Principles of Monitoring Fertility Flashcards
Fertility is often a major driver of profitability in livestock businesses
Monitoring fertility at population level is a key part of managing this because?
- Detect problems early
- Minimises losses
- More time to put right
What are the fertility outcomes for dairy?
Dairy: calve each cow as close to once a year as possible with minimum culling
What are the fertility targets for sheep and beef?
Beef/sheep: target calves/lambs per dam per year in tight breeding season with minimum culling
- Beef – one calf per cow
- Sheep – depends whether upland or lowland
What are the fertility targets for pigs?
•Pigs: maximise piglets weaned per sow per year with min culling
Fertility outcomes may not be the best way to monitor fertility why?
- May be slow to change
- Lag time such as 9 months in cows before we realise something is wrong!!
- Often don’t show where the problem is
Will show something is starting to go wrong – but wont show exactly where the problem is
Discuss the pig production cycle?
- Pig cycle starts with farrowing and has piglets with them until weaning (around 28days).
- When weaning happens they get into oestrus within a few days
- Then have gestation period – and piglets
- Interval farrowing to weaning – depends of farm
- If it takes more than 1 insemination to get pregnant – 21 days to cycle!
- 3 months, 3 weeks, 3 days
Look at this?
- For sow that conceives at first service… What we hope will happen
- Farrowing to weaning
- Can measure weaning to oestrus but pigs are good
- Gestation period
- Add the above up = cycle
- Just because they have multiple gestations in a year – they think how many production cycles can we get in a year rather than how long is the cycle
What are the objectives for pig breeding units?
If we are acheieving our number of piglets per sow per year we don’t need to look into it otherwise have to look:
How many litters per year?
How well back into oestrus?
How well detection of oestrus?
How many services?
How many abortions before full term?
Look at this diagram which shows:
If you’ve got ___(black), then it will show up as ___ (red)
Discuss monitoring sheep fertility?
- Extremely seasonal
- Expectations are high - should get pregnant within first 2 cycles of mating! Don’t really know its gone wrong until it really has
- Don’t make the same mistake as last year
- Relatively restricted opportunity to monitor “this season”
Things to assess in sheeps last season performance?
Last season’s performance
Lambing %age
- (lambs born alive / ewes put to ram) x 100
- Target 120-200% (lowland>upland>hill)
- Lowland 2 lambs per ewe put to the lamb
- Others will be 100% as you only want them to have 1.
Weaning %age
•(lambs weaned / ewes put to ram) x 100
Length of lambing period
- 95% should be within 2 cycles (ie 35 day period). 1 cycle – 17 days.
- Poor fertility – but leave lamb in for ages. They will probably get pregnant eventually. But will cause yourselves problems – grass growth problems, infection risk long lambing period.
Barren ewes
- (1-(ewes lambing / ewes put to ram)) x 100
- Target <2-3% (sheep are good at getting pregnant)
How can the current seasons performance be monitored with regards to sheep?
This season’s performance
- Use of raddle
- Identifies ewes returning to serve
- Identifies ewes not served
- Change the crayon colour at cycle times so you know which cycle conceived/also identify those still at the end of the season mating
- Use of scanning
- Identifies empty ewes at end breeding season
- Estimates lambing %age
- Common problems are nutrition (energy/ micronutrient) and ram factors – especially those just on grass.
- Ram factors are important too
Discuss fertility monitoring in beef cattle?
- Almost all herds seasonal calving
- Major objectives…
- One calf per cow per year
•90% herd should calve within 9wk period
with 65% in first 3wks
- <5% barren/empty cows
- Twins are generally trouble in cows
How can you analyse beef cattle breeding?
- Easy to analyse last breeding season – use centrally devised database
- Calving distribution
- Can get data from CTS online (cattle tracing scheme) – telling the government where all the cattle are in the UK. The vet can get permission from farmer to view records.
Discuss beef cattle fertility monitoring?
- Can be difficult to work out what’s going on this season!
- Vast majority of herds run bull(s) with cows
- No need for stockpeople to detect oestrus
- Usually no recording of serves/heats or use of AI
- Often have PD session after end of breeding season (+/- at/during)
- Leave bull in for 12 weeks and wait 6 weeks to PD – then vet says how far gone
What often goes wrong with beef cattle fertility?
What often goes wrong?
- Post-partum anoestrus – whilst the calf is suckling hard to get back into oestrus
- Low pregnancy/conception rate
- These can be distinguished at PD – examine ovaries of negative cows
- Unexpectedly high empty – ovaries are all cycling and normal with evidence of CL – problem is conception rate!
- If you scan all ovaries are tiny with no CL or follicles – more likely to be post partum anoestrus. Hard with this though as the cow may have resumed cyclicity since being in post partum anoestrus
- Nutrition (energy/ micronutrient), dystocia and bull factors are common causes of poor performance
Although calves are a potential for profit Milk is the biggest – the shape of the curve is very pointy. Massive gap between calvings – they wont be in the highest lactation area and will not be justifying the cost of keeping and feeding them
Dairy production cycle – cows aren’t as good as pigs and sheep to get pregnant. Takes more serves – probably as they are making milk too. Discuss?
Outline when cows are served, how often and what we can measure to look at efficiency and productivity?
Served every 22 days until pregnant
Voluntary wait period – gap before we consider getting cow pregnant. Stops short lactation. 35 – 50 days is typical for wait period in UK – depends on farm
Measure – calving to 1st service, calving to conception and gestation period
Calvin interval – number of days between 2 successive calvings. Calving index – calving interval averaged across the herd.
Cows will milk throughout all of this (cf pigs) Then dried out for a set period before due (decided by farm)
Interpret this dairy cow data?
Red – successful
Then have gestation
65 days calving to 1st service
Calving interval – 387
Calculate calving index mean?
– 380 days. Aim for 360-375days
- Farm culling policy can affect or “manipulate” calving index…
- This is often seen in seasonal calving herds:
- Cows not pregnant at the end of a set “breeding season” each year are culled
- E.g. They will breed for 12 weeks and then those not in calf – culled. This therefore will make your index lower as they don’t have the chance to take ages
- Imagine if our herd decided to cull all cows that weren’t pregnant by 100 days after calving
Discuss calf index and culling?
- Culling if empty at 100 days after calving
- Calving index = 353 days, cull rate = 50% as cant get pregnant in the time
Why not just monitor calving index and culling then?
Very slow to respond to changes
•Don’t show where the problem is
Alternatives?
•Consider what needs to happen to have a good CI/low culling… (good fertility performance)
What makes good fertility?
What makes godo fertility performance in dairy cattle?
Discuss measuring heat detection?
Define first service submission rate
First service submission rate
- Measure of: are cows getting their first serve “on time”?
- % of cows getting first serve within 24 days of VWP ending
- Target 80%
- All cows cycling at end of VWP - she should have a heat within 25 days. So what % does this happen to? – that is the first service submission rate
What does this show us?
- Voluntary wait period = 50 days
- First serve sub rate = 3/4 = 75%
- 24 days interested In is the yellow box. Top cow – success. 2 – fail (not until outside). 3 and 4 – success.
- This measure doesn’t care if they get pregnant – just if they are served in the first 24 days
- Roughly saying – farm can detect 75% of oestrus
Discuss Inter-service intervals?
Need to identify those who need to serving again
Look at the days between successive serves
2 intervals at 21 days
Cow 2 – 2 intervals at a gap of 42 days (she probably had a heat in the middle that was missed)
Cow 3 – pregnant fist time so no inter service intervals
Collect all the intervals across the herd! Look at how they compare to what we expect. Normal cycle is 18-24 days so hope the intervals fall into this
Look at this Inter-service intervals graph?
What goes wrong with heat detection?
Discuss measuring pregnancy rate in dairy cattle?
Proportion of serves leading to a pregnancy
- Outcome ideally via PD
- Can also use non-return to serve or next calving
- Tells us whether the serves worked or not
- Also commonly known as “conception rate”
- Technically not as they may conceive and loose it – but will not be recorded in this rate
- Target >35-40%
- Associated with milk yield
•Lower targets for
higher yielding herds?
•It is the pregnancy rate – but will hear it called conception rate
What goes wrong with rates of pregnancy?
What goes wrong?
- Many factors
- Most common – nutrition and within that – energy balance
