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1.
Seventy-two Holstein steers averaging 182 kg were assigned randomly to one of six treatment groups: 1) nonimplanted controls (C); 2) implanted with 36 mg of zeranol (Z); 3) implanted with 20 mg of estradiol benzoate and 200 mg of progesterone (EP); 4) implanted with 140 mg of trenbolone acetate (TBA); 5) implanted with 140 mg of trenbolone acetate plus 20 mg of estradiol benzoate and 200 mg of progesterone (TBA + EP); and 6) implanted with 140 mg of trenbolone acetate plus 36 mg of zeranol (TBA + Z). Each treatment group consisted of three replications of four animals per pen, which were implanted on d 0, 56, 112, and 168. Masculinity and muscling scores were assigned at 24 h preslaughter. Hide removal difficulty was scored by a plant supervisor. Quality and yield grade data were obtained at 24 h postmortem. Longissimus muscle (LM) steaks were removed and cooked for Warner-Bratzler shear (WBS) determinations and sensory panel (SP) evaluations. Over the entire feeding period (249 d), TBA + EP steers had higher (P less than .05) ADG than TBA + Z, TBA, and C steers. All treatments had higher (P less than .05) ADG than C, with the exception of TBA. The only feed efficiency differences were those following the 168-d implant time, when TBA steers were more (P less than .05) efficient than TBA + Z or C steers. The TBA + EP and TBA + Z steers were more (P less than .05) masculine and their hides were more (P less than .05) difficult to remove than those of EP and C steers. Carcass weights of TBA + EP steers were heavier (P less than .05) than those of TBA or C steers. The TBA + EP steers had larger (P less than .05) LM areas than Z, TBA, and C steers. Also, TBA + EP steers tended (P = .07) to have lower numerical yield grades than EP, Z, or C steers. Even though mean marbling scores and quality grades were similar (P greater than .05) among treatment groups, only 50% of TBA + EP carcasses graded low Choice or higher, compared with 100, 75, 82, 90, and 83% for C, TBA, Z, EP, and TBA + Z carcasses, respectively. The only meat palatability differences were that myofibrillar and overall tenderness scores tended to be lower (P = .07) for steaks from EP and TBA + Z than for steaks from Z and C groups.  相似文献   

2.
Our objectives were to evaluate the dose/payout pattern of trenbolone acetate (TBA) and estradiol-17β (E(2)) implants and feeding of zilpaterol hydrochloride (ZH) on performance and carcass characteristics of finishing beef steers. A randomized complete block design was used with a 3 × 2 factorial arrangement of treatments. British × Continental steers (n = 168; initial BW = 362 kg) were blocked by BW and allotted randomly to 42 pens (7 pens/treatment; 6 pens/block; 4 steers/pen). The main effects of treatment were implant [no implant (NI); Revalor-S (REV-S; 120 mg of TBA + 24 mg of E(2)); and Revalor-XS (REV-X; 200 mg of TBA + 40 mg of E(2))] and ZH (0 or 8.3 mg/kg of DM for 20 d with a 3-d withdrawal before slaughter). Blocks were split into 2 groups, and block groups were fed for either 153 or 174 d. No implant × ZH interactions were noted for cumulative performance data. Overall, shrunk final BW (567, 606, and 624 kg for NI, REV-S, and REV-X, respectively), ADG (1.25, 1.51, and 1.60 kg), and G:F (0.14, 0.16, and 0.17) increased (P < 0.05) as TBA and E(2) dose increased. Implanting increased (P < 0.05) DMI, but DMI did not differ (P > 0.10) between REV-S and REV-X (8.8 for NI vs. 9.4 kg/d for the 2 implants). From d 1 to 112 of the feeding period, implanting increased (P < 0.05) ADG and G:F, but REV-S and REV-X did not differ (P > 0.10). From d 112 to end, ADG increased by 19% (P < 0.05) and G:F was 18% greater (P < 0.05) for REV-X vs. REV-S. Carcass-adjusted final BW (29-kg difference), ADG (0.2-kg/d difference), and G:F (0.02 difference) were increased (P < 0.05) by ZH, but daily DMI was not affected by feeding ZH. Hot carcass weight was increased (P < 0.05) by ZH (19-kg difference) and implant, with REV-X resulting in the greatest response (HCW of 376 for NI vs. 404 and 419 kg for REV-S and REV-X, respectively; P < 0.05). An implant × ZH interaction (P = 0.05) occurred for dressing percent (DP). Without ZH, implanting increased DP, but DP did not differ (P > 0.10) between REV-X and REV-S. With ZH, REV-X increased (1.7%; P < 0.05) DP vs. NI and REV-S. Marbling score, 12th-rib fat, and KPH were not affected (P > 0.10) by implant or ZH. Overall, treatment increased steer performance and HCW in an additive fashion, suggesting different mechanisms of action for ZH and steroidal implants. In addition, a greater dose of TBA + E(2) and extended payout improved steer performance and HCW.  相似文献   

3.
Four experiments evaluated the effect of implant dose and release pattern on performance and carcass traits of crossbred beef steers. In Exp. 1, steers (4 to 7 pens/treatment; initial BW = 315 kg) were fed an average of 174 d. Treatments were 1) no implant (NI); 2) Revalor-S [120 mg of trenbolone acetate (TBA) and 24 mg of estradiol 17β (E(2)); REV-S]; 3) Revalor-IS followed by REV-S (cumulatively 200 mg of TBA and 40 mg of E(2); reimplanted at 68 to 74 d; REV-IS/S); and 4) Revalor-XS (200 mg of TBA and 40 mg of E(2); REV-X). Carcass-adjusted final BW was greater (P < 0.05) for REV-X and REV-IS/S than for REV-S (610, 609, and 598 kg, respectively). Daily DMI did not differ (P > 0.10) among the 3 implants, but carcass-adjusted G:F was greater (P < 0.05) for REV-X and REV-IS/S than for REV-S (0.197 and 0.195 vs. 0.188). Both HCW and LM area were greater (P < 0.05) for REV-X and REV-IS/S than for REV-S. Marbling scores were greatest (P < 0.05) for REV-S and least (P < 0.05) for REV-IS/S; REV-X was intermediate to NI and REV-IS/S. In Exp. 2, steers (10 pens/treatment; initial BW = 391 kg) were fed 131 d, with treatments of REV-S, REV-IS/S (reimplanted at 44 to 47 d), and REV-X. Carcass-adjusted final BW (598 kg), ADG (1.6 kg), DMI (9.4 kg), G:F (0.17), and HCW did not differ (P > 0.10) among treatments. The percentage of Choice was less (P < 0.05) and percentage of Select greater (P < 0.05) for REV-IS/S than for REV-S and REV-X. In Exp. 3, steers (10 pens/treatment; initial BW = 277 kg) were fed 197 d and received either REV-IS/S (reimplanted at 90 to 103 d) or REV-X. Carcass-adjusted final BW (625 vs. 633 kg) and ADG (1.81 vs. 1.76 kg) were greater (P < 0.05) for REV-X-implanted steers. Daily DMI did not differ, but G:F tended (P < 0.10) to be increased and HCW was greater (P < 0.05) for REV-X than for REV-IS/S. In Exp. 4, steers (8 pens/treatment; initial BW = 238 kg) were fed 243 d and received either REV-IS/S (reimplanted at 68 to 71 d) or REV-X. Carcass-adjusted final BW (612 kg), ADG (1.54 kg), DMI (7.55), and G:F (0.21) did not differ (P > 0.10) for REV-IS/S and REV-X-implanted steers. Carcass traits did not differ among implants, but the percentage of Choice carcasses was greater (P < 0.05) and percentage of Select was less (P < 0.05) for REV-X than for REV-IS/S. These data indicate that when TBA/E(2) dose is equal, the altered release rate of REV-X can improve performance and quality grade, but these effects depend on duration of the feeding period and timing of initial and terminal implants.  相似文献   

4.
The effects of an implant of 140 mg of trenbolone acetate and 28 mg of estradiol (TBA + E2) on performance and carcass composition were evaluated with 72 individually fed steers. Holstein (n = 24), Angus (n = 24), and Angus x Simmental (n = 24) steer calves were allocated by breed and implant treatment to either an individual feeding pen (n = 36) or an electronic feeding door in a group pen (three pens with 12 animals per pen). Intake and refusal of the 85% concentrate diet were recorded daily. Animals were slaughtered when ultrasonic attenuation values of the longissimus muscle at the 12th rib reached .55, which is correlated with low Choice marbling. At slaughter, complete carcass measurements were taken and the right side of each carcass was separated into boneless wholesale cuts. Implanting with TBA + E2 improved (P less than .01) daily gain and feed efficiency. Daily gain was increased 17, 26, and 21% in Holstein, Angus, and crossbred steers, respectively. The implant increased overall daily protein and fat accretion 23%. Carcass conformation and dressing percentage were not affected (P greater than .05) by TBA + E2 treatment. Implantation with TBA + E2 had little effect on yield of wholesale boneless cuts when expressed as a percentage of carcass weight but increased absolute weight as a small degree of marbling by 6 to 40 kg.  相似文献   

5.
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6.
Skeletal muscle protein degradation, measured by urinary N tau-methylhistidine excretion, and circulating concentrations of growth hormone (GH), insulin (INS), and cortisol (CT) were monitored in steers before and after implantation with estradiol-17 beta (E2; 24 mg) and trenbolone acetate (TBA; 300 mg). Yearling crossbred steers (n = 43) were randomly assigned to four treatment groups in a 2 x 2 factorial arrangement: nonimplanted controls (C); TBA; E2; and TBA plus E2 (TBA+E2). A subgroup (Block 1) of 16 steers was bled on d -12, 31, and 72 after implanting. Deposition of skeletal muscle protein was markedly increased (P less than .001) by E2 and TBA+E2 treatment. This response occurred mainly within the first 40 d after implantation and declined (P less than .001) in concert with decreasing (P less than .01) concentration of serum E2. Anabolic steroid treatment did not affect the rate of skeletal muscle protein breakdown. There was no apparent relationship between reduced serum CT concentration (linear effect; P less than .01) in TBA-treated steers and skeletal muscle protein degradation rate. Blood concentration and pulse activity of INS were not affected by anabolic steroid administration. Both TBA- and TBA+E2-implanted steers displayed a linear decrease (P less than .05) in serum GH concentration over time, which was similar to C. Lowered mean GH concentration resulted from a reduction (TBA main effect; P less than .05) in pulse amplitude of GH. Unlike TBA, TBA+E2, and C, only E2 maintained serum GH concentrations over time. Although increased muscle protein deposition was evident in TBA+E2-treated steers, an obvious causal relationship between this response and circulating GH, INS, and CT was not revealed. These results do not support the concept that combined androgenic agent and estrogen administration effectively reduce bovine muscle protein degradation by static modulation of circulating endogenous anabolic and antianabolic hormones.  相似文献   

7.
The dose-response relationship of the ionophore tetronasin was defined in growing-finishing cattle (84 heifers and 84 steers). Cattle were allotted by sex and weight replication (light and heavy) to 24 pens. Six dosages (D) of tetronasin (0, 3.7, 7.3, 11.0, 14.7 and 18.3 mg/kg, dry matter [DM] basis) were fed. Diets containing 40, 25 and 10% roughage were fed for 84, 56 and either 56 (heavy replication) or 91 d (light replication), respectively. Average starting weights were 242 and 270 kg and ending weights were 433 and 480 kg for heifers and steers, respectively. No interactions existed for ionophore with sex (P greater than .2) over the trial. Ionophore treatment did not affect overall average daily gain (.94 kg/d; P greater than .2). Daily DM intake (kg/d) decreased linearly as the level of tetronasin increased (8.4-.042D (dosage), r2 = .83, P less than .001). Gain efficiency (gain/feed, kg/100 kg DM) increased curvilinearly as ionophore dosage increased (11 + .16D - .0058D2, r2 = .77, P less than .001). Solving the first derivative indicated an optimum dose for gain efficiency improvement of 13.8 mg/kg. The gain efficiency response was greatest the first 84 d, less the next 56 d and minimal the last 56 or 91 d (20, 7 and 2% improvement for D = 14.7 mg/kg, respectively). Tetronasin was found to improve gain efficiency by about 10% over control at an optimum dosage of 13.8 mg/kg.  相似文献   

8.
Supplemental chromium for stressed and growing feeder calves.   总被引：19，自引：0，他引：19  
The effects of supplemental chromium (Cr) from high-Cr yeast were investigated with steer calves fed corn silage diets. One hundred eight Charolais-crossed calves, weighing 245 kg after marketing and transport, were allotted to one of four treatments during the initial 28-d stress period: control, .4 ppm of Cr in the diet, long-acting injectable oxytetracycline (LAOTC), and Cr + LAOTC. Those fed Cr received 4 mg of Cr/d for the first 3 d sprinkled onto a small amount of hay over the silage. Chromium without LAOTC increased (P less than .05) ADG by 30% (.61 vs .79 kg/d) and ADG/DMI by 27% (.123 vs .156). Oxytetracycline alone increased (P less than .05) ADG by 30% and DMI by 15%. Chromium had no effect on morbidity. However, LAOTC tended (P less than .14) to reduce morbidity (26.0 vs 14.0%) after its administration. After d 28, steers were processed. Two weeks later, they were rerandomized within Cr groups to urea-corn vs soybean meal supplementation of corn silage during a 70-d growing period. Level of Cr was reduced to .2 ppm. Jugular blood was collected from eight steers on each treatment on two occasions. Chromium had no effect on ADG or ADG/DMI. However, Cr decreased (P less than .05) serum cortisol (75.0 vs 55.6 nmol/L). Furthermore, Cr increased (P less than .05) serum immunoglobulin M and total immunoglobulins in calves fed diets with soybean meal but had no effect in calves with urea-corn supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
The dose response of melengestrol acetate (MGA) on ADG (kg/d) and gain efficiency (gain/DMI, g/kg) was estimated in beef steers fed a finishing diet under commercial feedlot conditions. Melengestrol acetate is not approved for use in steers as a feed additive. The study design was five blocks of four pens (each pen was assigned a dose of MGA) with 166 to 200 steers per pen. Melengestrol acetate was fed to steers at 0 (n = 899, five pens), 0.1 (n = 900, five pens), 0.2 (n = 899, five pens), and 0.4 (n = 900, five pens) mg of MGA/steer daily. Pens within a block were slaughtered on the same day. Blocks 1 through 5 were fed MGA for 123, 122, 116, 124, and 138 d, respectively. The experimental unit was a pen of steers, and blocking was based on source of steers. The ADG was 1.81, 1.85, 1.80, and 1.83 kg/d for steers fed 0, 0.1, 0.2, and 0.4 mg MGA per day, respectively. For ADG, the dose was significant, but neither linear nor quadratic effects were significant. Compared with steers of the control group, ADG was greater for steers fed 0.1 mg MGA (P < 0.01). Feed efficiencies were 170, 173, 171, and 172 g/kg for steers fed 0, 0.1, 0.2, and 0.4 mg MGA/d, respectively; however, no effects of dose (P = 0.19) or linear (P = 0.21) or quadratic (P > 0.60) effects were observed. There was no evidence for either positive or negative effects of MGA on DMI, hot carcass weight, dressing percent, quality grade, yield grade, back fat thickness, marbling score, longissimus muscle area, and incidence of dark cutter carcasses in response to feeding MGA to steers at doses of 0.1, 0.2, and 0.4 mg daily. The incidence of buller behavior (0.43 to 1.11%) was low and did not permit an accurate test of the clinical observations that feeding MGA to steers decreases the occurrence of buller steers. Melengestrol acetate fed to finishing beef steers produced small improvements in growth performance (ADG, 2.2%) at the 0.1 mg MGA dose, but none of the doses examined produced improvement in carcass quality or yield grade measurements.  相似文献   

10.
Hereford steers (290 +/- 6 kg of BW) were implanted (n = 4) with 140 mg of trenbolone acetate (TBA) and 28 mg of estradiol-17 beta (E2 beta) or nonimplanted (controls, n = 4). In Trial 1, effects of a single i.v. injection of 0, 20, 40, or 80 micrograms of a growth hormone-releasing factor (1-29 NH2) analogue (GRFa) on release of endogenous somatotropin (ST) were evaluated in a double 4 x 4 Latin square design. Plasma samples (n = 21) were obtained from -20 to 240 min after GRFa injection. Area under the ST response curve (AUC) increased (P = .009) in a dose-dependent manner (.2, 2.6, 3.6, 4.3 mg.min-1.mL-1, respectively). Mean ST concentration was not affected (P = .238) by implant but AUC was greater (P = .009) in implanted than in control steers. There was no interaction (P = .460) between dose of GRFa and presence of implant. In Trial 2, 80 micrograms of GRFa was administered at 12-h intervals to the same eight steers. Response of ST (AUC) to the first and last (13th) i.v. injection of GRFa was similar and not affected by implant. Before GRFa administration, plasma insulin-like growth factor I (IGF-I) concentrations were greater (P = .039) in implanted than in control steers (272 vs 164 ng/mL). Administration of GRFa increased plasma IGF-I (P = .0001), decreased plasma urea N (PUN) (P = .0001), and did not alter plasma glucose (P = .447) in both control and implanted steers. Data indicate that effects of GRFa and TBA/E2 beta on plasma IGF-I and PUN concentrations were additive in this study.  相似文献   

11.
Twenty crossbred yearling steers (421 kg) were used to evaluate the effects of implanting with trenbolone acetate (TBA; 120 mg), estradiol-17β (E(2); 25.7 mg), and a combination (120 mg of TBA and 24 mg of E(2)) on adipogenic and myogenic mRNA concentrations. Animals were blocked by BW and within each block were assigned to 1 of 4 treatments. Animals were housed and fed in individual pens with 5 animals per treatment. All animals were weighed weekly, and muscle biopsy samples were taken from the LM of each steer on d 0 (before implantation), 7, 14, and 28. Total RNA was isolated from each sample and real-time quantitative PCR was used to measure the quantity of C/EBPβ, PPARγ, stearoyl CoA desaturase (SCD), myogenin, and 3 isoforms of bovine myosin heavy chain (MHC) mRNA. Total BW gain from the 28-d period was adjusted to d 0 by use of covariant analysis, and steers in the implant groups tended (P = 0.09) to have increased BW gain compared with nonimplanted control steers. Analysis of the gene expression of MHC showed that neither implant nor day (P > 0.20) had a significant effect on the expression of type I or IIX MHC mRNA There was also no treatment effect (P > 0.20) on MHC-IIA and myogenin, but increasing days on feed increased (P = 0.05) the expression of MHC-IIA mRNA. Relative mRNA abundance of C/EBPβ, PPARγ, and SCD increased (P < 0.05) during days of feed but PPARγ decreased (P < 0.05) with the treatment of combined TBA/E(2) implant. Results of this study indicate that implanting with TBA, E(2), or both increased BW gain and decreased adipogenic gene expression of finishing steers without significantly affecting the concentration of type I, IIA, or IIX MHC mRNA. Increasing days on feed increased both MHC-IIA and adipogenic gene expression in bovine skeletal muscle biopsy samples. We conclude that administration of steroidal implants had no effect on the proportion of the 3 MHC mRNA isoforms but decreased C/EBPβ, PPARγ, and SCD mRNA in bovine skeletal muscle.  相似文献   

12.
A 5-yr study was conducted involving the placement of yearling steers on feed at 2-mo intervals under three different housing systems. A total of 3,571 steers (180 pens) initially averaging 318 kg was used. Evaluations were made for DM intake, ADG, feed efficiency (FE), carcass quality (QG), and yield grades (YG). Cattle were assigned to either an open lot with overhead shelter (S), an open lot without overhead shelter (NS), or an open-front confinement building (C). Each treatment consisted of two lots of 20 steers each per interval per trial. Corn grain provided 85% of the energy; the remainder was supplied by corn silage and protein supplement. Cattle were fed 140 to 180 d to achieve an average slaughter weight of 500 kg. The main effects of year (Y), month (M), and housing (H) affected DM intake, ADG, FE, and final live weight (P less than .01). The interactions for Y x M, M x H and Y x M x H affected ADG (P less than .05). Month and H affected hot carcass weight (P less than .01). Year affected YG, and year and month affected QG (P less than .01). Month effects on DM intake and ADG indicated that cattle started in May had the highest intake and ADG (P less than .05) and that cattle started in November had the lowest (P less than .05) DMI and ADG. Month effects on FE indicated that cattle were most efficient when placed on feed during March, May, and July (5.82, 5.72, and 5.66 kg DM/kg gain; P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
Two commercial feedlot experiments and a metabolism study were conducted to evaluate the effects of monensin concentrations and bunk management strategies on performance, feed intake, and ruminal metabolism. In the feedlot experiments, 1,793 and 1,615 steers were used in Exp. 1 and 2, respectively, in 18 pens for each experiment (six pens/treatment). Three treatments were evaluated: 1) ad libitum bunk management with 28.6 mg/kg monensin and clean bunk management strategies with either 2) 28.6 or 3) 36.3 mg/kg monensin. In both experiments, 54 to 59% of the clean bunk pens were clean at targeted clean time, or 2200, compared with 24 to 28% of the ad libitum pens. However, only 13% of the pens were clean by 2000 in Exp. 1 (summer), whereas 44% of the pens in Exp. 2 (winter) were clean by 2000. In Exp. 1, bunk management and monensin concentration did not affect carcass-adjusted performance. In Exp. 2, steers fed ad libitum had greater DMI (P < 0.01) and carcass-adjusted ADG (P < 0.01) but feed efficiency (P > 0.13) similar to that of clean bunk-fed steers. Monensin concentration had no effect on carcass-adjusted performance (P > 0.20) in either experiment. A metabolism experiment was conducted with eight fistulated steers in a replicated 4 x 4 Latin square acidosis challenge experiment. An acidosis challenge was imposed by feeding 125% of the previous day's DMI, 4 h later than normal. Treatments consisted of monensin concentrations (mg/kg) of 0, 36.7, 48.9, or 36.7 until challenged and switched to 48.9 on the challenge day and 4 d following. Each replicate of the Latin square was managed with separate bunk management strategies (clean bunk or ad libitum). Feeding any concentration of monensin increased number of meals and decreased DMI rate (%/h) (P < 0.12) for the 4 d following the acidosis challenge. Meal size, pH change, and pH variance were lower (P < 0.10) for steers fed monensin with clean bunk management. However, no monensin effect was observed for steers fed ad libitum. Bunk management strategy has the potential to decrease DMI and ADG when steers managed on a clean bunk program are restricted relative to traditional, ad libitum bunk programs. Monensin helps control intake patterns for individuals, but increasing concentration above currently approved levels in this study seemed to have little effect.  相似文献   

14.
In three experiments the interrelationship between dietary CP and recombinant porcine somatotropin (rpSt, i.m. daily) on ADG, feed efficiency (F/G) and carcass traits was examined in crossbred Yorkshire gilts and barrows given ad libitum access to their diets during the finishing period (55 to 110 kg BW). Pigs, blocked by BW and gender, were assigned (four/pen) within block. In Exp. 1, 140 pigs were assigned two/gender per pen to each of five pens/block and received a diet of either 12%, 18% or 24% CP (n = 2, 1 and 2 pens/block, respectively). Pigs received rpSt, either 0 or 120 micrograms/kg BW (12% and 24% CP groups) or 60 micrograms/kg BW (18% CP group). When CP was 12%, rpSt decreased ADG and increased F/G (P less than .05), whereas when CP was 18% or 24%, rpSt increased ADG and lowered F/G (P less than .05). Backfat thickness was reduced (P less than .05) by rpSt regardless of CP. In Exp. 2, 120 pigs were assigned two/gender per pen to each of five pens/block and received a diet of 24% CP. Either 0, 15, 30, 60 or 120 micrograms of rpSt/kg BW was administered to each pig. All doses of rpSt increased ADG, lowered F/G and decreased backfat thickness compared with measurements for control pigs (P less than .05). In Exp. 3, 140 pigs were assigned two/gender per pen to each of seven pens/block and received a diet of either 14%, 18% or 24% CP (n = 3, 2 and 2 pens/block, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

15.
One hundred sixty pigs were used in a 2 x 2 factorial design to compare the performance response to daily injection of porcine somatotropin (PST); (0 or 2 mg/d) in animals fed a 14% CP corn-soy diet (control, C) to those fed a diet with 10% added fat (F) and calorie:protein and lysine:protein ratios similar to that of the C diet. Treatments, assigned randomly to 20 pens (n = 5/treatment) of eight pigs each, were initiated at 90 kg body weight and continued for 28 d. Responses to PST and dietary fat were typical. These include improved gain and feed efficiency and decreased feed intake. The effects of dietary fat on intake and efficiency were accounted for largely by the difference in energy density of these diets. Across diets, PST treatment resulted in a 13% improvement in ADG (P less than .001), a 13% decrease in feed intake (P less than .0001) and a 22% improvement in efficiency (P less than .0001). Of particular interest were the additive (PST x diet interaction, P less than .2) effects of PST and dietary fat on gain in these animals. Pigs treated with PST that were fed the F diet had greater rates of gain than did PST-treated pigs fed the C diet (P less than .05). Treatment with PST increased ADG by 9% in pigs consuming the C diet vs 16% in pigs fed the F diet. Similarly, dietary fat resulted in 4 and 11% increases in ADG in pigs treated with 0 or 2 mg of PST/d.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

16.
The objectives of this research were to determine the interaction of monensin and haylage supplementation for steers fed 60% dried distillers grains (DDGS) on 1) mineral status, performance, and carcass characteristics, and on 2) ruminal pH, H(2)S, and short-chain fatty acid concentrations. In Exp. 1, Angus-cross steers (n=168; BW=277 ± 67 kg) were blocked by BW and allotted in a 2 × 2 factorial arrangement of treatments to 24 pens. Dietary treatments were 1) 0 mg of monensin/kg of diet + 0% haylage, 2) 33 mg of monensin/kg of diet + 0% haylage, 3) 0 mg of monensin/kg of diet + 10% haylage, and 4) 33 mg of monensin/kg of diet + 10% haylage. The remainder of the diet was 60% DDGS, 10% corn silage, 15% supplement, and corn (either 5 or 15%) on a DM basis. When supplemented with 0 mg of monensin/kg of diet, added haylage increased ADG by 5.7%, whereas when supplemented with 33 mg of monensin/kg of diet, added haylage increased ADG by 13% (P < 0.01). No interactions of monensin and haylage were observed for DMI or G:F (P ≥ 0.36). Haylage inclusion increased (P < 0.01) DMI and decreased (P < 0.01) G:F. No interactions (P > 0.05) on plasma mineral concentrations were observed; however, over time, plasma Cu concentrations decreased (P < 0.01), whereas plasma ceruloplasmin and S concentrations increased (P < 0.01). There were no treatment effects (P ≥ 0.08) on carcass characteristics. Cattle fed the 60% DDGS diets benefitted from increased dietary forage, and the effects of monensin and forage were additive for ADG and final BW. In Exp. 2, ruminally fistulated steers (n=8; BW = 346 ± 34 kg) were used in a replicated 4 × 4 Latin square design and were randomly assigned to the diets used in Exp. 1. Haylage inclusion increased ruminal pH from 1.5 through 12 h postfeeding, and the effects of monensin supplementation were additive (P < 0.05). From 1.5 through 9 h postfeeding, steers fed 33 mg of monensin/kg of diet tended to have reduced (P ≤ 0.10) concentrations of H(2)S when compared with steers fed 0 mg of monensin/kg of diet. Acetate:propionate ratios at 6 h postfeeding were 0.94, 0.93, 1.29, and 1.35 for diets 1 to 4, respectively (P < 0.01); total lactate was decreased regardless of treatment (range: 0.94 to 1.42 μmol/mL). Sulfuric acid in DDGS, not ruminal short-chain fatty acids, may be responsible for the low rumen pH observed and may influence the maximum inclusion of DDGS in cattle diets. Monensin supplementation decreased H(2)S concentration and may decrease the risk of polioencephalomalacia for cattle fed high-DDGS diets.  相似文献   

17.
A winter grazing/feedlot performance experiment repeated over 2 yr (Exp. 1) and a metabolism experiment (Exp. 2) were conducted to evaluate effects of grazing dormant native range or irrigated winter wheat pasture on subsequent intake, feedlot performance, carcass characteristics, total-tract digestion of nutrients, and ruminal digesta kinetics in beef cattle. In Exp. 1, 30 (yr 1) or 67 (yr 2) English crossbred steers that had previously grazed native range (n = 38) or winter wheat (n = 59) for approximately 180 d were allotted randomly within previous treatment to feedlot pens (yr 1 native range = three pens [seven steers/pen], winter wheat = two pens [eight steers/pen]; yr 2 native range = three pens [eight steers/pen], winter wheat = four pens [10 or 11 steers/pen]). As expected, winter wheat steers had greater (P < 0.01) ADG while grazing than did native range steers. In contrast, feedlot ADG and gain efficiency were greater (P < 0.02) for native range steers than for winter wheat steers. Hot carcass weight, longissimus muscle area, and marbling score were greater (P < 0.01) for winter wheat steers than for native range steers. In contrast, 12th-rib fat depth (P < 0.64) and yield grade (P < 0.77) did not differ among treatments. In Exp. 2, eight ruminally cannulated steers that had previously grazed winter wheat (n = 4; initial BW = 407 +/- 12 kg) or native range (n = 4; initial BW = 293 +/- 23 kg) were used to determine intake, digesta kinetics, and total-tract digestion while being adapted to a 90% concentrate diet. The adaptation and diets used in Exp. 2 were consistent with those used in Exp. 1 and consisted of 70, 75, 80, and 85% concentrate diets, each fed for 5 d. As was similar for intact steers, restricted growth of cannulated native range steers during the winter grazing phase resulted in greater (P < 0.001) DMI (% of BW) and ADG (P < 0.04) compared with winter wheat steers. In addition, ruminal fill (P < 0.01) and total-tract OM digestibility (P < 0.02) were greater for native range than for winter wheat steers across the adaptation period. Greater digestibility by native range steers early in the finishing period might account for some of the compensatory gain response. Although greater performance was achieved by native range steers in the feedlot, grazing winter wheat before finishing resulted in fewer days on feed, increased hot carcass weight, and improved carcass merit.  相似文献   

18.
Two experiments were conducted to investigate the effects of proportion of dietary corn silage during periods of feed restriction on performance of steers. In Exp. 1, Simmental x Angus steer calves (n = 107; initial BW = 273 +/- 3.8 kg) were allotted to 12 pens with eight or nine steers/pen and four pens/treatment. Periods of growth were 273 to 366 kg BW (Period 1), 367 to 501 kg BW (Period 2), and 502 to 564 kg BW (Period 3). In two of the dietary regimens, steers were given ad libitum access to feed throughout the experiment and were fed either a 15% corn silage diet in each period or an 85, 50, and 15% corn silage diet in Periods 1, 2, and 3; respectively. In the third feeding regimen, a programmed intake feeding regimen was used. Steers were fed a 15% corn silage diet in each period. However, feed intake was restricted to achieve a predicted gain of 1.13 kg/d in Period 1 and 1.36 kg/d in Period 2, and feed was offered for ad libitum consumption in Period 3. For the entire experiment, ADG was similar (P = 0.41) among treatments and feed efficiency was lower (P < 0.10) for steers in the corn silage regimen than for steers in the programmed intake and ad libitum regimens. In Exp. 2, Simmental x Angus steer calves (n = 106; initial BW = 233 +/- 2 kg) were allotted by BW to 12 pens (three pens/treatment) and fed in three periods similar to those described in Exp. 1. Four feeding regimens were investigated: 1) AL; steers were offered a 15% corn silage diet for ad libitum consumption in all three periods; 2) PI; DMI was programmed to achieve gains as described in Exp. 1; 3) CS-HLL; programmed intake as described above except diets contained 85, 15, and 15% corn silage in Periods 1, 2, and 3, respectively; and 4) CS-HIL; same feeding regimens as CS-HLL, except diets contained 85, 50, and 15% corn silage in Periods 1, 2, and 3, respectively. Steers were given ad libitum access to feed in Period 3. Overall ADG was lower (P < 0.05) for steers in the CS-HLL and CS-HIL feeding regimens than for steers in the AL and PI regimens; feed efficiency was greatest for steers in the PI regimen. Few effects of feeding regimen on carcass characteristics were observed.  相似文献   

19.
Two experiments were conducted to determine the effect of degree of corn processing on urinary ammonia and urea N concentrations, serum metabolite and insulin concentrations, and feedlot performance of steers. Corn was processed by either dry rolling to .54 kg/L bulk density (DR42; 42 lb/bushel) or steam flaking to a bulk density of .36 or .26 kg/L (28 [SF28] and 20 [SF20] lb/bushel, respectively). Degrees of processing were selected to generate final products with 25, 50, or 75% enzymatically available starch. Available starch, expressed as a percentage of total starch for DR42, SF28, and SF20, averaged 24.5, 56.4, and 81.1% in Exp. 1 and 22.4, 60.1, and 80.1% in Exp. 2. In Exp. 1, 29 steers were housed in individual outdoor pens and adapted to a 90% concentrate diet over 21 d. Whole blood and urine were collected before feeding and at 4 and 8 h after feeding on d 0, 7, 14, 21, 28, 84, and 140. Daily DMI decreased linearly (P < .03) as degree of processing increased, whereas water intake did not differ (P > .42) among treatments. Average daily gain, ADG:DMI, and hot carcass weight responded quadratically (P < .04) to an increasing degree of processing. Urinary ammonia and urea N concentrations were not influenced (P > .30) by degree of processing. Whole blood packed cell volume, serum glucose, creatinine, D(-)-lactate, L(+)-lactate, and lactate dehydrogenase activity did not differ (P > .15) among treatments. For insulin data, ME intake on the day of sample collection was evaluated as a covariate. On d 28, serum insulin (2.49, 2.95, and 1.80+/-.33 ng/mL) responded quadratically (P = .04) as degree of processing increased. Serum insulin did not differ (P = .52) on d 84, whereas insulin (5.77, 7.51, and 4.12+/-.98 ng/mL) responded quadratically (P = .02) on d 140. In Exp. 2,216 steers were blocked by BW into two blocks (18 pens; 12 steers/pen) and assigned to the same treatments used in Exp. 1. Daily DMI and carcass weight responded quadratically (P < .05), whereas ADG and ADG:DMI increased linearly (P < .04) with increasing degree of processing. Results suggest that the degree of corn processing influences serum insulin concentrations of feedlot steers; however, serum metabolites, urinary nitrogen composition, and carcass characteristics were generally not affected by degree of corn processing.  相似文献   

20.
Although Brahman crosses constitute a large portion of US beef cattle, little information is available on their response to diverse feed resources compared with Bos taurus steers. Thus, the objectives were to evaluate genotype and diet effects on steer performance during the growing period and subsequent response to a high grain diet during the finishing period. Fifty-one steers [0 (15), 1/4 (20), 1/2 (7), and 3/4 Brahman (9), with the remaining proportion being MARC III] were allotted to 8 pens. Beginning on December 2, steers were individually fed chopped bromegrass hay (n = 26; DM = 85%, CP = 9.5%, ME = 2.19 Mcal/kg) or a corn silage-based diet (n = 25; DM = 51%, CP = 11.9%, ME = 2.75 Mcal/kg) for 119 d. All steers were then fed a high corn diet (DM = 79%, CP = 11.7%, ME = 3.08 Mcal/kg) to a target BW of 560 kg (176 d). Data were analyzed by ANOVA, with genotype, growing diet, and the 2-way interaction included. The interaction was not significant (P > 0.25). The MARC III and 1/2 Brahman steers weighed more (P < 0.01) than 1/4 or 3/4 Brahman steers initially and at the end of the growing period. Weight of bromegrass-fed (325 kg) steers was less than that of corn silage-fed (384 kg) steers at the end of the growing period. Steer ADG and intake of DM, CP, and ME were less (P = 0.087 to 0.001) for 1/4 and 3/4 Brahman than for 0 or 1/2 Brahman steers during growing, finishing, and total, but efficiency of gain did not differ (P > 0.10). Carcass weight, marbling score, quality grade (P < 0.05), and kidney fat (P = 0.06) differed among genotypes. Daily DMI (6.91 vs. 7.06 kg) was similar, but CP (0.66 vs. 0.84 kg) and ME (15.2 vs. 19.4 Mcal) intake of bromegrass fed was less (P = 0.001) than those of corn silage-fed steers. Values for DMI/gain (22.3 vs. 7.43 kg/kg), CP intake/gain (2.13 vs. 0.88 kg/kg), and ME intake/gain (48.8 vs. 20.4 Mcal/kg) were greater (P < 0.001) in bromegrass-fed than corn silage-fed steers. Over the total study, ADG was lower (0.96 vs. 1.01 kg), and DMI (7.82 vs. 7.19 kg), DMI/gain (8.21 vs. 7.10 kg/kg), and ME intake/gain (22.6 vs. 20.9 Mcal/kg) were greater (P < 0.05) in bromegrass-fed than in corn silage-fed steers. Carcass weight, dressing percent, adjusted backfat, and yield grade (P < 0.05) were greater for corn silage-fed than for bromegrass-fed steers. Feed intake and performance, but not efficiency, differed among these genotypes. Compensatory performance during finishing was insufficient to overcome reduced performance during the growing period.  相似文献   

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