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排序方式: 共有125条查询结果,搜索用时 125 毫秒
61.
S Ranjan C Trudeau R K Prichard R von Kutzleben D Carrier 《Veterinary parasitology》1992,41(3-4):227-231
The efficacy of moxidectin, a new endectocide against natural nematode infections, was evaluated. Twenty-five calves were divided into two groups of eight calves each and a third group of nine calves. Moxidectin was administered s.c. to two groups (I, 0.2 mg kg-1 body weight (BW); II, 0.3 mg kg-1 BW) and the third group (III) received the vehicle (placebo) s.c. Two pre-treatment and one post-treatment faecal nematode egg count determinations were made from all calves, and they were necropsied 2 weeks after treatment for the identification and enumeration of nematode parasites. Group III calves, which received the drug-free vehicle, harboured eight species of nematodes (Ostertagia ostertagi, Trichostrongylus axei, Cooperia oncophora, Cooperia punctata, Nematodirus helvetianus, Trichuris discolor, Oesophagostomum radiatum and Dictyocaulus viviparus). The mean total worm burden for this group was 8935. There was a significant reduction in the numbers of many species of nematodes (Ostertagia, Trichostrongylus, Cooperia and Nematodirus) in both treated groups. Cooperia oncophora was reduced by 94% in Group I and by 96% in Group II, while all other nematode species were reduced by 99%. Immature stages of Ostertagia and Nematodirus were significantly reduced in the two treated groups. Two weeks after treatment, the mean faecal egg counts of both treated groups were reduced by more than 98%. There was no significant difference in mean total worm burdens or egg counts between the two treated groups. 相似文献
62.
Maya blue paint was often used in Mesoamerica. The origin of its color and its resistance to acids and biocorrosion have not been fully understood. High-resolution transmission electron microscopy, electron energy loss spectroscopy, and x-ray microanalysis studies of authentic samples show that palygorskite crystals in the paint form a superlattice that probably occurs as a result of mixing with indigo molecules. An amorphous silicate substrate contains inclusions of metal nanoparticles encapsulated in the substrate and oxide nanoparticles on the surface. The beautiful tone of the color is obtained only when both the particles and the superlattice are present. 相似文献
63.
A Torres J Chagas e Silva MC Deloche P Humblot AEM Horta L Lopes‐da‐Costa 《Reproduction in domestic animals》2013,48(4):643-650
Using a novel in vivo model considering a low developmental competence embryo (demi‐embryo) and a subnormal fertility recipient (lactating high‐yielding dairy cow), this experiment evaluated the effect of human chorionic gonadotrophin (hCG) treatment at embryo transfer (ET) on embryonic size at implantation, embryonic survival and recipient plasma progesterone (P4) and bovine pregnancy‐specific protein B (PSPB) concentrations until day 63 of pregnancy. Embryos were bisected and each pair of demi‐embryos was bilaterally transferred to recipients (n = 61) on day 7 of the oestrous cycle. At ET recipients were randomly assigned to treatment with 1500 IU hCG or to untreated controls. Higher (p < 0.01) pregnancy rates on days 25, 42 and 63, and embryo survival rate on day 63 were observed in hCG‐treated cows with secondary CL than in hCG‐treated cows without secondary CL and in untreated cows. Pregnancy rates and embryo survival rate were similar in hCG‐treated cows without secondary CL and untreated cows. Embryonic size on day 42 was not affected by treatment with hCG, presence of secondary CL and type of pregnancy (single vs twin). Presence of secondary CL increased (p < 0.05) plasma P4 concentrations of pregnant cows on days 14, 19 and 25 but not thereafter and of non‐pregnant cows on days 14–21. Treatment with hCG and presence of secondary CL had no effect on plasma PSPB concentrations, which were higher (p < 0.05) in twin than in single pregnancies. In conclusion, secondary CL induced by hCG treatment at ET significantly increased plasma P4 concentrations, the survival rate of demi‐embryos and the pregnancy rate of high‐yielding lactating dairy cows. Embryos were rescued beyond maternal recognition of pregnancy, but later embryonic survival, growth until implantation and placental PSPB secretion until day 63 of pregnancy were not affected by treatment or presence of secondary CL. 相似文献
64.
65.
M Pande GK Das FA Khan M Sarkar JK Prasad MC Pathak H Kumar 《Reproduction in domestic animals》2013,48(1):79-84
The effect of uterine infection on size and follicular fluid composition of the largest follicle was studied in buffalo. Reproductive tracts were collected from 102 graded Murrah buffaloes at an abattoir. Uterine infection was diagnosed by physical examination of uterine mucus, white side test and uterine cytology. Samples with pus‐containing mucus, positive reaction on white side test and/or >5% neutrophils were considered to be positive for uterine infection. Diameter of the largest follicle was measured, and follicular fluid was aspirated and assayed for nitric oxide (NO), ascorbic acid (AA), cholesterol, oestradiol (E2) and progesterone (P4). Infected buffaloes had smaller‐sized (p < 0.0001) largest follicles than non‐infected buffaloes. Follicular fluid collected from the largest follicle in infected buffaloes had greater (p < 0.0001) NO and P4 concentrations coincident with lesser AA (p < 0.001), cholesterol (p < 0.0001) and E2 (p < 0.0001) concentrations. Results indicated that uterine infection has an inhibitory effect on growth of the largest follicle in buffalo. The changes in follicular fluid composition in infected buffaloes suggest that the direct effect of uterine infection on ovarian function may be mediated through an alteration in the follicular microenvironment. Greater NO and lesser AA concentrations in the follicular fluid of infected animals are novel findings. 相似文献
66.
MC Lucy 《New Zealand veterinary journal》2013,61(6):406-415
Dairy cattle have traditionally been selected for their ability to produce milk and milk components. The traditional single-minded approach to selection of dairy cattle has now changed and secondary traits are being included in selection indices by decreasing the emphasis on production. Greater emphasis on non-production traits reflects the industry's desire for functional dairy cattle. Six broad categories of non-lactational traits are discussed in this review. They are: type; growth, body size and composition; efficiency of feed utilisation; disease resistance, e.g. udder health as measured by somatic cell score; reproduction; and management. Most of these traits can be found within selection indices worldwide, although relative emphasis varies. The non-lactational traits mentioned above are quantitative, meaning that the phenotype in the whole animal represents the sum of lesser traits that cannot be easily measured. The physiological mechanisms that underlie quantitative traits are extremely complex. Genetic selection can be applied to quantitative traits but it is difficult to link successful genetic selection with the underlying physiological mechanisms. The importance that the bovine genome sequence will play in the future of the genetics of dairy cattle cannot be understated. Completing the bovine genome sequence is the first step towards modernising our approach to the genetics of dairy cattle. Finding genes in the genome is difficult and scanning billions of base pairs of DNA is an imperfect task. The function of most genes is either unknown or incompletely understood. Combining all of the information into a useable format is known as bioinformatics. At the present time, our capacity to generate information is great but our capacity to understand the information is small. The important information resides within subtle changes in gene expression and within the cumulative effect that these have. Traditional methods of genetic selection in dairy cattle will be used for the foreseeable future. Most non-lactational traits are heritable and will be included in selection indices if the traits have value. The long-term prognosis for genome science is good but advances will take time. Genetic selection in the genome era will be different because DNA sequence analysis may replace traditional methods of genetic selection. 相似文献
67.
Leaf‐cutting ants are generally recognized as important pest species in Neotropical America. They are eusocial insects that exhibit social organization, foraging, fungus‐cultivation, hygiene and a complex nest structure, which render their management notoriously difficult. A lack of economic thresholds and sampling plans focused on the main pest species preclude the management of leaf‐cutting ants; such management would facilitate their control and lessen insecticide overuse, particularly the use of insecticidal baits. Recent restrictions on the use of synthetic compounds for such purposes impose additional challenges for the management of leaf‐cutting ants. Considerable effort has been exerted regarding these challenges, which are addressed herein, but which also remain challenges that are yet to be conquered. © 2013 Society of Chemical Industry 相似文献
68.
Luteal activity and effect of dietary energy restriction on follicular development in lactating cows 下载免费PDF全文
A Comin T Peric M Montillo A Cappa V Marchi MC Veronesi A Prandi 《Reproduction in domestic animals》2017,52(4):632-639
The aim of this research has been to evaluate the presence of anomalies in the ovarian cycle activity during postpartum and to verify whether 72‐hr dietary fasting during the dominance phase, the phase before ovulation, might modify the ovarian follicle population. The presence of anomalies in ovarian cycle activity has been evaluated in 30 Italian Friesian cows starting from 20 days postpartum until 211 days of lactation. Long oestrus and brief dioestrus or scarce luteal activity have been the main anomalies found through measuring progesterone concentrations in the whey. Until 100 days of lactation, the BCS values of the problematic animals have been significantly lower than those in animals with normal ovarian activity. After 100 days of lactation, the ovarian anomalies continued to appear despite the fact that all the animals have reached comparable BCS values. Starting from the results of this trial, the effect of 72‐hr dietary fasting on dominant follicles has been studied in six cows. Ultrasonography revealed that the diameter of the follicles at 71 days postpartum has been significantly lower than at 181 days. A 72‐hr dietary restriction at 101 and 211 days postpartum did not affect the size of the dominant follicle. However, at 101 days postpartum, half of the animals presented follicular cysts. The effect of fasting differed if the animal has been in early postpartum or 211 days of lactation. Further researches are necessary to understand how different metabolic conditions can modify the follicular population but on the other hand the study shows the utility for farmers and field veterinarians of monitoring the resumption of the ovarian cycle postpartum through the whey progesterone concentrations. 相似文献
69.
C Ortega‐Ferrusola MC Gil H Rodríguez‐Martínez L Anel FJ Peña P Martín‐Muñoz 《Reproduction in domestic animals》2017,52(6):921-931
Techniques such as mass spectrometry have led to unprecedented knowledge of the proteins that are present in the spermatozoa of humans and other mammals. However, in spite of their high‐throughput and fractioning techniques, most of the techniques in use only offer average values for the entire sperm population. Yet, ejaculate is very heterogeneous, and average values may mask relevant biological information.The application of flow cytometry may overcome this disadvantage, allowing proteomic analysis at the single‐cell level. Moreover, recent advances in cytometry, allowing multiple analyses within a single cell combined with powerful statistical tools, as an expanding subfield in spermatology, are described. The increased use of advanced flow cytometers in andrology laboratories will allow the rapid development of multiparametric, multicolour flow cytometry in andrology that will expand the clinical applications and research possibilities of flow cytometry‐based proteomic approaches, especially in the subfields of clinical andrology and sperm biotechnology. 相似文献
70.
Eight adult Landrace boars were housed for 12 mo in one of two social environments. Socially nonrestricted boars were penned adjacent to and allowed minimal physical contact with ovariectomized gilts hormonally induced into estrus every 2 wk. Socially restricted boars were penned behind solid walls to eliminate visual and physical contact with other pigs. All animals were subjected to natural changes in daylength. Semen was collected weekly; gel-free volume, gel weight, sperm concentration and number per ejaculate, sperm motility (percent and type) and semen pH were determined. Total protein, citric acid contents and alkaline phosphatase activity were measured in seminal plasma. Testis length and width and various body temperature measurements were recorded monthly. Except for percent motile sperm and alkaline phosphatase activity, all semen characteristics varied (P less than .05) with month. The pattern of seasonal change in semen volume was modified by social environment (group X month, P less than .05). Sperm numbers were highest in winter and lowest in spring and summer. Ejaculate protein and citric acid contents were highest in fall and winter; decreases in spring were associated with moderate ambient temperatures and increases in daylength (r = -.80, P less than .05). Testicular length for socially nonrestricted boars was maximum in November through January and minimum in April through July, and did not vary as extensively for socially restricted boars. Scrotal temperature was elevated during periods of high ambient temperature, but not to values detrimental to spermatogenic function.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献