Marine Macroalgae in Rabbit Nutrition: In Vitro Digestibility, Caecal Fermentability, and Microbial Inhibitory Activity of Seven Macroalgae Species from Galicia (NW Spain)

Abstract

The limitation on the prophylactic use of antibiotics in animal feed in Europe has critically challenged the rabbit meat industry, which urgently needs to find solutions. A feasible alternative could be using macroalgae in the diet to improve the gut health. This research studied seven species of marine macroalgae in four formats (dehydrated, enzymatically hydrolyzed, aqueous extract, and aqueous extract of hydrolyzed macroalgae) in order to select the most promising ones for their use in rabbit feed. Chemical composition, in vitro digestibility, in vitro caecal gas, total volatile fatty acid (VFA) production, and minimal inhibitory concentrations (MIC) against common pathogens were studied. All S. latissima products showed high caecal fermentability and VFA production, especially in both types of extracts. The H. elongata aqueous extract was remarkable due to its high in vitro butyrate production, which can be of great interest for improving gut health. The MIC results did not indicate any clear inhibition of the pathogens tested. The macroalgae tested appear to have a potentially prebiotic effect, rather than a direct antimicrobial activity. However, these results must be confirmed in vivo, in order to observe the real benefits of feeding macroalgae during the rabbit weaning period.

Elements in Serum, Muscle, Liver, and Kidney of Rabbits Fed Macroalgae-Supplemented Diets

“…In this trial, experimental diets, each including one of four macroalgae products, were tested. The macroalgae products were selected according to the results of their in vitro characterization [ 48 ] and the availability of discards from industrial processing. Based on these criteria, Saccharina latissima (sugar kelp) was tested in two formats: dehydrated macroalgae (SL) and an aqueous extract of the hydrolyzed macroalgae (ESL); Himanthalia elongata (sea spaghetti) was tested as an aqueous extract (EHE), and Ulva spp.…”

“…The products were provided by Porto-Muíños S.L. (Cerceda, A Coruña, Spain) and elaborated from discards generated during industrial processing, as previously described [ 48 ]. The basal growing diet ( Table 2 ), formulated according to the nutrition standards for growing rabbits, was supplemented with macroalgae products at a concentration of 1.025% (dry matter).…”