Lowering antibiotic usage is easier said than done, as it usually coincides with a drop in farm margins.
Dr John Patience, a professor in animal science specialising in pig nutrition at Iowa State University in the US, says this is primarily due to higher mortalities, but also because, as production becomes more labour-intensive, pigs take longer to reach slaughter weights and require more vaccines and floor space to thrive than conventionally produced pigs.
The general trend, therefore, is not an outright ban on antibiotics, but a shift away from using them as growth promoters. In addition, disease treatments are becoming more focused.
Where blanket treatments might have been given preventively in the past, the idea now is to treat only sick individual animals when the risk of infection is high,” he says.
“Group treatments are seen as a last resort when all other alternatives have been exhausted.”
Greater emphasis is also being placed on correct diagnostics to ensure the right antibiotics are used at the right dosage to treat specific diseases.
The dosing procedure is also kept as short as possible, which is why antibiotics are increasingly delivered in water rather than feed. This is easier and simpler, and sick pigs tend to drink water rather than eat, especially after weaning.
Biosecurity and hygiene
A multidisciplinary approach involving improved genetics, animal husbandry and nutrition, as well as better health management, building engineering design and operation, is required to offset the negative spin-offs of lower antibiotic usage. Patience, however, places hygiene and biosecurity at the top of this list.
“Biosecurity should be redoubled, as it’s your first line of defence against disease. Its ultimate goal is to prevent anything that might be carrying a harmful organism from getting near your animals.”
This means keeping strangers and vehicles off the farm, providing shower facilities attached to the pig houses, and donning clothing and boots only for use in the pig houses.
also means an aggressive pest management programme to keep rats, mice, birds and other animals out of the production area.
Equally important is controlling traffic of pigs onto the farm and into the pig houses, and incorporating new animals into a group only once their health history, source and status have been cleared.
Along with this comes cleanliness. Patience explains that many infections are dependent on the degree to which animals are exposed to the disease, and cleanliness minimises exposure.
Growing awareness of the importance of biosecurity and cleanliness has led to batch farrowing and all-in, all-out systems becoming increasingly popular.
Splitting the animals up into groups according to nutritional and management requirements eases production management. It also enables all the animals to be vaccinated on the same day.
To reduce the build-up of pathogens, rooms or buildings should be thoroughly sanitised once all the pigs have been moved out and before another group is moved in.
The water storage and delivery systems are sometimes neglected, and Patience stresses that they should be treated frequently to prevent pathogens from entering the production site, and to avoid the formation of biofilms in pipes and storage cisterns.
Stockmanship
Stockmanship is generally defined as the ability to read an animal’s needs by paying attention to its behaviour, appearance and sounds, as well as the production environment and quality of food and water.
“Good stockmanship is non-negotiable,” says Patience.
“It ensures that pigs are well cared for, welfare is top notch, and production is efficient and profitable. No amount of diet formulation, feed additives, medications or expensive housing will overcome poor stockmanship.”
For example, at feeding time, pigs don’t need an invitation to join the feast, but move en masse to get to the feed.
Something is usually wrong when a pig does not participate and lies listlessly in a corner. Agitation, aggression, scratching, coughing, sneezing and laboured breathing are also signs of a problem.
It is not always possible to move all sick pigs to the sick pen, so if a single treatment results in recovery, the pig is normally left in the pen.
If illness persists, it should be moved to an isolated pen for treatment and care If the animal fails to respond to this, it should be euthanised to stop it suffering and prevent other pigs from becoming infected.
Health management
While health management is important throughout production, special attention should be given to newborn and newly weaned piglets. Animals neglected during these phases usually never catch up with well-cared-for animals.
This means ensuring they do not suffer from cold stress, each piglet receives enough good-quality colostrum within the first hours of life, and intervening when sows fail to produce enough milk.
To ensure piglets can stomach solids, the weaning age can be moved up to a week later. Where weaning at three weeks used to be seen as the best for overall sow productivity, many producers are switching to 23 to 25 days, with no loss in sow productivity and an improvement in weaned pig transition.
“The older weaning age is often driven by the desire to reduce antibiotics usage,” he explains.
Feed regime
According to Patience, diet formulation and composition are critical components of reduced antibiotics systems. This is because, firstly, feed can predispose pigs to digestive upset, and, secondly, it can serve as a vehicle for the delivery of protective products.
“Feed ingredients, in effect, are no longer evaluated only on their nutritional value and palatability, but on their functional properties in terms of their impact on the structure and functioning of intestinal tissue, the microbiome, oxidative stress and immune function.”
Preliminary studies suggest that dried distillers’ grains with solubles, a by-product of ethanol production from wheat, barley, sorghum or maize, should be avoided or used at low levels for pigs susceptible to swine dysentery. By contrast, milk products such as whey or casein have been found to be highly beneficial in newly weaned piglets’ diets.
“The trick with diet formulation is to minimise nutritional stress, especially when it comes to intestinal problems,” says Patience.
“For weaners, for example, it’s best to feed a diet low in protein and high in digestible ingredients, to minimise the proportion of feed that passes undigested through the lower gut. Undigested nutrients and excess protein that reach the large intestine may encourage the growth of pathogenic bacteria, leading to diarrhoea.”
The fermentation of feed prior to delivery has been shown to have numerous advantages for the young pig, including lower pH and reducing the pathogen load in the feed itself.
Many feed additives have been developed to enhance pigs’ health and performance, especially post-weaning.
These include prebiotics, direct-fed microbials (previously referred to as probiotics), enzymes, essential oils, egg yolk antibodies, and speciality proteins, such as spray-dried plasma of porcine or bovine origin. The use of xylanase enzyme improves the digestibility of feed and reduces mortalities.
Besides this, fibre sources need to be selected more carefully. Patience says insoluble, poorly fermented fibre increases the rate of passage and has an abrasive effect on the intestine lining, leading to diarrhoea.
Ingesting more soluble and fermentable fibre may also result in less severe diarrhoea, however, by imparting a prebiotic effect on the intestine. For young pigs, soluble and fermentable fibre would be helpful where E. coli might be a problem, whereas insoluble fibre might be the better option in pregnant sows as it will help to provide a sense of satiety.
The choice of ingredients will depend on the affordability and availability of ingredients, he says, so it makes sense for a farmer to ask a pig nutritionist to help develop a customised programme.
（January 20, 2021. From “Farmer’s Weekly” )
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Post time: Jan-20-2021