Effects of maternal winter vs. year-round supplementation of protein and energy on postnatal growth, immune function, and carcass characteristics of Bos indicus-influenced beef offspring.

This 2-yr study evaluated the effects of winter vs. year-round supplementation of Bos indicus-influenced beef cows on cow reproductive performance and impact on their offspring. On day 0 of each year (approximately day 122 ± 23 of gestation), 82 to 84 mature Brangus cows/yr were stratified by body weight (BW; 475 ± 67 kg) and body condition score (BCS; 4.85 ± 0.73) and randomly assigned to 1 of 6 bahiagrass (Paspalum notatum) pastures (13 to 14 cows/pasture). Treatments were randomly assigned to pastures consisting of winter supplementation with molasses + urea (WMOL), or year-round supplementation with molasses + urea (YMOL) or wheat middling-based range cubes (YCUB). Total yearly supplement DM amount was 272 kg/cow and supplements were formulated to be isocaloric and isonitrogenous (75% TDN and 20% CP). On day 421 (weaning; approximately 260 ± 24 d of age), 33 to 35 steers/yr were vaccinated against parainfluenza-3 (PI3) and bovine viral diarrhea virus type 1 (BVDV-1) and transported 1,193 km to a feedlot. Steers were penned according to maternal pasture and managed similarly until slaughter. Data were analyzed using the MIXED and GLIMMIX procedures of SAS. On day 217 (start of breeding season), BCS was greater (P = 0.01) for YMOL than WMOL cows, whereas BCS of YCUB did not differ (P ≥ 0.11) to both WMOL and YMOL cows. The percentage of cows that calved, calving date, birth BW, and preweaning BW of the first offspring did not differ (P ≥ 0.22) among maternal treatments. Plasma cortisol concentrations were greater (P ≤ 0.001) for YCUB steers at feedlot arrival (day 422) than WMOL and YMOL steers. Moreover, YCUB steers had greater (P = 0.02) and tended (P = 0.08) to have greater plasma concentrations of haptoglobin compared to WMOL and YMOL steers, respectively. Antibody titers against PI3 and BVDV-1 viruses did not differ (P ≥ 0.25) among maternal treatments. Steer BW at feedlot exit was greater (P ≤ 0.05) for YMOL and WMOL than YCUB steers. However, feedlot DMI did not differ (P ≥ 0.37) by maternal treatment. Hot carcass weight, yield grade, LMA, and marbling did not differ (P ≥ 0.14) among maternal treatments. Percentage of steers that graded low choice was enhanced (P ≤ 0.05) for WMOL and YCUB than YMOL steers. Maternal year-round supplementation of range cubes or molasses + urea either did not impact or decrease growth, immune function, and carcass characteristics of the offspring when compared with maternal supplementation of molasses + urea during winter only.

Timing of maternal supplementation of dried distillers grains during late gestation influences postnatal growth, immunocompetence, and carcass characteristics of Bos indicus-influenced beef calves.

This 2-yr study investigated the timing of dried distillers grains (DDG) supplementation during the third trimester of gestation of Bos indicus-influenced beef cows and its impact on their offspring performance. On day 0 of each year (84 d before calving), Brangus cows (n = 84/yr; cow age = 8 ± 3 yr) were stratified by initial body weight (BW; 482 ± 75 kg) and body condition score (BCS; 5.3 ± 0.8) and assigned randomly to one of six bahiagrass (Paspalum notatum) pastures (experimental units; 14 cows/pasture). Treatments were assigned randomly to pasture (2 pastures/treatment/yr) and consisted of no prepartum supplementation (CON), 2 kg/d of DDG from day 0 to 42 (LATE42), or 1 kg/d of DDG from day 0 to 84 (LATE84). Following calving (day 84), cow-calf pairs remained in their respective pastures, and cows were offered sugarcane molasses + urea (1.82 kg of dry matter/cow/d) from day 85 until the end of the breeding season (day 224). On day 347, steer calves (n = 38/yr; 11 to 15 steers/treatment/yr) were weaned and transported to the feedlot (1,193 km). Steers were penned according to cow prepartum pasture and managed similarly until the time of harvest. BCS at calving was greater (P < 0.01) for LATE42 and LATE84 vs. CON cows but did not differ (P = 0.16) between LATE42 and LATE84 cows. Calving date, calving percentage, and birth BW of the first offspring did not differ (P ≥ 0.22) among treatments. However, LATE42 cows calved their second offspring 8 d earlier (P = 0.04) compared with CON and LATE84 cows. At weaning (first offspring), LATE84 calves were the heaviest (P ≤ 0.05), CON calves were the lightest, and LATE42 calves had intermediate BW (P ≤ 0.05). Steer plasma concentrations of cortisol and haptoglobin and serum bovine viral diarrhea virus type-1 titers did not differ (P ≥ 0.21) between treatments. Steer serum parainfluenza-3 titers were greater (P = 0.03) for LATE42 vs. CON steers, tended to be greater (P = 0.10) for LATE84 compared with CON steers, and did not differ (P = 0.38) between LATE42 and LATE84 steers. Steer feedlot BW, average daily gain, dry matter intake, and hot carcass weight did not differ (P ≥ 0.36) between treatments. Marbling and the percentage of steers grading choice were greater (P ≤ 0.04) for LATE42 vs. CON steers, whereas LATE84 steers were intermediate. In summary, different timing of DDG supplementation during the third trimester of gestation could be explored to optimize cow BCS and offspring preweaning growth and carcass quality.

This 2-yr study evaluated the effect of the timing of dried distillers grains (DDG) supplementation during the last trimester of gestation in Bos indicus-influenced beef cows and the subsequent impact on their offspring. Brangus cows were allocated to one of the three prepartum treatments consisting of no prepartum supplementation, 2 kg/d of DDG for the first half of the last trimester of gestation, or 1 kg/d of DDG for the entire length of the last trimester of gestation. Prepartum supplementation, regardless of supplementation length, improved cow body condition scores at the time of calving. Calf birth weights were not affected by prepartum maternal treatment. Calves born to cows that received prepartum supplementation had greater weaning weight compared with no prepartum supplementation. However, weaning weights were improved to the greatest extent when calves were born to cows that received supplementation for the entire length of late gestation. Steer antibody response to parainfluenza-3 was improved with prepartum maternal supplementation, regardless of supplementation length. Furthermore, concentrating the total amount of supplement offered to the first half of the last trimester of gestation improved marbling and increased the percentage of steers grading choice compared with no prepartum supplementation or supplementation during the entire last trimester.

Transcriptomics reveal different metabolic strategies for acid resistance and gamma-aminobutyric acid (GABA) production in select Levilactobacillus brevis strains.

BACKGROUND: Of the many neurotransmitters in humans, gamma-aminobutyric acid (GABA) shows potential for improving several mental health indications such as stress and anxiety. The microbiota-gut-brain axis is an important pathway for GABAergic effects, as microbially-secreted GABA within the gut can affect host mental health outcomes. Understanding the molecular characteristics of GABA production by microbes within the gut can offer insight to novel therapies for mental health. RESULTS: Three strains of Levilactobacillus brevis with syntenous glutamate decarboxylase (GAD) operons were evaluated for overall growth, glutamate utilization, and GABA production in typical synthetic growth media supplemented with monosodium glutamate (MSG). Levilactobacillus brevis Lbr-6108™ (Lbr-6108), formerly known as L. brevis DPC 6108, and Levilactobacillus brevis Lbr-35 ™ (Lbr-35) had similar growth profiles but differed significantly in GABA secretion and acid resistance. Lbr-6108 produced GABA early within the growth phase and produced significantly more GABA than Lbr-35 and the type strain Levilactobacillus brevis ATCC 14869 after the stationary phase. The global gene expression during GABA production at several timepoints was determined by RNA sequencing. The GAD operon, responsible for GABA production and secretion, activated in Lbr-6108 after only 6 h of fermentation and continued throughout the stationary phase. Furthermore, Lbr-6108 activated many different acid resistance mechanisms concurrently, which contribute to acid tolerance and energy production. In contrast, Lbr-35, which has a genetically similar GAD operon, including two copies of the GAD gene, showed no upregulation of the GAD operon, even when cultured with MSG. CONCLUSIONS: This study is the first to evaluate whole transcriptome changes in Levilactobacillus brevis during GABA production in different growth phases. The concurrent expression of multiple acid-resistance mechanisms reveals niche-specific metabolic functionality between common human commensals and highlights the complex regulation of GABA metabolism in this important microbial species. Furthermore, the increased and rapid GABA production of Lbr-6108 highlights the strain's potential as a therapeutic and the overall value of screening microbes for effector molecule output.

Evaluation of Resistance to Fescue Toxicosis in Purebred Angus Cattle Utilizing Animal Performance and Cytokine Response.

Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue; however, varying symptomatic responses potentially imply genetic tolerance to the syndrome. It was hypothesized that a subpopulation of animals within a herd would develop tolerance to ergot alkaloid toxicity. Therefore, the goals of this study were to develop selection criteria to identify tolerant and susceptible animals within a herd based on animal performance, and then examine responsive phenotypic and cytokine profiles to fescue toxicosis. Angus cows grazed endophyte-infected tall fescue at two locations for 13 weeks starting in mid-April 2016. Forage measurements were collected to evaluate ergot alkaloid exposure during the study. A post hoc analysis of animal performance was utilized to designate cattle into either tolerant or susceptible groups, and weekly physiological measurements and blood samples were collected to evaluate responses to chronic exposure to endophyte-infected tall fescue. Findings from this study support the proposed fescue toxicosis selection method formulated herein, could accurately distinguish between tolerant and susceptible animals based on the performance parameters in cattle chronically exposed to ergot alkaloids, and provides evidence to warrant additional analysis to examine the impact of ergot alkaloids on immune responsiveness in cattle experiencing fescue toxicosis.

Effects of endophyte-infected tall fescue seed and protein supplementation on stocker steers: I. Growth performance and hemodynamic responses.

Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue and is detrimental to growth and performance. Recent research has shown that supplementing protein has the potential to enhance growth performance in weaned steers. Therefore, the objective of this study was to evaluate the effect of supplemental CP on physiological parameters in stocker steers experiencing fescue toxicosis. Thirty-six weaned Angus steers (6 mo of age) stratified by weight (196.1 ± 3.6 kg) were assigned to a 2 × 2 factorial arrangement for 56 d: endophyte-free (EF) seed and 14% CP (EF-14; n = 9), EF seed and 18% CP (EF-18; n = 9), endophyte-infected (EI) seed and 14% CP (EI-14; n = 9), and EI seed and 18% CP (EI-18; n = 9). Steer growth and hemodynamic responses were collected weekly during ergot alkaloid exposure. On day 14 of the trial, iButton temperature data loggers were subcutaneously inserted in the lateral neck region to record hourly body temperature for 42 d. Data were analyzed using PROC MIXED of SAS with repeated measures. No differences were observed in DMI, BW, ADG, F:G, or BCS during the treatment period (P > 0.05). Hair shedding scores, rectal temperatures, surface temperatures, and respiration rates were greater in EI steers compared to EF steers regardless of supplemental CP (P < 0.05). However, subcutaneous body temperature was greater in EI-14 steers (37.94 °C) compared to other steer groups (37.60, 37.68, 37.72 ± 0.04 °C for EF-14, EF-18, and EI-18, respectively; P < 0.05). Prolactin concentrations tended to be greater in EF steers when compared to EI steers (P = 0.07). Heart rate and hematocrit were reduced for EI-18 steers compared to other steer groups (P < 0.05). Caudal artery diameter was reduced in EI-18 steers compared to EI-14 steers (2.60 vs. 2.75 ± 0.05 mm, respectively; P < 0.05) and caudal vein diameter was reduced in EI-18 steers (3.20 mm) compared to all other steer groups (3.36, 3.39, 3.50 mm for EF-14, EF-18, and EI-14, respectively; P < 0.05). However, there was no difference observed in systolic or diastolic blood pressure during the treatment period (P > 0.05). Based on the data, exposure to low to moderate levels of ergot alkaloids during the stocker phase had a negative impact on hemodynamic responses and supplemental CP had minimal impact to alleviate symptoms. Therefore, feeding additional protein above established requirements is not expected to help alleviate fescue toxicosis.

Effects of endophyte-infected tall fescue seed and protein supplementation on stocker steers: II. Adaptive and innate immune function.

Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue that affects performance; however, little information is available pertaining to its effects on immunity. Recently, it has been shown that supplemental CP can improve performance in weaned steers postvaccination. Thus, the objective of this study was to evaluate the effect of supplemental CP on innate and adaptive immune responses in stocker steers chronically exposed to ergovaline. Angus steers (n = 12 pens; 3 steers/pen) were stratified by weight and assigned to a 2 × 2 factorial arrangement to examine crude protein levels of supplement (14% or 18%) and ergovaline exposure (0 or 185 µg ergovaline/kg BW/d via ground endophyte-free (EF) or endophyte-infected (EI) tall fescue seed, respectively) on immune response. Consumption of low to moderate concentration of ergovaline from EI tall fescue seed was sufficient to induce mild symptoms associated with fescue toxicosis. Blood samples were collected at day 0, 42, and 56 to evaluate infectious bovine rhinotracheitis (IBR) and bovine viral diarrhea virus (BVDV) type 1b titers following vaccine challenge. Additionally, serum cytokine concentrations were evaluated using Quantibody Bovine Cytokine Arrays on day 0, 28, and 42. Data were analyzed using PROC MIXED of SAS with repeated measures. Regardless of treatment, no differences were observed in IBR and BVDV-1b seroconversion following vaccine challenge (P > 0.05). Regardless of crude protein concentration, EI steers had greater concentrations of proinflammatory cytokines (TNF-α, IFN-γ, IL-1α), chemokines (CCL2, CCL4, MIG), anti-inflammatory cytokines (IL-2, -13, -15, -21), and various growth factors (FGF-1, IGF-1, VEGF-A) when compared to EF steers (P < 0.05). Furthermore, VEGF-A and IGF-1 concentrations were greater in EI-14 steers on day 28 compared to EI-18, EF-14, and EF-18 steers (P < 0.05), however, this difference was not observed on day 0 or 42 (P > 0.05). Based on these data, steers exposed to ergovaline have an increase in pro- and anti-inflammatory cytokines and supplemental CP had minimal impact to mitigate this response. However, in the current study, exposure to ergovaline had little to no effect on adaptive immunity and response to vaccination. Together, chronic exposure to ergovaline results in a hyperactive innate immune response, which may lead to an immuno-compromised animal.

Enhancing the adoption of stockpiling tall fescue and managed grazing.

One of the primary goals of extension is to encourage and support adoption of improved technologies. Managed grazing and stockpiling forage are two such technologies. The goal of this project was to encourage adoption of these practices by providing on-farm demonstrations of the technologies. We also collected forage and soil data and held workshops at each of the demonstration sites. Host producers were selected, given a basic kit of temporary fencing supplies for use during the demonstration, and instructed on their proper use during the winter stockpiling season. Forage yield and quality data were collected and soil tests made to show the economic advantages of proper fertilization and grazing fresh forage in contrast to feeding stored forage and concentrate. The nutritive value of the forage stockpiled in September through November (67% total digestible nutrients [TDN] and 14% crude protein, CP) exceeded the needs of the cattle and was greater than the nutrient content of hay present on the farms (59% TDN and 11% CP, P < 0.01). The mean quantity of available forage (2,856 ± 164 kg dry matter per hectare) provided an average of 260 (±81.8) standard cow (545 kg) grazing days per hectare of stockpiled forage. Taking into account the higher nutritive value of the fresh forage when compared with hay and the savings of time and equipment costs by grazing, we estimated that grazing stockpiled forage saved $1.28 per standard cow per day. The grazing management skills gained during this project and the temporary fencing technology were adopted by 93% of the demonstration farms that responded to our follow-up survey (78% of demonstration sites), and the area managed with these technologies increased on these sites more than 350%. Having the hosts share personal experiences played an important role in encouraging their peers to adopt the technologies.

Impact of energy restriction during late gestation on the muscle and blood transcriptome of beef calves after preconditioning.

BACKGROUND: Maternal nutrition has been highlighted as one of the main factors affecting intra-uterine environment. The increase in nutritional requirements by beef cows during late gestation can cause nutritional deficiency in the fetus and impact the fetal regulation of genes associated with myogenesis and immune response. METHODS: Forty days before the expected calving date, cows were assigned to one of two diets: 100% (control) or 70% (restricted group) of the daily energy requirement. Muscle samples were collected from 12 heifers and 12 steers, and blood samples were collected from 12 steers. The objective of this work was to identify and to assess the biological relevance of differentially expressed genes (DEG) in the skeletal muscle and blood of beef calves born from cows that experienced [or not] a 30% energy restriction during the last 40 days of gestation. RESULTS: A total of 160, 164, and 346 DEG (q-value< 0.05) were identified in the skeletal muscle for the effects of diet, sex, and diet-by-sex interaction, respectively. For blood, 452, 1392, and 155 DEG were identified for the effects of diet, time, and diet-by-time interaction, respectively. For skeletal muscle, results based on diet identified genes involved in muscle metabolism. In muscle, from the 10 most DEG down-regulated in the energy-restricted group (REST), we identified 5 genes associated with muscle metabolism and development: SLCO3A1, ATP6V0D1, SLC2A1, GPC4, and RASD2. In blood, among the 10 most DEG, we found genes related to response to stress up-regulated in the REST after weaning, such as SOD3 and INO80D, and to immune response down-regulated in the REST after vaccination, such as OASL, KLRF1, and LOC104968634. CONCLUSION: In conclusion, maternal energy restriction during late gestation may limit the expression of genes in the muscle and increase expression in the blood of calves. In addition, enrichment analysis showed that a short-term maternal energy restriction during pregnancy affects the expression of genes related to energy metabolism and muscle contraction, and immunity and stress response in the blood. Therefore, alterations in the intra-uterine environment can modify prenatal development with lasting consequences to adult life.

Effects of timing of vaccination relative to weaning and post-weaning frequency of energy supplementation on growth and immunity of beef calves.

A 2 × 2 factorial design study evaluated the impact of pre- vs. post-weaning vaccination and different post-weaning frequency of energy supplementation (daily vs. 3X weekly) on growth and immunity of beef calves. At 14 d before weaning (d -14), 48 Angus calves (24 steers and 24 heifers; 244 ± 33 kg; 196 ± 20 d) were stratified by BW and age, and randomly assigned to receive vaccinations against bovine viral diarrhea virus 1a (BVDV-1a) and parainfluenza-3 (PI-3) on d -14 and 0 (PRE) or 7 and 21 (POS), relative to weaning. Calves were weaned on d 0 and offered daily concentrate DM supplementation (50:50 soybean hulls and corn gluten feed; 71% TDN, 15% CP of DM) at 0.5% of BW for 7 d. On d 7, calves were stratified by vaccination scheme and assigned into 1 of 16 drylot pens (3 calves of same sex/pen; 4 pens/treatment). Pens were randomly assigned to receive similar weekly concentrate DM supplementation (1% of BW multiplied by 7 d) that was divided and offered daily (7X) or three times weekly (3X; Mondays, Wednesdays, and Fridays) from d 7 to 43. From d 0 to 43, calves were provided ad libitum ground tall fescue hay (57% TDN, 13% CP of DM). Blood samples were collected from jugular vein on d 0, 1, 3, 7, and 14, relative to the respective first vaccination, and on d 43 of the study. Effects of timing of vaccination × frequency of supplementation were not detected for any variable in this study (P ≥ 0.12), except for overall ADG from d -14 to 43 (P = 0.04), which was less for PRE-3X vs. PRE-7X, POS-3X, and POS-7X calves (0.60, 0.70, 0.70, and 0.77 ± 0.04 kg/d, respectively; P ≤ 0.08). Post-weaning total DMI and G:F did not differ among treatments (P ≥ 0.11). Pre-weaning vaccination increased plasma concentrations of cortisol and haptoglobin from d 0 to 3, relative to first vaccination (P ≤ 0.03), and decreased serum PI-3 titers on d 43 compared with post-weaning vaccination (P < 0.0001). Decreasing the supplementation frequency tended (P = 0.10) to increase overall plasma cortisol concentrations and reduce overall serum BVDV-1a titers. Hence, pre-weaning vaccination associated with reduced post-weaning frequency of energy supplementation caused the greatest reduction on calf growth performance. Post-weaning vaccination and daily energy supplementation alleviated inflammation and improved humoral immunity compared with pre-weaning vaccination and reduced post-weaning frequency of energy supplementation of recently weaned beef calves.

Physiological responses to known intake of ergot alkaloids by steers at environmental temperatures within or greater than their thermoneutral zone.

Two studies separated effects of dietary ergot alkaloids from effects of feed intake or ambient temperature on respiration rate (RR), heart rate (HR), surface temperature (ST), rectal temperature (RT), blood pressure (BP), serum hormone, and plasma metabolite concentrations in beef steers. The balanced, single reversal design for each experiment used 8 beef steers fed tall fescue seed [2.5 g/kg body weight (BW)] with (E+) or without (E-) ergot alkaloids as part of a 60:40 switchgrass hay: supplement diet. Periods were 35 days with 21 days of preliminary phase and 14 days of feeding fescue seed once daily. Measures of dependent variables were collected on d 20, 25, 29, and 35 of each period at 0730 (before feeding), 1230 and 1530. In Experiment 1 steers weighed 286 kg, gained 0.61 kg BW/day, E+ supplied 2.72 mg ergot alkaloids including 1.60 mg ergovaline per steer daily, and mean minimum and maximum daily ambient temperatures were 23.6 and 32.3°C. In Experiment 2 steers weighed 348 kg, gained 1.03 kg BW/day, E+ supplied 3.06 mg ergot alkaloids including 2.00 mg ergovaline daily, and mean minimum and maximum daily ambient temperatures were 11.9 and 17.4°C. Dry matter intake was not affected by fescue seed treatment (P < 0.20) in either experiment. In both experiments, E+ reduced HR (P < 0.01) and increased insulin (P = 0.07). Systolic BP minus diastolic BP decreased (P < 0.05) for E+ in both experiments, due to increased diastolic BP in Experiment 1 (P < 0.03) and decreased systolic BP in Experiment 2 (P < 0.07). In Experiment 1, above the thermoneutral zone, E+ increased (P < 0.05) RR, RT, and left side ST in comparison to E-, but in Experiment 2, within the thermoneutral zone, E+ and E- did not differ (P < 0.18). Ergot alkaloids from fescue seed affect the cardiovascular system of steers separately from effects of feed intake or environmental temperature. Ergot alkaloids interact with ambient temperatures above the steers' thermoneutral zone to exacerbate the symptoms of hyperthermic stress.

Analysis of nutrient concentrations in the diet, serum, and urine of giraffe from surveyed North American zoological institutions.

The objectives of the present research were to conduct a survey to investigate the health history and feeding practices of giraffe in captivity in North America and to obtain samples of hay, concentrate, browse, urine, and serum to compare across zoos, possible factors relating to the development of urolithiasis. Forty-one out of 98 institutions contacted responded, representing 218 giraffe. All responding zoos fed concentrate and alfalfa hay was the primary forage. Sixty-five percent of zoos fed browse and 43 different species of browse were listed. Six zoos reported a history of urolithiasis, seven reported wasting syndrome, and 10 reported sudden death. The median daily amount (as fed) of concentrate and hay offered were 5.45 kg (range of 2.73-9.55 kg) and 6.82 kg (range of 2.53-12.50 kg), respectively. The concentrate:hay ratio of the offered diet ranged from 0.22 to 3.47 with a median value of 0.79. Forty-three percent of the institutions offered a ratio greater than 1:1. Samples of concentrate and hay (six zoos), serum (five zoos), and urine (seven zoos) were obtained for chemical analyses. Analyzed nutrient content of the consumed diet, measured by weighing feed and orts for three consecutive days, met recommendations for giraffe, but was excessive for crude protein and P. Concentrate:hay and serum P were positively correlated (r=0.72; P<0.05). High dietary P content and a high level of concentrate relative to hay may be contributing factors to urolith formation and warrant further investigation.

Experimental infection of native north Carolina salamanders with Batrachochytrium dendrobatidis.

Chytridiomycosis is an often fatal fungal disease of amphibians caused by Batrachochytrium dendrobatidis. This disease has been implicated in the worldwide decline of many anuran species, but studies of chytridiomycosis in wild salamanders are limited. Between August 2006 and December 2006, we tested wild amphibians in North Carolina, USA (n=212) by polymerase chain reaction (PCR). We identified three PCR-positive animals: one Rana clamitans and two Plethodontid salamanders. We experimentally infected two species of native North Carolina Plethodontid salamanders, the slimy salamander (Plethodon glutinosus) and the Blue Ridge Mountain dusky salamander (Desmognathus orestes) with 1,000,000 zoospores of B. dendrobatidis per animal. Susceptibility was species dependent; all slimy salamanders developed clinical signs of chytridiomycosis, and one died, whereas dusky salamanders remained unaffected. In a second experiment, we challenged naïve slimy salamanders with either 10,000 or 100,000 motile zoospores per animal. Clinical signs consistent with chytridiomycosis were not observed at either dose or in uninfected controls during the 45 days of this experiment. All animals inoculated with B. dendrobatidis in both experiments, regardless of dose, tested positive by PCR. Our study indicates that slimy salamanders are more susceptible to clinical chytridiomycosis than dusky salamanders, and in a laboratory setting, a dose greater than 100,000 zoospores per animal is required to induce clinical disease. This study also indicates that PCR is a very sensitive tool for detecting B. dendrobatidis infection, even in animals that are clinically unaffected, thus positive results should be interpreted with caution.

The use of resorbable hardware for fixation of pediatric mandible fracture. Case report.

The diagnosis and management of mandible fractures in the pediatric patient population can pose multiple challenges to the oral and maxillofacial surgeon. Resorbable plates and screws for fixation in this population are both well tolerated and effective. They enable realignment and stable positioning of rapidly healing fracture segments, while obviating any potential impediments to long-term metal retention.

Efficacy of tinidazole for treatment of cats experimentally infected with Tritrichomonas foetus.

OBJECTIVE: To determine the efficacy of tinidazole for treatment of cats with experimentally induced Tritrichomonas foetus infection. ANIMALS: 8 specific-pathogen-free kittens. PROCEDURES: Tinidazole was tested for activity against a feline isolate of T foetus in vitro. Kittens were infected orogastrically with the same isolate and treated or not with tinidazole (30 mg/kg, PO, q 24 h for 14 days). Amoxicillin was administered 28 weeks after completion of tinidazole administration to induce diarrhea. Feces were repeatedly tested for T foetus by use of PCR assay and microbial culture for 33 weeks. RESULTS: Tinidazole killed T foetus at concentrations >or= 10 microg/mL in vitro. In experimentally induced infection, tinidazole administered at 30 mg/kg decreased T foetus below the limit of molecular detection in 2 of 4 cats. Recrudescent shedding of T foetus, as elicited by amoxicillin-induced diarrhea, was diminished in cats that received prior treatment with tinidazole. CONCLUSIONS AND CLINICAL RELEVANCE: Although tinidazole decreased the detection of T foetus and treated cats were resistant to later efforts to incite the infection, inability of tinidazole to eradicate infection in many cats poses a serious impediment to the drug's effectiveness in practice.

A highly specific PCR assay for detecting the fish ectoparasite Amyloodinium ocellatum.

Amyloodiniosis, caused by the dinoflagellate ectoparasite Amyloodinium ocellatum, is one of the most serious diseases affecting marine fish in warm and temperate waters. Current diagnostic methods rely entirely on the microscopic identification of parasites on the skin or gills of infested fish. However, subclinical infestations usually go undetected, while no method of detecting the free-swimming, infective (dinospore) stage has been devised. Targeting the parasite's ribosomal DNA region, we have developed a sensitive and specific PCR assay that can detect as little as a single cell from any of the 3 stages of the parasite's life cycle (trophont, tomont, dinospore). This assay performs equally well in a simple artificial seawater medium and in natural seawater containing a plankton community assemblage. The assay is also not inhibited by gill tissue. Sequence analysis of the internal transcribed spacer region of 5 A. ocellatum isolates, obtained from fish in the Red Sea (Israel), eastern Mediterranean Sea (Israel), Adriatic Sea (Italy), Gulf of Mexico (Florida), and from an unknown origin, revealed insignificant variation, indicating that all isolates were the same species. However, 3 of these isolates propagated in cell culture varied in behavior and morphology, and these differences were consistent during at least 2 yr in culture. Thus, our findings do not eliminate the possibility that different strains are in fact 'subspecies' or lower taxa, which may also differ in pathogenic and immunogenic characteristics, environmental tolerance, and other features.

Ground cover impacts on nitrogen export from manured riparian pasture.

Maintaining ground cover of forages may reduce the export of nitrogen (N) from pastures. The objective of this work was to determine the effect of ground cover on N export from pastured riparian areas receiving simulated rainfall. Plots were established on two adjacent sites in the North Carolina Piedmont: one of 10% slope with Appling sandy loam soils and a second of 20% slope with Wedowee sandy loam soils. Both sites had existing mixed tall fescue (Festuca arundinacea Schreb.)-dallisgrass (Paspalum dilatatum Poir.) vegetation. Forage stands were modified to represent a range of ground cover levels: 0, 45, 70, and 95% (bare ground, low, medium, and high cover, respectively), and amended with beef steer (Bos taurus) feces and urine (approximately 200 kg N ha-1). For all rain events combined, mean nitrate N export was greatest from bare ground and was reduced by 34% at low cover, which did not differ from high cover. Mean ammonium N export was slightly elevated (approximately 1.37 kg N ha-1) in months when manures were applied and negligible (<0.02 kg N ha-1) in all other months. For all rain events combined, mean export of total N was greatest from bare ground and was reduced by at least 85% at all other cover levels. Whereas site did not impact N export, results indicated that cover and time of rainfall following manure deposition are important determinants of the impact of riparian grazing.

Effect of stacking method on Salmonella elimination from recycled poultry bedding.

Recycled poultry bedding (RPB) is a protein and mineral supplement for cattle. Concerns regarding this product have arisen because of the perceived risk of transmitting potentially pathogenic organisms to cattle. This study's primary objective was to assess survival of Salmonella in RPB stacked to a recommended height (2.13 m-DS-RPB), or a height of 0.76 m (SS-RPB). Dialysis bags containing RPB and Salmonella typhimurium were placed throughout stacks. Temperature was monitored daily using thermocouples attached to sample bags. After 21 days, sample bags were recovered. Ammonia analysis was performed from multiple sites in the stacks. Bag contents were cultured to determine viability of the salmonella inoculates. This trial demonstrated a wide variation of temperature within the stacks. Temperature near the edge of stacks changed with ambient temperature. Ammonia concentration in the RPB was highest at the top of the DS-RPB. Salmonella was eliminated in 98.7% of sites, with at least a 5-log reduction in the Salmonella organisms in sites where it was still viable.

Ground cover impacts on sediment and phosphorus export from manured riparian pasture.

Maintaining pasture ground cover is important in preventing environmental degradation of grasslands and associated riparian areas. The objective of this work was to determine the effect of ground cover on sediment and P export from pastured riparian areas under simulated rainfall events. Plots were established on two sites in the North Carolina Piedmont: a 10% slope with Appling sandy loam soils (fine, kaolinitic, thermic Typic Kanhapludults) and a 20% slope with Wedowee sandy loam soils (fine, kaolinitic, thermic Typic Kanhapludults), both with mixed tall fescue (Festuca arundinacea Schreb.)-dallisgrass (Paspalum dilatatum Poir.) vegetation. Existing forage stands were modified to represent a range of ground cover levels: 0, 45, 70, and 95% (bare ground, low, medium, and high cover, respectively), and amended with beef steer (Bos taurus) feces and urine (about 10 kg P ha(-1)). Mean runoff volume from bare ground was generally twice that observed from low, medium, and high levels of cover, which were similar. For all rainfall events combined, export of dissolved reactive P was greatest (P < 0.1) at bare ground and was reduced 31% at low cover, which did not differ from medium or high cover. Mean total Kjeldahl P export was greater (P < 0.001) from bare ground than from other cover levels. Results indicate that riparian bare areas can contribute substantial sediment (>215 kg ha(-1)) and P (0.7 kg P ha(-1)) to surface waters during heavy rainfall, whereas export may be reduced equally well by low cover (45%) as by high cover.

Efficacy of ronidazole for treatment of feline Tritrichomonas foetus infection.

OBJECTIVES: To determine the efficacy of ronidazole (RDZ), tinidazole (TDZ), and metronidazole (MDZ) against Tritrichomonas foetus in vitro and of RDZ for treatment of feline naturally occurring or experimentally induced T. foetus infection. ANIMALS: A cat naturally infected with T. foetus infection and diarrhea. Ten specific-pathogen-free (SPF) kittens. PROCEDURE: RDZ, TDZ, and MDZ were tested for activity against 3 different feline isolates of T. foetus in vitro. RDZ then was administered to a naturally infected cat at 10 mg/kg PO q24h for 10 days. SPF kittens were infected orogastrically with feline T. foetus and treated with either placebo or RDZ (10 mg/kg PO q12h for 14 days). Cats with relapsing infection or those receiving placebo were treated subsequently with RDZ (either 30 or 50 mg/kg PO q12h for 14 days). Feces were examined for T. foetus by direct microscopy, culture, and polymerase chain reaction (PCR) testing weekly. RESULTS: Both RDZ and TDZ killed T. foetus at concentrations >0.1 microg/mL in vitro. In the naturally infected cat, RDZ abolished diarrhea and T. foetus infection for 85 days after treatment, at which time infection and diarrhea relapsed. Retreatment with RDZ eradicated diarrhea and T. foetus infection for over 407 days. In experimentally induced infection, RDZ at 10 mg/kg caused initial improvement, but infection relapsed in all 5 cats 2 to 20 weeks after treatment. At 30 or 50 mg/kg, 10/10 cats were negative for T. foetus infection for follow-up durations of 21 to 30 weeks after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Oral administration of RDZ at 30 to 50 mg/kg q12h for 14 days resolved diarrhea and eradicated infection (on the basis of polymerase chain reaction [PCR] testing) in 1 naturally infected cat and 10 experimentally inoculated cats receiving a different isolate of T. foetus.

Outcome of cats with diarrhea and Tritrichomonas foetus infection.

OBJECTIVE: To determine the long-term outcome of cats infected with Tritrichomonas foetus and identify treatment and management strategies influencing resolution of infection or associated diarrhea. DESIGN: Prospective study. SAMPLE POPULATION: 26 cats with T. foetus-associated diarrhea at least 22 months prior to the study. PROCEDURE: A standardized survey regarding clinical course and management was administered to owners of cats with T. foetus infection and associated diarrhea. Fecal samples were obtained from each cat; the presence of T. foetus was assessed via microscopic examination of smears, culture in commercial media, and polymerase chain reaction amplification of T. foetus rDNA involving species-specific primers. RESULTS: Survey responses were obtained from owners of all 26 cats. Twenty-three cats had complete resolution of diarrhea a median of 9 months after onset. Analysis of fecal samples obtained from 22 cats revealed persistent T. foetus infection in 12, with a median of 39 months after resolution of diarrhea. History of implementation of a dietary change, treatment with paromomycin, or higher numbers of cats in the household was associated with significantly longer duration of time to resolution of diarrhea. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested chronic T. foetus-associated diarrhea in most cats is likely to resolve spontaneously within 2 years of onset. Chronic infection with T. foetus (without clinical signs) after resolution of diarrhea appears to be common. Although often temporarily effective in decreasing severity of diarrhea, attempts to treat cats with T. foetus infection may result in prolongation of time to resolution of diarrhea.