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The objective of this study was to examine cattle and deer utilization of nine different varieties of forage cereal grains. Yield and forage quality were also determined as well as apparent ruminal digestibility of select forage cereal grains. Cattle preferred annual ryegrass, followed by the oat varieties compared to wheat varieties. Deer preferred the wheat varieties and utilized the plots for the first nine weeks of the study but utilization decreased when cattle were introduced to the area. The annual cereal rye yielded the most tons per hectare followed by wheat varieties then the oat and other rye varieties. Apparent ruminal digestibility was determined through the use of fermenters that were randomly assigned to one of the following primary forage source: 1) fescue grass hay (GH); 2) ryegrass (RYE); 3) Buck Master Wheat (BMW); or 4) Buck Forage Oat (BFO). Dry matter digestibility was greater for RYE and BMW compared to GH and BFO. Neutral detergent fiber and CP digestibility were greater for RYE and BMW compared to GH and BFO. All varieties have the ability to extend grazing but more research needs to be done to determine best management practices for common use land areas.

Our previous studies indicate that oxycodone is a putative kappa-opioid agonist, whereas morphine is a well documented micro-opioid agonist. Because there is limited information regarding the development of tolerance to oxycodone, this study was designed to 1) document the development of tolerance to the antinociceptive effects of chronically infused i.v. oxycodone relative to that for i. v. morphine and 2) quantify the degree of antinociceptive cross-tolerance between morphine and oxycodone in adult male Dark Agouti (DA) rats. Antinociceptive testing was performed using the tail-flick latency test. Complete antinociceptive tolerance was achieved in 48 to 84 h after chronic infusion of equi-antinociceptive doses of i.v. oxycodone (2.5 mg/24 h and 5 mg/24 h) and i.v. morphine (10 mg/24 h and 20 mg/24 h, respectively). Dose-response curves for bolus doses of i.v. and i.c.v. morphine and oxycodone were produced in naive, morphine-tolerant, and oxycodone-tolerant rats. Consistent with our previous findings that oxycodone and morphine produce their intrinsic antinociceptive effects through distinctly different opioid receptor populations, there was no discernible cross-tolerance when i.c.v. oxycodone was given to morphine-tolerant rats. Similarly, only a low degree of cross-tolerance (approximately 24%) was observed after i.v. oxycodone administration to morphine-tolerant rats. By contrast, both i.v. and i.c.v. morphine showed a high degree of cross-tolerance (approximately 71% and approximately 54%, respectively) in rats rendered tolerant to oxycodone. Taken together, these findings suggest that, after parenteral but not supraspinal administration, oxycodone is metabolized to a mu-opioid agonist metabolite, thereby explaining asymmetric and incomplete cross-tolerance between oxycodone and morphine.

Chloramphenicol, an in vitro inhibitor of the glucuronidation of morphine to its putative antianalgesic metabolite, morphine-3-glucuronide (M3G), was coadministered with morphine in adult male Sprague-Dawley rats to determine whether it inhibited the in vivo metabolism of morphine to M3G, thereby enhancing morphine antinociception and/or delaying the development of antinociceptive tolerance. Parenteral chloramphenicol was given acutely (3-h studies) or chronically (48-h studies). Morphine was administered by the i.v. or i.c.v. route. Control rats received chloramphenicol and/or vehicle. Antinociception was quantified using the hotplate latency test. Coadministration of chloramphenicol with i.v. but not i.cv. morphine increased the extent and duration of morphine antinociception by approximately 5.5-fold relative to rats that received i.v. morphine alone. Thus, the mechanism through which chloramphenicol enhances i.v. morphine antinociception in the rat does not directly involve supraspinal opioid receptors. Acutely, parenteral coadministration of chloramphenicol and morphine resulted in an approximately 75% increase in the mean area under the serum morphine concentration-time curve but for chronic dosing there was no significant change in this curve, indicating that factors other than morphine concentrations contribute significantly to antinociception. Antinociceptive tolerance to morphine developed more slowly in rats coadministered chloramphenicol, consistent with our proposal that in vivo inhibition of M3G formation would result in increased antinociception and delayed development of tolerance. However, our data also indicate that chloramphenicol inhibited the biliary secretion of M3G. Whether chloramphenicol altered the passage of M3G and morphine across the blood-brain barrier remains to be investigated.

Bursa samples from the United States, Mexico, and Puerto Rico were tested for the presence of infectious bursal disease virus (IBDV) using the reverse transcriptase/polymerase chain reaction-restriction endonuclease (RT/PCR-RE) assay. This assay amplifies a 394-bp fragment of the IBDV VP2 gene. A total of 151 samples were tested. Each was from a different physical location or farm. Forty-eight of the samples were determined to contain IBDV using RT/PCR. The RE profiles on 44 of these positive samples were determined using the enzymes BstNI or EcoRII, StyI, DraI, SacI, Sau3AI or MboI, and TaqI. A majority of the samples (34) had RE profiles typical of variant IBDV strains. One of six samples from Mexico was positive for IBDV. This virus had an RE profile typical of variant strains of IBDV. Three of seven samples from Puerto Rico had RE profiles characteristic of variant viruses. Two samples from the United States had RE profiles characteristic of classic vaccine IBDV strains and nine samples had new RE profiles. Five of these new profiles were BstNI- and StyI-negative, indicating that these viruses may be antigenically related to variant types. Although the new RE pattern observed in the other four samples was BstNI- and StyI-positive, it was not typical of classic vaccine IBDV strains. One flock from the United States had a mixture of two RE profiles, a typical variant type profile and an unknown variant RE profile. Two-thirds of the positive samples from flocks where the age of the birds was reported were observed between 21 and 28 days of age. The results of these studies demonstrate that the RT/PCR-RE assay can be used to diagnose IBDV in chickens and that IBDV strains exist in commercially reared chickens that have RE patterns different than known IBDV strains. The molecular differences observed using the RT/PCR-RE test were in a region of the VP2 gene, which is known to code for important neutralizing epitopes and to be highly variable among IBDV strains. Although the results demonstrate RE patterns different than those observed in known classic and variant IBDV strains, the influence of these molecular differences on biological properties of the viruses requires further investigation.

A serotype 1 variant strain of infectious bursal disease virus designated IN was passaged 40 times in BGM-70 cell line. A small plaque (SP) clone and a large plaque (LP) clone were then isolated and plaque purified four times. The SP and LP viruses formed circular plaques about 0.5 mm and 6.0 mm in diameter, respectively. Both clones lost their pathogenicity for specific-pathogen-free (SPF) chickens and did not elicit significant levels of virus-neutralizing antibody titers. However, the SP and LP clones maintained their immunogenicity when used as inactivated vaccines in SPF chickens. The restriction enzyme profiles of both clones were similar. Back passage of the SP and LP clones in SPF chickens resulted in loss of their phenotypic characteristics.

Bursa samples from the United States, Mexico, and Puerto Rico were tested for the presence of infectious bursal disease virus (IBDV) using the reverse transcriptase/polymerase chain reaction-restriction endonuclease (RT/PCR-RE) assay. This assay amplifies a 394-bp fragment of the IBDV VP2 gene. A total of 151 samples were tested. Each was from a different physical location or farm. Forty-eight of the samples were determined to contain IBDV using RT/PCR. The RE profiles on 44 of these positive samples were determined using the enzymes BstNI or EcoRII, StyI, DraI, SacI, Sau3AI or MboI, and TaqI. A majority of the samples (34) had RE profiles typical of variant IBDV strains. One of six samples from Mexico was positive for IBDV. This virus had an RE profile typical of variant strains of IBDV. Three of seven samples from Puerto Rico had RE profiles characteristic of variant viruses. Two samples from the United States had RE profiles characteristic of classic vaccine IBDV strains and nine samples had new RE profiles. Five of these new profiles were BstNI- and StyI-negative, indicating that these viruses may be antigenically related to variant types. Although the new RE pattern observed in the other four samples was BstNI- and StyI-positive, it was not typical of classic vaccine IBDV strains. One flock from the United States had a mixture of two RE profiles, a typical variant type profile and an unknown variant RE profile. Two-thirds of the positive samples from flocks where the age of the birds was reported were observed between 21 and 28 days of age. The results of these studies demonstrate that the RT/PCR-RE assay can be used to diagnose IBDV in chickens and that IBDV strains exist in commercially reared chickens that have RE patterns different than known IBDV strains. The molecular differences observed using the RT/PCR-RE test were in a region of the VP2 gene, which is known to code for important neutralizing epitopes and to be highly variable among IBDV strains. Although the results demonstrate RE patterns different than those observed in known classic and variant IBDV strains, the influence of these molecular differences on biological properties of the viruses requires further investigation.

A serotype 1 variant strain of infectious bursal disease virus designated IN was passaged 40 times in BGM-70 cell line. A small plaque (SP) clone and a large plaque (LP) clone were then isolated and plaque purified four times. The SP and LP viruses formed circular plaques about 0.5 mm and 6.0 mm in diameter, respectively. Both clones lost their pathogenicity for specific-pathogen-free (SPF) chickens and did not elicit significant levels of virus-neutralizing antibody titers. However, the SP and LP clones maintained their immunogenicity when used as inactivated vaccines in SPF chickens. The restriction enzyme profiles of both clones were similar. Back passage of the SP and LP clones in SPF chickens resulted in loss of their phenotypic characteristics.

A variety of N-alkyl-N'-pyridyl-N"-cyanoguanidines III was prepared as potential bioisosteres of hypotensive N-alkyl-N'-pyridylthioureas Ia. Optimal activity of the N,N'-disubstituted cyanoguanidines III was assoicated with the presence of four to seven carbon branched alkyl and 3- or 4-pyridyl groups. Maximum potency was displayed by N-tert-pentyl-N'-3 pyridyl-N"-cyanoguanidine (20). This compound proved to be 200 times more potent than the corresponding thiourea in hypertensive rats and dogs. In comparison with guancydine, which is the de-3-pyridyl analogue of 20, a 150-fold increase of potency in spontaneously hypertensive rats was obtained with 20 and its tert-butyl analogue 19. The observed activity appears to be due to direct vascular relaxation. On a weight basis compounds 19, 20, 50, and 101 compared favorably with hydralazine.

A variety of N-alkyl-N'-pyridyl-N"-cyanoguanidines III was prepared as potential bioisosteres of hypotensive N-alkyl-N'-pyridylthioureas Ia. Optimal activity of the N,N'-disubstituted cyanoguanidines III was assoicated with the presence of four to seven carbon branched alkyl and 3- or 4-pyridyl groups. Maximum potency was displayed by N-tert-pentyl-N'-3 pyridyl-N"-cyanoguanidine (20). This compound proved to be 200 times more potent than the corresponding thiourea in hypertensive rats and dogs. In comparison with guancydine, which is the de-3-pyridyl analogue of 20, a 150-fold increase of potency in spontaneously hypertensive rats was obtained with 20 and its tert-butyl analogue 19. The observed activity appears to be due to direct vascular relaxation. On a weight basis compounds 19, 20, 50, and 101 compared favorably with hydralazine.