Agriculture Reference
In-Depth Information
62%) up to the point where dietary levels reached 14.7 MJ DE/kg and 248 g/kg protein.
Thus, increasing the dietary energy and protein contents of lactation diets resulted in an
improvement in sow productivity during early parities.
Optimal water intake
Due to high barn temperature and the production of about 10 kg of milk per day, water
requirements of sows are high. Fraser and Phillips (1989) showed that in systems with
a nipple drinker, delivery of 0.7 l/min of water for sows around farrowing and in early
lactation can be dramatically low. Associations were found between water intake of sows
and growth and mortality of piglets. Therefore, it is advised to supply water
ad libitum
during lactation and to regularly check the water output of nipple drinkers which should
be 2 to 4 l/min.
17.3.2
Lactation length
The choice for a certain lactation length usually is not based on reproductive
performance, but on factors such as efficient management, good piglet performance or
welfare regulations. Lactation lengths vary enormously between farms across the world.
In the US, the majority of farms wean at 18-21 days of lactation (Knox
et al.
, 2013),
whereas in the European Union weaning is not allowed within 21 days and, for example,
in Finland weaning is not allowed within 28 days. In 1982, Varley reviewed the effects
of lactation length on subsequent reproduction. In his study, the weaning-to-oestrus
interval increased from the usual 7 days post-weaning when sows were weaned at less
than 3 weeks of lactation, to 8 to 16 days when sows were weaned on day 10 of lactation.
Lactation length did not influence ovulation rate, but it increased embryo mortality
around the time of implantation, thereby decreasing litter size, when it was shorter than
21 days. The negative consequences of short lactation lengths on litter size were attributed
to the compromised uterine recovery after weaning. The question still remains as to
whether these findings will still hold with our modern sows, for which genetic selection
not only changed reproductive performance (reduced weaning-to-oestrus interval,
increased ovulation rate and increased litter size) but also altered body composition
(higher lean muscle tissue, lower back fat levels).
Little is known about the reproductive physiology of sows with different lactation
lengths. Willis
et al.
(2003) compared sows on a 14 day vs. a 24 day lactation and
found a lower LH-pulsatility pre- and post-weaning, consistent with an hypothalamus-
pituitary-ovarian axis that is not fully recovered, in sows with the 14 day lactation.
Concentrations of FSH were also greater and there was a delay in the post-weaning
increase in oestrogen concentrations with weaning at day 14, consistent with a suppressed
follicular development. A few studies analyzed farm data on sow performance in relation
with lactation length. These studies show that the weaning-to-service interval increases
when lactation lengths are shorter than 21 days (Belstra
et al.
, 2004; 2001; Knox and
Rodriguez Zas, 2001; Tummaruk
et al.
, 2001). Sows with short lactations that did not
show oestrus by day 6 after weaning, had consistently smaller follicles at weaning and at
3 days post-weaning (Knox and Rodriguez Zas, 2001), suggesting a suppressed follicle
