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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   
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The records of all dogs and cats receiving total parenteral nutrition (TPN) over a 43-month period were examined retrospectively. Dextrose, amino acids, lipids, electrolytes, and vitamins were administered by central venous catheter according to published nutrient recommendations; 72 dogs and 12 cats were studied, accounting for 380 patient days of TPN. Duration of TPN administration was 1–14 days with a mean of 4.5 days. Most animals required TPN because of gastrointestinal dysfunction, and more than half of them gained weight during TPN administration. Mechanical complications were frequent. Metabolic complications, especially lipid and glucose intolerance, were also commonly seen. Septic complications were the least frequently encountered, but resulted in patient morbidity and may have contributed to mortality. Most animals receiving TPN were returned to enteral nutrition and discharged. For critically ill animals unable to tolerate enteral alimentation, TPN can be supportive therapy in the treatment of the primary disease.  相似文献   
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There is a need to improve the lean tissue content of ruminant animals destined for meat production. Muscle fiber number is set during fetal development. The effect of undernutrition of pregnant ewes on subsequent muscle fiber characteristics of their offspring was investigated. The trial involved 32 pregnant ewes carrying twins. The ewes were allocated randomly to one of four groups: three different treatment groups (n = 8) and a control group (n = 8). The diet of the treatment groups was dropped to 50% of their daily requirement to support the ewe and allow for conceptus growth for varying periods before being returned to 100% of their daily requirement until term. Group d 30-70 ewes were fed 100% of their daily requirement until d 30, the diet was then decreased to 50% until d 70; it was then returned to 100% of their daily requirement until term. Group d 55-95 ewes were similarly restricted from d 55 through 95, and Group d 85-115 ewes were restricted from d 85 through 115. The control group was fed 100% of their daily requirement to support the ewe and allow for conceptus growth throughout gestation. After parturition, the lactating ewes were fed a normal commercial diet. On d 14 (after parturition), the lambs were slaughtered and the LM, semitendinosus (ST), and vastus lateralis (VL) were dissected and snap frozen. The immunochemical determination of myosin heavy-chain slow (MHC-slow) and myosin heavy-chain fast (MHC-fast) proteins was measured by immunoprobing of Western blots. The number of fast and slow fibers and the diameter of these fibers also were measured in each muscle sample by histochemical techniques. Decreased maternal nutrition before fiber formation (d 30 through 70) was observed to change the muscle characteristics of the newborn lambs. These lambs had significantly fewer fast fibers (P < 0.001) and significantly more slow fibers (P < 0.001) in both the LM and VL compared with the other groups. Maternal nutrient restriction at the other periods had no effect on the number of muscle fibers in the newborn lambs; however, a decrease (LM, P < 0.05; VL, P < 0.01; ST, P = 0.08) in muscle weight was observed in the lambs born to the ewes restricted between d 85 and 115 of gestation compared with the other groups. This study has shown that decreased maternal diet before muscle fiber formation will alter the muscle fiber development in the fetus.  相似文献   
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To study the inverse relationship between feed level and concentrations of peripheral plasma progesterone, 36 ovariectomised ewes were fed rations at levels calculated to maintain liveweight (M). On the seventh day, the ewes were given an intravenous infusion of progesterone and the metabolic clearance rate (MCR) was calculated. The ewes were then randomly allotted to receive either , M or 2M rations for seven days at which time the infusion and blood sampling schedules were repeated. The mean (SE) MCR of infused progesterone in ovariectomised ewes fed either , M or 2M rations for seven days was 7·1 (0·59), 9·9 (1·64 and 13·0 (1·19) litre h−1 kg−1 of liveweight, respectively. Differences in MCR of progesterone between ewes fed and 2M rations were significant (P<0·05). The inverse relationship between level of feed intake and plasma progesterone concentration was attributed to differences in clearance rate of progesterone rather than to changes in the entry rate of the hormone into the blood.  相似文献   
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This study examined the effectiveness of a strategic dosing scheme in lowering the incidence of fasciolosis on a mixed dry-stock farm and in maintaining the reduced incidence following a reduction in dosing intensity. Two neighbouring farms with a history of chronic fluke disease were selected, the strategic dosing scheme being implemented on one (the trial farm) while the other (the control farm) continued to treat according to its normal practice. The strategic dosing scheme was designed to suppress the faecal egg output of Fasciola hepatica at critical times of the year in order to limit infection of the intermediate host snail population and thus reduce the subsequent contamination of the pasture with metacercariae. On the trial farm cattle and sheep were treated three times per year for the first 2 years at approximately 8 week intervals, starting in March of each year. A fourth treatment was given when the cattle were housed and out-wintered sheep received an additional treatment in January. In Years 3 and 4 the dosing intensity was reduced. By the end of Year 2, data from faecal egg counts, tracer-sheep fluke burdens and snail infection levels indicated that the treatment strategy had succeeded in suppressing the fluke population and eliminating the occurrence of clinical fasciolosis. The decrease in dosing intensity in Years 3 and 4 maintained both stock and snail infections at low levels and there was no re-emergence of the disease.  相似文献   
20.
Metabolite profiling has been carried out to assess the compositional changes occurring in potato tubers after genetic modifications have been made to different metabolic pathways. Most major features in the (1)H NMR and HPLC-UV profiles of tuber extracts have been assigned. About 40 GM lines and controls belonging to 4 groups of samples (derived from cv. Record or cv. Desirée and modified in primary carbon metabolism, starch synthesis, glycoprotein processing, or polyamine/ethylene metabolism) were analyzed. Differences were assessed at the level of whole profiles (by PCA) or individual compounds (by ANOVA). The most obvious differences seen in both NMR and HPLC-UV profiles were between the two varieties. There were also significant differences between two of the four Desirée GM lines with modified polyamine metabolism and their controls. Compounds notably affected were proline, trigonelline, and numerous phenolics. However, that modification gave rise to a very abnormal phenotype. Certain lines from the other groups had several compounds present in significantly higher or lower amounts compared to the control, but the differences in mean values amounted to no more than a 2-3-fold change: in the context of variability in the whole data set, such changes did not appear to be important.  相似文献   
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