| Abstract |
Animal Welfare 1996, 5: 25-35 |
| Figure 1 | View into a family pen with four nest areas (N1 to N4), two activity areas (Al, A2) and an unsheltered outside yard (Y). The pen includes six feeding stalls (f), four sites with drinkers (d), four piglet nests (p) and two racks (r). For farrowing only half of the floor of the nest areas was covered with straw (s). |
Six days a week manure was pushed manually from the indoor pens
to the outside yards from where it was removed with a tractor.
From June 1992 to March 1993 the distribution of faeces in a family
pen was recorded on 193 occasions. This was done by dividing both
the inside pens and the outside yards into sectors of about 1.2m²
and estimating the percentage of the surface covered with faeces
in each sector.
The sows, the boar and the fattening pigs (older than 10 weeks)
were fed twice a day with liquid food. On average (n = 186 days)
this was composed of 9.3 per cent barley, 3.5 per cent protein
concentrate, 35.5 per cent kitchen refuse, 27.3 per cent whey
and 24.4 per cent added water. The sows and the boar were fed
in individual stalls whereas the fatteners were fed in troughs
along the corridors leading away from the nest areas. At the end
of each corridor there were nipple drinkers. After morning feeding,
the racks in the activity areas were filled with straw, hay or
grass for behavioural enrichment. In addition, some compost-earth
was distributed by the tractor in the outside yards after removal
of the manure.
A few days before farrowing the family pen was power-hosed. Thereafter
the sows were separated in the nest areas by closing the doors
at the end of the corridors. When five sows farrowed at the same
time, one sow was separated in a nest area of a neighbouring family
pen. In the first version of the Family Pen System (Stolba &
Wood-Gush 1984) the heating lamp for the piglets was situated
at the border of the nest area and behind rails. The problem with
this design was that for the first two to three days after the
birth the piglets did not lie under the lamp but close to the
sow's body (Wechsler et al 1991). In the technologically
improved version of the Family Pen System the nest areas were
therefore structured according to the farrowing pen designed by
Schmid (1993). The piglet nest with a heating lamp and a heating
plate on the floor was placed in the centre of the nest area,
next to the nest site of the sow (Figure 1). With this design
the piglets found the heated place within the first day of life.
In order to ensure that the sow chose her nest site next to the
opening of the piglet nest, only half of the floor of the nest
area was covered with straw. During the study all sows built their
nest in this part of the nest area. From June 1991 to July 1993
piglets that died in the Family Pen System were brought to the
Department of Veterinary Pathology at the University of Zürich
to determine if they had been crushed by the sow.
On an average of 14 ± 3 (SD) days after the last sow of
a family group had farrowed, the inside pen was divided into two
parts of equal size. The four to five sows and their litters were
then grouped in the left half of their family pen (with feeding
stalls). They were offered a communal nest by removing the partition
between the two neighbouring nest areas (N1 and N2, Figure 1).
The piglet nests were pushed to the border of this area and a
special piglet area was installed in the corridor next to the
feeding stalls. In this area the piglets had ad libitum
access to solid food until they were 10-weeks-old. On an average
of 8 ± 7 (SD) days after the formation of the family group,
the boar was added to serve the sows during lactation.
As the piglets grew up, space was increased by also giving the
family group access to the right half of their family pen with
a second activity area and two more nest areas (N3 and N4, Figure
1). The fatteners remained with the sows until they were five-months-old.
Then the fatteners had to be removed because the sows were going
to farrow again. The fatteners were kept for an additional four
to eight weeks in the right half of a family pen, the left half
being occupied by a family group which had recently been grouped
after farrowing. When the fatteners reached a weight of 100kg,
they were brought in groups of 6 to 10 to the slaughter-house.
All fatteners were sold to a marketing organization ('Porco fidelio')
specialized in distributing meat of pigs reared in enriched housing
systems. Preventative admixing of antibiotics to the food as well
as teeth clipping and tail docking in piglets were prohibited.
The organization also required that the piglets were suckled for
at least seven weeks. The price of fatteners reared in this way
is about 20 per cent higher than the price of conventionally reared
pigs.
Statistical analysis
Non-parametric statistics (Mann-Whitney U tests, Spearman
rank correlations; Siegel 1956) were used because not all data
were normally distributed. If not indicated otherwise, P-values
are two-tailed. In the agricultural literature, data on the reproductive
performance of sows are usually presented as mean values. Therefore,
mean values and standard deviations (SD) are used in the text
and in the tables.
Results
A total of 878 piglets were born alive in the three family groups
within two and a half years. Data on reproductive performance
of the sows were calculated separately for three time periods
(A, B, C) of 10 to 11 months each (Table 1). This was done to
illustrate the development of the reproductive performance of
the sows during the course of the study. As the study was started
mainly with gilts, parity (the number of litters born per sow)
increased significantly from period A to period B and from B to
C (P < 0.05, Mann-Whitney U Tests). There were,
however, no significant differences in litter size between the
three periods (P > 0. 05, U Tests). On average
(n = 81 litters) 10. 8 ± 2.6 (SD) piglets were born alive,
and 4.6 per cent of all piglets were born dead.
| Table 1 | Reproductive performance of sows in the Family Pen System (period A: June 1991 to March 1992, period B: April 1992 to February 1993, period C: March 1993 to December 1993; average values are given with standard deviations). |
There were major problems with piglet health (oedema disease,
scour) and with crushing at the beginning of the study. From period
A to period B, however, both overall piglet mortality up to day
28 and the percentage of piglets crushed decreased significantly
(P < 0.05, U tests). Consequently, there was
a significant increase in average litter size from period A to
period B (day 28: P < 0.01, day 70: P < 0.01,
fatteners sold: P < 0.01, U tests). Between periods
B and C neither piglet mortality nor litter size differed significantly.
Mortality in fatteners was stable over the three periods and amounted
to 1. 1 per cent of the piglets that had reached the age of 10
weeks.
On average the sows were successfully mated on day 55 ±
24 (SD) after farrowing (n54). Mean cycle length was 170 ±
24 (SD) days, resulting in 2.15 litters per sow per year. Both
in period B and in period C 19.5 piglets were reared per sow per
year. With eight litters (three in period A, two in B and three
in C) there was a delayed start in the milk production of the
sow, and 72.5 per cent of the piglets born alive in these litters
died before they were four-weeks-old. When these litters were
omitted from the analysis, overall mortality up to day 28 dropped
to 13.3 per cent and crushing to 8.6 per cent in periods B and
C combined (n = 48 litters). In this sample 9.7 ± 1.8 (SD)
piglets per litter were reared up to day 28, resulting in a production
of 20.8 piglets per sow per year.
The rearing success of sows of different breeds did not differ
significantly. The analysis included all litters from periods
B and C in which the sows had no problem with milk production
(n = 48). Both Large White sows (n = 14 litters) and Swiss Landrace
sows (n = 23 litters) reared on average 9.7 ± 1.7 (SD)
piglets per litter up to day 28. The remaining 11 litters were
of Large White x Swiss Landrace crossbred sows that had been born
in the Family Pen System. They had an average litter size of 9.6
± 2.4 (SD) piglets on day 28.
Sows that had been raised in the Family Pen System produced 21.4
piglets per year in periods B and C whereas sows that had been
bought from commercial breeders reared 20.1 piglets per year (Table
2). The number of piglets born alive as well as average cycle
length did not differ between these two samples. But overall piglet
mortality up to day 28 was significantly lower in litters of sows
raised in the Family Pen System (P < 0.05, U
test, one-tailed). There was also a tendency that these sows crushed
fewer piglets (P < 0.07, U test, one-tailed). Average
parity was significantly lower in sows raised in the Family Pen
System (P < 0.001, U test). Parity was, however,
not significantly correlated with overall piglet mortality (rs = 0.23, n = 48, P>,0.05)
nor with the percentage of piglets crushed (rs
= 0. 11, n = 48, P > 0.05). The five litters with a
delayed start in the milk production of the sow in periods B and
C were not included in Table 2, but it has to be mentioned that
they were all from sows that had been bought from commercial breeders.
Piglet mortality was not significantly affected by season. In 17 litters born in summer (May to August) in periods B and C, overall piglet mortality up to day 28 was 16.3 per cent compared with 13.0 per cent in 16 litters born in winter (November to February). Litters with a delayed start in the milk production of the sow were not included in this analysis, and litters from sows that had been raised in the Family Pen System were equally distributed between the two samples (eight litters in summer and seven litters in winter).
| Table 2. | Comparison of the reproductive performance of sows bought from commercial breeders and sows raised in the Family Pen System (average values are given with standard deviations). |
In 28 out of 52 cases (53.8%) the sows were successfully served
during the first seven weeks of lactation. If there was no lactational
oestrus in this period (n = 24 cases), the sow was separated from
her litter for a few days and kept in another family pen together
with the boar. As soon as the sow had been served she was returned
to the family group. This artificial weaning was necessary to
keep a stable interval of about six weeks between the farrowing
dates of the three family groups. There were 17 cases in which
pregnant gilts or sows had been bought from commercial breeders,
10 cases in which gilts were raised in the Family Pen System and
two cases in which oestrus was induced by a hormone injection.
On average, sows served during lactation conceived on day 44 ±
18 (SD) and had a cycle length of 159 ± 19 (SD) days (2.3
litters per year), whereas sows served after artificial weaning
conceived on day 67 ± 25 (SD) and had a cycle length of
183 ± 25 (SD) days (2.0 litters per year). There was no
significant difference in the number of piglets born per litter
depending on whether the sows had been served in lactational oestrus
or after weaning. Sows that conceived during lactation regularly
suckled their piglets until these were 12-weeks-old. At 14 weeks
most litters were not suckled any more, but one litter was only
weaned when the piglets were 18-weeks-old.
In most cases either all sows of a family group or none were served
during lactation, and farrowing dates were well synchronized in
the group (within two weeks). Only on six occasions a sow had
to be transferred to another family group, as her farrowing date
was more than three weeks later than the dates of the other sows
in her group. These group changes were inevitable, because cross-suckling
of the piglets can become a major problem if age varies too much
between litters. The introduction of a sow into another family
group did not result in excessive aggressive behaviour, as the
family pens were well structured. This enabled the new sow to
withdraw from the other group members after some initial fights.
Gilts were selected from the fattener groups. The selection was
based on the growth and the physique of the gilt as well as on
the reproductive performance of her mother. Nine out of ten gilts
were reintroduced to the family group in which they had been reared.
This was done when the sows and their litters were grouped two
weeks after farrowing. Although the gilts had been separated from
their family group for 31 to 69 days, the sows and the gilts obviously
recognized each other, as there were no fights. The gilts were
then served for the first time (on average 203 ± 21 (SD)
days old) together with the sows of their family group.
The fattening period started when the pigs were 70-days-old (weight
about 25kg) and ended when they were about 170-days-old (weight
100kg).In two groups of fatteners (n = 40 and 26 animals) from
two different family groups, average daily weight gains of 751
g and 803g, respectively, were computed for this period. A total
of 264 fatteners per year were produced in the three family groups.
In the first 12 litters (four in each family group) at the
beginning of the study, suckling behaviour was observed in detail.
All piglets were marked individually and the presence of cross-sucklers
was recorded in a total of 1866 nursing bouts from week two to
week eight after farrowing. Only 10 out of 89 piglets (11. 2%)
gave up the teat on their mother's udder and, after a few days,
suckled with another sow. Interestingly, all these piglets changed
to the sow with the least number of piglets in her family group.
For 16 days, time required to prepare and distribute the food
(twice a day) as well as to remove the manure from the three family
pens was measured. On average, labour input was 18min day-1 for preparing the soup, 23min
day-1 for feeding the sows and
the growing pigs, 28min day-1
for cleaning the inside pens and 9min day-1
for removing the manure from the outside yards with a tractor.
As can be seen in Figure 2, the pigs defaecated mainly in the
outside yards and, to a lesser extent, in the activity areas of
the inside pens.
| Figure 2. | Distribution of faeces in the family pen. The shadings indicate the ave- rage percentage of each sector's surface that was covered with faeces (white: 0 to 10%, light grey: I I to 50%, dark grey: 51 to 100%). |
Discussion
In the second and third period of the study the sows had a stable
performance of 19.5 piglets (28-days-old) reared per year in the
new version of the Family Pen System. For a comparison, Large
White and Swiss Landrace sows kept in conventional housing systems
rear on average 21.5 and 20.7 piglets per year, respectively (data
published by the union of breeders in Switzerland, Kleinviehzucht
1993). The fact that the sows that had been raised in the Family
Pen System reared on average 21.7 piglets per year shows that
the reproductive performance of the sows can reach the level of
conventional housing systems.
Although all piglets were suckled for at least seven weeks, mean
cycle length was only 170 days. This is just one week longer than
average cycle length in sows of Swiss breeds whose litters are
usually weaned at the age of four to five weeks (Large White:
163 days, Swiss Landrace: 164 days; Kleinviehzucht 1993). The
combination of a long suckling period and a relatively short cycle
length was possible because 53.8 per cent of the sows were served
within the first seven weeks of lactation. The incidence of lactational
oestrus was, however, lower than in the original version of the
Family Pen System where 81.9 per cent of the sows were served
during the first seven weeks of lactation (Kerr et al 1988).
In the present study the sows conceived also later in lactation
(on average on day 44) than in the original version of the Family
Pen System (day 33, Kerr et al 1988). The difference in
the occurrence of lactational oestrus is possibly due to the poorer
quality of the food given to the sows. On the commercial farm
a ration containing 35 per cent kitchen refuse of variable energy
content was used whereas in the study of Kerr et al (1988)
the sows were fed with pellets.
In order to reduce piglet mortality the nest areas were structured
in a new way for farrowing. In the first period of the study overall
mortality up to day 70 was extraordinarily high (35.7%), dropping
to 22.8 per cent and 20.1 per cent in the second and third period,
respectively. These percentages are very similar to the mortality
in the original version of the Family Pen System where 21.9 per
cent of all piglets born alive died within the first 10 weeks
(Kerr et al 1988). Especially for crushing (13.8% and 9.2%
in the second and third period of the study, respectively) better
results had been expected, as the nest areas were structured in
the same way as the farrowing pen designed by Schmid (1993) in
which only 5.5 per cent of the piglets were crushed.
Piglet mortality was significantly lower in sows that had been
raised in the Family Pen System compared to sows that had been
bought from commercial breeders, and the former sows also tended
to crush fewer piglets (only 5.8 %). Their good performance can,
however, not merely be attributed to the housing conditions during
their ontogeny, as daughters of sows with low rates in mortality
and crushing were, of course, preferentially selected as replacement
gilts. It is also possible that the home-bred sows were better
adapted to the disease profile present on the farm and that they
passed their immunity to the piglets. Nevertheless, the results
indicate that the productivity of the Family Pen System can be
improved by creating a breeding stock that is (probably both genetically
and ontogenetically) adapted to these housing conditions.
The management of pigs kept in family groups is much different
from the management of tethered sows or fatteners kept in small
groups. But there is also a routine that is repeated in each reproductive
cycle of a family group and it caused no organizational problems
to run three family groups in parallel on the commercial farm.
Artificial weaning after seven weeks without lactational oestrus
was found to be a practicable solution to achieve a constant interval
of about six weeks between the farrowing dates of the three family
groups. In addition, it was sometimes necessary to transfer a
sow to another family group, i f she had conceived more than three
weeks later than the rest of the sows of her group. Both types
of intervention are not optimal with respect to the pigs' welfare,
but in some cases inevitable for a continuous production of fatteners.
It was an aim of the present study to improve the original version
of the Family Pen System with regard to time required to feed
the pigs. Kerr et al (1988) described an advanced version
of the Family Pen System with individual sow feeding stalls and
ad libitum feed hoppers for the growing pigs. They measured
a mean of 14.3min day-1 required
to feed all pigs of one family group. In the present study there
were also feeding stalls for the sows, but the growing pigs were
fed twice a day with liquid food. Time required to feed all pigs
of one family group was, however, almost identical (13.9min day-1).
Time required for daily cleaning of the family pens is reduced
if the pigs concentrate their eliminative behaviour to dunging
sites that are situated in the front of the stable. With the technologically
improved version described here, this was achieved by adding outside
yards to the indoor pens. In a previous study Mollet and Wechsler
(1991) had found that pigs have a preference for dunging sites
in which they can have contact with conspecifics in a neighbouring
pen. The gates between the outside yards of the three family pens
were therefore filled with lattice. As expected, the sectors close
to these gates turned out to be very attractive dunging sites.
Animal welfare implications
The study has shown that the Family Pen System is practicable
on a commercial farm and that it is feasible to rear piglets and
fatteners in species-specific family groups. Artificial weaning
is not necessary at all with half of the litters, as the sows
can be served in lactational oestrus. With the other half of the
litters artificial weaning can be delayed until the piglets are
seven-weeks-old and their separation from the sow has to last
but a few days. In addition, it is possible to keep the sows in
groups of closely related animals by integrating gilts into the
family group in which they were reared.
In the technologically improved version of the Family Pen System,
pigs are kept in a complex and enriched environment. The family
pens are well structured and divided into several areas. Within
these areas the pigs find different environmental qualities that
elicit different types of behaviour. When moving around the pen,
they meet variably composed subgroups of their family group. These
features contrast much with the standard rearing conditions of
piglets and fatteners kept in small groups and in largely unstructured
pens. In conclusion, the Family Pen System not only enables the
pigs to live in species-specific family groups, but also offers
them a physical environment of high quality.
© 1996 Universities Federation for Animal Welfare
This article originally appeared
in Animal Welfare 1996, 5: 25-35
Reprinted with permission of the editor.
Animal Welfare web site: http://www.users.dircon.co.uk/~ufaw3/animalwelfare.htm