Lelystad virus, the cause of porcine epidemic abortion and respiratory syndrome: a review of mystery swine disease research at Lelystad.

This paper reviews the laboratory investigations that led us to isolate the Lelystad virus and demonstrate that this virus causes mystery swine disease. We describe: 1) isolating the virus from the disease; 2) characterizing the virus as a new enveloped RNA virus; 3) reproducing the disease experimentally with the isolated Lelystad virus; 4) isolating the virus from the experimentally induced disease.     

Effects of growth curve parameters on cow efficiency.

Weight-age data from 50 Retinta beef cows from 8 to 97 mo of age located in southwestern Spain were fitted to von Bertalanffy, Brody, and Richards functions to determine the relationship between growth curve parameters and cow efficiency. Only cows having at least 31 weights were included in the analysis. Von Bertalanffy, Brody, and Richards functions were fitted to weights of each cow. Relevant parameters of the three functions are A and K, associated with the asymptotic mature weight and rate of maturing, respectively. Criteria for comparisons among the three functions were computing difficulty, goodness of fit, and lack of bias of A. Productivity indicators were number of calves weaned during the first five calving seasons (NC), average birth weight (BWT), average weaning weight (WW), and average weaning weight per cow per year (WWY). The von Bertalanffy function was selected as the most appropriate. Least squares means for A and K were 650 +/- 8.17 kg and .038 +/- .001 mo-1, respectively. The values of NC, BWT, WW, and WWY were 4.0 +/- .11 calves, 38.2 +/- .4 kg, 218 +/- 5 kg, and 172 +/- 5 kg, respectively. Regression analysis for A indicated a decrease in NC when mature weight increased (P less than .05). There was a nonsignificant trend for heavier cows (higher A) to have calves with heavier BWT or WW. The value of WWY increased (P less than .05) with increased maturing rate (K) of cows. No significant associations were found between K and BWT or WW.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasmid and restriction endonuclease patterns in Pasteurella multocida isolated from a swine pyramid.

Restriction endonuclease analysis (REA) and plasmid profile were used to study the epidemiology of Pasteurella multocida in a swine pyramid structure. The studied pyramid was comprised of a group of 12 swine farrow-to-finish farms related by unidirectional animal movement. P. multocida isolates were obtained from the lungs of 275 slaughtered pigs. Serotyping was performed by hyaluronidase sensitivity test and toxicity was investigated by the ELISA test. HpaII was used to cleave the P. multocida extracted DNA. REA patterns relationships were studied using the Sokal-Michener coefficients, and the dendrogram was built using the UPGMA system. The 218 P. multocida isolates obtained were distributed in 17 REA patterns. In 9 of the 12 farms studied only 2-3 REA patterns were detected, with one clearly predominant pattern. The 81 strains with plasmids were assigned to six plasmid profiles. REA and plasmid profiles proved to be good epidemiological tools for identifying different strains of P. multocida with the same phenotype.     

Distribution of Ilex and Juniperus roots in three container-media

Ilex crenata Thunb. cultivar ‘Green Luster’ and Juniperus horizontalis Moench. cultivar ‘Plumosa’ were grown in 3 container-media for 13 months. The container-media were dissected by 2 horizontal cuts to yield 3 depth zones, 3 equal concentric areas were outlined on the lower surface of each depth zone and root distribution determined. A greater number of Ilex roots were in the 2 inside concentric areas of the bottom two-thirds of the peat:perlite medium than in the same divisions of soil:peat:sand and pine bark:sand media. Juniperus roots were more evenly distributed through the depth zones of pine bark: sand than soil:peat:sand or peat:perlite media.     

Tetrachloroanisol: a source of musty taste in eggs and broilers

Ingestion by hens and broilers of specific chloroanisols present in some wood shavings used in poultry cages can result in a musty taste in poultry products.     

Comparative study of the effect of the effect of carbadox, olaquindox and cyadox on aldosterone, sodium and potassium plasma levels in weaned pigs

To study the effects of olaquindox and cyadox on aldosterone, sodium and potassium in the blood in comparison with the effects of carbadox, weaned pigs were fed these compounds in different doses. Pigs treated with 100 and 200 ppm carbadox showed a significant decline of aldosterone after five and three weeks, respectively, compared with control values. In the 200 ppm group treatment was interrupted at week 4. With olaquindox a continuous, significant decline was found from 50 ppm and above after five weeks, and from 25 ppm and above (but excluding the 100 ppm group), after six weeks. In the cyadox groups a significant decline was measured after six weeks in the 50, 200 and 400 ppm groups. Only the 200 ppm group had an earlier response at three and five weeks. A decrease of sodium to hyponatraemic levels in the carbadox groups was seen after three weeks in the 200, and after five weeks in the 100 ppm group. In the olaquindox groups only the 200 ppm dosage showed a consistent decrease to hyponatraemic levels from four weeks treatment. In the cyadox groups the 200 ppm dosage reached a hyponatraemic level after six weeks. An increase of potassium to hyperkalaemic levels occurred at 100 and 200 ppm carbadox dosage after four and three weeks, respectively, and at 200 ppm olaquindox dosage after four weeks. No hyperkalaemic levels were seen in the cyadox groups. It is concluded that the toxic effect of olaquindox, despite minor differences, is comparable with that of carbadox but that cyadox is less toxic.