Producers spend a great deal of time and effort caring for and assisting newly weaned pigs to get off to a good start post-weaning. While closing out a successful nursery group can involved many areas, this paper will detail some of the critical factors associated with 1) feed intake; 2) feeder management; and 3) hygiene practices.

Management to Encourage Feed Intake

Numerous management procedures are critical to maximising feed (energy) intake and improving performance in the nursery. The factors necessary to maximise feed intake include a warm draught-free environment and an overall herd health programme and pig flow that minimises exposure to antigens.

Providing easily accessible drinking water fixtures and unlimited water supply is essential. An often overlooked, but critical need is a dedicated workforce who can identify the signs of a "starve out-" pig and can then gently "teach" the pig where and how to eat with either mat or individual feeding¹.

Conditions to identify “starve-out” pigs

• Mental status – alert or depressed
• Body condition – normal or thin
• Abdominal shape – round or gaunt
• Skin – sleek appearance versus fuzzy
• Appetite – feeding at the feeder or huddled
• Signs of dehydration – normal or sunken eyes

Some pigs simply do not start eating readily after weaning. Teaching these “starve-out” pigs to eat, rather than treating them with an antibiotic will save more pigs.

Lastly, one of the most important factors in maximising feed intake is allowing ad libitum access to feed. Many times when pigs exhibit post-weaning diarrhoea or loose stools, producers will begin to limit-feed pigs, thinking that this will minimise the severity of the post weaning scours. However, failure to investigate causative agents like improper air temperature or ventilation, poor sanitation, or inappropriate ingredient selection or quality can lead to failure to solve the primary problem. Limit feeding in the nursery results in reduced nursery exit weights. This is demonstrated by the exit weight of nursery groups in a large production system (Figure 1). Exit weights typically averaged 40 to 48 lb when nursery managers limit-fed pigs the initial week after weaning. However, when management switched to ad libitum feeding by always having feed present in the trough throughout the entire nursery phase (8 weeks), feed intake and exit weights increased dramatically.

Figure 1. Changes in nursery exit weight and feed intake as a result of switching from limited- to ad libitum nursery feed intake

Feeder Management

Proper and frequent feeder adjustment is the key to excellent feed efficiency and low feed cost in the nursery. Proper feeder adjustment starts with the first additions of feed to the feeder. Regardless of whether the first diet after weaning is in bags or bulk, the feed gate in all feeders should be closed before the first pellets are placed in them. The feed gate then should be opened so that a small amount of feed is visible in the feed pan. Placing pelleted feed into an empty feeder with the agitation gate open will result in large amounts of feed filling the trough, leading to feed wastage and difficulty in achieving the proper feeder adjustment.

Although adequate amounts of feed must be present in the feeder at all times after weaning, too much feed present in the pan of the feeder also can decrease growth rate. In an attempt to stimulate feeding behaviour, some producers place large amounts of the first diet in the feeding pan. Although the intention is correct, the outcome is negative. Energy deficiency can result from pigs “sorting” the diet and a build-up of fines in the feeding pan. These fines then lodge in the feed agitator mechanism, making it difficult for new feed to flow from the feeder. This problem can be corrected by managing the amount of feed flow in the pan to stimulate development of feeding behaviour.

Approximately 50 per cent of the feeding pan should be visible in the first few days after weaning. As the pigs become more accustomed to the location of the feed and adjust feeding behaviour, the amount of the feed in the feeding pan should be decreased rapidly to less than 25 per cent coverage. Also, feed agitators need to be tested frequently to ensure that the build-up of fines does not prevent them from working freely.

The data in Table 1 depict growth performance before and after the institution of an aggressive feeder-management strategy. Contrary to popular belief, reducing the amount of feed present in the pan did not reduce average daily gain. Feed efficiency and daily gain both improved because of decreased wastage and continual access to fresh feed. The author's recommendations are to have feed accessible for newly weaned pigs at all times in feeders that are adjusted correctly to teach the proper feeding behaviour.

Table 1. Comparison of pig performance before and after institution of an aggressive feeder-management strategy in the first week after weaning

Environmental Hygiene

The primary objective of hygiene practices is lowering the dose of infectious pathogens that can be transmitted from the environment. It has been well documented that animal performance is increased in “clean versus dirty” environments and cleanliness is probably responsible for a large percentage of the growth performance benefits from all-in/all-out production.²

Also, because the young pig is more susceptible to infections from enteric organisms, sanitation is especially critical for nursery facilities. Fortunately, most swine pathogens only survive for a brief amount of time outside the host in the absence of organic materials or moisture. Up to 99 per cent of bacteria can be removed by cleaning alone under experimental conditions. However, the relative importance of the stages of sanitation include: 1) 90 per cent removal by removing all visible organic matter, 2) 6 to 7 per cent killed by disinfectants, and 3) 1 to 2 per cent killed by fumigation.³ However, recent reports indicate that environmental contamination is an important contributor of Salmonella infection. One study found that 27 per cent (7/26) of drag samples obtained from a fully slatted finishing floor just prior to placement of pigs were found to be positive for salmonella.⁴

The basic principles of hygiene practices to decrease transmission from group to group from environmental contamination include: 1) Building materials that are easy to clean. Rough surfaces such as concrete are more difficult to clean than smooth surfaces such as wire. Smooth non-porous surfaces will provide easier removal of faecal matter and faster drying. 2) Thorough cleaning and removal of organic matter such as faeces and feed. In general, organisms are protected against agents of disinfection by organic materials such as pus, serum or faeces. 3) Proper use of disinfectants, including dilution to proper dosage and application to the proper coverage area. 4) Proper downtime and drying of rooms. Anecdotal observations from the author's group indicate that there is a seasonal nature to enteric problems in nurseries during the late winter and early spring period. They have observed that during this time, due to environmental conditions, nursery spaces take more time to dry and pigs are commonly placed in nurseries with moist surfaces and humid environments.

A survey of nursery hygiene practices on 129 French farms indicated several practices associated with decreased residual contamination.⁵ These practices included damping of the rooms immediately after the removal of the pigs. The researchers hypothesised that damping prevented dying of the faecal matter and increased the ease and thoroughness of cleaning. Use of a detergent also was suggested as associated with decreasing residual contamination. However, in another study evaluating the impact of detergent, the researchers were unable to detect any impact and residual contamination after thorough washing.⁶ This indicates that using a detergent may be useful to improve the ease of cleaning. However, the detergents may not have much impact on the final amount of residual contamination if cleaning procedures are thorough.

Several other studies indicated that thorough cleaning of organic matter resulted in less residual contamination.^2,6 Additionally, greater distances between the surface of the slurry and the floor were associated with less residual contamination. The authors attributed this risk factor to splash-back and recontamination during the cleaning process.

Finally, factors associated with disinfectant usage were important. These included proper dilution and application of disinfectant. An evaluation of disinfectant ability to reduce infectivity of porcine circovirus type 2 (PCV2) indicates that commonly available disinfectants vary widely in their ability to neutralise the virus (Figure 2;).⁷ This study evaluated 11 commonly used disinfectants in swine farms and research laboratories that included the following disinfectant classes (products tested): ethanol (alcohol), iodine (Weldol), phenol (1-Stroke, Tek-Trol), quaternary ammonium (Roccal D Plus, Fulsan), oxidizing agent (Clorox, VirkonS), alkali (NaOH), and chlorhexidine (Nolvasan). The mean titer after disinfection ranged from 10^5.2 for the chlorhexidine to 10^1.6 for the oxidizing agent VirkonS. This compares to the control titer without disinfection of 10⁶. Thus, a reduction from 10⁶ to 10⁵ results in a 90 per cent reduction, to 10⁴ a 99 per cent reduction, to 10³ a 99.9 per cent reduction and to 10² a 99.99 per cent reduction. There are two important points to remember from this study:

1. PCV2 is a small enveloped virus similar to Parvovirus and, thus, difficult to neutralise with disinfectants.
   
   
2. This study was done under controlled laboratory conditions and optimised for maximal disinfectant activity. Disinfectant activity may be even less effective in the field setting.
   
   

Nonetheless, VirkonS appeared to have the best activity.

Figure 2. Reduction in infectivity of PCV2 after a 10-minute exposure to disinfectant
(Royer et al., 2001)

Until recently, there has been little objective scientific evidence to evaluate hygiene practices in swine operations. With an increased emphasis on evaluating biosecurity practices there have been several recent studies. In addition to the PCV2 disinfectant evaluation, these include the evaluation of farrowing house cleaning protocols, boot bath cleaning procedures and disinfectants, and methods of rapid evaluation of surface contamination in swine facilities. ^2,6,8

Briefly, the evaluation of farrowing house cleaning protocols evaluated the amount of bacterial surface contamination in a sequential manner after low pressure washing of surfaces, high pressure with or without a detergent, and after application of disinfectant. Bacterial counts were generally lowered by two logs (99 per cent) between the low and high pressure washing, whether a surfactant was used or not. Counts were generally lowered by another two logs after disinfection. The major conclusion from this study is that sequential washing and disinfection steps result in reductions in bacteria and each step contributes to the decontamination process.

References

1. Dritz, S.S., Tokach M.D., Goodband R.D. and Nelssen J.L. 1996. Nutritional programs for segregated early-weaned pigs: Part I. Management procedures and nutritional principles. Commpend. Contin. Educ. Pract. Vet. 18:S222.
   
2. Amass S.F., Ragland D. and Spicer P. 2001. Evaluation of the efficacy of a peroxygen compound, Virkon S, as a boot bath disinfectant. J Swine Health and Prod. 9:121-123.
   
3. Morgan-Jones S. 1987. Practical aspects of disinfection and infection control. In: Linton A.H. et al., eds. Disinfection in Veterinary and Farm Animal Practice Oxford: Blackwell Scientific Publications. 144.
   
4. Davies P., J. Funk and W.E.M. Morrow. 1999. Fecal shedding of Salmonella by a chort of finishing pigs in North Carolina. Swine Health and Production. 7(5):231-234.
   
5. Madec, F., Humbert, F., Salvat, G. and Maris, P. 1999. Measurement of the residual contamination of post-weaning facilities for pigs and related risk factors. J Vet Med. 46: 37-45.
   
6. Kihlstrom S., Morrow W.E.M., Davies P. and Luginbuhl G. 2001. Assessing the progressive decontamination of farrowing crate floors by measuring the decrease in aerobic bacteria, J Swine Health and Prod. 9:65-69.
   
7. Royer, R.L., P. Nawagitgul, P.G. Halbur, and P.S. Paul. 2001. Susceptibility of porcine circovirus type 2 to commercial and laboratory disinfectants. J Swine Health and Prod. 9:281-284.
   
8. Kelly J.A., Amass S.F. and Ragland D. 2001. Analysis of Lightning and BioClean tests for assessment of sanitation. Swine Health and Production. 9:207-224.

Further Reading

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