Alternatives to antibiotics and trace elements (copper and zinc) to improve gut health and zootechnical parameters in piglets: A review

The weaning period is a critical stage in pig production and the use of antibiotics and high concentrations of trace elements (copper and zinc) have proved to be very effective at reducing the economic impact of the post weaning diarrhoea that occurs during the first two weeks after weaning. However, the overuse of these substances has led to the development of bacterial resistance and accumulation in the environment, and thus has forced the pig/feed industry to search for alternatives. This paper presents a comprehensive review of the experimental data published in the scientific literature in the last decade focused on the alternatives to antibiotics/trace elements to improve gut health and growth performance in piglets. The diet appeared as the keystone to improve gut health and zootechnical parameters in weaned piglets. The critical points are the reduction of the protein content, the use of highly digestible protein sources to avoid undesirable fermentation of proteins in the hindgut, and the optimisation of the intake of different types of carbohydrates, mainly fibre. A large variety of feed additives were also examined, including probiotics, prebiotics, amino acids, enzymes, organic acids, plants extracts/essential oils, seaweed/seaweed extracts, nucleotides and antimicrobial peptides. The effects of these feed additives on gut health and the growth performance were tested, in most cases, against a commercial control diet, having shown promising results. The few studies that included a comparison of feed additives with a positive control diet, including antibiotics or trace elements (mainly zinc oxide), did not generally show statistically significant differences in gut health and growth performance parameters, which leads to suggest on their potential as alternatives to antibiotics/trace elements. The greatest uncertainties were found for probiotics and prebiotics, where no generalized conclusions can be drawn about their efficacy, as studies showed quite unsteady results. Moreover, the mechanisms responsible for the feed additive's growth promotion effects are far from being completely known and pivotal data on the complex homeostasis of the gut are still lacking. This information would be essential when combining more than one dietary alternative with different mode of actions. Finally, some of these substances (for example amino acids) exert their effects on gut health at higher concentrations than in standard diets and the effective dose as well as the possible interactions with other feed ingredients/additives (particularly probiotics, prebiotics and organic acids) need further research

Safety and efficacy of selenium‐enriched yeast (Saccharomyces cerevisiae CNCM I‐3399) for all animal species

Abstract Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of selenium‐enriched yeast (Saccharomyces cerevisiae CNCM I‐3399) for all animal species, based on a dossier submitted for the modification of the terms of authorisation of the additive. The additive is currently authorised as selenomethionine produced by S. cerevisiae CNCM I‐3399 as a nutritional additive (compound of trace elements) with a minimum selenium content of 2,000 mg/kg. The applicant proposed the inclusion of an additional formulation with a minimum content of selenium in the additive of 3,000 mg/kg. Considering (i) that there are no relevant changes in the manufacturing of the product compared to the former application and (ii) that the conditions of use already authorised remain the same, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) stated that the modification requested would not affect the conclusions of the FEEDAP Panel on safety for the consumer, safety for the environment and efficacy of the product made in a previous assessment of a similar product with a lower selenium concentration. Since the capacity of the additive to homogeneously distribute in feed was proven, the tolerance studies already provided for the currently authorised product could be used to conclude on the safety of the additive for the target animals. Selenium is hazardous upon inhalation; owing to the dusting potential and the selenium content of dust, persons handling the additive are at risk. The additive should be considered as a respiratory sensitiser. The additive is not an irritant for eyes and skin. No conclusions can be reached on the dermal sensitising properties of the additive