Detection and characterization of leptospiral antigens using a biotin/avidin double-antibody sandwich enzyme-linked immunosorbent assay and immunoblot.

A biotin/avidin double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of antigens of Leptospira interrogans serovars in experimentally inoculated bovine urine samples was evaluated. Immunoglobulin G (IgG) from rabbits immunized with L. interrogans serovar hardjo type hardjobovis sonicated, whole cell, and formalinized-heated antigen preparations were purified by a protein A-superose column coupled to fast protein liquid chromatography, and evaluated for species specificity in the ELISA. The ELISA using each specific IgG detected as few as 10(4) leptospires of the homologous serovar hardjo diluted in phosphate-buffered saline solution with Tween 20 (PBSS-Tween 20). On immunoblot analysis of proteinase-K-digested whole cell leptospiral preparations, each IgG revealed the presence of bands specific to serovar hardjo, suggesting the presence of serovar-specific epitopes on the lipopolysaccharide molecules. The minimum number of cells of heterologous serovars pomona, grippotyphosa, bratislava, icterohaemorrhagiae and copenhageni detected by each ELISA was greater, ranging from 10(6) to 10(7). The common antigenic determinants observed on immunoblot analysis were different for each specific IgG, except for a major cross-reacting, possibly flagellar, protein doublet at approximately 36-36.5 kDa. Leptospires were equally well detected by the ELISA in both bovine urine and PBSS-Tween 20.     

Movement patterns of Brook Trout in a restored coastal stream system in southern Massachusetts

Coastal Brook Trout (Salvelinus fontinalis) populations are found from northern Canada to New England. The extent of anadromy generally decreases with latitude, but the ecology and movements of more southern populations are poorly understood. We conducted a 33‐month acoustic telemetry study of Brook Trout in Red Brook, MA, and adjacent Buttermilk Bay (marine system) using 16 fixed acoustic receivers and surgically implanting acoustic transmitters in 84 individuals. Tagged Brook Trout used the stream, estuary (50% of individuals) and bay (10% of individuals). Movements into full sea water were brief when occurring. GAMM models revealed that transitions between habitat areas occurred most often in spring and fall. Environmental data suggest that use of the saline environment is limited by summer temperatures in the bay. Movements may also be related to moon phase. Compared to more northern coastal populations of Brook Trout, the Red Brook population appears to be less anadromous overall, yet the estuarine segment of the system may have considerable ecological importance as a food resource.     

Serotyping of Actinobacillus pleuropneumoniae serotype 5 strains using a monoclonal-based polystyrene agglutination test.

A polystyrene agglutination test has been developed for serotyping Actinobacillus pleuropneumoniae serotype 5a and 5b strains. Protein A-coated polystyrene microparticles were sensitized with a murine monoclonal antibody recognizing an epitope on serotype 5 LPS-O chain as shown by SDS-PAGE and Western blotting. A total of 205 A. pleuropneumoniae, strains including all 12 serotype reference strains and 13 strains representing 8 common bacterial species associated with swine or related to A. pleuropneumoniae, were tested by mixing 25 microL of polystyrene reagent with the same volume of a dense suspension of bacterial cells grown for 18 h. All A. pleuropneumoniae strains had been previously serotyped using standard procedures. The polystyrene agglutination test was rapid (less than 3 min) and easy to perform. Overall a very good correlation (97.3%) with the standard techniques was found. The sensitized polystyrene particles were stable for at least 6 mo.     

Immune function of bovine leukocytes after in vitro exposure to selected heavy metals

OBJECTIVE: To study effects of in vitro exposure of bovine leukocytes to mercury, cadmium, and lead on phagocytosis, natural killer cell activity, and lymphocyte proliferation. SAMPLE POPULATION: Leukocytes from 6 nonpregnant Holstein heifers. PROCEDURE: Leukocytes were exposed in vitro to the aforementioned metals, and leukocyte functions were assessed. RESULTS: Phagocytosis was suppressed by 10(-5) to 10(-7) M CdCl2 and by 10(-5) and 10(-6) M HgCl2, but not 10(-7) M HgCl2 nor 10(-4) to 10(-6) M PbCl2. Spontaneous and concanavalin A- or phytohemagglutinin-stimulated proliferation of metal-treated bovine blood mononuclear cells was not significantly different from that of nontreated control cells, except for enhanced spontaneous proliferation in response to 10(-5) M HgCl2. When proliferation was expressed as a stimulation index, a dose-dependent increase of spontaneous proliferation was observed in response to exposure to HgCl2 and PbCl2. Compared with response to 10(-6) or 10(-7) M CdCl2, reduction of mitogen-induced and spontaneous proliferation was observed on exposure to 10(-5) M CdCl2. Natural killer cell activity against YAC-1 target cells, evaluated by flow cytometry, was decreased only in cells exposed to 10 M HgCl2. CONCLUSION AND CLINICAL RELEVANCE: Bovine leukocytes are susceptible to the immunomodulatory effects of in vitro exposure to heavy metals at concentrations equal to or higher than those at which similar effects are seen for leukocytes from most other animal species for which data are available for comparison. Exception is phagocytosis, which is severely affected by low concentrations of CdCl2 and HgCl2 in cattle. Reduction of defense mechanisms on exposure to metals could lead to increased susceptibility to potential pathogens.     

The effect of feed intake level on splanchnic metabolism in growing beef steers

The effect of feed intake level (.6, 1.0, and 1.6 x maintenance energy and protein requirements, M) on splanchnic (portal-drained viscera [PDV] plus liver) metabolism was evaluated in six multicatheterized beef steers (398 +/- 27 kg), using a double 3 x 3 Latin square design. On the last day of each 21-d experimental period, six hourly blood samples were collected from arterial, portal, and hepatic vessels. Due to catheter patency, PDV fluxes were measured on five steers, and liver and splanchnic fluxes on four steers. Increasing intake elevated (P < .01) splanchnic release of total (T) amino acids (AA), through increases (P < .01) in PDV release of both essential (E) and nonessential (NE) AA, in spite of a tendency (P < .20) for increased liver removal of NEAA. The PDV release of AA N represented 27 and 51% of digested N for 1.0 and 1.6 x M, respectively. At 1.0 and 1.6 x M, the liver removed 34% of total AA released by the PDV. For individual AA, portal flux of most EAA increased (P < .05) with feed intake, and the increase (P < .10) in splanchnic flux was accompanied by increased arterial concentration for all EAA except histidine, lysine, and methionine. This suggests that these might be limiting AA for this diet. On a net basis, most individual NEAA were released by the PDV except glutamate and glutamine, which were removed by the digestive tract. There was a net removal of NEAA by the liver, except for aspartate and especially glutamate, which were released. Ammonia release by the PDV tended (P < .20) to increase with intake and represented 69, 53, and 45% of digested N at .6, 1.0, and 1.6 x M, respectively. Urea removed by the PDV, unaffected by intake, represented 32, 33, and 21% of the digested N. Arterial glucose concentration increased linearly (P < .01) with greater intake, whereas net liver and splanchnic glucose release increased in a quadratic (P < .05) manner. Net PDV glucose release represented 26% of net glucose hepatic release at 1.6 x M. Intake elevated (P < .10) both insulin and glucagon arterial concentrations, resulting from a larger increment of portal release (P < .01) than hepatic removal (P < .05). Intake-based variations in IGF-I and NEFA arterial concentrations (P < .05) were not related to changes in splanchnic metabolism. These results clearly show the crucial role of the splanchnic tissues in regulating the profile and quantity of AA and concentrations of glucose and pancreatic hormones reaching peripheral tissues.     

Insulin-like growth factor-I concentration in Holstein female cattle: variations with age, stage of lactation and growth hormone-releasing factor administration

Plasma insulin-like growth factor-I (IGF-I) concentrations were monitored in Holstein females through different periods of their growth, lactation and after acute or chronic growth hormone-releasing factor (GRF) administration. Plasma samples were radioimmunoassayed using a human IGF-I antibody after a 24 hr incubation in a HCl(.1N)-glycine(.2M) buffer (pH 2). In a first study, IGF-I concentrations were measured in Holstein females of different ages and(or) stages of lactation (n = 6 per group). The IGF-I concentrations in newborn calves (102.0 +/- 11.3 ng/ml) markedly decreased (P less than .01) in 1 mo old animals (50.2 +/- 7.1 ng/ml), then increased (P less than .01) to 137.0 +/- 5.1 and 137.4 +/- 11.0 ng/ml in 6 and 10 mo old heifers, respectively. In dairy cows, IGF-I concentrations were low 24 hr post-partum (44.7 +/- 7.6 ng/ml) and then increased (P less than .05) to remain stable throughout lactation (91.3 +/- 4.9, 92.8 +/- 12.9, 96.1 +/- 7.6, 90.7 +/- 8.8 ng/ml at 2, 3, 6 and 9 mo of lactation, respectively). There was a further increase (P less than .05) to 113.7 +/- 3.1 ng/ml during the dry period. In a second trial, blood samples were collected from lactating dairy cows every 2 hr for 24 hr following a sc injection of saline (n = 4) or human (h) GRF (1-29)NH2 (10 micrograms/kg BW, n = 4). The IGF-I peak concentration was reached on average 10 hr after the GRF injection and was higher (P less than .01) in treated cows than in control cows (135.4 vs 86.9 +/- 16.2 ng/ml). In the last trial, daily sc injections of 10 micrograms of hGRF(1-29)NH2 per kg BW to dairy cows (252 days of lactation) for 57 days, which increased milk production by 14% (2 kg/day), also increased (P less than .01) IGF-I concentration: 127.1 +/- 5.3 and 118.0 +/- 1.6 vs 90.7 +/- 4.7 and 96.0 +/- 5.0 ng/ml on days 29 and 57 of treatment for treated (n = 9) and control (n = 8) cows, respectively. Thus, the IGF-I concentration in dairy cattle varies with age and stage of lactation, and is increased by GRF administration in lactating dairy cows.     

Biochemistry reference values for Quebec lactating dairy cows, nursing sows, growing pigs and calves.

Reference values for lactating dairy cows, nursing sows, growing calves and pigs were established on jugular cannulated animals. On each day of sampling, 13 samples were taken every hour from dairy cattle, growing calves and pigs and 5 samples were taken every 2 h from nursing sows to minimize day and analysis bias. Results show that aging influences more biochemical factors in pigs than in calves, and in nursing sows variations observed between day 5 and 15 after farrowing are of greater amplitude than between day 15 and 25.     

Effect of human growth hormone-releasing factor and(or) thyrotropin-releasing factor on growth, carcass composition, diet digestibility, nutrient balance, and plasma constituents in dairy calves

Sixty male dairy grain-fed calves, raised from 70 to 223 kg BW in individual crates, were used in a 2 X 2 factorial arrangement to determine the effect of administration of human growth hormone-releasing factor (1-29)NH2 (GRF) and(or) thyrotropin-releasing factor (TRF). Calves received twice-daily s.c. injections of .9% NaCl (control), GRF (5 micrograms/kg BW), TRF (1 micrograms/kg BW) or GRF (5 micrograms/kg BW) plus TRF (1 micrograms/kg GTRF). Average daily gain and days on feed were not affected by treatments, but TRF treatment increased (P less than .05) total intake of dry matter (DM) and feed conversion ratio: 3.00, 3.02, 3.08, and 3.22 kg DM/kg weight gain for control, GRF, TRF, and GTRF, respectively. During two 7-d periods, after 66 and 75 d of treatment, feces and urine were collected from 40 calves (5 per treatment per period). Treatment with GRF increased (P less than .05) digestibility of DM, nitrogen (N), and energy and tended (P less than .20) to increase N retention. At slaughter, withers height was increased (P = .05) by GRF and carcass length was increased (P less than .05) by TRF. Pituitary and liver weights were increased (P less than .05) by TRF. The combination of GRF and TRF slightly increased (P less than .10) protein content and decreased (P less than .05) fat content of the 9-10-11th rib section. After d 1, GRF treatment chronically increased (P less than .05) insulin concentrations and also increased (P less than .10) IGF-I concentrations on d 29 and 57. In summary, chronic treatment with GRF and(or) TRF did not improve growth or efficiency, although GRF increased digestibility of DM, N, and energy and the GRF plus TRF combination resulted in slightly leaner carcasses.