PATHOLOGY - Lamb Ill Thrift Flashcards
What is ill thrift?
Ill thrift is the failure to maintain condition and bodyweight or failure to grow as expected
What are the three main lambing systems in the UK?
Spring lambing flocks
Early lambing flocks
Store lambs
Describe briefly the timeline for a spring lambing flock
Spring lambing flocks lamb in the spring and thus lambs tend to be put out to pasture with their mothers within a few days of life. The lambs are then usually finished and sold in the autumn when the price will be the lowest (as there will be the most plentiful lambs at this point in the year)
Describe briefly the timeline for early lambing flocks
Early lambing flocks lamb in December/January and thus lambs tend to be kept inside until weather and pasture conditions improve. The lambs are then usually finished and sold in the spring when the price will be the highest
What are store lambs?
Store lambs are lambs bought in the autumn to be finished and sold
Why is efficient lamb growth so important?
Efficient lamb growth is so important as the longer lambs are on the farm, the more resoruces they will use, however if they are finished and sold at an optimal time there will be more resources left for the ewes to help prepare them for the next lambing season (such as grass, feed, decreased housing pressure etc). Furthermore, the earlier lambs are sold, the higher price they will be sold for at market and the better growth rates they have the better the meat quality will be at slaughter
What is the target daily live weight gain for lambs pre-weaning?
300g/day
What is the target daily live weight gain for lambs post-weaning?
200g/day
What are the benefits of regularly weight lambs?
Regularly weighing lambs allows for the monitoring of growth and daily liveweight gain, and weighing at specific points in their development can help to identify potential factors involved in altering growth rates and thus help to make more informed management decisions
At which points should lambs ideally be weighed?
Birthweight
8 weeks old
Weaning
Fortnightly post-weaning
What is the target birthweight for lambs?
4.5 - 6.5kg
Which main factors can influence lamb birthweight?
Ewe nutrition during late gestation
Genetics
What is the target weight for lambs at 8 weeks old?
20kg
Which main factors can influence lamb weight at 8 weeks old?
Ewe nutrition during late gestation and lactation
Ewe lactation performance
Ewe mothering performance
Ewe disease status
Ewe management
Why is ewe nutritional status so important to lamb growth rates pre-weaning?
Ewe nutritional status has a direct effect on the birthweight and vitality of the lambs as well as the quality and quantity of the colostrum and milk produced which is the most energy dense feed a lamb will receive. Thus, grass and pasture management, as well as maintaining BCS with adequate nutrition is essential for for ewe nutrition and milk production
What is the target weight for lambs at weaning?
Minimum weight of 16kg but ideally over 25kg
At what age are lambs weaned?
Lambs are typically weaned at 12 weeks old
(T/F) There is expected to be a drop in weight at weaning in lambs
TRUE. There is expected to be a drop in weight and daily liveweight gains at weaning as lambs are no longer reliant on energy dense milk, however this decline should be temporary
What is indicated by a persistent decrease in weight and daily liveweight gains in lambs at weaning?
A persistent decline in weight and daily liveweight gains in lambs at weaning indicates they were weaned too early
What is indicated by a large increase in weight and daily liveweight gains in lambs at weaning?
A large increase in weight and daily liveweight gains in lambs at weaning can indicate weaning was done too late, and the lambs had started to compete with the ewes for nutritional resources
When would delaying weaning be appropriate?
Delaying weaning would be appropriate if there is plenty of good quality grass available for both the lambs and ewes so they don’t have to compete for nutritional resources
When would early weaning be appropriate?
Early weaning would be appropriate if there is limited grass available fo the ewes and lambs to prevent competition for nutritional resources, as the lambs will be overcompeted by the ewes are their growth rates will decline
What are the main influences on lamb weight post weaning?
Lamb nutrition
Disease status
What is the daily dry matter (DM) intake for lambs?
2.5 - 3.5% of their bodyweight
What can lambs consume to reach their target dry matter intake?
Milk
Grass
Forage crops
Concentrates
Be aware that lambs will become less reliant on milk and thus the other factors are very important
What are the potential causes of nutritional deficits and consequently poor nutrition in lambs?
Poor milk yield and quality
Poor ewe management
Poor quality pasture
Inadequate grass length
Unpalatable feed
Inadequate feed face space
Inadequate lying space to ruminate
Lack of fresh, clean water that is readily available and easy access
What is the optimal pasture length for lambs?
5 - 8cm
Which techniques can be used to optimise pasture quality?
Rotational grazing and maintenance of clover can be used to optimise pasture quality and consequently lamb nutrition as this allows the pasture adequate time to recover from grazing allow for a high proportion of nutritious plants on pasture
What are the main causes of ill thrift in pre-weaning lambs?
Nutritional deficits
Parasitic gastroenteritis (PGE)
Nematodirosis
Coccidiosis
Lameness
Prolonged effects of neonatal disease
Which two disease arise in lambs in the spring?
Nematodirosis and coccidiosis both arise in the spring and cause very similar clinical signs, furthermore these parasites can cause co-infection resulting in more severe clinical signs than either diseases on their own
Describe briefly the epidemiology of coccidiosis in sheep and lambs
Adult sheep cycle and shed low numbers of Eimeria oocysts, contaminating the environment. Eimeria is always present within a flock however the adults have developed immunity and thus clinical disease is only seen in naive animals. Naive lambs early in the lambing season will ingest the oocysts shed by the adults and augment the contamination through shedding larger quantities of oocysts into the environment. However, these lambs are generally not exposed to a high enough infection pressure to develop clinical disease, so they develop immunity without showing clinical signs. However, lambs born later in the lambing season will be exposed to higher infection pressures and thus are more likely to develop clinical disease. This usually occurs when these lambs reach 3 weeks old due to the prepatent period of eimeria, although clinical disease can be seen in lambs sold and moved to a new farm (i.e. store lambs) where they can be exposed to a new species of Eimeria and develop clinical disease as the acquired immunity is species specific
What is the pre-patent period (PPP) for eimeria?
3 weeks
What are the risk factors for coccidiosis?
Lambs born late in the season
Lambs 3 to 8 weeks old
Lambs moved to a new farm
Poor hygiene (specifcally wet, faeces accumulated areas)
Short grass
Why is poor hygiene a risk factor for coccidiosis in lambs?
Oocysts survive well in wet, cool conditions where faeces has accumulated
Why is short grass a risk factor for coccidiosis in lambs?
Short grass causes lambs to graze closer to the ground where eimeria oocysts accumulate
What are the clinical signs of acute coccidiosis in lambs?
Dark, mucoid diarrhoea ± blood
Dehydration (this is what kills the lambs)
Abdominal pain
Anorexia
Ill thrift/weight loss
Depression
What are the clinical signs of chronic coccidiosis in lambs?
Chronic ill thrift and poor growth rates
What causes chronic coccidiosis?
Chronic coccidiosis is caused by long term damage to the intestines due to eimeria infection
How do you diagnose coccidiosis in lambs?
History (grazing, management etc.)
Clinical signs
Faecal oocyst counts
Response to treatment
Post mortem
Why are faecal oocyst counts so challenging to interpret in lambs?
Faecal oocyst counts are very challenging to interpret in lambs as there are many species of Eimeria that can infect lambs however only a small proportion of these species are pathogenic, and you have to have a very high oocyst count in combination with appropriate history and clinical signs to have a suspective clinical diagnosis
What is required for definitive diagnosis of coccidiosis?
Speciation to determine if the Eimeria is pathogenic
What are the limitations of speciation to diagnose coccidiosis in lambs?
It takes several days to get speciation results back and by that points lambs will have started to die, so you have to treat based on a suspective diagnosis however the speciation results can be used to help guide future prevention
What are key post mortem (PM) features that can be used to diagnosis coccidiosis in lambs?
Merozoites in smears from intestines of freshly dead animals
Histopathology of intestines from freshly dead animals
Have to collect sample within 20 mins of death due to rapid autolysis of the intestinal mucosa
How can you treat acute coccidiosis?
Fluid therapy (usually oral unless high value lamb)
Anti-inflammatory drugs
Remove lambs from source of infection
Anticoccidial drugs
What are the anticoccidial drugs licensed for sheep in the UK?
Toltrazuril
Diclazuril
What is the main difference betwen toltrazural from diclazuril?
Toltrazuril treats all stages of eimeria infection so only has to be administered once, however diclazuril only treats the later stages of disease to needs to be repeated 2 weeks after initial adminstration
Why are sulphonamides not a recommended treatment for coccidiosis?
Some vets use sulphonamides in the treatment of coccidiosis in lambs, however sulphonamides are coccidiostatic and thus eimeria will resume their lifecycle as soon as treatment is ceased and clinical disease will arise
How can you prevent coccidiosis in lambs?
Muck out sheds regularly
Avoid dampness in sheds
Rotational grazing
Keep lambs born later in the lambing season in different sheds/pasture
Seperate age groupsn
Decrease stocking densiry
Maintain optimal pasture height
Preventative anticoccidial drugs
What is decoquinate?
Decoquinate is a coccidiostatic drug which can be put into the ewes feed prior to and after parturition to decreased environmental contamination and thus exposure of naive lambs to oocysts. Decoquinate can also be used to treat lambs however it has to be used for 28 days due to being coccidiostatic to prevent the eimeria lifecycle from resuming
When are preventative coccidiocidal drugs appropriate?
Coccidiocidal drugs (such as toltrazural and diclazuril) can be used preventatively in lambs that have been moved to a high risk area for coccidia. Administer these drugs pre-emtively 2 weeks after the lambs have been moved
What is one of the main limitations of preventative anticoccidial drugs?
Preventative anticoccidial drugs may prevent lambs from developing an immune response
What are the main causes of ill thrft in post-weaning lambs?
Nutritional deficits
Mineral deficiences
Parasitic gastroenteritis (PGE)
Liver fluke
Lameness
Prolonged effects of neonatal disease
Which mineral deficiencies have the most profound effect on growth rates in post-weaning lambs?
Cobalt deficiency
Selenium deficiency
What is the function of cobalt?
Cobalt is required by ruminal microbes to synthesise vitamin B12 which is essential for metabolism
What are the risk factors for cobalt deficiency in sheep?
Soil type
Geographical location
Dry weather
Fast growing pasture
Low amount of clover on pasture
What are the clinical signs of cobalt deficiency in pregnant ewes?
High perinatal lamb mortality
Reduced milk yield
What are the clinical signs of cobalt deficiency in lambs?
Watery ocular discharge
Unkempt fleece
Anaemia
Diarrhoea
Anorexia
Poor growth rates/ill thrift
Hollow sublumbar fossa
Hepatic encephalopathy (due to ovine white liver disease)
How can you treat cobalt deficiency?
Injectable vitamin B12 to promote appetite followed by other methods of supplementation such as repeated injectable vitamin B12 or oral supplementation if the pasture is cobalt deficient
What are the clinical signs of selenium deficiency in lambs?
Poor growth rates/ill thrift
Impaired immunity
What are the clinical signs of selenium deficiency in adults sheep?
Reduced fertility
Weak lambs born
White muscle disease
How can you treat selenium deficiency?
Injectable selenium
Oral supplementation
Be careful as overdosing selenium can be toxic
How do you diagnose mineral deficiencies in post-weaning lambs?
History (grazing, weather etc.)
Clinical signs
Soil/pasture testing
Serum mineral levels
Liver biopsy (as these minerals are stored in the liver, indicates more long term deficiencies)
Post mortem
How does liver fluke affect lamb growth rates?
Liver fluke in ewes can cause poor ewe BCS which will result in low lamb birthweight and poor colostrum and milk production which will consequently affect lamb growth rates. Liver fluke in post-weaning lambs can cause direct ill thrift and poor growth rates
How does lameness affect lamb growth rates?
Lameness in ewes can cause poor ewe BCS which will result in low lamb birthweight and poor colostrum and milk production which will consequently affect lamb growth rates. Lameness in pre-weaning and post-weaning lambs can cause direct ill thrift and poor growth rates
