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ANS 00-810S |
Feeding Recommendations for Gestating Sows
Proper nutritional management of sows is important
to maximize the number of pigs per sow per year and to maximize sow longevity. This fact
sheet will detail current research and feeding recommendations for gestating sows.
A simple diagram (Figure 1) of the metabolism in gestating sows is shown below. Nutrient
requirements of sows can be calculated from the metabolic processes taking place during
gestation.
For example, metabolizable (ME) energy needed for maintenance (basic body functions) is
dependent on sow body weight, and can be calculated from the following equation: ME (kcal)
= 106 * (body weight in kg)0.75. Energy for uterine growth (fetuses, fluids and
membranes and empty uterus) and maternal growth (mammary gland and sow body weight gain) can
be estimated based on some assumptions on parity, litter size, weight at birth and sow body
weight. Most of the energy required by sows is due to maintenance as shown in Table 1.
However, during the later stage of gestation a large portion of the energy requirements
will shift towards fetal and maternal development (Figure 2). Typically, requirement
estimates are made for the overall gestation phase and attempts are made to provide proper
levels of nutrition through changes in feed allowance. Estimates for the nutritional
needs of sows are shown in Table 2. These estimates were based on the assumption that a sow
should reach a certain body protein mass and that a slow development of this protein mass
is desired to maximize protein utilization. Assuming a standard corn-soybean meal ration
containing 1480 kcal of ME/lb. of feed and 0.60% total lysine one can calculate the amounts
of feed needed to meet these requirement estimates. When considering energy, 4.4 to 4.6 lbs.
of feed is required to meet the average energy requirement for gestating sows. To meet
the energy requirement of a sow at mating, 3.9 lbs. of feed is needed, whereas 5.3 lbs. is
required for a sow at the end of gestation. If we do the calculation based on lysine, the
average lysine requirement during gestation can be met with 3.6 to 4.0 lbs. of feed.
The requirement at mating can be met with just 1.6 lbs. of feed, however to meet the
requirement at the end of gestation 5.9 lbs. of feed is needed. To meet the requirement for
both nutrients, it appears that 4 to 6 lbs. of feed would cover the range. This would only
hold true if sows are not excessively thin at mating and are managed properly, under
thermoneutral (proper temperature for sows) conditions.
Function | ||
Maintenance | ||
Uterine Growth | ||
Maternal Growth | ||
Total | ||
Source: Noblet and Etienne, 1987 |
Adapted from Everts, 1994 |
The amount of feed supplied during specific phases of gestation can positively or
negatively affect sow performance. There are a number of specific phases to consider, each
of which will bebriefly described below.
Weaning to breeding
The rate of ovulation, particularly in first litter sows and sows that are very thin,
appears to be influenced by feed intake following weaning. King and Williams (1984) showed
that first parity sows fed 9 lbs. per day between weaning and breeding had greater ovulation
rates and litter sizes (10.0 vs. 8.8) than control sows fed 3.5 lbs. per day. Additionally,
some studies suggest that feeding ad libitum after weaning shortens the rebreeding interval
(Aherne and Kirkwood, 1985; King and Williams, 1984). However, results are not completely
clear because other studies have shown no effect and the response to high levels of feeding
may be related in part to body weight at weaning. Allowing sows to consume feed ad libitum
between weaning and breeding may be a prudent practice, however, to help sows recover from
weight loss during lactation and take advantage of a possible increase in ovulation rate and
shorter weaning to breeding interval.
Early Gestation
High levels of feed intake during the first 3 weeks of gestation may have a negative impact
on embryo survival, particularly in gilts. For example, Dyck et al. (1980) reported a
reduction in embryo survival from 82.8% to 71.9% when feeding levels were increased from
3.3 lbs. to 6.6 lbs daily. The critical time period appears to be 24 to 48 hours after
mating, when embryos migrate to the uterus. Limiting feed intake to 4 to 4.5 lbs. per day
during the first 21 days post-breeding may be a safe practice.
Early to Mid Gestation
This period encompasses day 21 to day 75 of gestation. It is the most appropriate time
period to get sows back into the correct body condition. A body condition score of 3 is
desirable (Figure 3). Body condition scoring should done on a regular basis by monitoring
and scoring individual sows according to the guidelines in Figure 3. Feeding level should
then be adjusted for each sow to target a body condition score of 3. Everts (1994) suggested
a moderate net body weight gain of sows of approximately 75 lbs. for first parity sows, 65
lbs. for 2nd parity sows, 55 lbs. for 3rd parity sows and 45 lbs. for
older sows. Boyd and Touchette (1997) estimated the amounts of feed needed to replenish
body reserves based on body condition scores (Table 3). The level of nutrition from day 21
to 50 may also be important to maximize the number of muscle fibers in piglets born. Primary
muscle fibers set the stage for how fast and lean the baby pig can grow after birth and may
therefore affect subsequent nursery and growing-finishing pig performance. These muscle fibers develop
between day 21 and 50 of gestation and their number can be affected by nutrition. In studies
where feed intake of sows was severely restricted during gestation, growth of piglets after
birth was reduced (Pond et al. 1985, Pond and Mersmann, 1988). The extent to which this
occurs under more practical circumstances is not clear at this point. Therefore, the current
recommended feeding level during this phase of gestation is 4.0 to 4.5 lbs. Of feed for
sows with a body condition of 3. Feed level should be increased by approximately 1.5 lbs
(ie. 6 lbs. total) for sows with a body condition of 2.
Body Condition Score | Body Shape | |
Hips, backbone prominent to the eye | ||
Hips, backbone easily felt without applying palm pressure | ||
Hips, backbone felt only with firm palm pressure | ||
Hips, backbone cannot be felt | ||
Hips, backbone heavily covered |
From: Boyd and Touchette (1997). Calculated for a 400 lb sow to reclaim body reserves from 21 to 80 days of gestation. |
Mid to Late Gestation
The development of the mammary gland reaches the critical stage between day 75 and 90.
This is the period that secretory cell proliferation occurs, which will determine cell
number and ultimately milk synthesis capacity. Excess energy intake (10.5 Mcal/d vs.
5.7 Mcal/d) reduced secretory cell numbers (Weldon et al., 1994) and could, therefore,
reduce milk production. An energy intake of 10.5 Mcal/d would be equivalent to
approximately 7 lbs of feed (corn-soy type diet; 1480 kcal/lb of feed). Therefore, high
levels of feed should be avoided during this time-frame. Sows should be in the correct body
condition at this time if they were properly fed in the early to mid gestation period.
Late Gestation
Fetal weight gain will increase substantially during days 90 to 115 of gestation (Figure 2).
Consequently, nutrient requirements of the sows will increased (Table 2). According to this
table, 5.3 to 5.9 lbs. of feed is required for sows at day 115 of gestation (depending if
calculations are based on energy or lysine needs). However, care should be taken not to over
feed sows during this period either, because it appears to decrease feed intake and
reproductive performance during lactation (Dourmad, 1991; Weldon et al., 1994; Xue et al.,
1997). Doumad (1991) calculated that every 1 lb increase in gestation feed intake was
associated with a 0.64 lb decrease in lactation feed intake (Figure 4). The reduction
in feed intake during lactation was more pronounced during the first week of lactation and
at the highest level of gestation feed intake. An even greater feed intake in gestation of
7.5 to 8.2 lbs./day has been observed to reduce lactation feed intake by 0.95 to 1.30
lbs/day (Weldon et al., 1994; Xue et al., 1997). Therefore, gestation feed intake needs to
be controlled (less than 6 lbs) during the late gestation period to maximize feed
intake and milk production in lactation.
Summary
Proper nutritional management of gestating sows includes feeding the correct nutrient
levels to meet the sow's requirement, but also correct management of feed amounts given to
the sows at critical times in their development. Recommended feeding levels for sows
during the different stages of gestation are summarized in Table 4.
Gestation Phase | Feeding Level |
Wean-Breed | Ad Lib |
Breed-d 21 | 4 - 4.5 |
d 21 - d 75 | 4 - 8 ( To condition) |
d 75 - d 90 | 4 - 5 |
d 90 - d 115 | 4.5 - 6 |
Literature Cited
Aherne, F. X., and R. N. Kirkwood. 1985. Nutrition and sow prolificacy. J. Reprod. Fertil. Suppl. 33:169.
Baker, D. H., D. E. Becker, H. W. Norton, C. E. Sasse, A. H. Jensen, and B. G. Harmon. 1969. Reproductive performance and progeny development in swine as influenced by feed intake during pregnancy. J. Nutr. 97: 489.
Boyd, R. D., and K. J. Touchette. 1997. Current concepts in feeding prolific sows. Proc. 13th Annual Carolina Swine Nutr. Conf., Nov. 11, Raleigh, NC.
Dourmad, J. Y. 1991. Effect of feeding level in the gilt during pregnancy on voluntary feed intake during lactation and changes in body composition during gestation and lactation. Livest. Prod. Sci. 27: 309.
Dyck, G. W., W. M. Palmer, and S. Simarks. 1980. Progesterone and luteinizing hormone concentration in serum of pregnant gilts on different levels of feed consumption. Can. J. Anim. Sci. 63:579.
Everts, H. 1994. Nitrogen and energy metabolism of sows during several reproductive cycles in relation to nitrogen intake. Ph.D. dissertation, Wageningen Agricultural University, The Netherlands.
King, R. H., and I. H. Williams. 1984. The effect of nutrition on the reproductive performance of first-litter sows. 1. Feeding level during lactation and between weaning and mating. Anim. Prod. 38:241.
Miller, H. M. 1996. Nutrition of the periparturient sow. Ph.D. dissertation. University of Alberta, Canada.
Noblet, J. and M. Etienne. 1987. Metabolic utilization of energy and maintenance requirements in pregnant sows. Livestock Prod. Sci. 16:243.
Patience, J. F., and P. A. Thacker. 1989. Swine nutrition guide. Prairie Swine Centre, University of Saskatchewan, Saskatoon, pp. 149-171.
Pond, W. G., and H. J. Mermann. 1988. Comparative responses of lean or genetically obese swine and their progeny to severe feed restriction during gestation. J. Nutr. 118:1223.
Pond, W. G., H. J. Mersmann, and J. T. Yen. 1985. Severe feed restriction of pregnant swine and rats: Effect on postweaning growth and body composition of progeny. J. Nutr. 115:179.
Walker, B., and B. A. Young. 1992. Modelling the development of uterine components and sow body composition in response to nutrient intake during pregnancy. Livestock Prod. Sci. 30:251.
Weldon, W. C., A. J. Lewis, G. F. Louis, J. L. Kovar, M. A. Giesemann, and P. S. Miller, 1994. Postpartum hypophagia in primiparous sows: I. Effects of gestation feeding level on feed intake, feeding behavior, and plasma metabolite concentrations during lactation. J. Anim. Sci. 72:387.
Xue, J., Y. Koketsu, G. D. Dial, J. Pettigrew, and A. Sower. 1997.
Glucose tolerance, luteinizing hormone release, and reproductive
performance of first litter sows fed two levels of energy during
gestation. J. Anim. Sci. 75: 1845.
Reviewed by:
Allen Harper, Ph.D., Tidewater Agricultural Research
and Extension Center, Virginia Polytechnic Institute and State
University.
Kevin Rozeboom, Ph.D., Department of Animal Science, North
Carolina State University
Since June 1, 2000