Abstract
Improvement of the food value of rice straw is urgently required in rice crop growing areas to mitigate pollution caused by rice straw burning and enhance the supply of high-quality forages for ruminants. The aims of the present study were to compare the effects of fresh corn Stover and rice straw co-fermented with probiotics and enzymes on rumen fermentation and establish the feasibility of increasing the rice straw content in ruminant diets and, by extension, reducing air pollution caused by burning rice straw. Twenty Simmental hybrid beef cattle were randomly allotted to two groups with ten cattle per group. They were fed diets based either on rice straw co-fermented with probiotics and enzymes or fresh corn Stover for 90 days. Rumen fluid was sampled with an esophageal tube vacuum pump device from each animal on the mornings of days 30, 60, and 90. Bacterial diversity was evaluated by sequencing the V4–V5 region of the 16S rRNA gene. Metabolomes were analyzed by gas chromatography/time-of-flight mass spectrometry (GC–TOF/MS). Compared to cattle fed fresh corn Stover, those fed rice straw co-fermented with probiotics and enzymes had higher (P < 0.05) levels of acetic acid and propionate in rumen liquid at d 60 and d 90 respectively, higher (P < 0.05) abundances of the phyla Bacteroidetes and Fibrobacteres and the genera Ruminococcus, Saccharofermentans, Pseudobutyrivibrio, Treponema, Lachnoclostridium, and Ruminobacter, and higher (P < 0.05) concentrations of metabolites involved in metabolisms of amino acid, carbohydrate, and cofactors and vitamins. Relative to fresh corn Stover, rice straw co-fermented with probiotics and enzymes resulted in higher VFA concentrations, numbers of complex carbohydrate-decomposing and H2-utilizing bacteria, and feed energy conversion efficiency in the rumen.
Highlights
It is of great significance to vigorously develop ruminant production in the main grain producing areas to increase the amount of crop straw in ruminant diet, reduce the pollution caused by crop straw burning, and increase the income of farmers and herdsmen
Kg in fermented rice straw group and (7.85 ± 0.10) kg in fresh corn Stover group, respectively, and no significant difference was observed between two groups (P = 0.433)
Data showed that the cuticle wax silica layer on straw may be removed by fermentation with Streptomyces griseorubens C-530 and lignocellulose can be hydrolyzed by acetic acid t reatment[31]
Summary
It is of great significance to vigorously develop ruminant production in the main grain producing areas to increase the amount of crop straw in ruminant diet, reduce the pollution caused by crop straw burning, and increase the income of farmers and herdsmen. The key problem to be solved is how to improve the effective fermentation of crop straw and reduce the formation of methane in the rumen while using crop straw to develop ruminant production. If ruminants could more efficiently utilize rice straw as a roughage source, feed shortages and air pollution from rice straw burning and methane emission could be substantially mitigated. Compared with corn Stover, rice straw has lower nutrient digestibility in the rumen as it has a thick outer cuticle-wax silica-layer and high lignin content[12,13]. For this reason, rice straw is usually burned instead of being used as the main constituent of ruminant diets. Rumen fluid samples were collected to (1) compare rumen fermentation characteristics in cattle fed fermented rice straw with those fed fresh corn Stover; (2) investigate the differences in the compositions of H2-producing and utilizing bacteria and metabolites of the rumen fluid of cattle fed fermented rice straw with those fed fresh corn Stover; and (3) explore the relationship between the differential bacteria and differential metabolites in rumen fluid
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
