Transmission of bovine viral diarrhea virus to adult goats from persistently infected cattle.

The transmission of bovine viral diarrhea virus (BVDV) from persistently infected (PI) heifers to adult seronegative goats was examined in this study. Ten seronegative adult goats were exposed to 4 PI heifers. None of the goats developed any clinical signs but all goats seroconverted by 42 days after exposure to the PI cattle. Results indicate that goats are susceptible to BVDV infection when housed with PI cattle.     

Susceptibility of dogs to infection with Ehrlichia chaffeensis, causative agent of human ehrlichiosis.

Ehrlichia chaffeensis, the newly recognized agent of human ehrlichiosis, is closely related to E canis, the causative agent of canine ehrlichiosis. Eight pups were inoculated IV with E chaffeensis-, or with E canis-infected DH82 cells, or organisms released from these host cells. Two additional pups served as nonexposed controls. Marked thrombocytopenia was observed in the E canis-infected pups, but not in those infected with E chaffeensis. Homologous serologic response was observed in the E chaffeensis-exposed pups by postinoculation day (PID) 14 and in the E canis-exposed pups by PID 21. Ehrlichia chaffeensis and E canis were reisolated from the respective inoculated pups on each of 8 attempts from PID 7 to 26. One E chaffeensis-exposed pup that was challenge exposed with E canis via blood transfusion, developed fever, anorexia, and thrombocytopenia, suggesting lack of cross protection against E canis.     

养猪生产中替代传统的抗菌促生长剂的添加剂策略

抗生素自20世纪50年代早期开始被用作生长促进剂(Hays,1977)。使用抗生素来改善猪只的生长速率和生长效率的效果已经被大量研究所证实(Cromwell和Dawson,1990)。抗生素的反应很不稳定,但可改善动物的生产性能和体况。近期,对约12000个试验进行的总结中,72％以上的试验可以看出在家畜和家禽日粮中添加生长促进剂可提高产出量(Rosen,1996)。Cromwell(1991)报告说,农场中饲喂抗生素可改善猪日增重平均为26％,减少饲料需求19％。在生产性能     

ASAS Centennial Paper: Impact of animal science research on United States goat production and predictions for the future

Goat research in the United States has increased but at a rate less than that in production. Research on goat meat includes nutritional quality, packaging, color, sensory characteristics, and preslaughter management. Goat skins have value for leather, but quality of goat leather has not been extensively studied. Research in the production, quality, antibiotic residues, and sensory characteristics of goat milk and its products has aided development of the US dairy goat industry. Limited progress has been made in genetic improvement of milk or meat production. There is need to explore applications of genomics and proteomics and improve consistency in texture and functionality of goat cheeses. New goat meat and milk products are needed to increase demand and meet the diverse tastes of the American public. Despite research progress in control of mohair and cashmere growth, erratic prices and sale of raw materials have contributed to further declines in US production. Innovative and cooperative ventures are needed for profit sharing up to the consumer level. Internal parasites pose the greatest challenge to goat production in humid areas largely because of anthelmintic resistance. Study of alternative controls is required, including immunity enhancement via nutrition, vaccination, pasture management such as co-grazing with cattle, and genetic resistance. Similarly, the importance of health management is increasing related in part to a lack of effective vaccines for many diseases. Nutrition research should address requirements for vitamins and minerals, efficiencies of protein utilization, adjusting energy requirements for nutritional plane, acclimatization, and grazing conditions, feed intake prediction, and management practices for rapid-growth production systems. Moreover, efficient technology transfer methods are needed to disseminate current knowledge and that gained in future research.     

The demonstration of maedi/visna virus in sheep in Great Britain.

A virus indistinguishable from that causing maedi/visna has been isolated from a sheep flock in Great Britain. The virus was identified in cell cultures using immunofluorescent and electron microscopical techniques. The complement fixation test and the agar gel immunodiffusion test were used to assess the proportion of serological reactors within the flock. There has been no evidence of clinical disease in the flock into which foreign imports were introduced in the years prior to 1976.     

PrP genotype progression in flocks participating in the National Scrapie Plan for Great Britain

The National Scrapie Plan (NSP) for Great Britain is a voluntary scheme that, through PrP genotype testing and restricted breeding, aims to reduce the risk of scrapie in the national sheep flock. To gauge the progress in member flocks and within breeds, the genotype profile of successive crops of ram lambs was monitored between 2002 and 2004. In each of the 11 most frequently sampled breeds, the proportion of ram lambs testing in the most resistant genotype category (NSP type 1: ARR/ARR) increased, and there was a reduction in the proportion of genotypes associated with the highest disease risk, that is X/VRQ, where X is an allele other than ARR. Changes in the proportion of ram lambs testing for ARR-heterozygous genotypes (NSP type 2: ARR/X, where X is not VRQ) appeared to be influenced by whether the sheep were hill breeds or non-hill breeds. In each of six frequently sampled hill breeds these genotypes expanded, in relative terms, whereas they declined in four of five prominent lowland/crossing breeds. The proportion of ram lambs that carried neither ARR nor VRQ (NSP type 3) declined consistently in the top 11 breeds, but there was little change in the ARR/VRQ genotype (NSP type 4). Among individual flocks that had ram lambs tested in all three years 2002 to 2004, the majority experienced an increase in the proportion testing ARR/ARR, and of those that had VRQ ram lambs in 2002, most recorded a decrease in their frequency by 2004.     

Effect of water restriction and dietary sodium on nutrient metabolism in lambs

Twenty-four Hampshire X Suffolk wether lambs (40 kg) were used in 2 X 2 factorial arrangement of treatments to study the influence of water restriction and high levels of dietary Na on nutrient utilization. Lambs were offered either a normal Na diet (.20% Na) or a high Na diet (1.77% Na). Additionally, the lambs were offered either a normal quantity of water (previously determined voluntary intake of lambs fed normal Na levels) or were restricted to a water intake 80% of normal. Each lamb received 800 g/d of a hay-corn diet (77.5% fescue hay) with an additional 38 g of NaCl offered to lambs on high Na treatments. The complete experiment consisted of 14 d of adjustment and 7 d of total collection with blood and ruminal characteristics measured on the last day of the collection period. A high Na intake decreased (P less than .05) the apparent digestibility of neutral detergent fiber, but tended to increase the apparent absorption of Mg. Plasma urea N concentrations were not affected (P greater than .05) by level of Na or water intake. Plasma Na and K concentrations were not affected (P greater than .05) by treatment regimen. A high Na intake increased (P less than .05) plasma Mg concentrations at 6 h post-feeding with a normal level of water intake, but decreased (P less than .05) Mg concentrations at 6 h with restricted water intake. Ruminal ammonia N and K concentrations at 2 h post-feeding were decreased (P less than .05) by a high level of dietary Na. Ruminal Na concentration was not affected (P greater than .05) by treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Carbohydrate dynamics in kiwifruit

Summary

Rates of fruit growth, on-vine changes in the soluble and insoluble carbohydrate pools, and subsequent changes during storage were examined on kiwifruit from vines having moderate to very high crop loads (20–50 fruit m^?2). In accord with previous studies, vines carrying the highest loads exhibited a 18% decrease in mean fruit weight and a two-fold increase in total yield compared with those having the lowest crop loads. Rates of dry-matter accumulation in the fruit varied in proportion to total yield and remained constant over the entire season – a result that deserves further investigation. Effects of crop loading on the carbohydrate composition of fruit were small and after reviewing the available literature we conclude that the primary determinants of fruit composition are genetic and climatic. Relationships between the various fruit quality variables were used to develop a predictive model of soluble solids concentration of fruit at eating ripeness from harvest measurements of fruit density (weight per unit volume) or dry matter. The accuracy of these predictions are of the order of 1% (w/v). The rate of change in soluble solids during storage at 0°C is shown to follow a simple exponential function of time with a time constant of 20 d.