Effects of heat treatment on rumen degradability and protein intestinal digestibility of black soldier fly (Hermetia illucens L.) in goat.

The black soldier fly larvae (BSF) are used as a substitute for soybean meal due to their high crude protein content. This experiment aims to assess the impact of heat treatment on the rumen degradability of BSF and protein digestion in the small intestine using the in situ nylon bag method and the three-step in vitro method. This study comprises a total of 8 groups (n = 6). The negative control group includes only full-fat soybeans (FFS) and BSF (FF group and BS group). The positive control groups consist of a 95% BSF or 95% FFS mixed with 5% cassava (FFC and BSC groups). The treatment groups involve adding 75% water to the positive control mixture, followed by vigorous kneading to achieve uniform mixing. The resulting mixture was then pressed to a thickness of approximately 5 cm, placed in an oven, and dried for 120 min at temperatures of 120 °C and 140 °C (12FFC, 14FFC, 12BSC, and 14BSC groups). Nylon bags will be incubated in the rumen for 0, 2, 4, 8, 12, 24, and 48 h, and the small intestine protein digestion rate will be analyzed at 16 h. Compared to the BS group, heat-treated BSF showed increased (P < 0.05) rumen DM degradability and effective degradability. The 14BSC group increased (P < 0.05) rumen CP degradability and degradation kinetic parameters, while the 12BSC group decreased (P < 0.05) these parameters. The CP degradability of BSF was significantly higher (P < 0.05) than that of full-fat soybeans. The Idg and IDCP of heat-treated full-fat soybeans were significantly higher (P < 0.05) than those of other treatment groups. At the same time, heat treatment was beneficial for increasing (P < 0.05) the Idg and IDCP of BSF, and the 14BSC treatment effect was significantly better (P < 0.05) than that of the 12BSC group. Therefore, based on the results of this experiment, it is recommended to supplement BSF with cassava and subject them to heat treatment at 140 °C.

In Situ Degradation Kinetics of 25 Feedstuffs and the Selection of Time Points in Mathematical Statistics.

Rumen degradation kinetics of 25 feedstuffs (six protein feeds, nine energy feeds and ten roughages) were first determined using the nylon bag technique in situ and the differences of degradation characteristics fitted with five or seven time points measuring data were evaluated with the goodness of fit (R2) of degradation curves. Protein and energy feeds were incubated for 2, 4, 8, 16, 24, 36, 48 h, roughages were incubated for 4, 8, 16, 24, 36, 48, 72 h, where three and six data sets of five time points were screened out, respectively. Only the degradation parameters a (rapidly degraded proportion), b (slowly degraded proportion) and c (degradation rate of slowly degraded proportion) of several feeds at five time points were significantly different from those at seven time points (p < 0.05), and the others were not significant (p > 0.05). The R2 of the degradation curves obtained at five time points was closer to 1, indicating that the fitting obtained at five time points was more accurate in predicting the real-time rumen degradation rate of feed. These results indicate that it is feasible to determine the rumen degradation characteristics of feedstuffs by only setting five measuring time points.

In situ degradation of dairy cattle feedstuffs using reusable local nylon fabric bags.

Background and Aim: Disposable imported nylon bags used in an in situ digestibility measurement restrict the effort of scientists to obtain more accurate information about ruminant feed quality due to their low affordability and environmentally unfriendly characteristics. This study aimed to find reusable local nylon fabrics to substitute imports. Materials and Methods: Five local fabrics (B1 = Abutai, B2 = Taffeta, B3 = Organza, B4 = N57, and B5 = M100) were used to make nylon bags and compared with the imported bag (B6 = Ankom technology). The research consisted of three steps: (1) Observing the similarity of the local nylon bag's hole number to the imported bag. (2) Testing feed in situ degradation (F1 = Napier grass, F2 = Cornmeal, and F3 = Dairy cattle total mixed ration) using bags B1-B6. (3) The reusability of the bag was tested using different washing methods (under running water [R1], rinse [R2], and ultrasonic water bath [R3]). Results: It was shown that the hole numbers of B1 (1223 hole numbers) and B2 (1245 hole numbers) were not significantly different from B6 (1248 hole numbers). It was shown with dry matter degradability measurement using the in situ method that there was no significant difference in feed solubility (a), potential degradability (b), and the effective degradation between local fabrics (B1-B5) and B6. According to the degradation rate (c), there were interactions between the feeds and fabrics. For F1, all local fabrics were similar to B6, while for F2, only B1 was different from B6. For F3, only B5 was different from B6. It was also shown by the organic matter degradability measurements that there was a similar trend. The exception was the solubility (a) component in F3, in which it was shown that B1 was also different from B6. It was shown in the reusable test that there was no difference in the weight of the bag before and after all washing methods. In contrast, the hole number increased due to the shrinking of the bag after drying in a 60°C oven. Conclusion: According to this in situ study, local nylon bag B2 can substitute imported bags. A lower drying temperature is suggested to prevent shrinking and make the bag reusable.

In Vitro Neutral Detergent Cellulase Method and Chemical Composition to Predict In Vivo Fermentable Organic Matter of Roughages.

In Vivo fermentable organic matter (FOM) reflects the energy production and the potential of rumen's microbial protein synthesis. However, the in vivo method with fistulated animals for FOM measurement compromises animal welfare and is laborious as well as expensive. Although the alternative in situ nylon bag technique has been widely used, it is also costly and requires rumen liquor. Therefore, the present study was performed to compare the in situ nylon bag technique with the in vitro neutral detergent cellulase (NDC) method or chemical composition to estimate in vivo FOM of roughages. For this purpose, we selected 12 roughages, including six each from forages and crop residues. Our results have shown the strong correlation equations between FOMin situ and FOMNDC of forages (n = 6; R2 = 0.79), crop residues (n = 6; R2 = 0.80), and roughages (n = 12; R2 = 0.84), respectively. Moreover, there were also strong correlations between the chemical composition of roughages and FOMin situ (n = 12; R2 = 0.84-0.93) or FOMNDC (n = 12; R2 = 0.79-0.89). In conclusion, the in vitro NDC method and chemical composition were alternatives to in situ nylon bag technique for predicting in vivo FOM of roughages in the current experiment.

Effect of Dietary Forage: Concentrate Ratio on Pre-Caecal and Total Digestive Tract Digestibility of Diverse Feedstuffs in Donkeys as Measured by the Mobile Nylon Bag Technique.

The domestic donkey is a unique equid species with specific nutritional requirements, however, limited laboratory evidences are available to address the digestibility contribution of the prececum in relation to the total digestive tract. In the present study, six caecum-fistulated adult female Xinjiang donkeys served as the experimental animals in a 3 × 3 Latin square design, and mobile nylon bag technique was applied to determine the effect of dietary F:C ratio on pre-caececum and total digestive tract digestibility of rice straw, alfalfa hay, corn meal, and soybean meal. The dietary treatments included: (1) HF, a high-fiber ration (F:C = 80:20), (2) MF, a medium-fiber ration (F:C = 55:45), and (3), LF, a low-fiber ration (F:C = 35:65). The experiment consisted of three consecutive Latin square periods, and each period lasted 25 days. In each period, the animals were administrated naso-gastrically nylon bags (38 µm pore size) containing aforementioned feeds. After 1.5 h intubation, the bags were checked once an hour and collected at the ileo-caecal junction (small intestine bag, D1) and in the feces (fecal bag, D2). Regardless whatever feeds were introduced, the percentage of bag collected (BC) was quadratically (HF) or linearly (MF and LF) increased against different fixed bag collection time. The highest BC occurred in MF (73.8%), but no significant difference was observed between HF (62.3%) and LF (50.8%). The lowest mean bag retention time was observed in HF (2.7 h), and no significant difference occurred between MF (4.6 h) and LF (5.0 h) diets. For each feed, D1 and D2 digestibility for DM, CP, NDF, and ADF did not differ among three dietary treatments (p > 0.05). Regardless of whatever diets were fed to the donkeys, D2 digestibility for DM and CP among the feeds ranked as: soybean meal > corn meal > alfalfa hay > rice straw (p < 0.01). D1 digestibility for DM among the feeds ranked as: corn meal > soybean meal > alfalfa hay > rice straw (p < 0.01). D1 digestibility for CP among the feeds ranked as: soybean meal > corn meal > alfalfa hay > rice straw (p < 0.01). In summary, dietary forage: concentrate ratio did not affect pre-caecal or total tract nutrient digestibility. The fiber level in feeds was the main limiting factor to affect the digestibility contribution of the pre-caecum in relation to the total digestive tract.

Influence of barley grain treated with alkaline compounds or organic extracts on ex vivo site and extent of digestion of starch.

OBJECTIVE: Two ex vivo experiments were conducted to verify the effect of barley grain (Nusrat cultivar) treated with alkaline compounds (AC) including alum, ammonium, and sodium hydroxide or cation-exchanged organic extracts (OE) prepared from alfalfa hay, sugar beet pulp and Ulva Fasciata, on extent and digestion of starch. METHODS: In the first study, the in vitro first order disappearance kinetic parameters of dry matter (DM), crude protein (CP) and starch were estimated using a non-linear model (D(t) = D(i) · e(-kd · time) + I, where: D(t) = potentially digestible residues at any time, D(i) = potentially digestible fraction at any time, kd = fractional rate constant of digestion (/h), I = indigestible fraction at any time). In the second experiment, the ruminal and post-ruminal disappearance of DM, CP, and starch were determined using in situ mobile nylon bag. RESULTS: Barley grains treated with alum and alfalfa extract had a higher constant rate of starch digestion (0.11 and 0.09/h) than others. Barley grain treated with OE had a higher constant rate of CP digestion and that of treated with AC had a higher constant rate of starch digestion (0.08 and 0.11/h) compared with those of the other treatments. The indigestible fraction of starch treated with alum and sugar beet pulp extract was higher than that of the control group (0.24 and 0.25 vs 0.21). Barley grain treated with AC and OE had significant CP disappearance in the rumen, post-rumen and total tract, and also starch disappearance for post-rumen and total tract compared with the untreated (p<0.001). CONCLUSION: This study demonstrated that AC and OE might have positive effects on the starch degradation of the barley grain. In addition, treating barley grain with alum and sugar beet pulp extract could change the site and extend digestion of protein and starch.

The development of an intraruminal nylon bag technique using non-fistulated animals to assess the rumen degradability of dietary plant materials.

Although the conventional in situ ruminal degradability method is a relevant tool to describe the nutritional value of ruminant feeds, its need for rumen-fistulated animals may impose a restriction on its use when considering animal welfare issues and cost. The aim of the present work was to develop a ruminal degradability technique which avoids using surgically prepared animals. The concept was to orally dose a series of porous bags containing the test feeds at different times before slaughter, when the bags would be removed from the rumen for degradation measurement. Bags, smaller than those used in the conventional nylon bag technique, were made from woven nylon fabric, following two shape designs (rectangular flat shape, tetrahedral shape) and were fitted with one of three types of device for preventing their regurgitation. These bags were used in two experiments with individually housed non-pregnant, non-lactating sheep, as host animals for the in situ ruminal incubation of forage substrates. The bags were closed at the top edge by machine stitching and wrapped in tissue paper before oral dosing. Standard times for ruminal incubation of substrates in all of the tests were 4, 8, 16, 24, 48, 72 and 96 h before slaughter. The purpose of the first experiment was to compare the effectiveness of the three anti-regurgitation device designs, constructed from nylon cable ties ('Z-shaped', ARD1; 'double Z-shaped', ARD2; 'umbrella-shaped', ARD3), and to observe whether viable degradation curves could be generated using grass hay as the substrate. In the second experiment, three other substrates (perennial ryegrass, red clover and barley straw) were compared using flat and tetrahedral bags fitted with type ARD1 anti-regurgitation devices. Non-linear mixed-effect regression models were used to fit asymptotic exponential curves of the percentage dry matter loss of the four substrates against time of incubation in the reticulorumen, and the effect of type of anti-regurgitation device and the shape of nylon bag. All three devices were highly successful at preventing regurgitation with 93% to 100% of dosed bags being recovered in the reticulorumen at slaughter. Ruminal degradation data obtained for tested forages were in accordance with those expected from the conventional degradability technique using fistulated animals, with no significant differences in the asymptotic values of degradation curves between bag shape or anti-regurgitation device. The results of this research demonstrate the potential for using a small bag technique with intact sheep to characterise the in situ ruminal degradability of roughages.

Rumen fermentation and digestibility of spent mushroom ( Pleurotus ostreatus ) substrate inoculated with Lactobacillus brevis for Hanwoo steers / Fermentación ruminal y digestibilidad de la cama de champiñón (Pleurotus ostreatus) desechada inoculada con Lactobacillus brevis en novillos Hanwoo / Fermentação ruminal e digestibilidade de resíduo de substrato de cogumelo (Pleurotus ostreatus) inoculado com Lactobacillus brevis en novilhos Hanwoo

Abstract Background: Ensiling spent mushroom substrate (SMS) generally increases its nutrient digestibility and quality. Objective: To determine the feed quality and digestibility of SMS from Pleurotus ostreatus (SMSP) inoculated with lactic acid bacteria (LAB: Lactobacillus brevis) in Hanwoo steers. Methods: Ruminal disappearance of SMSP and inoculated SMSP (ISMSP) were evaluated in three rumen-fistulated Hanwoo steers (408 ± 13.0 Kg body weight). Further, three healthy Hanwoo steers (336 ± 69.0 Kg body weight) were randomly allotted to one of three dietary treatments (control: 25% straw, 75% concentrates; treatments: 25% straw, 60% concentrates, and 15% of either SMSP or ISMSP) in a 3×3 Latin square design. Results: The chemical composition of the ISMSP diet did not differ from that of the control or the SMSP diets. In the ISMSP diet, the rate of decrease of pH of ruminal fluid and the increase in storage period was greater than with the SMSP diet. Ruminal disappearance of dry matter, crude protein, neutral detergent fiber, and acid detergent fiber were slightly higher in steers fed ISMSP than those fed SMSP. Furthermore, the degradation rate and effective degradability of crude protein was greater in the ISMSP diet than in the SMSP diet. Effective ruminal fermentation characteristics and total nutrients digestibility were not affected by SMSP nor ISMSP diet. Conclusion: The SMSP and ISMSP diets could replace formulated concentrate without adverse effects and be a cost-effective feed for Hanwoo steers. Furthermore, LAB inoculation improved the SMSP preservation.

Resumen Antecedentes: El ensilado de cama de champiñón desechada (SMS) generalmente aumenta la digestibilidad y la calidad de sus nutrientes. Objetivo: Determinar la calidad del alimento y digestibilidad del SMS a partir de Pleurotus ostreatus (SMSP) inoculado con bacterias ácido-lácticas (LAB: Lactobacillus brevis) en bueyes Hanwoo. Métodos: La desaparición ruminal del SMSP y ISMSP (SMSP inoculado) fue evaluada en tres bueyes Hanwoo fistulados en el rumen (408 ± 13,0 Kg peso corporal). Igualmente, tres bueyes Hanwoo sanos (336 ± 69,0 Kg peso corporal) fueron asignados al azar a uno de los tres tratamientos dietéticos (control: 25% de heno, 75% de concentrados; tratamientos: 25% de heno, 60% de concentrados y 15% de SMSPo ISMSP) en un diseño cuadrado latino 3×3. Resultados: La composición química de la dieta ISMSP no difirió de la del control o de la dieta SMSP. En la dieta ISMSP, la tasa de disminución del pH del fluido ruminal y el incremento del tiempo de almacenamiento fueron mayores que los de la dieta SMSP. La desaparición ruminal de la materia seca, proteína cruda, fibra detergente neutra y la fibra detergente ácida fue ligeramente superior en los bueyes alimentados con el ISMSPque en aquellos alimentados con SMSP. Además, la tasa de degradación y la degradabilidad efectiva de la proteína cruda fueron mayores en la dieta ISMSPque en la dieta SMSP. Las características de la fermentación ruminal efectiva y la digestibilidad total de nutrientes no fueron afectadas por la dieta SMSP ni por la de ISMSP. Conclusión: Las dietas SMSPe ISMSP podrían reemplazar el concentrado formulado sin efectos adversos y ser una alimentación económica para los bueyes Hanwoo. Además, la inoculación con LAB mejoró la conservación del SMSP.

Resumo Antecedentes: Ensilagem de resíduo de substrato de cogumelo (SMS) geralmente aumenta a digestibilidade e a qualidade dos nutrientes. Objetivo: Determinar a qualidade da alimentação e digestibilidade do RSC apartir do Pleurotus ostreatus (SMSP) inoculado com bactérias de ácido láctico (LAB: Lactobacillus brevis) nos novilhos Hanwoo. Métodos: Desaparecimento ruminal do SMSP e ISMSP (SMSP inoculado) foram avaliados em três novilhos Hanwoo fistulados no rúmen (408 ± 13.0 Kg peso corporal). Além disso, três novilhos Hanwoo (336 ± 69.0 Kg peso corporal) foram aleatoriamente distribuídos para um dos três tratamentos dietéticos (controle: 25% palha, 75% concentrado; tratamentos: 25% palha, 60% concentrado, e 15% ambos SMSP e ISMSP) em um quadrado Latino de 3×3. Resultados: A composição química da dieta ISMSP não diferiu do controle ou das dietas SMSP. Na dieta ISMSP, a taxa de diminuição do pH do fluido ruminal e o aumento no período de armazenamento foram melhores do que com a dieta SMSP. O desaparecimento ruminal de matéria seca, proteína bruta, fibra em detergente neutro, e fibra detergente ácido foi ligeiramente superior em novilhos alimentados com ISMSP, do que aqueles alimentados com SMSP. Além disso, a taxa de degradação e degradabilidade da proteína bruta foi maior na dieta ISMSP, do que na dieta SMSP. As características efetivas de fermentação ruminal e a digestibilidade total de nutrientes não foram afetadas pela dieta SMSP, nem pela dieta ISMSP. Conclusão: Dietas com SMSP e ISMSP podem ser utilizados em substituição ao concentrado formulado sem causar efeitos adversos e ser um alimento rentável em novilhos Hanwoo. Além disso, a inoculação com LAB melhorou a qualidade conservante da SMSP.

The effect of pelleting on in situ rumen degradability of compound feed containing brown rice for dairy cows.

This study was conducted to determine the effect of pelleting on in situ dry matter degradability of pelleted compound feed containing brown rice for dairy cows. Mash feed of the same composition was used as a control and the in situ study was conducted using three non-lactating Holstein steers fitted with a rumen cannula. The feeds contained 32.3% brown rice, 19.4% rapeseed meal, 11.4% wheat bran and 10.6% soybean meal (fresh weight basis). Except for moisture content, the chemical composition of the feed was not affected by pelleting. In situ dry matter disappearance of the feed increased from 0 to 2 h and after 72 h of incubation with pellet processing. Integration of the dry matter disappearance values over time revealed that degradability parameter a (soluble fraction) increased with pellet processing, whereas parameter b (potentially degradable fraction) decreased. Parameter c (fractional rate of degradation) and effective degradability (5% passage rate) were not affected by pellet processing. We concluded that pellet processing promotes rumen degradability at early incubation hours when the pelleted feed contains brown rice.

Evaluation of Cross-contamination of Nylon Bags with Heavy-loaded Gasoline Fire Debris and with Automotive Paint Thinner.

Nylon bags are used for packaging fire debris in several countries, particularly in Europe. The possibility of cross-contamination during transport from the fire scene to the laboratory, in normal casework conditions in the U.K., was studied for two brands of nylon bags, using simulated heavy-loaded fire debris. Three experiments were carried out with each brand, using as sample a piece of cotton fabric soaked with gasoline. One experiment was carried out using automotive paint thinner (oxygenated solvent). Each sample was sealed in a nylon bag and stored in contact with eight empty bags. The empty bags were analysed at regular intervals for a period of time up to 8 weeks, using SPME and GC/MS. Cross-contamination was found for components of gasoline (toluene and C2 -alkylbenzenes) in the two brands of nylon bags used, after 4 days and 2 weeks. Cross-contamination using automotive topcoat thinner was detected after 2 days.

Optimal Cultivation Time for Yeast and Lactic Acid Bacteria in Fermented Milk and Effects of Fermented Soybean Meal on Rumen Degradability Using Nylon Bag Technique.

The objectives of this study were to determine an optimal cultivation time for populations of yeast and lactic acid bacteria (LAB) co-cultured in fermented milk and effects of soybean meal fermented milk (SBMFM) supplementation on rumen degradability in beef cattle using nylon bag technique. The study on an optimal cultivation time for yeast and LAB growth in fermented milk was determined at 0, 4, 8, 24, 48, 72, and 96 h post-cultivation. After fermenting for 4 days, an optimal cultivation time of yeast and LAB in fermented milk was selected and used for making the SBMFM product to study nylon bag technique. Two ruminal fistulated beef cattle (410±10 kg) were used to study on the effect of SBMFM supplementation (0%, 3%, and 5% of total concentrate substrate) on rumen degradability using in situ method at incubation times of 0, 2, 4, 6, 12, 24, 48, and 72 h according to a Completely randomized design. The results revealed that the highest yeast and LAB population culture in fermented milk was found at 72 h-post cultivation. From in situ study, the soluble fractions at time zero (a), potential degradability (a+b) and effective degradability of dry matter (EDDM) linearly (p<0.01) increased with the increasing supplemental levels and the highest was in the 5% SBMFM supplemented group. However, there was no effect of SBMFM supplement on insoluble degradability fractions (b) and rate of degradation (c). In conclusion, the optimal fermented time for fermented milk with yeast and LAB was at 72 h-post cultivation and supplementation of SBMFM at 5% of total concentrate substrate could improve rumen degradability of beef cattle. However, further research on effect of SBMFM on rumen ecology and production performance in meat and milk should be conducted using in vivo both digestion and feeding trials.

Application of automatic photography in Schistosoma japonicum miracidi-um hatching experiments / 中国血吸虫病防治杂志

Objective To explore the value of automatic photography in the observation of results of Schistosoma japoni?cum miracidium hatching experiments. Methods Some fresh S. japonicum eggs were added into cow feces,and the samples of feces were divided into a low infested experimental group and a high infested group(40 samples each group). In addition,there was a negative control group with 40 samples of cow feces without S. japonicum eggs. The conventional nylon bag S. japonicum miracidium hatching experiments were performed. The process was observed with the method of flashlight and magnifying glass combined with automatic video(automatic photography method),and,at the same time,with the naked eye observation meth?od. The results were compared. Results In the low infested group,the miracidium positive detection rates were 57.5% and 85.0%by the naked eye observation method and automatic photography method,respectively(χ2=11.723,P 0.05). In the two infested groups,the average positive detection rates were 77.5% and 92.5% by the naked eye observation method and automatic photography method,respectively(χ2 = 6.894,P <0.05). Conclusion The automatic photography can effectively improve the positive detection rate in the S. japonicum miracidi?um hatching experiments.

[Application of automatic photography in Schistosoma japonicum miracidium hatching experiments].

OBJECTIVE: To explore the value of automatic photography in the observation of results of Schistosoma japonicum miracidium hatching experiments. METHODS: Some fresh S. japonicum eggs were added into cow feces, and the samples of feces were divided into a low infested experimental group and a high infested group (40 samples each group). In addition, there was a negative control group with 40 samples of cow feces without S. japonicum eggs. The conventional nylon bag S. japonicum miracidium hatching experiments were performed. The process was observed with the method of flashlight and magnifying glass combined with automatic video (automatic photography method), and, at the same time, with the naked eye observation method. The results were compared. RESULTS: In the low infested group, the miracidium positive detection rates were 57.5% and 85.0% by the naked eye observation method and automatic photography method, respectively (χ2 = 11.723, P < 0.05). In the high infested group, the positive detection rates were 97.5% and 100% by the naked eye observation method and automatic photography method, respectively (χ2 = 1.253, P > 0.05). In the two infested groups, the average positive detection rates were 77.5% and 92.5% by the naked eye observation method and automatic photography method, respectively (χ2 = 6.894, P < 0.05). CONCLUSIONS: The automatic photography can effectively improve the positive detection rate in the S. japonicum miracidium hatching experiments.

Ruminal degradability and intestinal digestibility of individual amino acids in mixed diets with different crude protein levels measured by the modified in vitro three-step and mobile nylon bag technique.

The ruminal degradability and intestinal digestibility of dry matter (DM), crude protein (CP) and amino acids (AA) in three total mixed rations with different CP levels were estimated using the modified in vitro three-step procedure (TSP) and mobile nylon bag (MNB) technique on growing lambs. The ruminal effective degradability of DM and CP did not respond with increasing dietary CP level. However, the intestinal digestibility of DM was significantly increased with increasing dietary CP level estimated by TSP (P < 0.05) or MNB method (P < 0.01). Intestinal digestibility coefficients of CP determined by TSP were lower than those of the MNB method. Histidine was extensively degraded by rumen micro-organisms, while tyrosine was the most anti-degradable AA among the samples. The ruminal AA degradability exhibited no significant differences except for threonine, tryptophan, alanine, aspartic acid and proline for the three diets. Similarly, only a few AAs (i.e. histidine, methionine, tryptophan, aspartic acid and cysteine in TSP; histidine, tryptophan, aspartic acid and serine in MNB) had significant differences in their intestinal digestibility; in addition, values of MNB were lower than that of the TSP method, indicating that intestinal digestibility of DM seems to be overestimated in TSP, while that of CP might be overestimated in the MNB method.

Comparison of three 15N methods to correct for microbial contamination when assessing in situ protein degradability of fresh forages.

The use of stable (15)N as a marker to determine microbial contamination in nylon bag incubation residues to estimate protein degradability was investigated. Three methods using (15)N were compared: (15)N-labeled forage (dilution method, LF), (15)N enrichment of rumen solids-associated bacteria (SAB), and (15)N enrichment of rumen liquid-associated bacteria (LAB). Herbage from forages differing in protein and fiber contents (early-cut Italian ryegrass, late-cut Italian ryegrass, and red clover) were freeze-dried and ground and then incubated in situ in the rumen of 3 steers for 3, 6, 12, 24, and 48 h using the nylon bag technique. The (15)N-labeled forages were obtained by fertilizing the plots where herbage was grown with (15)NH4 (15)NO3. Unlabeled forages (obtained from plots fertilized with NH4NO3) were incubated at the same time that ((15)NH4)2SO4 was continuously infused into the rumen of the steers, and then pellets of labeled SAB and LAB were isolated by differential centrifugation of samples of ruminal contents. The proportion of bacterial N in the incubation residues increased from 0.09 and 0.45 g bacterial N/g total N at 3 h of incubation to 0.37 and 0.85 g bacterial N/g total N at 48 h of incubation for early-cut and late-cut ryegrass, respectively. There were differences (P < 0.001) between uncorrected N degradability values and those corrected for microbial contamination with all of the methods. Apparent N degradability of the low-N, high-fiber forage (late-cut ryegrass) was 0.51, whereas the corrected values were 0.85, 0.84, and 0.77 for the LF, SAB, and LAB methods, respectively. With early-cut ryegrass and red clover, the differences between uncorrected and corrected values ranged between 6% and 13%, with small differences among the labeling methods. Generally, methods using labeled forage or labeled SAB and LAB provided similar corrected degradability values. The accuracy in estimating the extent of degradation of protein in the rumen from in situ disappearance curves is improved when values are corrected for microbial contamination of the bag residue.

Determining nutrients degradation kinetics of chickpea (Cicer arietinum) straw using nylon bag technique in sheep.

Straw a by-product from grain legume crops is produced in large quantities in Iran. Straw is constant component of ruminant diets on small holder farms; however, there is little information about its nutritive value. Accordingly experiment was conducted to determine the chemical composition and ruminal organic matter (OM) and crude protein (CP) degradability of chickpea straw using nylon bags (in situ) technique. Replicated samples were incubated at 0, 2, 4, 8, 12, 24, 48 and 72 hours in three rumen canulated Ghezel rams with 50±3 kg body weight. Dry matter (DM), CP, ether extract (EE), OM, crude fiber (CF) and nitrogen free extract (NFE) content of chickpea straws were 92.2, 6.1, 5.5, 92.0, 34.3 and 46.2%, respectively. The soluble fraction (a) of the OM and CP of chickpea straw was 17.5 and 40.8% and potential degradability (a+b) of OM and CP was 56.7 and 72.0%, respectively. Effective degradability at different passage rates (2, 5 and 8% per hours) for OM was 51.0 44.9 and 40.7% and for CP were 68.4, 64.3 and 61.3%, respectively. In conclusion, based on chemical composition and degradation characteristics, chickpea straw could have moderate nutritive value for ruminants.