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1.
Effects of extent of barley rolling on chewing activities, ruminal fermentation, and site and extent of digestion were evaluated for feedlot finishing cattle diets in a 4 x 4 Latin square design. Four Jersey steers (452 kg), cannulated in the rumen and duodenum, were used. Barley grain was temper-rolled to four extents: coarse, medium, medium-flat, and flat, which were expressed as processing index (PI, volume weight of barley after processing expressed as a percentage of its volume weight before processing, DM basis) and equivalent to 82, 75, 70, and 65%, respectively. Diets consisted of 9.7% barley silage, 86% temper-rolled barley, and 4.3% other ingredients (DM basis). Steers were offered ad libitum access to a total mixed ration once daily. Dry matter intake was not affected (P > 0.15) by PI of barley. Digestibility of OM in the rumen and in the total tract were numerically lower (P = 0.13) for steers fed coarsely rolled barley than for steers fed more extensively processed barley. Digestibility of starch in the total tract was linearly increased (P = 0.02) with grain processing, but NDF digestion was not affected by processing (P > 0.15). Digestibility of CP did not differ in the rumen but tended (P = 0.08) to increase in the total tract with increased processing of barley. Flow of microbial nitrogen to the duodenum was approximately one-third lower (linear effect, P = 0.06) for steers fed coarsely rolled barley than for steers fed further rolled barley. Increased grain processing tended to decrease (linear effect, P = 0.08) rumination time without affecting eating time. These results indicate that optimal degree of rolling for barley fed to feedlot cattle corresponded to a PI of 75% or lower. Coarsely rolled barley is not recommended because it resulted in the lowest digestibility and lowest microbial protein synthesis. Processing barley to attain a PI less than 75% resulted in marginal improvements in feed digestion, but rumination time decreased, which could lead to problems associated with acidosis if lower-fiber diets are used.  相似文献   

2.
Two finishing trials, one laboratory trial and one metabolism trial were conducted with the following objectives: 1) to determine the associative effects of feeding high-moisture corn (HMC) with either dry-rolled grain sorghum (DRGS) or dry-rolled corn (DRC) and 2) to evaluate HMC when harvested at different moisture levels, stored in different structures, or fed as whole or rolled HMC. In Trial 1, yearling steers (BW, 328 kg) were fed diets containing mixtures of HMC and DRGS. As level (0, 33, 100%, as percentage of grain DM) of DRGS increased, ADG (P less than .03) and gain/feed (P less than .001) decreased linearly; gain/feed tended to be affected quadratically (P = .14). In Trial 2, yearling steers (BW, 382 kg) fed HMC, stored whole in an upright, oxygen-limiting silo and rolled coarsely before feeding, gained faster (1.46 vs 1.36 kg/d) and more efficiently (.142 vs. .131 gain/feed) than steers fed whole HMC (P less than .01). In Trial 3, as length of storage of bunker HMC increased, in vitro rate of starch digestion and soluble N content increased (20.4 and 36.8%, respectively) and grain pH decreased (10.9%). In Trial 4, steers fed HMC or a mixture of 75% HMC with 25% DRGS had similar ruminal pH throughout a grain adaptation period, but total ruminal VFA were greater (P less than .005) for steers fed HMC alone. These data are interpreted to suggest that feeding a mixture of HMC, ground and stored in a bunker or silo bag, with DRGS will result in a 3.2% associative effect. However, no associative effects were measured when a mixture of HMC, stored whole and fed whole or rolled, and DRC were fed.  相似文献   

3.
Three experiments were conducted to determine the effects of cattle age and dietary forage level on the utilization of corn fed whole or ground to feedlot cattle. In Exp. 1, 16 steers were used to investigate the effects of cattle age and corn processing on diet digestibility. Two cattle age categories were evaluated (weanling [254 +/- 20 kg BW] and yearling [477 +/- 29 kg BW]; eight steers per group), and corn was fed either ground or whole to each cattle age category. Cattle age and corn processing did not affect (P > 0.10) diet digestibility of DM, OM, starch, CP, NDF or ADF, and no interactions (P > 0.10) between these two factors were detected. In Exp. 2, the effects of forage level and corn processing on feedlot performance and carcass characteristics were evaluated. One hundred eighty steers (310 +/- 40 kg BW) were allotted to 24 pens, and were fed one of the following diets: high-forage (18.2% corn silage) cracked corn (HFCC); high-forage shifting corn (whole corn for the first half of the trial, then cracked corn until harvest; HFSC); high-forage whole corn (HFWC); low-forage (5.2% corn silage) cracked corn (LFCC); low-forage shifting corn (LFSC); and low-forage whole corn (LFWC). For the high-forage diets, steers fed cracked corn had 7% greater DMI than those fed whole corn, whereas for the low-forage diets, grain processing did not affect DMI (interaction; P = 0.02). No interactions (P > 0.10) between forage level and corn processing were found for ADG and G:F. Total trial ADG and G:F, and percentage of carcasses grading USDA Choice, and carcass yield grade were not affected (P > 0.10) by corn processing. Cattle with fewer days on feed grew faster and more efficiently when cracked corn was fed, whereas cattle with longer days on feed had greater ADG and G:F when corn was fed whole (interaction; P < 0.10). In Exp. 3, the effects of forage level and corn processing on diet digestibility were evaluated. The high-forage cracked corn, high-forage whole corn, low-forage cracked corn, and low-forage whole corn diets used in Exp. 2 were fed to 16 steers (350 +/- 27 kg BW) in a digestion trial. No interactions (P > 0.10) between forage level and corn processing were detected for starch digestibility. Forage level and corn processing (grinding) did not affect (P > 0.10) diet DM, OM, starch, CP, and NDF digestibility. Processing corn did not provide additional benefits to feedlot cattle performance under these experimental conditions.  相似文献   

4.
Six cannulated Salers steers (305 +/- 17 kg initial BW) were used in a double 3 x 3 Latin square design to compare the effects of the nature of the cereal (wheat vs corn) and the corn genotype (dent vs flint) on rate, site, and extent of digestion of high-concentrate diets. The cereals were coarsely cracked, and the diets were balanced to have the same percentage of starch (47.7 +/- 2.3%) and CP (14.6 +/- .7%). Differences in ruminal starch digestion were observed between wheat- and corn-based diets (86.6 vs 47.8%; P < .001) and between corn genotypes (60.8 vs 34.8% for dent and flint corns; P < .001). For flint corn, more than half the starch was digested in the hindgut. Total tract digestion of starch was greater (P < .001) by steers fed wheat than by those fed corn and did not differ (P > .1) between the two corn genotypes. Ruminal mean pH (P < .01) was lower and total VFA concentration (P < .1) was higher for wheat- than for corn-based diets. Ruminal acetate:propionate tended to increase with the decrease in the amount of starch degraded in the rumen, but differences were not significant (P > .1). When wheat replaced corn, nonammonia, nonmicrobial N duodenal flow decreased (P < .01), and microbial duodenal flow increased (P < .05), so there were no differences in the duodenal flow of nonammonia N duodenal flow (P > .1). The lower nonammonia N duodenal flow for the dent corn- than for the flint corn-based diet (P < .05) was related to a lower passage of nonammonia, nonmicrobial N into the duodenum. Efficiency of microbial protein synthesis was inversely correlated with the amount of starch degraded in the rumen. Nature of the cereal, wheat vs corn, and genotype of the corn, dent vs flint, alter the site and extent of starch digestion.  相似文献   

5.
Two trials were conducted to determine the effect of corn processing method on performance and carcass traits in steers fed finishing diets containing wet corn gluten feed (WCGF). In Trial 1, 480 steer calves (303 kg initial BW) were fed eight finishing diets: 1) dry-rolled corn (DRC) without; and 2) with 32% (DM basis) WCGF; 3) steam-flaked corn (SFC) without; and 4) with WCGF; 5) a combination of DRC and SFC without WCGF; 6) finely-ground corn (FGC) with WCGF; 7) high-moisture corn (HMC) with WCGF; and 8) whole corn (WC) with WCGF. Feeding WC + WCGF increased (P < 0.10) DMI and decreased gain:feed compared with all other treatments. Feeding DRC + WCGF increased (P < 0.10) DMI and decreased (P < 0.10) gain:feed compared with treatments other than WC + WCGF. Steers on treatments that included WCGF gained similarly, regardless of corn processing method, and at a rate 6% faster (P < 0.10) than steers fed diets that did not include WCGF. Gain:feed did not differ among steers fed SFC, SFC + WCGF, SFC + DRC, and HMC + WCGF. Steers fed SFC or SFC + WCGF were more efficient (P < 0.10) than steers fed DRC or FGC + WCGF. In Trial 2, 288 steer calves (382 kg initial BW) were fed six finishing diets: 1) DRC without; and 2) with 22% (DM basis) WCGF; 3) SFC without; and 4) with WCGF; 5) finely rolled corn (FRC) with WCGF; and 6) HMC corn with WCGF. Steers fed DRC + WCGF or FRC + WCGF consumed more DM (P < 0.10) than steers fed DRC, SFC, or SFC + WCGF. Feed intake did not differ between steers fed SFC + WCGF and HMC + WCGF. All treatment groups receiving WCGF consumed more DM (P < 0.10) feed than steers fed DRC or SFC without WCGF. Steers fed SFC + WCGF gained 8% faster (P < 0.10), and steers fed DRC 9.5% slower (P < 0.10) than steers receiving all other treatments. Daily gains did not differ among other treatment groups. Steers fed SFC or SFC + WCGF gained 10% more (P < 0.10) efficiently than all other treatment groups. Feed efficiency did not differ among steers fed DRC, DRC + WCGF, FRC + WCGF, and HMC + WCGF. Estimates for the NEg of WCGF calculated from animal performance indicated that WCGF contained approximately 25.3% more energy when fed with SFC than when fed with DRC. In general, more intensively processing corn improved gain:feed in finishing diets containing WCGF.  相似文献   

6.
Two experiments were conducted to evaluate combinations of wet corn gluten feed (WCGF) and barley, as well as the particle size of dry-rolled barley and corn, in finishing steer diets containing WCGF. In Exp. 1, 144 crossbred steers (initial BW = 298.9 +/- 1.4 kg) were used to evaluate barley (0.566 kg/L and 23.5% NDF for whole barley) and WCGF combinations in finishing diets containing 0, 17, 35, 52, or 69% WCGF (DM basis), replacing barley and concentrated separator byproduct. A sixth treatment consisted of corn (0.726 kg/L and 11.1% NDF for whole corn), replacing barley in the 35% WCGF treatment. In Exp. 2, 144 crossbred steers (initial BW = 315.0 +/- 1.5 kg) were used to evaluate coarse or fine, dry-rolled barley or corn (0.632 and 0.699 kg/L; 26.6 and 15.9% NDF for whole barley and corn, respectively) in finishing diets containing WCGF. A factorial treatment design was used; the factors were grain source (corn or barley) and degree of processing (coarse or fine). The diets contained 50% WCGF, 42% grain (corn or barley), 5% alfalfa hay, and 3% supplement (DM basis). In Exp. 1, DMI and ADG responded quadratically (P < or = 0.03), peaking at 35 and 52% WCGF, respectively. The efficiency of gain was not affected (P > or = 0.42) by dietary treatment. Steers fed dry-rolled corn and 35% WCGF had heavier HCW, lower DMI, greater ADG, increased G:F, increased s.c. fat thickness at the 12th rib, and greater yield grades compared with steers fed dry-rolled barley and 35% WCGF (P < or = 0.04). The apparent dietary NEg was similar among the barley and WCGF combinations (P > or = 0.51); however, the corn and 35% WCGF diet was 25% more energy dense (P < 0.001) than was the barley and 35% WCGF diet. In Exp. 2, no grain x processing interactions (P > or = 0.39) were observed. Particle size was 2.15 and 2.59 mm for fine- and coarse-rolled barley and was 1.90 and 3.23 mm for fine- and coarse-rolled corn. Steers fed a combination of corn and WCGF had increased ADG, greater G:F, heavier HCW, larger LM area, more s.c. fat thickness at the 12th rib, greater yield grades, increased marbling, and more KPH compared with steers fed a combination of barley and WCGF (P < or = 0.03). Fine-rolling of the grain increased fat thickness (P = 0.04). The addition of WCGF to the barley-based diets increased DMI and gain. Decreasing grain particle size did not greatly affect performance of the steers fed the 50% WCGF diets; however, carcasses from the steers fed the fine-rolled grain contained more fat.  相似文献   

7.
The effect of supplementation with different levels of cracked corn on the sites of OM, total dietary fiber (TDF), ADF, and starch digestion in steers fed fresh alfalfa indoors was determined. Six Angus steers (338 +/- 19 kg) fitted with cannulas in the rumen, duodenum, and ileum consumed 1) alfalfa (20.4% CP, 41.6% NDF) ad libitum (AALF); 2), 3), and 4) AALF supplemented (S) with .4, .8, or 1.2%, respectively, of BW of corn; or 5) alfalfa restricted at the average level of forage intake of S steers (RALF), in a 5 x 5 Latin square design. Total OM intake was lower (P < .01) in steers fed RALF than in those fed AALF but level of forage intake did not affect sites of OM, TDF, or starch digestion (P > .05). Forage OM intake decreased (P < .01) linearly (8,496 to 5,840 g/d) but total OM intake increased (P = .03) linearly (8,496 to 9,344 g/d) as corn increased from .4 to 1.2% BW. Ruminal apparent and true OM disappearance was not affected, but OM disappearing in the small intestine increased (P < .01) linearly with increasing levels of corn. Total tract OM digestibility (71.2 to 76.2%) and the proportion of OM intake that was digested in the small intestine (15.4 to 24.5%) increased (P < .01) linearly as corn increased. The TDF and ADF intakes decreased (P < .01) linearly as level of corn increased. Total tract TDF and ADF digestibilities were not different among treatments (average 62.9 and 57.8%, respectively). Starch intake and starch digested in the rumen and small and large intestine increased (P < .01) linearly with increasing corn level. Ruminal pH and VFA concentrations decreased and increased (P < .01), respectively, with increasing corn. Supplementation with corn increased OM intake, decreased forage OM intake, and increased the proportion of OM that was digested in the small intestine, but fiber digestion was not affected.  相似文献   

8.
Five Holstein steers (235 kg of BW) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 5 Latin square design experiment to determine the effects of supplemental fat source on site and extent of nutrient digestion and ruminal fermentation. Treatments were diets based on steam-flaked corn containing no supplemental fat (control) or 4% (DM basis) supplemental fat as tallow, dried full-fat corn germ (corn germ), corn oil, or flax oil. Fat supplementation decreased (P < 0.08) ruminal starch digestion but increased (P < 0.03) small intestinal starch digestion as a percentage of intake. Feeding corn germ decreased (P < 0.09) ruminal starch digestion and increased (P < 0.03) large intestinal starch digestion compared with steers fed corn oil. Large intestinal starch digestion was less (P < 0.04), and ruminal NDF digestion was greater (P < 0.09) for steers fed tallow compared with steers fed other fat sources. Small intestinal (P < 0.08) and total tract NDF digestibilities were greater (P < 0.02) for steers fed corn germ than for those fed corn oil. Feeding tallow increased total ruminal VFA (P < 0.03) and NH(3) (P < 0.07) concentrations compared with steers fed the other fat sources. Feeding corn germ led to a greater (P < 0.02) rate of ruminal liquid outflow compared with corn oil. A diet x hour interaction (P < 0.04) occurred for ruminal pH, with steers fed corn oil having the greatest ruminal pH 18 h after feeding, without differences at other time points. Fat supplementation increased (P < 0.09) ruminal concentrations of Fusobacterium necrophorum. Duodenal flow of C18:3n-3 was greater (P < 0.01) for steers fed flax oil compared with those fed corn oil. Feeding corn germ led to less (P < 0.01) ruminal biohydrogenation of fatty acids compared with corn oil. Steers fed tallow had greater small intestinal digestibility of C14:0 (P < 0.02) and C16:1 (P < 0.04) than steers fed the other fat sources. Fat supplementation decreased (P < 0.06) small intestinal digestibility of C18:0. Feeding corn germ decreased (P < 0.10) small intestinal digestibility of C18:1 compared with corn oil. It appears that source of supplemental fat can affect the site and extent of fatty acid and nutrient digestion in steers fed diets based on steam-flaked corn.  相似文献   

9.
Four trials were conducted to determine the effects of adding various levels and types of fat to dry-rolled corn (DRC) finishing diets containing 0 or 7.5% forage. In Trial 1, 88 yearling steers (mean BW = 352 +/- 38 kg) and 176 heifers (mean BW 316 +/- 15 kg) were blocked by sex and weight into four replications. Treatments were 0, 2, 4, or 6% (DM basis) bleachable fancy tallow (BT) fed with 0 or 7.5% (DM basis) forage. Addition of BT to the 7.5% forage diet had no effect on ADG or gain/feed (G/F). However, adding BT to the all-concentrate diet decreased ADG (linear, P < .01) and G/F (linear, P = .08). In Trial 2, 184 yearling steers (mean BW = 347 +/- 21 kg) and 144 heifers (mean BW 322 +/- 8 kg) were blocked by sex and weight into six replications. Fat treatments were 0% fat, 4% BT, or 4% animal-vegetable oil blend (A-V); each fat treatment was fed with 0 or 7.5% forage. Across forage levels, the addition of fat increased (P < .01) ADG and G/F for cattle fed DRC. In Trial 3, 18 crossbred wether lambs (mean BW = 44.4 +/- 2.5 kg) were fed DRC and 7.5% forage and allotted randomly to the same fat treatments fed in Trial 2. Apparent total tract fat digestibility increased (P < .01) with the addition of BT or A-V. In Trial 4, 40 crossbred wethers (mean BW = 25 +/- 4.1 kg) and 16 ewes (mean BW = 23 +/- 2.7 kg) were individually fed 7.5% forage diets containing 0, 1, 2, or 4% BT. Addition of BT increased (linear, P = .10) G/F. In summary, fat addition to DRC finishing diets fed to yearling cattle did not consistently affect gain/feed, feed intake, and ADG.  相似文献   

10.
Effects of the extent of grain processing and the percentage of silage in barley-based feedlot diets on microbial protein synthesis and nutrient digestibility were evaluated using four steers (initial BW of 442 +/- 15 kg) with ruminal and duodenal cannulas. The experiment was a 4 x 4 Latin square with four periods of 21 d each. Dietary treatments were arranged as a 2 x 2 factorial with two levels of barley silage (20 and 5% DM basis) and two degrees of barley grain processing (coarsely and flatly steamrolled to a processing index [PI] of 86 and 61%, respectively). The PI was quantified as the volume weight of the barley grain after processing, expressed as a percentage of the volume weight prior to processing. Digest a flow (Yb) and microbial (15N) markers were continuously infused into the rumen for a period of 13 d. Ruminal, duodenal, and fecal samples were collected at various times over the last 6 d of marker infusion. Diurnal ruminal pH was measured for 48 h. Intake of DM averaged 1.8% of BW, and was not different among the dietary treatments (P > 0.10). Ruminal starch digestibility was higher (P < 0.05) for the more extensively processed grain and tended (P < 0.10) to be highest when the more extensively processed grain was combined with 5% barley silage. In contrast, ruminal fiber digestibility for the 5% silage diets was reduced (P < 0.05) when the grain was more extensively processed. There was, however, no effect of grain processing on ruminal OM digestibility (P > 0.10), and hence, no inhibitory effect on microbial N flow to the intestine (P > 0.10). There was also no effect of the level of silage on microbial N flow (P > 0.10), but there was a tendency for improved efficiency of microbial protein synthesis for the 20% silage diets (P = 0.072). Ruminal escape of nonmicrobial N (P = 0.003) was greater, and thus, protein flow to the intestine was greater for the 5% silage diets. Diurnal ruminal pH was lower (P < 0.05) for 11 of the 24 hourly time points in steers fed the 5% silage diets than those fed the 20% silage diets. In conclusion, barley grain rolled to a PI of 86 to 61% and combined with 20 and 5% barley silage had little effect on microbial protein supply. Microbial protein supply was not inhibited when the barley grain was extensively processed (PI of 61%) and the silage was limited to only 5% of the diet DM, but feed intake of steers in this study was lower than would be expected in the feedlot.  相似文献   

11.
Eight cannulated Holstein steers (average BW: 251 kg) were used in 2 simultaneous 4 x 4 Latin squares in a split-plot arrangement to test the effects of processing method [dry-rolled (DR) vs. steam-flaked (SF); main plot] and vitreousness (V, %; subplot) of yellow dent corn (V55, V61, V63, and V65) on site of digestion of diets containing 73.2% corn grain. No vitreousness x processing method interactions were detected for ruminal digestion, but ruminal starch digestion was 14.4% lower (P < 0.01) for DR than for SF corn. Interactions were detected between vitreousness and processing method for postruminal (P < 0.10) and total tract digestion (P < 0.05). With DR, vitreousness tended to decrease (linear effect, P < 0.10) postruminal OM and starch digestion. With SF, vitreousness did not affect (P > or = 0.15) postruminal digestion of OM and starch. Postruminal N digestion tended to decrease (linear effect, P = 0.12) as vitreousness increased. Postruminal digestion was greater for SF than for DR corn OM (25.7%, P < 0.05), starch (94.3%, P < 0.10), and N (10.7%, P < 0.01). Steam flaking increased total tract digestion of OM (11%, P < 0.05), starch (16%, P < 0.01), and N (8.4%, P < 0.05) but decreased total tract ADF digestion (26.7%, P < 0.01). With DR, total tract starch digestion was lower for V65 (cubic effect, P < 0.10) than for the other hybrids. With SF, total tract starch digestion was not affected (P > or = 0.15) by vitreousness. Fecal starch and total tract starch digestion were inversely related (starch digestion, % = 101 - 0.65 x fecal starch, %; r2 = 0.94, P < 0.01). Ruminal pH was greater for steers fed DR than for steers fed SF corn (6.03 vs. 5.62, P < 0.05). Steam flaking decreased (P < 0.01) the ruminal molar proportion of acetate (24%), acetate:propionate molar ratio (55%), estimated methane production (37.5%), and butyrate (11.3%, P < 0.05). There was a vitreousness x processing interaction (P < 0.01) for acetate:propionate. For DR, acetate:propionate tended to increase (linear effect; P < 0.10) with increasing vitreousness. With SF, acetate:propionate was greater (cubic effect, P < 0.01) for V65. Starch from more vitreous corn grain was less digested when corn grain was DR, but this adverse effect of vitreousness on digestion was negated when the corn grain was SF. Of the 19% advantage in energetic efficiency associated with flaked over rolled corn grain, about 3/4 can be attributed to increased OM digestibility, with the remaining 1/4 ascribed to reduced methane loss.  相似文献   

12.
Crossbred steers (n = 7; 400 kg BW), fitted with T-type cannulas in the duodenum and ileum, were used to examine the effects of processing method, dry-rolled (DR) vs. steam-flaked (SF) sorghum grain, and degree of processing (flake density; FD) of SF corn (SFC) and SF sorghum (SFS) grain on site and extent of DM, starch, and N digestibilities and to measure extent of microbial N flow to the duodenum. In Exp. 1, diets contained 77% DRS or 77% SFS with FD of 437, 360, and 283 g/L (SF34, SF28, and SF22). In Exp. 2, diets contained 77% SFC with FD of SF34 or SF22. For sorghum and corn diets, respective average daily intakes were as follows: DM, 6.7 and 8.1 kg; starch, 3.8 and 4.7 kg; N, 136 and 149 g. Steers fed SFS vs. DRS increased (P = .01) starch digestibilities (percentage of intake) in the rumen (82 vs. 67%) and total tract (98.9 vs. 96.5%) and decreased digestibilities in the small intestine (16 vs. 28%; P = .01) and large intestine (.5 vs 1.2%; P = .05). As a percentage of starch entering the segment, digestibility was increased (P = .01) within the small intestine (91 vs. 85%) but was not altered within the large intestine by steers fed SFS vs. DRS. Decreasing FD of SFS and of SFC, respectively, linearly increased starch digestibilities (percentage of intake) in the rumen (P = .03, .02) and total tract (P = .03, .09) and linearly diminished starch digestibilities in the small intestine (P = .04, .09). Starch digestibilities (percentage of entry) within the small or large intestine were not changed by FD. The percentage of dietary corn or sorghum starch digested in the large intestine was very small, less than 2% of intake. Microbial N flow to the duodenum was not altered by SFS compared to DRS, or by decreasing FD of SFS and SFC. Reducing FD of SFS, but not of SFC, tended to decrease (P = .07) microbial efficiency linearly and tended to increase (P = .06) total tract N digestibilities linearly. Steam flaking compared to dry rolling of sorghum grain and decreasing FD of SFC and SFS grain consistently increased starch digestibility in the rumen and total tract of growing steers. The greatest total digestibility of dietary starch occurred when the proportion digested in the rumen was maximized and the fraction digested in the small intestine was minimized. These changes in sites of digestion account, in part, for the improved N conservation and greater hepatic output of glucose by steers fed lower FD of SFS reported in our companion papers.  相似文献   

13.
The value of sunflower seed (SS) in finishing diets was assessed in two feeding trials. In Exp. 1, 60 yearling steers (479 +/- 45 kg) were fed five diets (n = 12). A basal diet (DM basis) of 84.5% steam-rolled barley, 9% barley silage, and 6.5% supplement was fed as is (control), with all the silage replaced (DM basis) with rolled SS, or with grain:silage mix replaced with 9% whole SS, 14% whole SS, or 14% rolled SS. Liver, diaphragm, and brisket samples were obtained from each carcass. In Exp. 2, 120 yearling steers (354 +/- 25 kg) were fed corn- or barley-based diets containing no SS, high-linoleic acid SS, or high-oleic acid SS (a 2 x 3 factorial arrangement, n = 20). Whole SS was included at 10.8% in the corn-based and 14% in the barley-based diets (DM basis). In Exp. 1, feeding whole SS linearly increased DMI (P = 0.02), ADG (P = 0.01), and G:F (P = 0.01). Regression of ME against level of whole SS indicated that SS contained 4.4 to 5.9 Mcal ME/kg. Substituting whole for rolled SS did not significantly alter DMI, ADG, or G:F (8.55 vs. 8.30 kg/d; 1.36 vs. 1.31 kg; and 0.157 vs. 0.158, respectively). Replacing the silage with rolled SS had no effect on DMI (P = 0.91) but marginally enhanced ADG (P = 0.10) and improved G:F (P = 0.01). Dressing percent increased linearly (P = 0.08) with level of SS in the diet. Feeding SS decreased (P < 0.05) levels of 16:0 and 18:3 in both diaphragm and subcutaneous fats, and increased (P = 0.05) the prevalence of 18:1, 18:2, cis-9,trans-11-CLA and trans-10,cis-12-CLA in subcutaneous fat. In Exp. 2, barley diets supplemented with high-linoleic SS decreased DMI (P = 0.02) and ADG (P = 0.007) by steers throughout the trial, whereas no decrease was noted with corn (interaction P = 0.06 for DMI and P = 0.01 for ADG). With barley, high-linoleic SS decreased final live weight (554 vs. 592 kg; P = 0.01), carcass weight (329 vs. 346 kg; P = 0.06), and dressing percent (58.5 vs. 59.4%; P = 0.04). Steers fed high-linoleic SS plus barley had less (P < 0.05) backfat than those fed other SS diets. No adverse effects of SS on liver abscess incidence or meat quality were detected. Although they provide protein and fiber useful in formulating finishing diets for cattle, and did improve performance in Exp. 1, no benefit from substituting SS for grain and roughage was detected in Exp. 2. Because of unexplained inconsistencies between the two experiments, additional research is warranted to confirm the feeding value of SS in diets for feedlot cattle.  相似文献   

14.
Two finishing trials were conducted to determine the effects of adding different types of corn bran, a component of corn gluten feed, on cattle performance. In Trial 1, 60 English crossbred yearling steers (283 +/- 6.7 kg) were used in a completely randomized design with four dietary treatments. Treatments were diets with no corn bran, dry corn bran (86% DM), wet corn bran (37% DM), and rehydrated dry bran (37% DM). Bran was fed at 40% of dietary DM. All finishing diets had (DM basis) 9% corn steep liquor with distillers solubles, 7.5% alfalfa hay, 3% tallow, and 5% supplement. Gain efficiency and ADG were greater (P < 0.01) for cattle fed no corn bran compared with all treatments containing corn bran; however, no differences were detected across corn bran types. In Trial 2, 340 English crossbred yearling steers (354 +/- 0.6 kg) were used in a randomized block design with treatments assigned based on a 2 x 4 + 2 factorial arrangement (four pens per treatment). One factor was the corn processing method used (dry-rolled corn, DRC; or steam-flaked corn, SFC). The other factor was corn bran type: dry (90% DM), wet (40% DM), or dry bran rehydrated to 40 or 60% DM. Bran was fed at 30% of dietary DM, replacing either DRC or SFC. Two control diets (DRC and SFC) were fed with no added bran. All finishing diets contained (DM basis) 10% corn steep liquor with distiller's solubles, 3.5% alfalfa hay, 3.5% sorghum silage, and 5% supplement. Corn bran type did not affect DMI (P = 0.61), ADG (P = 0.53), or G:F (P = 0.10). Dry matter intake was greater (P < 0.01) by steers fed bran compared with those fed no bran, and was greater by steers fed DRC than by steers fed SFC (P < 0.01). Interactions occurred (P < 0.01) between grain source and bran inclusion for ADG and G:F. The ADG by steers fed the SFC diet without bran was greater (P < 0.01) than by steers fed SFC diets with bran, whereas the ADG by steers fed DRC diets with or without bran was similar. Daily gain was 15.2% greater (P < 0.01) by steers fed SFC without bran than by steers fed DRC without bran. Gain efficiency was 16.9% greater (P < 0.01) for steers fed SFC without bran compared with steers fed DRC without bran. In DRC and SFC diets, feeding bran decreased (P < 0.01) G:F by 5.2 and 13.8%, respectively. The moisture content of corn bran had no effect on finishing steer performance, and drying corn bran did not affect its energy value in finishing cattle diets.  相似文献   

15.
To measure the effects of dietary fat on feedlot performance and carcass characteristics, and on beef appearance, moisture binding, shelf life, palatability, and fatty acid content, 126 crossbred beef steers (321.1 +/- 0.57 kg of BW) were allotted to a randomized complete block (3) design with a 3 x 2 + 1 factorial arrangement of dietary treatments. The main effects were level of yellow grease (0, 3, or 6%) and alfalfa hay (3.5 or 7%) in corn-based diets containing 15% potato by-product (PB). The added treatment was 6% tallow and 7% alfalfa in a barley-based diet containing 15% PB. Dry matter intake and ADG were not affected by diet; however, G:F and diet NE content increased linearly (P < 0.10) with yellow grease. Kidney, pelvic, and heart fat (2.0 to 2.3 +/- 0.07) and yield grade (2.8 to 3.1 +/- 0.09) increased linearly (P < or = 0.05) with yellow grease. Steers fed corn plus 6% yellow grease had lower (P < 0.05) beef firmness and beef texture scores but greater (P < 0.01) fat color score than those fed barley plus 6% tallow. Moisture retention of beef was not affected by dietary treatment, except purge score during retail storage, which was decreased linearly (P < 0.01) from 2.1 to 1.6 +/- 0.06 by level of yellow grease. Steaks from steers fed barley plus 6% tallow had greater (P < 0.05) shear force than those from steers fed corn plus 6% yellow grease, and beef flavor increased linearly (P < 0.05) from 6.2 to 6.7 +/- 0.11 as the level of yellow grease increased. Level of yellow grease linearly increased (P < 0.01) transvaccenic acid (TVA) by 61% and CLA content of beef by 48%. Beef from steers fed corn plus yellow grease had lower (P < 0.05) palmitoleic and oleic acids and greater (P < 0.05) linoleic, TVA, and CLA than beef from steers fed the barley-tallow diet. Feeding yellow grease increased diet energy content, which increased carcass fatness, and altered beef fatty acid content, which increased beef flavor without affecting moisture retention, shelf life, or cooking properties of the beef. Additionally, beef from steers fed corn plus 6% yellow grease was more tender and had more polyunsaturated fatty acid content and CLA than beef from steers fed barley plus 6% tallow.  相似文献   

16.
Two trials were conducted to examine the influence of flake density (FD) on the feeding value of steam-flaked corn. Treatments consisted of corn that had been steam-flaked to mean densities of .42, .36 and .30 kg/liter (28, 24 and 20 lb/bu). In Trial 1, treatment effects on characteristics of digestion were evaluated using three crossbred steers with cannulas in the rumen and proximal duodenum. In Trial 2, treatment effects on feedlot performance were evaluated in a 112-d finishing trial involving 72 crossbred steers with an average initial weight of 312 kg. Flake density was directly related to flake thickness (P less than .01) and inversely related (P less than .01) to in vitro enzymatic digestibility of starch. Decreasing the FD resulted in a linear decrease (P less than .01) in ruminal pH and linear increases (P less than .05) in postruminal and total tract digestibility of starch. Postruminal digestibility of N and total tract digestibility of OM, N and energy also increased linearly (P less than .05) with decreasing FD. Flake density did not influence (P greater than .10) feedlot performance or carcass merit. There was a tendency (P greater than .10) for depressed rate and efficiency of gain for steers fed the 30 kg/liter FD corn. Improvements in digestibility and N utilization of SF corn-based diets as a result of decreasing FD from .42 to .30 kg/liter did not enhance feedlot performance. This may be due to digestive dysfunction, perhaps related to processing effects on ruminal pH.  相似文献   

17.
Hanwoo (Korean native) steers (274.8 ± 4.6 kg) with ruminal and duodenal cannulae were used in a 4 × 4 Latin square design experiment to examine the effects of dietary treatments on starch disappearance in the gastrointestinal tract. Dietary treatments consisted of concentrate that were based on ground corn with soybean meal (C‐SBM), ground corn with corn gluten meal (C‐CGM), ground barley with soybean meal (B‐SBM) and ground barley with corn gluten meal (B‐CGM). Although the intakes of starch and protein for steers fed experimental diets were different, it did not change ruminal pH and total volatile fatty acid concentrations. Average duodenal CP flow and quantity of CP apparently digested post‐ruminally was higher (P = 0.001) for CGM‐based diets than SBM‐based diets. There were increases in quantity (P < 0.001) and percentage (P < 0.001) of corn starch digested post‐ruminally compared to barley starch. Synchronized diets showed higher percentages (P = 0.03) of starch apparently digested post‐ruminally than asynchronization. Hanwoo steers fed a corn‐based diet with a large quantity of starch reaching the duodenum and fed C‐CGM supplying great amounts of protein to the small intestine may have contributed to increased post‐ruminal starch digestion.  相似文献   

18.
Three studies were performed to examine the effect of starch and protein digestion rates on N retention in grower pigs. In Exp. 1, the glycemic index (GI) of corn, a malting barley, and a slow-rumen-degradable barley (SRD-barley) were measured using 6 barrows (BW = 18.0 ± 0.5 kg). The GI of malting barley was greater (P < 0.05) than that of SRD-barley (71.1 vs. 49.4), and the GI of both barley cultivars was less (P < 0.05) than that of corn (104.8). In Exp. 2, the standardized ileal digestibility of AA and DE content of the 3 ingredients were determined using 5 ileal-cannulated barrows (BW = 20.7 ± 2.3). The apparent total-tract energy digestibility values of corn (86.1%) and malting barley (85.7%) were greater (P < 0.05) than that of SRD-barley (82.3%). The standardized ileal digestibility of Lys was 94.0, 92.6, and 92.4% for corn, malting barley, and SRD-barley, respectively, and did not differ among grains. In Exp. 3, 6 diets were formulated to equal DE (3.40 Mcal/kg), standardized ileal digestibility of Lys (8.6 g/kg), starch (424.9 g/kg), and digestible CP (180.0 g/kg) using the values obtained in Exp. 2. Three GI [high (corn), medium (malting barley), and low (SRD-barley)] and 2 rates of protein digestion [rapid (soy protein hydrolysate) and slow (soy protein isolate)] were tested in a 3 × 2 factorial arrangement with 36 barrows (BW = 32.2 ± 2.5 kg). Pigs were fed 3.0 times the maintenance energy requirement daily in 2 meals for 2 wk and were housed in metabolic crates to collect feces and urine separately. At the end of the study, intestinal contents were collected from 4 equal-length segments of the small intestine. The percentage of unabsorbed CP in segment 1 relative to dietary CP was greater (P < 0.05) for the soy protein isolate diet than for the soy protein hydrolysate diet (170.3 vs. 116.5%). The percentages of unabsorbed starch in segments 1 and 2 were greater (P < 0.05) for the SRD-barley diet than for the malting barley or corn diet. Nitrogen intake and fecal N excretion were greater (P < 0.05) for pigs fed the malting barley and SRD-barley diets than for pigs fed the corn diet. Urinary N excretion was greater (P < 0.05) for pigs fed the SRD-barley diet than for pigs fed the corn or malting barley diet. Pigs fed slowly digestible starch (SRD-barley; 46.6%) had less (P < 0.05) net N retention than pigs fed corn or malting barley (54.7 and 54.1%, respectively). In conclusion, slowly digestible starch sources such as SRD-barley may not be suitable to support maximum protein deposition in restricted-fed grower pigs.  相似文献   

19.
Effects of plastic pot scrubbers on feedlot performance and ruminal metabolism of steers fed all-concentrate diets were determined. In Trial 1, 31 crossbred steers (means initial BW, 290 kg) were penned and fed individually. Treatments were 1) 85% concentrate-15% corn silage diet, 2) 100% concentrate diet, and 3) 100% concentrate diet + ruminal insertion of eight plastic pot scrubbers per steer. During the first 112 d of the trial, steer ADG did not differ (P greater than .10) due to treatment. From d 113 to 152, steers provided with pot scrubbers had 16% greater ADG than those fed the 100% concentrate diet without pot scrubbers (P = .18). In Trial 2, 78 crossbred steers (means initial BW, 315 kg) were penned individually and fed the diets used in Trial 1. Steers fed the 100% concentrate diet received zero, four or eight pot scrubbers. From d 113 to 167, steers provided with four or eight pot scrubbers or fed the 85% concentrate diet had greater (P less than .10) gains than steers fed the 100% concentrate diet without pot scrubbers. In Trial 3, 120 steers (means initial BW, 286 kg) were grouped in 12 pens and limit-fed an all-concentrate diet for 84 d. Sixty steers were provided with six pot scrubbers each. Performance was not affected (P greater than .10) by the use of pot scrubbers during the 84-d growing phase. During the subsequent 84-d finishing phase, half the steers receiving each treatment were switched to either an 85% concentrate-15% corn silage or an 100% concentrate diet offered for ad libitum consumption.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
Five ruminally fistulated 3-yr-old mature Holstein steers (average BW 691+/-23 kg) were used in a 5 x 5 Latin square experiment with a 2 x 2 + 1 fact orial arrangement of treatments. Effects of protein concentration and protein source on nutrient digestibility, excretion of DM and fecal N, ruminal fluid volume and dilution rate, ruminal characteristics, and in situ DM disappearance of whole shelled corn, ground corn, and orchardgrass hay were measured in steers limit-fed high-concentrate diets at 1.5% of BW. A negative control basal diet (NC; 9% CP) was supplemented to achieve either 11 or 14% CP; supplemental CP was either from soybean meal (11 and 14% SBM) or a 50:50 ratio of CP from urea and soybean meal (11 and 14% U). Dry matter and OM digestibilities were 5% greater (P < .07) for steers fed the SBM diets than for those fed the U diets. Starch digestibility did not differ (P > .10) among steers fed any of the diets. Nitrogen source did not affect (P > .10) apparent N digestibility or fecal N excretion; however, steers fed the NC diet had the lowest (P < .10) apparent N digestibility compared with those fed all other diets. Ruminal fluid volume was lower (P < .06) when steers were fed the NC diet compared with all other diets; there were no differences (P > .74) among diets for ruminal fluid dilution rate. In general, ruminal ammonia N and VFA molar proportions were not affected by protein source or concentration. Although CP concentration affected (P < .06) in situ DM disappearance of ground corn, CP concentration did not (P > .48) affect total tract digestion of DM or OM. This indicates that CP concentration may have affected site of digestion, but not extent of digestion. When mature ruminants were limit-fed a corn-based diet to meet primarily a maintenance function, protein source and concentration had little effect on measures of nutrient digestion.  相似文献   

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