Optimizing Calf Survival at Birth
By successfully weaning more healthy calves, you can increase milk production, reproductive performance and your farm's overall bottom line
Your milking herd of tomorrow starts with the calves born today, Let's take a closer look at the basics to getting replacements off to a sound start to become healthy, productive all-stars on your milking team.
In spite of advancing technology, dairy calf death losses remain alarmingly high, and have shown no signs of getting better. To improve your odds of raising healthy, productive herd replacements, your best bets are preventing and managing difficult births, and ensuring newborn calves get adequate immunity from colostrum. This strategy will improve your herd's milk production, reproductive performance and overall bottom line.
When successful, a dairy calf's birth starts a profitable lactation in the milking herd for the mother and a good start in life for another herd replacement. It is the culmination of several factors: careful planning of an ideal mating to produce an embryo that will become a milking herd replacement; dry cow management providing optimum conditions for both mother and newborn; and, in the case of a first-lactation cow, the result of 24 months of feeding, care and management before the event when she will take her place in the milking herd.
All too often, this scenario for success never occurs. Canada's stillbirth rate is 12 per cent for first-lactation births and seven per cent overall. About half the stillbirths can be attributed to difficult calvings, known as dystocia.
A difficult calving results in lost production, infection and poor fertility for the dam. Her calf may be weak and suffer from bovine respiratory disease or diarrhea. The calf, cow or both may not survive.
Pre-weaning death loss rates range from 7.8 to 11 per cent, 53 per cent of these losses due to scours and 21 per cent due to respiratory disease. A high proportion of illness and death in the pre-weaning period can be attributed to failure of passive transfer of immunity. The calves simply get insufficient immunity from colostrum early enough to fight off disease.
Dystocia is defined as a difficult or abnormal birth at any stage of labour. It is recorded on a scale of 1 to 4 in Canada, with 1 being a birth without assistance and 4 being the most severe form of dystocia requiring surgery. Dystocia levels reported in the 2007 U.S. Department of Agriculture National Animal Health Survey (NAHMS) are higher for first-calf heifers at 19 per cent than for second and later calvings at 11 per cent. It may be under-reported by dairy producers and more widespread than survey data indicate.
Stillbirth, defined by Canadian genetic improvement statistics as the death of the calf at birth or within 24 hours after delivery, occurs in 12 per cent of calvings for first-lactation cows and six per cent of calvings for those in second and later lactations. Half of stillbirths can be attributed directly to dystocia, and the odds of a calf dying within 24 hours of birth are much higher following a difficult calving.
Reasons for dystocia in first-lactation births tend to be related to large fetal size, but in later lactations dystocia is due more to malpresentation-an abnormal positioning of the calf before birth - or dam-related issues. Dystocia has a profound negative impact on calf health and survival, reducing future dairy productivity.
Calving management and procedures can greatly minimize losses due to dystocia and stillbirths. They include:
- keeping good records of breedings and expected calving dates;
- having a clean, dry calving facility not used as a sick bay as well;
- knowing calving signs;
- knowing when to intervene to provide assistance;
- knowing calving assistance procedures;
- ensuring newborn calves get adequate colostrum as soon as possible after birth to achieve passive transfer of immunity.
Your breeding strategy is a key factor to ensure successful calving. Since the incidence of dystocia and stillbirths in first-lactation calvings is nearly double that of calvings in later lactations, you can reduce dystocia and stillbirths through sire selection to take advantage of genetic variation.
Choose sires to breed heifers that are ranked above average for calving ability, a combination of calving ease and calf survival. Sires are ranked according to calving ability and daughter calving ability. For a heifer sired by a bull rated low for daughter calving ability, take extra care near calving time to ensure successful delivery. Consider sex-sorted semen for breeding heifers, since bull calves born to heifers result in a high incidence of dystocia and stillbirths.
Passive immunity transfer
The next critical time in the newborn calf's life is birth to weaning. Preweaning mortality rates range from 7.8 to 11 per cent. Thirty-one per cent of those deaths in the first three weeks of life have been attributed to failure of passive transfer (FPT) of immunity from the dam. The only way a calf can get immunity after birth is through colostrum. The U.S. NAHMS survey indicates 21 per cent of calves have FPT, meaning a serum immunoglobulin (IgG) level of less than 10 milligrams per millilitre.
Key to achieving optimum IgG levels are the three Qs: quality, quantity and quickness. Feeding high-quality colostrum in the right quantity quickly after birth will greatly improve a calf's chances for survival and good health. The newborn's ability to absorb immunoglobulins through its gut wall decreases rapidly during the six hours after it's born.
Dystocia and letting the calf suckle on its own have been shown to contribute to FPT. Calves born unassisted but allowed to suckle on their own also tend to have FTP. They probably do not receive first colostrum in a timely manner.
New tools developed
A large amount of information available on protocols and procedures has been demonstrated to improve calf survival. Most are simple lists. However, keeping simple records and implementing these protocols routinely in the calving pen has always seemed challenging.
Research in Quebec and at the University of Guelph's Ontario Veterinary College (OVC) is addressing some of these issues. A Quebec study, conducted with co-operating dairy farmers, developed and evaluated an advisory tool to improve calf and heifer management practices. Similar OVC work is assessing calf vigour at birth and developing protocols for calf management.
An alarming number of calves die at or near birth, and an equal number suffer from less-than-optimum health after they are born. Having protocols and procedures in place for pre-calving, recognizing the signs of birth, following calving procedures and caring for calves immediately after birth can help you achieve successful calvings with low death losses and maximum calf survival and vigour.
Difficult calvings hurt your operation economically through lower production, reproduction, and calf and cow survival. An Iowa State economic study determined the total cost of dystocia for an average Holstein heifer is $28.53, while the economic loss associated with severe dystocia is $380. Relative losses are 41 per cent from lower production, 33 per cent from reduced fertility, 7.5 per cent from cow loss and 17 per cent from calf loss. With older cows, fertility losses become 65 per cent of the cost of dystocia and production loss becomes much less important.
Optimizing calf survival and welfare at birth involves breeding strategy, proper facilities, record keeping, recognition of calving signs, and using best practices around and during calving time. In a previous article I calculated the potential value of reducing Ontario's stillbirth rate to an optimum two to three per cent from nearly eight per cent overall. Some Scandinavian countries have achieved the lower rate.
Could Canada reach this level? I believe we can, but current statistics show we have not yet started to move in this direction. If we did lower calf losses to the Scandinavian rate, the difference would be 17,500 live calves valued at more than $4 million per year.
This article first appeared in the Ruminations column of The Milk Producer Magazine, December 2010.
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