Studies on replicating patterns of bovine sex chromosomes using 5-bromo-deoxyuridine (BrdU)

The replicating patterns of bovine sex chromosomes were examined using the method of the alternate administration of BrdU and dT throughout the DNA synthesis of the cell cycle. It was clear that two X chromosomes of the female complement behaved in a different replicating patterns and that these differences were markedly shown in the last stage of the S period. The X chromosome of the male behaved in a similar replicating pattern to one of the two female X chromosomes. It was suggested that at the beginning of the S period, the X chromosomes replicated the DNA at the end of the short arm, in the central region, and at the distal region of the long arm. It was clear that the entire Y chromosome replicated in the last S period .     

The detection of bovine herpesvirus type 1 (BHV 1) using an intradermal test. I. Field studies

An intradermal test (delayed hypersensitivity test) for the diagnosis of BHV1 infection was evaluated in 791 cattle of 16 dairy farms. The skin reactions were compared with the results of serological examinations using a commercial BHV1 ELISA kit (Trachitest). As antigen concentrated, purified and inactivated BHV1 was used. The skin reaction (increase of the skin fold thickness) was used for the interpretation of test results. The best results were obtained with the control of the skin reaction on the third day after injection of the antigen. From 393 serologically BHV1 negative cattle with an age of more than 6 months 391 (99.5%) had a skin reaction up to 1.0 mm and 2 animals (0.5%) had a reaction of 1.3 and 1.9 mm, respectively. The mean increase of skin fold thickness was 0.2 mm. Out of 291 serologically BHV1 positive cattle with an age of more than 6 months 270 had antibodies from natural infection and, partially, from additional vaccination with inactivated BHV1 vaccine. 266 (98.5%) of these animals showed a skin reaction of more than 2.0 mm, in 3 animals (1.1%) a skin reaction up to 1.0 mm was observed and 1 animal (0.4%) had a reaction of 2.0 mm. The mean increase of the skin fold thickness was 6.3 mm. 21 animals had BHV1 antibodies only because of vaccination with inactivated BHV1 vaccine. Only 4 animals had a skin reaction of more than 2.0 mm. Among 107 animals with an age up to 6 months 30 were serologically BHV1 positive and 77 were BHV1 negative. In all animals the skin reaction was less than 1.0 mm, the mean was 0.2 mm.     

桑毛虫性信息素研究 Ⅲ.性诱测报试验

采用我们自行研究合成的桑毛虫性信息素(顺—7—十八碳烯醇异戊酸酯)聚乙烯塑料诱芯进行桑毛虫发生期的测报,巳获得成功。试验结果表明,性诱发蛾进度与田间产卵进度具有极显著的相关关系,性诱蛾量能比较真实地反映田间成虫的实际发生情况.用性诱蛾量高峰日预测成虫的产卵高峰和次代幼虫的孵化高峰期,解决了性诱测报中预先无法估计50％发蛾高峰期的难题,这对指导测报和防治具有十分重要的现实意义。与传统的黑光灯诱蛾测报法比较,性诱测报具有准确性高,方法简便,成本低廉等优点,是一项值得推广的新的测报方法。     

Studies in sow reproduction: 5. The effect of lactation length of the so w on the subsequent embryonic development

The relative importance of factors causing a decrease in sow productivity with systems involving weaning of piglets under 3 weeks of age was studied. The observed reduction in litter size has been attributed to the ovulation rate or to embryo mortality. Subjects were 45 female pigs. 3 lactation lengths were tried: 7, 21, and 42 days. All sows were remated at the 1st postweaning estrus and slaughtered 20 days later to determine ovulation rate and embryo survival. All were fed 1.8 kg/day during gestation. During lactation, the feeding level was increased to a maximum of 6.3 kg/day depending on the number of piglets. Feed level from weaning to remating was 2.7 kg/day. Blood samples taken on 5 occasions from weaning to slaughter were assayed for progesterone. The weaning to estrous interval increased from 6.1 to 8.2 days when lactation length was reduced from 42 to 7 days. Ovulation rates, as determined by luteal count, were similar for the different periods of lactation. Numbers of viable embryos decreased significantly (p less than .05) as lactation length was reduced from 42 to 7 days. The survival of those embryos present decreased also (p less than .01). Embryo mortality increased from 17.3 to 40.4% when the lactation period was reduced from 42 to 7 days. Ovarian weights, uterine weights, and average embryo spacing were the same in all 3 groups. Plasma progesterone levels were low at weaning and remating, higher at 2 days postcoitum, and maximum at 10 days postcoitum. Between treatment groups, plasma progesterone levels were similar but varied markedly within treatment groups. Since ovulation rates were shown to be similar, this factor was eliminated. The interval from weaning to estrus was not considered important. Litter size was shown to be a major limiting factor. Embryo survival during the early period of gestation was shown to be the most important factor in limiting productivity.     

Control of the bovine estrous cycle with melengestrol acetate (MGA): a review

Expanded use of artificial insemination in the beef cattle industry depends on successful application of treatments designed to synchronize estrus. Regulation of estrous cycles is associated with control of the corpus luteum (CL), whose life span and secretory activity are subject to trophic and lytic mechanisms. The advantages of melengestrol acetate (MGA) in estrous synchronization incorporate ease of administration, lower cost relative to other estrous synchronization products, and potential for use to induce estrus in prepubertal heifers. Treatments first designed to synchronize estrous cycles of normally cycling heifers by feeding MGA were imposed daily for 14 to 18 d at levels of .5 to 1 mg. The minimal daily effective dose required to inhibit ovulation was .42 mg. Longer feeding periods of MGA were associated with low fertility at the first synchronized estrus, but at the second estrus, conception was normal. Low fertility at the synchronized estrus resulted in development of alternative treatment practices, which combined feeding of MGA with injections or implants of estradiol-17 beta, estradiol cypionate, luteinizing hormone, human chorionic gonadotropin, pregnant mare serum gonadotropin, or oxytocin. Estrus was synchronized after MGA and estradiol-17 beta or estradiol cypionate treatments, but fertility was low. Short-term feeding of MGA (5 to 7 d) combined with prostaglandin F2 alpha or its analogs (PGF) on the last day of MGA reduced fertility at the synchronized estrus. The reduced conception at first service occurred in animals that began treatment after d 12 of the estrous cycle. However, feeding MGA for 14 d and then injecting PGF 17 d later avoided problems with reduced conception. Fertility of animals after this treatment was similar to that of contemporaries synchronized with Syncro-Mate-B. However, the length of the treatment period creates a need for increased management and may extend management beyond practical limits. Further research is warranted to address problems associated with reduced fertility after short-term treatment with MGA.     

Studies on the pathogenesis of bovine ephemeral fever in sentinel cattle. I. Virology and serology

Twenty-two sentinel cattle were observed daily during an outbreak of ephemeral fever on a dairy farm in eastern Australia in the summer of 1981–192. Of the 22 cattle, 9 developed clinical ephemeral fever. None developed sub-clinical infection. The pattern of the epidemic was a single index case followed 10 days later by the main epidemic wave which lasted for 7 days. This wave stopped when there were still 14 uninfected susceptible animals remaining in the sentinel group, and when biting flies were very active. Ten isolations of bovine ephemeral fever virus were made in Aedes albopictus tissue cultures from the blood of 5 clinical cases. One hundred and twelve isolations of CSIRO Village virus and one each of Kimberley and Akabane viruses were also made from various members of the sentinel group. There was serological evidence that infections with Tibrogargan, Tinaroo and Aino viruses also occurred in 6 cattle in the observation period. The 13 cattle undergoing a sub-clinical viraemia with CSIRO Village virus, Tibrogargan, Kimberley, Akabane or Aino viruses at the time of the main outbreak, appeared to be temporarily protected against ephemeral fever. However, 9 of the 11 still remaining in the herd were susceptible in a subsequent outbreak of ephemeral fever 2 years later. Evidence is presented that subclinical infections with other arboviruses may limit an ephemeral fever epidemic by providing temporary protection by interference.     

Medical Management of Right Dorsal Colitis in 5 Horses: A Retrospective Study (1987–1993)

Right dorsal colitis in horses has been associated with administration of phenylbutazone. Although reports of right dorsal colitis in this species have described surgical treatment associated with a poor prognosis, we have had success treating this condition medically. This report describes 5 horses with right dorsal colitis confirmed during celiotomy that were initially managed medically. All horses had a history of intermittent abdominal pain; weight loss was noted in only 1 horse. The doses (2.0 to 4.6 mg/kg PO bid) and duration (5 to 30 days) of administration of phenylbutazone were not unusually high relative to those recommended (4.4 mg/kg PO bid). Hypoproteinemia and hypoalbuminemia were observed in all horses at the time of admission; packed cell volume was low in 4 horses, and hypocalcemia was also observed in 4 horses. Three of 5 horses (60%) appeared to respond to dietary management and discontinuation of administration of nonsteroidal anti-inflammatory drugs. Dietary management consisted of feeding pelleted feed, and restricting or eliminating roughage for a period of at least 3 months. Two horses developed strictures of the right dorsal colon. One horse that developed a colonic stricture, possibly because its owners did not comply with recommendations for management, was subsequently treated surgically. The remaining horse that developed a stricture of the right dorsal colon was euthanized. These data indicate that some horses with right dorsal colitis can be successfully managed with medical treatment.     

Pneumothorax in cats with a clinical diagnosis of feline asthma: 5 cases (1990–2000)

Objective: This paper characterizes the clinical findings in 5 cats with feline asthma complicated by concurrent pneumothorax. Design: Retrospective study. Medical records of cats with concurrent diagnoses of asthma and pneumothorax that were presented to the Veterinary Hospital of the University of Pennsylvania from 1990 to 2000 were reviewed. Results: Of 421 cases of feline asthma, 5 cats fulfilled the inclusion criteria (1.2%). All 5 had respiratory distress at presentation. One cat was panting, and the other 4 cats had respiratory rates of 28, 52, 58 and 120 breaths per minute (bpm), respectively (mean RR 65±39 bpm). Historical findings included untreated chronic cough (n=3), previously treated asthma (n=1), and no previous illness (n=1). Thoracocentesis was performed in 4/5 cats, and 3 of those cats required thoracostomy tubes. Four cats required immediate oxygen supplementation, and 1 of those cats required ventilation. All 5 cats had evidence of pneumothorax on initial radiographs. Follow‐up radiographs revealed partial or complete resolution of pneumothorax in 4 cats which were discharged alive with total hospitalization of 2–7 days, but were then lost to follow‐up. One cat was euthanized because it could not be weaned off mechanical ventilation, and necropsy confirmed end‐stage feline asthma and emphysema. Conclusion: Small airway obstruction can predispose asthma patients to increased alveolar pressure, emphysema, and spontaneous pneumothorax, which can lead to dyspnea in affected cats. The short‐term outcome in these cats was good despite the severity of dyspnea at presentation.