Variability and Potential of Seaweeds as Ingredients of Ruminant Diets: An In Vitro Study

Abstract

Simple SummaryThe use of seaweeds as ingredients of ruminant diets can be an alternative to conventional feedstuffs, but it is necessary to assess their nutritive value. The aim of this study was to analyze the chemical composition and in vitro rumen fermentation of eight brown, red and green seaweed species collected in Norway during both spring and autumn. The in vitro ruminal fermentation characteristics of 17 diets composed of oat hay:concentrate in a 1:1 ratio, with the concentrate containing no seaweed or including one of the 16 seaweed samples, was also studied. Species and season determined differences in chemical composition and in vitro fermentation of seaweeds. Most of the tested seaweeds can be included in the diet (up to 200 g/kg concentrate) without negative effects on in vitro ruminal fermentation.AbstractThis study was designed to analyze the chemical composition and in vitro rumen fermentation of eight seaweed species (Brown: Alaria esculenta, Laminaria digitata, Pelvetia canaliculata, Saccharina latissima; Red: Mastocarpus stellatus, Palmaria palmata and Porphyra sp.; Green: Cladophora rupestris) collected in Norway during spring and autumn. Moreover, the in vitro ruminal fermentation of seventeen diets composed of 1:1 oat hay:concentrate, without (control diet) or including seaweeds was studied. The ash and N contents were greater (p < 0.001) in seaweeds collected during spring than in autumn, but autumn-seaweeds had greater total extractable polyphenols. Nitrogen in red and green seaweeds was greater than 2.20 and in brown seaweeds, it was lower than 1.92 g/kg DM. Degradability after 24 h of fermentation was greater in spring seaweeds than in autumn, with Palmaria palmata showing the greatest value and Pelvetia canaliculata the lowest. Seaweeds differed in their fermentation pattern, and autumn Alaria esculenta, Laminaria digitata, Saccharina latissima and Palmaria palmata were similar to high-starch feeds. The inclusion of seaweeds in the concentrate of a diet up to 200 g/kg concentrate produced only subtle effects on in vitro ruminal fermentation.

Ruminal Fermentation, Growth Rate and Methane Production in Sheep Fed Diets Including White Clover, Soybean Meal or Porphyra sp.

“…There were no differences among diets in total VFA production or in VFA profile. In contrast to De la Moneda et al [19], the POR diet did not differ from the CON diet in VFA profile or the acetate/propionate ratio. Compared with the Porphyra diet used by De la Moneda et al [19], the total VFA production in the POR diet was lower.…”

“…In contrast to De la Moneda et al [19], the POR diet did not differ from the CON diet in VFA profile or the acetate/propionate ratio. Compared with the Porphyra diet used by De la Moneda et al [19], the total VFA production in the POR diet was lower. However, the molar proportions of the individual VFA were similar to De la Moneda et al [19], although the acetate/propionate ratio was slightly lower for POR (2.62 mol/mol) compared to [19] (3.2 mol/mol).…”

“…In the present study, no differences in total gas production (A), c or AGPR were found. This is comparable to results by De la Moneda et al [19], who found that diets including Porphyra sp. did not reduce the extent of fermentation compared to a control diet.…”

“…Compared with the Porphyra diet used by De la Moneda et al [19], the total VFA production in the POR diet was lower. However, the molar proportions of the individual VFA were similar to De la Moneda et al [19], although the acetate/propionate ratio was slightly lower for POR (2.62 mol/mol) compared to [19] (3.2 mol/mol). The lack of differences in NH 3 concentration between diets also indicates similar protein degradability.…”

“…In vitro and in situ techniques are used in animal nutrition research as they are less expensive, time-consuming and laborious compared to in vivo experiments. There are some in vitro and in situ studies investigating the nutritive value of seaweeds [7][8][9]19] but, to our knowledge, very few in vivo experiments have been performed using seaweed as a protein source for ruminants [12,20,21]. Also, we have no knowledge of in vivo experiments including Porphyra sp.…”