Effect of dietary supplementation with essential oils and a Bacillus probiotic on growth performance, diarrhoea and blood metabolites in weaned pigs

Abstract

Context: Dietary supplementation of essential oils or in combination with a Bacillus probiotic was investigated as an antibiotic growth promoter for weaned pigs. Aims: To evaluate the effect of essential oils (i.e. thymol and carvacrol mixture) or in combination with a probiotic strain (i.e. Bacillus subtilis PB6) on the growth performance, diarrhoea incidence, ammonia emission and serological profiles of weaned pigs. Methods: A total of 96 crossbred ([Yorkshire × Landrace] × Duroc) weaned pigs were randomly allotted to one of six treatments based on sex and initial bodyweight. Each group was distributed into four replicates with four pigs each according to a randomised complete block design. The treatments were: (i) positive control, basal diet supplemented with colistin 150 g/tonne and amoxicillin 200 g/tonne (ii) negative control, basal diet without supplementation (iii) T3, basal diet supplemented with essential oils 300 g/tonne (iv) T4, basal diet supplemented with essential oils 600 g/tonne (v) T5, basal diet supplemented with essential oils 1000 g/tonne and (vi) T6, basal diet supplemented with essential oils 300 g/tonne diet and Bacillus probiotics 1000 g/tonne. Key results: The piglets fed with supplements had a significantly higher average daily gain and lower incidence of diarrhoea than the piglets in the negative control (P = 0.001). Feeding the essential oils alone or in combination with probiotics significantly reduced faecal ammonia emission (P = 0.027) and blood urea nitrogen (P = 0.039), while markedly increasing the serum immunoglobulin G concentration of weaned pigs compared with the negative control treatment (P = 0.014). The difference in time of blood collection had significant effects on blood urea nitrogen and immunoglobulins (P = 0.001). However, no significant differences emerged in average daily feed intake, gain: feed ratio, feed efficiency and antibody against swine fever among the treatments. Conclusions: Diet supplementation with essential oils or in combination with probiotics improved growth performance and immunity, and lowered ammonia emissions and diarrhoea incidence of weaned pigs. Implications: These findings provide a basis for the application of phytogenic compounds and probiotics as antibiotic growth promoter alternatives in post-weaning diets for pigs.