Nutritional reference values for Opuntia ficus‐indica determined by means of the boundary‐line approach

Optimum concentrations and/or sufficiency ranges of nutrients are useful for a correct diagnosis and improvement of nutrient status of cultivated plants. To develop boundary‐line approach (BLA) standards for Opuntia ficus‐indica L., a database of N, P, K, Ca, and Mg concentrations in 1‐year‐old cladodes and cladodes fresh‐matter yield was used. The BLA optimum concentrations (associated with estimated maximum yield) for O. ficus‐indica were: N = 13.1 g kg^–1, P = 3.2 g kg^–1, K = 44.4 g kg^–1, Ca = 38.1 g kg^–1, and Mg = 17.3 g kg^–1. The BLA sufficiency ranges at 95% yield were 8.4–20.3 g kg^–1 for N, 2.4–4.2 g kg^–1 for P, 38.2–50.8 g kg^–1 K, 31.8–45.2 g kg^–1 for Ca, and 14.3–20.9 g kg^–1 for Mg. The BLA standards are comparable to those obtained in a previous study using compositional‐nutrient‐diagnosis (CND) approach.     

Influence of topographic and edaphic factors on vulnerability to soil degradation due to cattle grazing in humid tropical mountains in northern Honduras

Low altitude humid tropical mountains in Central America have experienced a process of livestock expansion during recent decades. However, the use of sloping areas for cattle grazing may lead to significant soil degradation and therefore we examined the influence of the slope gradient on soil degradation in pastures in a humid tropical mountainous area in northern Honduras. Understanding this relationship permits estimates of the physical carrying capacity of the soil, which in turn may help to improve livestock use within the study area. Variables examined included soil bulk density, texture, organic matter content and consistency as well as visual indicators of soil and vegetation degradation. There is a significant positive correlation between the bulk density as a proxy for soil degradation and slope gradient. Furthermore, it was found that when soils are water-saturated grazing leads to severe degradation. Together with visual indicators, these data show that paddocks with slopes less than 30% have a carrying capacity between 900 and 1900 Animal Units (AU) ha^− 1 year^− 1 and many are currently underutilized. Paddocks with slopes between 30 and 50% have a carrying capacity between 400 and 600 AU ha^− 1 year^− 1. Paddocks with slopes over 50% have the lowest carrying capacity: less than 200 AU ha^− 1 year^− 1. The latter are frequently over-used; most of them show clear signs of soil and vegetation degradation. Land use in these areas needs to change or their grazing management needs to be reorganized to adjust actual stocking rate to physical carrying capacity of the soils to prevent further degradation.     

Embryonic development in corkwing wrasse,Symphodus melops

Corkwing wrasse, Symphodus melops, is one of the main species used as cleaner fish to combat sea lice infestation in salmon aquaculture; however, there is little knowledge about its biology. Here, we describe the embryonic development of this species and examine the viability of the eggs under three temperature regimes. The experiments were conducted at three water temperature regimes, 12, 15, and 18°C, which resemble common sea water temperatures registered during the spawning season of corkwing wrasse at different latitudes along the Norwegian coast. Corkwing wrasse spawn small spherical eggs of 0.75–0.80 mm in diameter (mean 0.78, CV = 3.6%) with several oil droplets and go through eight developmental stages until hatching. The shortest hatching time was registered after 144 hr at 18°C and after 222 and 372 hr at 15 and 12°C, respectively. These observations provide important baseline biological information to advance the establishment of commercial rearing techniques and sustainable fishing management practices for this heavily exploited species.     

Fish fauna in Iberian Mediterranean river basins: biodiversity,introduced species and damming impacts

• 1. A basin approximation was used to analyse distribution patterns of different components of biodiversity (taxonomic richness, endemicity, taxonomic singularity, rarity) and conservation status of freshwater fish fauna in 27 Mediterranean Iberian rivers.
• 2. Basin area alone explained more than 80% of variation in native species richness. Larger basins featured not only a higher number of native species, but also more endemic and rare species and fewer diversified genera than smaller basins.
• 3. In contrast, smaller basins scored higher community conservation values, owing to their lower degree of invasion by introduced species.
• 4. The presence of dams was the most important factor determining the conservation status of fish communities, and it was also positively associated with the number of introduced species.
• 5. While the most important components of Iberian freshwater fish biodiversity are located in large basins, small unregulated basins feature better conserved fish communities.

Copyright © 2004 John Wiley & Sons, Ltd.     

Stock enhancement programme for black sea bream, Acanthopagrus schlegelii (Bleeker), in Hiroshima Bay, Japan: a review

This paper reviews the stock enhancement programme for black sea bream ( Acanthopagrus schlegelii ) in Hiroshima Bay. This bay is one of the biggest production areas for black sea bream in Japan, accounting for about 10% of the total catch of the species in this country in 2004. After intensive fishing pressure caused a drastic decline in the catch of the species in this bay in the 1970s, a stock enhancement programme was conducted in its northern part since 1982 to restore the depleted population. The number of black sea bream juveniles released in 1996 surpassed 9 million, representing the third main species stocked in Japan. Almost 1.4 million of these juveniles were released into Hiroshima Bay. The fast acclimatization of hatchery-reared juveniles released into the bay may have contributed to the recovery of landings in the late 1980s and 1990s. However, this recovery was accompanied by a reduction in the market price of black sea bream. Further studies to assess the effectiveness of the stock enhancement programme as well as the carrying capacity of Hiroshima Bay to maintain the stock of black sea bream at a stable, healthy level are desirable. The necessity of evaluating the secondary effects derived from using a reduced number of breeders as well as finding new markets are suggested.     

Effect of early weaning on performance, carcass and meat quality of spring-born bull calves raised in dry mountain areas

Sixteen bull calves were born in the Spanish Central Pyrenees in spring. They were either early (EW, 90 days of age) or normal weaned (NW, 180 days of age). At day 90, EW calves were placed on an intensive diet while NW calves were turned out with their dams to high mountain pastures. After summer, at day 180, NW calves were weaned and placed with EW calves on a common finishing diet until slaughter at the fixed age of 1 year. From birth to early weaning date, no performance differences appeared. However, EW calves gained faster (1.549 kg/day) than their unweaned counterparts (0.783 kg/day) from early to normal weaning date (P < 0.001). During the finishing period, NW calves showed compensatory growth, with a 44% higher ADG than EW calves (P < 0.001), with a similar feed intake and a better feed conversion ratio. Early weaned calves had a longer fattening phase than NW calves (264 vs. 158 days, respectively; P < 0.001) and thus total feed intake and feed costs were greater. When slaughtered at 1 year of age, EW and NW calves attained similar weight (489 vs. 510 kg, respectively; P > 0.05), but dressing percentage was higher for EW calves (56.9%) than for NW calves (55.2%) (P < 0.01), which led EW calves to have heavier carcasses, without differences in fat score or conformation. The different growth paths, the result of weaning management, did not affect meat tenderness, chemical composition and fatty acid profile, but affected meat lightness, with higher values for compensating calves (NW) than calves in continuous growth (EW). In conclusion, advancing weaning age modified calf performance without affecting substantially carcass characteristics, except for an improvement in dressing percentage, or meat quality.     

Effect of moderate Cu supplementation on serum metabolites, enzymes and redox state in feedlot calves

The aim of this investigation was to evaluate whether, in the nutritional management of commercial feedlots, copper (Cu) supplementation is justified to maintain the physiological requirements. This study compared beef calves fed concentrates with an average Cu basal content of 5 and 8 mg/kg in growing and finishing periods (10 animals) or supplemented with 15 mg/kg for each phase (20 animals) as regards production indices, metabolic parameters [glucose, nonesterified fatty acids (NEFA), cholesterol, serum urea nitrogen (SUN), creatinine, total serum protein (TSP), albumin, aspartate transaminase (AST) and γ-glutamyl transferase (GGT)] and markers of oxidative stress (reactive oxygen species (ROS) and serum antioxidant capacity (SAC)). Data were recorded at ages 12, 24 and 36 weeks. In general, Cu supplementation was neither detrimental nor beneficial for animal health and performance, and the levels of the measured metabolites and enzymes were within their normal ranges stated for feedlot with the same management during the whole study. However, in keeping with reported higher hepatic Cu levels at slaughter, animals on supplemented feed had higher GGT activities at the end of the finishing stage, although the difference was not statistically significant. On the other hand, lower SAC levels at the end of the growing period in the supplemented group suggest the possibility of a positive effect of Cu supplementation on redox state. Further research is necessary to clarify the potential role of Cu in limiting the ROS production associated with fattening diets, and to evaluate the hepatobiliary consequences of supplementation, including hepatic Cu accumulation.     

Seabird interactions and by‐catch in the anchovy pelagic trawl fishery operating in northern Argentina

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The Value of the Determination of Anti‐Aspergillus IgG in the Serodiagnosis of Canine Aspergillosis: Comparison with Galactomannan Detection

Diagnosis of canine aspergillosis is difficult using currently available methods. It often passes unnoticed or is diagnosed in the later phases of the disease. We developed an ELISA technique to detect anti‐Aspergillus antibodies in canine serum using an Aspergillus antigenic mycelial extract, which could then be used for the diagnosis of canine aspergillosis. We used a cut‐off of X + 3SD obtained from 20 control sera. The test was performed on 46 dogs with lesions indicating possible aspergillosis and gave nine positive results: one systemic mycosis, two discospondylitis, one uveitis, two bronchopulmonary processes and three rhinitis. We compared this methodology with the PLATELIA technique in the follow‐up of the affected dogs, obtaining the same limitations as in the diagnosis of human aspergillosis. We consider our ELISA technique using sera samples a speedy, safe and reliable method which enables us to follow up the evolution of the disease and the efficacy of the therapy chosen. A definitive diagnosis must still take into account the results of other tests such as clinical examination, radiographic studies, endoscopy and biopsy.