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The increasing demand for animal protein by the growing world population intensifies the exploration of novel feed sources. This study evaluated the nutritional value of six intact seaweed species (i.e. the brown species Saccharina latissima, Laminaria digitata, and Ascophyllum nodossum, the red species Palmaria palmata, and Chondrus crispus and green species Ulva lactuca), collected from the coast of Ireland, Scotland and France as an ingredient for animal feed. The nutrient composition, in vitro digestibility, and in vitro gas production simulating rumen fermentation, were determined. The nutrient contents (g/kg dry matter), both between and within species, were highly variable, ranging from 45–248 for crude protein, 351–691 for non-starch polysaccharides, and 173–445 for ash. Overall, the brown seaweeds had the highest non-starch polysaccharides content, whereas samples of the red and green seaweeds had an amino acid content up to 265 g/kg dry matter. All samples had a substantial non-protein nitrogen fraction, varying from 0.12–0.29 of nitrogen. The fibre fractions of brown seaweeds showed different properties than land-based plants, as illustrated by a lower analysed neutral detergent fibre than acid detergent fibre content. The ileal organic matter and nitrogen digestibility, as well as the total tract organic matter digestibility (mean digestibility coefficients: 0.81, 0.89 and 0.88, respectively) were lower for all seaweeds compared to soybean meal (digestibility coefficients: 0.84, 0.98 and 0.97, respectively). S. latissima, L digitata, P. palmata and U. lactuca had a higher maximum gas production than alfalfa, but lower than sugar beet pulp. Based on the protein content and amino acid-pattern, intact P. palmata and U. lactuca would be a valuable protein source for farm animals, with the high non-starch polysaccharides and non-protein nitrogen contents and a low in vitro digestibility potentially limiting their use as a feed ingredient for monogastric species. The fermentability of L. digitata, S. latissima and P. palmata indicate that these intact seaweeds may have a higher nutritional value in ruminants. The high ash content in all seaweed species hampers the use of intact seaweed for both ruminants and monogastrics. Extraction of protein and other favourable components, while reducing the ash content, seems an important step towards seaweed inclusion in animal diets. Further identification and characterisation of seaweed polysaccharides is required to understand and improve the digestibility of seaweed fractions.

The use of seaweed as feed ingredient is gaining interest but the high ash content, low nutrient digestibility, short shelf life and poor economic feasibility hamper practical application. This study investigates the effect of washing, ensiling and extraction processes on the nutritional value of seaweed products for broilers, based on nutrient content and in vitro and in vivo digestibility. The effects of ensiling, washing and extraction processes were evaluated using Saccharina latissima, Laminaria digitata and Ulva lactuca, with 2, 4, and 6 h incubations in an in vitro simulated digestibility model, to obtain insight into the kinetics of digestibility. In an in vivo study, 160 Ross 308 male broilers were fed (day 14–22) a basal grower diet, or the basal grower diet with 100 g/kg of S. latissima silage or silage residue. Performance and ileal and total tract nutrient digestibility were determined. Washing and ensiling reduced the ash content, but also the in vitro organic matter digestibility (both P < 0.001). Washing also reduced nitrogen digestibility (P < 0.001). Extraction of seaweed decreased in vitro organic matter and nitrogen digestibility. Feeding seaweed diets to broilers resulted in a higher feed conversion ratio (1.62 versus 1.86 and 1.77 for broilers fed the basal, silage and silage residue diets respectively, P < 0.001) without increase in final body weight. Feeding S. latissima silage residue compared to silage resulted in a slightly better broiler performance and a higher amino acid digestibility. In conclusion, washing, ensiling and extraction processes reduce the nutritional value of the seaweed products, and do not make seaweed suitable for inclusion in broiler diets. To create suitable seaweed products for inclusion in broiler diets, a further reduction in the ash content and increase in digestibility is needed.

The current study was conducted to evaluate the effect of feed supplementation with a phytogenic product (equal mixture of thymol plus carvacrol; T+C) on performance, nutrient retention, volatile fatty acid (VFA) profiles, cecum microbial ecosystem, serum parameters and characteristics of gastrointestinal tract of broilers fed on wheat-based diets with or without an NSP-degrading enzyme product (xylanase plus β-glucanase; E) from d 0 to 42. Six dietary treatments were arranged according to a factorial design with three levels of T+C (0, 100 and 200. mg/kg of diet) and two levels of E (0 and 0.5 g/kg of diet). Each treatment was replicated five times with 12 chicks per replicate. There was no interaction effect between E and T+C on any of the measured parameters. Compared with the control group, birds fed diets containing E or T+C had a higher ( P

Three in vitro experiments were carried out to determine the effect of temperature, moisture content, duration of incubation, Ca level, soaking with water or citric acid onphytate degradation in a wheat–barley–rye–soybean meal-based broiler diet. In experiment 1, phytase activity of individual feed ingredients and 4 low-P broiler diets, containing 2, 4, 8, and 12 g Ca per kg diet, respectively, were measured in the presence or absence of sodium phytate or soybean meal. By using sodium phytate as substrate, phytase activity of rye, wheat, barley and soybean meal was 3350, 1170, 580 and 30 FTU/kg, respectively (P 0.05). In experiment 2, the effect of 2 moisture levels (0.25 and 50%), 3 temperatures (70, 75 and 80 C) and 3 durations of incubation (2, 4, and 8 min) on the residual phytase activity of diet 1 (basal diet) were evaluated as a 2 × 3 × 3 factorial arrangement with 3 replicates per treatment. The loss of activity of intrinsic phytase increased from 0.25 at 70 C to 0.61 at 80 C (P In conclusion, soaking of a broiler diet, especially in a citric acid solution one day before feeding, may increase available P and decrease the need of supplemental inorganic P to these diets, thus improving the sustainable use of P resources.