Duodenal Flow Research Articles

Milk quality of ruminants fed with tannin-based diets

Tannins are found in various feeds and can produce numerous benefits to ruminants, such as preventing bloat, favoring a better use of dietary protein, increasing microbial protein synthesis, according to its concentration, molecular weight and structure. The tannins affect the digestibility of the protein, because they form complexes with dietary proteins, improving the duodenal flow of proteins, of some essential amino acids and of unsaturated fatty acids, modifying the profile of two fatty acids of meat and milk and age in rumen biohydrogenation, They provide faster growth rates of live weight, higher milk production, increased fertility and reduction of the parasite load, improving the animal's well-being and health. The nutritional effects of two tannins may vary according to the type of tannin used and the level of inclusion in the diet, its chemical structure and molecular weight, the quantity ingested, the species or animal category involved and the energy and protein balance of the diet.

Effect of substituting grass-clover silage with maize silage for dairy cows on nutrient digestibility, rumen metabolism, enteric methane emission and total carbon footprint

The aim of this experiment was to determine the optimal ratio between maize silage and grass-clover silage in lactating dairy cow diets. The evaluation was based on nutrient digestibility, rumen metabolism and total carbon footprint (CF). Carbon footprint included enteric methane emission and CF from feed production, transportation, processing, and C sequestration in the soil, based on a Life Cycle Assessment (LCA) approach. Four diets varying in proportions of grass-clover silage and maize silage (100:0, 67:33, 33:67, and 0:100 on dry matter (DM) basis, respectively) were fed ad libitum to 4 lactating Holstein cows (a fifth cow was involved later in the study) fitted with ruminal, duodenal, and ileal canulae in a 4 × 4 Latin square design. Nutrient digestibility was measured using chromium oxide and titanium oxide as flow markers, and methane and CO2 emissions were measured in open-circuit respiration chambers on 5 consecutive days for each cow in each period. Data were analyzed with treatment and period as fixed effects and cow as random effect. DM intake (DMI) increased linearly (P = 0.01) with increased proportion of maize silage in the feed ration. Under the conditions in the present study, diets had only minor effects on digestibility of nutrients and there was no influence on rumen pH. Total VFA concentration decreased linearly with increased level of maize silage, but there were only minor effects on molar proportions of VFAs in the rumen. However, there was a linear increase in duodenal flow of microbial DM with increasing level of maize silage. The cows produced 30.7, 29.4. 28.4, and 26.2 L of methane/kg of DMI on diets 100:0, 66:33, 33:66, and 0:100, respectively (P = 0.02 for linear effect), which is equivalent to a 15% decrease, when all grass-clover silage was replaced by maize silage. Despite the significant reduction in enteric methane emission with increased proportion of maize silage, only a 4% decrease in total CF per kg DMI was found, when including CF from feed production, transportation, processing, manure, energy use and C sequestration in the soil, when using a LCA approach. If direct Land Use Change (LUC) or indirect LUC was included in estimation of CF, the reduction in CF when replacing all grass-clover silage was also 4–6%. However, the total CF was highly dependent on assumptions related to yield of grass-clover and maize.

Effects of hempseed cake on ruminal fermentation parameters, nutrient digestibility, nutrient flow, and nitrogen balance in finishing steers.

Five ruminally and duodenally cannulated red angus steers (n = 5; initial body weight [BW] = 542 kg, SD = 40 kg) were used in a three-period Youden square design consisting of three 21-d periods, three treatments, and five steers (one or two steers per treatment within each period) to evaluate the effect of feeding hempseed cake on ruminal fermentation parameters, organic matter (OM) intake, total tract nutrient digestion, and nitrogen (N) balance in steers fed finishing diets. The control (CON) diet contained 75% dry-rolled corn, 20% corn silage, and 5% supplement (DM basis). The dried corn distillers grains plus solubles (DDGS) and hempseed cake (HEMP) diets contained 55% dry-rolled corn, 20% corn silage, 20% dried corn distillers grains plus solubles or hempseed cake, and 5% supplement (DM basis). Total ruminal volatile fatty acid concentration was greater (P < 0.01) in steers fed the HEMP diet than in steers fed the DDGS or CON diets. Ruminal fluid pH was not influenced (P = 0.93) by treatment. Organic matter intake tended (P = 0.07) to be greater and OM total tract digestibility was less (P = 0.03) in steers fed the HEMP diet compared with steers fed the DDGS or CON diets. Ruminal true and total tract apparent N digestibility was greater (P < 0.01) in steers fed the HEMP diet than steers fed the DDGS or CON diets. Duodenal flow of essential, nonessential, and total amino acids was not influenced (P ≥ 0.37) by dietary treatment, but the lack of response was likely because ruminally degradable protein (RDP) supply exceeded the RDP requirement. Steers fed the HEMP diet had greater (P < 0.01) N retention (g/d) than steers fed the DDGS diet, which was greater (P < 0.01) than steers fed the CON diet, suggesting that feeding hempseed cake improved utilization of N. Although inclusion of hempseed cake decreased total tract OM digestibility compared with dried corn distillers grains or corn, improvements in N utilization suggest that hempseed cake could be a useful alternative feed ingredient for finishing cattle diets.

Effect of dietary concentrate level on digestibility of nutrients in each region of the gastrointestinal tract and rumen fermentation in goats

This study evaluated the effects of high concentrate diets (HCD) on the rumen fermentation and the digestibility of nutrients in different sites of the gastrointestinal tract (GIT) in goats. Four goats were used in a crossover design. The goats were fitted with a ruminal cannula and flexible T-cannulae proximal duodenum and terminal ileum. Treatments were as follows: low concentrate group (LCG) and high concentrate group (HCG). Duodenal flow and forestomach digestibility of starch were significantly higher in the HCG than those in the LCG (p < 0.05); There was no significant difference in ileum flow and digestibility of starch in the small intestine, large intestine and total GIT (p > 0.05). The digestibility of crude protein (CP) in the forestomach was significantly higher in the HCG than in the LCG (p < 0.05); the flow of the duodenum and ileum of CP, and the CP digestibility of the small intestine, large intestine and total GIT were not significantly different between groups (p > 0.05). The duodenal and ileal flow of neutral detergent fiber (NDF), the NDF digestibility of the different segments and total GIT were not significantly different between groups (p > 0.05). Compared to the LCG, the ruminal pH of the HCG was significantly lower (p < 0.05). The HCG concentrations of microbial crude protein, ammonia nitrogen and isovaleric acid were significantly higher (p < 0.05) than the LCG. The foam strength, foam production and viscosity of the rumen fluid in the HCG were higher than the LCG (p < 0.01). These results showed that when the goats were fed with HCD, the digestibility of nutrients was not significantly impaired, but the risk of frothy rumen bloat increased. Implications Due to a serious shortage of high-quality roughage in China, producers commonly used a high-concentrate diet in ruminants, which can improve animal production performance. Gastrointestinal digestive function plays a vital role in the absorption of nutrients and the healthy growth of animals. Therefore, this research evaluated the digestibility of various nutrients in different segments of the gastrointestinal tract (GIT) under HCD feeding by using three-site cannula goats as experimental animals. The results indicated that the GIT of goats could fully digest nutrients such as starch and protein under HCD feeding conditions.

Impacts of added roughage on growth performance, digestibility, ruminal fermentation, and ruminal pH of feedlot steers fed wheat-based feedlot diets containing 30% modified distillers grains with solubles.

Two experiments were conducted to evaluate the inclusion rate roughage in wheat-based diets containing modified distillers grains with solubles (MDGS) on feedlot performance (Feedlot Experiment), as well as digestibility, ruminal pH, and ruminal fermentation characteristics (Digestibility Experiment). The feedlot experiment utilized 72 Angus steers (392 ± 46.3 kg initial body weight) which were randomly assigned to 1 of 12 pens, 3 pens per treatment, to evaluate feedlot performance and carcass characteristics. Dietary treatments were 1) control; 10% roughage, 2) 12% roughage, 3) 14% roughage, and 4) 16% roughage. The digestibility experiment used four ruminally and duodenally cannulated steers (393 ± 33.0 kg) in a 4 × 4 Latin Square with either 10%, 12%, 14%, or 16% roughage as in the feedlot experiment. However, dietary roughage source was different between these two experiments and included a combination of grass hay and wheat straw (Feedlot Experiment), and corn silage (Digestibility Experiment). All data were analyzed with the Mixed Procedures of SAS. Feed intake was recorded, with duodenal and fecal output calculated using chromic oxide. Ruminal pH and fermentation were assessed. Growth performance and most carcass characteristics were not affected by increasing roughage (P ≥ 0.11). Marbling tended to decrease linearly (P = 0.10) with increasing roughage inclusion. Increasing dietary roughage content had no effect on organic matter intake (P = 0.60) in the digestibility experiment. Intake, duodenal flow, and digestibility of neutral detergent fiber and acid detergent fiber were not affected by treatment (P ≥ 0.16). Ruminal pH increased linearly (P < 0.01) as rate of roughage inclusion increased. Ruminal concentrations of acetate and butyrate increased, and propionate decreased in a linear fashion (P < 0.01) thereby increasing (P < 0.01) acetate and butyrate to propionate ratio with increasing dietary roughage. Our data indicate that increasing roughage inclusion in wheat-based diets including 30% MDGS increased ruminal pH and shifted ruminal fermentation patterns. Additionally, increasing roughage inclusion did not affect feedlot performance in steers fed wheat at 36% to 42% of dietary dry matter in combination with 30% MDGS.

Effects of corn grain endosperm type and fineness of grind on site of digestion, ruminal digestion kinetics, and flow of nitrogen fractions to the duodenum in lactating dairy cows

Our objective was to evaluate effects of corn grain endosperm type and fineness of grind on feed intake, feeding behavior, and productive performance of lactating cows. Eight ruminally and duodenally cannulated Holstein cows in mid lactation (130 ± 42 d in milk; mean ± standard deviation) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used with main effects of corn grain endosperm type (floury or vitreous) and fineness of grind (fine or medium). Rations included alfalfa silage, corn treatments, protein supplement, minerals, and vitamins and were formulated to contain 29% starch, 27% neutral detergent fiber, 18.2% forage neutral detergent fiber, and 18% crude protein. Corn grain treatments supplied 86.2% of dietary starch. Endosperm was 25% vitreous for the floury treatment and 66% vitreous for the vitreous treatment. The floury treatment increased rate of starch degradation by 94% (19.2 vs. 9.9%/h) and decreased rate of starch passage by 38% (16.1 vs. 25.8%/h), increasing apparent ruminal starch digestibility by 117% (53.7 vs. 24.7%). The floury treatment increased total-tract starch digestibility by 8% (92.2 vs. 85.1%) despite 37% lower postruminal starch digestion for the floury treatment compared with vitreous corn (38.4 vs. 60.7% of starch intake). Fine grind size increased apparent ruminal starch digestibility by 52% (47.2 vs. 31.1%) compared with medium grind size by increasing the rate of starch degradation by 105% (19.5 vs. 9.5%/h) with no effect on rate of starch passage. However, total-tract starch digestibility was not affected by fineness of grind because postruminal starch digestibility was 37% greater for medium compared with fine grind size (57.2 vs. 41.9% of starch intake). Endosperm type did not affect flow of nitrogen (N) fractions to the duodenum or microbial N efficiency, whereas fine grind size increased duodenal flow of nonammonia N by increasing duodenal flow of microbial N by 22% compared with medium grind size (438 vs. 359 g/d) but did not affect apparent total-tract N digestibility. No interactions were detected for any measure of starch digestion, ruminal N metabolism, or flow of N fractions to the duodenum. Endosperm type greatly affected ruminal and total-tract starch digestibility independent of the fineness of grind of corn grain with no effects on flow of N fractions.

Influence of unsaturated to saturated ratio of fatty acids reaching the duodenum on postruminal digestion of stearic acid in Holstein steers fed a high-fat finishing diet.

Objective:To evaluate the influence of the unsaturated to saturated ratio of fatty acids (FAs) reaching the duodenum on postruminal digestion of FAs, mainly focused on stearic acid (C18:0).Materials and Methods:Six Holstein steers [208 ± 3 kg initial live weight (LW)] with cannulas in the abomasum and proximal duodenum were used in a replicated 3 × 3 Latin square design. Steers were fed a fixed amount of a basal steam-flaked corn-based diet containing 8% supplemental fat and were daily infused via abomasum with 0, 67, and 165 gm oleic acid (C18:1). The experiment lasted for 42 days.Results:The daily total FA (TFA) intake (dietary FA intake plus abomasal infusion of oleic acid) represented a 1.78, 2.10, and 2.56 gm TFA/kg LW ratio. The unsaturated to saturated ratio of FAs entering the duodenum increased (p < 0.01) as level C18:1 infusion into the abomasum increased. Infusion of C18:1 tended (quadratic component, p = 0.07) to improve postruminal TFA digestion, being maximal for the 67 gm/day infusions. This increase in TFA digestion was due to increased (quadratic component, p = 0.03) postruminal C18:0 digestion (postruminal digestion of the other FAs was not different, p ≥ 0.13). Conclusion:Increasing the unsaturated to saturated ratio of FAs entering the small intestine will enhance intestinal C18:0 digestion. This positive effect is expected to be more likely beneficial when FA intake is high (and thus, the duodenal flow of FA is high), but this benefit looks diminished when the quantity of TFA reaching the intestine exceeds the proportion of 2.13 gm FA/kg LW.

347 Choosing an external marker for measuring intake and digestibility in ruminants

Abstract Proper nutrition is key to maintaining and improving animal productivity. Measuring intake and site and extent of digestion is essential for appropriate diet formulation. However, it is extremely difficult to accurately account for the dynamic nature of the ruminant digestive tract. External markers have long been used as a tool to measure digesta output, yet proper marker selection can be challenging. The aim of this review is to provide guidance in the selection of external markers in ruminant nutrition studies. External markers must satisfy certain requirements in order to be considered a valid marker. These requirements include, but are not limited to, being inert in the gastrointestinal tract, mixing with the digesta, and having high recovery rate in the feces. In addition, laboratory analysis needs to be easily reproducible within and amongst laboratories. Health hazards of the marker must also be kept in mind for the laboratory worker and the animal. There are a number of elements that have been utilized as external markers. Currently in the literature, chromic oxide (Cr2O3), long-chain alkanes (C32 to C36) and titanium dioxide (TiO2) are the most commonly used external markers. Each have been extensively evaluated and have their own positive and negative attributes. Results comparing fecal recoveries has been extensively reported in various diets fed to large and small ruminants. Of the three most widely utilized external markers, all have demonstrated adequate fecal recoveries, reasonable estimates of total duodenal and fecal digesta flows or output. Therefore, the selection of the appropriate marker comes down to the ease and accuracy at which analysis can be conducted, dosage rate, minimum dosage frequency, and safety to the user and animal.

The effects of 2-hydroxy-4-methylthio-butanoic acid supplementation on the rumen microbial population and duodenal flow of microbial nitrogen

Four multiparous, lactating Holstein cows (average DIM 169.5 ± 20.5 d), fitted with ruminal and duodenal cannulas, were used in a 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments to investigate the effects of 2-hydroxy-4-methylthio-butanoic acid (HMTBA) when fed with diets differing in metabolizable protein (MP) supply and equal levels of crude protein on milk production and composition, rumen microbial activity, duodenal protein flow, and rumen bacterial community composition in vivo and in vitro. Experimental periods were 28 d in length. Cows were housed in individual tie stalls and were randomly assigned to 4 dietary treatments: low MP or high MP, supplemented with or without 25 g of HMTBA, which was top-dressed once daily at 0930 h. No interactions were observed between HMTBA and level of dietary MP, with the exception of ruminal acetate-to-propionate ratio. Milk yield was not affected by treatment and averaged 23.8 ± 2.06 kg/d. There was a tendency for increased milk protein percent in cows receiving low MP diets, averaging 3.30 ± 0.09% and 3.21 ± 0.09% for low MP and high MP, respectively. The total-tract apparent digestibility of organic matter, neutral detergent fiber, and nitrogen were greater in cows consuming the low MP diet. Rumen pH was lower in cows consuming high MP diets as well as in those consuming HMTBA. Rumen ammonia concentrations tended to be greater in cows consuming HMTBA, and volatile fatty acid concentrations were greater in cows consuming HMTBA. Duodenal dry matter flow, nitrogen flow, and microbial nitrogen flow did not differ between treatments. The bacterial community structure of cows receiving HMTBA was not affected at the phylum level. The relative abundance of bacterial phyla in vivo differed when compared with in vitro conditions for Firmicutes, Bacteroidetes, Proteobacteria, TM7, Tenericutes, Spirochaetes, SR1, and Verrucomicrobia.

Effect of forage source and dietary rumen-undegradable protein on nutrient use and growth in dairy heifers

Thirty-two Holstein heifers with mean (± standard error of the mean) age of 6.5 months (±0.12) and live weight (LW) of 166 kg (±1.6) were divided into four groups of eight animals to evaluate the effect of forage source and the concentrations of rumen-undegradable crude protein (RUP) in the diet with a 2 × 2 factorial design. As forage sources cowpea hay (Vigna sinensis L.) or pangola grass hay (Digitaria decumbens Stend) were added to the diet at 250 g/kg dry matter (DM). Also, 350 g/kg DM of chopped fresh King grass (Pennisetum purpureum Schum.) was included in all diets. The RUP proportions were 260 or 360 g/kg of total crude protein (CP). Heifers were housed in metabolism cages. The trial lasted ten weeks, with the first two weeks used for adaptation and the last week for data collection and sampling. Diets had a forage to concentrate ratio of 60:40 (on DM basis), and were offered as total mixed rations ad libitum. Fish meal or urea were used to produce varying concentrations of RUP at similar dietary CP content. Diet ingredients (i.e., hay, grass, and concentrate) and feces were sampled for nutrient analysis. Total collection of feces was performed to estimate apparent total tract nutrient digestibility (ATTD). Urinary purine derivative excretions were determined from urine spot samples to estimate rumen microbial protein synthesis. The effects of forage source, RUP, and its interactions were determined by general linear model analysis. Replacing dietary pangola grass hay with cowpea hay increased daily intakes of DM, organic matter, CP, acid detergent fiber (ADF), and digestible organic matter, and ATTD of DM, organic matter, neutral detergent fiber, and ADF (P < 0.05). Duodenal flow of RUP also increased when substituting cowpea hay for pangola grass hay (P < 0.01). Similarly, inclusion of cowpea hay in the diet improved live weight gain (LWG; P < 0.05), and decreased feed costs per kg of LWG (P < 0.01). The increase in RUP decreased rumen microbial protein synthesis (P < 0.01), but tended to increase LWG, feed conversion and nitrogen use efficiency, and feed costs per unit of LWG (P < 0.10). The use of cowpea hay in the diet of dairy heifers increases nutrient intake and ATTD, leading to improved LWG and lower feed costs per kilogram of LWG. Increasing RUP proportions may reduce rumen microbial protein synthesis, but may enhance LWG, feed conversion efficiency, and nitrogen use efficiency. There were no interactions between forage source and RUP proportion on intake and ATTD, but some synergistic effects were observed for the performance parameters.

Short communication: A pilot study to describe duodenal and ileal flows of nutrients and to estimate small intestine endogenous protein losses in weaned calves

The aims of this pilot study were (1) to evaluate the effect of an ileal and duodenal cannulation surgery on body weight and dry matter intake, (2) to estimate endogenous losses of crude protein (CP) and AA in the small intestine, and (3) to describe duodenal and ileal flows of nutrients in weaned dairy calves. Three Holstein male calves were fitted at 7 wk of life with a T-cannula at the terminal ileum and another cannula at the proximal duodenum. On wk 14 of life, calves were randomly assigned to a single 3 × 3 Latin square with 10-d periods. The 3 diets were fed ad libitum and consisted of a control calf starter (CS) with conventional soybean meal (SBM) as the main source of protein (CTRL), an isonitrogenous (20% CP) CS with an enzyme-treated SBM as the main source of protein (ENZT), and a CS with low content of CP (10%) and no soy protein (LOCP). Flows and digestibilities of nutrients were compared between the soy-based high-protein diets (HICP) and LOCP, and between CTRL and ENZT. Final data were only available from 2 calves per diet (n = 2) because cannulas from 1 calf became inoperative after the first collection period. Duodenal flows of CP, total AA, nonprotein nitrogen, microbial N, and fatty acids, as well as apparent duodenal digestibility of starch, were greater for HICP than for LOCP, indicating a greater foregut microbial activity and digestion. The apparent ileal digestibility (AID) of organic matter, CP, and total AA were greater for HICP than for LOCP. Duodenal net flow of CP was greater for ENZT than for CTRL, but flow of AA was not different. On the other hand, duodenal flow of microbial N was greater, and flows of nonprotein N and starch were lower for the ENZT diet, suggesting a more efficient microbial activity in the rumen. Even though CTRL had a greater AID when compared with ENZT, the AID of CP and AA were greater for enzyme-treated SBM than for SBM. Endogenous losses in the small intestine per kilogram of duodenal dry matter flow were 47 ± 15 and 37 ± 12 g/d, and the true ileal digestibilities for the HICP diets were 86 ± 0.1 and 87 ± 0.1% for CP and AA, respectively. An optimal supply of CP and the inclusion of an enzyme-treated SBM improved the efficiency of microbial digestion and increased AA absorption. Although further research with greater biological replication is needed, our results indicate that there is potential to improve digestion and absorption of proteins through dietary strategies in young weaned calves.

Feeding diets varying in forage proportion and particle length to lactating dairy cows: II. Effects on duodenal flows and intestinal digestibility of amino acids

A study was conducted to evaluate the effects of forage-to-concentrate (F:C) ratio and forage particle length (FPL) on intake, duodenal flow, and digestibility of individual AA in the intestine of lactating dairy cows. The experiment was designed as a 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments using 4 lactating dairy cows (parity 2) with ruminal and duodenal cannulas. Low (35:65) and high (60:40) F:C ratios (dry matter basis) were combined with 2 FPL of alfalfa silage (short vs. long; 7.9 vs. 19.1 mm). Few interactions between F:C and FPL for duodenal flow and intestinal digestibility of AA occurred, but interactions were detected for intakes of several AA. Intake of essential AA and nonessential AA decreased with increasing F:C, and the intake of several individual AA increased or decreased with increasing FPL. Increasing F:C decreased duodenal flows of essential AA, nonessential AA, and microbial AA due to consistent decreased flows of most individual AA (except Glu). Degradability of most individual AA in the rumen was not affected by F:C ratio or FPL except that the degradability of His was greater with high than low F:C diets, and the degradability of Ser was greater with long versus short FPL diets. However, the degradability of individual AA within diet varied considerably. Overall, F:C ratio and FPL did not affect intestinal digestibility of AA and rumen undegradable protein AA, whereas the digestibility of individual AA in the intestine varied considerably regardless of dietary treatment. These results indicate that increasing F:C ratio decreased AA supply due to decreased flow of AA to the duodenum but altering FPL did not affect AA supply. The results also revealed the necessity to consider both the flows and digestibility of individual AA when optimizing ration formulation to meet AA requirements of dairy cows.

The relationships of dairy ruminal odd- and branched- chain fatty acids to the duodenal bacterial nitrogen flow and volatile fatty acids

The objectives of the present research were to investigate the changes in duodenal bacterial nitrogen flow and volatile fatty acids (VFAs) with the different dietary ratios of forage and concentrate (F:C) and to determine the relationship of duodenal bacterial nitrogen flow and volatile fatty acids with ruminal odd- and branched-chain fatty acids (OBCFAs). The experimental design was a 3 × 3 Latin square. Three rumen- and duodenal-fistulated dry Holstein cows were fed three rations with different dietary ratios of forage and concentrate (F:C; 30:70, 50:50 and 70:30). The rumen and duodenal samples were collected every two hours over 3 consecutive days of each sampling period. The determined parameters included OBCFA profiles in the rumen, duodenal bacterial nitrogen flow, VFAs, ammonia nitrogen (NH3-N) content and pH. The results showed that ruminal OBCFA contents, duodenal bacterial nitrogen flow, VFAs, ammonia nitrogen (NH3-N) and pH were significantly influenced by the different dietary F:C ratios and sampling times (P < 0.01). The ruminal contents of C15:0 and C15:0 + C17:0 were positively related to the molar proportions of duodenal acetate but negatively correlated with the propionate, butyrate and NH3-N contents (P < 0.05). The ruminal C15:0/C17:0 ratio was positively correlated with the proportions of acetate and pH (P < 0.05) but negatively correlated with VFA contents in the duodenum (P < 0.05). The duodenal bacterial nitrogen flow was positively correlated with ruminal C11:0 and isoC17:0 contents (P < 0.05) but negatively correlated with C15:0/C17:0 and isoC15:0/isoC17:0 (P < 0.05). These findings suggested that some ruminal OBCFAs are closely related to the microbial nitrogen and volatile fatty acids in duodenal flow and significantly changed with the proportion of forage in diets. Ruminal OBCFA have the potential to predict microbial nitrogen flow, and the predicted equations for duodenal microbial nitrogen flow were established with OBCFAs in the rumen.

Effects of increasing amounts of extruded linseed in the diet on apparent ruminal synthesis of some B vitamins in dairy cows

Many studies have shown that metabolic efficiency of ruminants can be significantly decreased when B-vitamin supply is insufficient. Under the present state of knowledge, the amounts of B vitamins available for intestinal absorption cannot be predicted based on diet composition. Therefore, in an attempt to increase our understanding of the effects of dietary factors, on B-vitamin supply for dairy cows, the effects of increasing amounts of extruded linseed in diets based on hay (permanent grassland hay, H; Experiment 1) or corn silage (CS; Experiment 2) on apparent ruminal synthesis (ARS) of thiamin, riboflavin, niacin, vitamin B6, folates and vitamin B12 were evaluated. In each experiment, four lactating Holstein cows fitted with cannulas in the rumen and the proximal duodenum were used in a 4 × 4 Latin square design. In both experiments, the dietary treatments consisted of an increasing supply of extruded linseed representing 0%, 5%, 10% or 15% of diet DM. The forage : concentrate ratios were 50 : 50 and 60 : 40 for Experiments 1 and 2, respectively. Duodenal flow was determined using YbCl3 as a marker. The ARS of each B vitamin was calculated as duodenal flow – daily intake. In both experiments, treatments did not affect thiamin, riboflavin, niacin and vitamin B12 duodenal flow or ARS. Increasing the dietary concentration of extruded linseed decreased folate intake in Experiment 1 and vitamin B6 intake in Experiment 2 but resulted in a greater duodenal flow of vitamin B6 and folates regardless of the forage used in basal diet. Greater dietary linseed concentrations decreased vitamin B6 apparent degradation in the rumen in CS-based diet only and increased folate ARS in both H- and CS-based diets. Increasing linseed concentration of isonitrogenous and isoenergetic diets increased vitamin B6 and folate supply to dairy cows, both with H- and CS-based diets.

Reducing protein content in the diet of growing goats: implications for nitrogen balance, intestinal nutrient digestion and absorption, and rumen microbiota

Reducing dietary CP content is an effective approach to reduce animal nitrogen excretion and save protein feed resources. However, it is not clear how reducing dietary CP content affects the nutrient digestion and absorption in the gut of ruminants, therefore it is difficult to accurately determine how much reduction in dietary CP content is appropriate. This study was conducted to investigate the effects of reduced dietary CP content on N balance, intestinal nutrient digestion and absorption, and rumen microbiota in growing goats. To determine N balance, 18 growing wether goats (25.0 ± 0.5 kg) were randomly assigned to one of three diets: 13.0% (control), 11.5% and 10.0% CP. Another 18 growing wether goats (25.0 ± 0.5 kg) were surgically fitted with ruminal, proximate duodenal, and terminal ileal fistulae and were randomly assigned to one of the three diets to investigate intestinal amino acid (AA) absorption and rumen microbiota. The results showed that fecal and urinary N excretion of goats fed diets containing 11.5% and 10.0% CP were lower than those of goats fed the control diet (P < 0.05). When compared with goats fed the control diet, N retention was decreased and apparent N digestibility in the entire gastrointestinal tract was increased in goats fed the 10% CP diet (P < 0.05). When compared with goats fed the control diet, the duodenal flow of lysine, tryptophan and phenylalanine was decreased in goats fed the 11.5% CP diet (P < 0.05) and that of lysine, methionine, tryptophan, phenylalanine, leucine, glutamic acid, tyrosine, essential AAs (EAAs) and total AAs (TAAs) was decreased in goats fed the 10.0% CP diet (P < 0.05). When compared with goats fed the control diet, the apparent absorption of TAAs in the small intestine was increased in goats fed the 11.5% CP diet (P < 0.05) and that of isoleucine, serine, cysteine, EAAs, non-essential AAs, and TAAs in the small intestine was increased in goats fed the 10.0% CP diet (P < 0.05). When compared with goats fed the control diet, the relative richness of Bacteroidetes and Fibrobacteres was increased and that of Proteobacteria and Synergistetes was decreased in the rumen of goats fed a diet with 10.0% CP. In conclusion, reducing dietary CP content reduced N excretion and increased nutrient utilization by improving rumen fermentation, enhancing nutrient digestion and absorption, and altering rumen microbiota in growing goats.

Effects of toasting and decortication of oat on nutrient digestibility in the rumen and small intestine and on amino acid supply in dairy cows

This study examined the potential for decorticating and toasting of oat (Avena sativa) to supply crude protein (CP) and amino acids (AA) in dairy cows. Four lactating Danish Holstein Friesian cows fitted with ruminal, duodenal, and ileal cannulas were assigned to a 4 × 4 Latin square design. Cows were fed experimental diets ad libitum based on grass-clover silage and toasted fava beans, with oat included in different forms arranged in a 2 × 2 factorial: whole oat, decorticated oat, toasted oat, and decorticated toasted oat. In situ rumen degradability of processed oat was also evaluated. Decortication increased starch intake by 0.38 kg/d and reduced NDF intake by 0.91 kg/d. Toasting reduced ruminal AA digestibility and increased duodenal flow of CP by 0.41 kg/d. In situ degradation rate and effective degradability of CP in the rumen were reduced by 0.46 h-1 and 310 g/kg CP due to toasting. Both decortication and toasting increased microbial synthesis of CP by 0.20 and 0.41 kg/d, respectively. Decortication and toasting did not affect small intestinal AA digestibility, but did increase the total digested amount of AA by 154 and 250 g/d, respectively. Milk production was not affected by treatments. Methane production (L/d) decreased with decortication and toasting. In conclusion, unless an interaction exists between decortication and toasting, the results indicate additive effects of toasting and decorticating oat for increasing the supply of digestible AA to the small intestine of dairy cows.

Enteric methane emission and digestion in dairy cows fed wheat or molasses

The aim of this experiment was to measure enteric methane (CH4) emission and its relation with rumen digestion in dairy cows fed diets rich in 1 of the 2 carbohydrate sources, starch or sugar. The rations were based on late first-cut grass-clover silage supplemented with wheat (Wh), NaOH-treated wheat (Wh+NaOH), sugar beet molasses (Mo), or sugar beet molasses with addition of sodium bicarbonate (Mo+Bic). Wheat and molasses made up 35% of dry matter in the 2 diets with molasses and wheat, respectively. Four cows fitted with ruminal, duodenal, and ileal canulae were used in a 4 × 4 Latin square design. Nutrient digestibility was measured using chromium oxide and titanium oxide as flow markers, and emissions of CH4 and hydrogen were measured via open-circuit indirect calorimetry on 4 consecutive days. Data were analyzed using PROC MIXED of SAS (version 9.4; SAS Institute Inc., Cary, NC) with treatment and period as fixed effects and cow as random effect. Furthermore, orthogonal contrasts were calculated. The cows produced 32.5, 33.6, 36.2, and 35.1 L of CH4/kg of dry matter intake (DMI) on diets Wh, Wh+NaOH, Mo, and Mo+Bic, respectively. The emission of CH4 per day, per kilogram of DMI, and per kilogram of energy-corrected milk as well as daily hydrogen emission were higher on the Mo diet compared with the Wh diet. With the present inclusion of wheat and molasses in the diet, no effects of NaOH treatment of wheat or of sodium bicarbonate supplementation to the Mo diet could be demonstrated on CH4 emission expressed per kilogram of DMI or per kilogram of energy-corrected milk. The duodenal flow of starch was higher when wheat was treated with NaOH. Under the conditions in the present experiment, ruminal NDF digestibility was not affected by carbohydrate source, NaOH treatment of wheat, or bicarbonate supplementation. Total volatile fatty acid concentration in the rumen and the proportions of acetate and propionate were not affected by carbohydrate source, NaOH treatment of wheat, or bicarbonate supplementation. Likewise, we could not show any influence of diet on microbial protein synthesis or efficiency of microbial protein synthesis expressed as grams of microbial protein synthesis per kilogram of true rumen-digested organic matter. We concluded that CH4 emission was increased when wheat was replaced by molasses, whereas no effect of manipulating rumen fermentation by NaOH treatment of wheat or addition of bicarbonate to molasses could be found with a level of approximately 25% of dry matter from starch and sugar, respectively.

Influences of urea fermentation potential on growth performance, dietary energetics, digestive function, and blood urea N in Holstein steers fed a finishing diet based on steam-flaked corn where metabolizable protein supply was otherwise in excess of theoretical requirement

ABSTRACT Objectives This study was conducted to examine the effect of urea fermentation potential (UFP) on digestive function, BUN, growth performance, and dietary energetics, in steers fed a finishing diet based on steam-flaked corn containing 15% dried distillers grains with solubles. Materials and Methods Four UFP levels were evaluated (−0.30, 0.10, 0.50, 0.90). The UFP levels were manipulated by dietary urea inclusion level of 1.20, 0.80, 0.40 and 0%, respectively (DM basis). Results and Discussion Dietary UFP did not affect (P > 0.10) ruminal digestion of feed N. Ruminal starch digestion decreased with increasing UFP (linear effect, P = 0.02). Ruminal digestion of starch and OM tended to be maximal (quadratic effect, P ≤ 0.07) at dietary UFP of 0.1%. Increasing UFP decreased flow to duodenum of nonammonia-N (linear effect, P = 0.04), and microbial N (linear effect, P = 0.05). Duodenal flow of feed N was not affected (P = 0.18) by dietary UFP. Increasing dietary UFP decreased total-tract digestion of OM (linear effect, P = 0.02), starch (linear effect, P = 0.03), and digestible energy (linear effect, P = 0.03). Increasing dietary UFP decreased ruminal pH (linear effect, P = 0.01) 1 h after feeding. Thereafter, the influence of dietary UFP on ruminal pH was not appreciable. Increasing dietary UFP decreased ruminal ammonia-N 1 h after feeding (linear effect, P Implications and Applications Even when finishing diet formulations otherwise exceed MP requirements, dietary UFP level remains a relevant factor to optimize dietary energy use. Dietary UFP levels greater than 0.50% could negatively affect digestion, gain efficiency, and dietary NE use.

Effects of the supplementation of distillers’ grape residues on ruminal degradability, whole tract digestibility and nitrogen metabolism in sheep

ABSTRACTFive ruminally and duodenally cannulated Kazakh male lambs (30 ± 2.75 kg) maintained singly in a metabolic cage were used in a 5 × 5 Latin square experiment to investigate the effect of supplementing a ration with five different levels of distillers’ grape residue (DGR) on ruminal degradability, whole tract digestibility and nitrogen (N) metabolism of growing lambs. The rations were isoenergetic and isonitrogenous and contained 0, 3.85, 7.70, 11.55 and 15.41% DGR (DM basis). Each experimental period lasted for 18 d: 10 d for adaptation to the dietary treatment and 8 d for faecal, urinary, ruminal and duodenal digesta sample collections. The outflow rate of ruminal digesta increased (p = 0.032) linearly with the increased level of dietary neutral detergent fibre content, caused by the supplementation of DGR. As a result, the effective degradability of dry matter and crude protein decreased significantly with the treatments. Although the dietary intake of N, duodenal flow of total N, and the endogenous N at the duodenum were not affected by experimental treatments, N fractions in the digesta were altered. Ruminal microbial N decreased (p < 0.01) linearly; in contrast, ruminal un-degradable protein increased linearly (p < 0.01) in response to the increased addition of DGR. Although there was no significant difference in faecal N among treatments, N retention was increased linearly (p = 0.014), owing to the remarkable reduction (p = 0.016) of urinary N excretion with an increasing level of DGR. The results indicate that the DGR has some potential benefits of increasing the supply of bypass protein and of improving the utilisation efficiency of N for sheep. Therefore, the supplementation of DGR in ruminant feeding is recommended at levels not exceeding 10% of the diet.

Bypassing Major Venous Occlusion and Duodenal Lesions in Rats, and Therapy with the Stable Gastric Pentadecapeptide BPC 157, L‐NAME and L‐arginine

BackgroundUp to now, application of, prototype cytoprotective agent BPC 157 induced bypassing of occlusion, in rats underwent vessels occlusions, through rapid collaterals presentation.AimsTo show that duodenal lesions induced by major venous occlusion can be attenuated by BPC 157, prototype cytoprotective agent, regardless NO system involvement.MethodsIn rats underwent superior anterior pancreaticoduodenal vein (SPDAV)‐ligation, medication was bath at the ligated SAPDV (BPC 157 10 ug, 10 ng/kg/1ml bath/rat; L‐NAME 5 mg/kg/1ml bath/rat; L‐arginine 100 mg/kg/1ml bath/rat, alone and/or together; or BPC 157 10 ug/kg instilled into rat stomach, at 1 min ligation‐time.ResultsUnlike severe course in controls, after BPC 157 application, rats commonly exhibited strong attenuation of mucosal lesion and serosal congestion, improved vessels presentation, much more interconnections, branching raised more than 60% from the initial value; inferior anterior pancreaticoduodenal vein (IAPDV) and superior mesenteric vein (SMV) were both non congested. Interestingly, while at 5 min and 30 min period alone L‐NAME and L‐arginine decreased mucosal and serosal duodenal lesions, their effect was worsening at 24 h period, no effect on the vessels collaterals and branching. Together, L‐NAME+L‐arginine antagonized each other response at any point, and thus, NO‐related effect. With BPC 157 all SAPDV‐ligated rats receiving L‐NAME and/or L‐arginine appear like rats treated with BPC 157 alone.ConclusionsBPC 157, rapidly bypassing occlusion, rescued original duodenal flow through IAPDV to SMV flow, NO‐system related effect.Support or Funding InformationThis work was supported by the Ministry of Science, Education and Sports, Republic of Croatia [grant number 108‐1083570‐3635].This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.