IVF

A growing number of cattle breeders are using in vitro fertilisation (IVF) to maximise pregnancy rates.

This is the process of harvesting oocytes from donor cows, and creating embryos by fertilising the oocytes with semen in a petri dish.

The embryo is then implanted into a recipient (otherwise known as surrogate cow), or they can be frozen indefinitely. 

Cumbria-based Paragon Veterinary Group has seen embryo production increase at least six-fold in the since its Activf-ET programme began in 2013 and they explained how the process works.

Read the step-by-step guide to using IVF and case study at Trueman Limousins in County Down below.

The first stage is the key addition to conventional embryo transfer. Eggs are removed from the donor cow’s ovary before the ovary naturally releases the oocyte down the fallopian tube.

Using a process called trans-vaginal recovery, IVF works by first removing the dominant follicle in the ovary, allowing the rest to grow.

In a normal pregnancy, the dominant follicle inhibits the rest – otherwise a cow could end up developing dozens of calves in the womb, she adds. With IVF, all follicles are left for six days to develop uninhibited within the ovary in a process called dominant follicle regression (DFR). 

1 Dominant follicle regression

The donor cow is given a local anaesthetic and cleaned with a mild disinfectant and saline solution. This can happen on the farm or at the Paragon facility.

2 Ultrasound needle

An ultrasound-guided needle enters the ovary to remove the dominant follicle and stimulate super-ovulation.

3 Super-ovulation

a three-day course of follicle stimulating hormones (FSH) is administered to stimulate ovaries to produce more oocytes.

4 Ovum pick-up (OPU) 

The donor cow is brought into the crush collection facility, where the temperature is at 27-32C. Oocytes are harvested via trans-vaginal recovery, averaging 10 eggs per collection, and the eggs are matured for 20 hours.

Eggs are placed into insulated chambers at 37C to mimic a cow’s body temperature.

6 Fertilisation occurs with semen

7 Embryos

Resulting embryos are matured for a week in the laboratory, passing through eight different maturation liquids (medias) mimicking the changing pH and gas levels inside the uterus.

8 Embryos can be transferred directly or frozen indefinitely

General guidelines

Recipient cow or heifer

• Avoid lush, wet grass – if grazing, buffer-feed if possible.
• Indoor recipients achieve 5-10% better pregnancy rates that those managed at grass.
• Bought-in stock should have six weeks to settle into new farm.
• Recipients should be managed as a group and major changes (such as spring turn-out and autumn housing) should be avoided for six weeks pre- and-post transfer.
• Good body condition score is essential – 2.5 minimum.
• A long fibre-based diet of hay, big bale silage or straw should be fed.
• Low-protein coarse mix as a supplement is preferable (although not barley).
• Sugar beet pulp can deliver energy and fibre – and be used as a mineral carrier.
• Routine treatments (worming, vaccination, foot trimming) should be avoided at this time.

Cows

• Cows calve easier and so the process can be preferred in beef breeding or with low calving ease bulls.
• Works best on fourth-calvers or younger.
• Select cows with no reproductive or health issues.
• Synchronise cow after peak yield as stress of lactation can reduce pregnancy rates. 
• Pregnant cows can be collected from until about the fourth month of pregnancy.

Maiden heifers

• Heifers average 5-10% better pregnancy rate, compared with cows.
• Should be at least 15 months old, cycling regularly and weigh 350kg (depending on the breed)

Donor cow

Laboratory

Recipient cow

Day 1

Day 2 to 6

Day 7

Day 7/8

Day 8

Day 8 to 15

Day 15

DFR

Superovulation after three-day FSH course

OPU

Egg maturation 20-24 hours

Fertilisation

Maturation in incubator

Must be used within 24 hours if fresh in cow seven days after heat

• 50% of usual amount of semen needed. Half a straw can inseminate around six or seven donors
• About 10 eggs per collection. About 73% of these will be fertilised
• Then 43% will become a viable and freezable
• Fresh pregnancy rate = 58%
• Frozen pregnancy rate = 57%
• 
  

Problem breeders can be salvaged because they can be used as a donor if, for example, they have:

• Uterine damage
• Fallopian tubes blocked
• Scarring

Extend breeding life:

• Collection possible from 10 months to 20 years old and above
• Ovaries can be recovered from abattoir