Agriculture Reference
In-Depth Information
Environment and management
Sows within a farrowing room will synchronize their nursings (Wechsler and Brodmann,
1996) due to the auditory stimulus from the other animals. When litters are subjected to
a continuous loud noise (such as that from a fan), piglets perform less teat stimulation
thereby decreasing milk output (Algers and Jensen, 1991). The playback of recorded sow
suckling grunts was shown to stimulate nursings (Stone
et al.
, 1974), and to increase weight
of piglets at 14 days of age (Cronin
et al.
, 2001) or have no effect on piglet growth until day
27 (Fisette
et al.
, 2004). The concept of decreasing nursing intervals to increase sow milk
yield is a valid one, yet the means to carry it out in a commercial situation has yet to be
achieved. Other environmental factors, such as heat stress and photoperiod, are known to
affect sow lactation performance. High ambient temperatures, ranging from 27 to 32 °C,
were demonstrated in numerous studies to decrease sow milk yield (Farmer and Prunier,
2002). There are indications that the use of an extended photoperiod in farrowing units
may have beneficial effects on pre-weaning piglet growth, yet results are inconsistent.
Subjecting sows to 16 h of daily light instead of 8 h throughout lactation either led to
increases in growth of suckling piglets (Mabry
et al.
, 1982) or had no effect on piglet
growth (Gooneratne and Thacker, 1990; Greenberg and Mahone, 1982). Management of
first litter sows can influence their productivity in the subsequent lactation. In a study
where piglets from second-parity sows could suckle teats that were either used in first
lactation or that were never used previously, piglets suckling teats that had been used
previously had a greater body weight on day 56 (Farmer
et al.
, 2012). Housing can also
influence milk yield. For example, farrowing pens providing easier access to the udder
lead to a greater milk intake by piglets (Pedersen
et al.
, 2011).
Nutrition, mobilisation and body condition
Most nutritional studies on lactating sows have concluded that feed composition and
feeding level have no impact on sow milk yield, which is surprising, because as much
as 50 to 60% of dietary nutrients are being secreted into sow milk (Theil
et al.
, 2004).
Reasons why most nutritional studies fail to demonstrate any impact on milk yield are
likely that: (1) improper feeding is compensated by body mobilization; (2) milk yield
is difficult to quantify; (3) the genetic potential for producing milk varies between
individuals; and (4) many different factors affect milk yield, including litter size, stage of
lactation, feeding level, feed composition, parity, breed, body condition, sow metabolic/
endocrine status, and environment (temperature, light regimen and housing). Nutritional
studies that have documented impact of feeding have typically applied severe restriction
of essential nutrients or energy.
Severe restriction of dietary lysine (from 45 to 15 g/d) reduced sow milk yield from
8.79 to 7.87 kg/d on day 8 and from 9.56 to 7.42 on day 18 of lactation (Kusina
et al.
,
1999). However, reducing lysine supply to gilts from 48 to 27 g/d had no impact on
their milk production even though the daily supply of lysine required to minimize body
mobilization was estimated at 45 g/d of digestible lysine (Touchette
et al.
, 1998). Dietary
contents of valine below 5.5 g of apparent ileal digestible lysine per kg of lactation feed
have been shown to reduce milk yield (Paulicks
et al.
, 2003). Requirements of essential
