Understanding reproductive hormones is often confusing! And a basic understanding of those hormones is essential to know how to use synthetic hormones in a swine breeding program. So some very basic information needed:
Follicle Stimulating Hormone (FSH) and Luetinizing Hormone (LFH) – Two hormones released from the pituitary gland that act on the ovaries and stimulate follicle development and ovulation. PG 600 acts as synthetic FSH and LH.
Progesterone – A hormone secreted by the ovaries that prepares the uterus for pregnancy. This hormone is at high levels during the middle and towards the end of the animal’s normal estrous cycle. If she becomes pregnant, progesterone remains high and maintains the pregnancy. MATRIX acts as a synthetic progesterone.
Therefore, PG 600 works to stimulate ovulation in a sow or gilt. Around 4-6 days after giving PG 600 to an animal that is not cycling on her own, she should come into heat and subsequently ovulate. We know that ovulation occurs about 2/3 of the way through the standing heat period – or towards the end of standing heat.
It is IMPORTANT to note that PG 600 WILL NOT WORK in an animal that is already normally cycling on her own. The PG 600 will not work to overcome her natural hormonal cycle to make her come into heat in any other timing other than when she will according to her natural cycle. This is why we only use PG 600 on gilts that have not yet cycled or sows that have quit cycling for some reason.
PG 600 can sometimes used on sows at weaning (especially in the summer when wean to first service interval is longer) to shorten the time to standing heat.
PG 600 is sometimes administered the day after the last Matrix dose to induce a stronger standing heat response. It may also induce a first standing heat if the animal was not actually cycling at the time of Matrix feeding.
Since Matrix works as a progesterone, it can be supplemented to extend a heat cycle of a cycling sow or gilt. By using Matrix, we can delay her return to standing heat and use this as a tool to synchronize heat cycles among multiple animals. She will typically come into heat 5-6 days after the last Matrix feeding.
In a group of random cycling animals, Matrix can be fed for 14 days to all animals to synchronize their heat cycles. This timing ensures that all animals respond to the supplemental hormone, regardless of where they were at in their natural cycle.
Since progesterone is naturally high during the middle of her cycle, we do not have to feed Matrix until day 16, when the natural progesterone will start to fall. Then keep her on Matrix until 5-6 days before desired breeding.
When feeding Matrix, it is extremely IMPORTANT to ensure that each individual animal gets her full daily dose. Underdosing can cause cystic ovaries and also result in poor synchronization results.
Matrix can also be used to delay farrowing. We don’t typically want to do this, but it has been a useful tool during PEDV breaks to allow the development of herd immunity prior to baby pigs hitting the ground.
Some bottom line take home points:
NO hormones can be used to shorten the 21 day cycle of a sow or gilt – we can only lengthen it.
PG 600 only works in non-cycling animals.
Matrix only works in animals that are currently cycling.
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