Impact of improved hygiene: Farrowing accommodation and liquid feeding systems

There are many factors associated with internal biosecurity and the impact of proper implementation of individual measures such as cleaning and disinfection routines is not always clear or evident. Implementing cleaning and disinfection routines correctly takes time.

Summary

Measures taken to increase internal biosecurity in pig production have previously been shown to increase pig growth, reduce mortality (Laanen et al., 2013) and reduce antibiotic usage (Postma et al., 2017).  However, there are many factors associated with internal biosecurity and the impact of proper implementation of individual measures such as cleaning and disinfection routines is not always clear or evident.  Furthermore, implementing cleaning and disinfection routines correctly takes time and there is always the temptation to take short cuts or, in the worst case, avoid altogether, particularly where labour and space on a pig unit are limited.  Here we look at the importance of hygiene routines in two very different but critically important areas on the unit; farrowing accommodation and liquid feeding systems.

Our work shows that implementing an effective hygiene routine (optimised cleaning and disinfection) in farrowing accommodation reduced the number of clinical cases recorded per litter, leading to a reduction in the volume of antibiotics and anti-inflammatories that needed to be administered to piglets up to weaning.  As a consequence of this, average piglet weight at weaning was also significantly increased.

Cleaning and disinfection routines are seldom, if ever, performed on liquid feeding systems.  However, we know that feed efficiency is poorer for liquid-fed than dry-fed pigs (at least by 0.10 of an FCE unit; O’Meara et al., 2020) and much of this difference is believed to be due to the loss of energy and amino acids from liquid feed due to microbial fermentation.  The feeding equipment itself, which includes the mixing tanks and feed pipelines, contains biofilms that harbour bacteria and fungi which can contaminate the feed, thereby increasing fermentation losses.  Although it did not completely remove the biofilm present, the hygiene routine implemented on the feeding system between batches of pigs, greatly disrupted it and reduced E. coli, Enterobacteriaceae and mould counts to below detectable levels in swabs from the inside of pipelines.   However, this improved hygiene of the mixing tank and pipes did not improve the microbial quality of the liquid feed, most likely due to the high microbial load within the feed itself.  Nonetheless, the improvement in system hygiene now provides us with the opportunity to improve feed quality through dietary acidification or even by introduction of beneficial microbes (e.g. homofermentative inoculants; produce only lactic acid as an end product of fermentation) to the feeding system/feed so that they dominate the microbial populations within the feeding system.

Farrowing Accommodation Hygiene

Introduction

There is concern that high use of antibiotics in pig production can promote the spread of antibiotic resistance (AMR) from animals to humans.  Hence, the current drive to reduce on-farm antibiotic usage. Furthermore, therapeutic levels of in-feed zinc oxide have been banned in the EU since June 2022. A multifaceted approach will now be required to maintain post-weaning piglet health and growth. We believe that implementing an optimised cleaning and disinfection routine in farrowing rooms to provide a hygienic environment for piglets to be born into, should be part of that strategy.

Study

As part of the PigNutriStrat project we recently tested an optimal cleaning and disinfection routine and compared it with a sub-optimal routine.

The optimal routine was as follows:

1. Pre-soaking of pens with water overnight (18 hr).
2. Detergent application (Blast Off; Biolink Ltd, Hull, UK) with a contact time of 20 min. Thorough washing of pens with cold water. Pens allowed to dry overnight, with a blow heater used to speed up the process.
3. Application of a chlorocresol-based disinfectant (Interkokask®; Interhygiene GmbH, Cuxhaven, Germany).
4. Pens allowed to dry for 6 days (note that 3 days drying produces equivalent results), with a blow heater used for the first 24 hr.
5. Sows were washed with cold water and disinfected (Virkon S; Lanxess, Köln, Germany) before they entered the farrowing crates.

The sub-optimal routine consisted of:

1. Thoroughly washing pens with cold water and allowing pens to dry overnight (≤18 hr) before introducing sows.
2. Sows were not washed or disinfected before entering the farrowing crates.

To determine the efficacy of the optimal cleaning and disinfection routine we took swabs from various locations in the farrowing pens. From these, we obtained total bacterial counts and Enterobacteriaeace counts per cm² of each area swabbed.  Enterobacteriaeace are a group of bacteria that act as indicators of faecal contamination. An example of the results obtained can be seen in Figure 1, where total bacterial counts are displayed for the floor area behind the sow before washing and again at entry of the sows to the farrowing pens. It can be seen that after using the optimal cleaning and disinfection routine, the total bacterial count decreased by more than 400,000-fold in this area of the pen, while it decreased only ~30-fold using the sub-optimal regime. This trend was consistently observed for each area of the pen swabbed, both for total bacterial and Enterobacteriaeace counts.

Figure 1. Total bacterial counts on the floor area behind the sow in Log CFU/cm²   

¹ Detection limit before washing (1.4 Log CFU/cm²).  ² Detection limit after washing (0.4 Log CFU/cm²)

As a result of implementing the optimised cleaning and disinfection routine in the farrowing rooms we found that the number of clinical cases per litter was reduced by 86% (Figure 2).

Figure 2. Effect of the optimal cleaning and disinfection routine on the number of clinical cases recorded per litter.

Figure 3. Effect of the optimal cleaning and disinfection routine on antibiotic usage in mL/litter

As a result of this, the volume of antibiotics and anti-inflammatories administered per litter was reduced by 77% and 75%, respectively (Figure 3 and Figure 4)

Figure 4. Effect of the optimal cleaning and disinfection routine on anti-inflammatory usage in mL/litter

Not only did the optimised cleaning and disinfection routine reduce the need to use antibiotics and anti-inflammatories, it also increased piglet weaning weight. Pigs were weaned at ~28 days and on average piglets were 320g heavier at weaning for the optimised cleaning and disinfection routine (Figure 5).

Figure 5. Effect of the optimal cleaning and disinfection routine on weaning weight (Kg)

In summary, implementing the optimised cleaning and disinfection routine described above reduced the number of clinical cases recorded per litter, leading to a reduction in the volume of antibiotics and anti-inflammatories that needed to be administered per litter.  As a consequence, piglet weaning weight was also significantly increased.

Implications

It might be considered that the sub-optimal hygiene routine implemented here was quite basic. However, when compared with the routine on the Moorepark unit, at the time, it yielded similar numbers for clinical cases and volume of antibiotics and anti-inflammatories administered per litter.  Therefore, we believe it to be a good representation of the effect of current on-farm hygiene routines.  Implementation of the optimised cleaning and disinfection routine certainly takes more labour, but particularly more time.  Implementing it will necessitate there being sufficient accommodation to allow it to be implemented correctly. However, the results speak for themselves with regard to its potential to reduce antibiotic use and its benefit in increasing piglet weaning weight.

Liquid Feeding System Hygiene

Introduction

There is no standard protocol for maintenance of liquid feeding system hygiene.  This is despite the fact that poor hygiene in these systems is linked with the growth of undesirable bacteria and fungi (yeasts and moulds) that reduce the nutritional quality of the feed and may even be pathogenic.  Feed conversion efficiency is at least 0.1 of an FCE unit poorer with liquid feeding compared to dry feeding (O’Meara et al, 2020) and much of this difference is thought to be due to losses of amino acids and energy from the liquid feed as it is fermented by microbes in the feeding system.  As a first step towards improving feed efficiency in liquid-fed finisher pigs we performed a study to determine the effect of introducing an effective sanitisation programme on the hygiene of the liquid feeding system itself, as well as and on the microbial quality of the liquid feed. 

Study

As part of the WetFeed-2 project we recently tested an optimal hygiene routine for liquid feeding systems and compared the resultant microbial counts (mixing tank, pipelines and feed) during a 10-week grow-finisher feeding study with those obtained before the routine was implemented and before the batch of pigs was introduced.

The optimal routine was as follows:

1. Remove pigs and wash pens and troughs.
2. Intensive washing and scrubbing of mixing tank and rinse.
3. Alkali wash (Avalksan Gold Standard CF Chlorine Free at 0.9 % inclusion) of tank with circulation of pipeline for 10 min every 2 hr for 16 hr. Feed out to troughs. Rinse tank with water and feed out to troughs.
4. Initial acid rinse (Interpronutri Plus BE [Formic (60%), Propionic (15%) and Benzoic (2.5%) at 6 L/T of water inclusion] with circulation of pipeline for 10 min every hour for 4 hr. Feed out to troughs and wash troughs.
5. Daily Maintenance acid rinse of tank and pipes with Interpronutri Plus BE (3 L/T of water inclusion) with circulation of pipeline for 10 min every hour for 6 hr at night. Rinse residue makes up part of wet mix in first feed split of each day.
6. Introduce new batch of pigs.
7. Continue maintenance rinse of tank and pipes with Interpronutri Plus BE as above daily for 10 weeks.

To determine the efficacy of this sanitisation routine we took baseline samples before the previous batch of pigs were sold prior to starting the hygiene protocol. Following this, samples were taken at day 1, 3 and 7 post-cleaning as well as every week thereafter until the end of the study at 10 weeks when pigs were sold.  Samples of feed were taken from the mixing tank and troughs (fresh and residual from the latter) for microbiology, as well as ATP, pH and temperature measurements and chemical analysis.  Additionally, swabs were taken from the mixing tank and inside the pipeline for microbiological analysis and from the pipeline for microscopy.

Figure 6. Effect of the feeding system hygiene routine on ATP levels and microbial counts on mixing tank surface

Initially post-cleaning, Enterobacteriaceae and yeast and mould counts on the mixing tank surface declined to become undetectable. However, ~5 weeks post-cleaning counts began to return to levels found at the baseline sampling point (Figure 6).  Readings obtained from the ATP luminometer provide information on total surface contamination (from microbes, feed and faeces) and these mirrored very closely the microbial counts. This is a method that could be easily used on commercial units to obtain immediate results regarding the efficacy of sanitisation of surfaces after hygiene protocols have been implemented.

Figure 7. Effect of the feeding system hygiene routine on ATP levels and microbial counts on pipeline surface

Similarly, although microscopy demonstrated that the hygiene routine implemented did not completely remove the biofilm present on the internal surface of the pipelines between batches of pigs, it greatly disrupted it and reduced E. coli, Enterobacteraceae, and mould counts to below detectable levels in the pipelines (Figure 7).  

Microbial counts in feed samples were similar to those obtained at baseline at all sampling time points during the study, indicating that the hygiene routine used alone did not impact feed microbial quality.

Implications

The improved hygiene of the mixing tank and pipes did not on its own improve the microbial quality of the liquid feed, most likely due to the high microbial load in the feed itself.  However, the improvement in system hygiene (particularly in the pipelines) now provides us with the opportunity to improve feed microbial quality through dietary acidification or even by introduction of beneficial microbes (e.g. homofermentative inoculants) to the feeding system/feed so that they dominate the microbial populations within the feeding system.  Improved hygiene of the system reduces the risk that feed and water introduced to the system will be seeded with potentially harmful spoilage/pathogenic microbes from the system itself.

Acknowledgements

The PigNutriStrat project is funded by the Irish Department of Agriculture, Food and the Marine’s Competitive Research Funding Programmes (Grant no: 2019R518).

The WetFeed-2 project is funded by Teagasc Core funding (RMIS no: 1159). James Cullen is supported by the Irish Research Council Government of Ireland Postgraduate Scholarship. Florence Viard’s PhD is supported by a Teagasc Walsh Scholarship. Thanks to Interchem Ltd. (Colum Killeen and Lisa Hopkins), Irish Dairy Services (Gerard Kellett and David Mulhall), Annona (Hans Jensema), Big Dutchman (Dennis Engelking) for their invaluable input to the study presented.

Thanks also to staff and students in the pig unit at Moorepark for assistance in performing both of the studies reported here.