18 Jul 2016
Thomas Iveson, Svetlana Sungailaite and Eduardo Velazquez discuss the challenges of efficient pig production and how disease control and good management strategies are important to a successful outcome.
Newborn piglets are vulnerable, wet and their production of body heat is limited; thus, good farrowing accommodation management is key.
The UK pig industry has a wide variety of production systems that broadly fall into two categories: indoor units, which make up 60% of production, and outdoor units, which make up 40%.
The distinction, however, can be very difficult to make, with many production systems combining the two. This variety of systems leads to a wide range of challenges – for example, how to easily handle sows, housing of young piglets in a controlled way, or waste management versus land use.
When it comes to pig production, everything starts in the farrowing house, where attention to detail is central to achieving maximum productivity on the farm. The farmer aims to wean the maximum number of well-grown healthy piglets. To achieve this, low levels of preweaning disease and mortality are key.
Newborn piglets are vulnerable, wet and their production of body heat is limited; therefore, good farrowing accommodation management is vital. This can be much easier to achieve on indoor versus outdoor systems. Monitoring allows staff to provide help in cases of sows having difficulties farrowing or to help the smaller piglets survive (Dewey et al, 2008; Baxter et al, 2013). This is especially vital because most preweaning mortality occurs within 72 hours of farrowing (Johnson et al, 2007; Tuchscherer et al, 2000).
As with other species, good colostrum intakes during the first hours of life are crucial to ensure piglet viability. The amount necessary to reach the peak of IgG absorption is 200g of colostrum within the first 24 hours. This timescale is key because the absorption of the immunoglobulins in the small intestine drops to a low level after 24 to 36 hours (Devillers et al, 2011; Kruse, 1983).
To maximise this intake, different techniques can be used – for example, split suckling, which consists of splitting the litter into two groups, based on size. We then restrict the larger piglets’ access to the udder for short periods to ensure the small ones suckle. This goes alongside directly assisting weaker piglets to suckle and, if needed, hand feeding the colostrum.
In the UK, it is often necessary to carry out tail docking and teeth grinding in piglets younger than three days old. The aim is to reduce the incidence of tail biting (with tail docking) or piglet facial necrosis and sow udder damage (with tooth reduction). These procedures may only be carried out where measures to improve environmental conditions or management systems have first been taken, but have only been partially successful (The Mutilations [Permitted Procedures] [England] Regulations, 2007).
Also, to prevent anaemia in piglets, the use of iron injections from three to five days of age is generally seen as essential in indoor-reared piglets (Loh Jr et al, 2001). Piglets are also frequently given an oral coccidiostat in the first week of life to help reduce the effect of coccidiosis, which is often endemic within housed systems.
Suckling piglets are vulnerable to infection and the most common diseases during the preweaning period include:
Some of these diseases can be controlled through vaccination protocols for the sows and gilts. This will give the piglets passive immunity against the diseases through the colostrum (Kristensen et al, 2004). Erysipelas, PRRS, enteric diseases (E coli, Rotavirus and clostridia) and streptococcal meningitis are the most common diseases vaccinated against in this manner.
Some vaccines are given directly to piglets preweaning. The most commonly used in the UK are targeted at enzootic pneumonia, porcine circovirus and PRRS. The timing of these vaccines varies depending on the product and the timing of the disease challenge (Haake et al, 2014). Vaccines given to piglets preweaning are to protect them in the growing and finishing stages of production.
Creep feeding of a solid diet to piglets while they are still suckling the sow is essential in preparing their digestive system for weaning. It initiates and promotes gut and digestive enzyme development, enabling piglets to digest nutrients from sources other than milk. Milk production peaks at around 12 to 16 days for most sows, before declining through to weaning (British Pig Executive, 2013).
During suckling, the villi of the small intestines of piglets are constantly bathed by the sow’s milk, which contains IgA. This becomes absorbed into the mucus, covering the villi surfaces and preventing E coli and other organisms attaching to the fingers (Muirhead et al, 2013). After weaning, IgA is no longer available and pathogens begin to damage the villi, causing them to shrink. Creep feeding minimises villus atrophy and crypt hyperplasia, and studies have also shown conditions such as post-weaning diarrhoea are reduced in creep-fed piglets (Makinde et al, 1997).
Weaning is a period of intense stress for piglets, with profound consequences for growth, physiology and disease outbreaks, leading to welfare problems. Data has shown nutritional deficits during the transition from milk to solid food can cause severe adaptation problems for many piglets (Pluske et al, 2003).
Weaning age is usually 28 days and the period of rapid change in relation to feed intake, metabolism changes and tissue thermal insulation must be well-managed. During the first 10 to 14 days after weaning, environmental conditions are very important for a successful weaning and a stable ambient temperature of 26°C to 28°C is recommended for piglets penned on slatted floors (Pluske et al, 2003). This can be reduced by 2°C to 3°C per week once regular feed intake is established. The construction and maintenance of housing is essential and the minimising of draughts is a priority because they have a negative effect on piglet development. Attention should also be paid to stocking densities, group size and hygiene.
As previously mentioned, disease post-weaning is common, with the respiratory tract and digestive systems being most frequently affected. However, another key disease is meningitis, which is often caused by Streptococcus suis.
Multiple pathogens are often involved in post-weaning disease, with one of the most damaging being PRRS virus (PRRSv). This virus, if uncontrolled, can cause severe immunosuppression and can severely worsen many disease problems such as S suis meningitis.
PRRSv and swine influenza are the key viral pathogens involved in the post-weaning respiratory disease complex with secondary bacterial components primarily including Pasteurella species, Mycoplasma hyopneumoniae, H parasuis and streptococci (National Animal Disease Information Service, 2016).
As well as respiratory disease, post-weaning diarrhoea caused by E coli and Salmonella is common.
E coli is also responsible for oedema disease, which occurs when pigs are infected with a particular strain of haemolytic E coli producing Shiga toxin (Merck Manuals, 2015). This attacks the blood vessels causing localised oedema in the gut, brain and peripheral tissues. Common clinical signs include sudden death, puffiness above the eyes and neurological signs. Although the site of infection is the gut, diarrhoea is not a feature (The Pig Site, 2014).
Because the weeks post-weaning are a key period of disease challenge, it is this age group of pigs where in-feed antibiotics are used most commonly. This is especially the case when tackling diarrhoea and meningitis. Non-antibiotic strategies to tackle these problems are, however, becoming more common. An example would be adding organic acids to the water supply to help tackle E coli (Tsiloyiannis et al, 2001).
Porcine circovirus used to be a major cause of poor performance post-weaning, but since vaccines have been introduced, clinical signs of this disease have virtually disappeared from farms.
Once the piglets are over the initial stage post-weaning, they tend to be more resilient to disease; however, respiratory disease and diarrhoea remain as prevalent issues. Diseases during the later stages of production tend to rumble on in the background and, rather than causing death, they often suppress growth rate. Two of the most common include M hyopneumoniae causing enzootic pneumonia and Lawsonia intracellularis causing ileitis.
Nutrition is key post-weaning to ensure good growth rates and feed represent 70% of rearing costs. As a rule, most pigs will be fed three types of diet post-weaning: starter, grower and finisher. The starter ration is the most expensive, but is imperative to ensuring good performance post-weaning (The Pig Site, 2010). Feeding post-weaning is generally on an ad-lib basis to promote maximum possible growth rates. It is vital pigs are able to convert feed efficiently for any margin to be achieved. Any disease or management challenge will reduce this efficiency and thus damage profitability.
Environmental enrichment is a requirement under farm assurance schemes to minimise negative behaviours, such as tail biting. The use of items including balls, hard plastic chews, chains and plastic pipe, along with paper, cardboard and bedding materials, can provide sufficient distraction for most pigs – the principle being to keep pigs occupied for longer than being solely reliant on food, while encouraging natural behaviours, such as rooting.
Overall, efficient pig production can be challenging, especially as margins are very tight and any uncontrolled diseases or poor management strategies can be the difference between success and failure.
