|Fresh from presenting these results to the Center for Research in Pig Production and Health’s 2018 Pig Seminar, the lead researcher Professor with special responsibilities in Sustainable Animal Nutrition Mette Olaf Nielsen, Head of Animal Science Studies at the University of Copenhagen’s Department of Veterinary and Animal Sciences, spoke to Feedinfo News Service about the implications of these findings.
As Prof. Nielsen explains, the study compared 9 groups of 50 piglets each from 10 days pre-weaning through their exit from the weaner unit, and they will be followed until slaughter. The groups included a negative control group fed with neither zinc oxide nor fermented rapeseed, a zinc oxide positive control group (2500 ppm), and seven groups (in total 350 piglets) whose diets contained various proportions of fermented rapeseed (from 8% up to 25% of dietary dry matter). Researchers were looking for determinations of weight gain in individual piglets, feed consumption (at pen level), treatment group, the incidence and duration of diarrhea symptoms, and recording mortality.
The results, Prof. Nielsen said, took her by surprise. “We had expected the piglets fed with prefermented rapeseed would do better than the ones that didn’t receive anything, but not as well as the ones that received the 2500 ppm zinc, but the fact is that those that received the prefermented rapeseed from 10% inclusion rates and upwards, they actually had higher average daily weight gains than even those receiving zinc, and at pen level the feed conversion rates were as good as in the zinc supplemented group,” she explained.
Post mortem examinations conducted on piglets harvested 15 days after weaning confirmed at the gut level what had been borne out by the piglets’ productivity; when small and large intestines were collected for histological examination from the groups fed prefermented rapeseed, “on the 10% inclusion level we found that the villi in the small intestine had increased almost 35% in height, and at the 8% inclusion level, the height of enterocytes had increased by 22%. Furthermore, in none of the piglets that had received the rapeseed product, irrespective of the inclusion level, did we see signs of invasion of immune cells in the small and large intestinal epithelia, and they lacked pathological changes which would indicate damages to the epithelial barrier function, and they had a more well-developed brush border. This was not the case for either the negative control group or the zinc supplemented group.” Overall, she said, the fermented rapeseed diet brought 90% of piglets though the weaning period without either use of antibiotics or zinc oxide.
When it came to diarrhea, Prof. Nielsen explained that the piglets fed prefermented rapeseed did not have lower incidences of diarrhea symptoms compared to the negative control group; however, although symptoms resembling diarrhea were observed, this were not associated with the higher mortality observed in the negative control group, nor, as mentioned, did post-slaughter examinations reveal the signs of intestinal damage observed in the negative control group. “Actually, the signs of intestinal damage were more pronounced in the pigs fed zinc oxide,” she observed, while in the negative control group, “piglets had deteriorated body conditions, there were signs of intestinal damage, and villi damage and enterocyte damage…[which] are indications of a pathogenic induced infection.” She therefore hypothesizes that the diarrhea symptoms observed in the prefermented rapeseed-fed piglets were rather signs of a feed induced osmotic effect, explained by high levels of lactic acid in the gut which can draw water into the stool, rather than signs of a pathogenic infection.
What could account for these effects? Of course, lactobacillus’s positive impact on gut health has been understood for a while, but Prof. Nielsen acknowledges its use as a probiotic in feed “has been tested, and the results have been variable in different settings under practical farm conditions.” Her hypothesis: “it may not just be the lactobacillus in itself, but a combination of lactobacillus prefermenting a special feed and potentially producing interesting metabolites which favors gut health.” She goes on to say that the markedly elevated levels of lactic acid observed in the feces of piglets fed the prefermented rapeseed product strongly indicate that the lactobacillus in this compound survive the stomach environment and reach the intestines alive to exert a probiotic effect throughout the gut.
Still, Prof. Nielsen advises, the research is not yet complete and the group is still awaiting results for characterisations of the piglets’ microbiota, which could improve their understanding of the underlying mechanism for the positive effect of the prefermented rapeseed on gut health. “That of course is something we are going to look into, this is just speculation, but what happened to the piglets [i.e. the impacts on growth], that’s for sure, but whatever the reason is…that remains pure speculation.” Indeed, despite Prof. Nielsen’s confidence about what her own team observed with their individual weighing of piglets, she is careful to acknowledge the limits of the present findings, drawn from a pilot study with only one pen per group of 50 piglets. “If we can confirm the results, however, it would be possible to raise pigs without feeding them zinc oxide and without an associated increase in use of antimicrobials for diarrhea treatments. But of course we need to confirm whether what we see here is repeatable.”
Nevertheless, the results are extremely intriguing, not least because of the setting in which it took place. “This is a farm that is running a conventional scheme. …[Antibiotic free production] is generally very difficult to do if you do not also alter a lot of management [techniques] in your herd. In this herd, it was all standard procedures… and they managed to get as good production results without any kind of medication as they had done previously with the inclusion of zinc.” explains Prof. Nielsen. “I personally had not expected these piglets would actually do so well. The manager of the farm certainly hadn’t expected that either.”
Naturally, this is all quite exciting for the company behind the fermented rapeseed product, Fermentationexperts AS (as well as for its manufacturing subsidiary European Protein AS). Jens Legarth, CEO of Fermentationexperts AS, suggests this could bring about a paradigm shift in the feeding of young piglets, saying that until now, rapeseed has not been appreciated for these applications: “Everyone says that you should use a highly digestible protein, such as fishmeal. Nobody is promoting a 25% rapeseed diet for piglets,” he says. However, if prefermentation can render rapeseed meal not only digestible for young pigs, but also deliver the kind of gut health benefits this pilot project suggests, it could be a game-changer for this ingredient.