Fermented soybean meal affects the ruminal fermentation and the abundance of selected bacterial species in Holstein calves: a multilevel analysis

Abstract

The effect of soybean meal (SBM) replacement with fermented SBM (FSBM) on ruminal fermentation and bacterial abundance in Holstein calves was investigated in this study. Thirty nine calves were randomized to: (1) control: 27% SBM + 0% FSBM (FSBM0, n = 13); (2) 18% SBM + 9% FSBM (FSBM9, n = 13); and (3) 13.5% SBM + 13.5% FSBM (FSBM13, n = 13). SBM contained a greater amount of large peptides containing 3 to 10 amino acids (AAs), while FSBM had a greater amount of ammonia nitrogen (NH 3-N), free AAs, and small peptides containing 2 to 3 AAs. The calves fed FSBM13 had the lowest acetic acid, NH 3-N, and the ratio of acetate to propionate, with the greatest concentration of caproic acid, valeric acid and isovaleric acid in ruminal fluid. Compared to those fed FSBM9 or FSBM13, the calves fed FSBM0 had the greatest proportion of Butyrivibrio fibrisolvens and Ruminococcus albus in rumen fluid. However, the ruminal abundance of Prevotella ruminicola in calves fed FSBM13 was greater than in calves fed FSBM0. Network analysis showed that the abundance of the Ruminococcus albus was associated with large peptides, and butyric acid was correlated with small peptide. Taken together, our findings suggest that FSBM may have the potential to boost calf performance by changing the fermentation products and the relative abundance of some members of the bacterial community in the rumen. The calf starts its life with a physically and metabolically undeveloped rumen. Calves generally experience significant changes not only in the development of their rumen, but also in the rumen bacterial composition and community 1. This, in turn, enables calves to digest dry feeds for their growth needs, impacting productivity and future milk production capacity 1,2. Fibrolytic bacteria are important for the rapid anatomical and physiological growth of rumen, as the newborn calf moves from a liquid diet (i.e., milk) to a solid diet, such as grass and hay 3. Rumen microbes are classified into various functional groups, for example cellulolytic, amylolytic and proteolytic bacteria species 4. These organisms metabolize feed components and other microbial products 5. The rumen microbial community and the functional development of the stomach are affected by diets 4. For example, when forages are fed to ruminants, Bacteroidales and Ruminococcaceae become dominant 4. On the other hand, it is known that animals fed high-concentrate diets have more Prevotella and Succinivibrionaceae in their rumen fluid 4,6-8. Therefore, diets fed to animals can alter the relative abundance of bacteria and the profile of volatile fatty acids (VFAs) in the rumen 1,4. This, in turn, affects the evolution of the early ruminal development and microbiota 9 .

Fermented Soybean Meal Replacement in the Diet of Lactating Holstein Dairy Cows: Modulated Rumen Fermentation and Ruminal Microflora

“…As was revealed in the results of the current trial, replacing SBM with FSBM significantly decreased the TVFA concentration and the molar ratio of butyrate, while tended to reduce the acetate molar proportion. Similarly, Feizi et al (2020) found that the substitution of FSBM for SBM at 30 and 50% both significantly lowered the molar ratio of acetate in the rumen fluid of Holstein calves, while the molar proportion of butyrate tended to be less in the calves fed the starter in which SBM was replaced by FSBM at 30%. This phenomenon could be explained by the greater quantity of RUP in FSBM (Stein et al, 2008;Rezazadeh et al, 2019), as it has been reported that the TVFA production and the molar percentages of acetate and butyrate was lessened in response to the existence of RUP in a dual-flow continuous culture system using rumen contents obtained from Holstein cattle (Griswold et al, 1996).…”

“…In the current study, results showed that entirely replacing SBM with FSBM in the diet for lactating Holstein dairy cows did not affect the ruminal pH or the NH 3 -N concentration. However, Feizi et al (2020) concluded that the substitution of FSBM for SBM at 50% in the starter diet raised the level of NH 3 -N in the rumen fluid of Holstein calves in a previous study, in which the ruminal pH was not measured. This inconsistency can be attributed to the differences in the animals, composition of experimental rations, and contents of FSBMs, and further research is required.…”

“…In contrast to the SBM, it is acknowledged that FSBM is more preferred as a protein source for domestic ruminants since it could be characterized by the less amount of anti-nutritional agents, greater content of non-protein nitrogen (i.e., small peptides, free amino acids, and ammonia), and increased quantity of RUP (Zhang et al, 2013;Feizi et al, 2020;Wang et al, 2020a). Nonetheless, so far, most of the preceding investigations on the impacts of applying FSBM in dairy cattle have concentrated on the growth performance and immune response of young calves, while few have explored the effects of FSBM on the rumen fermentation and the ruminal bacterial microflora of lactating dairy cows (Kim et al, 2010(Kim et al, , 2012Kwon et al, 2011;Rezazadeh et al, 2019).…”

“…Previous investigations have found that antinutritional factors might be eliminated or reduced through microbial fermentation of soybean meal (Feng et al, 2007;Wang et al, 2020a). Besides, it has been demonstrated that the fermentation process of soybean meal enhances the amount of non-protein nitrogen including small peptides, free amino acids, and ammonia (Feizi et al, 2020). Furthermore, the RUP content could also be elevated in fermented soybean meal (FSBM), possibly due to intensive heat processing before fermentation treatment (Stein et al, 2008).…”

“…It was further illustrated that apart from the alleviated weaning stress through the reduction of pro-inflammatory mediators, the growth performance was also enhanced by providing abruptly weaned Holstein calves with FSBM during cold weather (Rezazadeh et al, 2019). Subsequently, Feizi et al (2020) concluded that substituting SBM with FSBM might promote the performance of calves by altering rumen fermentation products, as well as the relative abundance of specific ruminal bacteria. In contrast, information on the influences of dietary FSBM replacement in the lactating dairy cattle is rare.…”