Ruminal Organic Matter Digestion Research Articles

Influence of Feeding Level on Digestion and Protein Passage to the Duodenum in Cows Fed High Concentrate Diets

Abstract Dairy cows equipped with rumen and duodenal T-piece cannulae were given 7 diets each fed at two feeding levels, viz. approximately 7 and 14 kg DM per day, equivalent to 1.2 to 1.5 and 2.4 to 3.0 times energy maintenance requirement respectively. The diets consisted of app. 25% barley straw plus concentrates. The concentrates were soybean meal, beet-pulp-molasses, cottonseed cakes, fish meal and grass pellets with 18 or 12% protein. Cromic oxide and polyethylene glycol were given as indigestible markers. Twelve rumen, duodenal and faecal samples were taken to represent a 24-hour period. As a mean for the 7 diets, level of feed intake did not significantly influence neither the passage to the duodenum of non-ammonia-N (NAN) or amino acid-N (AAN) per kg dry matter intake, nor the calculated feed protein degradability in the rumen. Doubling of the feeding level resulted in a significant change in rumen pH from 6.59 to 6.47, in the digestibility of organic matter in the rumen from 37.1% to 39.8% and in the passage of starch + sugar to the duodenum from 11.8 g to 15.4 g per kg dry matter intake. The digestibility of crude fibre in the rumen, and the total digestibility of crude fibre and organic matter was as a mean unaffected by feeding level. Significant interactions between diet and feeding level were found for the passage of NAN and AAN to the duodenum, the calculated degradability of feed protein, the ruminal digestion of organic matter and crude fibre and the total digestion of crude fibre as well as for the passage of starch + sugar to the duodenum per kg dry matter intake.

Effects of Sarsaponin on Digestion and Passage Rates in Cattle Fed Medium to Low Concentrate1,2

Four dairy cows with duodenal cannulae were fed diets consisting of sorghum silage (67% of dietary dry matter) at 85% of ad libitum intake with 0 (control diet) or 44ppm (dry matter) sarsaponin (sarsaponin diet) in a crossover experiment. Digestion coefficients for organic matter were low but increased by addition of sarsaponin both in the rumen (43.7 versus 32.4%) and total tract (52.1 versus 48.2%). Digestibilities of starch and nitrogen in the rumen and total tract and passage rates of fluid, concentrate, and silage tended to be greater for the sarsaponin diet. Extent of ruminal digestion of organic matter was related to passage rate of concentrate (correlation .81) and fluid (correlation .75). In a second study, diets contained 50% concentrate either with or without sarsaponin added at 44ppm. Ruminal pH for animals given sarsaponin tended to be lower 4, 8, and 12h after feeding. In situ rate constants of dry matter disappearance tended to be greater with the control diet for corn, alfalfa, and prairie hay and lower for milo and soybean meal. Lag time of digestion tended to be longer with the sarsaponin diet for corn, milo, soybean meal, and corn gluten meal but shorter for alfalfa and prairie hay. Although sarsaponin may increase ruminal digestion of medium to low concentrate diets, in situ data indicate that effects may differ with type of feed.

EFFECT OF FORAGE AMOUNT AND PARTICLE SIZE IN DIETS OF LACTATING DAIRY COWS ON SITE OF DIGESTION AND MICROBIAL PROTEIN SYNTHESIS

Lactating Holstein cows fitted with ruminal and duodenal T-type cannulae were used in two studies to determine the effect of forage: concentrate ratio and forage particle size on site of nutrient digestion and microbial protein synthesis. In exp. 1, cows were fed alfalfa hay at 24, 38, 58 and 80% of total dry matter intake. Organic matter (OM) digestion in the total tract (OMD) increased with increasing concentrate level but apparent ruminal OM digestion (AROMD) was unaffected by diet. Digestion of acid detergent fiber (ADF) was similar among the higher forage diets, but was depressed at the 24% forage level. Efficiency of microbial protein synthesis (MPS) was depressed by high concentrate diets and was positively correlated (P < 0.05) to turnover rate within the rumen. In exp. 2, cows were fed 20% concentrate and 80% alfalfa hay in long, chopped or ground and pelleted form. AROMD was lower with ground hay but OMD was unaffected by diet. Digestibility of ADF in the rumen was lower with ground hay, but was partially compensated for by increased hindgut digestion of ADF. Flow of feed plus endogenous nitrogen (N) at the duodenum was 37% and 47% on N intake with long and ground hay, respectively. Efficiency of MPS increased 15% and postruminal N digestion increased 36% when ground hay replaced long hay. Efficiency of MPS was directly related to ruminal solids turnover rate and inversely related to liquid dilution rate. These results demonstrate improvements in efficiency of MPS with either increasing amounts of forage in the diet or increased ruminal passage of solids. Key words: Digestion, microbial protein, rate of passage, cattle, rumen forage

Influence of Nonprotein Nitrogen and Protein of Low Rumen Degradability on Nitrogen Flow and Utilization in Lactating Dairy Cows

Four lactating cows, each fitted with a rumen cannula and duodenal and ileal t-cannulae, were used to measure flow and digestion of nitrogenous compounds in the digestive tract. Dietary dry matter contained 17% crude protein and 50:50 forage: concentrate. Treatments were: 1) corn silage-soybean meal; 2) corn silage-heated soybean meal; 3) ammonia-treated corn silage-soybean meal; and 4) ammonia-treated corn silage-heated soybean meal. Flow of organic matter to the duodenum was overestimated when lanthanum or chromium ethylene-diaminetetraacetate was used as an indigestible marker. This resulted in low estimates of ruminal digestion of organic matter and high estimates of nitrogen flow to the duodenum. However, calculations using lanthanum or lignin as markers yielded similar organic matter flow to ileum and feces.With acid-detergent lignin as a marker, estimates of dietary nitrogen degraded in the rumen were: corn silage-heated soybean meal, 55.0%; ammonia-treated corn silage-heated soybean meal, 58.8%; ammonia-treated corn silage-soybean meal, 63.3%; and corn silage-soybean meal, 66.0%. Digestion in the small intestine of nonammonia nitrogen was equal for all treatments suggesting that availability of heated soybean meal in the intestine was not different, although ruminal degradability tended to be lower. Feeding diets containing nonprotein nitrogen did not decrease available nitrogen at the duodenum.

Simultaneous diffusion and reaction of azide in a cylindrical crystal of ferrimyoglobin

The aim of this study was to compare effects of dietary inclusion of hazelnut meal (HZM) with soybean meal (SBM) on site of digestion and microbial protein synthesis in sheep. Four ruminally and duodenally cannulated female Redkaraman × kıvırcık sheep (initial BW of 44.0 ± 1.02 kg) were utilized in a crossover experiment. Sheep were fed a diet of 60% corn silage (DM basis) and 40% concentrate consisting of barley and SBM or HZM. Feed was fed at 115% of ad libitum intake. Intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were similar between sheep fed SBM or HZM based diets (P > 0.05). Organic matter intake averaged 1089 (2.37% BW) and 1143 g/day (2.42% BW) for SBM and HZM, respectively. Apparent and true ruminal and total tract DM and OM digestibilities did not differ between diets (P > 0.05). True ruminal OM digestibility was 74.3 and 74.6% for SBM and HZM based diets, respectively. Total CP entering the duodenum was similar between diets (P > 0.05). Dietary plus endogenous CP entering the duodenum in grams and as a percentage of total CP was greater (P < 0.05) for SBM versus HZM. Quantities of microbial protein (P < 0.15) and NH3 N (P < 0.08) flowing to the duodenum tended to be less for SBM versus HZM; percentages of total CP were lower (P < 0.05) for SBM. Apparent ruminal and total tract CP digestibilities did not differ between diets, but true ruminal CP digestibility and efficiency of microbial protein synthesis tended to be higher in animals fed the HZM based diet compared with the diet based on SBM (P < 0.13). In conclusion, because total CP entering duodenum did not differ between diets, HZM can be substituted for SBM in sheep fed corn silage and barley based diets with a moderate CP level.