Role of dose-dependent Lactobacillus farciminis on ruminal microflora biogases and fermentation activities of three silage-based rations.

AIMS: The influence of Lactobacillus farciminis on ruminal fermentation characteristics was elucidated in this study. METHODS AND RESULTS: Ruminal fermentation was conducted using maize silage ration (R) and concentrate (C) as 75R:25C, 50R:50C and 25R:75C, supplemented with lactic acid bacteria (LB) at 0, 20 and 30 mg g-1 dry matter substrate and their interaction (1st experiment). The same LB product was used at 0, 20, 40 and 60 mg g-1 dry matter of the mixture (1 : 1) of oat straw and concentrate for 48 h of incubation (2nd experiment). At 24 and 48 h of incubation, LB0 produced the highest biogas and LB20 produced the lowest, whereas at 48 h of incubation LB40 produced the lowest. In ration x LB, LB40 resulted in the highest biogas production, while LB0 had the lowest (P < 0·001) at 8, 10 and 12 h of incubation. Inclusions of LB0, 20, 40 and 60 mg g-1 dry matter resulted in a linear increase (P < 0·003) in the asymptotic biogas production and fermentation parameters in a dose-dependent manner, except in pH which decreased (P = 0·029). CONCLUSIONS: The use of L. farciminis in diet with high level of concentrate without any adverse effect on the pH of rumen fluid to the point of acidosis. Furthermore, in high forage diet, the use of L. farciminis would help to improve the ruminal fermentation digestibility and mitigate ruminal biogas production. SIGNIFICANCE AND IMPACT OF THE STUDY: Using Lactobacillus as a feed additive can improve ruminal fermentation activities by maintaining the stability of pH in the rumen and improving the feed utilization through manipulation of the microbial ecosystem.

L-type Ca²âº channel activity determines modulation of GABA release by dopamine in the substantia nigra reticulata and the globus pallidus of the rat.

Modulation of L-type Ca²âº-channel function by dopamine is a major determinant of the rate of action potential firing by striatal medium spiny neurons. However, the role of these channels in modulating GABA release by nerve terminals in the basal ganglia is unknown. We found that depolarization-induced [³H]GABA release in both the substantia nigra reticulata and the external globus pallidus (GPe), was depressed by about 50% by either the selective L-channel dihydropyridine blocker nifedipine or the P/Q channel blocker ω-agatoxin TK. The effects of these blockers were additive and together eliminated about 90% of depolarization-induced [³H]GABA release. In addition, in the substantia nigra reticulata, dihydropyridines prevented both the stimulation of [³H]GABA release produced by dopamine D1 receptor activation and the inhibition caused by D4 receptor activation. In the GP nifedipine blocked the effects of D2 and A2(A) receptor coactivation as well as the effects of activating adenylyl cyclase with forskolin. ω-Agatoxin TK did not interfere with the action of these modulatory agents. The L-type Ca²âº-channel agonist BAYK 8644 stimulated GABA release in both substantia nigra reticulata and GP. Because dihydropyridine sensitivity is a key criterion to identify L-type Ca²âº-channel activity, our results imply that these channels are determinant of GABA release modulation by dopamine in striatonigral, striatopallidal and pallidonigral terminals.