Introduction and elimination of Bovine Viral Diarrhoea Virus in a commercial beef herd: a case study

Routine Bovine Viral Diarrhoea Virus (BVDV) monitoring of a commercial beef herd in southern New South Wales over a 10-year period provided an opportunity to assess the impact of the introduction of BVDV on that herd. BVDV antibody testing provided strong evidence that the herd was initially free of BVDV (2009–2011). Testing from 2012 suggested BVDV had been introduced into the herd and this was confirmed in 2015 with the identification of persistently infected (PI) animals. Having become established in the herd, the owners then set out to eliminate BVDV from the herd. Antigen testing aimed at identifying PI animals revealed BVDV was already absent from the herd. Subsequent antibody testing confirmed that the herd was now free from BVDV. Despite the incursion of BVDV in this herd, there was little measurable impact on reproductive performance (pregnancy rates), although suspected increased calf losses from birth to calf marking were reported. This is the first time such self-clearance has been documented as part of a longitudinal study under Australian conditions.     

Changes in fatty acids composition during seed growth and physicochemical characteristics of oil extracted from four safflower cultivars

Fatty acid contents at different stages ofmaturity and physicochemical characteristics of oilextracted from mature seeds of four safflowercultivars (S208, S400, S541, and S303) were studied. Results indicated that for all cultivars bothsaturated and unsaturated fatty acid contentsfluctuated with seed growth and development. Palmiticacid content decreased up to day 20 after which itstarted to increase for the S400, S541, and S303cultivars, while for S208 it progressively decreased.Stearic acid fluctuated with seed growth anddevelopment. Oleic acid showed slight changes withseed growth and development, while linoleic aciddecreased with seed growth and development for theS400, S541, and S303 cultivars while for S208 afterday 30, it started to increase significantly. For allcultivars, glyceride contents varied among thecultivars with maximum values of 97.70, 2.80 and0.20 for tri-, di- and monoglycerides, respectively. Physicochemical investigation of mature seed oilsshowed that the color, density, refractive index, free fatty acids, peroxide value, saponificationvalue and unsaponifiable matter were similar for allcultivars while viscosity, iodine value, and acetoneinsoluble matter varied among the cultivars.     

Recommendations of the International Roundtable Workshop on Bovine Spongiform Encephalopathy.

Recommendations of the working party were summarized as follows: Determine the status in all countries of their national cattle herds with respect to BSE. Attempt to develop a test to recognize BSE-infected animals before they become clinically ill. Establish procedures to prevent spread of BSE agent into the cattle populations, especially by eliminating feeds containing rendered ruminant proteins. Review the rendering processes, identify the sources and destinations of rendered products, and suggest appropriate changes if needed. Especially needed are standardized rendering procedures in regard to use of organic solvents, temperature, and duration of heat treatment. Review import and export regulations to reduce the risk of spreading BSE and to maximize opportunities for safe trading in cattle and cattle products. The scrapie-free certification program of the USDA was supported, and similar programs might be considered by other countries. If BSE/scrapie is diagnosed in a given country, determine baseline incidence of CJD in those countries and consider contributing to an international registry. The WHO should address the problems of BSE, formulate policy, participate in and coordinate research, and provide training opportunities for veterinary and human health care workers from eastern European countries and developing nations. Government and private agencies should consider increasing support for research on transmissibility and pathogenesis of CJD, BSE, CWD, scrapie, and transmissible mink encephalopathy. Prepare and publish a critical neuropathologic review of all spongiform encephalopathies, naturally and experimentally transmitted, defining the characteristics of each disease in the various species known to be susceptible. Consider producing guidelines for the biological and pharmaceutical industries with regard to sourcing, collecting, and processing bovine and ovine materials.(ABSTRACT TRUNCATED AT 250 WORDS)     

Growth traits of four maternal lines of rabbits founded on different criteria: comparisons at foundation and at last periods after selection

The objective was to compare growth traits in four maternal lines of rabbits (A, V, H and LP), with the aim of understanding the consequence of the different foundation and selection processes on the growth performance of the lines. The lines are currently in the 43th, 38th, 22th and 8th generations, respectively. Two comparisons were performed. One compared the values of the lines at their foundation, using the complete data set, the full pedigree and a two‐trait analysis, including data on the selection criteria, litter size. The other comparisons were done during the last period when all the lines were housed together with the same feeding and management. The numbers of records were 323 208 for weaning weight, and 300 553 for slaughter weight and average daily Gain (from 46 708 l). The pedigree file included 346 638 animals. The second analysis used only the data corresponding to each period, and the analysis was conducted using a one‐trait model. The model was the same as that defined for the comparisons at the foundation, but the additive effects were excluded. The H and LP lines showed highest values for all the traits compared. In the last periods, a good agreement was observed between the estimated differences, computed with the complete model and data set, or computed with an incomplete model and only data from the comparison period. At last periods, the differences were smaller than at foundation. The importance of the correlated response in growth after selection for litter size at weaning or the importance of a non‐programmed intramating selection for the growth traits can explain the changes since foundation.     

Adverse immune reactions and the pathogenesis of Ostertagia ostertagi infections in calves

The possible development of type-1 hypersensitivity reactions in the abomasal mucosa caused by soluble L3 products of Ostertagia ostertagi was studied in 4-month-old calves sensitized by repeated exposure to L3 over a 50-day period followed by anthelmintic treatment. Four groups each of 4 calves were used. Group 1 served as nonsensitized controls and group 2 as sensitized controls, group 3 was challenge exposed at 2-week intervals beginning at week 10 with a soluble L3 product (OAG), and group 4 was challenge exposed at 2-week intervals with an oral dose of L3, followed by anthelmintic treatment 3 days later. All calves infected with L3 became sensitized, as indicated by a positive reaction to an intradermal skin test. However, a passive cutaneous anaphylaxis was only partly effective in indicating the presence of homocytotropic antibody in the infected calves. Sensitized calves had significantly (P less than 0.05) higher eosinophil counts and plasma pepsinogen values for the entire 14 weeks than uninfected controls. Globule leukocyte and mast cell counts from the abomasal mucosa were also significantly (P less than 0.05) higher. Studies for possible immunomodulation revealed that lymphocyte counts decreased between every 2-week challenge-exposure period for groups-3 and -4 calves. A transient depression of blood lymphocyte (BL) responses to phytohemagglutinin (PHA), a T-cell mitogen, was observed over the first 8 weeks in the infected calves. Increases in BL responses to OAG were also observed. Differences were not observed in BL responses to pokeweed mitogen, a T- and B-cell mitogen. Blood lymphocyte responses to PHA in group-3 calves were low following the initial challenge exposure with OAG.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effectiveness of a slow-release, morantel tartrate anthelmintic bolus for controlling parasitic gastroenteritis in replacement dairy heifers

Two experiments were done to evaluate the effectiveness of a slow-release, morantel tartrate, anthelmintic bolus for controlling parasitic gastroenteritis in replacement dairy heifers. In experiment 1, good control of nematode contamination of pasture was indicated by lower worm burdens in tracer calves that grazed with 15 heifers treated orally with a single bolus and by significantly decreased numbers of nematode eggs in the feces of the 15 treated heifers, as compared with numbers of eggs in the feces of 15 nontreated control calves. Significant differences in weight gain were not seen between treated and nontreated heifers, probably due to low amounts of larval exposure, the small number of heifers evaluated, and parasitic resistance in the heifers, which may have developed as a result of prestudy exposure to contaminated pasture. In experiment 2, done 1 year after the 1st experiment, using the same pastures that were used in experiment 1, young heifers were used. Many of the heifers were parasite naive at the beginning of the experiment (ie, nematode eggs were not found before the experiment). Treatment with the bolus was effective in controlling parasitic gastroenteritis in the heifers and in controlling nematode contamination of pasture. Compared with nontreated heifers, treated heifers had significantly higher cumulative weight gains, a significant decrease in plasma pepsinogen concentrations, and a significant decrease in worm egg excretion. The number of worms acquired by tracer calves that were grazed with treated heifers was significantly less than for tracer calves that were grazed with nontreated heifers.     

Reproductive traits, lactation and foal growth in mares fed altrenogest

Lactating mares were assigned as controls or fed altrenogest (.044 mg.kg body wt-1.d-1) for 15 d after foaling. Mares (n = 6) fed altrenogest were inseminated during the first estrus after treatment and mares (n = 6) in the control group were inseminated during the second postpartum estrus. Ovulation during the estrus in which mares were inseminated occurred 26 +/- 1 d postpartum for treated mares and 36 +/- 1 d postpartum for control mares. The percentage of mares conceiving was not different for control (67%) and alternogest-treated (100%) mares. No differences were observed in tone and size of the uterus or size of the ovulatory follicle between treated and control groups. Uterine cultures and biopsies collected on d 7 and 15 postpartum were similar between treatment and control groups in bacterial populations or endometrial epithelial cell height. Blood was collected on d 7, 11, 15, 19 and 23 postpartum, and concentrations of estradiol-17 beta in serum were determined by radioimmunoassay. Mean concentrations of estradiol-17 beta across days were 10 +/- .8 and 12 +/- .6 pg/ml for control and treated mares, respectively. Concentrations of serum estradiol-17 beta were higher (P less than .05) in treated mares on d 23 postpartum. Daily milk yields, determined by the weigh-suckle-weigh method, and milk composition were similar between treatment groups on each collection day. Altrenogest can be used to predictably delay estrus in the postpartum mare without altering fertility, yield and composition of milk, or foal growth.     

The recreational and commercial importance of feral swine in Florida: Relevance to the possible introduction of African swine fever into the U.S.A.

Florida has the largest population of feral swine in the U.S.A. Feral swine have recreational and economic importance to hunters, trappers, taxidermists, and also to dealers who sell feral swine to hunting clubs. Hunters spent over 522 00 man-days hunting feral swine during the 1980–1981 hunting year. They killed nearly 103 000 hogs which they valued at over $58 each, for a total value of nearly $6 million. Trappers caught 25 000 head valued at about $ 700 000, and landowners collected about $1.2 million in hunting lease fees. Taxidermists received about $389 000 in gross income from mounting feral swine. Sales of feral swine to hunting clubs amounted to about $81 000.

Sales of feral swine through commercial livestock auctions were limited to 1620 head valued at only $16 800 in 1980. Thus, feral swine are important to Florida from a recreational standpoint, but not from the perspective of commercial agriculture.

If African swine fever were to enter Florida, there are many socio-economic factors associated with feral swine that must be carefully evaluated for eradication to be successful.     

Studies of the immunomodulatory effects of low-level infection with Ostertagia ostertagi in calves

Possible immunomodulation by low-level infection with Ostertagia ostertagi was studied in 4-month-old calves. Six groups of 4 calves each were subjected to the following regimens: group 1--nonparasitized controls; group 2--nonparasitized, but challenge exposed at day 64 with Brucella abortus strain 19 vaccine (BA) and at day 78 with IV administration of a soluble third-stage larval (L3) antigen preparation of O ostertagi (OAG); group 3--nonparasitized, but challenge exposed at day 78 with 75 x 10(3) L3 of O ostertagi; group 4--continuously parasitized by weekly dosing with 30 x 10(3) L3 of O ostertagi; group 5--continuously parasitized by weekly dosing with 30 x 10(3) L3 of O ostertagi, then challenge exposed on day 64 with BA and on day 78 with IV inoculation of OAG; and group 6--continuously parasitized by weekly dosing with 30 x 10(3) L3 of O ostertagi, then challenge exposed on day 78 with 75 x 10(3) L3 of O ostertagi. Over the initial 10 weeks of the study, nonparasitized calves, (groups 1, 2, and 3) had higher body weight, blood lymphocyte (BL) response to phytohemagglutinin (PHA), and significantly (P less than 0.05) higher feed consumption and lymphocyte numbers, whereas parasitized calves (groups 4, 5, and 6) had higher BL responses to pokeweed mitogen (PWM) and significantly (P less than 0.05) higher neutrophil and eosinophil numbers, plasma pepsinogen (PP) values, and BL response to OAG.(ABSTRACT TRUNCATED AT 250 WORDS)