Synchronisation Programs For Dairy Cows and Heifers

Why synchronise heats?

Synchronisation programs have been widely promoted to increase the reproductive efficiency of dairy herds and to facilitate the use of artificial insemination in milking cows and maiden heifers.

The aim of a synchronisation program is to have as many cows joined at one time as possible.

Improve heat detection.: The large number of cows on heat at one time means that some of the less sexually active cows are more inclined to show signs of heat. The period of intense heat detection can be reduced.
Ease of calving management.: The tighter calving pattern reduces the number of days required for close observation of springers.
Extended interval from calving to joining.: An early calving date will give an extra 5 to 10 days prior to the start of mating increasing submission rates and conception rates.
Labour costs.: If cows can be joined quickly and do not need to be joined again, the amount of time that can be dedicated to joining can be reduced.
Early lactation milk production.: More cows are calved down early, and a greater volume of milk can be sent at the start of the season. We can expect that synchronised cows may get an extra 5 to 10 days lactation. This is equivalent to an extra $20 to $50 dollars per cow at the start of the season.
Increased number of replacement heifers.: A successful synchronisation program may result in extra calves born to AI and hence extra replacement heifers. The heifers can be raised in batches of uniform age. The cost of purchasing replacement heifers is reduced as is the risk of introducing disease.
Decreased need for induction.: Calving induction can cost up to $100 per cow induced when we take into account the reduced milk production, the lost calf, increased time to clean and get back in calf, as well as the increased risk of illness. If pregnancy rates can be increased in the early joining, significant savings are made.
Early detection of non-cycling cows.: Non-cycling cows can be detected early in the AI period and treated at this time.

Heifer AI.

When deciding on whether or not to join the yearling heifers to AI there are a few factors that should be considered.

Firstly, why artificially inseminate heifers?

The benefits of AI joining the heifers include:

Increased rate of genetic gain.
Synchronisation of heifers without the need for extra bulls. 90% of treated heifers will cycle within 24 hours. The benefits of an intense mating and calving pattern might be the reason for a synchronising program. If natural mating is desired a program can be staggered over several days.

The disadvantages of heifer AI:

Reduced calving rates to AI compared with natural mating. One survey of heifers showed that higher percentage of naturally bred heifers calved within 21 days (67%) compared to those synchronised and joined to AI (55%).
Increased calving difficulties in friesian heifers mated to friesian sires. Although a great deal of attention has been put into achieving satisfactory calving weights and the search for ease of calving sires, it is difficult to achieve easy calving for all friesian heifers joined to friesian sires compared to jersey sires.
Losses associated with calving difficulties in friesian heifers mated to Friesian sires. Some calving difficulties can be minimised by good heifer managemnt. However, problems are still experienced by many farmers. The losses include decreased first lactation production due to trauma, poor reproductive performance in following seasons and loss of heifers due to calving paralysis.

Synchronisation Programs for Heifers

Remember

Because of the synchrony achieved with these programs, returns to service are also batched closely over only a few days. A rate of 5% bulls (1 per 20 heifers) should be sufficient in most cases until round 2 is completed. The additional bulls that are to be used over the milking herd after AI, could be used on the heifers for the first 3 weeks to overcome this problem.

CIDR Programs for heifers

Controlled Internal Drug Release (CIDR) devices slowly release progesterone when placed in the vagina. They produce a tight synchrony and are easy to administer.

CIDRs delay the maturation of follicles by maintaining high progesterone levels for a period of 8 to 10 days. When the progesterone is removed follicle development resumes and ovulation follows 24 to 72 hours later.

Day 0	CIDR and capsule in all heifers.
Day 6	PG all heifers (2 dose - 2.5ml)
Day 8	(pm) Remove all CIDRs and tail paint.
Day 9	Observe and AI. Very few will cycle
Day 10-11	Observe and AI (most heifers will cycle on these days).

CIDRs can be reinserted at day 16 for 5 days to re-submit heifers failing to conceive to first insemination. These heifers will be on heat on day 21 or 22.

Prostaglandin programs for heifers

Prostaglandins are the most commonly used drug in synchrony programs today. The ability to remove the corpus luteum between days 5 and 16 of the oestrus cycle provides the opportunity to influence the onset of oestrus of 75 per cent of cycling heifers with one treatment.

A number of different programs are used to synchronise maiden heifer heats.

Double PG program

This traditional program involves treatment of heifers twice at an eleven day interval. The first treatment will bring all heifers into the 5 to 16 day period by the time of the second treatment.

In practice, 90 percent of heifers cycle within the period 2 to 5 days past 2nd treatment.

Day 0	PG all heifers
Day 11	PG all heifers and tail paint
Day 12-16	Observe and AI (most heifers will cycle on days 13-14)

Five day AI - PG program

This program takes advantage of the five day non response period early in the cycle. By submitting heifers to AI in the first 5 days, all heifers not mated by 5 days will be between days 6 and 21 of their cycle. Treatment of this group with PG will result in all responsive heifers on heat in the subsequent 2 to 5 days.

About 75% of heifers will be treated with PG in this program. Up to 10 days of observation and AI are required to achieve high submission rates.

Day 1	Tail Paint and AI
Days 2-4	AI
Day 5	AI, PG all heifers not yet mated.
Days 6-10	AI

PG - AI Program

This program reduces the number of days of observation and AI to 5 however at a cost to submission rate.

Heifers between days 1 and 5 of their cycle will not respond to PG so will not come on heat in the ensuing 5 days.

Day 1.	AI all heifers on heat, tail paint and PG others
Day 2-6.	Observe and AI.

Comparative Costs of Programs (1998 prices)

Program	Cost/animal treated	Cost/50 heifers	No. Days AI
Double PG	$8	$400	3
5 day AI -PG	$4	$150 (75% treated)	10
CIDR-PG	$15	$750	2

Prostaglandin programs for milkers

Modified why wait (Six day AI and PG)

This is a tried and true program that is recommended for most herds. All cows are inseminated when they show signs of heat. Cows that have been calved four weeks and have not been joined are injected with PG.

Days 1-6	AI cows as usual.
Day 6	Inject only cows that haven't been joined And that have been calved > 4 weeks
Days 6 - 12	Join cows as they come on heat. Most cows should come on during days 8 - 10.
Day 14	Vet check any cows calved > 30 days that haven't been joined.

Why wait program

Premating heats are collect for a period of 11 days prior to the start of mating. Cows are injected with PG six days after they are seen on heat and they will cycle within the first 10 days of mating. Cows are inseminated when they are on heat. This program is time consuming but only cows that are cycling will be treated.

For both the Modified why wait and why wait programs cows need to be already cycling. About 40% of the herd calved greater than 30 days will be treated in a why wait program, while 70% of the herd will be treated in a modifed why wait program.

Timboon Veterinary Group