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R L Reid

Publications and source records attributed to R L Reid.

At least 37 records · Page 2Linked to original sources
PubMed1995

Treatment with 5-aminolevulinic acid and photoactivating light causes destruction of preimplantation mouse embryos.

OBJECTIVE: To evaluate the direct effect of photodynamic treatment with 5-aminolevulinic acid (ALA) on preimplantation mouse embryos in an in vitro setting. DESIGN: Preimplantation mouse embryos were incubated with or without ALA for 5 hours and followed immediately by light exposure for 0, 5, or 15 minutes. Comparison of the viability and blastocyst formation was made among different treatment groups. SETTING: A conventional laboratory setting with embyro culture facilities. INTERVENTIONS: Female CD1 mice were superovulated with pregnant mare serum gonadotropin and hCG before mating. Four-and eight-cell embryos and compacted morulae were flushed from the oviducts and incubated with 0, 0.1, 0.5, 1.0, or 5.0 mM ALA for 5 hours. Embryos subsequently were exposed to photoactivating light for 0, 5, or 15 minutes. MAIN OUTCOME MEASURES: Microscopic assessment of embryos quality at 12 hours and determination of the percentage of embryos progressing to the blastocyst stage at 36 or 60 hours. RESULTS: Incubation of embryos with 0.1, 0.5, 1.0, 5.0 mM ALA without light resulted in 87.3% +/- 1.6%, 84.9% +/- 3.4%, 81.4% +/- 1.8%, and 82.8% +/- 4.7% of the embryos developing to blastocysts, respectively. In the absence of ALA, light exposure for 0, 5, or 15 minutes resulted in 93.8% +/- 2.3%, 92.3% +/- 2.2%, and 85.9% +/- 1.7% blastocyst formation. Combining treatment of ALA at the same concentrations with light resulted in 33.3% +/- 2.1%, 0.7% +/- 0.9%, 0%, 0% (5-minute light), 13.3% +/- 1.0%, 0%, 1.6% +/- 1.3%, 0% (15-minute light) blastocyst formation, respectively. When gross morphology was used to assess embryo viability at 12 hours, similar results were observed. Measurement of the fluorescent spectrum of embryos incubated with ALA indicated that protoporphyrin IX had been formed. CONCLUSION: Photodynamic ablation of mouse embryos was achieved with ALA under in vitro conditions. These results indicate that preimplantation mouse embryos are capable of converting ALA to the photosensitizer, protoporphyrin IX, and are susceptible to subsequent photoablation. A photodynamic effect on the embryo may be important to the successful application of this technique to the treatment of human ectopic pregnancy.

Aminolevulinic Acid↗
PubMed1994

Photodynamic ablation of early pregnancy in the rat with 5-aminolevulinic acid: a potential new therapy for tubal ectopic pregnancy in the human.

OBJECTIVE: To determine whether systemic 5-aminolevulinic acid (ALA) could produce photosensitization and photodynamic ablation of early pregnancy in the rat. SETTING: A conventional laboratory setting. PATIENTS: Female Sprague-Dawley rats, weighing 220 to 275 g at the time of breeding. INTERVENTIONS: Rats at 10 days of gestation were injected IV with saline, 20 or 200 mg/kg ALA. Three hours later, the abdominal cavity was opened to record the number of fetuses in both uterine horns. One or both uterine horns were exposed to photoactivating light at 630 nm for 0, 5, 15, or 30 minutes. MAIN OUTCOME MEASURES: Mean fetal survival rate was determined 7 days after treatment. RESULTS: The mean +/- SEM fetal survival rates in groups (n = 6) treated with saline, 20 or 200 mg/kg ALA followed by 30-minute light exposure were 90.8% +/- 2.8%, 16.0% +/- 4.9%, and 0%, respectively. The mean +/- SEM fetal survival rates in groups (n = 6) treated with 200 mg/kg ALA followed by 0-, 5-, 15-, or 30-minute light exposure were 71.3% +/- 11.8%, 8.9% +/- 6.2%, 0.9% +/- 1.3%, and 0%, respectively. CONCLUSIONS: We conclude that systemic ALA followed by transmural exposure to photoactivating light (630 nm) results in resorption of early pregnancies in the rat. This approach could potentially be developed as a new treatment for human ectopic pregnancy.

Aminolevulinic Acid↗
PubMed1994

Involvement of transcription factor YB-1 in human T-cell lymphotropic virus type I basal gene expression.

Sequences which control basal human T-cell lymphotropic virus type I (HTLV-I) transcription likely play an important role in initiation and maintenance of virus replication. We previously identified and analyzed a 45-nucleotide sequence (downstream regulatory element 1 [DRE 1]), +195 to +240, at the boundary of the R/U5 region of the long terminal repeat which is required for HTLV-I basal transcription. We identified a protein, p37, which specifically bound to DRE 1. An affinity column fraction, containing p37, stimulated HTLV-I transcription approximately 12-fold in vitro. We now report the identification of a cDNA clone (15B-7), from a Jurkat expression library, that binds specifically to the DRE 1 regulatory sequence. Binding of the cDNA fusion protein, similarly to the results obtained with purified Jurkat protein, was decreased by introduction of site-specific mutations in the DRE 1 regulatory sequence. In vitro transcription and translation of 15B-7 cDNA produced a fusion protein which bound specifically to the HTLV-I +195 to +240 oligonucleotide. The partial cDNA encodes a protein which is homologous to the C-terminal 196 amino acids of the 36-kDa transcription factor, YB-1. Cotransfection of a YB-1 expression plasmid increases HTLV-I basal transcription approximately 14-fold in Jurkat T lymphocytes. On the basis of the molecular weight, DNA-binding characteristics, and in vivo transactivation activity, we suggest that the previously identified DRE 1-binding protein, p37, is YB-1.

Amino Acid Sequence↗
PubMed1994

Vasopressin mediates hypoglycemia-induced inhibition of luteinizing hormone secretion in the ovariectomized rhesus monkey.

The objective of the present study was to examine the role of vasopressin in the regulation of LH secretion in the rhesus monkey. The effect of vasopressin administration on basal LH secretion and vasopressin antagonism on stress-induced inhibition of LH secretion were examined. Intracerebroventricular (i.c.v.) infusion of vasopressin (20 micrograms/h) to chair restrained ovariectomized rhesus monkeys (n = 5) decreased the area under the LH curve by -51.61 +/- 13.73 ng/ml/h compared to -8.35 +/- 7.11 ng/ml/h following infusion of artificial CSF (aCSF; p = 0.021). This effect was independent of any change in mean arterial pressure. Subsequently, the role of vasopressin in hypoglycemia-induced suppression of LH was examined. Administration of insulin (1 U/kg BW) to chair-restrained ovariectomized rhesus monkeys decreased the area under the LH curve by -60.88 +/- 19.77 ng/ml/h. The decrease in LH was significantly different from that observed in aCSF-infused euglycemic controls which exhibited a slight decrease in LH (-8.35 +/- 7.11 ng/ml/h; p = 0.036). In contrast, the area under the LH curve was increased slightly (1.42 +/- 11.93 ng/ml/h) when insulin administration was combined with i.c.v. infusion of the vasopressin antagonist [deaminopenicillamine1, O-methyl-tyrosine2, arginine8]-vasopressin (120 micrograms/h; p = 0.013 vs. insulin only). The demonstration that vasopressin administration inhibits LH secretion whereas vasopressin antagonism prevents hypoglycemia-induced LH suppression suggests that vasopressin is a physiological inhibitor of LH secretion in the rhesus monkey.

Animals↗
PubMed1994

Evaluation of Brassicas in grazing systems for sheep: I. Quality of forage and animal performance.

Four years of grazing trials were conducted with Brassica forages to evaluate their chemical composition and effect on ADG of fattening lambs and breeding ewes in late fall. Brassicas tested included kales (Brassica oleracea L. var. acephala DC), turnips (B. rapa L.), and a chinese cabbage hybrid (B. rapa L. x B. pekinensis [Lour.] Rupr.). Daily gains of lambs varied widely among years (19 to 330 g/d); ADG on Brassicas were, however, generally higher than on stockpiled Kentucky 31 tall fescue (Festuca arundinacea Schreb.) or orchardgrass (Dactylis glomerata L.)-red clover (Trifolium pratense L.) pastures grazed at the same time. In 1 yr, dietary supplementation of lambs grazing a hybrid turnip (Forage Star) with iodine and copper oxide needles improved (P < .05) ADG; however, there was no effect on gains in two later years. In 2 yr, lambs showed higher ADG on Tyfon chinese cabbage hybrid (241 and 330 g/d) than on Forage Star turnip (197 and 275 g/d) or stockpiled grass-clover (135 and 233 g/d), but yield of Tyfon was lower. Indications that supplementary hay improved ADG of lambs and ewes were not confirmed in the final year, in which hay increased (P < .05) ADG of lambs in the first 3 wk of grazing Brassicas but decreased gains later. Thyroid weights were increased (P < .01) consistently in all trials on Brassicas, but enlargement was modest and not related to ADG. Brassica forages provided high yields (5.6 to 10.5 t/ha) of DM in the late fall to early winter period, with high carrying capacity for sheep but large variability in ADG.

Animal Feed↗
PubMed1994

Evaluation of Brassicas in grazing systems for sheep: II. Blood composition and nutrient status.

Blood composition of lambs grazing Brassicas and stockpiled grass or grass-clover pastures in the fall of 4 yr was monitored to assess possible effects of plant metabolites (e.g., glucosinolates, S-methyl cysteine sulfoxide) on health and performance. Serum thyroxine (T4) concentrations in lambs grazing Brassicas decreased upon initiation of grazing, with a subsequent recovery, and concentrations were increased by oral dosing with I or I+CuO. Serum triiodothyronine (T3) increased gradually with time and did not differ between lambs on Brassicas and on pasture at most time periods. In Exp. 3 and 4, T4 levels were lower in lambs grazing Tyfon chinese cabbage hybrid (Brassica rapa L. x B. pekinensis [Lour.] Rupr.) than in lambs on Forage Star hybrid turnip (B. rapa L.). Heinz body formation increased rapidly in lambs on Brassicas, with small decreases in packed cell volume (PCV); dosing with I+CuO reduced Heinz bodies in lambs on Tyfon and turnip pastures. In Exp. 2, I+CuO treatment increased liver Cu concentrations but had no effect on serum Cu. Serum cholesterol and urea N concentrations declined rapidly in lambs on Brassicas, with little change in lambs on stockpiled pastures. Decreases in serum triglycerides, and an increase in glucose concentration, were noted in Exp. 3 and 4 in lambs grazing Tyfon and Forage Star turnip. Although a number of differences related to plant composition were noted in blood of lambs grazing Brassica forages relative to stockpiled pastures, the changes did not seem sufficiently severe to affect animal performance.

Animal Feed↗
PubMed1993

The isolation of sucrose-fermenting Salmonella mbandaka.

During media trials to evaluate the use of Brilliant Green Agar for the primary recognition of Salmonella, strains presenting fermentation reactions were observed. All fermenting strains (84 out of 145) belonged to the serotype Salmonella mbandaka (58%), and the activity was expressed on three batches of Brilliant Green Agar and one of Xylose-Lysine Desoxycholate Agar. It was established using individual lactose and sucrose broth that the reaction in these media was due to sucrose fermentation. The most frequently isolated Salmonella in this laboratory during 1990 was S. mbandaka (61%) i.e. 65 of the 106 isolates during this period. Primary differentiation of Salmonella from other members of the family Enterobacteriaceae on media incorporating sucrose would have resulted in 36% of Salmonella isolates not being recognised. BGA and XLD agar therefore would not be suitable for primary isolation of Salmonella from clinical material with such a high percentage of the major isolate, S. mbandaka, having the ability to ferment sucrose.

Animals↗
PubMed1993

Evidence of lasting functional destruction of the rat endometrium after 5-aminolevulinic acid-induced photodynamic ablation: prevention of implantation.

OBJECTIVE: We evaluated disruption of endometrial function after treatment with 5-aminolevulinic acid with or without light exposure. STUDY DESIGN: In a conventional laboratory setting adult Sprague-Dawley female rats were treated with various doses of 5-aminolevulinic acid in one uterine horn and saline in the contralateral horn. Three hours after treatment both uterine horns were exposed to light, and the rats were bred to a fertile male 10 or 60 days later. Ablation of endometrium was evaluated by both rate of implantation and histologic features. RESULTS: In the absence of light exposure 5-aminolevulinic acid had no significant effect on the rate of implantation, compared with saline (76% vs 92%, n = 25, p > 0.05). In contrast, 5-aminolevulinic acid treatment plus light exposure profoundly decreased the rate of implantation in the 5-aminolevulinic acid-treated uterine horns of rats bred 10 days (3.8% vs 100%, n = 26, p < 0.001) or 60 days after treatment (16.7% vs 100%, n = 24, p < 0.001). Histologic examination revealed that the 5-aminolevulinic acid plus light-treated uterine horns were completely devoid of endometrium. CONCLUSION: Photodynamic treatment with 5-aminolevulinic acid resulted in a persistent disruption of rat endometrial function and was consistent with the histologic evidence of complete endometrial ablation. In addition, a partial destruction of myometrium adjacent to endometrium was observed. The myometrial damage may be through a nonphotodynamic mechanism because myometrium is unable to synthesize protoporphyrin IX from 5-aminolevulinic acid.

Aminolevulinic Acid↗
PubMed1993

Intrauterine 5-aminolevulinic acid induces selective fluorescence and photodynamic ablation of the rat endometrium.

5-Aminolevulinic acid (ALA), a precursor of protoporphyrin IX (Pp IX), was administered into the rat uterine cavity in an attempt to selectively ablate the endometrium. Doses of ALA ranging from 4 to 50 mg were injected into one uterine horn of rats while the vehicle (saline) was injected into the contralateral horn. Animals were divided into three groups. In group one, the uterine horns were removed and processed for either fluorescent microscopy or spectrophotofluorometry 3 h later. In group two, rats were allowed to survive for either 2 or 10 days, and then the uterine horns were harvested and processed histologically. In group three, both uterine horns were exposed to transmural light (approximately 150 J/cm2) 3 h after administration of ALA or saline and processed histologically either 2 or 10 days later. Fluorescent microscopy showed fluorescence in the endometrium and not in the myometrium. The maximum emission spectra of endometrial fluorescence occurred at 630 and 690 nm, characteristic of Pp IX. In contrast, no fluorescence was detected in saline-treated uterine horns. Light exposure resulted in extensive damage only to the ALA-treated endometrium. There was no indication of regeneration 10 days after treatment. We conclude from these studies that ALA administered into the lumen of the rat uterus is selectively converted into Pp IX within the endometrium. Furthermore, photoactivation of the Pp IX results in selective ablation of the endometrium.

Aminolevulinic Acid↗
PubMed1993

Transactivation of the P2 promoter of parathyroid hormone-related protein by human T-cell lymphotropic virus type I Tax1: evidence for the involvement of transcription factor Ets1.

Expression of the parathyroid hormone-related protein (PTHrP), a protein that plays a primary role in the development of the humoral hypercalcemia of malignancy, is regulated by two distinct promoters, P1 and P2. PTHrP is overexpressed in lymphocytes from adult T-cell leukemia patients. We now demonstrate that in the human T-cell lymphotropic virus type I-transformed cell line MT-2, RNA synthesis is initiated primarily at the P2 promoter. Furthermore, in cotransfection experiments, Tax1 transactivates the P2 promoter 10- to 12-fold. By using deletion and site-specific point mutations, we have identified a promoter-proximal sequence (positions -72 to -40) which is important for Tax1 transactivation. The PTHrP promoter-proximal element contains two potential overlapping Ets1 binding sites, EBS I and EBS II. Gel shift analysis demonstrated that Ets1 binds specifically to both EBS I and EBS II. Mutation of the consensus GGAA core motif in EBS I abolished binding and Tax1 transactivation in Jurkat T lymphocytes. In Ets1-deficient cells, cotransfection of Tax1 and Ets1 expression plasmids stimulates PTHrP promoter activity. In the absence of Ets1, minimal transactivation of the PTHrP promoter is observed. These data suggest that Ets1 binds to EBS I and cooperates with Tax1 to transactivate the PTHrP P2 promoter.

Base Sequence↗
PubMed1993

Hypoglycemia-induced inhibition of luteinizing hormone secretion in the rhesus monkey is not mediated by endogenous opioid peptides.

A role for endogenous opioid peptides in stress-induced inhibition of LH secretion has been suggested based on the observation in rats, humans, and nonhuman primates that LH inhibition in response to a variety of different stresses could be blocked by the administration of opiate antagonists. In the present study, we have examined in rhesus monkeys whether suppression of LH secretion by insulin-induced hypoglycemia is prevented by administration of the opiate antagonist naloxone. The administration of 1.0 U insulin/kg to chair-restrained ovariectomized monkeys (n = 6) decreased blood glucose levels from 4.98 +/- 0.17 to 2.08 +/- 0.05 mmol/L and increased cortisol levels from 1279 +/- 205 to 2191 +/- 475 nmol/L. LH levels declined to 62% of the levels observed in the pretreatment control period (P < 0.05). Infusion of naloxone (2-mg bolus plus 2 mg/h or 10-mg bolus plus 10 mg/h) did not reverse the effects of insulin-induced hypoglycemia on LH concentrations. The administration of 1.0 U insulin/kg to nonrestrained monkeys produced a similar hypoglycemic state. Blood glucose levels declined from 4.08 +/- 0.11 to 2.45 +/- 0.05 mmol/L, while cortisol concentrations increased from 577 +/- 53 to 1324 +/- 294 mmol/L. However, LH concentrations did not decline in response to hypoglycemia. These data indicate that hypoglycemia-induced inhibition of LH secretion in chair-restrained ovariectomized monkeys is not mediated by endogenous opiates, since naloxone failed to reverse this effect. The observation that hypoglycemia inhibited LH levels only during a period of restraint suggests either an additive or synergistic effect of these two stresses on LH secretion.

Animals↗
PubMed1993

Stabilization of wild-type p53 in human T-lymphocytes transformed by HTLV-I.

Adult T-cell leukemia/lymphoma is an aggressive malignancy associated with infection by the human T-lymphotropic virus type-I (HTLV-I). We now demonstrate that p53 expression is elevated in the HTLV-I-transformed T-lymphocyte lines C81, MT-2, MT-4 and HUT 102. In pulse-chase experiments, the p53 protein demonstrated a prolonged half-life of 2 to 8 h in HTLV-I-transformed cells compared with 0.5 to 1.0 h for wild-type p53 in primary human and murine fibroblasts, or human peripheral blood lymphocytes. In cell lines C81 and HUT 102, which exhibited the longest p53 protein half-life, the wild-type-related PAb1620 epitope was detected at reduced levels. The PAb240 mutant-related p53 epitope was not detected in any of the transformed cell lines. By direct sequence analysis of RT-PCR products, the entire p53 cDNA coding sequence was determined to be wild-type in all four cell lines. Stabilization of wild-type p53 may represent its functional inactivation and contribute to lymphocyte transformation by HTLV-I.

Base Sequence↗
PubMed1992

Extracellular Tax1 protein stimulates tumor necrosis factor-beta and immunoglobulin kappa light chain expression in lymphoid cells.

The human T-cell leukemia virus type I tax1 gene product is responsible for the increased expression of several cytokine and cellular genes that contain NF-kappa B regulatory sequences. Our laboratory has previously demonstrated that purified, extracellular Tax1 protein induced the nuclear accumulation of NF-kappa B binding activity in lymphoid cells. Since HTLV-I infection causes increased levels of lymphotoxin tumor necrosis factor-beta [TNF-beta] and immunoglobulin secretion, we have studied the interaction of NF-kappa B proteins from Tax1-stimulated cells with the TNF-beta and immunoglobulin kappa (Ig kappa) light chain genes. Tax1 induction of NF-kappa B occurred in the presence of cycloheximide, and Tax1 stimulation did not result in increased levels of NF-kappa B or c-rel RNA. These results indicate that new synthesis of NF-kappa B proteins was not required for induction of NF-kappa B-binding activity. With use of the Ig kappa NF-kappa B-binding site as a probe, two distinct NF-kappa B gel shift complexes were induced by the Tax1 protein. A slower-migrating complex, C1, was inhibited by the addition of purified I kappa B. In contrast, the faster-migrating C2 complex was not inhibited by I kappa B, but C2 was increased by detergent treatment of cytoplasmic extracts, suggesting that its binding activity was also regulated by an inhibitor. The Tax1-stimulated proteins that interacted with the NF-kappa B-binding sites in the Ig kappa and TNF-beta promoters were distinct. A 75-kDa protein preferentially associated with the Ig kappa NF-kappa B-binding site. In contrast, a 59-kDa protein associated with the TNF-beta NF-kappa B-binding site. Tax1 stimulation led to increased levels of TNF-beta and Ig kappa mRNA, as measured by reverse transcription and polymerase chain reaction analysis. These results represent the first experimental evidence that extracellular Tax1 can regulate the expression of endogenous cellular genes.

Animals↗
PubMed1992

Progesterone inhibits the estrogen-induced gonadotropin surge in the rhesus monkey independent of endogenous opiates.

Administration of an estrogen challenge during the luteal phase, a time when progesterone concentrations are elevated, fails to elicit a gonadotropin-positive feedback response. The purpose of the present study was to determine if endogenous opiates are involved in the mechanism by which progesterone blocks the estrogen-induced gonadotropin surge in monkeys. To this end, rhesus monkeys in the luteal phase were pretreated with either saline or various regimens of nalmefene, a long-acting opiate antagonist, before being given an estrogen challenge. Three groups of animals were given nalmefene (10 mg, iv) every 12 h beginning 24, 48, or 96 h before an estrogen challenge and continued until 48 h after the start of the estrogen challenge. A fourth group received a continuous sc infusion of nalmefene (20 mg/day) via osmotic minipumps beginning 48 h in advance of the estrogen challenge. In a second experiment, monkeys in the follicular phase received progesterone implants at the time of an estrogen challenge and iv injections of nalmefene every 12 h for 48 h. Gonadotropin and steroid levels were monitored in both experiments by collecting blood samples by saphenous venipuncture at intervals of 6-12 h. The majority of luteal phase animals that were pretreated with saline were unresponsive to the estrogen challenge. Only 2 of 16 (12.5%) had an increase in LH concentrations that could be classified as a surge. Animals pretreated with iv nalmefene every 12 h beginning 48 h before the estrogen challenge exhibited a higher incidence of positive feedback responses (8 of 12 or 66.7%). A concomitant FSH surge was observed in 3 of these instances. However, when progesterone concentrations, which declined before the estrogen challenge in the nalmefene-treated group, were supplemented with exogenous progesterone, nalmefene failed to evoke any LH surges. Six of 8 animals that received nalmefene by sc infusion exhibited LH responses. However, the amplitude and duration of these LH responses were diminished, and no FSH responses were observed. Monkeys pretreated with nalmefene for either shorter (24 h) or longer (96 h) periods before the challenge were less responsive (0 responses out of 6 trials and 1 response out of 4 trials, respectively). Nalmefene was equally ineffective in preventing progesterone inhibition of the estradiol-induced LH surge in follicular phase animals (0 of 15 animals had LH surge). These results indicate that nalmefene antagonism of endogenous opiates does not enable estrogen to exert positive feedback effects on LH release when progesterone levels are high, such as during the luteal phase or after progesterone administration.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗
PubMed1992

Nutritive quality and palatability of switchgrass hays for sheep: effects of cultivar, nitrogen fertilization, and time of adaptation.

Feeding and palatability trials were conducted with four cultivars (cv) of switchgrass (Panicum virgatum L.), fertilized at three levels of N (0, 75, or 150 kg of N/ha) in 2 yr. Wether sheep had ad libitum access to chopped hays, and intake, apparent digestibility, particle passage rates, and concentrations of blood metabolites were determined. Palatability was measured with mature sheep in cafeteria trials. Nitrogen fertilization did not affect (P > .05) DM digestibility (DMD) or DMI, but there was a year x N interaction (P < .01) for NDF digestibility. Dry matter digestibility values for combined years and N levels were 56.9, 54.4, 56.6, and 57.9% (P < .01) for Pathfinder, New Jersey 50, Kentucky 1625, and Trailblazer cv, respectively; mean DMI values were 60.4, 60.8, 57.7, and 64.0 g/kg BW.75 (year x cv, P < .01). An apparently greater quality of Trailblazer was masked by weed invasion of N-fertilized stands of this cv in yr 2, with changes in hay composition. Lambs adapted to hay diets with time; mean DMI for cv and N levels combined increased (P < .001) from 50.5 to 71.4 g/kg BW.75 between wk 2 and 3 and wk 10 and 11, with no change in DMD. Intakes of NDF increased from 37.6 to 55.6 g/kg BW.75, an increase of 48%. Marker (Yb) measurements indicated little change in particle passage rates with treatment. There were no major differences in blood composition, apart from increases in blood urea N, as a result of N fertilization. Cafeteria trials showed preference by sheep for Trailblazer and KY 1625 compared with NJ 50 and Pathfinder, with a N x cv interaction (P < .01). Trailblazer was preferred to KY 1625 in a two-choice situation (P < .01). Results show relatively small effects of cv and N fertilization on quality of switchgrass and indicate the need for a lengthy period of adaptation by sheep to the feeding of a warm-season grass.

Animal Feed↗