DietaryChlorella vulgarismicroalgae improves feed utilization, milk production and concentrations of conjugated linoleic acids in the milk of Damascus goats

SUMMARYFifteen lactating Damascus goats (44 ± 0·8 kg body weight) were used in a completely randomized design to evaluate the supplementation ofChlorella vulgarismicroalgae at 0 (Control), 5 (Alg05) and 10 g/goat/day (Alg10) for 12 weeks.Chlorella vulgaristreatments increased feed intake and apparent diet digestibility compared with a control diet. No differences were noted in the ruminal pH and ammonia-N concentrations, but increased concentration of total volatile fatty acids and propionic acid were observed in goats fed with Alg05 and Alg10. Diets of Alg05 and Alg10 increased serum glucose concentration but decreased glutamate-oxaloacetate transaminase, glutamate-pyruvate transaminase and cholesterol concentrations. Additionally,C. vulgarissupplementation moderately increased milk yield, energy corrected milk, total solids, solids not fat and lactose. Feeding Alg05 and Alg10 diets increased milk unsaturated fatty acids with concomitant increases in total conjugated linoleic acid concentrations. It is concluded that the daily inclusion of 5 or 10 g ofC. vulgarisin the diets of Damascus goats increased milk yield and positively modified milk fatty acid profile.

Ruminal biohydrogenation as affected by tanninsin vitro

The aim of the present work was to study the effects of tannins from carob (CT;Ceratonia siliqua), acacia leaves (AT;Acacia cyanophylla) and quebracho (QT;Schinopsis lorentzii) on ruminal biohydrogenationin vitro.The tannins extracted from CT, AT and QT were incubated for 12 h in glass syringes in cow buffered ruminal fluid (BRF) with hay or hay plus concentrate as a substrate. Within each feed, three concentrations of tannins were used (0·0, 0·6 and 1·0 mg/ml BRF). The branched-chain volatile fatty acids, the branched-chain fatty acids and the microbial protein concentration were reduced (P < 0·05) by tannins. In the tannin-containing fermenters, vaccenic acid was accumulated (+23 %,P < 0·01) while stearic acid was reduced ( − 16 %,P < 0·0005). The concentration of total conjugated linoleic acid (CLA) isomers in the BRF was not affected by tannins. The assay on linoleic acid isomerase (LA-I) showed that the enzyme activity (nmol CLA produced/min per mg protein) was unaffected by the inclusion of tannins in the fermenters. However, the CLA produced by LA-I (nmol/ml per min) was lower in the presence of tannins. These results suggest that tannins reduce ruminal biohydrogenation through the inhibition of the activity of ruminal micro-organisms.