Agriculture Reference
In-Depth Information
129
Average duration
of farrowing
255 ± 126 min
Farrowing sows
148
Pregnant
Weaned
AI
19
Average duration
of farrowing
268 ± 142 min
Average duration
of farrowing
357 ± 207 min
Not pregnant
Figure 10.3. Sows which failed to get pregnant at first insemination were having a previous duration of
farrowing 100 min longer than those who got pregnant (Oliviero
et al
., 2013).
is relatively short, usually between 18 and 28 days and the weaning-to-oestrus interval
is, on average, 5 days. The interval between parturition and subsequent insemination
is therefore much shorter than under natural conditions, which may allow factors that
negatively influenced the physiology of parturition to interfere at post-weaning oestrus.
Although histological involution of the uterus is completed within 3 weeks after farrowing
(Belstra
et al.
, 2005), the period between parturition and subsequent insemination is
relatively short. Possibilities as to what physiological mechanisms may be negatively
affected by environment include development of follicles, as well as impairment of
oxytocin activity and/or oxytocin receptors modulation. However, further research on
oxytocin and fat metabolism are needed to substantiate this.
10.6.1
Human intervention into physiology of farrowing: induction of
parturition and oxytocin administration during the process of
farrowing
Prostaglandins are widely used to induce farrowing in sows. When an injection of
prostaglandin is given in the morning, a group of sows is expected to farrow at daytime
during the following day. While it is tempting to use prostaglandins to synchronize
farrowings of sows in order to ensure supervision of farrowings in the day, the use of
prostaglandins for this purpose is known to have risks. Piglets may be born immature
since they are induced to be born before term. This is setting greater demands in terms
of management of newborn piglets. It is also known that farrowing induction increases
the risk of sows showing prolonged interruption of contractions (Smith, 1982) and
post-partum dysgalactia syndrome (PDS, Papadopoulos
et al.
, 2010). Furthermore,
induction of farrowing increases the risk of certain congenital diseases such as spayleg.
The accepted condition in veterinary medicine to recommend farrowing induction is
overdue pregnancy, especially in gilts. It is recommended that farrowing be induced if
pregnancy exceeds 117 days in gilts.
Oxytocin may be given to stimulate uterine contractions and milk let down. In both
cases, a dose of 5-10 IU/sow (IV) may be used as complications are observed, and it can
be repeated up to 4-5 times at 2-3 hourly intervals (Martineau, 2005). There should be
at least 30 min between two subsequent injections. In fact, in most cases 5 IU appears
