Profitability in sheep farming is largely dependant on the number of lambs weaned per ewe per year (aim should be at least two). High prolific breeds (e.g. Finn, Romanov) used in the breeding program can achieve and surpass this. Lamb survival is a result of good ewe management before and during lambing and attention to early care of lambs. Producers with flocks having a high percentage of multiple births should consider artificial rearing as a means to save and successfully rear more lambs and increase profitability. Under good management, orphan, mis•mothered, and multiple lambs can be successfully reared on milk replacer at an economic cost.
How to Prepare the Ewe for a Successful Lambing
The fittest lambs are born to ewes that have been maintained correctly from pre-mating to lambing. The ewe’s gestation period is from 144 to 151 days, with an average of 147 days. Weight gain is usual during pre-mating, followed by constant weight (condition score 2.5-3) between days 50-90 of pregnancy. Nutrition needs increase significantly in the last 4-6 weeks of pregnancy and is important to support rapid fetal growth (70% of growth occurs in last 6 weeks). Low birth-weight lambs tend to have a lower average daily gain than high birth-weight lambs (Greenwood et al, 1998). Also udder development for colostrum and milk production occurs at this time. If nutrition is incorrect, Pregnancy Toxemia (Twin Lamb Disease) can result. The ideal body condition score at lambing is 3-3.5. Ewes that are fat are prone to vaginal prolapse.
Ewe Management at Lambing
Provide lambing pens that are approximately 1.5 m² (1.8 square yards), with a corner divided off to give the lamb a safe area. Pens must have dry and clean bedding for each ewe. Each ewe can expect to spend 1-2 days in this pen. A ‘normal’ lambing has 3 stages: dilation of the cervix (approx. 4 hours); expulsion of lamb (up to 1 hour); expulsion of afterbirth (placenta) (2-3 hours after birth). Ensure that lambs start breathing. Clean mucus away from the nose and mouth. Disinfect the lamb’s navel to prevent infection. Encourage lamb to nurse as soon as possible to maximize absorption of Immunoglobulins from colostrum. Weak lambs may need to be tube fed. Observe lambs carefully to ensure they are feeding correctly and regularly and do not become chilled. This is especially important for multiple births.
Preparation for Lamb Survival
Hypothermia: The greatest proportion of lamb deaths is caused by hypothermia (a combination of chilling and starvation), which can account for the death of about 30% of lambs born alive. There are two critical periods: the first five hours of life (high heat loss) and 12 to 48 hours (inadequate heat production-starvation). Lambs rectal temperature should be 39-40oC (102-104ºF); however a hypothermic lamb will have a temperature from 20-35ºC (68-95ºF). Slowly warm up the lamb and feed colostrum or dextrose solution as soon as possible, consult a Veterinarian. Lambs at greatest risk from hypothermia include: small and premature lambs, lambs which are weak and/or limp at birth, lambs from ewes in poor condition, lambs from very old or very young ewes, lambs born into a cold, wet, or windy environment (chilling reduces the suckling drive), twins and especially triplets. Fat (energy) reserves in lambs are only 3% of body weight compared to 10-15% in adults. Lambs require adequate colostrum and brown fat (a type of fat lambs are born with) to help maintain heat levels. Brown fat reserves will be used within 3 days after birth. A weak lamb or a lamb not receiving sufficient milk will be at risk. Colostrum: Colostrum provides nutrients (high fat %) and immunoglobulins (Ig) which help prevent infection. Colostrum yield from ewes can be variable and low especially if the ewe has been underfed or is in poor condition. Ideally use own mother colostrum, then pooled ewe colostrum from same flock, then pooled ewe colostrum from another flock (same disease status), then cow colostrum (30% more via one extra feed), then artificial colostrum.
Rearing Lambs Successfully on Milk Replacer
There are many techniques for feeding milk replacer to orphan, mis-mothered or multiple birth lambs. The choice of system depends on number of lambs to be reared, individual preference, buildings, etc. Meticulous sanitation is critical for all systems. The correct disinfection of mixing and feeding equipment will help prevent the proliferation of bloat and scour-causing organisms.
Milk Replacer: Only high quality lamb milk replacer should be used that has been formulated to a high fat content more similar to ewe’s milk. Carefully selected ingredients ensure easy digestibility and solubility, thus increasing the absorption by the newborn lamb. Optimum vitamin and mineral levels will assist growth and promote health and immune function. Copper should not be added to avoid toxicity problems. It is important to follow the manufacturer instructions for mixing quantities and temperatures. Once mixed in suspension, milk can be cooled and stored at refrigerated temperatures for 24 hours before feeding. Under natural conditions a lamb will suckle the ewe up to 40 times each 24 hours. Small frequent feedings are more beneficial. Feed at manufacturers recommended rate according to average size of lamb. Milk consumption increases with the age and size of the lambs. Typically a bottle fed lamb should consume 10kg (22 lbs) of milk powder and 13-15 kg (29-33 lbs) under free-choice feeding.
Limit feeding: ideal for a small numbers of lambs. A quantity of milk is fed via a nipple on a bottle or nipple pail (one nipple per lamb) 3-4 times per day. It is labour intensive but can allow a reduced cost of the milk feeding period with an easier transition to solid feed and easier weaning. Milk should be fed at 38-40C (100-104ºF), body temperature.
Free Choice Feeding: Typical systems include nipple pail units, teat bars and commercial automatic feeders. Lambs have access to milk at all times and are group fed. The milk supply must not be allowed to run out as lambs will easily over feed with new milk. Milk should be fed warm or cool 4oC (39ºF) but not excessively cold. Typically, when milk is fed at 4oC (39ºF), it will be consumed in smaller amounts but more often. This reduces digestive upsets from overeating. In warm/hot weather, milk can be kept cold by floating a clean plastic (pop) bottle filled with frozen water in the milk replacer. Each nipple can accommodate 5-6 lambs and must be 40-45cm (16-18ins) above the stall floor. Lambs may require assistance in adapting to nipples for 1-2 days. Free choice feeding can minimize labour but increase the possibility of disease transfer. Lambs can easily chew nipples which can result in milk replacer loss from the container. Free choice feeding, results in a higher intake that encourages greater gains and so earlier weaning potential.
Lamb Pens: Lambs should be housed in a well-ventilated, draft-free shelter at temperatures of no less than 10 oC (50ºF). To improve livability and performance, lambs should ideally be raised in a room at 15-18oC. Lambs bedded on straw with solid floors require 0.55m2 (0.66 square yards) of floor space per lamb. Once established in a pen, lambs should not be moved and mixed with other lambs. It is best to feed lambs of the same age together. Teat bar systems with 4 teats can provide for a pen of 20 lambs. Commercial automatic feeders can feed 50-120 lambs per unit and so are ideal for dairy sheep operations or prolific breeds on accelerated systems. After about 10 days, larger groups can be formed and 10-25 lambs can feed off one nipple. Consult machine supplier for advice.
Feeding Lambs in Cold Conditions: Ensure lamb feeding equipment is protected from extreme environmental conditions to prevent large temperature variation and freezing of milk in pipes and containers. Provide lambs with adequate milk to maintain a positive energy balance and growth performance. Cold conditions can be a result of reduced air temperatures, higher humidity, wet bedding etc., or a combination of various factors. When lambs reach negative energy balance, immune status can be easily compromised and the lambs become susceptible to disease.
Milk Sheep: It can increase marketable milk and may also improve total milk lactation production, by feeding a quality milk replacer to lambs from milking ewes.
Weaning: Lambs are usually weaned from 21-45 days of age (average 30 days) and 12 kg bodyweight. Lambs should be consuming a minimum of 120-150 g (40-50 ounces) of creep ration per day for more than 2 consecutive days and have consumed a minimum of 10 kg of milk replacer.