| In this study, in vitro batch culture was used to evaluate the effects of thiamine and oxythiamine on rumen fermentation and carbohydrate metabolism, and3×3Latin square experimental design was used in vivo experiment to evaluate the impact of thiamine on rumen microflora changes in case of Subacute ruminal acidosis (SARA) in cattles, and the results are showed as follows:Trial1Effects of Different Dietary Concentrate to Forage Ratios and Thiamine Supplement on Rumen Microbial Synthesis of Thiamine and Rumen FermentationIn this experiment, a subacute ruminal acidosis (SARA) model was established by gradually increasing the dietary concentrate levels of dairy cattles in vivo combined with in vitro culture, aimed at determining the effect of dietary concentrate levels on rumen thiamine synthesis, and the impacts of supplemental thiamine on rumen fermentation and microbial community under the state of SARA. A2×4two factorial design of an experiment was adopted: Factor one was different substrates with or without adding thiamin (0and180mg/kg), Factor two was different C:F (40:60,50:50,60:40,70:30), there were eight treatments and three replications in each treatment, samples were collected at Oh,3h,6h,9h,12h after culture in vitro. The results are showed as follows:The SARA model was established under the ratio of70:30, and with the increase of C:F, thiamine synthesis in culture medium first increased and then decreased, and thiamine content is significantly lower in the group cultured under the ratio of70:30than other treatment groups (P<0.05), which is-3.36μg/L at9h compared with Oh. The pH values significantly decreased with the increase of dietary concentrate levels (P<0.01), and the supplemental thiamine could retard the pH decreased significantly (P<0.01); There were significant effects of dietary concentrate levels and thiamine on lactate content in medium, at the period of3～12h, the lactate concentration of two groups cultured with the C:F of60:40and70:30were significantly higher than the other two groups (P<0.01). Trial2Effects of thiamine and its analogue oxythiamine on rumen fermentation and carbohydrate metabolism under Different Dietary Concentrate to Forage RatiosIn this part of study, In vitro batch culture and single factor design was used, aimed at researching the effects of thiamine (180mg/kg) and its analogue (Oxythiamine,400mg/kg) on rumen fermentation and enzyme activity of PDH under common and high concentrate diets. The results show that adding thiamine to the common diet led to an obvious increase of pH (9h, P<0.05) and a significant reduction of lactate concentration (9～12h, P<0.01), and thiamine has no significant effects on PDH activity under common diets (P>0.05); Conversely, oxythiamine tended to increase lactate content (6～12h, P<0.05) and decrease the enzyme activity of PDH significantly (9h, P<0.05).For high concentrate diets, adding thiamine would improve rumen fermentation through obviously raising rumen pH(9-12h, P<0.05), reducing lactate concentrate(3～9h, P<0.01) and enhancing PDH activity(P<0.05,16.31U/L vs15.80U/L,9～12h); While pH values decreased (9～12h, P<0.01) and lactate content increased significantly(3h,9h and12h, P<0.05;6h, P<0.01) in the test group added oxythiamine, and oxythiamine could markedly decrease PDH activity compared with other two groups(9～12h, P<0.01).No effects of thiamine and oxythiamine on the molar percent of acetic acid and propionic acid were found under both common diets and high concentrate diets, and also TVFA and ammonia-nitrogen concentration. While thiamine and oxythiamine tend to increase butyrate molar percent in high concentrate diets.Trial3Effects of Different Dietary Concentrate levels and Thiamine Supplement on the Changes of Microbial Community in Dairy CowsThree cows equipped with rumen cannula were randomly assigned to treatments in a3×3Latin square design with a21-d period. The three dietary treatments were:a common diet group (diets with40%concentrate level, NFC/NDF=1.19), a high-concentrate diet group (diets with70%concentrate level, NFC/NDF=2.30), and a high-concentrate diet group supplemented with thiamine at180mg/kg. Real time-PCR method was used to study the number of rumen bacteria. The results showed that SARA was conducted successfully when cows fed with high concentrate diets, adding thiamine could increase rumen pH and the difference was significant at9-12h after feeding (P<0.05); The population of Streptococcus bovis and lactobacillus of cows supplemented with high-concentrate diets were increased by3.62%and4.65%respectively(P<0.05) compared with common diets, while Butyrivibrio fibrisolvens and Megasphaera elsdenii were decreased by1.14%and4.90%(P<0.05) respectively, and Selenomonas ruminantium showed no signicant difference between two groups(P>0.05); Adding thiamine to high-concentrate diets led to an obvious reduction of Streptococcus bovis (P<0.05). However, Megasphaera elsdenii was improved dramaticly (P<0.05), there is no significant effects of thiamine on Butyrivibrio fibrisolvens, lactobacillus and Selenomonas ruminantium (P<.05). |
PDF Full Text Request