Evaluation of Sperm-Activating Solutions in Atlantic Salmon Salmo salar Fertilization Tests

The use of saline solutions was tested to determine their efficacy as replacements for ovarian fluid as sperm activators and to eliminate variability encountered with the use of Ovarian fluid. We tested fertilization rate of semen from eight males on Atlantic salmon Salmo salar eggs after five sperm-activating solutions and a non-activating saline were substituted for ovarian fluid. We used solutions shown acceptable for use with other salmonid species. The six solutions tested were a non sperm-activating phosphate-buffered saline (PBS, 7.2 g/L NaCl, 1.48 g/L Na₂HPO₄, 0.43 g/L K H₂PO₄), a Tris buffer (6.99 g/L NaCl, 3.63 g/L Tris and 2.42 g/L glycine), a Borax buffer (12.2 g boric acid/L in solution 1, 76 g disodium tetraborate/L combined 100:118, then 1 L combined with 3.7 L water and 18 g NaCl), and three solutions of 9.25 g/L (125 mM) NaCl buffered to pH 6.0, 7.5, and 8.9. The latter five solutions activated sperm immediately on contact, while PBS required additional water to activate sperm. The PBS solution was the least effective (mean percent eyed eggs 37.6%) for egg fertilization. The mean percent eyed eggs for the other five saline solutions (range 78% to 86%) were not significantly different. Sperm from one male provided significantly lower egg fertilization (39.6%) when compared with the other seven males (67.2–87.4% egg fertilization). Percent egg fertilization was not related to number of live sperm cells per egg. Our results show that osmotically-balanced sperm-activation solutions, even those with a pH range from 6.0 to 8.9 provide adequate media for fertilization of Atlantic salmon eggs. Fertilization in a deactivation saline and water reactivation of sperm resulted in low egg fertilization.     

Factors affecting the hatchability of eggs from broiler breeders

1. Four experiments were carried out on eggs from broiler breeding flocks between 26 and 60 weeks of age. The effects of storage and incubation conditions on hatchability were tested.

2. Collecting eggs hourly rather than five hours after lay slightly reduced hatchability (P<0.10). Pre‐storage fumigation of almost un‐contaminated eggs had no effect on hatchability even after storage for 8 d. Storing eggs in unsealed polythene bags did not affect hatchability of eggs stored for 5 or 8 d.

3. Eggs stored for 2 d hatched better when held at 18 °C than at 15 °C (P<0.05). Eggs stored for 8 d at 15 °C hatched better than eggs stored for 8 d at 18 °C (P< 0.01). Best hatchability was in eggs stored in unsealed polythene bags at a room temperature of 15 °C. When older eggs were allowed 30 to 40 min more in the setter for each day of storage, the decline in hatchability was 0.5 to 0.6 percentage units per day in storage as compared with a decline of 1.2 percentage units per day when eggs of different storage times, up to 8 d, were set simultaneously.

4. Those eggs which showed a weight loss during incubation of near average for their relative humidity (RH) treatment tended to hatch better than others except under conditions of very low RH (0.36), when best hatchability was associated with lower than average weight loss.

5. In eggs from a young flock (28 to 44 weeks of age) hatchability of fertile eggs was depressed by 1 percentage unit with an increase in RH of 0.17, and by 1 percentage unit with each decrease of 0.06 in RH from a control RH of 0.53. In eggs from the same flock between 48 and 60 weeks of age hatchability was depressed by 1 percentage unit with each 0.037 increase in RH from 0.44 to 0.70.

6. Eggs from a young flock (34–49 weeks) hatched significantly better when maintained at 0.82 rather than at 0.66 (P<0.05) or 0.95 (P<0.10) RH during the hatching period from 19 to 21 d of incubation. Eggs from an older flock (51–61 weeks) hatched better at 0.82 and at 0.‐92 than at 0.72 RH during the same period, but the differences were not significant.     

Characterizing historical and modern fire regimes in Michigan (USA): A landscape ecosystem approach

We studied the relationships of landscape ecosystems to historical and contemporary fire regimes across 4.3 million hectares in northern lower Michigan (USA). Changes in fire regimes were documented by comparing historical fire rotations in different landscape ecosystems to those occurring between 1985 and 2000. Previously published data and a synthesis of the literature were used to identify six forest-replacement fire regime categories with fire rotations ranging from very short (<100 years) to very long (>1,000 years). We derived spatially-explicit estimates of the susceptibility of landscape ecosystems to fire disturbance using Landtype Association maps as initial units of investigation. Each Landtype Association polygon was assigned to a fire regime category based on associations of ecological factors known to influence fire regimes. Spatial statistics were used to interpolate fire points recorded by the General Land Office. Historical fire rotations were determined by calculating the area burned for each category of fire regime and dividing this area by fifteen (years) to estimate area burned per annum. Modern fire rotations were estimated using data on fire location and size obtained from federal and state agencies. Landtype Associations networked into fire regime categories exhibited differences in both historical and modern fire rotations. Historical rotations varied by 23-fold across all fire rotation categories, and modern forest fire rotations by 13-fold. Modern fire rotations were an order of magnitude longer than historical rotations. The magnitude of these changes has important implications for forest health and understanding of ecological processes in most of the fire rotation categories that we identified.This revised version was published online in May 2005 with corrections to the Cover Date.     

Equine ocular anatomy and ophthalmic examination.

This article is intended to provide the practitioner with a succinct but complete source regarding equine orbital and ocular anatomy,instrumentation available for ophthalmic examination, a methodical examination technique, sedation and regional nerve blocks, and diagnostic procedures involving the eye. Such knowledge of orbital and ocular anatomy is essential to allow recognition of normal,normal variations, or an abnormality of the equine eye and orbit.     

Diagnosis and treatment of a cerebral infarct in a chimpanzee (Pan troglodytes).

A 29-yr-old chimpanzee (Pan troglodytes) presented after an acute onset of right facial and forearm paresis that progressed to paralysis within 24 hr, with subsequent development of right leg paresis. Magnetic resonance imaging (MRI) of the head revealed an abnormal region of increased signal intensity in the left frontal, parietal, and temporal cerebral hemispheres, corresponding to the vascular territory of the middle cerebral artery, with resultant compression of the left lateral ventricle. The findings were consistent with a cerebral infarct (stroke). MRI is the most sensitive test for early detection of cerebral changes due to ischemia and was essential in obtaining a diagnosis in this case. The chimpanzee responded well to treatment with long-term anticoagulant aspirin and a short, tapered course of prednisone and regained full gross motor function.     

Suspect osteogenesis imperfecta in a male kitten

A 4.5-month-old, male domestic shorthair was presented with bilateral femoral fractures after falling from a low height. Radiographs revealed reduced radio-opacity and thin cortices of all long bones. A presumptive diagnosis of osteodystrophy, secondary to osteogenesis imperfecta, was made on postmortem examination.     

Onchocerca sp. in an imported Zangersheide gelding causing suspensory ligament desmitis

A 5-year-old imported Zangersheide gelding was evaluated for SC swellings over both forelimbs and lameness localized to the distal metacarpus. Ultrasound examination of the SC masses was compatible with verminous granulomas. Linear hyperechoic foci were present within the suspensory ligament branches of both forelimbs, suggestive of ligamentous parasitic infiltrates. A diagnosis of onchocerciasis was confirmed on biopsy of a SC mass. The gelding was treated with ivermectin and a tapering course of PO dexamethasone but was eventually euthanized. Necropsy confirmed the presence of SC eosinophilic granulomas and degenerative suspensory ligament desmitis, both with intralesional nematodes. Given the location and appearance of the nematode, a diagnosis of Onchocerca sp., most likely O. reticulata, was made. Onchocerciasis should be included as a differential diagnosis for multifocal suspensory ligament desmitis with these sonographic characteristics when paired with SC masses in imported European Warmbloods.     

Exposure of four Filipino farmers to parathion-methyl while spraying string beans

Filipino farmers resist wearing protective garments while spraying, preferring to wear long-sleeved cotton polyester shirts and short or long trousers. The exposure of farmers while wearing this attire and spraying was assessed to determine what degree of protection it afforded farmers under tropical conditions. Absorbent pads were placed on the outer and inner wear on various body parts. Applicators sprayed parathion-methyl on fruiting string beans at the recommended rate and residues were analyzed by gas chromatography. Each farmer had a characteristic spraying pattern which resulted in peculiar residue levels in some body parts. Inner exposure did not exceed the tolerable dermal exposure level during warm days while using proper spraying techniques. The use of long-sleeved cotton polyester shirt and thick polyester trousers provides, to a certain degree, protection for farmers during warm days. A change of clothing would be a more acceptable measure for farmers than wearing uncomfortable and impractical protective garments. The following spraying techniques reduced farmer exposure: fully outstretched arm, minimal body twisting and smooth hand movements. The use of thick polyester long trousers, gloves or a suitable substitute and the removal of weeds within the crop area also reduce farmer exposure to insecticides. Re-designing the bottle to include a plastic lip, in order to avoid spillage, is also recommended to reduce exposure during the critical mixing stage. Laundering the shirt immediately after use removes a significant amount of residues (96–97%) and contributes towards the protection of farm workers. These recommendations should provide useful data for incorporation in farmer-training programes on the proper use of pesticides.