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Synchrony Programs
The decision to begin a synchrony program with your herd shouldn’t be taken lightly.
Synchrony can improve fertility; with studies showing a 6 week in calf rate (ICR) of
68% with Fixed time AI (FTAI), compared to 47% without a synchrony program. The
process should begin 40 days post calving which is when cows typically begin to start
cycling again. The cow oestrus cycle is 21 days (range 18-24) and consists of 4
stages. It’s important to understand that cows will be at different stages of this cycle at
any one time, with synchrony, we aim to have cows as close to each other as possible.
First service conception rates can be lower but overall fertility is increased.
Synchrony aims to improve fertility, but in isolation, it is not the answer to poor
fertility. Factors such as nutrition, body condition score, insemination technique, bull
power, heat detection and heifer growth all influence overall fertility. The aim of
synchrony is to make a sub fertile cow more fertile, allow for better use of labour and
make heat detection less crucial.
Why synchronise:
 Helps get cows in calf as soon after calving as possible.
 Less reliance on heat detection. Errors with heat detection are detrimental as
for every 10% decrease in effective heat detection, the 6 week ICR decreases
by 5%.
 Minimises late calving cows
 High producing dairy cows unfortunately often display poor fertility.
 Synchrony is a treatment for non cyclers. Treated non cyclers achieved a 25
day ICR of 50% compared to 10% if untreated. It also allows for early
detection of problem cows.
 Earlier calving cows have more time in peak lactation, thus increasing early
lactation milk production.
 Increased numbers of replacement heifers produced.
Down sides of synchrony programmes:
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More expensive in terms of labour, insemination, semen and drugs.
Large amounts of labour required in one day.
Accidents: It is crucial to get your drugs and days correct as mistakes can
result in disasters.
Types of synchrony programmes:
1. Double PG/Why wait: Prostaglandin is the cheapest and most commonly
used synchrony treatment. It’s usually used 11 days apart to form 2
synchronised groups. It relies on adequate heat detection to determine timing
of AI. It doesn’t work on anoestrous cows. We expect a cow to come on heat
2-7 days after injection but only if she has a CL and is already cycling. Cows
without a CL at the first PG should respond to the second injection.
Day 0
PG all
Day 11
PG all
Day 12-16 Observe and AI (most will come on heat on days 13-14)
or
Days 1-6
AI cows as they come on
Day 6
PG cow that haven't been joined, but calved more than
35 days.
Days 6 - 12
Day 14
AI animals as they come on heat.
Vet check cows calved > 35 days
that haven't been seen on heat or joined.
2. Ovsynch: Oldest and most commonly used FTAI protocol. Better synchrony
than PG programs and no need for heat detection. Expect 25-40% first round
conception rates. Pregnecol may be added.
3. Presynch Ovsynch: The down side of an Ovsynch program is that at the time
of the 1st GnRH injection there will be a wide variation in follicular
development within the herd. Presynch aims to bring the follicular
development into synchrony, so that when we give GnRH we can be more
certain that subsequent ovulation will produce an egg and CL of higher quality
and likely to result in pregnancy. The downside is a lot of time is required
prior to mating start date (MSD). It’s not as expensive as Prosynch and also
has ability to induce cycling in anoestrous cows.
4. Prosynch: This involves the use of an intravaginal device such as a CIDR or a
CUEmate. It achieves tight synchrony and is the gold standard for treatment of
non cyclers. You can expect 25% conception rate to 1st round and 50% ICR at
25 days. Pregnecol can be combined with this protocol.
5. Adding Pregnecol to your synchrony programme: Pregnecol is used to
promote rapid growth of follicles and help them reach maturity. This means
that, when we cause ovulation, the follicles have had the best chance to
achieve sufficient size and maturity. It is most beneficial in cows over 6 yo
and in 2 yo heifers
6. Synchrony programmes for heifers: In heifers oestradiol (Cidirol) can be
used as a replacement for GnRH. It is potent at inducing expression of
oestrous but it’s critical that the time between the last injection and AI is 5256hrs, especially when using sexed semen.
7. Sexed semen considerations: Fertility is average when using sexed semen
and its use should be restricted to heifers and your most fertile cows.
8. DO NOT RE-INSERT: Simple resynchrony where the CIDR/Cuemate is
reinserted the second round (between days 14-21) was quite popular years ago.
New evidence available shows that reinsertion should not be done, as it
drastically lowers second round conception rates.
9. Early pregnancy testing: This is important in order to identify those cows
that didn’t respond to the synchrony program.
It can be confusing with all the different drug names that sound alike. But it’s critical
that you make the distinction as getting it wrong can have disastrous results. If you are
confused or unsure when to give which drug when please contact one of our cow vets.
Drug active
GNRH
PG - Prostaglandin
Progesterone
ODB -oestrodiol
Trade names
Ovurelin, Gonabreed
Ovuprost, Estrumate, Juramate,
Cuemate, CIDR
CIDIROL, Bomerol (heifers only)
Factors to consider when choosing the right Synchrony program for you:
 Available labour: FTAI requires lots of labour on one day. Avoid starting on
Thursdays as this often means AI will occur on a Sunday.
 Input: PG programmes require little input, while CIDR programmes will
require yarding 5 times.
 FTAI programs are best done with AI rather than a bull.
 Are you expecting large numbers of non cyclers? If so then consider a
CIDR/Cuemate program.
 Are there lots of old cows? Pregnecol may be useful.
 Available time: Presynch may not be feasible in most strictly seasonal herds.