• Asian-Australasian Journal of Animal Sciences
• /
• 제15권10호
• /
• pp.1439-1444
• /
• 2002

An objective of this study was to determine the effects of increasing contents of rumen undegradable protein (RUP) from formalin treated soy bean (FSBM) on rumen functions. Four rumen canulated non-lactating cows were randomly allocated to total mixed rations (TMR) containing different proportions of soy bean meal (SBM) and FSBM. Of rumen fermentation characteristics, concentrations of ruminal fluid ammonia and molar proportions of isoacids decreased with increasing contents of RUP in diets (p<0.01). The animals on TMR containing only SBM gained less weight and had smaller rumen volume than those on TMR containing RUP from FSBM (p<0.05). Organic matter and neutral detergent fiber digestibility in sacco were not different (p>0.05). The density of protozoa particularly small Entodinium sp. in ruminal fluid was higher in animal fed TMR containing SBM:FSBM (34:66) and FSBM than those fed TMR containing SBM:FSBM (66:34) and SBM (p<0.01). Total viable count, and net microbial protein synthesis as indicated by purine derivatives in urine increased with increasing contents of RUP from FSBM (p<0.01). It can be concluded that a reduction in net microbial protein synthesis in the rumen with increasing contents of RUP in the diet can be due to the reduction of preformed protein available for microbial growth as well as an increased turnover rate of microbial cells by predatory activity of protozoa.

• Asian-Australasian Journal of Animal Sciences
• /
• 제22권1호
• /
• pp.131-138
• /
• 2009

Among rumen microbes, bacteria play important roles in the biological degradation of plant fiber due to their large biomass and high activity. To maximize the utilization of fiber components such as cellulose and hemicellulose by ruminant animals, the ecology and functions of rumen bacteria should be understood in detail. Recent genome sequencing analyses of representative fibrolytic bacterial species revealed that the number and variety of enzymes for plant fiber digestion clearly differ between Fibrobacter succinogenes and Ruminococcus flavefaciens. Therefore, the mechanism of plant fiber digestion is also thought to differ between these two species. Ecology of individual fibrolytic bacterial species has been investigated using pure cultures and electron microscopy. Recent advances in molecular biology techniques complement the disadvantages of conventional techniques and allow accurate evaluation of the ecology of specific bacteria in mixed culture, even in situ and in vivo. Molecular monitoring of fibrolytic bacterial species in the rumen indicated the predominance of F. succinogenes. Nutritive interactions between fibrolytic and non-fibrolytic bacteria are important in maintaining and promoting fibrolytic activity, mainly in terms of crossfeeding of metabolites. Recent 16S rDNA-based analyses suggest that presently recognized fibrolytic species such as F. succinogenes and two Ruminococcus species with fibrolytic activity may represent only a small proportion of the total fibrolytic population and that uncultured bacteria may be responsible for fiber digestion in the rumen. Therefore, characterization of these unidentified bacteria is important to fully understand the physiology and ecology of fiber digestion. To achieve this, a combination of conventional and modern techniques could be useful.

• Asian-Australasian Journal of Animal Sciences
• /
• 제13권1호
• /
• pp.96-114
• /
• 2000

Genetically selected beef cattle are fed high-energy diets in intensive production systems developed in industrial countries. This type of feeding can induce rumen dysfunctions that have to be corrected by farmers to optimise cost-effectiveness. The risk of rumen acidosis can be reduced by using slowly degradable starch, which partly escapes rumen fermentation and goes on to be digested in the small intestine. Additives are proposed to stabilise the rumen pH and restrict lactate accumulation, thus favouring the growth of cellulolytic bacteria and stimulating the digestion of the dietary plant cell wall fraction. This enhances the energy value of feeds when animals are fed maize silage for example. Supplementation of lipids to increase energy intake is known to influence the population of rumen protozoa and some associated rumen functions such as cellulolysis and proteolysis. The end products of rumen fermentation are also changed. Lipolysis and hydrogenation by rumen microbes alter the form of fatty acids supplied to animals. This effect is discussed in relation with the quality of lipids in beef and the implications for human health. Conditions for optimising the amount of amino acids from microbial proteins and dietary by-pass proteins flowing to the duodenum of ruminants, and their impact on beef production, are also examined.

• Animal Bioscience
• /
• 제37권2_spc호
• /
• pp.360-369
• /
• 2024

Ruminal methane production functions as the main sink for metabolic hydrogen generated through rumen fermentation and is recognized as a considerable source of greenhouse gas emissions. Methane production is a complex trait affected by dry matter intake, feed composition, rumen microbiota and their fermentation, lactation stage, host genetics, and environmental factors. Various mitigation approaches have been proposed. Because individual ruminants exhibit different methane conversion efficiencies, the microbial characteristics of low-methane-emitting animals can be essential for successful rumen manipulation and environment-friendly methane mitigation. Several bacterial species, including Sharpea, uncharacterized Succinivibrionaceae, and certain Prevotella phylotypes have been listed as key players in low-methane-emitting sheep and cows. The functional characteristics of the unclassified bacteria remain unclear, as they are yet to be cultured. Here, we review ruminal methane production and mitigation strategies, focusing on rumen fermentation and the functional role of rumen microbiota, and describe the phylogenetic and physiological characteristics of a novel Prevotella species recently isolated from low methane-emitting and high propionate-producing cows. This review may help to provide a better understanding of the ruminal digestion process and rumen function to identify holistic and environmentally friendly methane mitigation approaches for sustainable ruminant production.

• Asian-Australasian Journal of Animal Sciences
• /
• 제12권6호
• /
• pp.988-1001
• /
• 1999

The rumen ecosystem is increasingly being recognized as a promising source of superior polysaccharide-degrading enzymes. They contain a wide array of novel enzymes at the levels of specific activities of 1,184, 1,069, 119, 390, 327 and $946{\mu}mol$ Reducing sugar release/min/mg protein for endoglucanase, xylanase, polygalactouronase, amylase, glucanase and arabinase, respectively. These enzymes are mainly located in the surface of rumen microbes. However, glycoside-degrading enzymes (e.g. glucosidase, fucosidase, xylosidase and arabinofuranosidase, etc.) are mainly located in the rumen fluid, when detected enzyme activities according to the ruminal compartments (e.g. enzymes in whole rumen contents, feed-associated enzymes, microbial cell-associated enzymes, and enzymes in the rumen fluid). Ruminal fungi are the primary contributors to high production of novel enzymes; the bacteria and protozoa also have important functions, but less central roles. The enzyme activities of bacteria, protozoa and fungi were detected 32.26, 19.21 and 47.60 mol glucose release/min/mL mediem for cellulose; 42.56, 14.96 and 64.93 mmol xylose release/min/mL medium after 48h incubation, respectively. The polysachharide-degrading enzyme activity of ruminal anaerobic fungi (e.g. Neocallimastix patriciarum and Piromyces communis, etc.) was much higher approximately 3~6 times than that of aerobic fungi (e.g. Tricoderma reesei, T. viridae and Aspergillus oryzae, etc.) used widely in industrial process. Therefore, the rumen ecosystem could be a growing source of novel enzymes having a tremendous potential for industrial applications.

• Journal of Veterinary Science
• /
• 제24권2호
• /
• pp.27.1-27.15
• /
• 2023

Background: The relationships between the postpartum subacute ruminal acidosis (SARA) occurrence and predicted bacterial functions during the periparturient period are still not clear in Holstein cows. Objectives: The present study was performed to investigate the alterations of rumen fermentation, bacterial community structure, and predicted bacterial functional pathways in Holstein cows. Methods: Holstein cows were divided into the SARA (n = 6) or non-SARA (n = 4) groups, depending on whether they developed SARA during the first 2 weeks after parturition. Reticulo-ruminal pH was measured continuously during the study period. Reticulo-ruminal fluid samples were collected 3 weeks prepartum, and 2 and 6 weeks postpartum, and blood samples were collected 3 weeks before, 0, 2, 4 and 6 weeks postpartum. Results: The postpartum decline in 7-day mean reticulo-ruminal pH was more severe and longer-lasting in the SARA group compared with the non-SARA group. Changes in predicted functional pathways were identified in the SARA group. A significant upregulation of pathway "PWY-6383" associated with Mycobacteriaceae species was identified at 3 weeks after parturition in the SARA group. Significantly identified pathways involved in denitrification (DENITRIFICATION-PWY and PWY-7084), detoxification of reactive oxygen and nitrogen species (PWY1G-0), and starch degradation (PWY-622) in the SARA group were downregulated. Conclusions: The postpartum SARA occurrence is likely related to the predicted functions of rumen bacterial community rather than the alterations of rumen fermentation or fluid bacterial community structure. Therefore, our result suggests the underlying mechanisms, namely functional adaptation of bacterial community, causing postpartum SARA in Holstein cows during the periparturient period.

• Asian-Australasian Journal of Animal Sciences
• /
• 제2권3호
• /
• pp.493-496
• /
• 1989

• Asian-Australasian Journal of Animal Sciences
• /
• 제7권1호
• /
• pp.91-96
• /
• 1994

This study was conducted to determine the effect of inorganic selenium (Se) sources on rumen bacterial yield, ruminal volatile fatty acid (VFA) production and total tract digestion of timothy hay (Phlewm pratense L.) in Japanese Corriedale wethers. A $3{\times}3$ Latin square design was used with three wethers, three periods and three treatments. In each period, there was 7 d dietary adjustment followed by 5 d total collection of urine and feces. Ruminal fluid samples were obtained at 0, 1, 3, 5 and 7 h postprandially on the final day of the collection period. The three dietary treatments were: (1) without Se supplementation (control); (2) with Se supplementation as sodium selenate; and (3) sodium selenite at a rate 0.2 mg Se/kg dietary DM. The basal diet was timothy hay fed at 2% of body weight/d. Results indicated that there was slight decrease in rumen bacterial yield of animal supplement with inorganic Se, however, differences over the control were insignificant. It was found that Se content of ruminal fluid was negatively correlated (p < 0.05) to rumen bacterial yield. The various VFA contents and acetate and propionate ratio of the different ruminal fluid samples were insignificant across treatment means and the same manner was observed to the different digestibilities (DM, OM, CP, NDF, ADF and NDS). This study concludes that Se supplementation at 0.2 mg Se/kg dietary DM either from sodium selenate or sodium selenite could not significantly influence rumen bacterial functions.

• Asian-Australasian Journal of Animal Sciences
• /
• 제15권6호
• /
• pp.806-811
• /
• 2002

A 90 d study was designed to investigate the effects of rumen undegradable protein (RUP) and a mixture of Cu, Zn and Mn proteinate (CZMP) on milk yield and composition and ovarian functions during rainy months. Twenty four Holstein${\times}$ indigenous cows in their 2nd and 3rd lactation were randomly allocated to total mixed rations (TMR) containing soy bean meal (SBM) as a source of rumen degradable protein (RDP), SBM plus CZMP, and formalin treated SBM (FSBM) as a source of RUP. Maximum and minimum temperature humidity index during the experimental period were 83.6-84.7 and 75.4-76.1. There were no differences (p>0.05) in intakes of dry matter, crude protein and net energy and in contents of butterfat, lactose and minerals. Cows on TMR containing FSBM not only lost less weight (-278, -467 and -433 g/d) with more intake of RUP (0.92, 0.58 and 0.59 kg/d) but also produced more milk (19.27, 18.23 and 18.13 kg/d) and 4% fat corrected milk (18.57, 17.57 and 17.51 kg/d) with more protein (3.06, 2.81 and 2.80%), solids-not-fat (8.69, 8.38 and 8.38%) and less milk urea N (9.3, 15.4 and 15.0 mg/dl) compared with those on TMR containing SBM and SBM+CZMP, respectively (p<0.01). However, cows on TMR containing SBM and SBM+CZMP did not differ in these respects (p>0.05). Whereas incidence of cystic ovaries at 20 and 90 d pospartum was less (p<0.01) in cows on TMR containing SBM+CZMP (37.3 and 12.5%) than those on TMR containing SBM (62.5 and 25%), it was nil for cows on TMR containing FSBM. Cows in all three group differed (p<0.01) from each other for the recurrence of first observed estrus with those on TMR containing FSBM having least days (22, 36 and 47 d) compared with their counterpart on TMR containing SBM+CZMP and SBM, repectively. The results suggest that RUP is one of the limiting factors affecting milk yield and its composition and ovarian functions during early lactation of dairy cows in the tropics.

• Asian-Australasian Journal of Animal Sciences
• /
• 제2권3호
• /
• pp.411-412
• /
• 1989