Artificial Rearing of Lambs
Table of Contents
In many sheep flocks there are orphaned lambs and many prolific ewes have too many lambs for the milking ability of the natural mother. In many of these cases, the most natural and economical route is to foster these lambs. Artificial rearing should only be considered when the option to foster is impossible. However, in sheep milking operations lambs drain total marketable milk yield, and artificial rearing is a blanket option. Typically, this involves the use of a commercial substitute for ewe's milk, although some fortified mixtures of bovine waste milk have been used successfully. Another critical component is the rapid adaptation to solid feed. This will ease the lambs' dependence on human intervention and prove to be economical.
Clearly the greatest benefit is the production of additional lambs that would have been mortalities otherwise. Sometimes these extra or 'bottle lambs' have been euthanized, labeled as being troublesome and uneconomical. With a system in place to feed and raise these animals efficiently, increased profits and reduced welfare concerns can result. The key to success is a system that will allow sufficient resources, time and space, rather than ongoing haphazard artificial rearing.
Removing the lambs from the ewe and feeding milk replacer not only increases marketable milk, it may in fact improve total lactation milk production as the draw on the ewe maintains maximal milk synthesis. When milk draw is below this level, production begins to fall as production is tied to use patterns. Once production begins to decline, it will not recover.
The single most important aspect of any rearing system is the proper administration of colostrum. Ideally, a lamb should receive 50 ml per kg (1 ounce per pound) of bodyweight of its own mother's colostrum, within 1 hour of birth. Additionally, 150 ml per kg (3 ounces per pound) spread over three more feedings within the first 24 hours of life should be provided. This is to promote passive protection of the lamb until its own immune sytem is functioning. If the ewe has too little colostrum, there are other options. These are (listed in order of preference):
The longer the delay, the poorer the animal's ability to utilize the colostrum. Additionally, the quality of the colostrum secreted by the ewe rapidly drops towards normal milk production within hours of parturition. Colostrum administration/feeding at birth is the single most critical feeding and management point in the lamb's entire life. Using the immunity passed from mother to offspring, this is also an opportunity to pass on the antibodies from the vaccinations that the ewe has received to the lamb. Proper nutrition of the ewe during gestation will ensure adequate colostrum quality, and increases the likelihood of adequate quantities.
The milk replacer manufacturer's instructions specify a temperature for mixing to ensure the even distribution of fats in the reconstituted milk. Quite often, once the milk has cooled to about body temperature, it is fed to the lamb or kid. In many cases there will be no problem, but an increasing incidence of abomasal bloat has been reported associated with this practice. In some operations there have been quite significant death losses associated with artificial rearing from abomasal bloat.
The usual history of a lamb killed by bloat is that the lamb was fed milk replacer two or three times a day, and a considerable volume of milk was given at each feeding. The milk replacer was fed at about body temperature. Within 30 minutes the abdomen was bloated. Examination suggests that the ballooning is due to excessive gas in the stomach which kills the lamb within a few minutes. At postmortem the abomasum is grossly distended and may have ruptured. The rupture may have occurred prior to, or after, death. There are reddish areas in the wall; the rupture often occurs at these sites. In prepared sections of abomasal lining, small packets of cocci bacteria can be identified under the microscope. These packets of Sarcinia species bacteria are a common finding in cases of abomasal bloat but virtually never seen otherwise.
Even now the mechanism of this bloat is not fully understood. Originally, a common group of bacteria, the lactobacilli, were thought to be the cause; now the Sarcinia species are implicated. These bacteria are known to be fermenters and can multiply across a wide range of acidity in the abomasum. A large quantity of warm milk arriving in the abomasum provides an excellent medium for the rapid multiplication of these bacteria. As they multiply, sugars in the milk are fermented with excess gas production. At the same time the stomach contents become more acidic to the detriment of other bacteria. As the gas cannot escape, it bloats the abomasum which presses on the other internal organs, notably the heart and lungs. Death is from heart failure as a result of this pressure.
Once the bloat is visible, there are virtually no successful treatments. Occasionally, a lamb has been saved by relieving the bloat with a needle inserted into the abomasum to vent the gas.
As the condition is associated with bacterial populations, feeding and storing the liquid below 4°C (40°F) will usually stop any further cases. The milk replacer powder still has to be mixed with water at the manufacturer's recommended temperature, then cooled as quickly as possible in a refrigerator. To the producer, this means preparing the milk one feeding in advance of need; that is in the morning for the evening feeding. Some reports suggest that adding 1.0 ml of a formalin solution (37% formaldehyde) per litre of milk replacer is a preventative.
Another problem for the artificially reared lamb is sudden death from enterotoxaemia. Often it is the best growing lamb that is found dead with no previous symptoms. At post mortem, the only lesions to be seen grossly are reddish areas in the wall of the small intestine. There are microscopic changes to be seen in other organs, and tests can confirm the presence of toxins. The causal organism is a bacteria, Clostridia perfringens type D. This bacteria can be present in small numbers in the intestine, but, with the normal speed of movement of the ingesta through the intestine, there are insufficient organisms to cause disease.
In artificially reared lambs, there are three factors which may allow sufficient multiplication of this bacteria to cause death.
Increased permeability of the intestine wall to this toxin allows it to spread rapidly through the lamb; to the nervous system and brain. Death can occur in two hours or less, and rarely more than twelve hours after infection.
Where artificial rearing is practiced, a vaccination program against this group of bacteria is essential. All ewes should receive the initial primary course of vaccination before they lamb for the first time; two doses six weeks apart with the last injection at least two weeks before lambing. Ewes lambing once a year should receive a booster vaccination two weeks before they are due to start lambing. Ewes on accelerated programs need a booster injection two weeks before each lambing. If the ewe is fully vaccinated against the clostridial group of diseases before lambing, the colostral antibodies should protect the lamb for 10 - 12 weeks. As antibody levels can be affected by stress, it is essential that the environment, flock management and nutrition be maintained at the optimum for the pre-lambing ewe and the lambs. Artificially reared lambs can be vaccinated at 4 to 6 weeks of age. Lambs can receive a booster vaccination at 10 - 12 weeks of age.
In a system where prolific ewes have produced too many lambs for each lamb to receive enough milk, the extra lamb should be given supplemental milk or removed from its dam entirely. The preference is to foster, but this may be impossible. Typically, if a ewe has too many lambs a system must be developed to determine which lamb(s) is/are removed. The best rule of thumb is to remove the most different one, with size and gender (in order) being the determining factors. For example:
It is however advised for many individuals interested in generating replacement females to avoid removing the ewe lambs, as comparisons must then be made within the flock on lambs that have had unequal growth opportunities. By the same reasoning, a potential ram should also not be artificially reared.
There are a wide variety of techniques for feeding orphan lambs - varying from a nipple on a bottle for only a few lambs, to large, commercially available feeders. These measure and mix the milk replacer on a regular basis. The choice of system will depend on the number of lambs to be reared, individual circumstances and preferences. Regardless of which system is chosen, sanitation is critical.
For small numbers of lambs the most practical option is feeding a set amount of milk 2 or 3 times per day. Although labour intensive, this does allow for reduced cost of the milk feeding period and a fairly rapid transition to solid feed and easy early weaning. Either bottles fitted with nipples, or nipple pails can be used. What is important is that there is one nipple for each lamb, so that all have an equal opportunity to consume their allotted amount of milk.
Free Choice Feeding
Most systems designed to handle large numbers of lambs are based on lambs having access to milk at all times, so animals do not require individual attention. This is the best system with respect to minimizing labour. Various systems from nipple pails to teat bars to commercial units are available. Regardless of the system used for free choice feeding, each nipple can accommodate 4 to 5 lambs. The price of various systems is addressed in Table 1.
Nipple pails offer a low cost, easy to clean system. These can be purchased commercially or assembled by fitting the nipple-and-valve assemblies to the outer bottom portion of a bucket . The milk can easily be kept cold by floating a plastic (pop) bottle filled with frozen water in the milk replacer. The main disadvantage is the difficulty in protecting nipples from being chewed by the lambs. Damage to a nipple can result in the loss of all the milk replacer in the container.
One variation of the nipple pail is to have nipples attached to the pail by a length of hose, as in Figure 1. The nipples are accessible by the lambs inside the pen, while the container holding the milk is outside the pen. This allows the container to be kept below the level of the nipples (so if nipples are chewed, no milk is lost). To ensure all lambs drink from this system, it is important to have the hoses running from the pail to the nipple equipped with a simple non-return (or foot) valve. These types of valve units are available through automotive supply stores (for windshield washers). As with nipple pails, milk replacer can be kept cold by using frozen bottles of water.
Figure 1. Nipples can be attached to the container using a length of hose. Probably the most flexible, reliable and economical method of milk delivery to lambs in the pen. (Adapted from Publication 1507/E, courtesy of Agriculture and Agri-Food Canada).
Teat bars can be relatively easy and inexpensive to build, as they can be assembled from readily available plastic plumbing supplies. They consist of nipples attached to pipes or tubing through which milk replacer flows by gravity or is circulated by pump from a bulk supply. The milk replacer can be refrigerated, or left at room temperature. It is important that nipples used on a teat bar be designed or modified so they do not leak when filled with liquid. The publication "Artificial Rearing of Young Lambs" (Agriculture Canada, Publication 1507/E) has an excellent description of an inexpensive teat bar that was used at the Fredericton Research Station. It was made from 1.25 cm (1/2 inch) flexible plastic tubing fitted with standard 1.25 cm (1/2 inch) hard plastic 'T's inserted at 20 cm, or longer, intervals (any closer caused too much crowding). The part of the 'T' to which the nipple is attached was shortened to only one or two ridges so the hard plastic did not slide too far into the nipple. The far end of the tubing was left open so that pressure did not build up in the system and cause leaking at unused nipples when a lamb sucked another nipple. It was found that a minimum of 6 nipples per teat bar worked best to prevent leakage from unused nipples. Lamblux®* nipples were found to work successfully and are currently available to producers through stock supply outlets. Nipples were fitted into a board for feeding at an angle of about 65 degrees to approximate the angle of the ewe's udder and teats. If desired, a plastic shield can be fitted around the nipple to discourage or minimize chewing.
Automatic feeding units that measure and mix the milk powder with water and deliver the milk to the lamb pens are available commercially. To the authors' knowledge only one model, Lactec®, is currently commercially available in Ontario, and is distributed by Matelevage, St-Agapit, Quebec. They are an option when large numbers of lambs are being raised artificially, such as with dairy sheep operations or very prolific breeds on accelerated systems. The retail cost of the units has significantly dropped over the last five years.
Table 1. Advantages, disadvantages and associated costs of various feeding systems for artificial feeding/rearing of lambs.
Milk replacer is a complete and convenient way of delivering nutrients to the lamb. The instructions associated with the product have been developed to ensure animal health and growth. Each detail is the result of observations in the field and research. Precisely follow the instructions of the manufacturer with respect to mixing (temperature and procedure), feeding rates and sanitation. All of these factors are critical, and short-cuts may cause difficulties.
Mixing - ensure proper mixing, perhaps by using an electric appliance such as a hand blender. Lumps will contribute to abomasal bloat problems.
Feeding Rates - employ the feeding rates with respect to amount of powder per animal per feeding per day and powder to water ratios. Diluted replacer may contribute to gorging (especially in free choice situations), as the animals are trying to compensate for lack of nutrients. The more frequently small meals are fed, the better.
Sanitation - ensure feeding and mixing equipment is washed with sanitizing agents (e.g. dilute chlorine:water, 1:50), to prevent the proliferation of bloat and scour causing organisms.
Chilled Milk - any milk fed free choice should be chilled. Ice packs in the reservoir or keeping milk in a refrigerator may be solutions. Bottle fed lambs should be fed as per instructions with product.
Formalin - may be added to free choice milk (at 0.1% or 1.0 ml per 1 litre of mixed milk replacer) to prevent microbe growth, and to help restrict gorging (unpleasant flavour), especially if the milk is not chilled. Some lambs may reject the milk because of the formalin taste.
Robotic and Automated Feeders - Some units are designed in a way which makes following milk replacer guidelines impossible. The mixing may be incomplete, sanitation poor or free-choice milk is provided at warm temperatures. This will contribute to abomasal bloat when milk replacer is used. If these feeders are used, ensure the sanitation, mixing and feeding cycles do not conflict with the product used.
Cow's milk may be used in the feeding of lambs when available. One source might be from treated cows. Alternatively, milk from treated dairy goats or milk sheep may be used for these animals. One caution is that cow's and goat's milk are both lower in fat (energy). This may be compensated for by fortifying the milk with fats or oils which can be accomplished by adding 25-50 ml of corn, canola or coconut oil per litre of cow's or goat's milk (1 to 2 ounces per quart). Beef tallow, lard, shortening or butter could also be used, but may cause practical difficulties on account of their high melting point. Ensure that withdrawal times are adhered to for lambs fed milk that has been produced by treated animals.
The total daily feeding rate should be no more than 10% of a lamb's own body weight, and in as many as four feedings per day. Appropriate feeding frequencies at a given age are listed in Table 2. In instances where a range is given, the more frequent feedings may give a better result, but are not necessary.
Fresh water provided in bowls will make the animals more likely to utilize feed from troughs and bowls. Clean, fresh water must be available at all times from one or two days of age onward. At first, this water will be more of a novelty to the animals than actually utilized, but it will ingrain the behaviour of non-nipple feeding.
While lambs are being fed milk or milk replacer, it is imperative to begin providing solid feed. The more quickly lambs can be adapted to using grain or forage, the sooner milk products can be withdrawn successfully. The use of molasses containing feeds to stimulate intake or older animals to demonstrate trough feeding (mimicking behaviour) are useful tools in stimulating hard feed intake. This creep feed should be similar to the weaning ration in composition and analysis, in that it must be made of high quality ingredients, with 17 to 20% crude protein (CP). A coccidiostat may be included to control coccidial scours, and improve vigour and performance. Commercial creep feed is available, but it may also be prepared on-farm. A sample creep ration is given in Table 3.
* Percent of ration basis can be used to mix 100 lb. or kg batches (e.g. 35% Barley = 35 kg in 100 kg batch). Although oats are recommended to be included, barley may be substituted one for one to replace oats without altering ration analysis. Oat inclusion in the diet should be reduced if any hay is provided, on account of the high fibre content of oats and the possibility of causing 'hay bellies'. Corn may also be replaced by barley; this exchange will marginally increase CP levels, and marginally lower energy. Alternatively, corn may also be used in the place of part of the oats or barley in the ration; this will raise energy but lower CP levels of the diet.
** Fishmeal is an expensive protein, and is often not used as a result. The high levels indicated are to help provide a high quality protein to the lamb's system, with ease of digestion. Molasses will help mask odour.
a Supplemental vitamins and minerals should be included in the ration. If using a premix, use a lamb or sheep mineral (as opposed to beef, dairy) to avoid mineral metabolism complications, such as copper toxicity. Alternatively, trace mineralized salt ("TM 10") and Vitamin ADE mix (10,000 IU vitamin A activity-per-gram potency) may each be added at 50 grams per 100 kg feed.
b Therapeutic medications may be given to the lamb under a veterinarian's guidance using the feed.
* The information regarding teat bar nipples is included for the convenience of flock owners. Inclusion of this information is not an endorsement of the products by Livestock Technology.
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