畜禽养殖场环境微生物致病性和耐药性调查研究

为了解掌握养殖场中环境微生物对养殖业和公共卫生造成的影响,初步对我国养殖场环境微生物进行了研究。对吉林、湖北等省份的部分养猪场和养鸡场环境采样,并进行大肠杆菌和沙门氏菌分离鉴定,同时对从鸡舍和猪舍内分离大肠杆菌和沙门氏菌进行动物致病性实验及对13种抗生素的耐药性实验。实验结果表明,所有实验的沙门氏菌和90.7%的大肠杆菌菌株对小白鼠有致病性;所有分离菌株对磺胺类药物的耐药性非常严重,其次是对四环素,对其他药物也有不同程度的耐药性。     

Progestogen-related gross and microscopic changes in female Beagles.

Long-term studies of megestrol acetate and chlormadinone acetate in 100 female dogs are in progress. Doses of zero, one, 10 and 25 times the expected human dose of megestrol acetate and 25 times the expected human dose of chlormadinone acetate (on a milligram per kilogram body weight basis) are being given daily. During the first 4 years, eight dogs from each of the five groups were killed. The principal gross findings included enlarged uteri with mucoid material in the lumina, mammary development in dogs given middle and high doses of megestrol acetate and chlormadinone acetate, and thickened gallbladder walls in dogs given high doses of each. Histologic evaluation showed inhibition of ovulation for progestogen-treated dogs and suppression of ovarian follicular development with the high doses. Cystic endometrial hyperplasia was slight in the low-dose dogs and moderate to severe in most of the high-dose dogs; a few also had ulcerative endometritis and pyometra. The mammary glands of dogs given the middle and high doses produced lobules, acini, and secretion exceeding natural metestrus. Slight to marked cystic mucinous hyperplasia occurred in the gallbladders of most dogs given the high doses. Tow high-dose megestrol dogs had clinical signs and microscopic pancreatic, renal, and ocular changes indicative of diabetes mellitus.     

Effect of supplementing graded concentrations of non-phytate phosphorus on performance,egg quality and bone mineral variables in White Leghorn layers

1. An experiment was conducted to determine optimal non-phytate phosphorus (NPP) concentrations for White Leghorn (WL) layers (22–72 weeks) fed diet containing 38 g Ca/kg.

2. Eight diets with graded concentrations (1.5–3.25 g/kg in increments of 0.25 g) of NPP were prepared. Each diet was fed to eight pen replicates containing 88 birds in each. Performance data was evaluated in three different phases (phase I-22–37 weeks, phase II-38–53 weeks and phase III-54–72 weeks). Optimum levels of NPP were determined by fitting a quadratic polynomial (QP) regression model.

3. Egg production (EP) was not affected (P = 0.059) by the concentration of NPP and interaction between NPP and diet phase was non-significant, indicating that the lowest concentration (1.5 g/kg diet) of NPP used in the study was adequate across the three phases. However, EP was influenced by phase (P < 0.001).

4. Optimum concentration of NPP for feed intake (FI) was estimated to be 1.5, 1.71 and 2.40 g/kg diet during phases I, II and III, respectively. FI per egg mass (EM) or feed efficiency (FE) responded quadratically with NPP and also differed significantly between phases. Optimum concentration of NPP for FE during phases I, II and III was 1.5, 2.56 and 2.32 g/kg diet, respectively.

5. Egg weight (EW), EM, shell weight and thickness were not affected by NPP concentration although all of these variables (except shell weight) were influenced by phases.

6. Breaking strength of tibia and Ca contents in tibia ash were not affected by the concentration of NPP, but bone ash and P contents in tibia ash were influenced (P < 0.001) by NPP. Predicted optimal concentrations of NPP for responses for tibia ash at 44 or 72 weeks, tibia ash P at 44 weeks and tibia ash P at 72 weeks were 1.55, 2.63 and 1.5 g/kg diet, respectively.

7. Based on the results, it was concluded that WL layers required 1.5 g, 2.63 g and 2.4 g, respectively/kg diet during phase I, II and III with the calculated daily intake of 137.3, 278.3 and 262 mg NPP/b/d.     

Digesta kinetics, energy intake, grazing behavior, and body temperature of grazing beef cattle differing in adaptation to heat

The objective of this study was to determine whether digesta kinetics, energy intake (EI, kcal ME intake x kg(-.75) x d(-1)), grazing behavior, or body temperature differed by breed, lactational state, or season of the year among cattle presumed to vary in adaptability to the subtropics. Two-year-old lactating and nonlactating Brahman x Angus (BA; n = 5, n = 5), Tuli x Angus (TA; n = 5, n = 4), and Angus (A; n = 4, n = 4) cows were used. During both early (ES) and late summer (LS), lactating cattle vs nonlactating cattle had greater gastrointestinal tract load (CM2) and EI (P < .01), although passage rate did not differ (P > .48). During LS, lactating cattle had decreased early morning rectal temperatures (P < .05) and spent more time grazing during the day compared with nonlactating cattle (P < .001). Among breeds, A had the largest CM2 (P < .01 compared with BA and P = .068 compared with TA) and accumulated the greatest heat during the day (P < .05). Due to greater daytime shading (P < .01) and less daytime grazing (P < .05), A had lower (P < .05) early morning and comparable (P > .26) late afternoon rectal temperatures compared with BA and TA. With data pooled over both grazing trials, BA cattle had the smallest CM2 (P < .01), and in ES they spent the least amount of time in the shade (P < .001). The TA spent more time in the shade than did BA (P < .001) during ES and less during LS (P < .001) and had similar (P > .28) early morning rectal temperatures compared with BA during ES and LS. During LS, TA spent more time in the sun and less time in the shade than did either A or BA (P < .001). During ES, EI did not differ among breeds (P > .50). During LS, EI for lactating A was greater than for BA and TA (P < .05), and EI for nonlactating BA was less than for A and TA (P < .05). Bite rate per minute for lactating cattle during ES was reduced (P < .03) by increased body condition score. Tuli x Angus cattle appear to be comparable to BA with respect to heat adaptation. It appears that EI demands are greater in a hot environment.     

Nutritional evaluation of sunflower seed and products derived from them. Effect of oil extraction

1. Apparent MEn and oil digestibility of hulled sunflower seed (SFS) and the products derived from the oil extraction process: press extracted SFS (PESFS), sunflower seed meal (SFSM), and press and solvent oils (PO and SO) were determined with 198 cockerels. Recombined products (mix of meal and oil) were also evaluated to study the effect of the 2 consecutive oil extraction steps. Each foodstuff was included in a basal diet, according to the proportions resulting from processing, at 100, 200, and 300 g SFS/kg. 2. Dietary energy value and digestible fat content were linearly related to rate of inclusion of test ingredients. Extrapolation values for AMEn (MJ/kg DM) were: SFS, 16.20; PESFS, 9.46; SFSM, 7.62. A decreasing quadratic trend was also found in the AMEn of PESFS, with interpolation values ranging from 11.77 to 9.33 MJ/kg DM between 70 and 210 g/kg DM of inclusion. No differences were observed between PO and SO. The AMEn of of sunflower oil, calculated from its digestibility, was 33.70 MJ/kg DM. 3. The oil extraction process affected the nutritional value of sunflower products. Recombined materials showed greater values than original foodstuffs: R-SFS, 17.47; R-PESFS, 11.49 MJ/kg DM. The increase in oil digestibility (from 0.814 to 0.862 g/kg DM in SFS; from 0.778 to 0.892 in PESFS) accounted for most of the increase observed in AMEn values. 4. As the form in which oil is incorporated in diets (released or within SFS or PESFS) affects the utilisation of sunflower products, their nutritional value is less than maximal and should not be calculated from their ingredients. Solvent oil seems to be the less available fraction of sunflower oil within SFS as the effect of the 2nd extraction proved to be greater than that of the previous press extraction.     

Synovial fluid analysis in cattle: a review of 130 cases

OBJECTIVE: To compare synovial fluid characteristics of cattle with infectious and noninfectious arthritis. STUDY DESIGN: Retrospective cohort study. ANIMAL OR SAMPLE POPULATION: 130 cattle. METHODS: Synovial fluid was analyzed for total nucleated cell count (NCC), absolute number and percentages of polymorphonuclear (PMN) and mononuclear cells, total protein (TP) concentration, and specific gravity. Cattle were categorized as having infectious or noninfectious arthritis based on physical and lameness examinations, joint radiographs, and microbial culture results. Kruskal-Wallis 1-way analysis of variance was used to compare synovial fluid analysis data from different categories. Selection of cut-off values for the calculation of likelihood ratios, sensitivity, specificity, and positive and negative predictive values was based on examination of the distribution of the data using histograms. RESULTS: Cattle with infectious arthritis had significantly higher numbers of total NNC, PMN cells, TP concentration, and specific gravity (P = .0001) and a significantly higher percentage of PMN cells compared with cattle with noninfectious arthritis (P = .0001). The percentage of mononuclear cells was significantly higher in cattle with noninfectious arthritis (P = .0001). CONCLUSIONS: Synovial fluid analysis is useful for differentiation of infectious and noninfectious causes of joint disease in cattle. CLINICAL RELEVANCE: Cattle with a synovial fluid total NCC > 25,000 cells/microL, a PMN cell count > 20,000 cells/microL or more than 80% PMN cells, and TP > 4.5 g/dL should be considered to have infectious arthritis.     

Lesions and effects of location for administration of clostridial bacterin-toxoid vaccines on growth performance and eating and drinking behaviors in newly arrived calves at a feedlot

OBJECTIVES: To determine the effect of location for administration of clostridial vaccines on behavior, growth performance, and health of calves at a feedlot, the relative risk of calves developing an injection-site reaction or being misdiagnosed as having bovine respiratory disease complex (BRDC), and the percentage of subcutaneous injection-site reactions that were detectable on carcasses after the hides were removed. ANIMAL: 170 newly arrived calves at a feedlot. PROCEDURE: Eating and drinking behaviors of calves during the initial 57 days after arrival were observed at a commercial feedlot, using an electronic monitoring system. Calves were assigned randomly to receive a clostridial vaccine (base of ear or neck). Data on reactions at the injection site were collected. RESULTS: Mean daily gain (MDG) for the initial 57 days did not differ significantly between treatments. Risk of being misdiagnosed as having BRDC was not associated with location for administration of vaccine. Calves vaccinated in the base of the ear were at higher risk of having an injection-site reaction at day 57 or at slaughter. Eighty-nine percent (95% confidence interval, 52 to 100%) of injection-site reactions in the neck could not be located on the carcasses after hides were removed. Calves vaccinated in the neck drank significantly fewer times per day during the first 57 days than calves vaccinated in the base of the ear. CONCLUSIONS AND CLINICAL RELEVANCE: Location for administration of a clostridial vaccine did not significantly affect health, growth performance, or eating behavior. Most subcutaneous injection-site reactions were not detectable after the hide was removed.