
in the
rumen wall and provide energy for rumen
epithelial cells
Hay and other fibre-rich feeds (dry silage) help
to develop (3)
rumen motility, stimulate saliva production and foster ruminal microflora formation
Whole-milk contains in what % protein and
fat in DM?
25-27% protein and
29-32% fat DM
Milk replacer should contain what % protein and
fat in DM?
➢20-24% protein of which at least 30-35% is casein
proteins, and
➢18-20% fat
Unfortunately, traditional milk replacer doesn’t
contain enough
protein to support tissue growth
Due to this concentrate (starter) feed is essential,
start with this instantly after colostrum period.
High amount (> 10 litre) of milk-based feeds reduces
starter feed intakes.
Today’s Holstein calf’s energy and protein
requirements are neither met by whole
milk nor milk replacer so this means
Good starter feed is very important!
Starter feed should contain in DM: metabolisable energy ? MJ
13 MJ
– crude protein 19%
– crude fat 4%
– neutral detergent fibre 17%
– calcium 0,8%
– phosphorous 0,4%
When to wean calves?
2…2,5 month of age
Concentrate intake ≥ 1.5 kg
– at least 1% of their body weight
What weight to wean calves at?
≥ 85 kg
Chest circumference ≥ 95 cm
Concentrate intake ≥ 1.5 kg
– at least 1% of their body weight
Feeding of heifers.
during the first year of growth the ration
protein content must be
higher,
then the heifer will not get fat in the second year of growth too
Unfortunately, as body protein content
increases also does the
body’s fat content, but with feeding it is possible to affect the body’s fat and protein ratio
Puberty depends on the growth rate. Usually
at about what age
9 months
thus, puberty is determined by body weight,
not age
heifers will start to regularly come into heat
when their body weight is ca’
275kg (46% of adult body weight)
Growth rate before puberty must be?
And after?
before puberty, faster, about 900 g per day
after puberty this must be slower,
about 700 g per day
Age at first insemination depends on
growth rate, recommended at weight ca’ 380kg
(at age ca’ 14 month)
Animal growth rate after insemination must be
300g per day without increment of gestation
tissues
heifers’ optimal age at first calving is
24 months
Udder growth and development during the heifer
rearing period largely determines
the cow’s later ability to produce milk and lactation persistence
Energy level in the ration affects what 2 factors involved in heifer development
secretion of hormones and udder development
– if the ration energy content is low the development
of the udder glandular tissue will be delayed
– and in contrast, if the ration energy content is
high the glandular tissue of the udder will become overfat, especially when heifers are overfed during puberty
In the first month of life calves’ digestion tract is comparable …
A. to monogastric animals
B. to ruminant animals
C. partly to monogastric animals
C. partly to monogastric animals
At what time should colostrum be fed after birth?
A. This is not important
B. During first three hours
C. From 3 to 6 hours
B. During first three hours
For proper forestomach development:
A. hay is essential and starter feed is
recommended
B. starter feed is essential and hay is
recommended
C. milk feed is essential and starter feed
together with hay are recommended
B. starter feed is essential and hay is
recommended
Which period in the heifer’s life is most critical from an economic point of view?
A. From weaning to 9 months of age
B. From 9 to 15 months of age
C. From 16 to 23 months of age
D. Last month of pregnancy
A. From weaning to 9 months of age
The daily growth rate of heifers after puberty must be either…?
A. Greater than before puberty
B. Less than before puberty
B. Less than before puberty
When is the best time to inseminate heifers?
A. 9th month of life
B. 14th month of life
C. about 275 kg in weight
D. about 380 kg in weight
D. about 380 kg in weight
