Serum chemical profile of feeder pigs, as influenced by market stress and feeding regimen

Two hundred eighty-eight crossbred feeder pigs were used in 2 trials to determine the effects of feed and/or water deprivation at an auction market, and the effects of restricting the intake of the receiving diet on their serum chemical profile. The study also was designed to assess the value of the serum chemical profile as a diagnostic data base for stress disorders in feeder pigs. Performance data indicated that feeder pigs provided water only at the auction facilities lost significantly more weight than did those provided feed and water. Feeder pigs deprived of both feed and water were not significantly different in body weight from either group. Several serum chemical values (creatinine, triglycerides, cholesterol, blood urea nitrogen, and lactate dehydrogenase) were significantly influenced by feed deprivation, but not by feed and water deprivation. However, only the serum creatinine values were significantly different after the 24-hour posttransport period. There were no significant differences in pig weight or serum chemical values 84 days after pigs had arrived at the finishing unit. The serum chemical profile, widely used in human medicine, appears not to provide a reliable marker for identification of short-term nutritional deprivation, nor for transport stress in feeder pigs.     

Pulmonary lesions induced by Pasteurella haemolytica in neutrophil sufficient and neutrophil deficient calves.

The role of neutrophils in the development of peracute lung lesions of bovine pneumonic pasteurellosis was investigated. Eight calves were divided into two groups of four calves each. Group I was treated with intravenous phosphate-buffered saline and served as the neutrophil sufficient calves. Group II was treated with intravenous hydroxyurea which produced a state of neutropenia. When peripheral blood neutrophil numbers dropped below 300 cells/microL in group II, all calves were challenged with an intrabronchial bolus of Pasteurella haemolytica in the log phase of growth. An acute inflammatory process occurred in both groups of calves indicated by a rise in body temperature. While pulmonary lesions occurred in both groups by six hours postinoculation, they varied in pathological characteristics. Pulmonary lesions in the neutrophil sufficient calves consisted of fibrinopurulent alveolitis-bronchiolitis with associated alveolar septal necrosis, interlobular edema, and intravascular thrombi. The neutrophil deficient calves had extensive intra-alveolar edema, interlobular edema, intraalveolar hemorrhage, atelectasis, and focal areas of alveolar septal necrosis. These results show that P. haemolytica can induce severe pulmonary tissue damage through both neutrophil dependent and neutrophil independent mechanisms.     

Factors affecting the infectivity of lymphocytes from cattle with bovine leukosis virus.

Peripheral blood mononuclear cells were obtained from 13 bovine leukosis virus infected cattle and inoculated subcutaneously into 29 recipient adult steers to determine (a) the number of mononuclear cells (equivalent amount of blood) necessary to cause infection and (b) factors influencing infectivity of mononuclear cells from bovine leukosis virus-infected animals. A total of 55 inoculations were made. Inoculation of 1 X 10(4), 2 X 10(4) and 5 X 10(4) mononuclear cells caused seroconversion in 12%, 57% and 62% of steers, respectively. No infections occurred with 1 X 10(3) or 2 X 10(3) mononuclear cells. Cattle infected for longer than 24 months and those animals greater than three years of age were more likely to cause infection with 1 to 5 X 10(4) mononuclear cells than were cattle infected for less than 24 months or animals less than three years of age. Lymphocytes from cattle with persistent lymphocytosis caused more infections when 1 X 10(4) or 2 X 10(4) mononuclear cells were inoculated, than did lymphocytes from nonpersistent lymphocytosis cattle; however, both groups were equally infectious when 5 X 10(4) mononuclear cells were inoculated. No differences were found in infectivity of experimentally vs naturally exposed animals.     

The canine lymphocyte: effect of streptolysin O on the proliferative response of canine lymphocytes

The effects of Streptolysin O (SLO) on canine peripheral blood lymphocytes were studied using the lymphocyte blastogenesis test (LBT). Canine lymphocytes stimulated with SLO produced a response that was similar to the response obtained with the commonly used phytomitogens: phytohemagglutinin (PHA), concanavalin A (CON A) and pokeweed mitogen (PWM). When SLO was added to any of the phytomitogens and incubated with canine lymphocytes, an additive or stimulatory response was obtained. However, mixing the phytomitogens in any combination did not produce a similar additive or stimulatory response. The results were interpreted to mean that in the canine system, the binding of SLO to lymphocytes does not sterically interfere with receptors for PHA, CON A, or PWM. Additionally, SLO may stimulate a population of lymphocytes that is distinct from that stimulated by the phytomitogens. Moreover, it would appear that the phytomitogens probably stimulate the same or an overlapping population of lymphocytes. Experiments using enriched lymphoid cell populations were used to characterize the lymphocytes stimulated by phytomitogens and SLO. Lipopolysaccharides from two different bacteria were unable to cause a significant lymphoproliferative response.     

Isolation and characterization of porcine natural killer (NK) cells

The morphologic and biological properties of porcine cells mediating natural killer (NK) activity were determined. In a previous study, we demonstrated that lymphocytes from the peripheral blood of pigs greater than 1 week of age possessed NK activity to K562 tumor cells and that lymphocytes from the blood and spleen of pigs greater than 1 day of age were able to mediate natural cytotoxicity against parainfluenza-3 (PI3) virus-infected Vero cells (Yang and Schultz, 1986a). Discontinuous density gradients were used to enrich NK cells. NK cytotoxicity was mainly present in high-density Percoll fractions (50 to 55% and 55 to 60%); little or no NK activity was present in lower density fractions. The NK cell enriched lymphocytes responded to the mitogens PHA, ConA and PWM. NK cells were sensitive to the suppressive effect of corticosteroid, but Protein A did not affect NK activity. The amount of cytotoxicity directly corresponded to the degree of binding that occurred between the NK enriched lymphocyte population and the target cells. Cytochemical and morphological studies demonstrated that these bond cells which are believed to be responsible for the NK activities, were mainly small to medium lymphocytes lacking azurophilic cytoplasmic granules. These findings were confirmed by ultrastructural studies of effector and "target-binding" cells. The results of the present study suggested that the cells mediating NK activity in pigs have the morphological and density characteristics of small and medium sized lymphocytes; findings that differ from those described for NK cells in human and other animal species.     

Determination of the intramammary dose of benzylpenicillin required to maintain an adequate concentration in the milk to inhibit Gram‐positive bacteria in the clinically normal udder for 24 hr

The aim of this study was to determine the intramammary dose of benzylpenicillin required to maintain a concentration in the milk above the MIC for the Gram‐positive bacteria that cause mastitis. The product used in this study was a commercially available procaine benzylpenicillin in an oily suspension with micronized particles. Three dose levels were used: 200,000, 300,000, and 600,000 IU. Concentrations of benzylpenicillin in cow milk and plasma were determined after a single intramammary dose was administered into one quarter of each of the five cows in each treatment group. Samples were analyzed using an HPLC‐MS/MS method, which was validated during the study. Concentrations in the milk were well above the MIC for the target pathogens for all doses tested. There was a linear dose‐dependent increase in the mean AUCs of benzylpenicillin concentrations in plasma and milk. At the first milking, 12 hr after dosing, there was a significant difference between the mean milk benzylpenicillin concentrations in cows treated with a dose of 600,000 IU, and those treated with 200,000 or 300,000 IU. Although this study shows a linear relationship between the dose of procaine benzylpenicillin administered and the concentration in the milk in the healthy udder, it would be useful to conduct studies on cows with mastitis to define the optimum dose and duration of intramammary treatment with benzylpenicillin.