Neonatal lamb mortality: major risk factors and the potential ameliorative role of melatonin     

Tom Flinn  David O.Kleemann  Alyce M.Swinbourne  Jennifer M.Kelly  Alice C.Weaver  Simon K.Walker  Kathryn L.Gatford  Karen L.Kind  William H.E.J.van Wettere 《畜牧与生物技术杂志(英文版)》2021,(2):451-461

High incidences of pre-weaning mortality continue to limit global sheep production, constituting a major economic and welfare concern. Despite significant advances in genetics, nutrition, and management, the proportion of lamb deaths has remained stable at 15–20% over the past four decades. There is mounting evidence that melatonin can improve outcomes in compromised ovine pregnancies via enhanced uterine bloodflow and neonatal neuroprotection. This review provides an overview of the major risk factors and underlying mechanisms involved in perinatal lamb mortality and discusses the potential of melatonin treatment as a remedial strategy. Supplementing pregnant ewes with melatonin enhances uterine bloodflow and fetal oxygenation, and potentially birthweight and neonatal thermogenic capacity. Melatonin freely crosses the ovine placenta and blood-brain barrier and provides neuroprotection to the fetal lamb during periods of chronic and acute hypoxia throughout gestation, with improved behavioural outcomes in hypoxic neonates. The current literature provides strong evidence that maternal melatonin treatment improves outcomes for lambs which experience compromised in utero development or prolonged parturition, though to date this has not been investigated in livestock production systems. As such there is a clear basis for continued research into the effects of maternal melatonin supplementation during gestation on pre-weaning survival under extensive production conditions.  相似文献   

Off-axis crustal thickness across and along the east pacific rise within the MELT area   总被引：1，自引：0，他引：1  

JP Canales  RS Detrick  S Bazin  AJ Harding  JA Orcutt 《Science (New York, N.Y.)》1998,280(5367):1218-1221

Wide-angle seismic data along the Mantle Electromagnetic and Tomography (MELT) arrays show that the thickness of 0.5- to 1. 5-million-year-old crust of the Nazca Plate is not resolvably different from that of the Pacific Plate, despite an asymmetry in depth and gravity across this portion of the East Pacific Rise. Crustal thickness on similarly aged crust on the Nazca plate near a magmatically robust part of the East Pacific Rise at 17 degrees15'S is slightly thinner (5.1 to 5.7 kilometers) than at the 15 degrees55'S overlapping spreading center (5.8 to 6.3 kilometers). This small north-south off-axis crustal thickness difference may reflect along-axis temporal variations in magma supply, whereas the across-axis asymmetry in depth and gravity must be caused by density variations in the underlying mantle.  相似文献   

Management of bilateral flexural deformity of the metacarpophalangeal joints in three alpaca crias     

T CASHMAN  AJ DART  A O''SHEA  DR HODGSON 《Australian veterinary journal》1999,77(8):508-510

Three neonatal alpacas were treated for MCP flexural deformities. Two crias responded well to conservative therapy using splints made from fibreglass cast material. One cria with severe deformity failed to respond to conservative treatment but recovered satisfactorily after transection of the suspensory ligament in both legs. It seems that mild cases of flexural deformity of the MCP joint in alpaca crias respond well to conservative therapy but that surgical correction may be required in more severe cases. Sequential transection of the structures limiting extension of the MCP joint may result in fewer complications than previously reported techniques.  相似文献   

Cloning and sequencing of the ovine gamma-interferon gene   总被引：1，自引：0，他引：1  

AJ RADFORD  ALM HODGSON  JS ROTHEL  PR WOOD 《Australian veterinary journal》1991,68(3):82-84

Cytokines are major modulators of the immune system of all animals. The cloning and expression of recombinant cytokine genes have permitted the analysis of their immune function and role in the control of the immune response to disease and vaccination. While human, murine, and bovine genes have been cloned and sequenced, the cloning of ovine cytokine genes has not yet been reported. As sheep are of dominant economic importance to the Australian farming industry, it is of significance to clone and express these genes to facilitate the development of new and better vaccines and pharmaceuticals. We have initially selected ovine gamma-interferon (gamma-IFN) as a target cytokine gene. By the use of the polymerase chain reaction (PCR), using primers based on the bovine gamma-interferon sequence, we have amplified the ovine gamma-interferon gene from crude messenger RNA extracted from lymphocytes. After cloning and DNA sequencing the gene, we found that ovine gamma-IFN is 93% identical to bovine gamma-IFN in amino acid sequence. This result indicates that the PCR method will be a rapid and efficient means for cloning other ovine cytokine genes.  相似文献   

Effects of parasitism and of supplementing ewes with methyl methionine hydroxy analogue on the wool production of their lambs as adults     

JL WHEELER  AJ WILLIAMS  WH SOUTHCOTT 《Australian veterinary journal》1988,65(11):358-359

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Does Apoptosis Occur during Follicular Atresia in the Follicular Walls of the Porcine Ovary?     

K. Derecka  H. Kalamarz  AJ. Ziecik 《Reproduction in domestic animals》1995,30(1):32-35

Contents In this experiment, the possibility that the follicular-wall cells' death during ovarian follicular atresia occurs as a result of apoptosis was examined. Programmed cell death or apoptosis is a process whereby cells die in a controlled fashion, triggered by changes in levels of specific physiological stimuli. Morphological transformations of the cells are preceded by endo- nuclease-mediated genomic-DNA cleavage. The analysis of DNA from the theca and granulosa layers of follicles indicated that internucleosomal fragmentation of DNA occurred in atretic granulosa cells but not in atretic theca cells. The healthy granulosa and theca cells in all classes of follicles showed no apoptosis. This paper demonstrates that the death of porcine ovarian-follicle walls can be caused by different processes and, contrary to granulosa cells' apoptosis, either does not or only partly concerns the internal theca layer.  相似文献   

The isolation of salmonellas from piggery waste water after orthodox pondage treatment   总被引：2，自引：0，他引：2  

DP HENRY  AJ FROST  D. O'BOYLE  RDA CAMERON 《Australian veterinary journal》1995,72(12):478-479

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Recent developments in diagnosis of exotic disease at the Australian Animal Health Laboratory     

AJ FORMAN 《Australian veterinary journal》1993,70(5):161-163

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An outbreak of haemorrhagic septicaemia associated with Pasteurella multocida subsp gallicida in a large pig herd     

RDA CAMERON  D. O'BOYLE†  AJ FROST†  AN GORDON†  N. FEGAN‡ 《Australian veterinary journal》1996,73(1):27-29

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Veterinarians and the promotion of food safety on the farm     

AJ Turner 《Australian veterinary journal》1997,75(6):416-416

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