Summary of paper prepared by Justin Hurst BVSc, Veterinarian, Nufarm Ltd
What animal health variables influence the profit from your ewe flock?
70% of all lamb deaths can be avoided by good ewe and lamb nutrition and preventive measures. Each ewe lost between mating and lambing is equivalent to two ewes wintered and over two lambs tailed.
Important animal health management points:
Important times and classes of stock for supplementation are:
Cobalt (Vitamin B12)
Toxoplasmosis is a protozoan infection leading to embryonic loss, abortion, or birth of weak or dead lambs, in immune naive sheep. Infection through ingestion of cysts in the faeces of young or immunosuppressed cats.
Low levels of infection are common (less than 5%), but epidemics can occur in naive flocks with dry/dry rates over 20%. Barren young ewes generally show no other clinical effects but wasting of older ewes has been noted.
Management via live toxoplasma vaccine given once at least four weeks prior to tupping, as well as avoiding feeding supplements contaminated by cats.
Infection with Campylobacter fetus in the last trimester of pregnancy can cause abortion or lamb death soon after birth. The bacterium are very contagious and spread via contamination of pasture by aborted material or ewe discharges. Management by vaccination (primary and booster vaccinations), and through reducing stock density and isolation of infected animals.Back to the top
Occur in late pregnancy - caused by faults or changes in the nutritional management of the flock. Can be confused with superphosphate poisoning. Treatment by injection of calcium borogluconate, and oral energy solutions (propylene glycol) with Vitamin B12 and Iodine for sleepy sickness. Must be given early.Back to the top
Effect ewe profitability through reduction in fertility at mating - liver damage ( Facial Eczema) may effect lifetime performance. Diagnosis difficult, management based on avoidance of known susceptible pastures and genetic resistance.Back to the top
Gastrointestinal parasites are potentially the most significant production limiting disease in sheep. Includes reduced feed intake, reduced wool and milk production, as well as increased bodyweight loss and reduced lamb weight at birth.
Profitable ewe farming requires Parasite Management, not just Worm Control. Why?
Two recent changes in our thinking involve the effect of different stock classes on pasture contamination, and our ability to determine if pasture is "safe".
Young stock will always have higher FEC's - ewe flock contributes up to half the total egg output on a farm, due to their higher faecal output.
Sources of parasite egg contamination of pastures.
Controlled release and persistent action anthelmintics has allowed management of the direct cost of internal parasites to the ewe as well as having an affect on lamb survivability and production. With the prolonged action ofCRC many or all of the benefits of parasite management around parturition can be obtained. Potential benefits for lactation in high fecundity ewes, leading to significant increases in lamb weight weaned per lactating ewe.
Prolonged action anthelmintics may be indicated around lambing where ewe bodyweight/condition less than optimal.
Timing of the peri parturient rise in faecal egg output, (or reduction in ewe immunity) is variable between years and age classes. High FECs may occur throughout winter, particularly in young stock. Preventing the effect of parasitism pre lambing has been shown to be able to influence lamb birthweight and survivability, hence ncreasing kilograms of lambs weaned per hectare.
Effect of time of albendazole CRC treatment of Merino ewes on lamb survival
(adapted from Mulvaney 1997)
|No. days prelambing of treatment
|Lamb survival %
To determine if intestinal parasites are limiting ewe production the following factors should be considered:
Anthelmintic use as a one off event should include nutrition, body condition, trace mineral status, and stocking rate as well as Faecal Egg Count data. Long term productivity benefits or costs (resistance and immunity development) need to be considered and traded off against current financial considerations and farm goals.Back to the top
Animal health must be preventative and needed to give excellent returns on investment. Through careful planning and monitoring, including selection of time and classes of stock to be treated and use of whatever "safe" pasture that can be created, major benefits of parasite management can be achieved with minimal effect on farm worm resistance status.Back to the top