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[Preparatory feeding of the dry stage cow in regard to nutritional condition and the status of the rumen mucosa and rumen flora at calving].

Excessive fat deposition prior to calving and a negative energy balance post partum predispose the high producing cow for an intensive postpartal lipolysis and for the health problems resulting thereof. It was postulated that a well proliferated ruminal mucosa at the beginning of lactation could improve the energy supply by stabilizing the pH of the rumen content with energy rich feed and by providing a high absorption capacity for volatile fatty acids. Results of earlier experiments dealing with this problem are reviewed. Furthermore there is described a pilot experiment with 9 dry cows, which was directed to stimulate rumen mucosa growth ante partum by a low energy ration (roughage) during the first half of the dry period and a high energy ration during the last 3 to 4 weeks prior to calving, without inducing a fat cow. The ruminal mucosa reacted to that feeding regimen as expected and desired. The body weight of 3 cows in moderate and 4 cows in medium body condition increased by 7.2% or 3% during 8 to 11 or 7 to 9 weeks respectively. One of two fat cows lost 4.9% of her body weight within 8 to 9 weeks while the condition of the second animal remained unchanged. No problems were observed at calving. A further progress is expected by feeding the dry cows in two groups with different rations according to their body condition at the end of lactation. Results of experiments as well as practical experiences show that no more than 8 to 10 days are necessary to adapt the ruminal flora to a mixed ration (roughage + concentrates).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

[The effect of monensin on the fermentation of feed with different proportions of hay and concentrate in an artificial rumen (rumen simulation technic)].

An experiment was conducted with rumen pouch (RUSITEC--Rumen Simulation Technique). In four fermentation vessels (V), percent proportions of hay and barley were as follows: V1--40:60, V2 - 60:40, V3--80:20 and V4--100:0. Every day 5 mg of monensin dissolved in 1 ml 96% ethanol were added to each fermentation vessel. All diets were isonitrogenous, and after an addition of urea the crude protein (CP) content made 13% in each diet. The experiment lasted 12 days: so called steady state period took the first six days when the fermentation conditions were stabilized. Monensin reduced dry matter digestibility, production of total volatile fatty acids, acetic acid, n-butyric and isovaleric acids and acetate: propionate proportion, and it increased the production of propionic and n-valeric acids. The production of methane and CO2 decreased. The higher proportion of hay in diets decreased dry matter digestibility, digestibility of detergent fibre, total and individual volatile fatty acids, CO2, methane energy yield of volatile fatty acids (E), glucose utilization, production of adenosine triphosphate and production of fermented hexoses. The production, utilization and recovery of metabolic hydrogen also decreased. The effectiveness of microbial matter synthesis (YATP = 11.3) was highest during the fermentation of feed containing 60% hay and 40% barley.

Animal Feed↗

Comparison of substrate affinities among several rumen bacteria: a possible determinant of rumen bacterial competition.

Five rumen bacteria, Selenomonas ruminantium, Bacteroides ruminicola, Megasphaera elsdenii, Streptococcus bovis, and Butyrivibrio fibrisolvens were grown in continuous culture. Estimates of substrate affinities were derived from Lineweaver-Burk plots of dilution rate versus substrate concentration. Each bacterium was grown on at least four of the six substrates: glucose, maltose, sucrose, cellobiose, xylose, and lactate. Wide variations in substrate affinities were seen among the substrates utilized by a species and among species for the same substrate. These wide differences indicate that substrate affinity may be a significant determinant of bacterial competition in the rumen where soluble substrate concentrations are often low. Growth of these bacteria in continuous culture did not always follow typical Michaelis-Menten kinetics. Inflated theoretical maximum growth rates and non-linear Lineweaver-Burk plots were sometimes seen. Maintenance energy expenditures and limitation of growth rate by factors other than substrate concentration (i.e., protein synthesis) are discussed as possible determinants of these deviations.

Journal Article↗

Effects of 3 chemical treatments on in vitro fermentation of rice straw by mixed rumen microbes in the presence or absence of anaerobic rumen fungi.

Rice straw (Rs) was treated by a sodium chlorite/acetic acid mixture (Sct), ammoniation (At) and alkaline hydrogen peroxide (Athp) methods. The objective was to compare their degradation and fermentation products in the presence or suppression of anaerobic fungi. Significant differences (P < 0.01) in degradation of straws were observed during all periods of incubation with Sct having the highest digestibilities during the 48-h and 72-h incubations. The degradation of Sct straw was highest in both of the incubations with whole rumen fluid (WRF) and WRF plus cycloheximide. In sacco digestion followed the order of Sct > At > Rs > Athp. Suppressing fungal activity with cycloheximide resulted in a decrease in dry matter degradation, with concomitant decrease in total volatile fatty-acid concentration. While the suppression of fungal activity with cycloheximide depressed acetate and butyrate production, it favored an increase in propionate production.

Acetates↗

Effect of white-rot basidiomycetes-treated wheat straw on rumen fermentation in artificial rumen.

This study evaluated three white-rot basidiomycetes for their potential to improve the ruminal degradation of wheat straw. Pleurotus ostreatus (PO), Pleurotus ostreatus-mutant (PO-M) and Trametes gibbosa (TG) were incubated on wheat straw for 30 days at 28 degrees C. Neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein and in vitro dry matter digestibility (IVDMD) were determined. The results demonstrated increasing crude protein and ash contents (%) in the fungi-treated straws. The IVDMD values were also increased. Compared to untreated wheat straw (UWS), the NDF and ADF contents were reduced in fungi-treated straw (TWS). Out of the three fractions-hemicellulose, cellulose and lignin-hemicellulose showed the largest proportionate loss and lignin the smallest in all three fungi-treated straws. TWS with Pleurotus ostreatus (TWS-PO), Pleurotus ostreatus-mutant (TWS-PO-M) and Trametes gibbosa (TWS-TG) together with barley (80:20%) were used as the experimental diets in the artificial rumen. UWS with barley (80:20%) served as the control diet. The results revealed significantly higher IVDMD values, NDF, ADF and cellulose digestibilities (%) with the experimental diets. The production of propionic acid decreased, n-butyric, n-valeric and isovaleric acids (mmol/day-1) increased and the volatile fatty acid (VFA) production expressed in mol VFAs.kg-1 digested dry matter decreased in experimental diets. The total microbial production also decreased at fermentation in the experimental diets.

Animals↗

Rumen undegradable protein, rumen-protected choline and mRNA expression for enzymes in gluconeogenesis and ureagenesis in periparturient dairy cows.

The objective of this study was to profile mRNA expression of argininosuccinate synthetase (AS) and ornithine transcarbamylase (OTC), two enzymes that participate in the formation of urea in liver and compare these with changes in mRNA for pyruvate carboxylase (PC) and phosphoenolpyruvate carboxykinase (PEPCK) during the periparturient period in dairy cows. Forty-eight multiparous Holstein cows were fed isoenergetic prepartum diets that contained 10% RDP and either 4.0% RUP or 6.2% RUP and either 0, 6, or 12 g/d of rumen-protected choline (RPC) as CapShure (Balchem Corp., Slate Hill, NY). After calving cows received a common diet and continued RPC as per their prepartum assignments. Liver biopsies were obtained on d -28, -14, 1, 28, and 56 relative to calving, and the abundances of AS, OTC, PC, PEPCK, and 18S mRNA were determined by Northern blot analysis of total RNA. The abundance of OTC mRNA was lowest at calving and was decreased by RPC and 6.2% RUP feeding. Feeding 6.2% RUP did not alter AS, PC, or PEPCK mRNA. The expression of AS mRNA increased and PEPCK mRNA tended to increase from calving to 56 DIM. Pyruvate carboxylase mRNA increased more than twofold at calving. The data indicated adaptation to lactation for gluconeogenic enzymes that is not matched in direction and magnitude by changes in mRNA for urea cycle enzymes. Feeding additional protein, as RUP, failed to induce mRNA for key enzymes in gluconeogenesis or ureagenesis.

Animal Feed↗

Rumen modeling: rumen input-output balance models.

Two models of rumen fermentative relationships expressed as systems of simultaneous linear equations and based on requirements for maintenance of balances of elementary imput and output and metabolic pathways are presented in matrix format consistent with solution by linear programs. Matrix entries defining the two models were verified carefully based upon a survey of the literature, and conceptual bases of the models were validated by comparisons of model outputs with experimental data not used in model construction. The models then were used to evaluate interactions among feed composition, volatile fatty acid yields and patterns, microbial growth yields and efficiencies, and microbial metabolic pathways.

Amino Acids↗