A Study on the Effects of Insect Pests and Diseases on Intensively Managed Plantations

Basedon the results of monitoring the environment of China National Afforestation Project (NAP) and the investigation on insect pests and diseases in 1.2 million ha of plantations, the author elaborates the areas, species and causes of insect pests and diseases occurring in the project's areas and provides fundamental theory for guiding environmental protection and plantation establishment in a sound way. Since the project's activities strictly follovved the guideline of environmental protection in past five years, little losses were caused by some commonly insect pests and diseases.     

Anthropogenic Input of Selected Heavy Metals (Cu, Cr, Pb, Zn and Cd) in the Aquatic Sediments of Hochiminh City, Vietnam

The aquatic system of Hochiminh City comprises two main rivers: the Sai Gon and Nha Be rivers. Five canals discharge into these two rivers: NhieuLoc-ThiNghe, TauHu-BenNghe, TanHoa-LoGom, ThamLuong-BenCat and Doi-Te. The rivers and these canals collect effluent water from domestic and industrial sources. Most of these flows are not treated or at most are only primarily treated. A total of 33 sediment cores were taken from these rivers and canals. Chemical composition of these aquatic sediments has very high concentrations of several “urban” metals such as Cd, Cr, Cu and Zn. Most of the samples have exceeded the US EPA’s toxicity reference values for Cu, Zn and Cr (82, 82 and 70%, respectively). The highest concentrations of these metals appear to be associated with the uncontrolled and untreated industrial runoff to the discharge canals. These concentrations in fluvial sediment are relatively low, which indicates the dilution process of the contaminants. This finding indicates that the anthropogenic inputs play an important role in the elevation of heavy metals in the aquatic system and organic matter seems to exert a strong geochemical control on the amount of heavy metals. The Pearson correlation coefficients calculated for Cd, Cr, Cu and Zn, are 0.89; 0.72; 0.93 and 0.87, respectively.     

Fusobacterium necrophorum and Bacteroides melaninogenicus as etiologic agents of foot rot in cattle.

Fusobacterium necrophorum (Sphaerophorus necrophorus) and Bacteroides melaninogenicus were the predominant bacteria isolated from biopsy specimens of lesions in cattle affected with foot rot. Mixed inoculums of the 2 bacteria, applied to the scarified interdigital skin or inoculated intradermally into the interdigital skin of test cattle, induced typical lesions of foot rot. Both bacteria were reisolated in large numbers from the induced lesions.     

A live Pasteurella haemolytica vaccine efficacy trial

A live Pasteurella haemolytica serotype 1 vaccine was used in an efficacy trial conducted on 100 lightweight feeder calves purchased from a Florida ranch. Forty-one calves were inoculated with the vaccine intradermally in the neck. Fifty-nine calves served as nonvaccinated controls. Fourteen days later, the calves were shipped to an order buyer in eastern Tennessee, where the calves were mixed with 60 local calves in a community sale barn for 72 hours. After 3 additional days, the calves were shipped to a research feedlot in Bushland, Tex. They remained in the feedlot for 56 days, and the test was concluded 76 days after vaccination. The P haemolytica vaccine had no significant effect on performance, morbidity, or mortality. There was no significant difference between the vaccinated and nonvaccinated calves in the number of times Pasteurella was isolated. The calves became seropositive to bovine viral diarrhea virus, respiratory syncytial virus, and infectious bovine rhinotracheitis (IBR) virus during the 76-day experiment. All calves initially were seropositive to parainfluenza-3 virus. A virulent outbreak of IBR occurred 30 days after the calves arrived at the feedlot. Before the onset of IBR, the isolation of P haemolytica serotype 1 from nasal turbinates was rare (2 of 500 nasal swabs). After the IBR outbreak, P haemolytica serotype 1 was isolated from 40 of 92 calves.     

Effect of transport stress on respiratory disease, serum antioxidant status, and serum concentrations of lipid peroxidation biomarkers in beef cattle

OBJECTIVE: To determine the effect of transportation stress on serum concentrations of oxidative stress biomarkers of calves. ANIMALS: 105 crossbred beef steer calves (mean [+/-SD] body weight, 207 +/- 21.2 kg). PROCEDURE: Calves were assembled at 1 location in Tennessee, and pretransit (day -3) blood samples were collected. Calves were allotted randomly by body weight into 2 groups. Calves were transported 1,930 miles to a feedlot in Texas, and 1 group received tilmicosin phosphate (33 microg/kg, s.c.) upon arrival. Calves were weighed and blood samples collected on the day of arrival (day 1) and on days 15, 22, and 28. Calves were scored daily for signs of bovine respiratory disease (BRD). Serum total antioxidant capacity (TACA) and serum malondialdehyde (MDA) concentrations were determined. RESULTS: Transportation stress significantly decreased mean serum TACA concentrations (from 147 +/- 31.2 U/mL to 133 +/- 20.1 U/mL) and significantly increased serum MDA concentrations (from 10.9 +/- 18.3 microg/mL to 30.2 +/- 50.5 microg/mL). Calves that died had a 43% increase in serum MDA concentration on day 1, compared with calves that lived (42.2 +/- 67.0 microg/mL vs 29.4 +/- 49.4 microg/mL, respectively). Calves that had > or =3 episodes of BRD had 2-fold higher serum MDA concentrations on day 1 than healthy calves. Tilmicosin-treated calves had a 20.8% significantly greater average daily gain and significantly greater serum TACA concentration than nontreated calves on day 28. CONCLUSIONS AND CLINICAL RELEVANCE: Transportation stress increases serum concentrations of oxidative stress biomarkers that are related to episodes of BRD and mortality in calves.     

Bovine viral diarrhea virus (BVDV) 1b: predominant BVDV subtype in calves with respiratory disease

The prevalence of bovine viral diarrhea virus (BVDV) infections was determined in 2 groups of stocker calves with acute respiratory disease. Both studies used calves assembled after purchase from auction markets by an order buyer and transported to feedyards, where they were held for approximately 30 d. In 1 study, the calves were mixed with fresh ranch calves from a single ranch. During the studies, at day 0 and at weekly intervals, blood was collected for viral antibody testing and virus isolation from peripheral blood leukocytes (PBLs), and nasal swabs were taken for virus isolation. Samples from sick calves were also collected. Serum was tested for antibodies to bovine herpesvirus-1 (BHV-1), BVDV1a, 1b, and 2, parainfluenza 3 virus (PI3V), and bovine respiratory syncytial virus (BRSV). The lungs from the calves that died during the studies were examined histopathologically, and viral and bacterial isolation was performed on lung homogenates. BVDV was isolated from calves in both studies; the predominant biotype was noncytopathic (NCP). Differential polymerase chain reaction (PCR) and nucleic acid sequencing showed the predominant subtype to be BVDV1b in both studies. In 1999, NCP BVDV1b was detected in numerous samples over time from 1 persistently infected calf; the calf did not seroconvert to BVDV1a or BVDV2. In both studies, BVDV was isolated from the serum, PBLs, and nasal swabs of the calves, and in the 1999 study, it was isolated from lung tissue at necropsy. BVDV was demonstrated serologically and by virus isolation to be a contributing factor in respiratory disease. It was isolated more frequently from sick calves than healthy calves, by both pen and total number of calves. BVDV1a and BVDV2 seroconversions were related to sickness in selected pens and total number of calves. In the 1999 study, BVDV-infected calves were treated longer than noninfected calves (5.643 vs 4.639 d; P = 0.0902). There was a limited number of BVDV1a isolates and, with BVDV1b used in the virus neutralization test for antibodies in seroconverting calves' serum, BVDV1b titers were higher than BVDV1a titers. This study indicates that BVDV1 strains are involved in acute respiratory disease of calves with pneumonic Mannheimia haemolytica and Pasteurella multocida disease. The BVDV2 antibodies may be due to cross-reactions, as typing of the BVDV strains revealed BVDV1b or 1a but not BVDV2. The BVDV1b subtype has considerable implications, as, with 1 exception, all vaccines licensed in the United States contain BVDV1a, a strain with different antigenic properties. BVDV1b potentially could infect BVDV1a-vaccinated calves.