Monitoring distances travelled by horses using GPS tracking collars     

BA Hampson  JM Morton  PC Mills  MG Trotter  DW Lamb  CC Pollitt 《Australian veterinary journal》2010,88(5):176-181

Objective The aims of this work were to (1) develop a low-cost equine movement tracking collar based on readily available components, (2) conduct preliminary studies assessing the effects of both paddock size and internal fence design on the movements of domestic horses, with and without foals at foot, and (3) describe distances moved by mares and their foals. Additional monitoring of free-ranging feral horses was conducted to allow preliminary comparisons with the movement of confined domestic horses. Procedures A lightweight global positioning system (GPS) data logger modified from a personal/vehicle tracker and mounted on a collar was used to monitor the movement of domestic horses in a range of paddock sizes and internal fence designs for 6.5-day periods. Results In the paddocks used (0.8–16 ha), groups of domestic horses exhibited a logarithmic response in mean daily distance travelled as a function of increasing paddock size, tending asymptotically towards approximately 7.5 km/day. The distance moved by newborn foals was similar to their dams, with total distance travelled also dependent on paddock size. Without altering available paddock area, paddock design, with the exception of a spiral design, did not significantly affect mean daily distance travelled. Feral horses (17.9 km/day) travelled substantially greater mean daily distances than domestic horses (7.2 km/day in 16-ha paddock), even when allowing for larger paddock size. Conclusions Horses kept in stables or small yards and paddocks are quite sedentary in comparison with their feral relatives. For a given paddock area, most designs did not significantly affect mean daily distance travelled.  相似文献   

Inoculation of pines with mycorrhizal fungi in natural soils—III: Effect of soil fumigation on rate of infection and response to inoculum density     

R.J. Lamb  B.N. Richards 《Soil biology & biochemistry》1978,10(4):273-276

Pinus radiata seedlings were inoculated with basidiospores of Rhizopogon roseolas and Suillus granulatus, and with chlamylospores of two unidentified but highly effective mycorrhizal fungi in undisturbed cores of natural soil fumigated with methyl bromide. Fumigation stimulated mycorrhizal infection rate and enhanced the response of seedlings to increasing concentrations of both inoculum types, but the effect of chlamydospore inoculum was more favoured by fumigation than that of basidio-spores. Chlamydospore inocula appear more sensitive to competitive and antagonistic soil microorganisms than basidiospores. Soil fumigation appears a necessary adjunct to the use of chlamydospores as inoculants in nurseries and is discussed in relation to nursery culture of pines.  相似文献   

CHANGES IN ULTRASONOGRAPHIC APPEARANCE OF ADRENAL GLANDS IN DOGS WITH PITUITARY-DEPENDENT HYPERADRENOCORTICISM TREATED WITH TRILOSTANE     

Panagiotis  Mantis  DVM  Christopher R.  Lamb  MA  VetMB  Angela L.  Witt  DVM  Reto  Neiger  Dr Med Vet  PhD 《Veterinary radiology & ultrasound》2003,44(6):682-685

Trilostane, a 3beta-hydroxysteroid dehydrogenase inhibitor, has been used successfully over the last few years for the treatment of canine pituitary-dependent hyperadrenocorticism. In a prospective study of 19 dogs with pituitary-dependent hyperadrenocorticism, the adrenal glands were measured before and at least 6 months after initiation of trilostane therapy. Right adrenal gland length and caudal pole thickness and left adrenal gland caudal pole thickness increased significantly (p < or = 0.05); there was no significant change in left adrenal gland length. Enlargement of adrenal glands during trilostane therapy may occur as a result of suppression of the negative feedback mechanism affecting cortisol production.  相似文献   

Influence of body condition and bovine somatotropin on estrous behavior, reproductive performance, and concentrations of serum somatotropin and plasma fatty acids in postpartum Brahman-influenced cows     

Flores R  Looper ML  Rorie RW  Lamb MA  Reiter ST  Hallford DM  Kreider DL  Rosenkrans CF 《Journal of animal science》2007,85(5):1318-1329

Ninety-nine multiparous Brahman-influenced (1/4 to 3/8 Brahman) cows were managed to achieve low (BCS = 4.3 +/- 0.1; n = 50) or moderate (BCS = 6.1 +/- 0.1; n = 49) body condition (BC) to determine the influence of bovine somatotropin (bST) on estrous characteristics, reproductive performance, and concentrations of serum GH and plasma NEFA. Beginning 32 d postpartum, cows within each BC were assigned randomly to treatment with or without bST. Non-bST-treated cows received no treatment, and treated cows were administered bST (Posilac, 500 mg s.c.) on d -35, -21, and -7 before initiation of the breeding season. On d -7, all cows received an intravaginal, controlled internal drug-releasing (CIDR) device. On d 0 (initiation of the 70-d breeding season), the CIDR were removed and cows received prostaglandin F2alpha (PGF2alpha). Blood samples were collected from the median caudal vein of the cows at each bST treatment and at d -28 and 0. Estrous behavior was monitored by radiotelemetry during the first 30 d of the breeding season. Growth hormone was increased (P < 0.05) in low and moderate BC cows treated with bST. The percentage of cows detected in estrus during the first 30 d of the breeding season was decreased (P = 0.05) for low BC (64%) compared with moderate BC (82%) cows. The interval to first estrus tended (P = 0.07) to be shorter in low BC-bST-treated cows (3.7 +/- 1.9 d) than in moderate BC-bST-treated cows (9.6 +/- 1.8 d). During the first 30 d of the breeding season, cows in low BC had a decreased (P = 0.02) number of mounts received and increased (P = 0.001) quiescence between mounts compared with cows in moderate BC. The number of mounts received was reduced (P = 0.04) in bST-treated cows. More (P = 0.02) cows treated with bST became pregnant during the first 3 d of the breeding season compared with non-bST-treated cows. The cumulative first-service conception rate tended (P = 0.07) to be greater for bST-low BC cows than non-bST-treated cows in low or moderate BC. On d 0, NEFA were greater (P < 0.05) in bST-treated vs. non-bST-treated cows. Low BC and bST reduced the intensity of behavioral estrus in postpartum Brahman-influenced cows. However, bST increased the first-service conception rate during the first 30 d of breeding and pregnancy rates during the first 3 d of breeding in postpartum Brahman-influenced cows.  相似文献   

Evaluating the non-consumptive, positive effects of a predator in the persistence of an endangered species     

Lauren M. Pintor  Daniel A. Soluk 《Biological conservation》2006,130(4):584-591

Failure to consider both the consumptive and non-consumptive effects of predators on prey can lead to erroneous conclusions about the net effect of the relationship. The predatory devil crayfish, Cambarus diogenes Girard functions as an ecosystem engineer constructing extensive burrow systems through aquatic habitats. Despite crayfish posing a serious predation threat, preliminary data indicate that the federally endangered Hines Emerald dragonfly larvae, Somatochlora hineana Williamson regularly inhabit crayfish burrows. During late summer, S. hineana larval habitat dries up; leaving crayfish burrows as some of the only wetted habitats. Thus, C. diogenes can affect S. hineana through both direct, negative and indirect positive effects. We examined the positive role of crayfish burrows as drought refuges, and the threat of predation by C. diogenes on S. hineana larvae. Monthly field sampling indicated that S. hineana use open channel areas in spring and early summer moving into burrow systems in mid summer when channel areas normally dry. Laboratory experiments and field observations confirmed that crayfish prey on S. hineana larvae. Adult crayfish were a larger predation threat than juvenile crayfish. Despite their negative predatory impact, removal of crayfish from burrows in the field did not enhance densities of S. hineana larvae. Although S. hineana may face the threat of predation in burrows, they face a greater risk of desiccation if they remain in the open channel. These results lead to the counterintuitive conclusion that the maintenance of a predator is important for conserving an endangered prey species.  相似文献   

Book reviews     

T. Viraraghavan  V. A. Kovda  A. Yu. Kudeyarova  Brian Lamb  Elmer Robinson  Y. Okatan  M. Bara  Emilio Astolfi  Clarence G. Golueke  Yener Okatan  G. F. Humphrey 《Water, air, and soil pollution》1983,20(3):347-359

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Interactions between 14C-labelled atrazine and the soil microbial biomass in relation to herbicide degradation     

G. Ghani  D. A. Wardle  A. Rahman  D. R. Lauren 《Biology and Fertility of Soils》1996,21(1-2):17-22

A laboratory incubation experiment was set up to determine the effects of atrazine herbicide on the size and activity of the soil microbial biomass. This experiment was of a factorial design (0, 5, and 50 g g^–1 soil of non-labelled atrazine and 6.6×10³ Bq g^–1 soil of ¹⁴C-labelled atrazine) x (0, 20, and 100 g g^–1 soil of urea-N) x (pasture or arable soil with a previous history of atrazine application). Microbial biomass, measured by substrate-induced respiration and the fumigation-incubation method, basal respiration, incorporation of ¹⁴C into the microbial biomass, degradation of atrazine, and ¹⁴C remaining in soil were monitored over 81 days. The amount of microbial biomass was unaffected by atrazine although atrazine caused a significant enhancement of CO₂ release in the non-fumigated controls. Generally, the amounts of atrazine incorporated into the microbial biomass were negligible, indicating that microbial incorporation of C from atrazine is not an important mechanism of herbicide breakdown. Depending on the type of soil and the rate of atrazine application, 18–65% of atrazine was degraded by the end of the experiment. Although the pasture soil had twice the amount of microbial biomass as the arable soil, and the addition of urea approximately doubled the microbial biomass, this did not significantly enhance the degradation of atrazine. This suggests that degradation of atrazine is largely independent of the size of the microbial biomass and suggests that other factors (e.g., solubility, chemical hydrolysis) regulate atrazine breakdown. A separate experiment conducted to determine total amounts of ¹⁴C-labelled atrazine converted into CO₂ by pasture and arable soils showed that less than 25% of the added ¹⁴C-labelled atrazine was oxidised to ¹⁴CO₂ during a 15-week period. The rate of degradation was significantly greater in the arable soil at 24%, compared to 18% in the pasture soil. This indicates that soil microbes with previous exposure to atrazine can degrade the applied atrazine at a faster rate.  相似文献   

Acidic mammalian chitinase in asthmatic Th2 inflammation and IL-13 pathway activation     

Zhu Z  Zheng T  Homer RJ  Kim YK  Chen NY  Cohn L  Hamid Q  Elias JA 《Science (New York, N.Y.)》2004,304(5677):1678-1682

Chitin is a surface component of parasites and insects, and chitinases are induced in lower life forms during infections with these agents. Although chitin itself does not exist in humans, chitinases are present in the human genome. We show here that acidic mammalian chitinase (AMCase) is induced via a T helper-2 (Th2)-specific, interleukin-13 (IL-13)-mediated pathway in epithelial cells and macrophages in an aeroallergen asthma model and expressed in exaggerated quantities in human asthma. AMCase neutralization ameliorated Th2 inflammation and airway hyperresponsiveness, in part by inhibiting IL-13 pathway activation and chemokine induction. AMCase may thus be an important mediator of IL-13-induced responses in Th2-dominated disorders such as asthma.  相似文献   

THE CONSTITUTION OF THE EARTH     

Lamb H 《Science (New York, N.Y.)》1925,62(1602):229-236

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Mentoring. Linking student interests to science curricula     

Denofrio LA  Russell B  Lopatto D  Lu Y 《Science (New York, N.Y.)》2007,318(5858):1872-1873

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