Stakeholders in the pork industry worldwide are currently facing a growing demand for protein, which they must produce with fewer resources while ensuring productivity gains for producers. Meanwhile, one of the biggest challenges for breeders, veterinarians and nutritionists is that of rapidly finding effective solutions to reduce use of antibiotics in livestock farming, bearing in mind that use of Zinc Oxide (ZnO) for therapeutic purposes will be banned in Europe by 2022. These new constraints will require changes in farm management practices, and in particular the management of hyperprolific sows and their piglets which are more fragile at birth. Early establishment of a diverse microbiota and development of immunity are essential to avoid an upsurge in digestive disorders, particularly after weaning. Various strategies are possible, including use of live yeast and/or selected yeast fractions in sow and piglet feed. In fact, several studies have shown the benefits of yeast in terms of both establishing a diverse microbiota (Kiros et al., 2019) and promoting the development of immunity (Jurgens et al., 1997). Finally, yeast and yeast fractions can “capture” pathogens (Posadas et al., 2017) and thus limit their adhesion to intestinal cell walls, hence reducing inflammation and the associated diarrhoea.

Two trials were carried out to verify and evaluate these effects on the performance of weaned piglets, one at an experimental centre (Vivafarm, Agrofeed, Hungary), the other at a commercial farm in Italy.

1. Materials and methods

1.1. Animals, feeds, and parameters measured

Study 1 was performed at a farm with 200 sows ((NF x L) F1 x DanAvl Duroc). Fourteen sows were selected and divided into 2 groups, one control group (C) and one yeast group (Y), according to their weight and parity. At weaning, 88 piglets from their litters were selected and separated into 2 groups (n=88*2), one control group (C-C) and one yeast group (Y-Y). The sows in both groups received the same lactating sow feed one week before farrowing and throughout lactation. The sows in group (Y) received supplementation in the form of 1 kg/t of Actisaf® live yeast and 0.250 kg of Safmannan® yeast cell wall (Phileo by Lesaffre, France). At weaning, the piglets in group (C-C) were fed a pre-starter feed containing 1600 mg/kg of ZnO + 180 mg/kg of colistin for 18 days, and for the following 29 days a starter feed containing 1000 mg/kg of oxytetracycline. The piglets in group (Y-Y) received pre-starter and starter feeds containing neither antibiotic nor ZnO, but with the live yeast / yeast cell wall
supplementation. The individual weight of the piglets at weaning, the average daily gain (ADG), the feed conversion ratio (FCR) and the weight of the piglets during the pre-starter and starter phases were all measured.
Study 2 was conducted in a post-weaning environment, where 492 piglets aged 28 days and weighing 7.2 kg were separated into 2 homogeneous groups, one control group (C) and one yeast group (Y), according to their weight and sex.

The piglets in group (C) were fed a pre-starter feed for 18 days containing 3000 mg/kg of ZnO and a starter feed without ZnO. The piglets in group (Y) received the same pre-starter and starter feeds without ZnO and containing the live yeast (0.8 kg/t) / yeast cell wall (0.3 kg/t) combination. Bodyweight, Feed Intake, the diarrhoea score, mortality, and treatments during both phases were all measured.

1.2. Statistical analyses

Statistical analyses of all measured parameters were performed using an ANOVA test. Data were considered significant when p < 0.05.

2. Results

2.1. Trial conducted at an experimental farm

Although the individual birth weight was lower for the piglets in group (Y-Y) compared with those in group (C-C) (1.42 vs. 1.67 kg respectively; NS), weaning weight was slightly higher after 26 days of lactation (7.64 vs. 7.46 kg respectively; NS). Feed intake of the sows in group (Y) tended to be higher (Y: 174.36 vs. C: 165.21; p = 0.08), with a lower body weight loss at the end of lactation (Y: 14.8 vs. 15.2; NS).

Throughout the post-weaning period, the performance of the piglets in group (Y-Y) was the same as those of the piglets in group (C-C) in terms of ADG (480 vs. 480 g/d respectively), FCR (1.47 for both groups) and live weight at the different stages (Figure 1).

2.2. Trial at a commercial farm

Although there was no significant difference, the feed intake of the piglets in group (Y) was more consistent than that of the piglets in group (C), with the latter showing a slight decrease in consumption after removing the ZnO. The average weight between the 2 groups after 28 days of testing was not significantly different (Y: 12.5 vs. C: 12.1 kg respectively; NS).

Post-weaning mortality was slightly lower in group (Y) compared with group (C) (4.1 vs. 5.2% respectively; NS) and the number of antibiotic treatments was reduced in group (Y) compared to group (C) (Figure 2).

There was no difference in the diarrhoea score between the two groups.

Conclusion

To meet the challenges posed by hyperprolific sows and to prepare for the ban on the use of ZnO for therapeutic purposes, particularly in Europe, it is important that various alternatives are investigated, including pre- and probiotic based solutions, before their implementation at farms. In these studies, the combination of yeast solutions helped maintain animal performance at the same level as treatment with ZnO, while controlling diarrhoea phenomena and the associated antibiotic treatments as well as the mortality which can occur in the first weeks post-weaning.

Therefore, these two trials confirm the benefits of sow and piglet feed supplementation with a combination of yeast sources as an alternative to ZnO use for therapeutic purposes to prevent diarrhoea.