Alternatives to pharmacological zinc oxide
Recruiting the sow to help offspring at weaning using yeast
By Brenda Christensen, Hagen Schulze, Lee-Anne Huber and Elijah G. Kiarie
Weaning is one of the most stressful periods for pigs throughout the pork production cycle. Currently, piglets are exposed to many stressors, including diet changes and immunological challenges, that result in reduced feed intake and a post-weaning growth lag.
Historically, in-feed antibiotics and pharmacological doses of Zinc Oxide (ZnO) have been used to promote growth during the post-weaning period. However, these are prohibited or in the process of being banned in many jurisdictions including those in the European Union and other pork producing countries. Therefore, the development of sustainable and cost-effective strategies that can support pig growth and digestive physiology following weaning are necessary.
A major issue during weaning of the piglets is their low feed intake. This means that feed additives provided in the diet are usually not consumed in high enough quantities to have consistent, positive effects. Thus, we took a different approach. In this study the sow was provided with a yeast product meant to stimulate the immune system and increase the transfer of immunoglobulins to the offspring.
There are many yeast products on the market, from living microorganisms (probiotic yeast), to inactivated, intact or enzymatically treated yeast (all potentially categorized as postbiotic). Postbiotics offer physiological benefits to the host through functional components of the inactivated cells and cell growth media (i.e., metabolites).
The yeast product used in this current study is an enzymatically treated Saccharomyces Cerevisiae) which is considered a postbiotic (PY; LivaltaTMCell HY40, AB Agri Ltd., Peterborough, UK). This additive is a co-product of bioethanol production and contains high levels of protein (min 36%) and cell wall components, β-glucans and mannan oligosaccharides (40%). These cell wall components have immune modulating properties that make this additive particularly favorable for pig diets.
By targeting the sow as opposed to the offspring, a more consistent improvement is expected due to high feed intake of the sow as opposed to newly weaned nursery pigs. The objective was to determine the optimal inclusion level of PY fed to sows during late gestation and lactation to maximize immunoglobulin transfer and offspring growth performance.
The PY was fed to parity one sows in gestating (day 85-110 of gestation) and lactating (day 111 of gestation until weaning at approximately 21 days after farrowing) diets at 0, 0.25, 0.50, 1.0, or 1.2% to determine an optimal inclusion level. Piglets and sows were weighed within 24 hours of birth (considered day 1) and again at weaning.
Blood (piglets and sows) and colostrum were collected 24 hours after birth of the first piglet and blood, and blood was collected again at weaning. Blood plasma and colostrum samples were analyzed for immunoglobulin (A, G and M) concentrations. The time between the birth of the first piglet and colostrum collection was recorded (minutes) and used in the statistical model when comparing immunoglobulin concentrations on day 1.
In this study, while we observed no differences in birth weight between treatments, at weaning offspring from sows fed 0.25% PY were 820g and 660g heavier compared to offspring from 0%PY and 1.2%PY fed sows; respectively (Fig. 1).
Directly following birth, piglets can absorb maternally derived immunoglobulins. The more immunoglobulins’ piglets can consume and absorb, the better they will be protected against pathogens.
However, maternally derived immunity declines as piglets get older, and dips around weaning, prior to the maturation of the piglet’s own adaptive immune system. Therefore, it is hypothesized that greater plasma immunoglobulin concentrations at weaning will assist in the pig’s ability to fight infectious agents.
Overall, on day 1, there were limited differences in immunoglobulin concentrations in colostrum, sow, and piglet blood plasma (data not shown). However, at weaning, blood plasma immunoglobulin A (IgA) concentrations in sows fed PY and their piglets had higher IgA concentrations than the control (PY0%; Fig. 2).
Although, there were no differences in colostrum IgA concentrations, it is possible that piglets from the PY0.25% group consumed more immunoglobulins due to increased milk consumption as indicated by the heavier weaning weights. Therefore, an inclusion level of PY0.25% fed to gestating and lactating sows was optimal, as it resulted in increased weaning weight, and plasma IgA concentrations in offspring at weaning.
Additional work is currently being conducted to determine the lifetime performance of offspring from sows fed PY0.25%. As the European Union and other pork producing countries move away from current dietary strategies to improve post-weaning growth (i.e., pharmaceutical ZnO), global efforts are being made to develop effective, and environmentally sustainable alternatives.
This study shows that yeast products-, such as PY fed to sows, can contribute to improving offspring growth and immunocompetence at weaning.
Christensen is a doctoral student, Huber is an assistant professor and Kiarie is a professor of monogastric nutrition, all in the Department of Animal Biosciences, University of Guelph. Schulze is an innovation and technical Lead at Livalta, an AB Agri company.
