Fernando Grasso » 2.Cattle management

Dairy cow management

Dairy production cycle. From UK Agricolture, modified.

Dairy cow housing

Loose systems for dairy cows.

Dairy cows housing

Differences between the two systems
Normally, the udder of the cows housed in cubicles is cleaner. The incidence of lameness in cattle housed in straw yards tends to be lower than those kept in typical cubicle systems, but the incidence of trodden teats can be greater, particularly if the yard is overcrowded.
There are no production or cow welfare differences between straw yards and cubicles when both are well managed. The choice between straw yards and cubicles will therefore depend on farmer preference, expertise and economic considerations.

Meat production

Meat production cycle. From UK Agricolture, modified.

Beef cattle housing

Layout of a barn for beef cattle.

Reproductive management

Reproduction is a necessary and important part of milk production. Without regular calvings in the long run, there will be difficulties in producing the desired amount of milk. It is also important to produce sufficient heifer calves as replacement animals and allow herd size to be maintained or expanded.
Today it is most common to use artificial insemination (AI) instead of a bull. AI increases the control over the breeding and enables the dairy farmer to use sperm from all over the world, which increases the genetic gain. However, at the same time, it increases the need for good planning and well structured working routines.
Another way to get a cow pregnant is to use the embryo transfer technique. So far this is relatively uncommon, but it is expected to increase in importance. The main advantage with embryo transfer is that it is possible to generate more calves from a good cow than it is with AI.
Research has shown that suboptimal calving interval cause large economic losses to dairy farmers, second in importance only to mastitis. Milking cows in late lactation are less profitable due to the decline in production. A long calving interval means milking less profitable cows due to the decline in production, fewer calves and too many cows with low feed conversion efficiencies. Therefore, successful reproductive management has a significant impact on the herd’s overall performance and the net income.

Oestrus cycle

Cows are commonly said to show oestrus approximately every 21 days (20 days for a heifer).  After insemination, cows can either conceive or fail to conceive to that service. If a cow is pregnant after insemination, the corpus luteum will not regress, progesterone concentrations will remain high, and the cow will not return to oestrus.  Alternatively, if a cow is not pregnant after insemination, the corpus luteum will regress, plasma progesterone concentrations will decrease, and the cow will return to oestrus approximately 20-23 days after insemination.  Therefore, if a cow is observed in oestrus after insemination, it can be concluded that she is non-pregnant.

The use of oestrus detections methods in addition to visual observation (such as tail paint or chalk, activity meters, pressure sensors, etc.) can potentially increase the efficacy of oestrus detection and the identification of non-pregnant cows.

Heat detection

Signs of estrus in cattle. From: Cafre, College of Agriculture, Food & Rural Enterprise, modified.

Visual heat detection

Visual heat detection relies on manual observations in the barn. The cows and heifers shall be observed for oestrus two to three times per day and all observed heats be recorded whether the animal is bred or not. The records provide the manager with information to anticipate future heats, which will make it easier to distinguish if a cow is in heat or not. Most mounting occurs between 6 p.m. and 6 a.m., and it is therefore worth trying to check for heat during these hours. To facilitate the planning and record keeping, a cow calendar is often used. This can be either manual or computerised.

The disadvantage with visual detection is that it is very time demanding and requires people with the ability to observe the right signs. This is particularly important when there are no distinct signs of heat.

Timing of insemination

With artificial insemination, the timing of the insemination becomes important. The optimum time for insemination depends on when the ovulation occurs in relation to the heat and for how long the sperm is viable. There are mainly two rules for the timing of insemination. Traditionally the a.m.-p.m. rule was the one dairy producers followed. This rule dictates that cows and heifers first observed in heat in the morning should be inseminated late in the afternoon. Likewise, cows and heifers first observed in heat in the afternoon should be bred the following morning. This is still a good rule, but many producers have now successfully gone to once-a-day insemination. This rule dictates that cows and heifers first observed in oestrus in the afternoon or the following morning, should be bred late that morning.

Timing of insemination

Cow typical behaviour during heat stage and optimal time of insemination.

Pregnancy diagnosis in cows

In both beef and dairy cattle, pregnancy diagnosis is an important tool to measure the success of a reproductive management, to allow for early detection of problems and to achieve resynchronization of non-pregnant cows.  More reliable methods for detecting early pregnancy in cattle are:

• Non-return to oestrus;
• Milk or plasma progesterone;
• Ultrasound examination;
• Rectal palpation.

Pregnancy diagnosis in cows

Non-return to oestrus
If oestrus signs are not observed around 3 weeks after service or insemination, the cow is generally assumed to be pregnant.
Relying on oestrus detection to diagnose pregnant cows is very unreliable, due to:

• If oestrus detection is not properly performed, many non-pregnant cows will not be observed in oestrus and will erroneously be considered pregnant. About 50% of dairy cows are not detected in oestrus when they are actually in oestrus.  This number increases during heat stress.
• Cows with reproductive problems such as ovarian cysts, uterine infections or anoestrus also fail to return to oestrus and may be misdiagnosed as pregnant cows.
• Pregnant cows can be mistakenly detected in oestrus and either re-inseminated (which would probably cause an abortion) or culled as a non-pregnant cow.

Pregnancy diagnosis in cows

Ultrasonography

An ultrasound machine resembles a radar device. A probe is inserted through the rectum and positioned above the uterus. This probe generates pulses of ultrasound that are transmitted to adjacent tissues. These pulses are then reflected back to the probe from different tissue surfaces. The reflected pulses to the probe produce an electrical signal that is processed by a scan converter and displayed on a video monitor. On the video, the intensity of the ultrasound pulses returned to the probe is converted to different shades of grey, as compared to black and white. Structures that contain fluid (such as the fluid-filled placenta) absorb most of the ultrasound pulses and the result is a black image on the video screen. On the other hand, more dense structures (such as an embryo) are more ecogenic (i.e., have greater reflectivity) and result in a light grey or white image on the screen.
The main advantages of the use of ultrasound for pregnancy diagnosis are 1) the high reliability of the results that are generated and 2) the fact that pregnancy diagnosis may be conducted relatively early after insemination (i.e., as early as 25 days after insemination).
The main disadvantages of the use of ultrasonography are related to cost and time involved with the use of this technique. Ultrasound machines are expensive and it takes more time to perform a pregnancy diagnosis with an ultrasound machine than by rectal palpation.

Pregnancy diagnosis in cows

Rectal palpation
Palpation of the uterine contents rectally is probably the most commonly used method for pregnancy diagnosis.  Pregnancy diagnosis after insemination can be conducted as early as 30 days in heifers and 35 days in cows, although much practice is necessary to be able to determine pregnancy at that stage.
Several palpable structures are indicative of pregnancy. Due to accumulation of fluids within the pregnant uterine horn, one of the initial signs of pregnancy is a difference in size of uterine horns (i.e., uterine asymmetry). Also, it is possible to feel the slipping of the chorioallantoic membrane (foetal membrane) along the greater curvature within the uterus (i.e., membrane slip).
Rectal palpation has the advantage of being an accurate, fast, relatively cheap method that is less labour intensive as compared to the previous methods. Nonetheless, training is necessary and the exam should be conducted by a veterinarian or by an experienced herdsman.
The main disadvantage of rectal palpation is that it cannot be performed until later in gestation than some other methods. Some veterinarians are able to determine pregnancy by palpation as early as 35 days after insemination, but usually rectal examinations take place between 45 and 60 days after insemination to increase the accuracy of the exam.

Calving

When calving is approaching, the cow shows the following behaviour:

• exhibition of signs of restlessness;
• she remains by herself;
• tail switching increases, eventually she will hold her tail up or slightly extended;
• she may kick at her abdomen, or turn and look at her side;
• may lie down for short periods but doesn’t seem to be comfortable;
• alert–strange sounds or noises may get her attention.

As labour progresses:

• cow becomes increasingly restless;
• she may lie on her sternum, then on her side, stand up and in a short while lie down again;
• can’t seem to get comfortable;
• eventually, she will begin to lie on her side for extended periods;
• she may strain a little, then stand up and sniff the area she has been lying in licking and sniffing of foetal fluids is the beginning of her recognition of the foetus/calf after calving.

Calving

The pregnancy length in cattle varies according to the breed:

• Italian Freisian 280 d
• Brown 289 d
• Marchigiana 294 d
• Chianina 298 d

Colostrum

At birth, a calf’s immune system is not fully developed. Colostrum is vital food for newborn calves. Colostrum contains antibodies or immunoglobulins necessary to provide the calf with protection from disease.
Colostrum contains 22 percent solids, compared with 12 percent solids in normal whole cow’s milk. Much of the extra solid material in colostrum is immunoglobulin, but colostrum also is an important source of protein (casein), sugar (lactose), fat, and vitamins A and E.
As a general rule of thumb, a calf should receive 5 percent to 6 percent of its body weight as colostrum within the first six hours of life. That same amount should be fed again when the calf is about 12 hours old. After that time, absorbing the antibodies in colostrum becomes more difficult. At six hours after birth, calves absorb 66 percent of the immunoglobulins in colostrum, but at 36 hours after birth they are able to absorb only 7 percent of immunoglobulins.
Breed type and cow age affect the amount of colostrum a cow produces. Dairy breeds produce more than beef breeds and mature cows produce more than heifers.
Some cows don’t produce an adequate amount of colostrum. That means producers sometimes have to use colostrum from other cows or stored colostrum to ensure that each calf receives an adequate amount. For optimum results, colostrum should be collected from cows within 24 hours of calving and fed fresh. Colostrum also can be collected at calving, stored frozen and used at a later date.

Colostrum

Composition (%) of colostrum, transitional milk and milk.

Calf weaning

Calf weaning scheme.