Sheep Flashcards
What factors affect the choice of type of sheep enterprise? Eg. Breeding, wool, meat.
Potential profit
Personal preference
Location/climate/feed supply/market access
Capital to buy stock/exposure to high prices
Attitude to risk - disease, ability to de stock, etc.
Control of genetics
Facilities - fencing, shearing shed
Availability of labour
What is the average shearing rate?
$7 per head
How long do you generally keep ewes?
Keep for 5-6 years
Good ewes can remain productive for up to 10 years.
How is wool sold?
$/ha = quantity x quality
Marketed mainly via wool brokers
In the future, expect move towards electronic auction which will greatly decrease marketing costs.
What are the most important factors to determining value of wool?
Micron, strength, vegetable matter, length, staple, marketing factors, mid breaks, colour and style.
Describe how wool micron drives price.
The smaller the micron (diameter) the higher the price.
This price has increased over the last 10years.
Define what a ‘lamb’ is.
Up to 12 months old, hasn’t yet cut 2 teeth.
How is lamb marketed?
Can be through saleyards (stock agents-paid for weight and fat).
Over the hook - abbotoir
Contract - weight and fat price grid with agreed delivery date. Discounts if don’t meet terms, paid for weight, not per head.
Private/paddock sales
Electronic
What is carcass weight in sheep generally estimated to be about?
CW - slightly less than 50% live weight.
Describe the requirements of lambs for different markets.
Domestic - 17-22kg CW, 6-15mm GR (12th rib), fat score 2-3, first or second cross lambs.
Supermarket - 18-22kg, GR 7-12mm, fat score 2-3, second cross preferred.
Food service - 20-25kg, GR 7-15mm, fat score 2-3.
Heavy export - 20-30kg, GR 6-20mm, fat score 2-4
Light export - 10-14kg, up to 10mm fat (very low).
When is the lamb price usually at a premium?
In winter because numbers are lower.
Currently about $6/kg currently.
What are the main profit drivers in sheep systems?
Quantity sold/ha x $ value (stocking rate and weaning % important).
Cost of production (efficiency) - match feed supply to demand (cheapest feed is pasture), labour efficiency, enterprise scale (spread overhead costs).
What differences are there between the top 20% of the industry and the remainder?
Top 20% have higher stocking rates therefore higher lamb marking %.
As a result they have a higher GM$/ha/100mm of rain.
True or false, low producers cost as much to run but produce less, therefore they lead to decreased income and increased cost of production.
True
How do we get the right sheep for our herd?
Selection - aim to improve flock
What should breeding objectives consider?
Direction of the enterprise
Aim to improve profitability - increase output, decrease input.
Consider all components and their associated economic weights.
Define repeatability.
Extent to which superiority in one year is maintained in the next.
Ex. Phenotypic variation in fleeces weight.
What does GFW stand for?
Greasy fleece weight.
What does h2 stand for?
Heritability
What is selection differential?
The difference in fleece weight between selected individuals and the whole flock.
How do you determine EBV’s using an equation?
EBV = heritability x predicted superiority
Have to make if specific for a specific trait, eg. Greasy fleece weight.
What is genetic correlation?
The extent to which two traits are controlled by the same set of genes.
To what extent will selection of individuals of high performance for trait 1, give rise to progeny of high performance for trait 2.
How do you determine selection index?
EBV x REV for GFW, FD and BW all added together.
Gives overall genetic merit in $.
Describe the breeding structure of the merino industry.
Pyramid with parent studs at top (small number with big influence on genetics), then daughter studs(only buy from parent studs), general studs (buy from only one or multiple daughter studs) and commercial studs at the base.
Has a massive influence on how the genetics are passed onto the wider industry.
How do you make genetic progress?
Objective - know what traits to select for.
Know which traits have adequate heritability - fertility is desirable but has low heritability.
Use effective selection tools - ASBVs if available.
Use selection pressure on desired traits.
Briefly describe the open nucleus format used within the Australia Merino Society.
Central nucleus which produces Rams available to all members of a cooperative.
Not widely used.
Describe the effect of selection on Australia’s sheep industry.
Allows for selection differential - superiority of selected animals over average.
Heritability - degree to which superiority transferred to the next generation.
Response due to selection = h2 x (selection diff./2)
What are the three most important factors to consider when deciding where to go with your breeding objectives?
Trait measurement - which traits, which animals, males or females, progeny test.
Estimation of breeding value - phenotypes, pedigree, BLUP, genetic markers.
Reproductive technology - artificial insemination, multiple ovulation/embryo transfer.
What is generation interval?
Average parent age when offspring are born.
Longer generation interval means slower response to selection at the same stocking density.
Different for Rams and ewes.
Smaller generation interval has faster progress however less superior animals are selected.
Merinos; Rams 1-2 matings, ewes 4-5 matings.
Describe a sheep enterprises genetic improvement options.
Remain with current stud, change ram source or change ram and purchase ewes.
Ram source has a large impact, merino flocks are typically bred on a bloodline.
What ever stud is chosen then your genetics will follow that studs breeding objectives.
Changing the ram and purchasing ewes allows rapid progress but is costly.
How can you identify better studs/individuals when changing your ram source?
Do bloodline comparisons - wether trials. Look at the stud breeding objectives. Sire evaluation On farm trials Merino select.
What do bloodline trials do?
Aim to compare performance in the same environment/management.
Eg. Fibre diameter, fleece weight and $GM/DSE
What factors shod you consider when choosing a bloodline?
Define your breeding objective
Benchmark current bloodline performance
Consider all traits
Where are the possible bloodlines heading?
Constraints - price, availability, distance, available information
What is a central test sire evaluation? Discuss this.
CTSE is the breeding performance of individual sires measured by evaluating progeny.
A sires progeny performance is expressed relative to other sires.
Various test sites across Australia - each has annual mating of 10-16 sires. Each side mated to about 50 ewes that are representative of the strain - produce at least 25 progeny.
One link sire is mated for each 7 sires at a site - act as genetic connections between years and sites.
Progeny performance is assessed at 10-16 months (1st) and 17-24 months (2nd); includes fleece testing and visual by sheep classers.
What is sheep genetics Australia? What is their mission and how are they going to achieve it?
Mission - genetic improvement for a sustainable and profitable Australian sheep industry facilitated by the worlds best sheep genetic evaluation system.
Achieve this through common language (ASBVs), regularly updated and accessible information, range of commercial traits for different ages, accuracy and across-flock linkage, fair pricing, QA standards, breeders have ownership and disclosure of data.
>80% of meat sheep breeds evaluated, >50% of merinos evaluated.
What are ASBVs?
Standardised breeding values.
Minimum of 47, based around 0.
Accuracy values.
If the data doesn’t meet quality assurance and accuracy then it is reported as flock breeding values (FBVs).
Need to compare ASBVs to the current average.
Negative is not always bad.
What is an index?
Combines the ASBVs for several traits into one value.
Can be available to suit a range of different breeding programs.
Allows a quick selection guide to narrow down which Rams to look at.
What is micron premium?
Indicator of economic advantage of reducing fibre diameter.
Strong relationship between micron and price-the finer the wool, the higher the price. As micron increases, the fibre diameter decreases.
Higher premiums have more emphasis on diameter.
Low premiums have more emphasis on fleece weight.
What are some of lamb plans terminal indices?
Carcase plus - wwt (weaning weight), pwt (positive weaning weight-most emphasis), fat and emd (eye muscle depth). Designed for high growth and muscle depth with leanness.
Trade $ index - pwt, fat, emd. Target 19kg Carcase.
Export $ index - pwt, fat, emd. Target 26kg Carcase.
Lamb 2020 index - bwt, wwt, pwt, fat, emd, wec. 22kg Carcase lamb bred from merino or first x ewe.
What are lamb plans maternal indices?
Maternal $ index (MAT$)
Dual purpose $ index (DP$)
Self replacing Carcase $ index (SRC$)
What is the maternal $ index aimed at?
Aimed at maternal breeds in place of the breed specific indexes.
Balances the key economic traits relevant to most maternal breeds.
What is the dual purpose $ index aimed at?
Aimed at self replacing maternal flocks with additional focus on wool quality.
Has the same breeding objectives as maternal $ index, with additional moderate emphasis on improving greasy fleece weight and a small emphasis on reducing micron.
What are the aims of self replacing Carcase $ index?
Used by breeds included in the terminal analysis with the intention of producing a self replacing flock with a strong emphasis on Carcase traits.
Has the same breeding objectives as the maternal $ index except that removal of economic values for fleece traits. This removal of selection pressure for fleece traits allows higher gains to be made for growth and Carcase traits.
What is the purpose of selection demonstration flocks?
Aimed to evaluate and demonstrate the strengths and weaknesses of merino selection methods.
Methods are based on the use of sheep classers, skin based selection, objective measurement systems and tools.
Discuss practical sheep selection.
Measured information on important traits from raw or ASBVs.
Visual inspection for faults and non measured traits.
Emphasis depends on your breeding objective, cost, ram/ewe ratio (selection pressure).
Discuss the selection of flock ewes.
Usually select before first joining - close to 18 months.
Number of replacements depends on number being culled.
Visual measurement
Prerequisites - >15 months, >4 months wool (shorn once), same age and history.
Overall quality.
Class to your breeding objective
Older ewes culled annually on health (udder, teeth, condition).
Discuss the selection of flock Rams.
How many are needed?
Choose them from a stud that matches your breeding objective.
Overall impression
Rank/class into tops and seconds based on measurements/index and visual.
Draft tops and seconds off and inspect.
Ram auction sales - competitive, value for $
What does the number of lambs sold per ewe result from?
Ewes mating, ewes conceiving, level of embryo mortality, ewes pregnant, ewes with multiple foetuses, lamb survival to weaning/market, and weaker survival.
How long is a ewes gestation period?
5 months.
Lamb at day 147.
Embryo implants at day 45.
When does weaning usually occur in sheep enterprises?
From 8 weeks depending largely on the farm.
Day 60-120 post lambing.
How do you measure reproductive performance?
Weaning %, marking %, reproduction rate, fertility, fecundity.
How do you determine weaning %?
Lambs weaned/ewes joined
How do you determine marking %?
Lambs marked/ewes joined
Can vary between the number of pregnant ewes or the number of ewes mated depending on the farmer.
How do you determine reproduction rate?
Live lambs at joining/ewes joined
How do you determine fertility?
Ewes lambing/ewes joined.
How do you determine fecundity?
Average litter size of lambing ewes.
What is a normal level of reproduction in sheep flocks?
For adult merinos joined in Autumn expect a marking % of 95-100%.
Maiden ewes 75-80%.
Varies greatly depending on climate, environment, etc.
Crossbreed ewes will have higher % as they have higher ovulation rates.
What can be some reasons for high return to service rates in ewes?
Poor ram fertility.
Oestrogenic factors in pasture - clovers.
At what age do Rams reach puberty? How long are they usually kept in the flock?
Puberty at 6 months.
Normally sold/bought at 12-15months, common to buy new Rams yearly.
1/3 Rams over 7 years have low fertility, this is quite old for a ram and so is unusual to see this issue.
Discuss important factors to consider in terms of ram health.
4 Ts - teeth, tossle, toes, testes.
Disease - buying from saleyards is high risk, better to buy direct from stud where disease status can be confirmed. Severe production limiting factor if not managed.
Conformation
Acclimatisation, heat stress.
Shearing - 2-4 months wool at joining as is less weight to carry and decreased susceptibility to fly strike.
Condition score - good but not fat.
Spermatogenesis - 48 day cycle
Nutrition - sperm production is related to teste size and nutrition. Feeding lupins (500g/d 7wks prior to joining increases sperm-safe and low risk of acidosis compared to other grains).
Genetics - scrotal size, high wrinkle leads to increased chance of heat stress.
Season
Joining % and length of joining - 2 opportunities to mate, 5-6wks in Autumn, 8 wks in spring.
