Feed additives

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"Whatever animals eat is important for their growth"

Professor John Pluske, associated with the Murdoch University in Perth, Western Australia, is one of the world’s leading authorities in the field of the nutrition of young animals. Applying correct feeding cannot start early enough – get to it way before farrowing.

Raised in a city, with school holidays out in the country on farms sounds like an ideal carefree childhood for many and while it was undoubtedly thoroughly enjoyed by the young Prof Dr John Pluske it also helped lay the foundations for a distinguished career as a pig nutritional digestive physiologist in his native Australia, as well as in other pig-producing nations around the world where his knowledge and advice is much sought after today.

John Pluske

Prof John Pluske is a nutritional digestive physiologist with expertise in the nutrition and growth and development of the young pig. A graduate of The University of Western Australia, where he gained both a Bachelor of Science (Agriculture) and Doctor of Philosophy, he is currently a professor at the School of Veterinary and Life Sciences at Murdoch University in Perth, Western Australia.

Small piggery

By good fortune, one of the last farms he worked on as an undergraduate student during the summer university break had a small piggery on it, which grabbed his interest, especially the piglets.

"I got really involved with these piglets and when I had to find a small mini-research project to do in my final undergraduate year, I decided to look at split weaning for piglets. Then, after a year of broad acre farming, I went back to the University of Western Australia and did a PhD (with Dr Ian Williams as supervisor) in the physiology, morphology and enzymeology of the small intestine in response to nutritional and social stress imposed on piglets at weaning. His interests have remained in this area, with subsequent post-doctoral studies in Canada (1993-1994). Dr Pluske has also worked with cats and chickens (Massey University, New Zealand) and with dogs at Murdoch University, with the studies in these species also related to nutrition and digestive physiology.

Nutrition is important

His work has helped in developing the concept that nutrition is important right from the very start of life for piglets, well before they are even born. "Whatever animals eat is important for their growth and development and it's best for them to get the right nutrition as soon as possible," he says.

"Once you get down to the cellular levels there is good evidence to show biology at work and the way different nutrients impact upon the physiological function of the animal, whether that be in the liver, the heart, the brain, or the gastro-intestinal tract. What we eat is pretty much reflected in the phenotype. There is obviously a genetic component to physiological function, but there is also a strong nutritional component.

"It's an area that is being increasingly focused upon in pigs, with gene sequencing techniques and with the way we are mapping the microbes in the animal, as well as our understanding of that physiology-nutrition link and metabolism, of course. You can really start to drill down now into the effect of specific nutrients on functions."

Alternative ingredients

As far as the search for 'alternative ingredients' goes to reduce the reliance on antimicrobials in the post-weaning period, Pluske does not see anything new immediately on the horizon. "I wish there was, so that we could definitely say that ingredient 'x' reduced diarrhoea for example, however in saying that we really need to look at the whole package because there are some ingredients, existing and in the future, that will play a role in this area. And of course there are also feed additives that play an important role. I think it's more about a suite of interventions encompassing diet, disease control, management and the environment, to assist that post-weaning transition."

He points out that increasingly it is becoming recognised that the formation of the foetuses can be influenced in utero by what is fed to the sow, as well as the behaviour and environment of the sow, and producers need to be aware of this. Whatever the animals eat is important from the growth and development point of view, with different nutrients having a far-reaching effect on all the organs, as well as the young pig's metabolism and health – and especially during the weaning and post-weaning periods.

Effect of the environment

"We are just starting to appreciate how much effect the environment has on piglets, with noticeable differences, for example, between those raised outdoors, compared with ones that are reared indoors, where producers have more control over the environment, even if they are fed the same diets and are of the same genotype," he adds, though he hedged around the question of whether he thought it was better for piglets to be indoors, or outdoors. "That depends on so many different circumstances that it would be in appropriate to say one is better than the other, without considering the particular issues facing specific producers."

When talking to producers about the right weaning age, Pluske says that in his view a later weaning age is better for the young pig, pointing out that he and others have done work weaning out to at least five weeks of age and while they still suffered a setback, the magnitude of that setback seemed to be less than if they were weaned younger, and especially if pigs were lighter at an earlier weaning age. However, he admits it largely depends on the economics of the particular pig operation in question, suggesting that a detailed whole-of-operation financial analysis needed to be done before deciding on weaning ages.

Asked what he would use to feed his own imaginary herd of piglets on, Pluske laughed and said: "I think I would choose something based on milk, because it's an ideal substrate for a young animal – but obviously you cannot always provide that and the question really boils down to margin over feed cost. However, it also depends on any local or national restrictions."

Antibiotics

Regarding the use of antibiotics, a subject that has led a lot of debate in international circles, he believes that "in general, producers would rather not use them, even in countries where they are still legal, because of cost, antimicrobial resistance and ever-increasing concerns and restrictions related to their use. But in some situations they feel they need to use them to medicate, or feed medicate just because they have to and then it becomes a welfare issue for the animals.

"Again, it depends on the circumstances that particular producers are facing. I don't think there is any doubt that if you are getting good performance and healthy pigs in the absence of them then why would you include them – and certainly producers here (in Australia) as in Europe and many other parts of the world have developed diets in conjunction with appropriate management strategies, disease mitigation strategies and environmental strategies to be able to exclude some antibiotics, certainly on the growth promotion side; so you can do it, it is possible. There is some pain involved initially of course but it can be done.

Confessing he was 'a bit ambivalent' about the idea of banning antibiotics completely, Pluske says: "I think there needs to be a recognition that they will always have a place or role in production to treat disease and prevent animals suffering. If animals are sick, you have to treat them."

Improving pig production and pig health

Currently back in Perth, where he is a professor at the School of Veterinary and Life Sciences at Murdoch University, Pluske says he now spends most of his time doing research aimed at improving pig production and pig health, especially in the post-weaning period.

While still optimistic about the future for the global pig industry, Pluske is more circumspect about the move towards highly fecund sows giving birth to ever increasing litter sizes with co-related mortality, health and production issues. "The breeding companies still seem to be on an upward trajectory in this respect and I think we need to look more closely at how producers can manage and feed these sows and their piglets properly on both the nutrition and welfare fronts. This is an area that certainly needs more attention."

He also believes there is also "still plenty of room for new research into developing ways to feed and manage sows in gestation and into lactation with respect to nutrition and how you can influence the phenotype of the piglet with sow nutrition and feeding – there is some remarkable research coming out that nobody would of thought about before. We are right at the very start of this work," affirms Pluske.
This interview has been made possible with the kind assistance of Trouw Nutrition.

Roger Abbott

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