In the Feb 2022 issue of Pig World (, our nutritionist, Steven Laird, published this comprehensive summary on looseness, the causes and risk factors, mitigating and supporting practises, adapting to change and when to intervene.

We have already worked with 27,000 weaners across 30 farms, so if you’re now planning your zinc removal strategy, this article will be a vital read.

Steven Laird
Dr Steven Laird, Nutritionist, Primary Diets

Zinc oxide has been used to control post-weaning diarrhoea (PWD) for decades. However, with the ban on using therapeutic levels of zinc oxide approaching, the industry is under pressure to find alternative strategies to combat looseness at weaning.

Causes of looseness

Firstly, not all looseness is cause for concern.  In most cases, diarrhoea is transient and passes within 3-5 days, often without compromising productivity.  A degree of looseness can be expected at weaning as a consequence of a change in diet form, composition and delivery, and the many stressors of weaning. 

However, PWD is an enormous concern, with this major intestinal disease impacting within the first 2 weeks post-weaning.  It has a complex aetiology but is primarily caused by infection with specific bacterial, viral or parasitic pathogens, most notably enterotoxigenic Escherichia coli (ETEC).  PWD incidence and severity is intensified by unfavourable husbandry conditions and nutrition. 

While many PWD pathogens are likely to be present throughout the farm, weaned piglets are at greatest risk due to their immunological naivety and the stressors at weaning.  Additionally, the feed intake drop commonly observed post-weaning leads to gut deterioration, rendering the animal more susceptible to pathogenic invasion.  

Looseness can also be an indirect consequence of inappropriate nutrition, ie. feeding a poorly digestible diet to piglets results in an accumulation of undigested feed in the gut, which can stimulate the growth of pathogenic microorganisms such as E. coli or Salmonella and in turn result in diarrhoea.

Mitigating looseness

Quality nutrition is vital for piglets to fight off disease, however nutrition alone cannot prevent or cure infection.  Without a single replacement for zinc, a universal approach to management is crucial to successfully control looseness.  An important first step is to minimise exposure to pathogens through effective hygiene practices, biosecurity and vaccination programmes.

Focus should then turn to nutrition: does the diet encourage intake whilst providing nutrients for optimal growth and immune function?  A complex starter diet with highly digestible ingredients, ie.  milk, cooked cereals and fish, is not only more palatable but is also more forgiving on the gut than a simple diet. 

Feed additives can also be used to support gut health and microflora balance (eg. organic acids, prebiotics and probiotics) and while these are not a direct replacement for zinc, they may form part of a nutritional management strategy. 

Creep feeding is encouraged as it stimulates gastro-intestinal tract development prior to weaning.  Where possible, the same pre-weaning diet should be offered for the first few days post-weaning to avoid abrupt changes. 

A later weaning age may alleviate some issues caused by zinc removal, but it will also impact sow productivity and require extra farrowing space. 

Adapting to change

At Primary Diets, we have already worked with customers and their vets to trial zinc removal on over 27,000 weaners across 30 farms, covering indoor, outdoor and straw-based systems, and a range of genetics, weaning weights, feeding regimes and pen sizes.  Our approach is to prioritise animal health first by limiting looseness, often involving feeding a lower specification diet (lower protein and lysine), and then to build back any lost performance.

The results are very encouraging with most units (88%) reporting no or only mild looseness without zinc.  While this gives cautious optimism, health status is variable and issues arise at any time, so all farm personnel must remain vigilant in managing zinc removal.  For the remaining 12% of farms, more extensive changes in nutrition, management and veterinary input will be necessary. 

When to intervene

A slight change in faeces at weaning is expected with zinc withdrawal (looser consistency and/or darker colouration), and change is not necessarily reason for concern. 

Knowing when to intervene (ie. looseness that compromises animal health) is paramount and this will be dependent on good stockmanship and veterinary support.

One clear observation from our research is that no two farms are the same for zinc removal.  Without a ‘one-size-fits-all solution’, collaboration between producers, their vets and nutritionists is critical for success.

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