Management strategies to maximize weaning
­weight
J. C. Pinilla, DVM, MS; J. Geiger, DVM, MS; R. Kummer, DVM, PhD; J. Piva, ­DVM
R. Schott, BSc; N. H. Williams, MS, ­PhD
PIC ­USA, Hendersonville, Tennessee
Introduction
A traditional key performance indicator in sow units is
weaned pigs per sow per year (PSY). In recent years the
industry is considering weaning weight with the same
level of importance. Heavier weaning weights are positively correlated with average daily gain (ADG), and
pounds of saleable pork, feed efficiency.1 For that reason PIC has developed a target for commercial farms:
365 lbs of weaned piglets per sow per year.2 This figure
is calculated based on 27 PSY with an average weaning
weight of 13.5 ­lbs.
Current estimates of the milk yield are 22 to 26 lbs
of milk per sow per day.3 Many factors influence this
number: health, environment (mostly temperature and
ventilation), genetic potential, mammary gland stimulation (lactation length, number and weight of the
nursing piglets), nutrition, feed intake, body condition,
and water ­intake.4
Many producers are struggling to achieve good weaning
weights. This document is intended to provide strategies to wean heavier piglets by maximizing milk production and is based on common practices utilized by
some successful commercial systems in North ­America.
Management strategies to maximize
milk ­production
Number of functional teats as selection criteria in
replacement ­gilts
To maximize litter weaning weight, it is necessary to
select replacement gilts for number and quality of their
teats. The standard is to cull gilts with less than 12
teats, but too many producers do not have this standard
in their operations. To implement it as part of the selection process will require spend some extra doing the
selection in every group of gilts, but it is a cost-effective
way to ­improve.
and genetic improvement will take time; genetic suppliers still have the responsibility to improve this trait
to ensure that the future generations of replacements
have higher probabilities for increased functional teats
(Figure ­2).
Select gilts with high growth rates and breed
them weighing more than 300 lbs of live ­weight
In gilts, there is a significant correlation (0.52) between the ADG in the period from 65 to 195 lbs and
the weaning weight of litters weaned from them.5 The
current higher milk yield potential, and consequently,
the potential to wean heavier piglets could be partially
explained by larger body size and more mammary tissue in the modern genotypes. However, better housing,
better control of environment, modern feeder design,
better nutritional and feeding management, and better
litter management also play important ­roles.
Beside the effects on retention rate and litter size,
the current recommendation to breed gilts after they
achieve 300 lbs minimum (300-330 as range),6,7 to get
farrowing weight to 400 lbs, will produce additional
benefits.8 Gilts bred in that window will gain less body
weight during their first gestation (in total lbs and as
percentage of the initial weight). Consequently, they
lose less body weight during their first lactation and are
able to retain weight, or even gain some weight, during P2 and P3, versus gilts bred at lighter weights. As
a practical consequence, the weaning weights could be
increased due to higher milk ­yields.
Controlled weight gain in ­gestation
The gestating female has the ability to retain nutrients
as body reserves. It is well documented that the excess
weight gain in gestation limits the feed intake during
lactation9 and increases sow’s body weight lose. Farm
management must be aware of that and manage gestation feeding to limit excess body weight gain. During
their first gestation the female should gain around 80
lbs of body weight. From P1 to P6, an average of 35
lbs increase in body weight per gestation is acceptable.
Generally, modern dam lines have more than 12 teats.
In fact, more than 85% of gilts selected in our GN show
14 or more teats at selection (see Figure 1). Recognizing that the heritability of teat number is low (0.1-0.2)
American Association Of Swine Veterinarians, 2008
185
Figure 1: Frequency of teat count in gilts selected at GN level. PIC GNs combined.
Line 03
Line 02
50%
43%
Frequency
40%
38%
30%
21% 21%
20%
10%
0%
22%
18%
8% 7% 8% 8%
0% 0% 0% 0%
10
11
2% 2%
12
13
14
15
16
17
1% 1%
18
0% 0%
19
0% 0%
20
# of Teats
Hain, B and Beattie, D 2007 - Personal communication
Figure 2: 10 yr genetic trend in number of teats
L02
L03
0.7
Teat number EBV
0.6
0.5
0.4
0.3
0.2
0.1
Quarter
Coates, A 2007 - Personal communication
186
American Association Of Swine Veterinarians, 2008
06
Q3
06
Q1
05
Q3
05
Q1
04
Q3
04
Q1
03
Q3
03
Q1
02
Q3
02
Q1
01
Q3
01
Q1
00
Q3
00
Q1
99
Q3
99
Q1
98
Q3
98
Q1
97
Q3
97
Q1
0
A maximum of 12% of lost weight during the first lactation and a maximum of 8% average in older parity
sows are considered as the limit body weight loss compatible with high performance (Figure ­3).
of reduction in the daily usage of gestation diet from
7.0 lbs per day to 4.5 lbs per day can be translated into
1.0 to 1.1 lbs/day of additional feed intake in farrowing and every additional lb of average feed intake in
farrowing in turn can be translated into 20-22 extra lbs
weaned per sow per ­year.
Feeding protocol for the typical corn/soybean gestation
diet (US gestation diets) requires adjusting the feed
boxes to drop 4.0 lbs per day for fat sows, 4.5 lbs per
day for sows defined as in normal condition, and 6.0
lbs per day for thin sows. Also feed 6 lbs per day for
normal sows during the last 2 weeks of gestation. Under this management, the sows will use 1,450-1,600 lbs
of gestation feed per sow per year (Table 1).6 Farms facing issues of sow mortality, low weaning weights, and
eventually increased weaning to estrus interval should
compares themselves with the mentioned ­target.
Lactation challenge: number/weight of nursed
­piglets
Farrowing managers should know the number of available teats in a farrowing room before the due date and
load sows with a number of piglets according with
the number of functional teats available. Occasionally
(example, start ups) there are not other choices besides
overloading the ­sows.
The goal of any effective gestation feeding program is
to have 85-90% of the gestating sows in “normal’ condition or body score 3 at 4 to 5 weeks of gestation
(in a Body Condition Score System from 1 to 5; between 14 and 16 mm of P2 back ­fat).
Litter size (number and weight of the piglets nursed) is
the major individual factor in the determination of the
milk production. From a production management point
of view, plan to have more than 50% of the sows weaning 11.0 or more piglets, particularly since milk yield is
more than 50% greater when litter size increased from 6
to 12 piglets.10,11 The female is able to react to a higher
milk requirement by eating more feed. Suckled glands
will be larger and more productive in subsequent lactations than un-suckled or poorly suckled glands.1,2 Lower
performance in farrowing can be traced to the practice
In a project to control annualized sow mortality, the
impact of gestational body weight gain control was seen
in terms of reduction of cost of production per weaned
piglet, with no negative effect on the litter weight gain
in farrowing (Figure 4). The annualized sow mortality
effectively was reduced from 13% to 5%. Further, a
thumb rule was derived from that experience: every lb
Figure 3: Predicted body weight change in sows, lbs
573
600
562
540
507
500
518
463
496
463
396
400
419
319
352
300
200
Breeding P1
W
P2
W
P3
Age
W
P4
W
P5
W
P6
Pinilla, J. C, 2007, Unpublished data. C22 Female
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187
Table 1: Gestation diet usage(based on an average daily usage of 4.8 lbs/day)6
Avg. lactation length
Days before farrowing
Lactation days per cycle
Litter per sow per year
Total days on lactation/sow/year
Days on gestation diet
Total gestation usage/sow/year
15
3
18
2.5
45
320
1,536
17
3
20
2.5
50
315
1,512
19
3
22
2.5
55
310
1,488
21
3
24
2.5
60
305
1,464
23
3
26
2.5
65
300
1,440
of loading P1 females with just 9 to 10 piglets in order
to “prevent extensive catabolism.” Current recommendation is to load P1 with 12 strong and heavy piglets and
support that with proper feeding management, cooler
rooms, limited cross fostering, and water availability
(Table ­2).
Additional management to improve the weight, quality
and vigor of the piglets is to dry the piglets off at birth.
This prevents the chilling complex that creates lethargic
piglets causing them not to drink colostrum. Chilling
is worst when farrowing is induced too soon since the
smaller piglets are more ­susceptible.
The most recent and promising tool to produce heavier
litter is to let the sows farrow naturally and/or limit the
use of farrowing induction to risky sows (fat, lame or older
than P5). Data collected from a commercial farm supports that every additional in gestation allow the piglets
to be born weighing 0.15 extra lbs per additional day in
gestation, in the range from 113 to 118 days (Figure 5).
Consequently those heavier piglets at birth have greater
opportunity to vigorously suckle the teats, survive and
gain weight and be weaned at heavier ­weight.
In the same line, there are limited chances to achieve
high milk yields and maximize the piglet weaning
weight if the piglets have diarrhea. Any preventive
measure or treatment will help to keep them drinking
milk, while they stimulate the mammary glands and
gain weight. Measures like vaccines and feed-back 3 to
6 weeks before the due date, a correct disinfection and
drying of the empty rooms and proper age structure of
the breeding groups (no more than 20% of P0, 18% of
P1, 52% of sows from P2 to P5 and no more than 10%
Table 2: Weaning performance in commercial environment responding to management changes (avg.
sow inventory: 6,670) (1050 females)
Year
Avg. TB
Avg. BA
Weaned per sow
PSY
Litter weight at birth, lbs
Litter weight at weaning, lbs
Gained weight, lbs
Avg. weaning age, days
Avg. piglet weaning weight, lbs
Litter weight gain, lbs/day
Avg. daily milk production(*), lbs/d
Total milk production, lbs/lactation
2005
12.1
11.2
9.4
22.0
34.5
119.4
84.9
18.9
12.7
4.5
18
339
2006
13.0
11.9
10.7
25.9
36.6
130.7
94.1
18.0
12.2
5.2
21
376
(*) Assuming 4 lbs of milk per lb of weight ­gain.
188
American Association Of Swine Veterinarians, 2008
2007 (Jan - Aug)
13.4
12.4
11.3
27.4
37.2
139.0
101.8
17.3
12.3
5.9
23
407
Figure 4: Gestation feed usage and litter weaning weight
Litter weight (lbs)
Gestation feed usage (lbs/sow/day)
7.0
150
6.4
6.3
6.5
5.8
Litter weaning weight (lbs)
146
6.1
5.8
5.8
6.0
5.7
5.4
144
5.4
5.4
5.6
5.5
142
4.8
140
5.0
138
4.5
136
Lbs Gestation per Day per Sow
148
4.0
134
3.5
132
3.0
130
Oct-06
Nov-06
Dec-06
Jan-07
Feb-07
Mar-07
Apr-07
May-07
Jun-07
Jul-07
Aug-07
Sep-07
Month
Frith, P and Pinilla, J. C 2007. Unpublished data. 1050 Female
Figure 5: Avg. birth weight and gestation length
4.0
3.6
Birth weight, Lbs
3.5
3.3
3.2
3.0
3.1
3.0
2.6
2.5
2.0
1.5
1.0
113
114
115
116
117
118
Gestation days at birth
Pinilla, J.C and Mickevicius, E 2007. Unpublished data
Birth weight (lbs) = 0.15 x Gestation Length (days) -114.03 (r2 = 0.83)
American Association Of Swine Veterinarians, 2008
189
of P6 and older sows) are able to make a contribution
to wean heavier ­piglets.
Split nursing should be intensively utilized to provide
colostrum for every piglet, particularly in farms with
high number of average born alive. Utilizing a heated
box, split the litter in two halves and then alternate
each one in 60 minute nursing intervals to maximize
colostrum intake. Mark the first 5 piglets in the plastic
box, leaving plenty of room for the other 6-7 piglets to
drink colostrum. Farms where the split-nursing has been
fully implemented have seen increased survivability and
weaning weight, and less variation in weaning ­weights.
Longer ­lactation
PIC’s research has demonstrated that increasing lactation length increases weaning weight. For every additional day in farrowing with their mother, the weaning
weight increases an average of 0.56 lbs/day/piglet,
which in turn is related to a reduction in the age to
market.15,16 The concept of longer lactation has been
successfully challenged in different systems looking for
heavier piglets at weaning. From a catabolic state, after
day 7-10 of lactation, the females achieve nutritional
balance zero and then they are anabolic so they can use
the feed nutrients to produce milk instead of their body
reserves. In general, the current PIC recommendation
for optimal weaning age is not to wean before 20 days
of lactation.
Many modern farms can not absorb additional days of
inventory in farrowing unless some changes are implemented. The first option is to add farrowing spaces to
the system plus a more efficient use of the farrowing
rooms. To easily calculate how many new farrowing
spaces required just multiply the factor 0.007 times the
average sow inventory times the planned extra days of
lactation. A second option could be a reduction in the
breeding target, and consequently in the average sow
inventory, which takes effect no sooner than 16 weeks
after the action is taken, and it is not as cost-effective as
the addition of more farrowing ­spaces16.
Maximize feed intake in farrowing ­house
It is critical to prevent and/or to control situations leading to off feed sows. Proper hygiene measures associated around farrowing, such as room sanitation, a clean
sleeving process, and individual treatment of fever and
lameness are a must.5 To check the availability of fresh,
cool and clean water is a daily duty in farrowing, making sure the sows have a minimum water flow rate of
0.5 gal per ­minute.
190
Recent field data from a commercial system indicates
that a mild restriction for 3 days followed by full feeding from day 4 through the end of lactation resulted
in increased feed intake and reduced body weight loss.
Based on these data, the recommendation for feeding
PIC sows is to scale feed at 4.0, 4.0, and 6.0 lbs per day
for days 0, 1, and 2 of lactation followed by ad-libitum
access to feed. This pattern ensures the maximum average daily feed intake, milk yield, litter weight gain, and
minimum body weight ­loss.13
Some innovations from the traditional hand feeding
systems have been recently established. One such innovation is the use of self feeders. These feeders are
able increase the average daily feed intake by about 7%
compared with hand feeding systems and are less demanding in ­labor.
No feeding protocol or feeder design will work unless
qualified staff gets the sows up two or three times a day
to stimulate them to eat. Other key duties are cleaning the feeders to prevent mold, adjust the heat lamps
height or simply turn them off when needed, check
room ventilation and temperature. Caretakers must be
able to “read” the sow and piglet behavior and make
adjustments to ensure the sows eating enough feed to
wean healthy and heavy piglets. A way to stimulate the
feed intake is to use wet feed, which is easily consumed
by the most of the sows but has to be handled very well
to prevent a drop in the feed intake or feed refusal due
to mold ­development.
Cross-fostering is a common and preferred management tool. This tool provides opportunities to the
smaller piglets in a room to get enough milk to grow,
but in too many situations the staff tends to use the
fostering too much and/or too often. Create the light
litters as soon as possible after all pigs have received
colostrum and before the social order is established
(occurs sometime between the first 12-16 hours of
life). When the equalization by size is made after day
1, the benefits are limited because it is a disruption of
the normal process of nursing, sows get nervous and
mastitis can become a problem. Nurse sows to raise the
fall-behinds can be created from day 4 to 7, moving a
fresh sow from the next younger room. It is important
to limit the fostering to a maximum of 10-15% of the
litters disrupted after day ­4-7 of age.
Conclusions
1. Select gilts with 12 or more functional ­teats.
2. Select the heavier gilts and mate them after they
achieve 300 lbs of live weight and maximum 330 ­lbs.
American Association Of Swine Veterinarians, 2008
3. Limit body weight gain in gestation, particularly
in younger females by limited gestation diet daily
offer (1,450 to 1,600 ­lbs/sow/year).
4. Load sows according to their number of functional
teats. P1 females should be challenged to produce
milk by loading them with 12-14 strong and heavy
piglets at ­birth.
5. Limit the use of farrowing induction to just critical
sows (fat, older than P5 and ­lame).
6. Use split-nursing and limited use of ­cross-fostering.
7. Maximize the feed intake in ­farrowing.
8. Wean piglets 20 days or ­older.
Acknowledgement
To Dr W Peralta, Agrosuper, Rancagua, ­Chile.
References
1. Williams, N. H. and Pinilla, J. C. 2006. Optimum weaning age recommendations for PIC maternal lines. AASV Proceedings: ­77-81.
2. Pinilla, J. C. 2006. Weaning 1 lb per day per sow. The Weaning Age
Effect. PIC Symposium Proceedings, Nashville, ­TN.
3. Aherne, F. X. 2007. Feeding the Lactating Sow. Available: www.gov.
mb.ca/agriculture/livestock/pork/swine/bab10s04html. Accessed
on Aug 10, ­2007.
4. Williams, N.H., Kummer, R, Pinilla, JC, Piva, J and Neill, C. Milk
production and nutritional requirements in modern sows. Abraves,
­2007.
5. Mackenzie, D. D. S. and Revell, D. K. 1998. Genetic influences on
milk quality. IN: The lactating sow. Verstegen, M. W. A, Moughan, P. J.
and Scrama, J. W. ­(editors).
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7. Williams, N.H., Patterson, J. and Foxcroft, G. Non-negotiables of
Gilts Development. Advances in Pork Production (2005) Volume 16:
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8. Newton, E.A. and Mahan, D. C. 1993. Effect of Initial Breeding
Weight and Management System Using a High-Producing Sow Genotype on Resulting Reproductive Performance Over Three Parities. J.
Anim. Sci. 71:1177-1186.
9. King, R. H., Eason, P. J., Smits, R. J., Morley, W. C. and Henman,
D. J. 2003. The response of sows to increased nutrient intake during
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10. King, R.H., Toner, M. S. and Dove, H. 1989. Pattern of milk production in sows. IN: Batterham, E. S. (Ed.). Manipulation of Pig Production II. P 98. Australasian Pig Science Association, ­Attwood.
11. King, R. H. 1991. Nutrition of sows during lactation dependent on
milk yield. Feedstuffs (October ­28)13-15
12. How does suckling status of a sow’s mammary gland during one
lactation impact productivity of the gland during the next lactation?
www.livestock trail.uiuc.edu/porknet/paperCollection. Accessed
on October 17th, ­2007.
13. Kummer, R. 2007. Production Management to Wean the Most of
the Pigs. PIC Symposium Proceedings. Nashville, ­TN.
14. Boyd, R. D., Touchette, K. J., Castro, J. Johnston, M. E., Lee, K.
U. and Han, I. K. 2000. Recent advances in amino acid and energy
nutrition of prolific sows: Review. Asian-Aus. J. Anim. Sci. 13: ­1638.
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E. 2001. Impact of weaning weight on growth rates, feed conversion,
and carcass composition in PIC progeny. PIC USA Tech Memo ­252.
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Dhuyvette, K. C. and Nelssen, J. L. 2005. JSHAP (13): 322- 332.
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