氨基酸在北美家禽饲料中的使用

L-赖氨酸在北美市场中得到了广泛地使用,使用率已突破90％。L-苏氨酸也正在被迅速地使用,2000～2006年北美市场份额大量增长,味之素占北美及全球市场份额的70％。2004～2006年,北美洲家禽饲料中苏氨酸的使用增长率达到127．5％．     

A Comparison of Simple Continuous Versus Simple Interrupted Suture Patterns for Tracheal Anastomosis After Large-Segment Tracheal Resection in Dogs

Two suture techniques for tracheal anastomosis after large-segment tracheal resection were compared. Eight cartilages were resected from the trachea of each of 12 dogs; anastomoses with 4-0 polydioxanone suture were created using a simple continuous suture technique in six dogs and a simple interrupted suture technique in six dogs. Surgical time was shorter but apposition of tracheal segments at the time of surgery was less precise with the simple continuous suture technique. The dogs were evaluated for 150 days after surgery. Clinical abnormalities after tracheal resection and anastomosis were not observed. Percent dorsoventral luminal stenosis was calculated by measuring the tracheal lumen diameter on lateral cervical radiographs. Percent luminal stenosis was calculated planimetrically using a computerized digitizing tablet. Anastomotic stenosis was mild in all dogs; however, the mean percent luminal stenosis determined planimetrically was significantly greater for dogs that had the simple continuous suture technique. Planimetric measurements of cross-sectional area made before and after formalin fixation were not significantly different. Radiographic determination of percent dorsoventral luminal stenosis was a poor predictor of diminution of cross-sectional area determined planimetrically.     

Experimental reproduction of severe disease in CD/CD pigs concurrently infected with type 2 porcine circovirus and porcine reproductive and respiratory syndrome virus

Three-week-old cesarean-derived colostrum-deprived (CD/CD) pigs were inoculated with porcine circovirus type 2 (PCV2, n = 19), porcine reproductive and respiratory syndrome virus (PRRSV, n = 13), concurrent PCV2 and PRRSV (PCV2/PRRSV, n = 17), or a sham inoculum (n = 12) to compare the independent and combined effects of these agents. Necropsies were performed at 7, 10, 14, 21, 35, and 49 days postinoculation (dpi) or when pigs became moribund. By 10 dpi, PCV2/PRRSV-inoculated pigs had severe dyspnea, lethargy, and occasional icterus; after 10 dpi, mortality in this group was 10/11 (91%), and all PCV2/ PRRSV-inoculated pigs were dead by 20 dpi. PCV2-inoculated pigs developed lethargy and sporadic icterus, and 8/19 (42%) developed exudative epidermitis; mortality was 5/19 (26%). PRRSV-inoculated pigs developed dyspnea and mild lethargy that resolved by 28 dpi. Microscopic lesions consistent with postweaning multisystemic wasting syndrome (PMWS) were present in both PCV2- and PCV2/PRRSV-inoculated pigs and included lymphoid depletion, necrotizing hepatitis, mild necrotizing bronchiolitis, and infiltrates of macrophages that occasionally contained basophilic intracytoplasmic inclusion bodies in lymphoid and other tissues. PCV2/ PRRSV-inoculated pigs also had severe proliferative interstitial pneumonia and more consistent hepatic lesions. The most severe lesions contained the greatest number of PCV2 antigen-containing cells. PRRSV-inoculated pigs had moderate proliferative interstitial pneumonia but did not develop bronchiolar or hepatic lesions or lymphoid depletion. All groups remained seronegative to porcine parvovirus. The results indicate that 1) PCV2 coinfection increases the severity of PRRSV-induced interstitial pneumonia in CD/CD pigs and 2) PCV2 but not PRRSV induces the lymphoid depletion, granulomatous inflammation, and necrotizing hepatitis characteristic of PMWS.     

Genetic monitoring of ex situ African Penguin (Spheniscus demersus) populations in South Africa

The African Penguin (Spheniscus demersus) has suffered population declines and is listed in the IUCN Red List as Endangered. The species is endemic to the coast of southern Africa, and breeding colonies are distributed on the south-western coast of Africa. Currently, African Penguins are being kept in zoo and aquarium facilities throughout South Africa. In this study, molecular genetic data based on 12 microsatellite markers from 1 119 African Penguin samples from four facilities were generated in order to determine the level of genetic variation, population structure and differentiation, and effective population size to assist in the development of an effective captive management plan. Expected heterozygosity ranged from 0.57 to 0.62, and allelic richness from 4.2 to 5.1. However, based on differences between first- and second-generation captive birds, we conclude that the ex situ population is at risk of losing genetic variability in the future and management programmes should include exchange of birds between captive facilities in order to induce gene flow and increase effective population size. Adding individuals from in situ populations should also be considered in the future in cases where these birds cannot be rehabilitated. Molecular genetic analyses of wild penguin populations should be carried out for comparison, and to ascertain to what degree ‘in situ genetic diversity’ is represented among ex situ populations. With regular resampling and analyses, the extent of the effect of processes such as genetic drift on diversity in the ex situ penguin populations will become evident.     

Morphologic and biochemical characterization of hyperextension of the metacarpophalangeal and metatarsophalangeal joints in llamas

OBJECTIVE: To determine the morphologic and biochemical characteristics of hyperextension of the metacarpophalangeal and metatarsophalangeal joints in llamas. ANIMALS: 12 adult llamas (6 with bilateral hyperextension of the metacarpophalangeal or metatarsophalangeal joints and 6 age- and sex-matched control llamas). PROCEDURES: Llamas were evaluated by use of lameness examination, ultrasonography, and radiography. A CBC, serum biochemical analysis, and determination of concentrations of trace minerals in serum and liver samples were performed. Llamas were euthanized, and samples of the superficial digital flexor tendon, deep digital flexor tendon, and suspensory ligament were obtained from 4 areas and snap-frozen in liquid nitrogen or suspended in neutral-buffered 10% formalin. Immunohistochemical evaluation of collagen types I and III and assays for measurement of lysyl oxidase activity were performed. RESULTS: 2 affected llamas had a visible gait deficit associated with metacarpophalangeal joint hyperextension. Radiographic evidence of osteoarthritis was detected in 1 severely affected llama, and ultrasonographic changes of soft tissue mineralization and suspensory desmitis were observed in 2 llamas. Liver concentrations of copper were lower and serum concentrations of zinc higher in affected llamas, compared with values in control llamas. Lysyl oxidase activity and collagen distribution did not differ significantly between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Hyperextension of the metacarpophalangeal or metatarsophalangeal joints in llamas does not appear to be the result of injury or degeneration of the suspensory ligament or flexor tendons. Lower copper concentrations coupled with higher zinc concentrations in affected llamas may be indicative of secondary copper deficiency.     

Ace and ace-like genes of invasive redlegged earth mite: copy number variation,target-site mutations,and their associations with organophosphate insensitivity

Background

Invasive Australian populations of redlegged earth mite, Halotydeus destructor (Tucker), are evolving increasing organophosphate resistance. In addition to the canonical ace gene, the target gene of organophosphates, the H. destructor genome contains many radiated ace-like genes that vary in copy number and amino acid sequence. In this work, we characterise copy number and target-site mutation variation at the canonical ace and ace-like genes and test for potential associations with organophosphate insensitivity. This was achieved through comparisons of whole-genome pool-seq data from alive and dead mites following organophosphate exposure.

Results

A combination of increased copy number and target-site mutations at the canonical ace was associated with organophosphate insensitivity in H. destructor. Resistant populations were segregating for G119S, A201S, F331Y at the canonical ace. A subset of populations also had copy numbers of canonical ace > 2, which potentially helps overexpress proteins carrying these target-site mutations. Haplotypes possessing different copy numbers and target-site mutations of the canonical ace gene may be under selection across H. destructor populations. We also detected some evidence that increases in copy number of radiated ace-like genes are associated with organophosphate insensitivity, which might suggest potential roles in sequestration or breakdown of organophosphates.

Conclusion

Different combinations of target-site mutations and (or) copy number variation in the canonical ace and ace-like genes may provide non-convergent ways for H. destructor to respond to organophosphate selection. However, these changes may only play a partial role in organophosphate insensitivity, which appears to have a polygenic architecture. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.