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Biomedical subjects

K L Watkins

Publications and source records attributed to K L Watkins.

At least 19 recordsLinked to original sources
PubMed2005

Japanese encephalitis in a racing thoroughbred gelding in Hong Kong.

A horse in Hong Kong that had been vaccinated against Japanese encephalitis suffered a pyrexic episode that culminated in a hyperexcitable state and self-inflicted trauma. Japanese encephalitis was diagnosed on the basis of clinical, pathological and serological observations, and confirmed by the detection of genomic sequences of the virus in spinal cord tissue. Phylogenetic analyses of E gene and NS5-3'UTR sequences revealed divergent clustering of these segments with previously described genotypes, suggesting the possibility that the horse might have been infected with a recombinant between genotype I and genotype II viruses. Horses are considered to be dead-end hosts for the disease, but the occurrence of an infected horse in a population may have implications for the health status of the national herd. The effect that this case had on the horse industry in Hong Kong is discussed with specific reference to the movement of horses and the vaccination programme for Japanese encephalitis.

Animals↗
PubMed1997

In-vitro antimicrobial susceptibility of Clostridium perfringens from commercial turkey and broiler chicken origin.

The minimum inhibitory concentrations (MIC) of eight antibiotics and two anticoccidial agents were determined for Clostridium perfringens strains isolated from 26 commercial broiler farms and 22 commercial turkey farms. Isolates were obtained from the intestines of birds on the farm or as the processing plant using standard culture and identification techniques. The microbroth dilution test was used to determine the MIC for each compound. Most isolates from chickens had MICs in the range of 2-16 mg/L for tilmicosin, tylosin and virginiamycin, whereas the MICs for avilamycin, avoparcin, monensin, narasin and penicillin were < or = 1 mg/L. Most strains from chickens had high MICs (> or = 64 mg/L) and appeared to be resistant to bacitracin and lincomycin. Most turkey isolates had MICs in the range of 2-16 mg/L for bacitracin, tilmicosin, tylosin and virginiamycin, with strains exhibiting MICs < or = 1 mg/L for avilamycin, avoparcin, monensin, narasin and penicillin. Several turkey isolates had MICs > or = 64 mg/L to lincomycin. No attempt was made to associate farm usage of a particular antibiotic to the antibiograms.

Animals↗
PubMed1995

Outbreak of equine influenza among horses in Hong Kong during 1992.

Equine-2 influenza virus A (H3N8) infection occurred among vaccinated thoroughbred horses in Hong Kong during November and December 1992. The outbreak was unique in that it occurred among a large population stabled under intensive conditions. It resulted in the postponement of seven race meetings over a period of 32 days. The outbreak originated after the importation of horses 25 to 32 days before any clinical signs were reported. Vaccination did not prevent 75 per cent of the population from becoming infected, and half the infected horses developed clinical signs. Vaccination did, however, contribute to reducing the morbidity and the severity and duration of the clinical signs.

Animals↗
PubMed1995

Interactive effects of dietary copper, water copper, and Eimeria spp. infection on growth, water intake, and plasma and liver copper concentrations of poults.

The effects of dietary Cu, water Cu, and coccidial infection on poult growth performance and selected tissue mineral concentrations were investigated in a 10-d experiment using 200 5-d-old Nicholas toms (five replicates of 5 poults each; initial weight = 85 g). Uninfected and coccidiosis-infected (Eimeria meleagrimitis, Eimeria dispersa, Eimeria adenoeides, and Eimeria gallopavonis; cocci) poults were assigned to two levels of dietary Cu [Basal (B) and B + 204 mg Cu/kg diet on Days 1 to 10] and two levels of water Cu (0 and 103 mg Cu/kg water on Days 6 to 10). Dietary Cu and water Cu (main effects) did not affect (P > .10) gain, feed intake, gain:feed, water intake, hemoglobin, hematocrit, or liver Fe and Zn concentrations. Dietary Cu and water Cu increased (P < .03) liver and plasma Cu concentrations. The combination of dietary Cu and water Cu increased plasma Cu more than the sum of the Cu additions (dietary Cu by water Cu, P < .08). Coccidial infection reduced (P < .07) gain, feed intake, gain:feed, water intake, and hemoglobin, and increased (P < .02) liver Zn. Water Cu reduced water intake in uninfected poults but increased water intake in coccidiosis-infected poults (water Cu by cocci, P < .07). Water Cu increased hemoglobin in uninfected poults but decreased hemoglobin in coccidiosis-infected poults (water Cu by cocci, P < .07). Water Cu increased plasma Cu and liver Cu more in coccidiosis-infected poults than in uninfected poults (water Cu by cocci, P < .02).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

The effect of in ovo oocyst or sporocyst inoculation on response to subsequent coccidial challenge.

A trial was conducted to investigate the effects of in ovo Eimeria maxima inoculation on response to subsequent posthatch challenge with E. maxima. The in ovo treatments were arranged in a 4 x 2 factorial with four in ovo inoculation sites (air cell, amnion, yolk sac, and allantois) and two parasite forms (oocyst and sporocyst). Four control treatments included an uninoculated (naive) unchallenged group, a naive challenged group, and two posthatch inoculated challenged groups. Chicks were challenged by crop intubation with 50,000 sporulated E. maxima oocysts 10 d posthatch. On Day 8 postchallenge, feed intake was determined and birds were weighed and lesions scored. During the brooding period, oocysts were isolated from the fecal material of chicks receiving in ovo administration of sporocysts in the amnion and sporocysts or oocysts in the yolk sac. Posthatch inoculated chicks had gain and feed:gain ratios similar to those of naive unchallenged chicks. Gain, feed:gain ratio, lesion scores, and oocyst shedding of chicks inoculated in ovo were similar to those of naive, challenged chicks. Although there was some indication that parasites introduced in ovo may complete their life-cycle within the developing chick, this experiment provided no evidence that in ovo administration of either E. maxima oocysts or sporocysts will protect birds from subsequent coccidial challenge. Contrarily, inoculating chicks on day of hatch with a single oral dose of E. maxima oocysts provided significant protection against subsequent coccidial challenge.

Animals↗
PubMed1994

Rapid diagnosis of equine influenza by the Directigen FLU-A enzyme immunoassay.

The Directigen FLU-A enzyme immunoassay was tested for its ability to detect equine-2 influenza viruses in nasopharyngeal fluids from horses and ponies. A total of 125 swabs from experimental infections and from different sources of natural infection in the USA and Hong Kong were examined. The assay results were compared with the results of standard virus culture in embryonated chicken eggs or Madin-Darby canine kidney cells, and with the serology of the horses sampled. In comparison with virus culture the enzyme immunoassay exhibited 83 per cent sensitivity, 78 per cent specificity, 70 per cent positive predictive value and 88 per cent negative predictive value. The test appeared to be more sensitive than haemagglutination for the detection of low levels of virus in embryonated egg cultures. It also detected equine-1 influenza virus in culture. The test is rapid (15 minutes), simple, and should be a convenient method for the rapid diagnosis and screening of horses for equine influenza infection.

Animals↗
PubMed1994

Exposure to biogenic silica fibers and respiratory health in Hawaii sugarcane workers.

We conducted a cross-sectional environmental and medical survey of 355 male sugarcane workers in Hawaii to determine whether exposure to biogenic silica fibers (BSF) affected their respiratory health. Exposures to BSF ranged from nondetectable to more than 0.700 BSF/mL and varied by job and department. Respiratory symptoms, chest radiograph findings, and pulmonary function were not associated with BSF exposures. Cigarette smoking was associated with respiratory symptoms and pulmonary obstruction. Fifteen workers had pleural thickening or pleural plaques and 3 of these workers were exposed to BSF for more than 10 years. BSF exposure does not appear to influence the respiratory health of sugarcane workers; however, further study is warranted.

Agriculture↗
PubMed1994

Feed gorging and extended water restriction do not produce knockdown in male turkeys fed monensin.

A study was conducted to determine the effects of feed restriction with subsequent gorging during extended water restriction on 27- to 57-d-old toms fed excess monensin. Four treatments were factorially arranged with two levels of dietary monensin (0 and 140 ppm) and two feeding-watering regimens (ad libitum and restricted). Ad libitum birds had full access to feed and water but restricted birds only had access to feed from 0800 to 1200 h daily. A 24-h water restriction regimen was imposed biweekly from 28 to 42 d and a 36-h water restriction regimen was imposed biweekly from 43 to 57 d. The restricted feeding and watering regimen decreased (P < .01) feed intake, weight gain, and feed efficiency. Excess monensin had no effect (P > .10) on feed intake regardless of feeding and watering regimen. Monensin had no effect on the weight gain and feed efficiency of ad libitum birds, but monensin exacerbated the decrease on gain (monensin by regimen, P < .01) and feed efficiency (monensin by regimen, P < .09) induced by feed and water restriction. No treatment-related abnormalities were observed during either interim or terminal necropsies. Neither clinical signs of ionophore toxicity nor pathologic findings attributed to monensin treatment were observed during the study. Based on these observations, feed gorging and water restriction will not adversely affect the health status of, or increase the mortality rate of, 4- to 8-wk-old male turkeys fed monensin.

Animals↗
PubMed1994

Interactive effects of dietary copper and water copper level on growth, water intake, and plasma and liver copper concentrations of poults.

The interactive effects of dietary Cu and water Cu on poult growth, water intake, whole-blood hemoglobin (Hb), and plasma and liver Cu concentrations were investigated using 232-9-old toms. Poults were randomly assigned to two levels of dietary Cu [Basal (B) and B + 204 mg Cu/kg diet] and to four levels of water Cu (0, 51.5, 103, and 206 mg Cu/kg water) in a 2 x 4 factorial arrangement of treatments. Each treatment was replicated six times. All poults received tap water during Days 1 to 5 followed by the water Cu treatments during Days 6 to 10. Water intake was measured daily and gain and feed intake were determined on Days 5 and 10. Day 1 to 5 gain was reduced (P < .02) in poults fed supplemental dietary Cu. Day 1 to 5 feed intake and gain:feed and Day 6 to 10 gain, feed intake, gain:feed, and water intake were not affected (P > .10) by dietary Cu.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Effect of dietary sodium zeolite A on zinc utilization by chicks.

Two experiments were conducted with chicks from 5 to 15 days posthatching to study the effect of sodium zeolite A (SZA) on Zn utilization. The corn-soybean meal basal diet was supplemented with ZnCO3 to provide three levels of dietary Zn (35, 40, and 85 ppm) in Experiment 1, and two levels of dietary Zn (85 and 4,000 ppm) in Experiment 2. Experimental diets also contained either 0 or .75% SZA, resulting in a 3 x 2 and a 2 x 2 factorial arrangement of treatments in Experiments 1 and 2, respectively. The tendency for increased growth, feed intake, and hematocrit in chicks fed Zn-supplemented diets in Experiment 1 suggests that the 35-ppm level of Zn in the basal diet was marginal for chicks. Both supplemental Zn and SZA increased (P < .02) hematocrit and plasma, pancreas, and tibia Zn and decreased (P < .02) tibia Cu. Sodium zeolite A increased (SZA by Zn, P < .03) tibia Al and tended to increase (SZA by Zn, P < .09) liver Fe in chicks fed either 35 or 85 ppm Zn, but SZA had no effect on tibia Al and liver Fe in chicks fed 40 ppm Zn. In Experiment 2, both SZA and excess dietary Zn decreased gain, feed intake, gain: feed, hematocrit, hemoglobin, and plasma alkaline phosphatase (AP) activity, and increased tibia, liver, and pancreas Zn, and tibia Al. In addition, excess Zn increased (P < .05) plasma Zn and liver Al but decreased (P < .01) plasma, liver, and pancreas Cu and percentage of tibia ash. The addition of SZA enhanced the adverse effects of excess Zn by further decreasing feed intake, hematocrit, hemoglobin, and plasma AP and Cu and by increasing tibia Al and liver Zn. Sodium zeolite A increased pancreas (P < .09) and tibia (P < .03) Zn regardless of dietary Zn concentration; however, SZA increased plasma Zn only in chicks fed 85 ppm Zn (SZA by Zn, P < .03). Sodium zeolite A tended to improve Zn utilization in chicks fed inadequate Zn but exacerbated the adverse effects of feeding excess Zn. The addition of SZA to the diet of chicks fed inadequate, adequate, or toxic levels of Zn resulted in increased tissue Zn concentration.

Alkaline Phosphatase↗
PubMed1993

Research note: interactive effects of sodium zeolite A and Eimeria acervulina infection on growth and tissue minerals in chicks.

Two experiments were conducted to assess the interactive effects of dietary sodium zeolite A (SZA) and experimental Eimeria acervulina infection on growth and tissue mineral concentrations in chicks. The average initial weight of the chicks was 71.8 g, and the experimental periods were from 5 to 15 days posthatching. In both experiments, the corn-soybean meal basal diet was supplemented with 0 or .75% SZA and fed to uninfected chicks or to chicks infected with 4 x 10(5) sporulated E. acervulina oocysts on Days 0, 3, and 6 of the experiments. Both coccidial infection and SZA reduced (P < .05) gain and feed intake; however, feed efficiency was reduced (P < .01) only in the coccidiosis-infected chicks. Neither SZA nor the coccidial infection affected (P > .10) plasma Ca or P, tibia P, liver Ca, Zn, Fe, or Mn, or pancreas Cu. Sodium zeolite A increased (P < .05) plasma Zn but only in uninfected chicks (SZA by coccidiosis, P < .10). The coccidial infection decreased (P < .02) tibia ash percentage. Sodium zeolite A decreased tibia Ca in uninfected chicks but increased tibia Ca in coccidiosis-infected chicks (SZA by coccidiosis, P < .10). The coccidial infection increased (P < .05) tibia Mg, Cu, Fe, Pb, Mn, and Al concentrations. Dietary SZA also increased (P < .02) tibia Zn, Mn, and Al concentrations. The coccidial infection decreased (P < .02) tibia Zn concentration, and SZA decreased (P < .05) tibia Mg and Fe. Sodium zeolite A by coccidiosis interactions (P < .10) were evident in tibia Zn, Fe, Mn, and Al concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Effect of dietary sodium bicarbonate on growth, liver copper concentration and incidence of gastric ulceration in pigs fed excess dietary copper.

An experiment was conducted with growing-finishing pigs to evaluate the interactive effects of dietary sodium bicarbonate (1%) and excess dietary Cu (250 mg/kg diet) on growth, liver Cu accumulation and incidence of gastric ulceration. A 2 x 2 factorial arrangement of treatments was used and each treatment was replicated four (Trial 1) or three (Trial 2) times with four pigs per replicate. Initial weight of the pigs was 57 (Trial 1) and 32 kg (Trial 2). Growth rate and efficiency of feed utilization were not affected (P > .10) by treatment. Sodium bicarbonate increased (P < .06) the incidence of gastric ulceration and decreased (P < .01) dressing percentage. Dietary Cu (P < .01) increased liver Cu concentration but did not affect (P > .10) the incidence of gastric ulceration.

Animal Feed↗
PubMed1992

Effect of monensin on ultrastructure and cellular invasion by the turkey coccidia Eimeria adenoeides and Eimeria meleagrimitis.

Freshly excysted sporozoites (SZ) of the turkey coccidia Eimeria meleagrimitis and Eimeria adenoeides were incubated at 41 C in concentrations of monensin from .01 to 1.0 microgram/mL, washed free of the drug, and either processed for phase, fluorescence, and transmission electron microscopy or inoculated into cultures of turkey kidney cells. Phase microscopy indicated that after 1.5 h incubation in 1.0 micrograms/mL monensin, about 60% of the SZ of E. meleagrimitis had become notably rounded or displayed localized protrusions. These alterations were accompanied by ultrastructural abnormalities (in 90% of the SZ) including vacuoles in the cytoplasm, bulging and separation of plasma membrane layers, and dense bands in the refractile bodies that extended toward the periphery of the refractile body. Similar morphological and ultrastructural changes were observed in over half of the E. adenoeides SZ after 2 h incubation in 1.0 micrograms/mL monensin. Additionally, some specimens contained a pycnotic nucleus that was usually surrounded by a large vacuole. After 4 h incubation, almost all of the SZ displayed some degree of ultrastructural damage. Indirect fluorescent antibody labeling with parasite-specific monoclonal antibodies demonstrated clouds of antigen surrounding the monensin-treated but not the untreated SZ, suggesting an increase in permeability with incubation in monensin. With both E. meleagrimitis and E. adenoeides, the structural changes were reflected in a significant inhibition of cellular invasion. The inhibitory activity of monensin was concentration- and time-dependent in that the greatest inhibition of invasion was observed in SZ incubated for 4 h in 1.0 micrograms/mL of monensin; shorter incubation times or lower concentrations of monensin having less effect.

Animals↗
PubMed1992

Effect of dietary sodium zeolite A and graded levels of calcium and phosphorus on growth, plasma, and tibia characteristics of chicks.

Sodium zeolite A (SZA), a synthetic sodium aluminosilicate having a high ion exchange capacity, has been shown to influence Ca and P utilization in chickens. A 3 x 2 x 2 factorial arrangement of treatments was used to investigate the effect of dietary P (.41, .55, and .69% total P), Ca (.6 and 1%), and SZA (0 and .75%) on growth, plasma, and tibia characteristics of chicks from 5 to 15 days of age. Growth, feed intake, gain:feed ratio, and tibia characteristics were influenced by dietary Ca and P in a manner consistent with dietary recommendations for these macro minerals. The addition of Ca, SZA, or both exacerbated the adverse effects of feeding low-P diets, yet alleviated the adverse effects of feeding a low-Ca, high-P diet. Dietary SZA had no effect (P greater than .5) on plasma Ca or alkaline phosphatase; however, SZA reduced (P less than .01) plasma P. Dietary SZA increased (P less than .02) tibia Mn, Zn, Cu, and Al. The SZA-induced increase in tibia Al was most evident in chicks fed low levels of P (SZA by P interaction, P less than .02). The overall response to dietary SZA addition paralleled the response observed from Ca supplementation, indicating that SZA increased Ca utilization, reduced P utilization, or contributed to both of these effects. These data demonstrate that the effects of SZA are influenced by the dietary concentration of Ca and P and that the addition of SZA to diets low in P results in bone Al accumulation.

Alkaline Phosphatase↗
PubMed1991

Effect of dietary biotin supplementation on sow reproductive performance and soundness and pig growth and mortality.

A 3-yr study was conducted to evaluate the effect of dietary biotin supplementation on the reproductive performance of 90 sows and gilts, and on the pre-weaning growth and mortality of 223 litters. Corn-soybean meal-based diets supplemented with either 0 or 440 micrograms/kg d-biotin were fed to sows throughout their reproductive cycle. Biotin supplementation had no beneficial effect (P greater than .10) on 107-d sow weight, sow weight at weaning, weaning to estrus interval, foot lesion score, hair loss score, structural soundness score, number of pigs born, number and percentage of pigs born alive or number and percentage of pigs alive at 21 d of age. Biotin supplementation had no effect (P greater than .10) on pig growth or mortality to 21 d of age. These data do not support the concept that biotin supplementation of sow diets is needed.

Animals↗