Cow No 18 (suckler cow for a beef herd)
The dairy cow is the hardest working animal on the farm.
In order to produce milk, she will be inseminated, become pregnant and produce a calf. As a sequel she produces milk in order to feed her calf.
The normal and average life expectancy of the cow is from between 15 and 20 years. The modern dairy cow can expect to live for 6.5 years with an average of four lactations (the process by which milk is produced), though the target is for 6 lactations.
The cost of producing a cow is approximately #1100. This figure includes the feeding and maintenance of the calf from birth until the time of her demise.
Care of the cow includes regular drenching for internal parasites: worms and fluke and possibly pour ons for the treatment of lice.
Routine vaccinations for a variety of diseases include an oral lungworm vaccination, 5 in one for a variety of clostridial diseases or 7 in one including vaccine for leptospirosis are administered. Other vaccinations are for Bovine Viral Diahorrea, (BVD), Infectious Bovine Rhinotracheitis, and Johnes Disease. Pneumonia and Rotavirus.
Vaccination plays an important role in the control, dampening down and elimination of disease. The concept of vaccination, is that a small, controllable amount of a bacteria or virus is introduced into the body in order that the immune response is invoked. When the body next encounters the same antigen, it recognises the disease causing organism and the antibodies work to subdue and eliminate the disease.
There are however, concerns about the number of vaccines, the chemical content and the effect of multiple challenges to the immune system to an animal that already lives a stressful life.
The objective in dairy operations is to ensure high reproductive performance, combined with high milk yield. The breeds that excel at milk production are the familiar black and white cows: Friesians and Holsteins, a European import. Amongst suckler herds it is for reproductive performance, quality milk yield and the production of high quality beef, i.e. lean carcasses of good conformation.
For suckler heifers, an easy calving bull, such as a Limousine bull (French) for artificial insemination (AI) is often used. For mature cows, a large continental sire breed such as the Charolais may be used.
The pregnancy or gestation period in the cow is 282 days, which is a little over 9 months.
Parturition, which is the act of giving birth to the calf, is divided into
3 stages: First stage labour, lasting 2-6 hrs is when the uterine contractions result in dilation of the cervix, which is the neck of the uterus in preparation for the expulsion of the calf.
Second stage labour, is the actual delivery or expulsion of the calf from the uterus.
Third stage is the delivery of the placental tissue or afterbirth, which usually occurs immediately after the birth.
In a normal delivery the calf arrives front feet first with the head extended and the nose between the front feet.
In suckler cows dystocia (abnormal delivery) is often a problem due to a cow of small conformation being inseminated by an unsuitably large bull.
The cow may require a caesarean which may result in the loss of the cow or calf or both if there are complications.
Her entire lifestyle can be described by the following phases:
Milking and pregnant cow
After the birth the neonate calf should remain with its dam for 24 hours in order to maximise colostrum intake.
The majority of colostrum intake by the calf will be within the first 6-8 hrs of its birth. If the calf is removed from the cow at birth, it leads to lower colostrum levels, which results in increased risk of disease throughout her life. Removal from the cow, in order that she does not suck her dam, but remains in her presence, results in increased colostrum intake. In this instance the colostrum is milked from the cow and fed to her calf.
The calf may never meet her dam and no bonding is allowed to take place. On some farms this is considered preferable to the bawling that otherwise occurs when the cow and calf are separated after the 24-hour period.
The calf is then frequently fed a bought in powdered milk that the farmer supplies to it, via a feeding system fitted with a teat. Old-fashioned farming systems used buckets that did not enable calves to satisfy their sucking reflex with resultant stereotypic behaviours such as navel and tail sucking. These behaviours can also be seen on modern farms, indicating that the natural behaviours have been limited or denied.
Weaning of calves from a largely milk diet is traditionally after 8-10 weeks. The more usual pattern on farms today is 5-6 weeks. The calves of suckler cows fare better. As these calves are the beef producers in 30 months time, they remain with their dams for at least that period of time.
The young calf (dairy) spends its time in the company of its peers. It receives no mothering and does not have access to the range of different aged animals that an individual living in a natural herd would do. Consequently it is not properly socialised and receives no discipline and no example of normal bovine behaviours.
Puberty, which is the period during which the reproductive organs become functional, occurs between 7 and 24 months of age in the cow. The actual age of puberty in individuals is dependent upon climatic conditions, breed, heredity, hormonal levels and nutritional status.
Heifers are young maiden cows that have not previously produced a calf.
On average she will require 1.65 services, either by a natural covering by the bull or by AI, in order to become pregnant.
The success rate for AI is 46% (national herd statistic).
The aim is for a 365-day calving index. That is each cow should produce a calf each year of her life. Profitable suckling in suckler beef herds is also dependent on the production of a live calf per cow per year.
After a pregnancy lasting a little over nine months, the cow must be got back in calf within approximately 60 days if the calving index is to be maintained.
On average, 90 live calves are born to 100 cows.
The mean age of the heifer at her first calving is between 23 and 28 months of age, but she should be no younger than 22 months and weigh no less than 630kg.
Heifers have lower immunoglobulins (antibodies) in their colostrum than cows, which is the result of less exposure to pathogens (disease causing organisms) in their environment and for a shorter time period than an adult cow experiences.
The obvious consequence is that her calf receives reduced levels of antibodies, which make it more susceptible to disease.
22-28% of heifers fail to reach calving age and 10 % are culled after first calving for failure to conceive.
Factors that affect fertility, which is the ability to get in calf and sustain the pregnancy, resulting in the birth of a live calf are: nutrition, length of the dry period, hormonal manipulation, seasonality (time of the year), induction of parturition, infections, defects in the egg or sperm and inherited lethal factors.
The Dry cow period is the rest or break that the cow has before calving and resumed milk production. The length of the dry period is between 6 and 8 weeks.
During this time the unborn calf is fast developing and the cow must maximise her body reserves in order to maintain the milk yield when the calf is born. This time also allows for the repair and growth of udder tissue and for her body to adjust from a plane of high to low and back to high nutrition again.
In the first 6-8 weeks after parturition her body reserves will supply the energy that produces milk (that is she makes milk off her back).
She will have on average just four lactations.
Her life yield is 18747+kg of milk.
Older cows produce more milk than heifers. Cows produce more than 42 litres per day, while heifers may be expected to produce 35 litres per day. At that production level it becomes difficult to see heats and difficult to get the cow in calf. The heat is the oestrus phase when the cow is sexually active and will soon be ovulating and will therefor stand for the bull or for AI.
The production of high levels of milk has a contraceptive effect, which is natures way of ensuring that the cow does not produce another calf while she still has such a demanding calf to feed.
Milk is produced over 11- 13 months with a calving interval of 330-395 days.
If she produces less than 12litres per day she is not producing an economic amount of milk relative to her feed intake and other costs associated with her keep and she will be culled. Mastitis, (inflammation of the udder with possible damage to the tissue, that will affect milk production) and ketosis (may be the result of over fat cows who are more susceptible to pregnancy toxaemia) are also reasons for culling. Both these problems are largely ones of management and therefor are avoidable reasons for culling.
Pendulous udders and the position of the teats can make feeding by the calf difficult (a problem in older cows and the result of selecting for milk production), are further reasons for culling. Large udders put strain on the ligaments of the back and hocks disposing the cow to lameness, which may also lead to culling.
In dairy herds 40%, nearly half, fail to calve a second time and are therefor culled.
54% by the 4th lactation
75% by the 6th lactation
84% by the 7th lactation
The majority of cows are culled for failing to become pregnant.
The lifestyle of the cow and her calf, that is how they are managed, when and how they are housed, whether they receive veterinary attention, what they are fed and when they will die, are at all times determined by economics and not welfare.
In 1994 the average diary herd size was 68, today it is in excess of 100.
Michaela Bowles 24th June 2001