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1.
Three digestion experiments and one growth experiment were conducted to determine site, extent and ruminal rate of forage digestion and rate and efficiency of gain by cattle offered alfalfa haylage supplemented with corn or dry corn gluten feed (CGF). In Exp. 1, eight steers were fed alfalfa haylage-based diets with substitution of corn for 0, 20, 40 or 60% of haylage in a 4 X 4 latin square. Increasing dietary corn substitution increased (P less than .05) OM, NDF and ADF digestion by steers but decreased (P less than .05) rate of in situ alfalfa DM digestion. In Exp. 2, five heifers were fed alfalfa haylage-based diets with increasing dietary levels of CGF in a 5 X 5 latin square. Increasing dietary CGF increased (P less than .05) OM, NDF and ADF digestion by heifers. In Exp. 3 and 4, cattle were fed alfalfa haylage-based diets containing either 20 or 60% corn or CGF. In Exp. 3, supplementation increased (P less than .05) OM and NDF digestion but level X supplement source interaction (P less than .05) occurred, with added CGF increasing OM and NDF digestion more than added corn. In Exp. 4, supplementation improved (P less than .05) DM intake, daily gain and feed efficiency. Dry matter intake and daily gain were greater (P less than .05) for 60% supplementation than for 20% supplementation. Overall, whereas increasing the level of dietary supplement increased (P less than .05) OM, NDF and ADF digestion, only corn addition decreased (P less than .05) rate of in situ alfalfa DM digestion. Daily gains and feed efficiencies were similar in cattle fed either corn or CGF with alfalfa haylage.  相似文献   

2.
Two metabolism trials were conducted with yearling steers fed mature native forage to measure the effect of supplemental protein degradability on selected metabolic variables. Supplements contained 40% crude protein equivalence. In Trial 1, four abomasal-cannulated steers weighing 290 to 379 kg were fed supplements containing the following N sources: (1) 15% corn, 85% urea (U); (2) 100% soybean meal (SBM); (3) 10% corn, 40% soybean meal, 50% urea (SBM-U) and (4) 14% corn, 36% blood meal, 50% urea (BM-U). Equal portions of the daily diet (2.2% of body weight) were fed every 2 h. Treatment differences were not significant for organic matter digestibility, abomasal organic matter flow, nonammonia N flow, feed N flow, bacterial N flow and efficiency of microbial protein synthesis. There was a positive (P less than .05) relationship between quantity of slowly degraded protein fed and nonammonia N flow (r = .97) or feed N flow (r = .98). Escape N was determined to be 21.5, 16.5 and 54.2% in SBM, SBM-U and BM-U supplements, respectively. In the second trial, no supplement, SBM, SBM-U and BM-U were fed in a N balance trial. Dry matter, crude protein and neutral detergent fiber digestibilities were higher (P less than .05) for steers fed supplemented diets. Acid detergent fiber digestibility was higher (P less than .05) for steers supplemented with SBM than steers fed the unsupplemented diets. Nitrogen retention was greater (P less than .05) for cattle fed SBM and BM-U than for cattle fed SBM-U or no supplement.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

3.
Two digestion studies were conducted to evaluate the use of pretanned leather shavings as a component of a protein supplement. In Exp. 1, the in situ and in vitro disappearance of pretanned leather shavings and soybean meal was evaluated. Results revealed that less than 18.4% of the pretanned leather shavings was solubilized and disappeared when exposed to McDougall's buffer for 48 h, but there was 90.0% disappearance with 48-h exposure to a .1 N HCl/pepsin treatment and 97.0% disappearance with exposure to a two-stage digestion. In situ disappearance following 72 h in the rumen allowed 6.8% disappearance. Thus, leather shavings seem to be relatively indigestible in the rumen, but postruminal digestion may be possible. In Exp. 2, six Angus x Holstein steers, fitted with ruminal and duodenal cannulas, were used in a replicated 3 x 3 Latin square to evaluate ruminal and digestion effects of the following supplements combined with fescue hay at 1.7% of BW (DM basis): no supplementation (control); supplementation intraruminally with soybean meal at .07% of BW (as-fed basis); and supplementation intraruminally with a combination of soybean meal and pretanned leather shavings (17:8 ratio) at .05% of BW (isonitrogenous to soybean meal; as-fed basis). Ruminal fluid passage rate was greater and fluid turnover time was shorter in steers fed leather shavings than in those fed soybean meal (P = .10). Ruminal pH was lower (P = .04) for supplemented steers than for control steers and ruminal NH3 N concentration was greater (P = .01) in steers fed soybean meal than in those fed leather shavings. Total VFA concentration was increased (P = .02) by supplementation. Supplementation with soybean meal increased (P < .05) ruminal molar proportions of butyrate, valerate, and isovalerate compared with leather shavings. Duodenal OM flow and OM disappearing in the intestines were increased by supplementation (P < .10), but not by the type of supplement fed (P > .10). Ruminal digestion of OM and total tract OM digestion were unaffected (P > .10) by supplementation and the type of supplement fed. Flow and digestion of NDF were unaffected (P > .10) by the treatments. Flow of N and the quantity of N disappearing in the intestines were increased (P < .05) by supplementation but did not differ (P > .10) between supplementation groups. Microbial N flow, N utilization for net microbial protein synthesis, and ruminal N disappearance were unaffected (P > .10) by supplementation and the type of supplement provided. Combining pretanned leather shavings with soybean meal seemed to have no deleterious effects on digestion or fermentation and to allow for escape of some N to the lower tract.  相似文献   

4.
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   

5.
Supplemental corn grain for steers grazing native rangeland during summer   总被引：1，自引：0，他引：1  
Effects of supplemental corn grain on forage OM intake (FOMI), digesta kinetics, ruminal fermentation patterns, in vitro OM digestibility (IVOMD), and in situ OM digestion were examined in steers grazing summer blue grama rangeland in northeastern New Mexico during July and August 1988. Sixteen ruminally cannulated steers (average BW 507 kg) were allotted to four treatments and individually fed whole-shelled corn at 0, .2, .4, and .6% of BW in a complete random design with repeated measurements over time. Forage OMI decreased linearly (P = .02) with increasing levels of supplemental corn; however, a tendency toward greater FOMI, as well as faster particulate and fluid passage, was observed when corn was fed at .2% of BW compared with 0, .4, or .6% of BW. Molar proportions of butyrate increased (P less than .10) but molar proportions of acetate and propionate, ruminal pH, and total VFA concentration did not change (P greater than .10) with added corn. Added corn linearly decreased (P less than .10) ruminal ammonia N concentrations in July, but patterns were inconsistent in August. A cubic response (P less than .05) for in situ OM disappearance with added corn was noted after 24, 72, and 96 h of incubation. Supplemental whole corn fed at .2% of BW had no detrimental effects and tended to increase FOMI. However, supplemental corn fed at .4 or .6% of BW decreased FOMI compared with 0 or .2% of BW.  相似文献   

6.
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   

7.
Six steers (468 kg) with ruminal and duodenal cannulas were fed diets formulated for two levels of energy containing three crude protein (CP) sources in a 6 X 6 Latin square with a 2 X 3 factorial arrangement of treatments. Energy levels were 2.17 and 2.71 Mcal metabolizable energy (ME)/kg dry matter (DM) provided by hay-corn (H) and corn silage-corn (CS) diets, respectively. Soybean mean (SBM), corn gluten meal-urea (CGM) and urea (U) provided 33% of dietary CP in 12% CP diets. Apparent organic matter (OM) digested in the stomach was not affected (P greater than .05) by energy level or CP source, but OM truly digested in the stomach was greater (P less than .05) when steers were fed the CS compared with the H diet. Duodenal flow of non-NH3 N was greater (P less than .05) when steers were fed CS compared with H and when fed SBM or CGM compared with U. Efficiency of bacterial protein synthesis and duodenal bacterial N flow were increased (P less than .05) when steers were fed CS, but non-NH3, nonbacterial N flow to the duodenum was increased (P less than .05) when steers were fed H. When steers were fed CS rather than H, flows (g/d) of bacterial amino acids were greater (P less than .05), but flows of nonbacterial amino acids tended (P less than .08) to be less. Total amino acid flows were not affected (P greater than .05) by energy level. Duodenal flows of total amino acids tended (P less than .06) to be greater when steers were fed CGM compared with SBM or U, due mainly to an increased (P less than .05) flow of nonessential amino acids.  相似文献   

8.
A 2(3) factorial arrangement of treatments was used to study main effects and interactions between particle size of prairie hay (chopped vs ground), two levels of feed intake (60 and 90% of ad libitum) and ruminal degradability of protein sources [dry corn gluten feed (DCGF) vs dry distillers grains (DDG)] on ruminal and total tract digestion in eight ruminal- and duodenal-cannulated steers. Steers were fed every 2 h to approach steady-state feeding conditions. Steers fed ground hay diets digested higher (P less than .05) percentages of total digestible organic matter (OM) and neutral detergent fiber (NDF) in the rumen and had lower (P less than .05) nonammonia-nonbacterial N (NANBN) flows to the duodenum than did those fed chopped hay, probably because greater surface area of ground hay allowed more extensive ruminal fermentation. Protein source X intake interactions were noted for ruminal OM and NDF digestion when expressed as percentages of total digestion. At low intakes, steers fed DCGF had higher (P less than .05) percentages of total digestible OM and NDF disappearing in the rumen than did those fed DDG. Steers fed DCGF had lower total N, NANBN and total amino acid (AA) flows at the duodenum than did those fed DDG, indicating that less DCGF protein escaped ruminal degradation. Steers fed DDG had greater (P less than .05) total tract NDF digestion, suggesting that escape protein from DDG may stimulate hindgut fermentation and thereby affect site and extent of nutrient digestion. Regression analysis indicated that extent of ruminal fermentation and efficiency of microbial growth in vivo are associated with ruminal rates of passage within individual animals. When steers were fed at high-intake levels (1.6% of body weight), ruminal dilution rates were not increased (P less than .05) due to forage particle size or level of intake treatments, accounting, in part, for the lack of expected treatment differences in efficiency of bacterial growth and duodenal N flow, and for the low number of interactions between main effects.  相似文献   

9.
Four Simmental steers with ruminal, duodenal, and ileal cannulas were used to examine effects of dietary forage: concentrate ratio and supply of ruminally degradable true protein on site of nutrient digestion and net ruminal microbial protein synthesis. Steers (345 kg) were fed ammoniated corn cob (high forage; HF)- or corn cob/ground corn/cornstarch (low forage; LF)-based diets supplemented with soybean meal (SBM) or a combination of corn gluten meal and blood meal (CB). Diets were fed at 2-h intervals with average DM intake equal to 2.2% of BW. Feeding LF vs HF increased (P less than .05) OM digestion (percentage of intake) in the stomach, small intestine, and total tract. Efficiency of microbial CP synthesis (EMCP; g of N/kg of OM truly fermented) decreased (P less than .05) for LF vs HF (24.1 vs 26.8), but microbial N and total N flows to the small intestine were similar (P greater than .05) between energy levels (average 112 and 209 g/d, respectively). Total N flows to the small intestine were 13.1% greater (P less than .05) for CB than for SBM because of increased (P less than .05) passage of nonmicrobial N. Feeding SBM vs CB increased (P less than .05) EMCP (27.3 vs 23.3) and microbial N flow to the small intestine (127.5 vs 112.5 g/d), but these increases were not likely due to increased ruminal concentrations of ammonia N (NH3 N). Decreased (P less than .05) incorporation of NH3 N into bacterial N and slower turnover rates of ruminal NH3 N for SBM vs CB suggest that direct incorporation of preformed diet components into cell mass increased when SBM was fed. Results of this study suggest that the inclusion of ruminally degradable protein in the diet may increase the supply of products from proteolysis and that this can increase EMCP and microbial protein flow to the small intestine.  相似文献   

10.
Four multicannulated Holstein steers (initial BW 424 +/- 16 kg) were used in a 4 x 4 Latin square to determine the influence of protein supplementation on forage intake, site and extent of digestion, and nutrient flow in steers consuming dormant bluestem-range forage (2.3% CP). Treatments were 1) control, no supplement; 2) 1.8 kg of low-protein supplement, 12.8% CP (Low-CP); 3) 1.8 kg of moderate-protein supplement, 27.1% CP (Mod-CP); and 4) 2.7 kg of dehydrated alfalfa pellets, 17.5% CP (Dehy). The Dehy supplement was fed to provide the same amount of CP/d as Mod-CP, and all supplements provided similar amounts of ME/d. Forage DMI was increased (P less than .05) by feeding Mod-CP and Dehy. Ruminal OM digestibility was 39% greater (P less than .05) for the Mod-CP and Dehy supplementations than for the Low-CP supplementation and control. Ruminal CP digestibility was negative for all treatments, and control (-326%) was less (P less than .05) than supplemented treatments (average -27%). Total tract OM digestibility was greatest (P less than .10) for steers fed Mod-CP and least for control steers; Low-CP and Dehy steers were intermediate. Total tract NDF digestibility tended (P = .15) to be less with Low-CP than with Mod-CP and Dehy. Duodenal N flow was greater (P less than .05) with Mod-CP and Dehy than with Low-CP and control. In summary, supplementation with Mod-CP increased forage intake, digestion, and duodenal N flow compared with Low-CP or control; however, the response was similar when Mod-CP and Dehy supplements were fed to provide equivalent amounts of CP and ME daily.  相似文献   

11.
Seven Holstein steers (340 kg) fitted with ruminal, duodenal and ileal cannulae were used to measure the influence of supplemental N source on digestion of dietary crude protein (CP) and on ruminal rates of protein degradation. Diets used were corn-based (isonitrogenous, 12% CP on a dry matter basis, and isocaloric, 80% total digestible nutrients) with urea, soybean meal (SBM), linseed meal (LSM) or corn gluten meal (CGM) as supplemental N. Ruminal ammonia N concentrations were higher (P less than .05) in steers fed LSM than in those fed CGM, but did not differ from those in steers fed urea or SBM (11.7, 6.7, 9.1 and 9.2 mg/100 ml, respectively). Due to the high degradability of urea, ruminal digestion of dietary CP was greater (P less than .05) in steers fed urea than in those fed CGM, but intermediate in steers fed SBM and LSM (58.4, 48.8, 53.1 and 53.9%, respectively). Flow of bacterial nonammonia N to the duodenum was highest (P less than .05) in steers fed SBM or LSM, intermediate (P less than .05) for urea and lowest (P less than .05) for CGM (86.8, 86.1, 76.3 and 65.9 g/d, respectively). Efficiency of bacterial protein synthesis was lowest in steers fed CGM and differed (P less than .05) from SBM (15.6 vs 21.8 g N/kg organic matter truly digested, respectively). Rate of ruminal digestion for SBM-CP differed (P less than .05) from that of CGM-CP but not from that of LSM-CP (17.70, 5.20 and 10.13%/h, respectively). The slow rate of ruminal degradability of CGM resulted in increased amounts of dietary protein reaching the intestinal tract but lower amounts of bacterial protein, thus intestinal protein supply was not appreciably altered.  相似文献   

12.
Eight multicannulated heifers (average BW 415 +/- 34 kg) were used in a replicated 4 x 4 Latin square to evaluate fluid milk processing wash water solids (WWS) as a dietary N source. Heifers were fed corn/cottonseed hull-based diets containing soybean meal (control, 0% WWS N) or WWS replacing soybean meal at 33, 67, or 100% of supplemental dietary N. Total tract and ruminal DM and OM digestibilities decreased linearly or cubically (P less than .05) as dietary WWS N increased. Total ruminal VFA concentration (P less than .05) and propionic acid molar proportion (P less than .10) were greater in heifers fed 0 vs 100% WWS N. Heifers fed 0% WWS N had the greatest (P less than .05) ruminal ammonia concentration at all sampling times. Dietary WWS did not affect (P greater than .10) ruminal pH, fluid dilution rate, fluid flow, fluid volume, or turnover time. Total tract N digestibility decreased quadratically (P less than .10) with increasing WWS N in the diet. Supplemental WWS N did not affect (P greater than .10) flow of duodenal ammonia N or bacterial N, or efficiency of microbial N synthesis. Diets containing WWS N resulted in a cubic increase (P less than .10) in duodenal flow of essential amino acids compared with 0% WWS N; however, there were no differences in small intestinal amino acid disappearance. Data indicate that WWS can replace 33% of the soybean meal N in a corn/cottonseed hull-based diet without decreasing ruminal fermentation, fluid digesta kinetics, microbial efficiency, or small intestinal amino acid utilization.  相似文献   

13.
Twelve steers (332 kg) were used in three simultaneous 4 x 3 incomplete Latin squares to evaluate effects of beet molasses (BEET), cane molasses (CANE), or concentrated separator by-product (CSB) as base ingredients in cooked molasses blocks on intake and digestion of prairie hay and ruminal characteristics. All steers had ad libitum access to prairie hay (5.9% CP and 69.4% NDF; DM basis). The four experimental treatments included a control (no supplement) and three cooked molasses blocks, based on BEET, CANE, or CSB, fed daily at .125% of BW (.42 kg/d as-fed, .13 kg/d CP). Forage OM, NDF, and N intakes; digestible OM, NDF, and N intakes; and total tract OM and N digestibilities (percentage of intake) were greater (P < .05) for steers fed cooked molasses blocks than for control steers. Total tract OM digestibility was greater (P < or = .06) for steers fed BEET blocks (54.0%) than for those fed CSB (52.1%) or CANE blocks (52.2%). Digestion of NDF was greatest (P < .05) for steers fed BEET blocks (51.9%) and tended to be greater (P < .07) for steers fed CANE (49.3%) or CSB blocks (49.3%) than for control steers (46.9%). Ruminal ammonia concentrations were greater (P < .05) for steers fed cooked molasses blocks (.89 mM) than for control steers (.21 mM); this was primarily due to increases to 4.6 mM at 2 h postfeeding for steers fed blocks. Concentrations of total VFA in ruminal fluid were greater (P < .05) for steers fed BEET (92.7 mM) and CSB (88.1 mM) blocks than for control steers (80.3 mM), whereas concentrations for steers fed CANE blocks were intermediate (85.4 mM). Steers supplemented with cooked molasses blocks had greater molar percentages of butyrate than did control steers, particularly shortly after feeding. In summary, supplementation with cooked molasses blocks increased forage intake and digestion. The three base ingredients elicited similar responses, although steers fed BEET had slightly greater OM and NDF digestibilities than those fed CANE or CSB.  相似文献   

14.
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   

15.
Four experiments were conducted to evaluate three crude protein (CP) sources (urea, U; soybean meal, SBM; corn gluten meal, CGM) in diets based on corn silage (high energy) or grass hay (low energy). In Exp. 1 and 2, growing steers were fed all combinations of energy and protein source at 10.5 or 12% CP. Steers fed high energy diets or 12% CP had improved (P less than .05) daily gains and feed:gain over 84 d. Protein source had no effect (P greater than .05) on performance except that steers fed U consumed more (P less than .05) feed than those fed CGM. Steers were fed experimental diets to a common weight and switched to an 85% concentrate diet for finishing. During finishing, steers fed low energy diets in the growing period consumed more (P less than .05) feed and had increased (P less than .05) feed:gain compared with those fed high energy diets. Growing lambs were fed the same diets as steers. At 10.5% CP, lambs fed high energy diets had higher (P less than .05) digestibilities of dry matter (DM), organic matter (OM), nitrogen (N) and fiber components, and retained more (P less than .05) N. For lambs on 12% CP, high energy diets had higher (P less than .05) DM and OM digestibilities and lower (P less than .05) N digestibilities. At 12% CP, energy level had no effect (P greater than .05) on N retained. Protein source had no effect (P greater than .05) on N retention. There appeared to be no advantage in supplementing with ruminally undegradable proteins, i.e. CGM, in these experiments.  相似文献   

16.
Three trials were conducted to evaluate finishing diets containing 67% steam-flaked corn (SFC), steamed-whole corn (SWC) or whole corn (WC). In a feeding trial, steers fed SWC consumed more (P less than .05) dry matter per day (7.6 kg) than those fed WC (7.0 kg) or SFC (6.7 kg). Average daily gain was greater (P less than .05) for steers fed SFC (1.33 kg) and SWC (1.31 kg) than for those fed WC (1.25 kg), and feed efficiency was better (P less than .05) for steers fed SFC (5.06 kg dry matter/kg gain) than for those fed WC (5.62) and SWC (5.79). Carcass characteristics were not different among the three groups. In a digestion trial, method of corn processing did not affect digestibility of dry matter and crude protein. Starch digestibility was greater (P less than .05) for SFC (99.1%) than for SWC (93.8%) and WC (93.0%). There were no differences in nitrogen (N) intake or fecal N among the three diets; however, urinary N was less (P less than .05) for SWC (19 g/d) than for SFC (27 g/d) and WC (32 g/d), and N retention was higher (P less than .05) for the SWC diet. In vitro dry matter digestibility of the SFC diet was higher (P less than .05) than for WC at 4 and 8 h of incubation and higher (P less than .05) than the SWC diet at 8, 12 and 24 h of incubation. In vitro gas production after 6 h was greater (P less than .05) for SFC than for SWC grain, which was greater (P less than .05) than WC.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

17.
Four experiments were conducted to determine the effect of adding corn gluten mean (CGM) or soybean meal (SBM) at 24- or 48-h intervals to diets based on corn stalks. In each experiment corn stalks was the primary diet ingredient fed to wethers or steers. Monensin was also fed to determine whether its effects on ruminal fermentation would improve the efficiency of N utilization under these conditions. Evaluation criteria included ruminal fermentation characteristics, DM intake and utilization, N balance in sheep, and steer feedlot performance. Ruminal ammonia nitrogen (NH3 N) concentrations measured over time were higher (P < .05) when diets contained SBM. Diet did not influence (P > .10) total VFA concentrations in ruminal fluid. Differences in diurnal shifts in ruminal NH3 N and total VFA due to protein source resulted in diet x hour interactions (P < .05). Dry matter intake response to protein source and frequency of supplement feeding was variable. Dry matter digestibility and nitrogen digestibility were not affected (P > .10) by protein source or feeding interval. The 48-h interval feeding of CGM was favorable compared with 24-h interval feeding (P < .05). The opposite response occurred with SBM, resulting in a diet x feeding interval interaction (P < .05). Nitrogen retention was greater (P < .05) when CGM was fed and with alternate day feeding. Diets that contained CGM supported higher (P < .05) ADG and gain/feed than diets that contained SBM when fed to steer calves. Alternate day feeding of supplements that contained monensin was detrimental to steer performance under the conditions of these experiments. Corn gluten meal is an effective substitute for SBM when alternate day protein supplementation is practiced.  相似文献   

18.
Feed intake, digestion and digesta characteristics of cattle fed bermudagrass (BG) or orchardgrass (OG) alone or with supplemental ground corn or barley were determined in two 6 x 6 latin squares with 2 x 3 factorial treatment arrangements. In Exp. 1, beef cows (Hereford, Angus and Hereford-Angus; 452 kg) cannulated in the rumen and duodenum were fed BG (7.9% CP, 79% NDF and 8.7% ADL) or OG (9.8% CP, 79% NDF and 7.2% ADL) hays at 1.2% of BW per day either alone or with added ground barley (.64% BW) or ground corn (.60% BW daily). The increase in microbial OM flow with corn was greater for OG than for BG; corn elevated microbial OM flow more than did barley with OG but less than with BG (forage type x grain source interaction; P less than .10). The increase in total tract OM digestion with grain was greater for BG than for OG (supplementation effect and forage type x supplementation interaction; P less than 05). In Exp. 2, Holstein steers (228 kg) were fed BG and OG hays ad libitum either alone or with addition of either 1.07% of BW per day of barley or 1.00% BW of corn. Total DM intake was 2.19, 3.03 and 2.82% BW for BG and 2.14, 2.80 and 2.52% BW for OG alone or with barley or corn supplements, respectively, being affected by forage type, grain supplementation, grain type and a forage type x grain supplementation interaction (P less than .05). Organic matter digested daily (g/d) was higher for OG than for BG, higher with than without grain and higher for barley than for corn (P less than .05).  相似文献   

19.
Effects of advancing forage maturity and drought-induced summer dormancy on site and extent of digestion and microbial protein synthesis in beef steers grazing native blue grama rangeland were evaluated in four sampling periods. Five steers (avg initial wt 227 kg) fitted with ruminal, duodenal and ileal cannulae and three steers cannulated at the esophagus freely grazed a 12-ha study pasture. Sampling periods lasted 11 d and started June 2, which was during the early growing season (EGS); June 22, during early summer dormancy (ESD); July 21, during late summer dormancy (LSD); and August 25, 1985, during the late growing season (LGS). Dietary N content was lower (P less than .05) in ESD and LSD than in EGS and LGS. Neutral detergent fiber (NDF) content was lower (P less than .05) in EGS than in other sampling periods. Ruminal organic matter (OM) digestion was lower (P less than .05) in ESD than in EGS, probably because of increased dietary NDF and lower N content. Ruminal OM digestion was greater (P less than .05) in LSD and LGS than in ESD because of increased fiber digestion. Neutral detergent fiber and acid detergent fiber (ADF) digestion occurring in the rumen was greater (P less than .05) in LSD and LGS than in EGS and ESD. Organic matter digestion in the small intestine and OM, NDF and ADF digestion in the hindgut were similar for all sampling periods. Over 90% of the fiber digestion occurred ruminally.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
Prairie hay supplemented with various amounts of corn and soybean meal was fed to steers in two experiments. Effects of supplementation on hay OM intake, digestion, and ruminal fermentation and kinetics were measured. A preliminary study was conducted to attain accurate values for OM intake and digestibility of prairie hay to be used in ration formulation using the NRC (1996) level 1 model. Ten steers (284 +/- 9 kg) given ad libitum access to chopped prairie hay (75% NDF, 6% CP) were supplemented with dry-rolled corn (0.75% of BW/d) plus soybean meal (0.25% of BW/d). Hay OM intake was 1.85% of BW and hay OM digestibility was 48%. Based on results from the preliminary study, eight ruminally cannulated beef steers (317 +/- 25 kg) received a sequence of eight different supplementation combinations (2 x 4 factorial arrangement of treatments). These supplements consisted of dry-rolled corn at either 0 or 0.75% of BW (DM basis) daily combined with one of four amounts of added soybean meal to provide between 0 and 1.3 g of degradable intake protein (DIP)/kg of BW. After supplements had been fed for 10 d, feces were collected for 4 d. Intake of hay and total OM increased quadratically (P < 0.01) in response to added DIP with or without supplemental corn. Hay OM digestibility increased quadratically (P = 0.03) as DIP was added when corn was fed in the supplement. Intake of digestible OM was greater (P < 0.01) with than without corn supplementation. Increasing DIP increased (P < 0.01) digestible OM intake regardless of whether corn was fed. Inadequate ruminally degraded protein in grain-based supplements decreased forage intake, digestibility, and energy intake of cattle fed low-quality prairie hay. Providing adequate supplemental DIP to meet total diet DIP needs seemed to overcome negative associative effects typically found from supplementing low-quality forages with large quantities of low-protein, high-starch feeds.  相似文献   

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