Morphological comparison of wild,farmed and hybrid specimens of two South American silversides,Odontesthes bonariensis and Odontesthes hatcheri

In this study, body shape of hybrid and presumptive introgressed South American silversides was studied. Body shape of O. bonariensis and O. hatcheri from wild populations and farmed stocks was compared to provide basic information on the effects of fish farming on morphometric parameters. Subsequently, wild presumptive introgressed individuals and artificially hybridized farmed individuals were morphologically analysed to assess the effects of hybridization on the same parameters. Most farmed purebred individuals were shorter and higher than their wild counterparts, which is probably due to the favourable growth conditions compared to the wild habitat. However, the results evidenced that purebred individuals were more slender than both hybrid (farmed) fish and introgressed (wild) fish. Further studies on the growth performance of hybrid Odontesthes will be required in order to assess whether the combination of hybridization and sterilization could produce, under farming conditions, growth performances which satisfy the requirements of aquaculture.     

Biodiversity conservation in human-modified landscapes of Mesoamerica: Past, present and future

Mesoamerica provides a unique context for biodiversity conservation in managed landscapes because of its geography, history of human intervention, and present conservation and development initiatives. The long and narrow form of the Mesoamerican landmass, and its division by a central mountain range, has served as both a bridge and a barrier. Conservation efforts in Mesoamerica are unique for the emphasis they place on regional connectivity through the Mesoamerican Biological Corridor and on biodiversity conservation in managed landscapes. The emphasis on conservation in agricultural systems has fostered innovations in payment for ecosystem services, and provides novel insights on the functional role that biodiversity plays in the provisioning of ecosystem services. The increasing rate of economic development in the region and the advent of new payment for ecosystem service schemes have provided new opportunities for forest regeneration and restoration. However, the small scale of private landholdings and the diversity of land uses featured in the region, while contributing to biodiversity conservation due to their structural and floristic complexity, present challenges for biodiversity monitoring and management.     

Skull size and shape variation in Psammomys spp. (Rodentia,Gerbillinae) from Tunisia,with emphasis on the impact of allometric variation on species recognition

In Tunisia both Psammomys obesus and P. vexillaris are found. These taxa have been the subject of taxonomic controversy for some time, due to variability in the classical morphological characters used for taxonomic recognition. In this study we investigated skull size and shape variation in the genus Psammomys by using geometric morphometrics to evaluate the extent of intra- and interspecific shape variation and explicitly tested for the impact of allometric shape variation on species discrimination. Eleven populations of the two species from 10 localities in Tunisia were studied. Statistical analyses of size and shape showed large size variation within P. obesus, but no shape differences were revealed among populations of this species. Interspecific analysis revealed that P. vexillaris had the smallest skull. Principal component analysis and Procrustes distances showed good discrimination between the two species after removal of the allometric component of shape variation. The results obtained show that allometric-related shape variation could mask discrimination between the two Psammomys species. This finding might explain the uncertainty in classification of these species in the past. The interspecific allometric-free phenotypic differences observed may be associated with adaptive processes linked to the different environmental and trophic preferences of the two species.     

Osteomalacia as a result of phosphorus deficiency in beef cattle grazing subtropical native pastures in Uruguay

We investigated 2 outbreaks of osteomalacia as a result of phosphorus (P) deficiency in herds of lactating beef cows grazing subtropical native pastures in Uruguay. Cows exhibited pica, difficulty to stand and walk, rib fractures, and body weight loss even with adequate forage availability. Osteopenia and severe osteomalacia were observed on gross and histologic examination. The concentrations of bicarbonate-extractable P in soil (4.0, 4.1 mg P/kg), total P in pasture (0.9, 1.1 g P/kg), inorganic P in serum (1.0, 0.71 mmol P/L), and P in bone (73 mg P/mL) were all low. Although injectable and mineral salt supplements provided additional P in both outbreaks, these supplementary amounts were insufficient to prevent P deficiency. The P ingested by the cows from the pasture and supplements would have provided 20–55% of their daily P requirements of ~21 g P/d. Osteomalacia occurred in cattle at the 2 ranches as a result of severe P deficiency in the soil and forage, and inadequate P supplementation. Following diagnosis, control of P deficiency in beef cattle requires estimation of the amount of pasture P ingested and provision of sufficient additional supplementary P to meet the animals’ requirements.     

Predatory aggression in a German shepherd dog

This article presents a clinical case of predatory aggression that represents a problem for public health. The patient was a 2-year-old male German shepherd referred to the behavior clinic at the School of Veterinary Medicine owing to its aggressive behavior toward people and other dogs. The dog tended to form a pack with the other dogs of the household and killed neighborhood dogs, cats, hens, and rabbits. The presumptive diagnosis was “predatory aggression” associated with “territorial and protective aggression.” The risk analysis determined that the dog should be euthanized. Nevertheless, the owner refused, and hence behavior modification and drug therapy were recommended. A year later, the dog killed again (another dog), indicating that despite the drug and behavioral treatment, it is likely that its predatory aggression will never be resolved.     

Seasonal Changes in Forage Nutrients and Mineral Contents in Water Resources,Forage and Yak Blood

This paper reports results of a study conducted to investigate the concentrations of seven mineral elements in yak blood, forage and water resources around the Qinghai Lake in Qinghai Province in different seasons. Meanwhile, the nutritional compositions of the forage were also surveyed. The results suggest that the mineral elements and the forage nutrients change in a seasonal pattern. In yak blood,the sodium(Na)concentration varies from 0.291 to 0.034 mg/mL,and this is lower than the normal value. In the forage,the ratio calcium(Ca)to phosphorus(P)is 4.06～7.47:1 and potassium(K)to Na 30～27:1. These results indicate that the nutrition of the yak in the area is deficient in Na but high in K. For the withered forage sampled in February,the protein content is only 31.14% of the total protein in the forage growing at puerile stage in June. The severe loss of protein by 68. 9% and decrease of effective nutrients in the wintered forage are considered to be the reasons resulting in the poor condition of yak in winter and spring seasons.     

Effect of feed intake level and dietary protein content on the body temperature of pigs housed under thermo neutral conditions

Feed intake and diet composition appear to affect the body temperature of pigs. Two trials were conducted to analyse the effect of feed intake level and dietary protein content on the intestinal temperature (IT) of pigs housed under thermo neutral conditions. Ten pigs (64.1 ± 1.3 kg initial body weight) fitted with an ileal cannula were used. A thermometer set to register the IT at 5‐min intervals was implanted into the ileum through the cannula. In both trials, the ambient temperature ranged from 19.1 to 21.6°C and the pigs were fed at 07:00 and 19:00 hr (same amount each time). In trial 1, the pigs were fed daily 1.2 or 1.8 kg of a wheat–soybean meal diet. The IT followed a similar pattern along a 24‐hr period regardless the feed intake level. The IT rapidly increased up to 0.61 and 0.74°C after the morning meal and up to 0.53 and 0.47°C after the evening meal in pigs fed 1.2 and 1.8 kg/d respectively. The postprandial IT was higher in pigs fed 1.8 kg after each meal (p < .05). In trial 2, pigs were fed daily 1.8 kg of a low (11%) or a high (22%) crude protein diet. The IT followed a similar pattern along the 24‐hr period regardless the dietary protein level. The postprandial IT did not differ between pigs fed the low protein or the high protein (p > .10). The IT rapidly increased up to 0.66 and 0.62°C after the morning meal in pigs fed the high‐ and low‐protein diet (p < .05), but there was no change after the evening meal (p > .10). In conclusion, the feed intake level affected the IT of pigs housed under TN conditions, but the dietary protein content had no effect.     

Effect of aluminum on callose synthesis in root tips of tea (Camellia sinensis L.) plants

Aluminum (Al) toxicity is a major factor limiting yield production on acid soils (Foy 1983). The initial symptom of Al toxicity in many plants is manifested by the inhibition of root elongation (Ownby and Popham 1990; Llugany et al. 1994; Sasaki et al. 1994; Horst et al. 1997), which occurs during a very short period of time after exposure to Al (Llugany et al. 1994; Staß and Horst 1995). In a large number of recent reports, it was shown that the root apex plays a major role in the Al-sensitivity and response mechanisms (Zhang et al. 1994; Sasaki et al. 1997; Sivaguru and Horst 1998). However, it is interesting to note that stimulatory effects of Al on the growth of plants have also been reported in some studies (Chenery 1955; Konishi et al. 1985; Huang and Bachelard 1993; Osaki et al. 1997). In tea plant (Camellia sinensis L.) a stimulatory effect of Al on the growth was also demonstrated in some experiments, using intact plant (Chenery 1955; Konishi et al. 1985), cultured roots (Tsuji et al. 1994), and pollen tubes (Yokota et al. 1997). The growth of tea roots was typically more stimulated than that of shoots by Al (Konishi et al. 1985). It was assumed that Al effects might be due to the amelioration of phosphorus absorption (Konishi et al. 1985), secretion of malic acid from roots to dissolve aluminum phosphate in the rhizosphere (Jayman and Sivasubramaniam 1975), stimulation of growth of microorganisms on the root surface (Konishi 1990) or replacement of some functions of boron (Konishi 1992; Yokota et al. 1997). However, the stimulatory effects of Al on tea plant growth have not yet been el ucidated.

The formation of callose (1,3-β-glucan) has been reported as a common plant response to a variety of stresses, as well as mechanical, biophysical, chemical, and biological injury (Jaffe and Leopold 1984; Zhang et al. 1994). Increased synthesis of callose has been observed upon exposure to excess amounts of some elements, such as boron (McNairn and Currier 1965), cobalt, nickel, zinc (Peterson and Rauser 1979), and manganese (Wissemeier and Horst} 1987, 1992). Callose synthesis was also induced by Al in the roots of Triticum aestivum (Zhang et al. 1994) and Zea mays (Horst et al. 1997; Sivaguru and Horst 1998), suspension-cultured cells of Glycine max (Staß and Horst 1995), and protoplasts of Avena sativa (Schaeffer and Walton 1990) and Zea mays (Wagatsuma et al. 1995). Induction of callose synthesis in roots seems to be a very rapid physiological indicator of Al-induced injury or genotypical differences in Al sensitivity (Wissemeier and Horst 1992; Zhang et al. 1994; Horst et al. 1997). Nevertheless, Al-induced callose synthesis in tea plant, whose growth is stimulated by suitable Al concentrations, has not been described yet. Therefore, to elucidate the physiological basic effects of Al on tea plant, callose synthesis affected by Al in the root tips of intact plants was analyzed in the present study.     

An evaluation of furrows for managing soil and water loss from a shallow Alfisol under simulated rainfall

Furrows are widely used in rainfed areas of semi-arid India for soil and water conservation. The orientation of furrows, either down or across slope, and their spacing influence the effectiveness of furrows as soil and water conservation measures. We evaluated treatments with furrows aligned down and across 3% sloping land at spacings of 90, 60 and 30 cm under simulated rainfall intensities of 80 and 100 mm/h on a shallow Alfisol. A bare plot without any furrows was considered as a control. A large (24 m × 3 m) rainfall simulator developed at the Central Research Institute for Dryland Agriculture (CRIDA), Hyderabad, was used for this controlled study. Run-off was measured by a calibrated tipping bucket run-off recorder. The effects of the treatments on peak flow rate (L/s), sediment loss with run-off water (kg/ha/mm), peak sediment concentration (g/L), run-off (per cent rainfall) and time to peak (min) were investigated. When compared with the control (no furrows), across slope furrowing with 60- and 30-cm spacing reduced sediment yields by 19.9 and 21.3 kg/ha/mm of run-off, respectively, under a rainfall intensity of 80 mm/h and 24 and 25.3 kg/ha/mm of run-off, respectively, under a rainfall intensity of 100 mm/h. For the control, sediment loss was 50.72 kg/ha/mm run-off and 56.68 kg/ha/mm run-off for rainfall intensities of 80 and 100 mm/h, respectively. Similar trends were recorded from observations of peak flow, time to peak and peak sediment concentration. Run-off hydrographs demonstrated the conservation value of across slope furrowing by delaying run-off initiation, reducing run-off and slowly releasing the run-off after the cessation of rainfall. The results show that furrow orientation has major effects on reducing run-off, whereas furrow spacing has insignificant effects.