Lecture 3.3 – case 4 milk
Self-study:
Cattle can be used for multiple productions of feed: dairy and meat.
- The current world cattle population consists in total of around 1.5 billion
head, of which about 18% are dairy cows. Of these dairy cows about 0.6%
are kept in the Netherlands.
- 656 million tonnes of milk every year, which 12 million tonnes in the
Netherlands.
- While the number of dairy farms is decreasing, the number of cows per
dairy farm is increasing. Meanwhile, the average milk yield per cow per
year is also increasing.
- mostly Fleckvieh and Brown Swiss are kept in the Netherlands The most
frequently kept dairy cow in the Netherlands, and the entire world, is the
Holstein Friesian breed.
meat producing cows:
1. Belgian blue
2. Blonde D’aquitaine
3. Piedmontese
4. Limousine
Dairy cows:
1. Holstein Friesian
2. Montbéliarde
3. Jersey
4. MRIJ
Moreover, the milk composition is very important for farmers since they are paid
for the total kilograms of protein, fat and lactose in the milk and thus their
income depends on it.
A cow is a polyoestrous species with an oestrous cycle of approximately 21 days
which starts at puberty at approximately eight months. This age can be regarded
as the age at which a cow first ovulates and can support a gestation without
negative effects.
The oestrous cycle has 2 phases:
1. Luteal: comprises a metestrus and a dioestrus. The luteal phase starts with
ovulation and lasts until the regression of the corpus luteum.
2. Follicular: comprises a proestrus and an oestrus. The follicular phase can
be defined as the period between the regression of a corpus luteum and
ovulation.
, At the end of the follicular phase, the cow will be in oestrus. During oestrus, the
cow shows some typical behaviours like mounting or standing to be mounted.
This oestrus lasts for about 15-18 hours, and ovulation will follow within the next
24-32 hours of the cycle. When the oestrous cycle of a cow has been initiated,
she is ready to be inseminated around the time of ovulation. The ideal time for
insemination is within the range of 24-36 hours after oestrous detection. The
average age at which a cow is inseminated is 15 months, which results in a first
calving age of approximately 24 months.
Conventionally a cow is dried off at approximately 42-60 days before calving.
After the dry period the cow will calve and start producing milk. This milk
production happens under the influence of the hormones that are released on
parturition. Likewise, suckling plays an important role in the release of hormones
and thus in the let-down of milk. Therefore, gestation and giving birth to a calf
are necessary to start up and provide milk production.
- After calving it takes 45-50 days to involute and 18-25 days to resumption
of the ovarian cycle.
- After 90 days a cow can be pregnant again.
Milk production needs a well-developed udder and mammary gland.
- The udder: in 4 quarters, with each quarter contains a separate mammary
gland and teat.
Development of mammary gland to produce and secrete milk:
1. Embryonic stage
2. Puberty
3. Gestation and parturition
4. Constant endocrine stimulation by gestational periods
After the initiation of puberty and during several subsequent oestrous cycles, the
mammary gland starts to grow and form a duct with alveoli. Furthermore,
prolactin and growth hormone are important hormones to provide more rapid
duct development. During late gestation, the alveoli of the mammary gland will
further develop into lobules.
milk production peaks shortly after parturition and from that moment will slowly
decline during the lactation period. Furthermore, the fat and protein levels follow
the opposite curve from that of milk yield. Both levels decrease shortly after
parturition and from the lowest point will increase during the lactation period.
Self-study:
Cattle can be used for multiple productions of feed: dairy and meat.
- The current world cattle population consists in total of around 1.5 billion
head, of which about 18% are dairy cows. Of these dairy cows about 0.6%
are kept in the Netherlands.
- 656 million tonnes of milk every year, which 12 million tonnes in the
Netherlands.
- While the number of dairy farms is decreasing, the number of cows per
dairy farm is increasing. Meanwhile, the average milk yield per cow per
year is also increasing.
- mostly Fleckvieh and Brown Swiss are kept in the Netherlands The most
frequently kept dairy cow in the Netherlands, and the entire world, is the
Holstein Friesian breed.
meat producing cows:
1. Belgian blue
2. Blonde D’aquitaine
3. Piedmontese
4. Limousine
Dairy cows:
1. Holstein Friesian
2. Montbéliarde
3. Jersey
4. MRIJ
Moreover, the milk composition is very important for farmers since they are paid
for the total kilograms of protein, fat and lactose in the milk and thus their
income depends on it.
A cow is a polyoestrous species with an oestrous cycle of approximately 21 days
which starts at puberty at approximately eight months. This age can be regarded
as the age at which a cow first ovulates and can support a gestation without
negative effects.
The oestrous cycle has 2 phases:
1. Luteal: comprises a metestrus and a dioestrus. The luteal phase starts with
ovulation and lasts until the regression of the corpus luteum.
2. Follicular: comprises a proestrus and an oestrus. The follicular phase can
be defined as the period between the regression of a corpus luteum and
ovulation.
, At the end of the follicular phase, the cow will be in oestrus. During oestrus, the
cow shows some typical behaviours like mounting or standing to be mounted.
This oestrus lasts for about 15-18 hours, and ovulation will follow within the next
24-32 hours of the cycle. When the oestrous cycle of a cow has been initiated,
she is ready to be inseminated around the time of ovulation. The ideal time for
insemination is within the range of 24-36 hours after oestrous detection. The
average age at which a cow is inseminated is 15 months, which results in a first
calving age of approximately 24 months.
Conventionally a cow is dried off at approximately 42-60 days before calving.
After the dry period the cow will calve and start producing milk. This milk
production happens under the influence of the hormones that are released on
parturition. Likewise, suckling plays an important role in the release of hormones
and thus in the let-down of milk. Therefore, gestation and giving birth to a calf
are necessary to start up and provide milk production.
- After calving it takes 45-50 days to involute and 18-25 days to resumption
of the ovarian cycle.
- After 90 days a cow can be pregnant again.
Milk production needs a well-developed udder and mammary gland.
- The udder: in 4 quarters, with each quarter contains a separate mammary
gland and teat.
Development of mammary gland to produce and secrete milk:
1. Embryonic stage
2. Puberty
3. Gestation and parturition
4. Constant endocrine stimulation by gestational periods
After the initiation of puberty and during several subsequent oestrous cycles, the
mammary gland starts to grow and form a duct with alveoli. Furthermore,
prolactin and growth hormone are important hormones to provide more rapid
duct development. During late gestation, the alveoli of the mammary gland will
further develop into lobules.
milk production peaks shortly after parturition and from that moment will slowly
decline during the lactation period. Furthermore, the fat and protein levels follow
the opposite curve from that of milk yield. Both levels decrease shortly after
parturition and from the lowest point will increase during the lactation period.
