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91.
This paper provides an overview of the changes in the pasture-based dairy systems of New Zealand and Australia that may influence the health of cattle. There are relatively few available data that can be used to quantify the effects of increased intensification of milk production on the health of cattle. There is evidence that increased production increases the risk of mastitis and culling for udder health. Increased risks of mastitis with treatment with somatotropin support these findings; however, the risk of mastitis may decrease with increased milking frequency. Larger herds with greater stocking density should increase the risk for infectious disease, but evidence to support this contention is sparse. Very intensive grazing patterns associated with higher grass yields achieved using better cultivars and greater use of fertilisers favour nematode parasites. There is some evidence of anthelmintic resistance in both nematodes and liver fluke. Veterinarians will need to be aware of the potential for these to reduce the productivity of cattle. There have been benefits of improved nutrition on the efficiency of energy use for dairy production. Diseases such as bloat and ketosis appear to be of lower prevalence. It also appears that mineral nutrition of pasture-fed cattle is being better addressed, with gains in the control of milk fever, hypomagnesaemia and trace-element deficiencies. However, acidosis is a condition with a high point prevalence in pasture-based dairy systems where cows are fed supplements; one study in Australia found a point prevalence of approximately 11% of cows with acidosis. There is evidence from this study that the neutral detergent fibre (NDF) in pasture-based diets may need to be higher than 30% of the diet to maintain rumen stability. Laminitis and acidosis are different conditions with a similar pathogenesis, specifically highly fermentable diets. The prevalence of lameness was 28% in herds in Australia, suggesting that this condition must be a focus for preventive medical approaches, including the design of laneways, feedpads and dairies. 相似文献
92.
ABSTRACT The disease syndrome "basses richesses" (SBR) has affected sugar beet crops in Burgundy (France) since 1991. It mainly is associated with an uncultivable phloem-restricted bacterium-like organism (BLO) called SBR BLO. Transmission tests showed that field-collected Pentastiridius sp. (Hemiptera, Cixiidae) were able to transmit the SBR BLO to sugar beet. In the present work, sequences of a 1,507-bp 16S ribosomal (r)DNA fragment of SBR BLO were amplified from DNA extracts of SBR-affected field sugar beet plants, of field-collected Pentastiridius sp. plant-hoppers, and of Pentastiridiussp.-exposed sugar beet seedlings that expressed SBR symptoms. The sequences showed total identity, confirming the role of SBR BLO in the etiology of SBR and the vector role of Pentastiridius sp. Our surveys on SBR-affected sugar beet plants and Pentastiridius sp. planthoppers collected in different fields and different years suggest that a unique BLO was involved in SBR. Furthermore, comparison of 16S rDNA sequences permitted the identification of the SBR BLO as a new plant-pathogenic gamma-3 proteobacteria different from 'Candidatus Phlomobacter fragariae,' another BLO responsible for marginal chlorosis disease of strawberry in France. Phylogenetic analysis revealed a close relationship between the SBR bacterium and several bacteria described as endosymbionts of hemipteran insects. 相似文献
93.
Seasonal changes in the main biochemical components and in the condition index of cultured mussels (Mytilus galloprovincialis Lmk) from the Venice Lagoon have been followed during the period October 1979–August 1981.Carbohydrates (2–32%) show winter minima and summer maxima, while proteins (30–52%) have a rather irregular pattern. Lipids (2–13%) and condition index exhibit an annual cycle with two minima (late spring; autumn-winter) and two maxima (early spring; summer).Seasonal variations of biochemical composition and condition index are discussed in connection with the reproductive cycle and some environmental parameters such as temperature and phytoplankton availability.The comparison between the present data and those from other geographic areas confirms the peculiarity of the environment of the Venice Lagoon. 相似文献
94.
AG Bagneres MC Lorenzi G Dusticier S Turillazzi JL Clement 《Science (New York, N.Y.)》1996,272(5263):889-892
The paper wasp Polistes atrimandibularis is an obligatory social parasite of another Polistes species, P. biglumis bimaculatus. To control the host nest, the parasite sequentially changes the composition of its chemical signature, the cuticular hydrocarbons, during the colonial cycle. Gas chromatography-mass spectrometry of the cuticular hydrocarbons at every stage of the cycle showed that the parasite can switch on and off an entire chemical family, namely, the unsaturated hydrocarbons. In this way the parasite can match the host signature at a critical moment of the colonial cycle. 相似文献
95.
Summary Homozygous and heterozygous Phaseolus vulgaris and P. acutifolius parental genotypes were hybridized to determine if genotypic diversity would aid gene transfer between these species. Certain P. vulgaris female parents resulting from diverse intraspecific crosses increased the frequency of species hybrids obtained. From a total of 19 self-sterile hybrids, 20 backcross-1 (BC1) lines (P. vulgaris recurrent parent) were produced from 4 partially female-fertile hybrids, each of which had a heterozygous P. vulgaris female parent. Heterozygous P. acutifolius male parents did not influence the frequency at which interspecific hybrids could be produced but apparently improved female-fertility. Fertility of the F1BC1 generation was highly variable. The frequency of fertile individuals increased in each subsequent backcross generation (F1BC2 and F1BC3).Purdue University Agricultural Experiment Station Publication 9946. 相似文献
96.
J Santiago‐Moreno C Castaño A Toledano‐Díaz MC Esteso A López‐Sebastián SG Dávila JL Campo 《Reproduction in domestic animals》2014,49(1):134-139
It is well known that when a hen mates with multiple roosters, it is the sperm of the last male that usually fertilizes most of the eggs (‘last male precedence’). Sperm quality varies between males within a breed, but also between breeds, and thus, sperm competitiveness after mating may depend on the breeds of the roosters involved. The aim of the present work was to identify differences in sperm competitiveness between breeds, especially with respect to motility. A multibreed mating model was used. Blue Andaluza (BA) and Black Castellana (BC) hens left for 21 days with BA and BC roosters, respectively, were then left with Black‐barred Andaluza (Bb) roosters for another 21 days (experimental groups hBA‐rBC‐rBb and hBC‐rBA‐rBb). Bb roosters (as the second breed replacing the first) fertilized the majority of eggs in both the hBC‐rBA‐rBb and hBA‐rBC‐rBb groups. The percentage of offspring sired by BA roosters (8.0%) was higher (p < 0.05) than the percentage of chicks sired by BC roosters (2.1%). The fertility of the BC hens in the hBC‐rBA‐rBb group was higher (p < 0.01) than that of the BA hens in the hBA‐rBC‐rBb group. No difference in sperm concentration was seen between the breeds. Within the rapid sperm subpopulation (sperm velocity, >50 μm/s), Bb sperm showed a higher straight‐line velocity (VSL) and average path velocity (VAP) (p < 0.05) than BC sperm. The VSL and VAP values for Bb and BA sperm were similar. In conclusion, the present results show that the sperm of the BA breed, traditionally regarded as of moderate fertility, compensates for this drawback via sperm movement characteristics that afford it an advantage in competition scenarios involving males of other breeds. The VSL and VAP of the rapid sperm subpopulation may play the most important role in securing last male precedence. 相似文献
97.
98.
99.
Lalitha S Shade RE Murdock LM Hasegawa PM Bressan RA Nielsen SS 《Journal of agricultural and food chemistry》2005,53(5):1591-1597
Three recombinant soybean cysteine proteinase inhibitors (rSCPIs) L1, R1, and N2 were chemically characterized. These inhibitors have the potential to inhibit the growth and development of three major agricultural crop pests known to utilize cysteine proteinases (CPs) for protein digestion: Western corn rootworm, Colorado potato beetle, and cowpea weevil. Characterization data obtained show differences between the inhibitors and will be needed to consider the use of rSCPIs to create insect resistance in plants. 相似文献
100.
A Irsara G Bressan F Mutinelli 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1990,37(1):53-63
Epidemiological data on sylvatic rabies in Italy, during 10 years, from 1977 to 1986 are reported. This rabies epizootic expanded to all the alpine arch from Trieste to Aosta, can be divided in five different outbreaks. The good knowledge of the infected alpine area helped us in the identification of rabies outbreaks and in rabies struggle and prevention. Data from the literature on the relationship: landscape/fox/density/fox hunting/rabies have been confirmed and contributed to disease eradication. In a ten year epizootic, no human cases of rabies have been reported thanks to continuing health education and pre/post infection vaccination of persons at risk. The systemic vaccination of dogs and grazing animals and the severe struggle to stray dogs and cats reduced rabies of domestic animals to 1/10 as compared with the other European countries. Hunter's education together with valuable rewards made possible a good monitoring of sylvatic rabies diagnostic and rabies eradication after the first wave of rabies. In order to eradicate the last two rabies outbreaks, oral fox vaccination, using attenuated live vaccine, has been carried out with immediate efficacious results. 相似文献