Effects of Suaeda glauca crushed seed on rumen microbial populations, ruminal fermentation, methane emission, and growth performance in Ujumqin lambs

• Addition of Suaeda glauca seed increased growth rate of lambs.
• Addition of Suaeda glauca seed reduced methane emission from lambs.
• Addition of Suaeda glauca seed reduced methanogenic bacterial populations in lambs.

This study was conducted to evaluate the effects of Suaeda glauca crushed seed on rumen microbial populations, ruminal fermentation, methane emission, and growth performance in lambs. Thirty male Ujumqin lambs (a local breed, average body weight 25.5 ± 1.28 kg) were equally divided into three treatments for a 56 d feeding period. The treatments were control diet (CTR), 80 g of SG seed/kg of diet (SGS80, dry matter (DM) basis), and 160 g of SG seed/kg of diet (SGS160, DM basis). Ruminal samples were collected at 0, 3, 6 and 9 h after the morning feeding on d 28 and 56 to investigate treatment, sampling day, sampling hour, and their interactions effects on ruminal parameters and microorganism population. After the feeding trial, all lambs were moved to respiratory chambers to measure methane emission. Addition of SG seed decreased methanogen (P < 0.05), protozoa (P < 0.01), and Fibrobacter succinogenes populations (P < 0.05). Methanogen and protozoa populations were also affected by an interaction between treatment and sampling day (P < 0.01) and the effect of SG seed on methanogen and protozoa populations decreased with feeding time. Addition of SG seed did not change populations of fungi, Ruminococcus flavefaciens, and Ruminococcus albus. Lambs fed SG160 diet had lower rumen ammonia nitrogen concentration (P < 0.01) compared with lambs fed CTR diet. Ammonia nitrogen concentration was affected by an interaction between treatment and sampling day (P < 0.01). No SG seed effects were found in ruminal pH, total volatile fatty acid concentration and molar proportion of volatile fatty acid. Addition of SG seed increased average daily gain (P < 0.05) and dry matter intake (P < 0.05) of lambs but reduced methane emissions (P < 0.05). No SG seed effects were found in feed efficiency. In conclusion, addition of SG seed seemed to be a feasible means of decreasing methane emissions from lambs by reducing methanogen and protozoa populations.