Comparison of the effect of sodium bicarbonate buffer with Megasphaera elsdenii as a rumen-consuming acid on growth performance, digestibility, rumen and blood parameters of lambs in high concentrate

Introduction: The feeding of high fermentable carbohydrates in ruminants resulted in producing high amounts of organic acids in the rumen, followed by a decrease in rumen pH. In the animals not adapted to high levels of carbohydrate fermentation, rumen lactate concentrations increase unacceptably, because populations of lactate-utilizing bacteria such as Selenomonas ruminantium and Megasphaera elsdenii are low and cannot rapidly match and their proliferation need more time (Chaucheyras-Durand et al., 2008). It has been suggested that Saccharomyces cerevisiae can expand the population of Megasphaera elsdenii and increase lactate utilization (Calsamiglia et al., 2012). The use of yeast and bioactive compounds compared to the chemicals can be effective in reducing inflammation caused by acidosis (Aschenbach et al., 2019).
Material and methods: Twenty-four Arabic male lambs with Four months old and initial body weight of 23.9±3.15 kg were used in a completely randomized design with three treatments and eight replicates. The trial period consisted of 77 days (11 weeks) including 14 days of habituation period and 63 days (9 weeks) of recording period. The lambs were randomly assigned to one of three treatments: 1-control (no additive) 2-control + Sodium bicarbonate (1% daily diet in two meals) 3-control + Megasphaera elsdenii and Saccharomyces cerevisiae (bacterial-yeast). The amount of Megasphaera elsdenii was 3 ml per animal (4.5 × 108 cfu / ml) plus 2 g of Saccharomyces cerevisiae (7 × 10 9 cfu/g) (DFM) fed to the animals daily in the morning (Sedighi and Alipour, 2019). The diets were adjusted using the Small Ruminants Nutrition Requirements (NRC, 2007). The lambs were fed a fully mixed (TMR) ratio of 30% forage and 70% concentrate at two meals (8 and 16 hours) with free access to water. Ruminal fluid was taken by stomach tube at 0, 3 and 6 hours after morning feeding to measure pH and ammonia nitrogen (NH3-N) concentration. The ruminal fluid was analyzed for ammonia-N using a phenol-hypochlorite method (Broderick and Kang, 1980). On the last day of the experiment, rumen fluid was taken to measure the concentration of volatile fatty acids (5 ml of rumen fluid with 2 ml of 25% acid metaphosphoric acid (W / V) was mixed and stored at -20 ° C until analysis). Blood sampling were taken from each lamb within 3 h after the morning feeding from the jugular vein, and used EDTA as anticoagulant. Blood samples were analysed for glucose, blood urea nitrogen (BUN), total protein, cholesterol, triglycerides, LDL, HDL, creatinine and liver enzymes including aspartate amino transaminase (AST) and alanine aminotransferase (ALT). During the last 7 days of the period, total faeces and urine samples were collected to determine digestibility and nitrogen retention.
Results and discussion: No differences were observed between treatments in dry matter intake (DMI), daily weight gain (ADG), feed conversion ratio, pH and ammonia nitrogen (NH3 – N) (P > 0.05). Propionate concentration was higher in the bacteria-yeast treatment than other treatments (P <0.05). Megasphaera elsdenii is the only known rumen microorganism that can convert lactate to propionate by the acrylate pathway; when the lactate concentration increases, produces propionate and acetate and sometimes butyrate from it (Prabhu et al., 2012). Protein digestibility was higher in control and bacteria-yeast treatments than in buffer treatment (P <0.05). Low-density lipoprotein (LDL) was lower in buffer and bacteria-yeast treatments than in control treatment (P <0.05). Nitrogen retention was higher in the bacteria-yeast treatment than in the other treatments (P <0.05). Significance of nitrogen retention in the bacterial-yeast recipient treatment can be attributed to the decrease in ruminal ammonia nitrogen concentration, which appears to be due to increased nitrogen incorporation in the microbial protein, which is a logical consequence of increased rumen microbial activity (Paryad and Rashidi, 2009).
Conclusion: The use of acid-consuming bacteria, can be an effective way to modify rumen fermentation conditions of lambs fed with high concentrate diets and in the present experiment, its effect was competitive with the sodium bicarbonate chemical buffer on nutrient digestion and growth performance. Results from volatile fatty acids showed that bacteria-yeast treatments by leading the fermentation pathway to convert lactate to propionate could be beneficial for livestock health and its economic longevity.
Results and discussion: No differences were observed between treatments in dry matter intake (DMI), daily weight gain (ADG), feed conversion ratio, pH and ammonia nitrogen (NH3 – N) (P > 0.05). Propionate concentration was higher in the bacteria-yeast treatment than other treatments (P <0.05). Megasphaera elsdenii is the only known rumen microorganism that can convert lactate to propionate by the acrylate pathway; when the lactate concentration increases, produces propionate and acetate and sometimes butyrate from it (Prabhu et al., 2012). Protein digestibility was higher in control and bacteria-yeast treatments than in buffer treatment (P <0.05). Low-density lipoprotein (LDL) was lower in buffer and bacteria-yeast treatments than in control treatment (P <0.05). Nitrogen retention was higher in the bacteria-yeast treatment than in the other treatments (P <0.05). Significance of nitrogen retention in the bacterial-yeast recipient treatment can be attributed to the decrease in ruminal ammonia nitrogen concentration, which appears to be due to increased nitrogen incorporation in the microbial protein, which is a logical consequence of increased rumen microbial activity (Paryad and Rashidi, 2009).
Conclusion: The use of acid-consuming bacteria, can be an effective way to modify rumen fermentation conditions of lambs fed with high concentrate diets and in the present experiment, its effect was competitive with the sodium bicarbonate chemical buffer on nutrient digestion and growth performance. Results from volatile fatty acids showed that bacteria-yeast treatments by leading the fermentation pathway to convert lactate to propionate could be beneficial for livestock health and its economic longevity.