Impacts of rumen fluid, refrigerated or reconstituted from a refrigerated pellet, on gas production measured at 24h of fermentation

3noRumen fluid is used as fresh inoculum for gas production fermentations to predict the nutritional value of feeds and rations for ruminants. However, collection of rumen fluid from animal donors is invasive, expensive, time consuming and results in fluids of variable quality. The general aim was to identify a procedure to manipulate rumen inoculum in order to facilitate its storage and transfer between laboratories. This strategy would also limit fluid collections from animals. Two experiments were completed based on gas production from graduated 100 mL glass syringe with five feeds as substrates. In experiment 1, the gas production and some fermentation parameters of fresh rumen fluids were compared with those preserved at 4 °C for 24, 48, 72 and 96 h. Refrigeration did not modify concentration of volatile fatty acids and pH, but ammonia in liquids refrigerated for 48–96 h was higher (P < 0.05) compared to fresh. In contrast, rumen fluid refrigeration for 24, 48 or 72 h did not depress gas production at 24 h, but it was lower at 96 h. In experiment 2, the rumen fluid was centrifugated at 13,000 x g and sedimented material (i.e., pellet) was refrigerated for 48 h at 4 °C. The asymptote of gas production kinetics from rumen fluid regenerated from the pellet was 8 % lower (P < 0.05) than that from fresh. However for 24 h gas production, the correlation between fresh liquid and pellet inoculum, calculated for five ingredients, was high (R2 = 0.94). Results support the use of rumen fluid preserved by refrigeration for up to 72 h, and rumen fluid reconstituted from refrigerated pellet, as an alternative to fresh. This would reduce the need for laboratories to maintain animal donors and/or frequently collect rumen fluid.openopenFabro C.; Sarnataro C.; Spanghero M.Fabro, C.; Sarnataro, C.; Spanghero, M

In vitro ammonia release of urea-treated high moisture barley and maize grain

Rumen nitrogen (N) release from ammoniated wet barley and maize kernels by urea treatment (UT) at harvesting was studied. Untreated samples (CTR) were compared to UT and to samples combined with urea just before the experiment (UA). In Experiment 1, ground CTR, UT and UA samples were fermented in a ruminal in vitro system, and ammonia of fermentation fluid was analysed at 0, 2, 4, 6 and 8 h. The effect of incubation time was observed as ammonia peaked at 4 h of fermentation (10.24 vs 9.01 and 7.20 mg \ub7 dl 121, respectively at 0 and 8 h, P < 0.01). Also, the effect of treatment was stated when UT released less ammonia than UA treatment (9.76 vs 10.52 mg \ub7 dl 121, P < 0.05), while the CTR samples showed the least ammonia N concentrations (P < 0.01). In Experiment 2, the water N solubility of CTR and UT of both cereal samples prepared in three physical forms (whole grain, coarsely ground and milled) was examined. Samples were incubated in flasks with distilled water for 1, 2, 4, 6 and 8 h and N was measured in filtered residues to calculate N solubility. The UT samples, regardless cereal type, solubilised more N in the milled than in the whole form with the coarse form in the middle (43.7 vs 15.3%, 32.4 vs 14.0% and 20.3 vs 9.2% for milled, coarse and whole form, respectively; treatment 7 physical form interaction: P < 0.01). The N added to wet cereal kernels by the urea treatment was released in the rumen fermentation liquid more slowly than that simply added as urea before incubation. Based on solubility data, the treated whole or cracked kernels exhibited a slower N release than milled ones

In vitro aflatoxins recovery after changing buffer or protozoa concentrations in the rumen fermentation fluid

This study simulates in vitro the effects of (i) rumen acidity and (ii) change in rumen protozoa numbers on the recovery of aflatoxins (AFs). Two 24-h fermentation experiments were carried out using the same batch in vitro fermentation systems and substrate (dried corn meal) containing 11.42, 2.42, 7.65 and 1.70 µg/kg of AFB1, AFB2, AFG1 and AFG2 respectively. In Experiment 1, two buffer concentrations (normal salts dosage or lowered to 25%) were tested. Buffer reduction decreased gas production (730 vs. 1101 mL, p < 0.05), volatile fatty acids (VFA) and NH3 concentrations in the fermentation liquid (39.8 vs. 46.3 mmol/L, and 31.7 vs. 46.5 mg/dL respectively, p < 0.01). Recovery of all four AFs types was higher (p < 0.01) in the reduced buffer fermentation fluid, both as a percentage of total AF incubated (73.6% vs. 62.5%, 45.9% vs. 38.1%, 33.6% vs. 17.9% and 18.9% vs. 6.24% for AFB1, AFB2, AFG1 and AFG2 respectively) and as amounts relative to VFA production (163.4 vs. 123.5, 22.1 vs. 15.7, 48.8 vs. 22.5 and 6.16 vs. 1.86 ng/100 mmol of VFA, for AFB1, AFB2, AFG1 and AFG2 respectively). In Experiment 2, Stevia rebaudiana Bertoni extracts (S) or a Camphor essential oil (Cam) were added to fermenters and compared to the control (no additives, C). S and Cam addition resulted in a 25% reduction (p < 0.05) and a 15% increase (p < 0.05) in protozoa counts respectively, when compared to C. Both plant additives slightly reduced (p < 0.05) AFB1 recovery as a percentage of total AFB1 incubated (68.5% and 67.7% vs. 74.9% for S, Cam and C respectively). Recoveries of all other AFs were unaffected by the additives. In conclusion, the rumen in vitro AFB1 recovery (63%–75%) was higher than other AFs (3%–46%) and the acidic fermentation environment increased it. In our conditions, changes in protozoa numbers did not affect AFs recovery

Effect of dietary nitrogen level and source on mRNA expression of urea transporters in the rumen epithelium of fattening bulls

This paper aims to study the effect of the dietary treatments on mRNA expression of urea transporter B (UT-B) and some aquaporins (AQP) in rumen epithelium of Italian Simmental young bulls. Eighty animals allocated to 16 pens were fed from about 500 to 650&nbsp;kg body weight with four experimental diets, which resulted from the combination of two crude protein levels (125 and 110&nbsp;g/kg dry matter, diets M and L, respectively) and two nitrogen sources (soybean meal (SBM) or SBM partly replaced by an isonitrogenous mixture of corn and urea; diets −U and +U, respectively). At slaughtering samples of blood and rumen epithelium were collected from six bulls for each diet. Blood samples were analysed for haematological parameters and quantitative PCR was carried out on the mRNA extracted from the rumen epithelium samples. The bulls fed diets M had lower plasma concentrations of aspartate aminotransferase than those receiving diets L (78.9 vs. 88.3&nbsp;U/l, p&nbsp;=&nbsp;0.04). Plasma urea was higher (p&nbsp;=&nbsp;0.03) for diets M and lower for diets +U (2.0 vs. 2.5 and 1.73 vs. 2.00&nbsp;mmol/l, respectively, in M and L diets, p&nbsp;=&nbsp;0.04). The effect of dietary treatments on rumen UT expression were limited to AQP3, which was down regulated (p&nbsp;=&nbsp;0.01) in diets +U. Finally, a high positive correlation (R2&nbsp;=&nbsp;0.871) between the expressions of AQP7 and AQP10 was found. In conclusion, the AQP3 appears very responsive to dietary treatments and therefore it is a candidate to be further studied in rumen metabolism experiments. The close relationship between mRNA expression of AQP7 and AQP10 indicates a similar function of these two proteins

WAVE MODELLING OF A LIGHTWEIGHT AEROSPACE PANEL USING A FINITE ELEMENT APPROACH

Aerospace structures require high strength and low mass, which has led to an increase in the use of composite materials by its industry. These materials result from the combination of two or more base materials in a way that one or more of the composite’s properties are superior to either of the individual ones. A type of material that presents those desired attributes is the honeycomb sandwich panels and, as the industry is relying more and more on them, their accurate characterization for the given application is of extreme importance. In this paper, the wave and finite element (WFE) approach is applied and thewave parameters of a homogenized honeycomb sandwich panel model for aerospace applications are presented and numerical details discussed. The wave approach differs from the more usual modal analysis (MA) by focusing in properties such as the dispersion relations, wave modes, phase and group velocities, and energy transmission. Although MA with the aid of finite element modelling (FEM) is a widely used technique, as the frequencies of interest increase, the computational cost also increases. Moreover, the size of the elements also limits the maximum frequency that can be accurately characterized. On the other hand, the WFE method requires the model of a single period of a periodic structure, which can be obtained from any commercial FE software, benefiting from the available element libraries,reducing the computational cost when applied to a wider frequency range. The numerically obtained parameters are compared to an analytical model and show agreement with the theory. Keywords: Wave and finite element, Wave propagation, Sandwich pane

Heat stress and feeding behaviour of dairy cows in late lactation

Heat stress is one of the most important problems that dairy cows have to face and the use of cooling systems is becoming more and more important. The first reaction that has the animal to cope with the environmental variations is to modify its behaviour. This study was aimed to investigate the effect of heat stress and a cooling system on the feeding behaviour of Italian Holstein Friesian dairy cows in late lactation. Two experiments were performed. In the first experiment, eight dairy cows were firstly kept 7 d under thermoneutral condition, and then under mild heat stress (temperature humidity index, THI, ranging between 72 and 78) for others 7 d. The second experiment consisted of 8 dairy cows used in a two-period cross-over design where the treatment was the use or not of a sprinkler system for cooling cows under mild heat stress. Cows were equipped with a noseband pressure sensor able to detect rumination and eating time, number of rumination and eating chews, number of rumination boluses and rumination intensity. Heat stress reduced rumination time, number of rumination chews and boluses (p <.05), and tended to reduce the number of eating chews (p <.10). Cooled cows increased rumination and eating time (p <.05), rumination intensity (p <.01), and the number of rumination and eating chews (p <.05). In conclusion, feeding behaviour was deeply influenced even by mild heat stress, which was effectively improved by the use of a sprinkler system.HIGHLIGHTS Mild heat stress reduced rumination time, number of rumination chews and boluses of dairy cows in late lactation Cooling cows with sprinklers was effective in alleviating heat stress in terms of feeding behaviour