Prevalence of Vibrio parahaemolyticus, and Vibrio vulnificus in blue crabs (Callinectes sapidus), seawater and sediments of the Maryland Coastal Bays.

AIMS: To determine the prevalence of total and pathogenic Vibrio parahaemolyticus (Vp) and V. vulnificus (Vv) in blue crabs, water and sediment from the Maryland Coastal Bays (MCBs), USA. METHODS AND RESULTS: Crab, haemolymph, sediment and seawater samples were collected monthly from four sites in MCBs from February 2012 through October 2012 with environmental parameters recorded. The most-probable-number (MPN) methodology was used to enumerate Vp and Vv with presumptive colonies and the presence of virulence markers confirmed using polymerase chain reaction (PCR). Results indicate that blue crabs contained both Vp and Vv at densities (7·28 and 5·43 log MPN g(-1) , respectively) higher than those reported for bivalves. In addition, markers for clinically relevant strains of both species were detected in over 30% of samples. Haemolymph, sediment and seawater samples were also routinely positive for both species and clinically relevant strains, but generally at lower densities than found in crabs (4·27, 3·28, and 2·39 log MPN g(-1) per ml(-1) Vp, and 4·28, 2·49 and 2·38 log MPN g(-1) per ml(-1) Vv). CONCLUSIONS: Blue crabs concentrate Vp and Vv at levels greater than found in water or sediment. While changes in abundance associated with temperature are apparent, there is little evidence to support differences among sampling locations. SIGNIFICANCE AND IMPACT OF THE STUDY: These results highlight the potential for blue crab related vibriosis and the importance of proper handling, cooking and care of this popular seafood before consumption.

Growth performance and adipose tissue deposition in barrows fed n-methyl-D,L-aspartate.

We previously reported that broilers fed n-methyl-D,L-aspartate (NMA) exhibited enhanced feed conversion efficiency and decreased percentage of fat in carcasses. In this experiment, growth performance and backfat thickness were evaluated in barrows fed NMA. Poland China x Yorkshire barrows weighing 68.8 +/- 1.7 kg (mean +/- SE) were allowed ad libitum access to feed containing NMA at levels of either 0 (n = 7), 100 (n = 6), 200 (n = 8), or 300 (n = 8) mg/kg for 36 d. Barrows were slaughtered at 99.5 +/- 2.3 kg BW. There was no effect (P > 0.1) of NMA on ADG or feed consumption. Gain:feed ratio decreased (P < 0.03) in a linear fashion with increasing level of NMA. There was a cubic effect (P < 0.05) of NMA treatment on first-rib backfat thickness. In response to graded levels of NMA, backfat thickness at the 10th rib (P < 0.08) and last rib (P < 0.03) increased in a linear fashion. The NMA had no effect (P > 0.1) on backfat thickness measured at the lumbar vertebra or longissimus muscle area measured at the 10th rib interface. The percentage of lean in the carcass decreased in a linear fashion (P < 0.05) in response to increasing levels of NMA in the diet. In summary, NMA had an overall negative effect on growth performance and carcass yield characteristics in barrows. The dichotomous effects of NMA on feed efficiency and body composition in poultry and swine warrants further scrutiny.

Risk factors associated with early respiratory disease complex in broiler chickens.

Early respiratory disease complex (ERDC) is a term coined to describe an acute disease characterized by depression, respiratory distress, and increased mortality in 2-to-3-wk-old broiler chickens. Postmortem lesions include airsacculitis, fibrinous pericarditis, and perihepatitis. Colisepticemia is the primary cause of death. In order to investigate the association between ERDC and farm management factors, a retrospective case-control study was conducted by collecting data covering a 6-mo period (January-June 1997) from four broiler integrators on the Delmarva peninsula. Univariate and multivariate statistical analyses revealed that flock size was positively associated (P = 0.02) and layout time was negatively associated (P = 0.05) with ERDC.

Role of neuropeptides and amino acids in controlling secretion of hormones from the anterior pituitary gland in pigs.

All reproductive processes involve one or more of the protein hormones secreted from the anterior pituitary gland: LH, FSH, prolactin, growth hormone, ACTH and thyroid-stimulating hormone (TSH). Primary hormones of reproduction, such as LH and FSH, directly regulate a reproductive activity. For example, LH and FSH stimulate follicular growth and the associated secretion of oestradiol in sows. In contrast, secondary hormones of reproduction such as TSH are permissive and regulate other physiological systems that indirectly, but profoundly, influence reproduction. Reproduction in pigs can be enhanced by developing strategies to alter and control secretion of hormones from the anterior pituitary gland. However, the successful manipulation of adenohypophysial hormone secretion will require a sound understanding of the mechanisms controlling the function of the hypothalamic-pituitary axis. Hypothalamic hormones including GnRH, dopamine, growth hormone-releasing hormone (GHRH), somatostatin, corticotrophin-releasing hormone (CRH) and thyrotrophin-releasing hormone (TRH) are synthesized in perikarya that possess axons that terminate at the median eminence. These hormones are released into the hypothalamo-hypophysial portal vasculature, travel to the anterior pituitary gland and stimulate or inhibit secretion of adenohypophysial hormones. Secretion of hypothalamic hormones is ultimately controlled by a variety of neurotransmitters and neuropeptides, the most studied in swine being the endogenous opioid peptides (EOP) and more recently, the excitatory amino acids (ExAA). In general, EOP inhibit GnRH and hence LH secretion, and this effect involves the central catecholaminergic system. A definitive role for EOP in the modulation of FSH release remains to be determined. EOP stimulate secretion of GHRH and thus growth hormone release, and depending on the animal model studied, EOP exert either stimulatory or inhibitory influences on prolactin secretion. ExAA, working via N-methyl-D-aspartate (NMDA) receptors at the central nervous system, stimulate secretion of LH, FSH, growth hormone and prolactin in appropriate animal models. However, in certain situations, an inhibitory effect of ExAA on LH secretion has been demonstrated. The modulation of growth hormone and prolactin secretion by ExAA involves EOP. Research investigating the function of ExAA and EOP in the physiological control of swine reproduction warrants further scrutiny.

N-methyl-D,L-aspartate-induced growth hormone secretion in barrows: possible mechanisms of action.

Four experiments were conducted to determine mechanisms by which n-methyl-d,l-aspartate (NMA) increases serum concentrations of growth hormone (GH). Blood samples were collected from barrows every 15 min for 2 h (Exp. 1, 2, and 3) or 3 h (Exp. 4) immediately before and immediately after i.v. treatments. In Exp. 1, barrows (n = 4/treatment) received either .9% saline or 1.25, 2.5, or 5 mg of NMA/kg of BW. The change in circulating GH concentrations was greater (P < .05) for barrows receiving 2.5 mg (by 883%) or 5.0 mg of NMA/kg of BW (by 1,095%) than for those injected with saline. In Exp. 2, barrows (n = 4/treatment) received NMA (2.5 mg/kg of BW) or injections of 1.25 mg of the pure d or pure 1 isomers of NMA/kg of BW. Growth hormone concentrations increased by 177% (P < .025) after NMA treatment and by 245% (P < .01) after injection of the pure d isomer of NMA. The pure 1 isomer of NMA had no effect (P > .1) on GH concentrations. In Exp. 3, barrows received NMA (2.5 mg/kg of BW) 10 min after i.m. injection of saline (n = 7) or ketamine hydrochloride ( n = 8; 19.9 mg/kg of BW), an n-methyl-d-aspartate (NMDA) receptor antagonist. The NMA increased (P < .01) GH concentrations by 289% in saline-pretreated barrows but had no effect (P > .1) on barrows pretreated with ketamine hydrochloride. In Exp. 4, barrows (n = 4/treatment) received NMA 3 h after i.v. pretreatment with antisera to GH-releasing factor (GRF; 154 mL) or no pretreatment. Serum GH concentrations increased by 166% (P < .05) after injection of NMA in barrows receiving no pretreatment. The NMA had no effect (P > .1) on GH concentrations in barrows receiving antisera to GRF. Our results support the concept that NMDA stimulates GRF, and hence GH secretion, by activating an NMDA receptor.

Luteinizing hormone and growth hormone concentrations in serum of prepubertal gilts treated with N-methyl-D,L-aspartate.

Prepubertal Yorkshire gilts, 189 d of age and 96 kg body weight (BW), were used to determine the effects of intravenous injections of N-methyl-D,L-aspartate (NMA) on circulating concentrations of luteinizing hormone (LH) and growth hormone (GH). In Experiment 1, blood was sampled from four gilts every 15 min for 2 hr on four consecutive days. One hour after the initiation of sampling on each day, gilts received either vehicle (0.9% saline solution) or 1.25, 2.5, or 5 mg of NMA/kg BW as per a 4 x 4 latin square arrangement of treatments. There was no effect of treatment (P > 0.1) on concentrations of LH in serum. However, relative to vehicle-treated animals, gilts administered 2.5 mg of NMA/kg BW had elevated (1,120%; P < 0.05) circulating levels of GH. In Experiment 2, samples were collected from 15 gilts at 15-min intervals for 1 hr before and 1 hr after NMA (10 mg/kg BW; n = 8) or vehicle (n = 7). NMA increased serum concentrations of both LH (by 80%; P < 0.05) and GH (by 700%; P < 0.01). We suggest that LH and GH secretion in gilts was enhanced by treatment with NMA.

The effect of feed restriction and Eimeria maxima infection with or without medication on growth and feed intake in broilers.

Day-old male broiler chicks were raised in floor pens. At 4 days of age, birds in 75% of the pens were inoculated with Eimeria maxima via the feed. There were four dietary treatments: uninoculated, unmedicated control (UUC), infected, unmedicated control (IUC), infected, halofuginone-medicated (3 ppm, HM), or infected, salinomycin-medicated (66 ppm, SM). At 6 days of age, birds in 50% of the pens of each treatment were restricted for 5 days to their maintenance energy intake level. The remainder consumed feed ad libitum. Medication reduced growth from 0 to 6 days of age and feed intake was depressed, irrespective of medication, in infected birds from 0 to 21 days of age. Growth, however, was improved with intake of coccidiostat over IUC from 6 to 11 days of age but did not match UUC until 28 days of age. At 42 and 49 days of age, infected birds were lighter than UUC birds. Dressing percentage for HM and SM birds was greater than that of UUC birds at 49 days of age but HM birds also had a greater percentage of abdominal fat at both 42 and 49 days of age. Feed restriction resulted in some compensatory growth immediately following refeeding. Experimental feed:gain ratio was improved in restricted birds (1.98 versus 2.03 g:g). At 42 and 49 days of age, restricted birds were lighter than birds eating ad libitum and also had a significantly greater percentage abdominal fat. A lower breast yield was observed at 42 days of age in restricted birds.

The effect of increasing photoperiod and food restriction in sexed broiler-type birds. I. Growth and abdominal fat cellularity.

1. Sexed broiler-type chicks were raised either under a continuous (CON) 23 h Light (L) and 1 h Dark (D) schedule or an increasing photoperiod (INC) consisting of an initial 6 h L and 18 h D which increased by 4 h L per week from 14 to 35 d of age after which a 23 L:1D was maintained to 49 d of age. 2. From 5 to 11 d of age birds were fed either: ad libitum (AL), energy intake (kJ ME) restricted to 9.414 x gBW0.67 (R1) or energy intake (kJ ME) restricted to 6.276 x gBW0.67 (R2). Food intake was ad libitum at all other times. 3. Food restriction reduced growth to 49 d of age although some compensatory growth did occur. Food efficiency was not significantly affected by restriction. 4. Although abdominal fat pad weight was significantly reduced for R2 compared to AL, this was not significant on a percentage body weight basis. 5. Adipocyte number in the abdominal fat pad was similar for AL, R1 and R2, but concomitant with a smaller fat pad weight, R2 showed reduced adipocyte volume compared to AL. 6. INC birds were lighter at 21 d of age, but body weights were equivalent to CON by 42 d of age. 7. Abdominal fat pad weight was some 10% larger at 49 d of age for INC birds. Adipocyte volume was unaffected, the increase in adipocyte being entirely caused by an increase in adipocyte number in INC birds.

The effect of increasing photoperiod and food restriction in sexed, broiler-type birds. II. Plasma thyroxine, triiodothyronine, insulin-like growth factor-I and insulin.

1. Sexed broiler-type chicks were raised either under a continuous (CON) 23 h light (L) and 1 h dark (D) schedule or an increasing photoperiod (INC). From 5 to 11 d of age birds were fed either: ad libitum (AL), energy intake (kJ ME) restricted to 9.414 x gBW0.67 (R1) or energy intake (kJ ME) restricted to 6.276 x gBW0.67 (R2). 2. Blood samples were taken at 4, 7, 11, 14 d of age and weekly thereafter to 49 d of age. Plasma thyroxine (T4), triiodothyronine (T3), insulin-like growth factor-I (IGF-I) and insulin were determined. 3. CON birds had elevated plasma T3 concentrations to 21 d of age, and greater plasma T4 concentrations at 11 and 21 d of age concurrent with greater food intake. Elevated plasma T3 concentrations in INC birds at 28 d of age coincided with lower plasma IGF-I concentrations at a time when growth and food intake were greater than CON birds. 4. Food restriction elevated plasma insulin and T4 but depressed plasma T3 and IGF-I. Plasma T3 was greater for food-restricted birds at 21 d of age, but subsequently, was generally lower than ad libitum-fed birds which may account for a lack of complete 'catch-up' in growth. 5. Plasma T3 was higher in females at 11 d of age when growth was equivalent for both sexes. From 28 to 42 d, when sex differences in growth became most apparent, plasma T3 was greater in males.

Effects of ferrous sulfate consumption on the performance of broiler chicks.

Ferrous sulfate is often used as a litter treatment to control ammonia. A series of experiments was conducted to evaluate the effects of single high and multiple low doses of ferrous sulfate (FeSO4-7H2O) on broiler chicks. In Experiment 1, broiler chicks were administered a single oral dose of ferrous sulfate. A direct relationship between mortality and the amount of ferrous sulfate administered was evident. The lethal dose that caused 50% mortality (LD50) for ferrous sulfate was calculated to be 7,010 mg/kg of body weight. In Experiment 2, the addition of ferrous sulfate to the diet at levels from .75 to 12% decreased feed consumption. Ferrous sulfate levels of 3% or greater lowered average daily gain and gain:feed ratios. In a pair-wise comparison preference test in Experiment 3, chicks significantly decreased consumption of a diet containing 3% ferrous sulfate but not of a diet with .375% ferrous sulfate. The results of these experiments indicate that ferrous sulfate can have adverse effects on mortality, weight gain, and feed efficiency of broiler chicks.

Development of a quantitative method for the evaluation of varus-angular bone deformity in chickens.

A quantitative technique was developed to measure the degree of flexion (twisting) and torsion (angulation) of the tibiotarsus bone from chickens affected with varus-angular bone deformity (varus-ABD). A plexiglass device was constructed consisting of X, Y, and Z-axis planes. The Y-axis plane was used to position the tibia in a constant reference position. The distance in millimeters from the (0, 0, 0) coordinate to the (X', 0, 0) coordinate was used to measure medial tibial flexion (TF), and the distance from the (0, 0, 5 cm) coordinate to the (X', 0, 5 cm) coordinate was used to measure lateral TF. The X-axis plane was fitted with a protractor to measure the angle of the proximal head of the tibia as a measure of tibial torsion (TT). The Z-axis plane was used to measure tibial length. Tibias with mild varus-ABD had TF values of greater than 0 but less than or equal to 5 mm, whereas severe varus-ABD tibias had TF values of greater than 5 mm. The TT values ranged from 10 to 60 degrees, with the lower values associated with severe varus-ABD.