Mobile Nylon Bag Technique Research Articles

Rumen degradation and intestinal digestibility of rumen undegraded dietry nitrogen in grass-lumen mixed diets estimated by the mobile nylon bag technique

No Abstract. Southern African Journal of Education, Science and Technology Vol. 1 (1) 2006: pp. 23-27

Rumen and post-abomasal disappearance in lactating cows of amino acids and other components of barley grain treated with sodium hydroxide, formaldehyde or urea

Four rumen and duodenum cannulated, Holstein lactating cows were used in a change-over design to determine the effects of NaOH, formaldehyde (HCHO) or urea treated barley on disappearance of dry matter (DM), crude protein (CP), amino acids (AA), NDF, ADF and starch of barley in the rumen, post-abomasal (PAT) and total tract by the mobile nylon bag technique. Experimental treatments were coarse milled barley, barley treated with 35 g NaOH/kg, barley treated with 4 g formaldehyde/kg and barley treated with 35 g urea/kg, in which all chemical treated barley was milled coarse before feeding. NaOH treatment reduced concentrations of lysine and cystine in the barley grain. All chemical treatments decreased rumen disappearances of barley CP but only NaOH and formaldehyde treatments also decreased total AA and some of the AA disappearances in the rumen. All chemical treatments increased DM, OM, CP, starch, NDF and ADF disappearance of barley in the PAT, but only NaOH and formaldehyde treatments increased total AA and most individual AA disappearances in the PAT. Chemical treatments increased disappearance of starch, methionine and glycine in the total tract (P<0.05). Rumen disappearance of TAA was lower than for CP but PAT disappearance of TAA was more than for CP and finally total tract disappearance of TAA was more than for CP. Individual AA in barley disappeared at different rates in the rumen and PAT. Consequently, the proportion of digesta CP and AAs of barley, entering the intestine were changed by the chemical treatments. We concluded that, appropriate treatment of barley with NaOH or HCHO were provided substantial protection of CP and individual AA from rumen digestion and increased disappearance of most of barley nutrients in PAT, but, NaOH treatment reduced the AA quality of barley. Consequently, formaldehyde can therefore be considered better than NaOH and urea for treatment of barley grain.

Intestinal digestibility of protein and amino acid of ruminant feeds with the mobile nylon bag and &lt;i&gt;in vitro&lt;/i&gt; digestion technique

The study was to provide the Chinese Feedbank with intestinal digestibility (Idg) of crude protein (CP) and AA for feedstuffs commonly used in China. The various AA of feedstuffs weren’t synchronously digested, while a larger variation was found in the same AA between feedstuffs. The CP Idg estimated by mobile nylon bag technique in soyabean meal, cottonseed meal, peanut cake meal, rapeseed meal, rice bran, maize germ meal, wheat bran and lucerne hay were 0.964, 0.813, 0.950, 0.826, 0.586, 0.793, 0.679 and 0.400, respectively. It has a strong correlation with the value obtained by three-step in vitro procedure.

Rumen and Post Abomasal Disappearance of Amino Acids and Some Nutrients of Barley Grain Treated with Sodium Hydroxide, Formaldehyde or Urea in Lactating Cows

Four rumen and duodenum cannulated, Holstein lactating cows were used in a change-over design to determine the effects of NaOH, Formaldehyde or Urea treated barley on disappearance of Dry Matter (DM), Crude Protein (CP), Amino Acids (AA), NDF, ADF, hemicelluloses and starch in rumen, Post Abomasal Tract (PAT) and total tract by mobile nylon bag technique. Experimental treatments were coarse milled barley, barley treated with 3.5% NaOH, barley treated with 0.4% formaldehyde and barley treated with 3.5% urea that all chemical treated barley milled coarse before feeding. NaOH Treatment reduced concentrations of Lysine and Cystine in the barley grain. All chemical treatments decreased rumen disappearances of barley CP but only NaOH and Formaldehyde treatments also decrease total AA and some of the AA disappearances in the rumen. All chemical treatments increased DM, OM, CP, starch, NDF, ADF and hemicellulose disappearance of barley in the PAT. But only NaOH and Formaldehyde treatments increased total AA and most of AA disappearances in the PAT. Effect of chemical treatments on increase of disappearance of starch, Met and Gly in the total tract was significant (p < 0.05). Rumen disappearance of TAA was lower than CP but PAT disappearance of TAA was more than CP and finally total tract disappearance of TAA was more than CP. Individual AA in barley disappeared at different rates in the rumen and PAT. Consequently, the proportion of digesta CP and AA entering the intestine must be considered.

Effects of microwave irradiation on ruminal protein degradation and intestinal digestibility of cottonseed meal

The objectives of this study were to determine the effects of microwave irradiation on ruminal degradability and intestinal digestibility of crude protein (CP) and to monitor the fate of true proteins of cottonseed meal (CSM) in the rumen. Duplicate nylon bags of untreated or irradiated CSM (microwave power of 800 W for 2, 4 and 6 min) were suspended in the rumen of four non-lactating Holstein cows for up to 48 h, and resulting data were fitted to non-linear degradation model to calculate degradation parameters of CP. Proteins of untreated and treated CSM bag residues were fractionated by gel electrophoresis. Intestinal digestibility of CP was measured using the mobile nylon bag technique. From in situ results, microwave irradiation decreased ( P < 0.05) the water soluble fraction and degradation rate, but increased the potentially degradable fraction of CP. The effective degradability of CP decreased ( P < 0.05) as processing period increased. Irradiation for 2 and 4 min increased ( P < 0.05) intestinal digestibility of ruminally undegraded CP, but extending to 6 min lowered ( P < 0.05) the beneficial effect that 4 min had on intestinal CP digestibility. Electrophoretic results indicated that globulin 9S in untreated CSM (whereas globulin 9S, globulin 5S and albumin 2S in microwave irradiated CSM) make the bulk of escaped protein. Based upon these results, microwave irradiation at a power of 800 W for 4 min had the greatest potential to increase digestible undegraded protein.

Effect of ethanol concentration on the kinetics of ruminal degradation of soybean meal

Effects of ethanol treatment on ruminal in situ degradation kinetics of dry matter (DM) and crude protein (CP) of soybean meal (SBM) were determined. Soybean meal samples were soaked in 500, 600 or 700 ml/l ethanol solutions for 2 h. Duplicate nylon bags of untreated or treated SBM were suspended in the rumen of four non-lactating Holstein cows for up to 48 h, and resulting data were fitted to non-linear degradation model to calculate degradation parameters of DM and CP. Intestinal CP digestibility was measured using the mobile nylon bag technique. Proteins of untreated and treated bag residues were fractionated by gel electrophoresis. There were differences (P<0.05) for DM and CP degradation parameters between untreated and ethanol treated SBM. Regardless of the concentration, ethanol treatments applied to SBM decreased the washout fraction, the estimated rate of CP degradation, and the effective protein degradation (EPD) compared to untreated SBM. The lowest estimated rate of CP degradation and the calculated EPD were observed when SBM was treated with 600 ml/l ethanol solution. Extending the ethanol concentration over 600 ml/l to SBM was considered excessive. Ethanol treatments increased (P<0.05) the intestinal mobile bag digestibility of ruminally undegraded CP. At concentration of 500, 600 and 700 ml/l, digestibility of CP increased by 4, 12 and 13% compared to untreated SBM, respectively. Electrophoretic analyses of untreated, 500, 600 and 700 ml/l ethanol treated SBM revealed that two of the subunits of β-conglycinin (ά and α) had been degraded completely after 2, 6, 8 and 8 h, whereas the β subunit of this protein has been degraded after 4, 8, 12 and 12 h, respectively. In untreated SBM, the acidic and basic subunits of glycinin had been degraded in 8 and 12 h of incubation, but in treated SBM had not been degraded even after 48 h of incubation. Based upon these results, treatment of SBM with 600 ml/l ethanol solution had the greatest potential to increase rumen undegradable protein.

Malic acid combined with heat treatment to protect protein from soybean meal against rumen degradation

The protection of proteins from soybean meal (SBM) by treatments with solutions of malic acid (at two crescent doses) and heat was studied in a 3 × 3 Latin-square design using three diets and three wethers cannulated in the rumen and in the duodenum. Solutions 2.25 and 4.50 N of malic acid were pulverised (400 mL·kg −1 ) on SBM under continuous mixing. Then, the treated meals were dried in an oven at 117 ◦ C for 6 hours. The diets were isoproteic and included 55% lucerne hay and 45% concentrate, with untreated (UT) and treated SBM (T2.25N and T4.50N). The diets were distributed, at 50 g·kg −1 BW 0.75 , in six equal meals (every 4 h). The estimates of ruminal effective degradability (ED) of dry matter (DM) and crude protein (CP) of SBM samples were obtained using in situ and rumen outflow methods, whereas the intestinal digestibility (ID) was determined by the mobile nylon bag technique on residues incubated in the rumen for 8 h. The effects of the addition of malic acid in the diet on rumen fermentation patterns and fibrolitic activity (measured by the in situ degradation of the lucerne hay) were also determined. The treatments did not alter the digestive transit kinetics of SBM particles, which showed rumen outflow rates in the interval from 5.5 to 6.1%·h −1 . Degradation of CP showed a sigmoidal shape in all samples and was described well with a simple exponential model, based on a constant fractional degradation rate (kd), or using a logistic model in which the fractional degradation rate increases with time from an initial (ko )t o afi nal (k∞) value. According to the first model, the kd value corresponding to the protective treatments showed a tendency (P = 0.054) to decrease with the treatments (from 4.71 to 3.32 and 3.35%·h −1 for UT, T2.25N and T4.50N, respectively). In the second model, this deceleration of CP degradation only affected ko (P = 0.039), whereas, no effect was observed on k∞. These changes reduced moderately the ED of CP of the treated samples (15-16%) in relation to the untreated SBM, although differences were not significant (46.2, 39.3 and 38.5%, respectively, as mean of both models). No effect was observed for the ID of CP with values shown between 99.0 and 99.4%. Including malic acid in the diet did not have an important effect on the degradation of DM and fibre fractions of lucerne hay or on the parameters of ruminal fermentation, except for a decrease (P = 0.050) of the acetic acid:propionic acid ratio (4.44, 3.53, and 3.78 for UT, T2.25N and T4.50N, respectively). protein protection / soybean meal / malic acid / heat / effective degradability / intestinal di- gestibility

Determination of undegradable intake protein digestibility of forages using the mobile nylon bag technique1

Two experiments were conducted using 2 ruminally and duodenally fistulated steers to determine the digestibility of undegradable intake protein (UIP) of smooth bromegrass (Bromis inermis), birdsfoot trefoil (Lotus coniculatus L.), and heat-treated alfalfa (Medicago sativa) using the mobile nylon bag technique. Undegradable intake protein was determined using neutral detergent insoluble CP at a single in situ incubation time point based on 75% of the total mean retention time estimated from IVDMD plus a 10-h passage lag. In Exp. 1, UIP (% DM) of smooth bromegrass in June and July were 1.82 and 1.71, respectively (P = 0.11). Undegradable intake protein (% DM) of birdsfoot trefoil increased from 1.30 in June to 1.94 in July (P < 0.01). Total tract indigestible protein of smooth brome-grass and birdsfoot trefoil increased in July (P < 0.05). Digestibility of UIP decreased in July for smooth brome-grass (P < 0.01) but tended to increase for birdsfoot trefoil (P = 0.07). In Exp. 2, alfalfa from plots fertilized with low (66 kg of N/ha) or high (200 kg of N/ha) amounts of N were dried to simulate 3 preservation methods: dehydrated (100 degrees C, 10 h), sun-cured (50 degrees C, 15 h), and lyophilized (-50 degrees C, 72 h) alfalfa. Undegradable intake protein (% DM) was estimated as in Exp. 1 and was 3.13, 2.10, and 1.84 for dehydrated, sun-cured, and lyophilized alfalfa, respectively. Total tract indigestible protein (% DM) was increased (P < 0.05) for dehydrated alfalfa (1.66) compared with sun-cured (1.54) or lyophilized (1.57) alfalfa. As a result of greater UIP flow to the lower tract, digestibility (%) of UIP was greater (P < 0.01) for dehydrated (46.4) than for sun-cured (25.6) or lyophilized (14.7) alfalfa. Heat-treated alfalfa samples increased net UIP absorption in the lower tract because 1.47, 0.56, and 0.27 percentage units of UIP (% DM) of dehydrated, sun-cured, and lyophilized alfalfa, respectively, disappeared. Overall, the digestibility of the UIP of these forages was low in the lower tract.

Protein value for ruminants of a sample of whole cottonseed

AbstractThe effective ruminal degradability (ED) of dry matter (DM), crude protein (CP) and amino acids, and the effective intestinal digestibility (IED) of DM and CP of a sample of whole cottonseed was measured using in situ and rumen outflow rate techniques in three wethers cannulated in the rumen and duodenum. The microbial contamination of rumen incubated residues was corrected by a continuous rumen infusion of15NH3as microbial marker and rumen solid associated bacteria as reference sample. Microbial contamination resulted in an overestimation of the undegradable fraction of DM (0·291v. 0·275;P&lt;0·05) and CP (0·071v. 0·037;P&lt;0·01) and a small underestimation of ED of DM (0·500v. 0·512;P=0·09) and CP (0·755v. 0·779;P=0·052). A proportion of 0·1 of the ruminal undegraded CP was of microbial origin and for essential amino acids this proportion varied from 0·042 to 0·150. Differences in ED between amino acids modified the amino acid profile, with an important reduction (0·2;P&lt;0·01) in the proportion of lysine. Apparent intestinal digestibility of the insoluble fraction of this food, measured with the mobile nylon bag technique, showed large reductions (P&lt;0·001) with the increase of the ruminal incubation time between 0 and 72 h: from 0·392 to 0·026 for DM and from 0·851 to 0·099 for CP. These evolutions fitted an exponential function with a previous lag. The IED was estimated either by integration of these equations and those describing the ruminal degradation and rumen outflow or by incubation through the intestines of a sample pooled to be representative of rumen flow of the undegraded food. The two methods gave similar values for both DM (0·222v. 0·203) and CP (0·659v. 0·658).

Post-ruminal digestibility of crude protein from grass and grass silages in cows

Grass samples were grown on a clay or sandy soil, fertilised with 150 or 300 kg N/ha per year, and harvested on different days during two consecutive growing seasons. The grass samples were stored frozen or ensiled after wilting to approximately 250 or 450 g DM/kg. The recoveries of crude protein (CP) after passing the rumen, the intestines and the total gastro-intestinal (GI) tract in grass and grass silages were determined with the two-step mobile nylon bag technique and a two-step in vitro technique, mimicking the rumen and intestine. Mobile nylon bag experiments were performed with 9 grass samples and 18 silages of the same grasses, pre-wilted to 250 or 450 g DM/kg. The in vitro experiments were performed with a series of 112 samples (54 grass and 58 grass silage samples). Both the in situ and in vitro results showed that the intestinal recoveries of CP were largely influenced by the amount of rumen-undegraded protein (RUP). A high value of RUP was compensated by an enhanced digestibility in the small and large intestine, resulting in a rather constant recovery of CP after passage through the total gastro-intestinal tract. It is suggested that residual CP after total tract passage is protein that is interwoven in the cell wall construction, cell wall bound or of microbial origin.

Digestion of Feed Amino Acids in the Rumen and Intestine of Steers Measured Using a Mobile Nylon Bag Technique

The disappearance of dry matter (DM), crude protein (CP), and amino acids (AA) in steers after rumen incubation and intestinal passage of alfalfa hay, barley hay, corn silage, barley grain, corn grain, wheat bran, meat meal, fish meal, cottonseed meal, and soybean meal were measured in 3 steers using a mobile nylon bag technique. Ruminal degradation of individual AA differed between feedstuffs. For barley hay and corn silage, the ruminal disappearance of total AA was higher and lower than the other feedstuffs, respectively. The intestinal digestibility of total AA in alfalfa hay was lower than the digestion of CP. The intestinal digestibility of Arg and His was higher than that of total AA in alfalfa hay, meat meal, cottonseed meal, soybean meal, barley hay, and wheat bran. In addition, the intestinal digestibility of Lys was higher than that of total AA in alfalfa hay, meat meal, cottonseed meal, soybean meal, barley hay, corn silage, and wheat bran. The intestinal disappearance of CP in most cases was higher than that of DM. The results indicated that feedstuffs with lower ruminal disappearance of DM, CP, total AA, essential AA, and nonessential AA generally had a higher intestinal disappearance, resulting in a relatively constant total tract disappearance. These results could be used to improve the current system of diet formulation in ruminants.

Validation of the cannulated pig model for determining intestinal nutrient disappearance in cattle

The mobile nylon bag technique was used to determine the potential of cannulated pigs to model intestinal dry matter (DM) and crude protein (CP) digestibility of ruminal undegradable residues (RUDR) of various feed samples in cattle. A total of 11 feeds (six protein supplements and five forages) varying in rumen degradability were utilized: canola meal (regular vs. heated); soybean meal (regular vs. heated); distillers’ grains (regular vs. heated ); alfalfa hay (regular vs. dehydrated alfalfa pellets); barley silage (regular vs. heated); and barley straw. Ruminal undegradable residues of each feedstuff were placed into eight polyester bags and inserted into the duodenum of two cannulated Hereford steers (644 ± 14 kg). Another eight bags for each RUDR sample were randomly allocated to six crossbred gilts (Camborough 15 line female × Canabred sire; 50 ± 1.2 kg body weight) and inserted into the pigs’ duodenum via duodenal cannulas. Bags were recovered in the feces from both the cattle and pigs. Regression analysis was used to relate intestinal DM and CP digestibility obtained in pigs with those obtained in steers. Intercepts not different from zero were forced through the zero intercept to obtain a measure of bias and loss of precision resulting from forcing the zero intercept. The non-zero regression equations relating steer estimates to those obtained from pigs were -3.17 + 0.95 X [r2 = 0.98, residual standard deviation (RSD) = 3.84] and 0.35 + 0.96 X (r2 = 0.98, RSD = 6.16) for DM and CP disappearance, respectively. Forcing the non-zero intercept resulted in pigs over predicting intestinal DM disappearance in cattle by 10.6% with a RSD of 4.30. Using the pig model, intestinal CP disappearance of cattle was over predicted by 3.1% with a RSD of 5.85. It was concluded that pigs can be used to model intestinal DM and CP disappearance of ruminal undegraded feed residues in cattle. Key words: Cattle, pigs, mobile nylon bag technique, intestinal nutrient availability

Prediction of the chemical composition of winter grain and maize with near infrared reflectance spectroscopy

Near infrared reflectance spectroscopy (NIRS) was evaluated as a tool for the fast and inexpensive prediction of nutritional values of feedstuffs. NIRS calibrations were developed for winter grain samples collected over three years in the Western Cape region of South Africa. Winter grains used in the study include oats, barley, triticale and wheat. Calibrations were also developed for maize samples collected throughout South Africa. Win- ter grain samples were analysed for ash, dry matter (DM), crude protein content (CP), fat content, acid detergent fibre (ADF), neutral detergent fibre (NDF), in vitro organic matter digestibility (IVOMD), lysine and methionine. The digestible energy (DE) content of winter grain samples was determined by the mobile nylon bag technique on pigs. Maize samples were analysed for ash, DM, CP, IVOMD and TDN (total digestible nutrients). Standard errors of prediction (SEP) and multiple correlation coefficients (r) for the different winter grain constituents were respectively; ash (0.22%; 0.87), DM (0.67%; 0.68), CP (0.60%; 0.93); fat (0.19%; 0.99), ADF (0.88%; 0.98), NDF (2.13%; 0.97), IVOMD (2.06%; 0.97), DE (0.76%; 0.91), lysine (0.04%; 0.93) and methionine (0.01%; 0.90). SEP and r values for the maize calibrations were, ash (0.08%; 0.49), DM (0.12%; 0.95), CP (0.12%; 0.95), IVOMD (0.55%; 0.92) and TDN (0.39%; 0.92). These results suggested that NIRS can be developed as a rapid and accurate tool for the prediction of the nutritional value of feedstuffs, which makes it an attractive technique for routine quality control in the industry.

Effect of diet composition and feeding pattern on the prececal digestibility of starches from diverse botanical origins measured with the mobile nylon bag technique in horses1

This trial was conducted to determine the extent of prececal starch digestibility depending on the botanical origin of starch and on diet characteristics (i.e., composition and feeding pattern). The prececal disappearance of six substrates (oats, barley, corn, horse bean, potato, and wheat) was measured in four cannulated horses fed (as-fed basis) 11.8 g/kg BW of a high-fiber (HF) or high-starch (HS) pelleted feed and 10.0 g/kg BW of meadow hay using the mobile bag technique (MBT). The daily feeding pattern was either three meals (two meals of pellets and one meal of hay) or five meals (three meals of pellets and two meals of hay). The experimental procedure was a 2 x 2 factorial arrangement tested in a Latin square design. After 2 wk of adaptation to the diet, collections were made on 5 d. Thirty nylon bags, composed of five bags of each substrate, were intubated to each horse during the ingestion of the morning meal. Bags were collected in the cecum, using a magnet, at 9 h postintubation. In spite of strong interindividual differences, approximately 80% of the intubated bags were collected. On average, the mean retention time of the bags was 6.2 h (+/-0.17). Regardless of the feeding pattern, the transit of the bags was faster when the fiber content of the diet was higher (P = 0.003). Likewise, regardless of the meal composition, transit was also faster when the ration was split into five daily meals (P = 0.001). The DM disappearance, corrected with particulate losses (DMD(c)), differed depending on the substrate tested (33.5, 57.1, 63.8, 67.7, 78.6, and 86.2% for potato, horse bean, oats, barley, corn, and wheat, respectively; P = 0.001). The DMD(c) of corn, barley, and potato was higher when HS was fed (P = 0.020); regardless of the substrate, DMD(c) was higher with five daily meals (P = 0.001). The starch disappearance (StarchD(c)) was different depending on the substrate (P = 0.001; 36.1, 71.2, 86.6, 89.2, 99.0, and 99.7% for potato, horse bean, barley, corn, wheat, and oats, respectively). Whatever the substrate, StarchD(c) was higher when HS was fed (P = 0.007), but it was not affected by the feeding pattern of the diet. Although passage rate was modified and feed intake was different, the botanical origin of starch was the main factor that affected prececal starch disappearance in horses.

Use of the mobile nylon bag technique to determine the digestible energy content of traditional and non-traditional feeds for swine

The following experiment was conducted using the mobile nylon bag technique (MNBT) to determine dry matter and energy digestibility in traditional feeds as well as non-traditional feeds in order to calculate digestible energy (DE) values for use in ration formulation programmes. A total of 22 ingredients were tested in this experiment including the traditional cereal grains barley, corn, oats and wheat, as well as secondary cereal grains such as normal and low viscosity rye, low lignin and high fat oat groats, wheat heavies and # 1 wheat screenings and a new bread wheat designated as CDC Teal. Three legumes (lupines, peas and dehydrated alfalfa), three varieties of canary seed (CDC Maria, dehulled CDC Maria and Keet), and raw and micronized canola seed were tested as protein sources. Finally, three oilseed meals obtained from the Chinese feed industry (Chinese rapeseed meal, Chinese cottonseed meal and extruded full-fat soybean meal) were also included. After simulating gastric digestion the nylon bags were inserted into the duodenum of five barrows through simple duodenal T-cannulae. Eight bags were administered to each pig daily. Ten nylon bags were prepared for each feed with two bags being inserted into each of the five barrows. A total of 220 bags were inserted over a 7-day period. The overall results of this experiment indicate that the MNBT has great potential for use in determining the digestible energy content of swine feeds. For the most part, values obtained in the present experiment compared favourably with previously published values. Four feedstuffs produced digestible energy values that differed by greater than 5% from previously reported values. However, variation in chemical content provided a reasonable explanation for these discrepancies. The MNBT has several advantages compared with conventional digestibility methods in that many feeds can be tested in a relatively short duration of time with significantly fewer animals being used, only small amounts of feed are required and the test allows for energy measurements in feedstuffs that would not normally be fed to pigs as a single ingredient. Additional research on a wider variety of feedstuffs should be conducted to confirm the potential of the MNBT as a tool to accurately determine DE values for swine.

Protein and Amino Acid Digestibility in Dairy Cows Measured with Mobile Nylon Bags Recovered in Ileum or in Faeces

Digestibility of protein and amino acids in dairy cows was measured using the mobile nylon bag technique and collection of bags in ileum and in faeces. The feeds studied were untreated and expander treated barley and oats, solvent extracted rapeseed meal (RSM) and soybean meal (SBM), lignosulfonate treated SBM (SoyPass) and fish meal (FM). The nylon bags were recovered in ileum by trapping the bags with a magnet. The functionality of the technique was considered good although a metallic slice in the bags increased intestinal retention time. Compared to intact feed, pre-incubation 16 hours in the rumen increased digestibility of dietary protein and amino acids. The indigestible residues were in general lower in bags recovered in faeces than in ileum. In addition, some variation in digestibility among amino acids within feedstuffs seems to exist. The general conclusion was that the procedure of collecting bags in ileum can be skipped when digestibility of protein and amino acid is determined on rumen pre-incubated feed, but not when intact feed is used. Except for increased digestibility in intact barley, no major effect of expander treatment or lignosulfonate treatment on digestibility of protein and amino acids was found.

Variation in the chemical composition, physical characteristics and energy values of cereal grains produced in the Western Cape area of South Africa

Grain samples were produced at 10 different locations in the Western Cape region of South Africa, on 2.1 m x 6 m experimental plots, over a period of three years. Twenty different cereal grain cultivars were used in the study. A randomised square experimental design with four replicates per sample was used. An area of 1.35 m x 5 m from each plot was harvested during 1994, 1995 and 1996 and the yield was determined. Thousand seed mass (TSM) and hectolitre mass (HLM) were also determined. Samples were analysed for dry matter (DM), ash, crude protein (CP), ether extract (EE), neutral detergent fibre (NDF), acid detergent fibre (ADF) and in vitro organic matter digestibility (IVOMD). Digestible energy values (DE) for pigs were determined with a mobile nylon bag technique, while non-structural carbohydrate values (NSC) were calculated. In the first analysis, cultivars were compared by a one-way analysis of variance, followed by pooling of grain type data. Naked oats had the highest DE value, and the respective values (DM basis) for naked oats, wheat, triticale, 2-row brewer's barley, 6-row feed barley and oats were 18.0, 16.0, 15.8, 14.9, 14.4, and 12.6 MJ/kg DM. The high EE value of naked oats (97 g/kg) might be partly responsible for the high DE value. The 6-row and 2-row naked barley cultivars had the highest IVOMD (946 g/kg and 944 g/kg), followed by wheat (910 g/kg), triticale (905 g/kg), naked oats (899 g/kg), 2-row brewer's barley (882 g/kg), 6-row feed barley (844 g/kg) and oats (671 g/kg). Considerable variation was found between samples within a cultivar for DE and IVOMD. Two-row naked barley had the highest mean CP value (159 g/kg) followed by naked oats (159 g/kg), 6-row naked barley (154 g/kg), wheat (148 g/kg), triticale (146 g/kg), oats (143 g/kg), 2-row brewer's barley (136 g/kg) and 6-row feed barley (135 g/kg) on DM basis. Triticale had the highest yield, with naked oats and barley cultivars having the lowest yield. Keywords: Cereal grains, Chemical composition, Energy value South African Journal of Animal Science Vol.33(2) 2003: 117-126

Digestible dry matter and protein of lucerne hay or lucerne silage treated with sulphuric acid using mobile nylon bag technique

Legume forages, because of the tubular and hollow stem structure, low soluble sugar content and high buffering capacity are less likely to undergo otpimal fermentation. Therefore, response to silage additives (such as formic acid) or preservatives may be great with legume forages. This study was conducted to evaluate the DM and protein digestibility of lucerne hay or lucerne silage treated with urea and/or sulphuric acid using mobile nylon bag technique.

Ruminal and intestinal protein disappearance of some tropical (Iranian) feeds used in dairy cow diets estimated by the mobile nylon bag technique

In Iran milk production, in dairy cows, is based mainly on intensive systems in which cereals and industrial by-product are the most important source of nutrients. So, high digestible protein feeds are often desired for supplementation of high producing dairy cows to meet their amino acid requirements. Incubation of feeds in nylon bags in the rumen of fistulated ruminants have been used to evaluate the extent of digestion. In addition, the mobile bag technique has been used to measure intestinal digestibility of undegraded dietary protein and intact feed protein (Mesgaran, 2002). The work described in this summary assessed the digestibility of dry matter and protein, using ruminal and intestinal mobile nylon bag technique, of some tropical (Iranian) feeds used in dairy cow diets.

Rumen degradability and post-ruminal digestion of dry matter, nitrogen and amino acids in three tropical forage legumes estimated by the mobile nylon bag technique

The ruminal degradability and intestinal digestibility of dry matter (DM), nitrogen (N) and amino acids (AA) in whole plants of tropical forage legumes were estimated in three rumen and duodenal cannulated non-lactating Holstein/Friesian cows using the mobile nylon bag method. The legume samples were incubated in the rumen for 12, 24 and 48 h. After rumen incubation, the mobile bags were pre-incubated in pepsin–HCl solution before inserting into the duodenum and recovering in the faeces. Rumen DM degradabilities of cassia and of siratro were greater than that of lablab and increased with increasing rumen incubation time. The post-ruminal digestibility of undegraded DM was not different between the legumes. Similarly, N degradability was not different among the three legumes after similar incubation periods. However, the intestinal digestibility coefficients of rumen undegradable N in cassia and siratro were greater than that of lablab. The digestibility of total amino acids varied between 0.346 and 0.771. The digestibility coefficients of essential amino acids and non-essential amino acids followed a trend similar to that of total amino acids. Siratro showed the highest digestibilities of individual amino acids, total amino acids and nitrogen with cassia being intermediate and lablab the least. These results indicate that undegraded legume proteins differ as sources of absorbable amino acids in the small intestines.