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1.
One hundred thirty crossbred steers (324 kg) were used in a 121-d comparative slaughter trial to evaluate the feeding value of fat in steam-flaked corn- (SFC) or wheat- (SFW) based diets. Treatments consisted of an 88% concentrate finishing diet containing 1) SFC, no fat; 2) SFC, 6% yellow grease (YG); 3) SFC, 6% cottonseed oil soapstock (COS); 4) SFW, no fat; 5) SFW, 6% YG; and 6) SFW, 6% COS. There were no interactions (P greater than .10) between grain type and performance response to supplemental fat. Fat supplementation increased (P less than .05) ADG by 7.3% and decreased (P less than .01) DMI/gain by 10.6%. Fat supplementation decreased (P less than .05) ruminal OM digestion by 5% and net flow of microbial N to the small intestine by 14.5% but did not affect (P greater than .10) total tract digestion of OM, ADF, or starch. Substituting SFW for SFC did not influence (P greater than .10) ADG but tended (P greater than .10) to increase DMI/gain and decreased (P less than .05) the NEm and NEg of the diet by 3.4 and 4.3%, respectively. Ruminal OM digestion was similar (P greater than .10) for SFC and SFW. Flow of microbial N to the small intestine was 12% greater (P less than .05) with SFW. Total tract digestibilities of OM and starch were similar (P greater than .10) for both grains. However, ADF digestion was lower (34%, P less than .01) with SFW. It is concluded that the feeding value of supplemental fat is similar for wheat- and corn-based finishing diets. The performance response to supplemental YG and COS was similar. The NEm and NEg values of YG were 6.35 and 4.93 Mcal/kg, respectively, whereas the corresponding values for COS were 5.69 and 4.60 Mcal/kg. Supplementation of growing-finishing diets with up to 6% (.45 kilograms/day) of fat did not directly influence body composition. The NE value of SFW was approximately 96% of the value of SFC.  相似文献   

2.
Two experiments were conducted to evaluate the comparative feeding value of dried shredded sugarbeets (DSSB; 0, 20, and 40% of diet DM) as a replacement for steam-flaked corn (SFC) in finishing diets for feedlot cattle. In Exp. 1, 60 calf-fed Holstein steers (476 ± 6.3 kg) were used in a 97-d finishing trial. Substitution of SFC with DSSB did not affect ADG or DMI (P > 0.20). Increasing DSSB decreased gain efficiency (ADG:DMI; linear effect, P = 0.04) and dietary NE (linear effect, P = 0.03). Given that SFC has a NE(m) value of 2.38 Mcal/kg, the replacement NE(m) and NE(g) values for DSSB were 1.94 and 1.29 Mcal/kg, respectively. There were no treatment effects (P > 0.20) on carcass characteristics. In Exp. 2, 6 cannulated Holstein steers (205 kg) were used in a replicated 3 × 3 Latin square design to evaluate treatment effects on digestion. Ruminal digestion of starch, NDF, and feed N were not affected (P > 0.10) by DSSB, although ruminal OM digestion tended to increase (linear effect, P < 0.08). Replacing SFC with DSSB decreased flow of starch to the small intestine, but it increased flow of microbial N (linear effect, P = 0.05). There were no treatment effects (P > 0.14) on postruminal digestion of OM, NDF, starch, or feed N or total tract digestion of OM, starch, and N. Substitution of DSSB increased (linear effect, P = 0.05) total tract NDF digestion and decreased (linear effect, P = 0.05) dietary DE (Mcal/kg). Given that SFC has a DE value of 4.19 Mcal/kg, the replacement DE value of DSSB was 3.68 Mcal/kg. There were no treatment effects (P > 0.12) on ruminal pH or total VFA; however, DSSB decreased propionate (linear effect, P = 0.05) and increased acetate (linear effect, P = 0.07), butyrate (linear effect, P = 0.05), valerate (linear effect, P = 0.04), and estimated methane production (linear effect, P = 0.05). We concluded that DSSB may replace SFC in finishing diets at levels of up to 40% without detrimental effects on ADG and carcass characteristics. The NE value of DSSB is 82% that of SFC (DM basis). Partial replacement of SFC with DSSB alters ruminal VFA patterns, increasing estimated methane energy loss and slightly decreasing the efficiency of DE utilization.  相似文献   

3.
Four Holstein steers (212 kg) with cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square experiment to study the influence of degree of ruminal biohydrogenation (BH) on the feeding value of supplemental fat. Treatments consisted of an 88% concentrate finishing diet supplemented with 1) 2% yellow grease (control); 2) 4% formaldehyde-protected fat (Rumentek), 2% yellow grease (LBH); 3) 2% Rumentek, 4% yellow grease (MBH); or 4) 6% yellow grease (HBH). Ruminal BH of HBH, MBH, and LBH diets was 74, 68, and 54%, respectively. High-fat supplementation decreased (7%, P < .05) intestinal digestibility of 18:0 but increased intestinal digestibility of 18:1 (3%, P < .10), 18:2 (14%, P < .01), and 18:3 (23%, P < .05). Increases in intestinal digestibility of 18:0 (quadratic effect, P < .05), 18:1 (linear effect, P < .01), 18:2 (linear effect, P < .01), 18:3 (linear effect, P < .05), and total fatty acids (linear effect, P < .05) were inversely related to BH. For every 1% increase in the proportion of 18:1 fat entering the small intestine, the digestibility of 18:0 increased 1%. High-fat supplementation depressed ruminal digestion of OM (11%, P < .05), NDF (16%, P < .05), starch (6%, P < .05), and feed N (12%, P < .01). Formaldehyde-protein protection of fat diminished its depressing effects on ruminal digestion of NDF (quadratic effect, P < .10) and enhanced ruminal escape of feed N (linear effect, P < .10). Postruminal digestion of OM was greater (4.6%, P < .10) for high-fat diets. High-fat diets decreased (P < .05) total tract digestion of OM (1.9%), NDF (7.4%), and starch (.5%). Postruminal and total tract digestibility of OM, NDF, N, and starch was not affected (P > .10) by BH. In a 125-d finishing trial, 100 yearling steers (362 kg) were used to evaluate treatment effects on growth performance. High-fat diets did not affect (P > .10) ADG but increased (P < .10) feed efficiency (9%, P < .10), dietary NEm (7.6%, P < .05), and dressing percentage (9%, P < .05). The magnitude of the increase in dressing percentage was inversely related (linear effect, P < .10) to BH. We conclude that decreasing ruminal BH will increase postruminal digestibility of fat, and hence the NE value of dietary fat. The synergistic effect of increasing the proportion of 18:1 on intestinal digestion of fat enables higher levels of fat supplementation. Protecting fat from BH minimizes the detrimental effects of supplemental fat on fiber digestion.  相似文献   

4.
A feedlot growth-performance trial and a metabolism trial were conducted to evaluate the comparative feeding value of tapioca pellets (TP). In the growth-performance trial treatments consisted of a steam-flaked corn (SFC)-based finishing diet in which a blend of 86% TP and 14% peanut meal replaced SFC at the rate of 0, 15, or 30% of diet DM. Daily weight gain (P less than .10) and DM intake (P less than .01) were greatest when 15% of the diet DM consisted of TP. Feed/gain increased linearly (P less than .01) with TP substitution into the diet. Treatment effects on carcass merit were small (P greater than .10), except that marbling score was greater with 15% TP than with either 0 or 30% TP. In the metabolism trial involving four Holstein steers, treatments consisted of an 88% concentrate diet containing 67% of either SFC or TP. Ruminal and total tract digestibility of starch was similar (P greater than .10) for SFC and TP, averaging 91 and 99%, respectively. Postruminal (P less than .05) and total tract (P less than .01) digestibility of N was lower for the TP than for the SFC diet. Total tract digestibility of N in TP was 3%. Little, if any, ADF in TP was fermented in the rumen. Total tract digestibility of ADF in TP was 16%. Total tract digestibility of DM (P less than .01) and OM (P less than .05) decreased 7 and 5%, respectively, with TP substitution for SFC. Virtually all the difference in OM digestibility could be attributed to differences in ADF excretion. The DE value of the diet decreased 11.5% (P less than .01) with the substitution of TP for SFC. It was concluded that TP can replace up to 30% of the DM in growing-finishing diets without adversely affecting ADG or DM intake of feedlot cattle. Tapioca pellets have approximately 86% the NE value of SFC.  相似文献   

5.
Two experiments were conducted to determine the effects of wet distillers grain plus solubles (WDG; <15% sorghum grain) concentration in steam-flaked corn (SFC) diets on feedlot performance, carcass characteristics, ruminal fermentation, and diet digestibility. In Exp. 1, six hundred crossbred steers (364 ± 35 kg of BW) were used in a randomized complete block design with 8 replications/treatment. Dietary treatments consisted of a dry-rolled corn (DRC) control diet without WDG, a SFC control without WDG, and SFC with 4 WDG concentrations (15, 30, 45, 60% DM basis) replacing SFC, cottonseed meal, urea, and yellow grease. Final BW, ADG, G:F, HCW, and 12th-rib fat depth were greater (P ≤ 0.05) for SFC compared with DRC. Dry matter intake tended (P = 0.06) to be greater for DRC compared with SFC. Final BW, ADG, G:F, HCW, 12th-rib fat depth, and marbling score decreased linearly (P < 0.01) with increasing WDG concentration. In Exp. 2, six ruminally and duodenally cannulated crossbred steers (481 ± 18 kg of BW) were used in a 6 × 6 Latin square design using the same diets as Exp. 1. Ruminal, postruminal, and total tract OM and NDF digestibility were not different (P > 0.14) for DRC compared with SFC. Ruminal and total tract starch digestibility were greater (P < 0.01) for SFC compared with DRC. Dry matter and OM intake were not different (P ≥ 0.43) among WDG treatments. Ruminal and total tract OM digestibility decreased linearly (P < 0.01) with increasing WDG concentration. Intake, ruminal digestibility, and total tract digestibility of NDF increased linearly (P < 0.01) with increasing WDG concentration. Starch intake decreased linearly (P < 0.01) with increasing WDG concentration. Ruminal starch digestibility increased (P = 0.01) with increasing concentration of WDG. Total tract starch digestibility decreased quadratically (P < 0.01) with increasing concentration of WDG. Feeding SFC improved steer performance compared with DRC. The concentration of WDG and corn processing method influences nutrient digestibility and ruminal fermentation. The addition of WDG in SFC-based diets appears to negatively affect animal performance by diluting the energy density of the diet.  相似文献   

6.
Six beef steers (British x Brahman) cannulated at the rumen, duodenum and ileum (avg wt 334 kg) and three mature steers (British x British) cannulated at the esophagus were used in a replicated 3 x 3 latin square design and fed no supplement (C), .5 kg soybean meal (SBM) or .5 kg steam-flaked sorghum grain (SFS).head-1.d-1 (DM basis) while grazing blue grama rangeland. Periods of the latin square included a minimum of 14 d for adaptation and 11 d for esophageal masticate collection and digesta sampling. In September, October and November, respectively, forage collected by esophageally cannulated steers averaged 74.5, 88.8 and 71.0% grasses; 2.06, 1.53 and 1.77% N and 68.3, (P greater than .10) by treatment, but total N intake was greater (P less than .05) for SBM vs C and SFS treatments. No differences (P greater than .10) were detected among treatments in OM, NDF, ADF and N digestibilities in the rumen, small intestine or hindgut, but total tract OM digestibility was greater (P less than .10) for SBM and SFS than for C, and total tract N digestibility was greater (P less than .10) for SBM than for C or SFS. Duodenal ammonia N flow was greater (P less than .05) when SBM was fed that when SFS and C were fed, but microbial N and non-ammonia, non-microbial N flows and microbial efficiency were not altered by treatment. Likewise, ileal N flow was not affected (P greater than .10) by treatment. Particulate passage rate, gastrointestinal mean retention time, forage in vitro OM disappearance and in situ rate of forage NDF digestion also were not affected (P greater than .10) by treatments. Ruminal fluid volume was greater (P less than .05) for SFS vs SBM and C treatments, but no differences were noted in fluid dilution rate. Ruminal fluid ammonia concentration was greater (P less than .05) when SBM was fed than when SFS and C were fed (13.5, 9.9 and 8.7 mg/dl, respectively), whereas pH and total VFA concentrations were not different (P greater than .10). Proportion of acetate in ruminal fluid was less (P less than .10) for SBM and SFS than for C. Small amounts of supplemental SBM and SFS had little effect on forage intake, ruminal fermentation and site of digestion but both increased total tract OM digestion in steers grazing blue grama rangeland.  相似文献   

7.
To determine the effects of blends of high-moisture harvested sorghum grain (HMS) and dry-rolled corn (DRC) on site and extent of digestion, high-grain diets were fed to Angus-Hereford heifers (315 kg) in a 5 x 5 latin square. The grain portion consisted of ratios (HMS:DRC) of 0:100, 25:75, 50:50, 75:25 and 100:0. Heifers were equipped with ruminal, duodenal and ileal T-type cannulas. Digestibilities of OM (P less than .05) and non-ammonia nitrogen (NAN; P less than .01) in the total tract declined linearly as HMS replaced DRC. Chyme flow (liters/d) through the duodenum increased linearly (P less than .01), and true ruminal OM disappearance tended to decline linearly (P less than .10) as HMS replaced DRC. A quadratic response (P less than .05) in extent of starch disappearance (g/d) in the rumen was noted; blends were lower than either individual grain. Ruminal escape of feed N tended to be quadratic (P less than .10); values for individual grain types were greater than blends. Microbial efficiency increased linearly (P less than .05) as HMS replaced DRC. Extent of starch digestion in the rumen averaged 82.7% compared to only 2.9% in the small intestine and 5.7% in the large intestine. Altering the ratio of HMS to DRC appeared to have more effect on ruminal fermentation than on digestion in the small intestine; most starch and nitrogen responses were quadratic. Increases in ruminal pH and chyme flow, potentially caused by increased salivary flow, may cause non-linear changes in the solubility of proteins in HMS and DRC, when fed as blends, altering the digestibility of protein and starch from values predicted from the individual grains.  相似文献   

8.
Five ruminally and duodenally cannulated steers were fed bromegrass hay (H; 5.6% CP; 70.9% cell wall) substituted with 0, 15, 30, 45, or 60% soybean hulls (SH; 10.5% CP; 87.9% cell wall) at 90% of ad libitum DMI. Diets were made isonitrogenous (11% CP) by addition of isolated soybean protein (91.5% CP). Total ruminal VFA concentration, molar proportion of acetate, and molar acetate:propionate ratio increased (linear; P less than .02) with increasing level of SH substitution, but propionate (mol/100 mol) and ruminal fluid passage rate decreased (linear; P less than .01). Ruminal pH and ammonia concentration decreased more rapidly, and to a greater extent and duration, as level of SH increased; neither was decreased to levels considered detrimental to fiber digestion. Ruminal and total tract DM, OM, and cell wall digestibilities increased (linear; P less than .01), whereas total tract N digestibility decreased (linear; P = .03), as level of SH increased Total N flow to the duodenum increased (linear, P = .03) with increasing level of SH, and microbial N flow tended (cubic, P = .09) to increase. Microbial efficiencies were unchanged (P = .10) with SH level. True ruminal digestibilities of N did not differ (P greater than .10) among diets. Rate of in situ DM disappearance of H and SH was not influenced (P greater than .10) by SH substitution, although rate tended to be fastest with 30 and 45% SH (quadratic, P = .14). We infer from these data that SH can replace 60% of the DMI of a low-quality forage diet without decreasing OM or cell wall digestion.  相似文献   

9.
Two experiments were conducted to determine how varying the proportion of wheat (W) and high-moisture sorghum grain (SG) in 80% grain dies would affect ruminal fermentation, liquid and solid flow, site and extent of digestion (Exp. 1) and feeding performance of cattle (Exp. 2). In Exp. 1, three ruminal, duodenal and ileal cannulated steers (average weight 295 kg), fed at 1.54% of body weight, were used in a six-period crossover design. Treatments were: W, 50W:50SG (W:SG) and SG. Increasing wheat level decreased ruminal pH, molar proportion of acetate, and acetate:propionate ratio (P less than .05) and increased (P less than .05) L-lactate concentration, molar proportions of propionate and valerate and total volatile fatty acid concentration. Ruminal liquid dilution and outflow rates were faster (P less than .05) and retention time was shorter (P less than .05) for the W diet. Duodenal and ileal liquid flow increased (P less than .05), and solid flow decreased (P less than .05), as dietary level of wheat increased. Apparent ruminal digestion (% of intake) of dry matter (DM) and organic matter (OM) was greater (P less than .01) with the wheat-containing diets. Intestinal DM and OM digestion (percent of intake) was higher (P less than .05) with the SG and W:SG diets. Ruminal, small intestine, large intestine and total tract starch digestion (percent of intake) was 93.5, 5.6, .7, 99.8, 71.5, 20.4, 5.7, 97.6; and 48.0, 32.5, 10.5, 91.0 with the W, W:SG and SG diets, respectively. In Exp. 2, group-fed (24 pens) steers (avg initial weight 341 kg) were fed ad libitum once daily for 121 d. Treatments were: W, 67W:33SG, 33W:67SG and SG. Rates of gain (kg/d) with the W (1.32), 67W:37SG (1.33) and 33W:67SG (1.30) diets were similar (P greater than .05), but faster (P less than .05) than those with the SG diet (1.16). Feed intake was lower (P less than .01) with the W and 67W:33SG diets, but the wheat-containing diets were utilized more efficiently (P less than .01). Increasing the proportion of wheat in sorghum grain feedlot diets improved cattle performance by optimizing ruminal and post-ruminal digestion.  相似文献   

10.
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   

11.
Four Holstein steers (282 kg) with cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square experiment to evaluate the influence of dietary urea level (0, 0.4, 0.8, and 1.2%, DM basis) in a steam-flaked barley-based finishing diet on digestive function. There were no treatment effects (P > 0.20) on ruminal digestion of OM and ADF. Increasing dietary urea level increased (linear, P < 0.01) ruminal starch digestion. Ruminal degradability of protein in the basal diet (no supplemental urea) was 60%. Increasing dietary urea level did not increase (P > 0.20) ruminal microbial protein synthesis or nonammonia N flow to the small intestine. There were no treatment effects (P > 0.20) on total-tract ADF digestion. Total tract digestion of OM (quadratic, P < 0.01) and starch (linear, P < 0.05) increased slightly with increasing urea level. Urea supplementation increased (linear, P < 0.01) ruminal pH 1 h after feeding; however, by 3 h after feeding, ruminal pH was lower (cubic, P < 0.05) with urea-supplemented diets. Urea supplementation did not affect (P > 0.20) ruminal molar proportions of acetate and propionate. One hundred twenty crossbred steers (252 kg; approximately 25% Brahman breeding) were used in an 84-d feeding trial (five pens per treatment) to evaluate treatment effects on growth performance. Daily weight gain increased (linear, P = 0.01) with increasing urea level, tending to be maximal (1.53 kg/d; quadratic, P = 0.13) at the 0.8% level of urea supplementation. Improvements in ADG were due to treatment effects (linear, P < 0.01) on DMI. Urea supplementation did not affect (P > 0.20) the NE value of the diet for maintenance and gain. Observed dietary NE values, based on growth performance, were in close agreement with expected based on tabular values for individual feed ingredients, averaging 100.4%. We conclude that with steam-flaked barely-based finishing diets, ruminal and total-tract digestion of OM and ruminal microbial protein synthesis may not be increased by urea supplementation. In contrast, ADG was optimized by dietary inclusion of 0.8% urea. Urea supplementation may not enhance the net energy value of steam-flaked barely-based finishing diets when degradable intake protein is greater than 85% of microbial protein synthesis.  相似文献   

12.
Six ruminally and duodenally cannulated yearling steers (523 kg) were used in a replicated 3 x 3 Latin square design experiment to study the effects of corn processing on nutrient digestion, bacterial CP production, and ruminal fermentation. Dietary treatments consisted of 90% concentrate diets that were based on dry-rolled (DRC), high-moisture (HMC), or steam-flaked (SFC) corn. Each diet contained 2.0% urea (DM basis) as the sole source of supplemental nitrogen. Each period lasted 17 d, with d 1 through 14 for diet adaptation and d 15 through 17 for fecal, duodenal, and ruminal sampling. Dry matter and OM intakes were similar for DRC and SFC but were approximately 15% higher (P < 0.05) for HMC. True ruminal OM digestibilities were 18 and 10% greater (P < 0.05) for HMC than for DRC or SFC, respectively. Ruminal starch digestibilities were similar between HMC and SFC and were approximately 19% greater (P < 0.05) than DRC. Postruminal OM digestibility was similar among treatments; however, postruminal starch digestibility was 15% greater (P < 0.05) for SFC than for DRC or HMC, which were similar. Total-tract DM and OM digestibilities were similar between HMC and SFC and were 4% greater (P < 0.05) than DRC. Likewise, total-tract starch digestibilities were similar between HMC and SFC and were 3% greater (P < 0.05) than DRC. Bacterial CP flow to the duodenum was 29% greater (P < 0.05) for HMC than for DRC or SFC, which were similar. Bacterial N efficiencies were similar among treatments. Based on bacterial CP flow from the rumen, we estimate that dietary DIP requirements are approximately 12% higher for HMC-based diets than for DRC or SFC-based diets, which were similar.  相似文献   

13.
To compare the effects of sorghum grain hybrids on site and extent of digestion, two yellow (Y1 and Y2), two cream (C1 and C2), and two hetero-yellow (HY1 and HY2) sorghum grains were fed (1.85% BW, DM basis) in an 81% dry-rolled grain diet to steers (342 kg BW) equipped with ruminal, duodenal, and ileal cannulas within a 6 X 6 Latin square. Yellow (YEL) hybrids had a homozygous yellow endosperm and a yellow seed coat; cream (CREAM) and hetero-yellow (HET-YEL) hybrids had a heterozygous (partial) yellow endosperm, with white or red seed coats, respectively. Total tract starch digestibility (percentage) was greater (P less than .10) for CREAM and HET-YEL (82.3) than for YEL (78.9), primarily because of greater (P less than .05) starch digestion in the large intestine. Ruminal starch digestibility (percentage) was greater (P less than .10) for HET-YEL (73.2) than for CREAM (66.3) and was a larger proportion of total tract digestion for HET-YEL (90.6) than for CREAM (80.1). Ruminal starch digestion was correlated negatively (r = -.46; P less than .08) with ruminal escape of feed N. Prececal starch digestibility (average 76.2%) was more strongly correlated with ruminal digestibility (r = .69; P less than .01) than with digestion in the small intestine (r = .41; P = .12). Total tract nonammonia N (NAN) digestibility (percentage) was greater (P less than .10) for CREAM than for HET-YEL, greater for Y1 (P less than .10) than for Y2, greater for C2 (P less than .05) than for C1, and greater for HY2 (P less than .05) than for HY1. Flow of NAN to the duodenum was correlated negatively (r = -.55; P less than .05) with prececal starch digestion. Small intestinal NAN disappearance (g/d) was greater (P less than .01) for HY1 (76.0) than for HY2 (52.2). Microbial N flow (r = .88; P less than .01), but not feed N flow (r = .17; P = .52), to the duodenum was correlated with partial NAN digestibility in the small intestine. Hybrids differed in site and extent of digestion. Differences were generally larger for N than for starch.  相似文献   

14.
Two isonitrogenous diets (12.5% CP) containing 20 (20% NPN) or 40% (40% NPN) of the N as nonprotein N were evaluated with 0 or 10 mg laidlomycin propionate (LP)/kg in a 2 x 2 factorial arrangement. Changes in dietary NPN:N ratio were developed by partial substitution of urea N for fish meal N. In Trial 1, four Holstein steers (349 kg) with cannulas in the rumen and proximal duodenum were used to evaluate treatment effects on digestive function. Total tract OM digestion was slightly greater (1.2%, P < .10) for diets containing 20% of N as NPN, due to greater (3.4%, P < .05) postruminal OM digestion. Supplemental LP decreased passage of microbial N to the small intestine (7.4%, P < .10) and ruminal degradation of dietary CP (DIP, 8.1%, P < .10). Decreasing the NPN:N ratio decreased microbial N flow to the small intestine (7.5%, P < .10) and DIP (15%, P < .01) and increased (6%; P < .05) the flow of indispensable amino acids to the small intestine. Supplemental LP increased (P < .10) ruminal pH. There were no treatment effects (P > .10) on ruminal molar proportions of acetate or propionate. In Trial 2, 120 Holstein steers (122 kg) were used to evaluate treatment effects on growth performance. Decreasing the NPN:N ratio increased ADG (P < .01) by 36, 40, and 16%, respectively, for the initial three 56-d periods of the trial. Overall, ADG was 17% greater (P < .01) for cattle consuming diets containing 20 vs 40% NPN. Decreasing the NPN:N ratio increased (P < .01) gain efficiency by 17 and 14%, respectively, for the initial two 56-d periods. Overall, gain efficiency was 6% greater (P < .01) for diets containing 20% NPN. Dietary NPN:N ratio did not influence (P > .10) the NE value of diets. Supplemental LP did not affect DMI (P > .10) but increased ADG (6%, P < .01) and gain efficiency (5%, P < .05) and decreased (11%, P < .05) the maintenance energy requirements. Protein nutrition limited growth performance of calves receiving the 20% NPN diets during the initial 112 d of the trial. With the 40% NPN diets, protein nutrition limited growth performance throughout most of the trial (d 1 to d 224). We conclude that LP will enhance daily weight gain and gain efficiency of calf-fed Holstein steers. Conventional urea-based diets will not diminish response to LP, although they may not meet the metabolizable amino acid requirements of calf-fed Holsteins during the first three-quarters of the feeding period.  相似文献   

15.
Four beef heifers (211 kg) fitted with ruminal, duodenal and ileal cannulae (T-type), were fed a high-concentrate diet with a low (L) or high (H) level of N (1.71 and 2.18%, respectively), and received daily doses of either saline (S) or an antibiotic (A) mixture (2 g neomycin sulfate and .25 g bacitracin) into the terminal ileum in a 4 X 4 Latin-square experiment. Added N increased ruminal NH3-N concentration and tended to increase efficiency of microbial growth and to decrease ruminal disappearance of organic matter, starch and protein. Administration of antibiotics into the ileum reduced nucleic acid content of feces (P less than .05), tended to reduce digestion of organic matter and starch in the hindgut and total tract and increased ileal pH (P less than .05). Ileal administration of antibiotics increased ruminal escape of feed N by 26 and 42% with the low and high N diets, respectively, and increased ruminal passage rate of particulates. Ruminal N digestion was inversely related to ruminal particulate passage rate (r = -.49; P less than .06). Ruminal liquid passage rate was inversely related to rate of fluid passage through the hindgut and was reduced by ileal administration of antibiotics with the low N diet, but increased by antibiotics with the high N diet. Results indicate that administration of antibiotics into the terminal ileum alters digestive function earlier in the digestive tract including ruminal passage rates and digestion of N in the rumen. Responses were partially modulated by dietary N level.  相似文献   

16.
Influence of steaming time on site of digestion of flaked corn in steers   总被引：3，自引：0，他引：3  
Four crossbred steers (395 kg) with cannulas in the rumen, proximal duodenum and distal ileum were used to evaluate effects of steaming time of corn on characteristics of digestion. The basal diet contained (DM basis) 12% forage-and 75% corn. The corn portion of the diet was provided as either dry-rolled (DR) or steam-flaked (SF), which had been exposed to steam for 34, 47 or 67 min prior to flaking to a mean density of .34 kg/liter. Longer steaming times linearly increased in vitro reactivity of corn starch to amyloglucosidase. Steaming time had a quadratic effect (P less than .05) on ruminal starch digestion. Ruminal starch digestibility of corn steamed for 47 min was 7% less than for corn steamed for 34 or 67 min. Longer steaming time linearly increased (P less than .05) flow of non-ammonia N to the small intestine with the principal increase (5.4%) between 34 and 47 min steaming time. Steaming time did not influence (P greater than .10) small intestinal or total tract digestibility of OM, starch or N. Compared with DR, SF increased (P less than .01) ruminal, small intestinal and total tract digestibility of starch 21.9, 75.1 and 9.2%, respectively. Although SF resulted in marked improvements in digestibility over DR, steaming times greater than 34 min were not beneficial.  相似文献   

17.
Two digestion and slaughter trials were conducted to evaluate the influence of limestone level on site and extent of digestion and rumen fermentation in lambs. In trial 1, 11 wether lambs (avg wt 40.7 kg) were fed 75% concentrate diets supplemented with .6, 1.5 or 3.0% limestone (.6,1.2,1.7% dietary Ca, respectively) in a completely randomized design. Dry matter intake increased linearly (P less than .10) with limestone level; therefore, other data were analyzed with dry matter intake as a covariate. Total tract organic matter digestion decreased linearly (P less than .05) with increasing limestone but dry matter and fiber digestion were not affected by limestone. Ruminal digestion of dry matter and organic matter declined linearly (P less than .05) with increasing limestone. Ruminal neutral detergent fiber (NDF) digestion was higher with the 1.5 than the .6 and 3.0% limestone diets (quadratic effect, P less than .05) but ruminal digestion of other fiber components was not affected by limestone. Ruminal volatile fatty acids were not affected by limestone level; however, rumen ammonia concentrations decreased linearly (P less than .05) with increasing limestone level. In trial 2, 12 wether lambs (avg wt 43.3 kg) were fed a 35% concentrate diet with .1, 1.5 or 3.0% limestone (.5, 1.2 and 1.6% dietary Ca, respectively) in a completely randomized design. Dry matter intake was not affected by limestone level, but digestibility of dry matter, organic matter and starch (P less than .10), energy, crude protein, acid detergent fiber (ADF) and cellulose (P less than .05) responded quadratically to limestone level, with increases at the 1.5% limestone level. Ruminal dry and organic matter (P less than .05), NDF (P less than .10), ADF (P less than .01), cellulose (P less than .05) and starch (P less than .05) digestion responded quadratically to limestone level with higher values at the 1.5% limestone level. Proportions of ruminal propionate increased linearly (P less than .01) with increasing limestone level and acetate: propionate ratio declined linearly (P less than .01) with limestone level.  相似文献   

18.
Holstein steers (n = 96; 375 kg) were used in a 144-d growth-performance trial to evaluate influence of level (42, 28.5, and 15%) of FFA content on feeding value of yellow grease. Two sources of yellow grease were compared: conventional yellow grease (CYG), containing 15% FFA, and griddle grease (GG), containing 42% FFA. Dietary treatments consisted of an 88% concentrate finishing diet supplemented with either 1) 0% fat, 2) 5% GG, 3) 2.5% GG and 2.5% CYG, or 4) 5% CYG. Fat supplementation increased ADG (11%; P<.05), feed efficiency (9%; P<.05), diet NE (6.4%; P<.05), carcass weight (4%; P<.10), dressing percentage (1%; P<.10), and kidney, pelvic, and heart fat (20%, P<.05). Increasing the FFA in supplemental fat increased (linear effect, P<.10) DM intake, ADG, and feed efficiency and decreased (linear effect, P<.10) retail yield. These improvements in performance were primarily due to increased DM intake. The NEm and NEg values of supplemental fats were not affected by FFA content, averaging 4.98 and 3.85 Mcal/kg, respectively. Treatment effects on characteristics of ruminal and total tract digestion were evaluated using four Holstein steers (180 kg) with cannulas in the rumen and proximal duodenum. Supplemental fat did not influence (P>.10) ruminal or total tract digestion of OM, ADF, starch or N. Postruminal fatty acid digestion was less (P<.10) for fat-supplemented diets than for unsupplemented diets (73.0 vs. 78.6%). The decrease in postruminal fatty acid digestibility with fat supplementation was mainly due to a decreased (16.7%; P<.05) digestibility of C18:0. Postruminal digestibility of the supplemental fat was 68%. There were no treatment effects (P>.10) on ruminal pH. Ruminal biohydrogenation of fatty acids was directly proportional to estimates of methane production. We conclude that the feeding value of conventional yellow grease and griddle grease is similar and that differences in the FFA content of yellow grease will not negatively affect diet acceptability and growth performance of feedlot cattle.  相似文献   

19.
Five crossbred beef cows (Hereford X Angus, 422 kg) with ruminal and duodenal cannulae were used in a Latin square experiment to determine the effects of dietary proportions of fescue and clover hays (0:1, .25: .75, .5:.5, .75:.25 and 1:0) on digestive function. Feed intake was 85% of ad libitum intake of fescue alone (1.03% of body weight). Fescue contained 1.26% nitrogen (N), 71.0% neutral detergent fibre (NDF) and 7.6% acid detergent lignin (ADL), and clover contained 2.43% N 50.0% NDF and 5.8% ADL in DM. Ruminal fluid ammonia-N concentration increased linearly (P less than .05) with declining dietary fescue level. Total concentration of volatile fatty acids in ruminal fluid and duodenal and rectal digesta mean particle size were not affected by fescue level. Ruminal fluid volume and flow rate increased linearly (P less than .05) with increasing dietary fescue, but fluid and particulate digesta passage rates were unchanged. Apparent ruminal organic matter (OM) digestion decreased quadratically (P less than .05) as fescue increased (74.5, 54.3, 49.8, 46.2 and 42.4% for 0, 25, 50, 75 and 100% fescue, respectively). Postruminal OM digestion as a percentage of intake was partially compensatory, increasing linearly (P less than .05) as dietary fescue level rose (2.3, 3.5, 5.1, 8.6 and 11.1% of intake). Thus, total tract OM digestion declined less as fescue replaced clover (76.8, 57.8, 55.0, 54.8 and 53.5%; linear and quadratic, P less than .05) than did apparent ruminal OM disappearance. Changes in ruminal NDF, acid detergent fibre and cellulose digestibilities were similar to those for OM. Microbial growth efficiency increased quadratically (P less than .10) as fescue intake increased. These results indicate that with low feed intake, ruminal and total tract digestion of an all-legume hay diet is greater than that of a grass hay diet. Little or no digestive advantage was achieved by substituting clover for fescue, except in the case of total replacement of fescue with clover, because of concurrent decreases in microbial growth efficiency, microbial N flow to the intestines and OM digestion in the postruminal tract. Negative associative effects in digestion observed between clover and fescue hays in this experiment deserve further study.  相似文献   

20.
Pasteurization of vegetable by-products such as potato slurry (PS) before feeding may be necessary to prevent the spread of pathogens and beef carcass blemishes. We hypothesized that pasteurization would increase ruminal fermentability of PS starch. Four ruminally cannulated crossbred beef steers (initial BW = 432) were used in a 4 x 4 Latin square experiment with a 2 x 2 factorial arrangement of treatments to examine the main effects and interactions of pasteurization (54.4 degrees C for 2 h) of PS and grain type (GT; dry-rolled corn and barley) on ruminal and total tract digestion of beef finishing diets. Diets contained 7% alfalfa hay and 14% PS (DM basis) and were fed ad libitum three times daily. Corn-based diets had 71.7% corn, whereas barley-based diets had 60% barley and 11.7% corn. Pasteurization resulted in greater (P = 0.004) soluble, rapidly degradable starch (34.3 vs. 26.7% for pasteurized and nonpasteurized PS, respectively). Ruminal fluid pH was more acidic (P < 0.07) for corn-based diets than for barley-based diets (P = 0.07) at 0200 and 2100 (sample time x GT; P < 0.05). Ruminal fluid pH was more acidic (P = 0.06) at 1400 for corn-based diets containing pasteurized PS compared with other dietary treatments (sample time x pasteurization x GT; P = 0.04). Minimum and maximum ruminal pH were greater (P < 0.10) for barley-based diets than for corn-based diets. Ruminal fluid pH was < 6.0 for a greater (P = 0.04) proportion of the day for corn-based compared with barley-based diets. In vitro incubation measurements revealed that pasteurization of PS resulted in lower (P = 0.06) ruminal fluid ammonia N concentration. Ruminal fluid ammonia N concentration was lower (P = 0.11) for barley-based diets than for corn-based diets. Steers fed barley-based diets had greater (P = 0.02) DMI and lesser (P < 0.05) total tract digestibility of DM and ADF compared with steers fed corn diets. Pasteurization increased (P = 0.10) total tract starch digestibility. Results indicate pasteurization increased rapidly degradable starch, ruminal starch fermentability, and total tract starch digestibility of PS. Grain type interacted with pasteurization such that feeding corn-based diets containing pasteurized PS resulted in periodic reductions in ruminal pH. Feeding management may be more critical when feeding pasteurized PS in beef finishing diets.  相似文献   

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