When All-In/All-Out is not ‘AIAO’: a technical note on its consequences for pig health

Abstract

The objective of this study was to track animal movements in a farrow-to-finish commercial pig farm with self-declared AIAO management and to investigate possible associations with animal health. A batch of 1,050 pigs born within one week were individually tagged at birth and followed to slaughter. Management on this farm after weaning at 28d included nursery, growing and finishing stages of 8, 4 and 8 weeks, respectively. Animal management was as per usual practice in the farm and weekly movement of animals was tracked. Pigs were initially allocated to 17 pens. Four weeks post-weaning, tagged pigs were found in 29 different pens. It took 5 extra weeks than planned to clear the nursery of tagged pigs. By 9 weeks post-weaning, there were 8 pens of tagged pigs in the nursery, 25 pens in the grower and 22 pens in the finisher houses. All animals were slaughtered within 1 week at approximately 20 weeks post-weaning and were retrospectively classified into three production flows (F) according to the time spent in each stage (F1 = normal, F2 = delayed 1 week and F3 = delayed >1 week). Tail lesions (TL), pleurisy, enzootic pneumonia lesions (EP), pericarditis and heart condemnations were recorded at slaughter and analysed using logistic regression. There was no difference between flows in the likelihood of TL or EP (P > 0.05). Pigs in F2 were 2.86 times at greater risk of pericarditis and 2.82 times at greater risk of lameness compared with pigs in F1 (P < 0.05). Similar results were observed between F3 and F1 pigs (P < 0.10). The failure to, inadvertently, adhere to the stated AIAO policy of this farm was associated with negative consequences for the health of the animals

Full text

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When All-In/All-
health
J.A. Calderón Díaz1, 2, L.A. Boyle1, A. Diana1, 3, M. McElroy4, S. McGettrick4, J. Moriarty4 E.G.
Manzanilla1
1Pig Development, Teagasc Moorepark Grassland Research and Innovation Centre, Fermoy, Co. Cork,
Ireland
2Department of Animal Behaviour and Welfare, Institute of Genetics and Animal Breeding, Polish
-552 Magdalenka, Poland
3School of Veterinary Medicine, University College Dublin, Dublin, Ireland
4Central Veterinary Research Laboratory, Department of Agriculture, Food and the Marine
Laboratories, Backweston, Celbridge, Co. Kildare, Ireland
SUMMARY: The objective of this study was to track animal movements in a farrow-to-finish
commercial pig farm with self-declared AIAO management and to investigate possible associations
with animal health. A batch of 1,050 pigs born within one week were individually tagged at birth and
followed to slaughter. Management on this farm after weaning at 28d included nursery, growing and
finishing stages of 8, 4 and 8 weeks, respectively. Animal management was as per usual practice in the
farm and weekly movement of animals was tracked. Pigs were initially allocated to 17 pens. Four
weeks post-weaning, tagged pigs were found in 29 different pens. It took 5 extra weeks than planned to
clear the nursery of tagged pigs. By 9 weeks post-weaning, there were 8 pens of tagged pigs in the
nursery, 25 pens in the grower and 22 pens in the finisher houses. All animals were slaughtered within
1 week at approximately 20 weeks post-weaning and were retrospectively classified into three
production flows (F) according to the time spent in each stage (F1 = normal, F2 = delayed 1 week and
F3 = delayed >1 week). Tail lesions (TL), pleurisy, enzootic pneumonia lesions (EP), pericarditis and
heart condemnations were recorded at slaughter and analysed using logistic regression. There was no
difference between flows in the likelihood of TL or EP (P > 0.05). Pigs in F2 were 2.86 times at greater
risk of pericarditis and 2.82 times at greater risk of lameness compared with pigs in F1 (P < 0.05).
Similar results were observed between F3 and F1 pigs (P < 0.10). The failure to, inadvertently, adhere
to the stated AIAO policy of this farm was associated with negative consequences for the health of the
animals -
Key words: All-in/all-out, pig health, production flow
INTRODUCTION
All-In/All-Out (AIAO) production has several advantages for pig production systems such as reduced
disease transmission and improved management and growth performance (Scheidt, et al., 1995; Owsley
et al., 2013). In a true AIAO system, groups are move together to the next production stage so that the
facility is completely emptied before the next group arrives. This however, represents a challenge for
the management of slow growing pigs. In an AIAO system, slow growing pigs should only be allowed
to accumulate off-site (Owsley et al., 2013) but this might not happen in practice. To our knowledge,
there is limited information regarding the management of slow growing pigs in commercial farm that
declare to follow an AIAO production system and its possible implications on pig health. Therefore,

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the objective of this study was to track animal movements in a farrow-to-finish commercial pig farm
with self-declared AIAO management and to investigate possible associations with animal health.
MATERIAL AND METHODS
The study received ethical approval from the Teagasc Animal Ethics Committee (TAEC 40/2013). The
study was conducted on a 1,500 sow farrow-to-finish commercial farm in Co. Limerick, Ireland. A
total of 1,050 pigs born within one week were individually tagged at birth and followed to slaughter.
Gender, number of piglets born alive, sow parity, number of times each piglet was cross-fostered and
lactation length were recorded. Management on this farm after weaning at 28d included nursery,
growing and finishing stages of 8, 4 and 8 weeks, respectively. Animal management was done as per
usual practice in the farm (for more details please refer to Calderón Díaz et al.; submmitted) and the
weekly movement of animals was tracked. Pigs were initially allocated to 17 pens (Figure 1a). Four
weeks post-weaning, tagged pigs were found in 29 different pens (Figure 1b) in different rooms of the
nursery. It took 5 extra weeks than planned to clear the nursery of tagged pigs. By 9 weeks post-
weaning, there were 8 pens with tagged pigs in the nursery, 25 pens in the grower and 22 pens in the
finisher houses (Figure 1c). In total, it took 15 weeks post-weaning to move all the pigs into the finisher
stage.
Figure 1. Layout of the pig facilities on a commercial farm with self-declared AIAO management.
Pens in yellow
post- -weaning.
Eight-hundred-and-twenty-four pigs reached slaughter age/weight and they were slaughtered within 1
week at approximately 20 weeks post-weaning. Pigs were retrospectively classified into three
Nursery stage
Weaning
(week 1)
a)
4 weeks
post-weaning
b)
Nursery stage
9 weeks post-weaning
Nursery stage
Building 1 Nursery stage
Building 2 Grower stage
Finisher stage
c)

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production flows according to the extra time they required to be moved to the next production stage
[i.e. flow 1 = normal (n =620 pigs), flow 2 = delayed 1 week (n = 111 pigs) and flow 3 = delayed >1
week (n = 93)]. Prior to slaughter, pigs were scored for lameness by a single trained observer on a 3-
point scale where 1 = non lame; 2 = mildly lame and 3 = severely lame. At slaughter, tail lesions were
scored after scalding and dehairing by one trained observed as per Harley et al. (2012). Pleurisy was
scored using the Slaughterhouse Pleurisy Evaluation System (SPES; Dottori et al., 2007) and Enzootic
pneumonia (EP) like lesions were scored according to the BPEX Pig Health Scheme (BPHS; 2016) by
a trained observer. Additionally, presence or absent of pericarditis and where organs such as the heart
and liver were condemned was also recorded.
Statistical analysis. Each pig was considered as the experimental unit. As only one pig was scored as
severely lame, lameness was classified as non-lame and lame. Only 15 pigs had their liver condemned,
therefore, liver condemnations were not analysed. Tail lesions, pleurisy and EP were re-classified as
present or absent. Univariable logistic regression models (PROC GENMOD; SAS Inst. Inc., Cary,
NC), with flow as predictor variable, were used to investigate the relationship between flow and the
recorded variables. Alpha level for determination of significance and trends were 0.05 and 0.10,
respectively.
RESULTS
Table 1 shows the odds ratios for the likelihood of presenting the lameness, tail lesions, pleurisy, EP,
pericarditis and heart condemnations by flow. Pigs in flow 2 had at greater risk of lameness and
pericarditis compared with pigs in flow 1 (P < 0.05). Pigs in flow 3 had a greater risk of lameness,
pleurisy, pericarditis and heart condemnations compared with pigs in flow 1 (P < 0.05). Additionally,
pigs in flow 3 had a greater risk of pleurisy and tended to have a greater risk of heart condemnations
compared with pigs in flow 2 (P < 0.05).
Table 1. Univariable logistic regression models of the risk in three different production flows1
associated with lameness prior to slaughter, tail lesions, pleurisy, enzootic pneumonia (EP), pericarditis
and heart condemnations in 854 finisher pigs followed from birth to slaughter in a commercial farm
with self-declared AIAO management.
Flow 1 vs Flow 2
Flow 1 vs Flow 3
Flow 2 vs. Flow 3
95% CI3
95% CI
95% CI
Health conditions OR2 Lower
Upper
OR Lower
Upper
OR Lower
Upper
Lameness4 2.82a
1.73 4.58
3.74a
2.27 6.18
1.33 0.72 2.43
Tail lesions5 0.98 0.64 1.51
0.69 0.44 1.08
0.7 0.4 1.24
Pleurisy6 1.34 0.82 2.17
3.31a
2.08 5.27
2.48a 1.35 4.56
Enzootic Pneumonia7 1.16 0.77 1.74
1.21 0.77 1.89
1.04 0.6 1.83
Pericarditis 2.86a
1.54 5.29
4.97a
2.77 8.92
1.74 0.86 3.53
Heart condemnations 1.60 0.84 3.08
3.18a
1.77 5.73
1.98(a)
0.92 4.28
1All animals were slaughtered within 1 week at approximately 20 weeks post-weaning and were retrospectively classified
into three production flows according to the extra time they required to be moved to the next production stage (i.e. flow 1 =
normal, flow 2 = delayed 1 week and flow 3 = delayed >1 week); 2 Odds ratios; 395% confidence interval
4Scored prior to slaughter on a 3-point scale were 1 = non lame; 2 = mildly lame and 3 = severely lame; 5Scored after
scalding and dehairing by one trained observed as per Harley et al. (2012); 6Scored using the Slaughterhouse Pleurisy
Evaluation System (SPES; Dottori et al., 2007); 7Scored according to the BPEX Pig Health Scheme (BPHS; 2016).

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DISCUSSION
The farm where this study was conducted did not follow an AIAO production system but the farmer
and personnel were not aware about it. This problem has been observed by our team in many other
farms. Many factors such as staff rotation, disease outbreaks or economic decisions might influence the
adherence to an AIAO policy. The production system followed in this particular farm more resembled a
continuous flow rather than an AIAO system. Rooms and /or pens did not have any sort of
identification (i.e. age group, weaning date, date on arrival to that particular stage, etc.) making the
adherence to the AIAO policy more challenging. By anecdotal accounts, in this particular farm, some
staff thought that the smaller pigs were in fact younger pigs and thus, they had to stay for some extra
time in that particular stage. Others thought that retaining slow growing pigs for longer periods of time
in each stage would allow them to catch up and reach adequate slaughter weights. However, as noted
by Owsley et al. (2013), slow growing pigs are usually affected by disease, are less efficient to convert
feed into weight gain and may never reach an acceptable slaughter weight. In this study, pigs that did
not follow the normal production flow were at greater risk of diseases supporting the theory that
delaying pigs in the different production stages is associated with re-circulation of disease. For
instance, lung infection could act as a port of entry of colonization of mycoplasmas (especially M.
Hyopneumoniae) of the pericardium (Coelho et al., 2014) and pericarditis has been reported as one of
the reasons for carcass condemnations in slow growing pigs (Martínez et al., 2007). Nonetheless,
further analysis is needed to elucidate whether the greater risk of diseases in delayed pigs are causative
or explanatory. For example, it is possible that lame animals were delayed to allow them to recover but
it is also likely that animals that were delayed were also remixed several times increasing the likelihood
of lameness (Spoolder et al., 2009).
In conclusion, the failure to, inadvertently, adhere to the stated AIAO policy of this farm was
associated with negative consequences for . It is possible that farm staff is not completely
clear in what an AIAO encompasses and thus, it is important to develop teaching methods (i.e.
workshops, discussion groups, newsletters, etc.) that would help to clarify the AIAO policy and to
identify the best practices to implement it on farm. -
from stage to stage but rather use a split marketing approach when sending pigs to slaughter) might be
more easily adhered to on Irish pig farms.
ACKNOWLEDGMENTS
This project was supported by the Irish Department of Agriculture, Food and the Marine (DAFM) grant
14/S/832.
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