Effects of rumen stasis on sulfamethazine blood levels after oral administration in sheep.   总被引：1，自引：1，他引：0       下载免费PDF全文

C R Bischop  R E Janzen  D C Landals  B D Manns  D J McCartney  G A Morgan  V P Pawlyshyn  A J Schienbein  B W Scigliano    K L Taylor 《The Canadian veterinary journal. La revue veterinaire canadienne》1973,14(11):269-271

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Estrus synchronization and pregnancy rates in beef cattle given CIDR-B, prostaglandin and estradiol, or GnRH          下载免费PDF全文

Martínez MF  Kastelic JP  Adams GP  Janzen E  McCartney DH  Mapletoft RJ 《The Canadian veterinary journal. La revue veterinaire canadienne》2000,41(10):786-790

Two experiments were conducted to determine estrous response and pregnancy rate in beef cattle given a controlled internal drug release (CIDR-B) device plus prostaglandin F2 alpha (PGF) at CIDR-B removal, and estradiol or gonadotropin releasing hormone (GnRH). In Experiment I, crossbred beef heifers received a CIDR-B device and 1 mg estradiol benzoate (EB), plus 100 mg progesterone (E + P group; n = 41), 100 micrograms gonadotropin releasing hormone (GnRH group; n = 42), or no further treatment (Control group; n = 42), on Day 0. On Day 7, CIDR-B devices were removed and heifers were treated with PGF. Heifers in the E + P group were given 1 mg EB, 24 h after PGF, and then inseminated 30 h later. Heifers in the GnRH group were given 100 micrograms GnRH, 54 h after PGF, and concurrently inseminated. Control heifers were inseminated 12 h after onset of estrus. The estrous rate was lower (P < 0.01) in the GnRH group (55%) than in either the E + P (100%) or Control (83%) groups. The mean interval from CIDR-B removal to estrus was shorter (P < 0.01) and less variable (P < 0.01) in the E + P group than in the GnRH or Control groups. Pregnancy rate in the E + P group (76%) was higher (P < 0.01) than in the GnRH (48%) or Control (38%) groups. In Experiment II, 84 cows were treated similarly to the E + P group in Experiment I. Cows received 100 mg progesterone and either 1 mg EB or 5 mg estradiol-17 beta (E-17 beta) on Day 0 and either 1 mg of EB or 1 mg of E-17 beta on Day 8 (24 h after CIDR-B removal), in a 2 x 2 factorial design, and were inseminated 30 h later. There were no differences among groups for estrous rates or conception rates. The mean interval from CIDR-B removal to estrus was 44.2 h, s = 11.2. Conception rates were 67%, 62%, 52%, and 71% in Groups E-17 beta/E-17 beta, E-17 beta/EB, EB/E-17 beta, and EB/EB, respectively. In cattle given a CIDR-B device and estradiol plus progesterone, treatment with either EB or E-17 beta effectively synchronized estrus and resulted in acceptable conception rates to fixed-time artificial insemination.  相似文献   

Evidence of dehydration and electrolyte disturbances in cases of perennial ryegrass toxicosis in Australian sheep     

MDA Combs  D Rendell  KFM Reed  WJ Mace  JC Quinn 《Australian veterinary journal》2014,92(4):107-113

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Behavior of Hymenaea courbaril When Its Predispersal Seed Predator Is Absent     

Janzen DH 《Science (New York, N.Y.)》1975,189(4197):145-147

Members of lowland Costa Rican forest populations of Hymenaea courbaril (Leguminosae) have longer intervals between seed crops, a later age at first reproduction, larger seed crops, and more resin in the pod walls than do the H. courbaril native to Puerto Rico. The primary predispersal seed predators of H. courbaril in Costa Rica, Rhinochenus spp., are absent from Puerto Rico, and it is postulated that this is a major cause of the interpopulation differences.  相似文献   

Neotropical anachronisms: the fruits the gomphotheres ate     

Janzen DH  Martin PS 《Science (New York, N.Y.)》1982,215(4528):19-27

Frugivory by extinct horses, gomphotheres, ground sloths, and other Pleistocene megafauna offers a key to understanding certain plant reproductive traits in Central American lowland forests. When over 15 genera of Central American large herbivores became extinct roughly 10,000 years ago, seed dispersal and subsequent distributions of many plant species were altered. Introduction of horses and cattle may have in part restored the local ranges of such trees as jicaro (Crescentia alata) and guanacaste (Enterolobium cyclocarpum) that had large mammals as dispersal agents. Plant distributions in neotropical forest and grassland mixes that are moderately and patchily browsed by free-ranging livestock may be more like those before megafaunal extinction than were those present at the time of Spanish conquest.  相似文献   

L-Canaline Detoxification: A Seed Predator's Biochemical Mechanism     

Rosenthal GA  Dahlman DL  Janzen DH 《Science (New York, N.Y.)》1978,202(4367):528-529

The seeds of the Neotropical legume, Dioclea megacarpa, the sole food source for developing larvae of the bruchid beetle, Caryedes brasiliensis, contain about 13 percent L-canavanine (dry weight). Canavanine detoxification and utilization produces L-canaline, a potent neurotoxic and insecticidal amino acid. This seed predator has developed a unique biochemical mechanism for degrading canaline by reductive deamination to form homoserine and ammonia. In this way, canaline is detoxified; canavanine's stored nitrogen is more fully utilized and its carbon skeleton is conserved.  相似文献   

Euglossine bees as long-distance pollinators of tropical plants     

Janzen DH 《Science (New York, N.Y.)》1971,171(3967):203-205

Euglossine bees may return to a nest from as far away as 23 kilometers in a tropical rain forest. These bees apparently forage long distances and visit the same plants repeatedly along a feeding route. They probably promote outcrossing among tropical plants with low population density; therefore, they may permit the existence of plant species whose densities have been forced very low by such things as competition and predators on seeds and seedlings.  相似文献   

Agricultural soils as a sink to mitigate CO₂ emissions     

K. Paustian  O. Andrén  H. H. Janzen  R. Lal  P. Smith  G. Tian  H. Tiessen  M. Van  Noordwijk  P. L. Woomer 《Soil Use and Management》1997,13(S4):230-244

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Depletion of intramuscularly and subcutaneously injected procaine penicillin G from tissues and plasma of yearling beef steers.   总被引：2，自引：1，他引：1       下载免费PDF全文

G O Korsrud  J O Boison  M G Papich  W D Yates  J D MacNeil  E D Janzen  R D Cohen  D A Landry  G Lambert  M S Yong  et al. 《Canadian journal of veterinary research》1993,57(4):223-230

Withdrawal periods required when doses of 24,000 IU and 66,000 IU of procaine penicillin G/kg body weight were administered to yearling beef steers by intramuscular injection daily for five consecutive days were investigated. These dosages are in excess of product label recommendations, but are in the range of procaine penicillin G dosages that have been administered for the treatment of some feedlot bacterial diseases. The approved dose in Canada is 7,500 IU/kg body weight intramuscularly, once daily, with a withdrawal period of five days. Based on the tissue residue data from this study, the appropriate withdrawal period is ten days for the 24,000 IU/kg body weight dose and 21 days for the 66,000 IU/kg body weight dose when administered intramuscularly to yearling beef steers. In a related study, 18 yearling beef steers received 66,000 IU of procaine penicillin G/kg body weight administered by subcutaneous injection, an extra-label treatment in terms of both dose and route of administration, typical of current practice in some circumstances. Deposits of the drug were visible at subcutaneous injection sites up to ten days after injection, with more inflammation and hemorrhage observed than for intramuscular injections of the same dose. These results suggest that procaine penicillin G should not be administered subcutaneously at high doses; and therefore a withdrawal period was not established for subcutaneous injection.  相似文献   

Pathology of experimentally-induced, acute toxoplasmosis in macropods   总被引：1，自引：0，他引：1  

GL REDDACLIFF  WJ HARTLEY  JP DUBEY  DW COOPER 《Australian veterinary journal》1993,70(1):4-6

SUMMARY Thirteen Tammar wallabies (Macropus eugenii) were dosed orally with 500, 1000 or 10 000 oocysts of Toxoplasma gondii, as part of a vaccination trial. Eleven animals died of acute toxoplasmosis 9 to 15 days after challenge. The lesions were similar in all animals, consisting of foci of necrosis and inflammation in the intestines, lymphoid tissue, adrenal cortex, heart, skeletal muscle and brain, and severe generalised pulmonary congestion and oedema. Free and intracellular tachyzoites of Toxoplasma were associated with the lesions. The remaining 2 animals had shown no signs of disease when euthanased four months after challenge. Small, focal, non-suppurative inflammatory lesions were seen in brain, heart and skeletal muscle of these animals and chronic Toxoplasma infection was confirmed by mouse inoculation.  相似文献