Dose and time response of ruminally infused algae on rumen fermentation characteristics, biohydrogenation and Butyrivibrio group bacteria in goats

Abstract

Background: Micro-algae could inhibit the complete rumen BH of dietary 18-carbon unsaturated fatty acid (UFAs). This study aimed to examine dose and time responses of algae supplementation on rumen fermentation, biohydrogenation and Butyrivibrio group bacteria in goats.

Methods: Six goats were used in a repeated 3 × 3 Latin square design, and offered a fixed diet. Algae were infused through rumen cannule with 0 (Control), 6.1 (L-Alg), or 18.3 g (H-Alg) per day. Rumen contents were sampled on d 0, 3, 7, 14 and 20.

Results: H-Alg reduced total volatile fatty acid concentration and acetate molar proportion (P < 0.05), and increased propionate molar proportion (P < 0.05), whereas L-Alg had no effect on rumen fermentation. Changes in proportions of acetate and propionate in H-Alg were obvious from d 7 onwards and reached the largest differences with the control on d 14. Algae induced a dose-dependent decrease in 18:0 and increased trans-18:1 in the ruminal content (P < 0.05). H-Alg increased the concentrations of t9, t11-18:2 and t11, c15-18:2 (P < 0.05). L-Alg only seemed to induce a transient change in 18-carbon isomers, while H-Alg induced a rapid elevation, already obvious on d 3, concentrations of these fatty acid rose in some cases again on d 20. Algae had no effect on the abundances of Butyrivibrio spp. and Butyrivibrio proteoclasticus (P > 0.10), while H-Alg reduced the total bacteria abundance (P < 0.05). However, this was induced by a significant difference between control and H-Alg on d 14 (-4.43 %). Afterwards, both treatments did not differ as increased variation in the H-Alg repetitions, with in some cases a return of the bacterial abundance to the basal level (d 0).

Conclusions: Changes in rumen fermentation and 18-carbon UFAs metabolism in response to algae were related to the supplementation level, but there was no evidence of shift in ruminal biohydrogenation pathways towards t10-18:1. L-Alg mainly induced a transient effect on rumen biohydrogenation of 18-carbon UFAs, while H-Alg showed an acute inhibition and these effects were not associated with the known hydrogenating bacteria.

Keywords: Algae; Biohydrogenation; Goat; Hydrogenating bacteria.

Fig. 1

Changes in pH (a), TVFAs (b) (mmol/L) and molar proportions (%) of acetate (c), propionate (d) and butyrate (e) in goats fed diets with rumen infusion 0.0 g/d algae (Control, □), 6.1 g/d algae (L-Alg, ■), and 18.3 g/d algae (H-Alg, ▲)

Fig. 2

Changes in the concentrations (mg/g DM ruminal content) of 22:6 n-3 (a), t9, t12-18:2 (b), t11, c15-18:2 (c), c9, t11-CLA (d), t10, c12-CLA (e), t10-18:1 (f), t11-18:1 (g), c9-18:1 (h) and 18:0 (i) in goats fed diets with rumen infusion 0.0 g/d algae (Control, □), 6.1 g/d algae (L-Alg, ■), and 18.3 g/d algae (H-Alg, ▲)

Fig. 3

Changes in the abundance of total bacteria (a), Butyrivibrio spp. (b) and B. proteoclasticus (c) in goats fed diets with rumen infusion 0.0 g/d algae (Control, □), 6.1 g/d algae (L-Alg, ■), and 18.3 g/d algae (H-Alg, ▲)