Introduction
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. Among the Indian sheep breeds, the most important in number and distribution are Marwari and Deccani. The Marwari covers the greater part of the arid northwestern region, in both Rajasthan and
There has been a very great amount of inter-mixture among indigenous breeds. Crossing with exotic breeds has also been undertaken in order to upgrade the local breeds and to develop new ones, but no serious consideration has been given to genetic improvement. The current breeding policy for improving wool production for clothing and carpets and increasing mutton production in sheep is to cross the better carpet-wool breeds and extremely coarse and hairy breeds with exotic superior fine-wool and dual-purpose breeds. For improving carpet-wool production in some northwestern carpet-wool breeds and meat production in some south Indian non-woolly mutton breeds, however, selection within breeds is being recommended. These breeds were mostly based on exterior phenotypes: shape and length of ears, length and direction of horns, fleece type, body color, and tail length; there was little serious description of body weights, body measurements, population size, flock size and structure, management practices followed, productivity, and problems associated with their conservation and further development
Improving Milk Production
The milking ability of any breed can be improved with selective breeding and heavy culling, and that includes
Sheep dairymen can speed up genetic improvement by sharing top sheep from many regions, using group breeding, ram circles and artificial insemination. Group breeding, a system that involves several producers with the same goals forming a cooperative, is used by sheep industries in
In a ram circle, a group of dairy sheep breeders who live close together share each other’s rams during the breeding season, rotating them around. Artificial insemination is an easier means for speeding up genetic improvement, but can be expensive and is not always reliable, due to the anatomy of the ewe’s reproductive tract and the less-than-ideal quality of frozen ram semen.
Sheep Dairying Today
The Majors had always wanted to go into sheep farming, but low prices for wool and. The Majors increased their milk production significantly through selective breeding and now have a profitable product they sell to restaurants, specialty food shops, and mail-order and Internet sales as well as at their farm. Demand for “farmhouse” cheese led them to teach other
Purpose/Benefits
Lamb Production
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.
Milk Sheep
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.
Cautions
The single most important aspect of any rearing system is the proper administration of colostrums. Ideally, a lamb should receive 50 ml per kg (1 ounce per pound) of bodyweight of its own mother's colostrums, 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 system is functioning. If the ewe has too little colostrums, there are other options. These are (listed in order of preference):
- pooled ewe colostrums from the same flock
- pooled ewe colostrums from another flock (same disease status)
- pooled cow colostrums (use 30% more; feed every five hours to attain one additional feeding in the first 24 hour period)
- any combination of the above
- artificial colostrums
The longer the delay to utilize the colostrums, the poorer the animal's ability. Additionally, the quality of the colostrums secreted by the ewe rapidly drops towards normal milk production within hours of parturition. Colostrums administration/feeding at birth are 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 colostrums quality, and increases the likelihood of adequate quantities.
Choosing Lambs for Artificial Rearing
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:
- in a set of female triplets, if two are small and one is big: remove the largest one
- In a set of quadruplets, two are male and two are female, and one male is tiny: remove him. If the ewe is only capable of raising two: remove both males
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.
Feeding Systems for Artificially Reared Lambs
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.
Limit Feeding
For small numbers of lambs the most practical option is feeding a set amount of milk 2 or 3 times per day. Although labor 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 bottle 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 labor. 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.
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.
Feeding Rates
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 8 2. In instances where a range is given, the more frequent feedings may give a better result, but are not necessary.
| Table 2. Recommended feed source, and frequency of milk replacement (M.R.) feeding for lambs from birth to weaning. | ||
| Age (days) | Feed Source | M.R. Frequency |
| 0 -24 hr. | Colostrums | 4 to 5 times* |
| 1 - 3 | M.R. | 3 to 4 times daily |
| 4 - 7 | M.R. + creep | 2 to 3 times daily |
| 8-21 | M.R. + creep | 2 times daily |
| 21-35 | M.R. + creep | consider weaning |
Solid Feed - Creep 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 behavior) 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 or be prepared on-farm. A sample creep ration is given in Table8. 3.
Ingredient* 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 fiber 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 odor.
A Supplemental vitamins and minerals should be included in the ration. If using a premix, use a mineral from lamb or sheep (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.
FEEDING FOR SHEEP
The sheep NRC (1981) publication suggests that daily metabolizable energy (ME) costs for body weight (BW) maintenance in sheep are 93 kcal/kg BW0.75. However, it is known that the lactating animal has higher maintenance expenditure than her non-lactating counterpart because of larger guts and livers (Fell et al., 1972; Smith and
Table 8.4. Metabolizable energy (ME) and crude protein (CP) costs of lactation in the ewe. Each column should be summed to arrive at a total nutrient cost. Body weight (BW) is in kg, gain and loss are in kg/d, milk yield is in ml/d
| | ME cost (Mcal/d) | CP cost (g/d) |
| maintenance | 0.101 x BW0.75 | 4.456 x BW0.75 |
| activity (if grazing) | 0.15 x maintenance 0 lactation milk yield x (fat % x 9 + protein % x 5 + lactose % x 5)/64,000 | milk yield x protein %/56.1 |
| Body weight loss | 10.5 x BW loss | 446 x BW loss (max = 151) |
| body weight gain | 11.0 x BW gain | 446 x BW gain |
NRC (1981) has an estimate of 101.4 kcal/kg0.75 for lactating goats and Sutton and Alderman (2000) go even higher to 103.7 kcal/kg0.75. We selected 101 kcal/kg 0.75 as representative of the maintenance expenditures in a lactating dairy ewe (Table 1). Activity in the grazing animal will add 15% onto the estimated maintenance cost.
Metabolizable energy costs for lactation in goats are estimated as 1246.12 kcal/kg 4% fat corrected milk (NRC, 1981) and, for cows, as 1233 kcal/kg (NRC, 1989). A more universal approach is to consider fat and protein percentages individually because of the variation possible in either component. In Table 1, ME values of 9, 5 and 5 kcal/g were applied to milk fat, protein and lactose contents, respectively, and a 64% efficiency of ME incorporation into milk was assumed. A standard milk lactose percentage of 4.8 can be used if analyzed values are unavailable. Each kilogram of BW lost in support of lactation is assumed to spare 9.2 to 12.5 Mcal ME for the non-dairy ewe (NRC, 1985). This is a large range but it does not include the 8.2 Mcal ME/kg BW assumed for the dairy cow (NRC, 1989) or the 7.25 Mcal/kg for the dairy goat (NRC, 1981). Sutton and Alderman (2000) report a value of 10.5 Mcal ME/kg BW lost which is intermediate to the NRC (1985) sheep values so it was selected by us as most reasonable (Table 8.1). Gain of a kilogram of BW takes slightly more ME at 11.0 Mcal.Dietary crude protein (CP) requirements were calculated from metabolizable protein (MP) assuming a true digestibility of 85% and biological value of 66% (NRC, 1985). The daily maintenance MP requirement of lactating goats has been set at 2.5 g/kg BW0.75 (Sutton and Alderman, 2000) and 2.82 g/kg0.75 (NRC, 1981). Because of the tendency to overfeed protein, we selected the former estimate for our calculations (Table 1). Activity, such as walking during grazing, does not use up any additional dietary protein. Although NRC (1981) calculated the MP requirement for milk production as 51 g/kg 4% fat corrected milk, other publications use the milk protein yield as the starting point (Table 8 1), assuming efficiencies of conversion from absorbed protein of 66% (NRC, 1985), 68% (or 70% (NRC, 1989). Contrary to popular belief, feeding additional protein beyond what is calculated to be needed for nitrogen balance in the ewe does not result in greater yields of protein in milk. Milk protein production in the dairy cow is more related to dietary energy supply than dietary protein supply.
Each kilogram of BW gained or lost is expected to contain 256 g MP in cows (NRC, 1989) and 247 g MP in goat’s .We selected 250 g/kg as reasonable and include the restriction that a maximum of 85 g MP/d can be mobilized from body stores in early lactation.
Pasture Supplementation
To evaluate or formulate a feeding programmed for ewes, one must have some idea of how much dry matter (DM) is or will be consumed daily. This is very difficult when animals are grazing so extrapolations from stall-feeding observations are a main recourse. Reported a maximum DM intake of 5.7 % of BW at week 8 of lactation and typical values ranging from 3.6 to 4.2 %. Using daily Cr2O3 dosing and fecal collection for 10 d every month, we estimated forage intakes of 2.0 to 4.2 kg DM/d in ewes supplemented with 1.1 kg DM/d concentrate in the milking parlor. These intakes averaged 4.8 % of BW in total. Prediction of DM intake is often based on BW alone but more precise estimates also consider milk production, fat or energy content of the milk and stage of lactation (Holter et al., 1997). To our knowledge, no such equations exist for the grazing, lactating dairy ewe. A 70-kg ewe grazing pasture with a digestibility of 70% will consume approximately 4.5% of her BW in DM daily, which is 3.15 kg/d. To produce 4000 ml/d milk containing 6% fat and 5% protein, according to Table 8 1, she needs to consume 2.44 Mcal ME/d for maintenance functions, 0.37 for grazing activity and 6.44 for milk production. This is a total of 9.25 Mcal/d. Crude protein requirements are 108 g/d for maintenance plus 356 g/d for lactation, equaling 464 g/d in total. At 3.15 kg/d DM intake, 2.94 Mcal ME/kg DM and 14.7% CP are required. The pastures we observed on
Of 4000 ml milk/d.
Energy supplementation can be provided by whole grains. Protein supplementation should not be considered given the ease with which high-protein forage species can be cultivated and the selective consumption of high-protein plant parts by sheep. However, rumen-undegradable protein supplementation may be warranted because the proteins in fresh forages are highly degradable in the rumen and, if in excess, may not provide metabolizable protein to the ewe. Feedstuffs high in undegradable protein include fish meal, blood meal, corn gluten meal and roasted soybeans. Treacher (1989) documented 600 to 940 ml/d improvements in milk yield with fish and blood meal supplementation of forage-fed ewes.
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