An rRNA-based analysis for evaluating the effect of heat stress on the rumen microbial composition of Holstein heifers.

We performed a set of heifer feeding trials to investigate the effect of heat and humidity stresses on the rumen bacterial molecular diversity of Holstein heifers (Tajima K, Nonaka I, Higuchi K, Takusari N, Kurihara M, Takenaka A, et al. Anaerobe 2007;13:57-64). To further characterize the response of the microbial community to the physiological changes caused by the stresses, we evaluated changes in the ruminal bacterial community composition in the same trials by applying an RNA-based method (sequence-specific small-subunit (SSU) rRNA cleavage method), which was optimized for a comprehensive description of the predominant bacterial groups inhabiting the rumen. Four Holstein heifers were kept at three temperatures (20 degrees C, 28 degrees C, 33 degrees C) in a climatic chamber for two weeks each, and rumen fluid samples were obtained on the last day of each temperature experiment. For quantitative detection, we applied a set of 15 oligonucleotide probes, including those targeting taxa comprised of uncultured rumen bacteria (URB) belonging to phylum Firmicutes, to the RNAs extracted from the fluid samples. The relative populations of the Clostridium coccoides-Eubacterium rectale group, and the genus Streptococcus increased, and that of the genus Fibrobacter decreased in response to increasing temperature both in the first (nine months old, 80% relative humidity) and second (15 months old, 60% relative humidity) experiments. In addition, the population of a defined URB group was higher at 33 degrees C than at 20 degrees C in the second trial, whereas one of the other URB groups showed a decreasing trend with the temperature rise. These results indicate that the exposure to heat affects the population levels of specific bacterial groups in the ruminal microbial community.

Effect of different feeding management on the respiratory methane emission and feces-derived methane yield of goat.

OBJECTIVE: This study aimed to evaluate the respiratory methane emission and ultimate methane yield (B 0) of goat feces that fed roughage consisted of Pennisetum purpureum and Gliricidia) and fed roughage and concentrate with different protein source in the ration (fish meal and soybean meal). MATERIALS AND METHODS: Fifteen Kacang bucks were allocated to the control group (T0): goats were fed roughage only, T1: goats were fed roughage and concentrate with fish meal as protein sources, and T2: goats were fed roughage and concentrate and the protein source in the ration was soybean meal. RESULTS: The protein content of feces from T0 was significantly lower (p < 0.05) than that from the other treatments. The same phenomenon was also found in the respiratory methane emission in terms of l/head/d, l/kg digestible dry matter, and l/kg body weight. However, there was no significant effect (p > 0.05) of different ration composition on the ultimate methane yield (B0 ) of goat feces. This study found that B0 of goat feces from treatment T0, T1, and T2 was 17.40%, 25.78%, and 61.29%, respectively, higher than that from the international default value for developing countries. CONCLUSION: Feeding grass and legume can reduce methane respiration emission in goat. B0 of feces in the present study was higher than that in the international default value; therefore, the potential emission of goat manure in tropical developing countries could be higher than that in the present estimation.

Effects of rumen-protected methionine on milk production in early lactation dairy cattle fed with a diet containing 14.5% crude protein.

We evaluated the influence on milk production of feeding early lactation cows a diet that included 14.5% crude protein (CP) and that did not meet methionine (Met) requirements or that met them by supplying rumen-protected Met (RPMet). Thirty-nine multiparous Holstein cows were allocated into two groups. For 15 weeks after calving, each group was fed one of the two total mixed rations, Control (n = 20) or Treatment (n = 19). The Treatment group received added RPMet at 0.034% (8 g/day) of the Control diet on dry matter basis. The adequacies of Met for the Control and Treatment groups were 96% and 106%, respectively, and for other amino acids, >110%. The CP level (14.5%) was 1 percentage point lower than that recommended by the Japanese Feeding Standard (2006). No between-group differences were found in milk yield (40 kg/day), milk composition, plasma profile, rumen fermentation, nitrogen balance, or cow health. Met intake and the amount of rumen-undegradable feed Met were higher in the Treatment group (p < 0.05). Microbial Met and total metabolizable Met did not differ between groups. Supplying RPMet in a 14.5% CP diet during early lactation did not dramatically affect milk production, because the amount of total metabolizable Met was unchanged.

Properties of cellulose-binding modules in endoglucanase F from Fibrobacter succinogenes S85 by means of surface plasmon resonance.

Properties of the recombinant proteins derived from Fibrobacter succinogenes endoglucanase F (EGF), AD2 and AD4, were characterized using surface plasmon resonance. Because AD2, which contains two reiterated regions, showed stronger affinity to immobilized carboxymethylcellulose (CMC) than did AD4, which contains only the first reiterated region, it has been assumed that the reiterated regions of EGF are cellulose-binding modules. While calcium enhanced the binding of AD2 to the immobilized CMC, it did not enhance the binding of AD4. Moreover, the results obtained from experiments using cellooligosaccharides showed that the binding sites of AD4 and AD2 span approximately four and nine glucosyl units, respectively.

Possible quorum sensing in the rumen microbial community: detection of quorum-sensing signal molecules from rumen bacteria.

The bioluminescence assay using Vibrio harveyi BB170 was used to examine quorum-sensing autoinducer 2 (AI-2) activity from cell-free culture fluids of rumen bacteria. The assay showed that the culture fluids of four species of rumen bacteria, Butyrivibrio fibrisolvens, Eubacterium ruminantium, Ruminococcus flavefaciens, and Succinimonas amylolytica, contained AI-2-like molecules. Furthermore, homologues for luxS genes were detected in rumen fluids collected from three cows and in bacterial cells of P. ruminicola subsp. ruminicola and R. flavefaciens. These findings suggest that the quorum-sensing system mediated by AI-2 is present in the rumen.

Effects of growth and dietary crude protein level until first insemination on milk production during first lactation in Holstein heifers.

To decrease the age at first calving in Holsteins, the effects of average daily body weight gain (ADG) and crude protein (CP) level until first insemination on growth performance and milk production were examined. The MM group had a target ADG of 0.75 kg and received a diet with a CP level of 14%. The HM and HH groups had a target ADG of 1 kg; both these groups received a diet with CP levels 14% and 16%, respectively. The ADG in the HM and HH groups was 1.1 kg, whereas in the MM group it was 0.97 kg (P < 0.01). The HM and HH groups showed no differences in withers height at body weight 350 kg. The ages at first calving in MM, HM and HH groups were 23.1, 21.0 and 21.8 months, respectively. The HM and HH groups had lower milk yield at day 305 than the MM group (P < 0.01). These results suggest that growth performance until first insemination should be maintained at an ADG of 0.97 kg or less with a CP level of approximately 14%, to shorten time until first insemination and prevent the decrease of milk yield.

Influence of high temperature and humidity on rumen bacterial diversity in Holstein heifers.

The effect of heat and humidity stresses on the rumen bacterial molecular diversity of heifers was studied. No statistically significant changes in the rumen microbiota composition were found in the first experiment (average body mass 250kg) while in the second and third experiments (additional variables included the relative humidity and body weight), the microbiota composition was significantly different at elevated environmental temperatures and humidity. These shifts were accompanied by the decrease in concentration of short-chain fatty acids in the rumen.

PCR detection of DNAs of animal origin in feed by primers based on sequences of short and long interspersed repetitive elements.

PCR primers for the detection of materials derived from ruminants, pigs, and chickens were newly designed on the basis of sequences of the Art2 short interspersed repetitive element (SINE), PRE-1 SINE, and CR1 long interspersed repetitive element (LINE), respectively. These primers amplified the SINE or LINE from total DNA extracted from the target animals and from test feed containing commercial meat and bone meal (MBM). With the primers, detection of Art2, PRE-1, or CR1 in test feed at concentrations of 0.01% MBM or less was possible. This method was suitable for the detection of microcontamination of feed by animal materials.