Agriculture Reference
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insemination have also been developed and are increasingly used. After fixating the
pipette in the cervix, a smaller tube is extended for approximately 10 cm from the centre
of the pipette into the uterine body just before the bifurcation to the uterine horns, and
a volume of 40-60 ml (containing 1-2×10 9 sperm cells) is inseminated. Post-cervical
inseminations reduce the number of sperm cells needed for good fertility (Hernández-
Caravaca et al. , 2012; Watson and Behan, 2002), due to reduced back flow of sperm
cells and reduced loss of semen in the cervical folds (Hernández-Caravaca et al. , 2012).
Post-cervical inseminations are currently not advised in gilts as they have a lower
catheter passage rate and a higher chance of cervical damage and associated low fertility.
Also the management around post-cervical inseminations is different. For example, in
contrast to cervical inseminations, boar contact during post-cervical inseminations may
hinder passage of the cannula. The choice for either cervical or post-cervical artificial
insemination may differ between farms, depending on the genetic value of the boar, the
costs of semen and pipettes, the labour costs, and the reproductive performance using
both techniques.
Fixed-time artificial insemination
Since ovulation time cannot be sufficiently predicted, sows need to be inseminated every
day of standing oestrus, to allow at least one insemination in the optimal 24 h window
preceding ovulation. Most sows are therefore inseminated 2-3 times during oestrus. If
ovulation time can be successfully induced in sows, fixed-time artificial insemination can
be applied. This reduces the labour associated with oestrus detection and insemination and
also results in a more efficient use of breeding boars. Recently, Driancourt (2013) reviewed
the status of fixed-time artificial insemination and the major aspects are as follows. Either
LH agonists (such as human Chorionic Gonadotropin-hCG or pLH) can be used to mimic
the pre-ovulatory endogenous LH surge or GnRH agonists (such as buserelin, goserelin,
depherelin and triptorelin) can be used to induce the pre-ovulatory endogenous LH surge.
To allow for appropriate timing of the induction, these products are usually administered
at a fixed time after a treatment period with a progesterone analogue (gilts), at a fixed time
after weaning, or at the onset of oestrus (sows). If timed appropriately, ovulation will take
place 35-44 h later. Since sows may show variable post-weaning follicle development and
oestrus onset, depending on factors such as parity, lactational weight loss, season, genetics,
and lactation length, it is a real challenge to develop a strategy that will apply to all sows
under all these conditions. Fixed time artificial insemination strategies are currently being
developed by pharmaceutical companies and evaluated.
17.6
Overall conclusions
Management during the lactation period largely affects subsequent reproductive
performance. Substantial lactational weight loss should be avoided, especially in first
litter sows, and lactation length should preferably be more than 21 days to allow sufficient
follicle development. Lactation management strategies such as intermittent suckling and
split weaning may stimulate lactational follicle development and thereby post-weaning
oestrus onset. This is achieved via the combined effects of a reduced suckling intensity
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