Marie S. Bulgin, DVM, MBA, DACVM, University of Idaho
(Previously published in the Merck Manual – Veterinary Manual: June, 2016)
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types of sheep enterprises tend to use veterinary services the most. Smaller backyard producers may use veterinarians to perform procedures such as vaccinating, docking/tailing, castrating, and hoof trimming as well as to treat sick animals. However, larger producers in many countries often perform these routine procedures themselves, using veterinarians for such things as cesarean sections and help with disease control.
Wool production is usually a minor concern on the smaller production units; the number/pounds of lambs marketed per ewe joined/bred is the major determinant of economic return. The greatest potential loss is caused by neonatal lamb mortality, resulting from abortion, mismothering, starvation, and hypothermia. Second to that may be lack of growth weight due to internal and external parasites, protein deficiency, and lack of highly digestible and palatable feed for young lambs. Intensive management and good sanitation at lambing will reduce this loss. Labor-intensive lambing systems; intensive care of young lambs; and diagnosis, treatment, and occasional surgery of individual sheep may be justified by the value of the animals. However, preventive medicine programs are greatly needed in these management situations to prevent the numerous husbandry-related diseases associated with higher stocking rates. Attention to pastoral-related disease is important in the summer (i.e., internal parasite control) and in the winter for problems related to closer confinement, winter nutrition, and lambing problems.
In these types of production situations, record keeping becomes critically important for improvement. Animals must be individually identified so that the production of each can be monitored. Some countries/regions, such as the UK, European Union, Australia, Canada, and the USA mandate individual animal identification for disease tracking.
Lambs should be identified at birth, usually with a unique ear tag. The identification number, date of birth, dam, type of birth (single, twin, etc.), sex, and remarks such as “weak,” “required help birthing,” etc., are recorded. Recording birth weight is also desirable. Thus, scales, one appropriate for baby lambs and another to weigh market-size lambs, are an important tool to determine productivity.
Lambs should be weighed again at 50–60 days and 100–120 days, which indicates some measure of the milking ability of the ewe (60-day weight) and genetics of the lamb (120-day weight). Comparisons of the lambs’ rate of gain and twinning are two measures that can then be used to cull the ewe flock. It often is the thinnest ewe that turns out to be the best producer, and the fattest ewe the poorest. This is a relatively basic record keeping system in which other criteria can be assessed if desired.
In Australia, computer-based programs are used to compare animals within a flock as well as to compare flocks with other flocks on the plan. The USA sheep industry offers a similar plan (the National Sheep Improvement Plan), to which any producer can subscribe.
Feed and labor are always the largest annual expense for livestock producers, particularly for winter-fed or intensively fed sheep and lambs. Producers and their families usually provide the labor for smaller flocks, making feed the largest out-of-pocket cost. Therefore, nutritional management is of major importance. Veterinarians with knowledge of nutrition and mineral management can be extremely helpful, because feed imbalances can be costly.
Feedlot lamb feeding and management is also an area in which veterinary services can be very useful, providing least-cost rations and preventing major nutritional diseases such as acidosis, urolithiasis (see Urolithiasis in Horses), rectal prolapse, type D enterotoxemia (pulpy kidney disease, see Type D Enterotoxemia ), and polioencephalomalacia (see Polioencephalomalacia) and stress-related diseases such as pneumonia (see Lower Respiratory Tract:).