633 - Sheep Flashcards
What is the biggest expenses on a farm?
Feed
What are some challenges associated with excellerated lambing systems?
Feed supply variations - you may have to supplement as you won’t always have the advantage of natural pasture
What are the main drivers of profitability? What are some things that reduce profitability on a sheep farm?
Stocking rate (production/Ha) - influenced by soil and therefore pasture quality
Weaning % - influenced by total lambs, disease, weather, genetics, nutrition
Other things that reduce profitability: drench resistance, lice, flies, Johne’s disease
What economic effect does drench resistance have?
> $2/weaner loss on returns from wool
$4/sheep if using an ineffective drenching product
At what points should vet visits happen ideally and what are we doing at these points?
Pre-joining - breeding soundness exams, nutrition, BCS
Post-joining - pregnancy diagnosis, scanning for empty/singles/twins to allow for cohorting and more appropriate feed management
Pre-lambing - BCS, nutrition management to prevent metabolic diseases, ensuring good quality milk in udders
Marking - vaccination, provision of pain relief
Weaning - data collection (especially weaning weight) to allow us to improve the next season
Why is is so important to increase feeding rate close to lambing?
2/3rds of foetal growth happens in the last trimester of pregnancy, we need to increase our feeding rates so that the ewes don’t lose condition while the foetus still gets fatter as this increases chance of dystocia
What is the target benchmark for abortive disease?
<2%
What is the target benchmark for perinatal mortality? Which complex contributes highly to this rate?
20-25% of lambs
SME complex = starvation, mismothering, exposure
What is the target benchmark for weaner death rate?
<4%
What is an acceptable lambing rate for merinos?
150-180%
What factors determine lambing rate?
Good quality rams
Joining ratio 1:50, but can get it higher
Good nutrition to ensure multiple ovulations - can also use drugs but you need to have good condition ewes
What are the nutritional requirements of ewes in their last pregnancy and how does it change when they are carrying singles vs twins vs triplets?
3.5-4% BW for ewes, 3-3.5% BW for goats
Singletons - requires nearly twice as much feed to prevent loss of body condition compared to non-pregnant ewes
Twins - requires 2.5 times as much than the non-pregnant ewe
Triplets - requires 3 times as much
What 4 major principles result in high productivity and efficient production?
- Maintaining ewe BW throughout year
- Growing young sheep at steady rate to reach adult BW at 19 months old
- Utilisation of superior genetics
- Remove non-productive sheep from flock
What is the target LW for most breeds of sheep?
55kg
What are the target weight gains expected from birth until weaning and then after weaning for slaughter lambs?
Birth to weaning - 280g/day
After weaning - 100g/day
What are the benefits of maintaining ewe bodyweight?
Steady foetal growth
Higher lamb survival
Higher milk production
High wool growth
Name 3 strategies that can be put into place when there is insufficient nutrients available from pasture.
- Alter stocking rate - sell or adjust stock or change priorities for different classes of stock
- Supplementary feeding - cereal grains, conserved pasture or forage crops during drought and periods of low pasture availability
- Accept the loss from underfeeding - not recommended
Discuss the 3 primary components of sheep production that have to be addressed in order to increase productivity.
- Lambing % - improve nutrition, use superior genetics, identify excessive losses
- Nutrition - assess pasture quantity and quality, supplementary feed as needed, leads to efficient weight gains in growing sheep and maintains ewes in a productive state throughout the year
- Animal Health Management - put programmes into place to ensure minimal morbidity and mortality
At what point do we cull/remove ewes from the flock?
If not pregnant at PD
If not rearing a lamb
If aged and no longer have sound mouths + udders
How do we measure performance?
Monthly pasture covers
Faecal egg counts + antiparasitic treatments
Wool production + hogget average daily wool growth
Meat production as kg/Ha and kg/kg ewe mated
Lambing %, proportion of pregnant ewes, proportion of ewes rearing lambs, proportion of twin lambs
Weaning %
Fertility index
Death rates at various stages
Financial data - cost of production, income, profitability (all per head and per hectare)
Explain to a farmer the best time for lambing.
We want lambing to happen ideally in July, August when the high rainfall coincides with strong pasture growth, so that by the time they are weaned in November there is a good supply of pasture and the farmer won’t have to spend too much (hopefully) on supplementary feeding ($$$$$).
A longer joining season pushes lambing back to happen at the time of maximal pasture growth, which means there will be more costs for supplementary feeding weaners for market as the farmer will have to buy in feed.
Explain the importance of correct feeding for ewes, especially for pregnant and lactating ewes.
Ewes need a massive amount of nutrients especially in their 3rd trimester to not lose condition as 2/3 of foetal growth is happening in this stage. If the plane of nutrition is only enough to support the foetus and the ewe is losing condition then there is not enough energy left over for production of good quality milk nutrition for the lamb which leads to high lamb mortality. If the lambs do survive they often have poor quality wool.
Correct feeding for ewes is also important to prevent them falling into negative energy balance and getting severely metabolically compromised - pregnancy toxaemia, hypocalcaemia, hypomagnesaemia, etc.
How can you differentiate between pregnancy toxaemia, hypocalcaemia, and hypomagnesaemia?
Pregnancy toxaemia - inc. BOHB levels; may also see dec. Ca and Mg; last month of pregnancy; slow onset of signs, only in pregnant ewes and does
Hypocalcaemia - total serum Ca lower than 2mmol/L; late pregnancy/early lactation; rapid onset of signs; pregnant + non-pregnant ewes/does
Hypomagnesaemia - total serum Mg lower than 0.5mg/dl (0.21mmol/L); early lactation/1-4 weeks post lambing; rapid onset of signs; pregnant + non-pregnant ewes/does
What are the clinical signs of pregnancy toxaemia?
Early Signs: separate from mob, low BCS, enlarged abdomen, appear blind, stop eating, wool break
Later Signs: drowsiness, nervous signs, recumbency, bruxism, coma + death in 3-4d, foetal death then apparent recovery then relapse
What are the 5Cs of mastitis management?
CONFORMATION - symmetrical udder with teats at 4 and 8 o’clock
CONDITION - BCS 3 or more reduces mastitis risk
CULL - ewes with chronic mastitis or old, thin ewes
CONSIDER SUPPLEMENTATION - to ensure they lactate well
COVER - cover exposed udders from wind and water
How can we induce parturition in a ewe? Why does it change depending on her stage of pregnancy and how is it different to inducing parturition in a doe?
Ewes: Before d55 you can use PG as the sole source of progesterone is the CL, during the second trimester the foetal-placental unit provides some progesterone so need to do PG + corticosteroids (dexamethasone), in the last trimester the foetal-placental unit is the sole source of progesterone so only need corticosteroids to terminate/induce.
Does: PG at any stage as they rely on the functional CL for progesterone the entire gestation length.
Describe the importance of pregnancy diagnosis in a sheep enterprise.
Allows for cohorting of ewes (even if just pregnant vs empty) so that they can be appropriately fed. Non-pregnant ewes can then be sent to market, which can add money back into the farm. Pregnant ewes can be fed appropriately which lowers the chance of metabolic disease and other complications.
How long is the ideal joining period for sheep? Explain.
5 weeks
65% of sheep will fall pregnant after a single mating cycle, reaching 85% pregnancy rate with 2 cycles, of about 34d or just under 5 weeks.
The benefit of having the ram in for another cycle and extending the joining period is minimal as the ewes that haven’t gotten pregnant in the first 2 cycles have poorer fertility and is not enough to outweigh the added costs of having a later and extended lambing period.
The other benefit of having a shorter joining period is that the lambing period will be condensed and have reduced costs of extra labour during that time.
What are some consequences of under or over feeding ewes during pregnancy?
Dystocia, poorer quality wool from offspring, poorer average daily gain of offspring, lowered perinatal survival, metabolic diseases (pregnancy toxaemia for example).
Discuss the appropriate nutritional management of ewes carrying twins or triplets (multiples) in the last week of pregnancy.
What feeds should be avoided in late pregnant ewes and why?
High energy supplementation (barley) during the last week to boost colostrum production, feed whole barley grain @1% LW in addition to what they normally get, making sure to gradually introduce it to avoid acidosis.
Avoid clover, lupins + lucerne as they often contain oestrogenic compounds so can lead to a higher chance of abortion in late pregnant ewes.
Maize with mould also has oestrogenic compounds, and maize can be calcium binding which predisposes to hypocalcaemia.
When would abortions warrant further investigation? How would you go about investigating abortion in small ruminants?
When to investigate - abortion levels greater than 5%, abortions occurring over a short period of time, abortions occuring in the same locations.
Get a history and physical exam
Take samples - put 1/2 on ice for virus isolation, PCR + bacterial culture, and the other half in 10% buffered formalin for histology.
Samples of - foetal stomach contents, liver, lungs, brain, placenta (including placentoma), blood for serology (paired at time of abortion and then another in 2 weeks or so to allow for titre comparison).
Explain the pathogenesis of pregnancy toxaemia/ketosis/twin lamb disease.
Ineffective gluconeogenesis leads to increased glucose demand from foetuses –> hypoglycaemia –> lipid metabolism –> inc. ketone bodies/cortisol –> hyperketonaemia + hyperketonuria
Describe the signalments associated with hypocalcaemia.
Ewes in last month of pregnancy + early lactation
Young sheep grazing green oats/young grasses low in Ca
Sheep fed cereal grain only diets
Stress/fasting, shearing, crutching, transport
Older animals - have dec. mobilisation of Ca
Sheep fed on oxalate containing plants or given long courses of tetracyclines - both bind Ca
Describe the signalments associated with hypomagnesaemia.
Animals on lush green young rapid growing pasture
Pastures fertilised with nitrogen and potassium
Young cereal pastures
Late gestation/early lactation ewes + does
Stress + temporary food deprivation
When should you intervene in a lambing?
If the ewe has been having active stage 2 contractions (abdominal tenesmus) for more than 30 mins
Total period of lambing exceeding 90 mins
If the lamb/s have any of the following presentations: head but no legs, legs but no head, tail no legs, 1 front leg and 1 hind leg
How can we prepare ewes for weaning to prevent mastitis?
Cut grain feeding 3-5d before weaning to reduce milk production
Replace grain with grass hay
Withhold water and food for 12h before weaning
The more flaccid and empty the udder is the less likely it is for microbes to enter and cause problems
What is the normal temperature, HR, RR, and weight for newborn lambs/goat kids?
Temp - 38.6-39.9 degrees C
HR - 80-100bpm
RR - 36-48bpm
Weight - 3-4kg for kids, >4kg for lambs depending on the number born/ewe
What are some management strategies we can implement to decrease the risk of congenital disease outbreaks?
Not using live vaccinations in the first trimester
Avoid teratogens including joining ewes on alkaloid/bitter lupins
Not breeding defective sheep
Cull lambs with defects
List 4 congenital diseases of lambs/kids.
- Entropion
- Cerebellar atrophy/Daft Lamb Disease
- Congenital goitre (iodine deficiency)
- Congenital selenium deficiency
- Congenital copper deficiency
- Border Disease
What is entropion? What are the clinical signs?
Rolling in of the eyelids (usually the bottom/lower eyelid) leading to blepharospasm, epiphora, matting of wool around the eyes, corneal opacity, blindness, lowered growth rates
How can we treat and prevent entropion?
Manual eversion for less severe cases - often recurrs
Surgical staples for more severe cases
Inject 2ml sterile saline or air or benzathine penicillin or oxytetracycline SC into affected lid
Surgery
Prevent - cull rams whose progeny have entropion, do not breed affected sheep
How do we manage cereballr atrophy in lambs in a commercial setting?
Euthanasia
A farmer comes to you because he has had several Angora goat kids born with swellings posterior to the larynx which died within their first week of life. The does have been kept on pastures used to grow sorghum and brassica. What is your likely diagnosis and how are you treating it?
DDx - Congenital goitre (iodine deficiency)
Cx - enlargement of thyroid glands, death of neonatal kids/lambs
Tx - potassium iodide PO
Border disease is similar to which disease of cows?
BVDV
