Skipping antibiotics during the weaning phase is a multifaceted challenge. Research indicates that instead of relying on one solution, successful antibiotic-free strategies require a comprehensive approach, e.g a weaning game plan. This can be achieved utilizing an in-feed application of algae β-(1,3)-glucan, Bacillus sp. PB6, and encapsulated organic acids.
The weaning period is a highly stressful phase in pig production due to the psychological and managerial changes that can lead to post-weaning diarrhoea (PWD) and reduced daily gain. PWD, commonly occurring at weaning and frequently linked to enterotoxigenic E. coli infections (e.g., K88 or F4), causes significant economic losses for the pig industry each year and necessitates higher antibiotic use.
The treatment for PWD frequently depends on antibiotics. Although antibiotic usage varies significantly across different regions, a scientific review conducted in Belgium observed that the vast majority (93% of total antibiotics) administered were for prophylactic purposes, while metaphylactic or therapeutic use constituted a much smaller portion (7% of total antibiotics) (Lekagul et al., 2017). This review also highlighted that antibiotics were predominantly used during suckling and post-weaning periods, with gastrointestinal infections being the most common reason for their administration. Application of pharmacological doses of zinc oxide (ZnO) in post-weaning piglet diets - usually to a level of 2500 ppm of zinc - used to be commonplace across the industry to control PWD. However, from 2022, the use of high doses of ZnO has become prohibited in the European Union. With limitations on the use of antibiotics and ZnO, it is crucial to adopt alternative strategies. This is a complex task that necessitates a multi-faceted approach.
A trial was carried out in weaned piglets from 28 days of age to 70 days of age in semi-commercial conditions in the UK, to evaluate the efficacy of a combination of three in-feed solutions (algae β-(1,3)-glucan, Bacillus sp. PB6, and encapsulated organic acids) compared to a positive control (ZnO).
A linear β-(1,3)-glucan derived from algae (Euglena Gracilis) was selected for supporting the immune system and increasing resistance to disease. Bacillus Velezensis PB6 (ATCC PTA-6737) that originate from animals that resisted an enteritis outbreak, was used to effectively promote a healthy microbiome and reduce the risks of enteric infections. Finally, an encapsulated solution consisting of formic acid and citric acid, was used to control Enterobacteriaceae such as E. coli within the intestinal tract.
Table 1: Experimental design
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Experimental Diet |
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Stage |
Ingredients used |
Positive Control |
Treatment |
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Pre-starter (day 28-42) |
Zinc Oxide (ppm) β-glucan (g/ton) Bacillus sp. PB6 (CFU/kg) C Formic/citric acid (kg/ton) |
Basal diet 2500 ppm 0 0 0 |
Basal diet 0 300 2 x 108 4 |
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Starter (day 43-70) |
Zinc Oxide (ppm) β-glucan (g/ton) Bacillus sp. PB6 (CFU/kg) C Formic acid /citric (kg/ton) |
Basal diet 0 0 0 0 |
Basal diet 0 200 1 x 108 1 |
A total of 380 piglets (50% Large White x 25% Landrace x 25% Pietrain) were used in the trial over three batches. Piglets were balanced according to sex and weight then randomly allocated to either a Control or Treatment diet (Table 1). Each diet was replicated 9 times. Live weight and average daily weight gain (ADG) was measured. Faecal samples from the two first batches were collected and analysed for consistency. Faecal dry matter and pH were also analysed. Success criteria were defined as comparable outcomes in both experimental groups.
Figure 1: Piglet Average daily gain in the Control and Treatment group.
During the pre-starter phase (28-42 days), piglet ADG and live weight were similar in the Control diet supplemented with 2500 ppm of ZnO and in the Treatment group supplemented with algae β-(1,3)-glucan, Bacillus sp. PB6 and organic acids (P>0.05). The Median faecal diarrhoea score was also comparable and indicated normal faeces in both groups, which indicates that both strategies were able to prevent PWD. Faecal dry matter and pH analysis also showed similar results in both groups. Furthermore, the use of the three alternative ingredients improved piglet growth compared to the control diet during the starter period (43-70 d). Overall, the alternative strategy significantly improved the ADG (+4.5%) and the average piglet weight (+3%) compared to the ZnO diet (P<0.05) during the entire study period (28-70 d).
Reducing the dependency of pig farming on antibiotics is essential. Therefore, weaning piglets effectively without using antibiotics or high concentrations of ZnO is crucial, while still achieving the desired performance levels. This study's findings suggest a preventive health strategy incorporating algae β-(1,3)-glucans, Bacillus sp. PB6, and encapsulated formic and citric acid can replace pharmacological levels of zinc oxide without the need for antibiotics. This approach prevented post-weaning diarrhoea and maintained or even improved average daily gain throughout the study period.
