Active tension‐extension splints: A novel technique for management of congenital flexural deformities affecting the distal limb in the foal

A variety of methods are described for managing distal limb flexural deformities in the foal, including intravenous oxytetracycline and splint or cast use. This case series describes a novel technique that creates an ‘active tension‐extension splint’ by wiring the toe into a custom‐made fibreglass splint and therefore into active extension. A dorsal fibreglass splint is made by halving a cast that is set around the affected leg with padding underneath it, so that it is sculpted to a more appropriate anatomical shape. Cerclage wire is placed through the toe and the dorsal aspect of the splint, then tightened to pull the limb into active extension. Foals with distal limb flexural deformities that were treated in this way were followed up by examination of hospital records and telephone questionnaire. Records were examined for 13 foals treated between 2004 and 2010. One foal developed septic osteitis of the distal phalanx due to suspected laminar penetration; other post operative complications seen were bandage sores and minor cosmetic scarring. Out of 10 foals where follow‐up by questionnaire was available, 8 had complete resolution of their deformity following active tension‐extension splinting, one required inferior check ligament desmotomy for complete correction and one had carpal flexural deformities that did not resolve. All that survived to adulthood are sound and have achieved their intended purpose. This previously unpublished technique using a wire through the toe to create an active tension‐extension splint has a high success rate for correction of congenital flexural deformities affecting the distal interphalangeal and metacarpo‐/metatarsophalangeal joints in the foal. The majority of post operative complications are minor and easily managed. This is a simple technique that can improve the management of neonatal distal limb deformities both in a hospital situation and for equine practitioners in the field.     

Early weaning in meagre Argyrosomus regius: Effects on growth,survival, digestion and skeletal deformities

Meagre Argyrosomus regius is considered a new species for the diversification of finfish aquaculture in the Mediterranean. Several bottlenecks have been identified by producers, and among them, the necessity to establish early weaning protocols to reduce production costs. In this study, two experiments were carried out with meagre larvae from 2 to 35 days post hatch (dph) using different weaning strategies, including the early introduction of artificial diets and the reduction of Artemia metanauplii to half of the normal amounts. A high frequency of cannibalism and high variability in growth rate and survival were obtained in one of the trials and several changes were introduced (reduction of light intensity, higher frequency of food distribution) in the second trial to increase the survival rate. In both trials, weaning started before the complete morphological and functional development of the stomach; thus, pancreatic enzymes, mainly trypsin and lipase tended to be more active in early weaned larvae compared to the control groups. Early weaning delayed the development of the stomach formation and secretion of acid proteases, which may explain the lower growth rates observed in our study. The effect of weaning on skeletal development was also studied and in this sense the results obtained showed no major influence of the early weaning on the incidence of skeletal deformities. Weaning of meagre larvae can be performed as early as 12 dph, but important aspects such as avoiding cannibalism and co‐feeding live prey and artificial diets for at least 5 days were recommended.     

Morphological deformities in mud crab Scylla serrata juveniles exposed to antibiotics during the larval stage

The effects of antibiotics on the external deformities, growth and survival of mud crab Scylla serrata larvae and juveniles were determined. Zoeae were exposed to oxytetracycline (OTC) (0, 3.0, 6.0, 9.0, 12 mg L^?1) and furazolidone (FZD) (0, 0.5, 1.0, 1.5, 2.0 mg L^?1) in the first and second experiments, respectively, until the late megalopa. The crab instars were grown in nursery tanks for 1 month. Larvae survived until megalopa only at 3.0 and 6.0 mg L^?1 OTC or 0.5 and 1.0 mg L^?1 FZD. These four concentrations were run simultaneously in another experiment. Morphological deformities in zoea 5 were bent dorsal, rostral and furcal spines. There was no significant difference (P > 0.05) on the deformities of zoea 5 in 3.0 and 6.0 mg L^?1 OTC and 0.5 and 1.0 mg L^?1 FZD. Significantly (P < 0.05) higher survival and faster growth were attained in 3.0 mg L^?1 OTC and 0.5 mg L^?1 FZD. Deformities observed in juveniles were fused frontal and lateral spines, asymmetrical and depressed tip of abdominal flap and gap between sternites. High percentage occurrence of deformities was observed in the 6.0 mg L^?1 OTC and 1.0 mg L^?1 FZD in the first and third experiments, respectively. There was no significant difference (P > 0.05) observed in the survival of juveniles in OTC and FZD treatments. However, growth was significantly (P < 0.05) faster in lower concentrations of the two antibiotics. The study shows the effects of OTC and FZD in the morphology of mud crab. Therefore, there is a need to eliminate the use of antibiotics and find alternatives.     

Effects of dietary calcium levels on growth and tissue mineralization in Japanese seabass,Lateolabrax japonicus

A feeding trial was conducted to investigate the effects of different levels of calcium (Ca) on growth and tissue mineralization in Japanese seabass, Lateolabrax japonicus. Six experimental diets were formulated to contain different levels of Ca (2.9, 4.2, 6.5, 7.9, 10.2 and 31.0 g kg^?1) from dietary ingredients and Ca‐lactate·5H₂O. The diets were fed to three triplicate groups of Japanese seabass (initial weight, 12.5 ± 0.0 g) for 56 days. Dietary Ca had no significant effect on survival or feed efficiency; however, the highest Ca (31.0 g kg^?1) diet significantly reduced weight gain, feeding rate and whole‐body and muscle protein and lipid contents, as well as serum Ca concentration and alkaline phosphatase activity. A significant reduction in vertebral Ca, P, Zn, Fe and Mn contents and scale Ca, P, Mg and Mn contents was observed in Japanese seabass as dietary Ca level increased. Deformed fish were primarily found in the 2.9 and 31.0 g Ca kg^?1 groups, indicating that these fish had poor bone mineralization.     

Heritabilities and correlations of deformities and growth‐related traits in the European sea bass (Dicentrarchus labrax,L) in four different sites

Skeletal deformities are important traits for aquaculture as they induce slow growing and low market value. We studied their genetic determinism and their interactions with the environment at the ongrowing stage in 5839 European sea bass from a partial factorial mating of 33 sires and 23 dams, reared in four sites. All families were mixed, and fish were first reared in one site (site B) until 35 g mean weight, then distributed to the four sites. A posteriori reconstruction of pedigree with microsatellites was used. Deformities were scored internally at slaughtering, and externally from photographs. Site B, where all fish were initially stocked until 35 g and exposed to forced swimming because of fast water current showed the highest rate of deformities with 83% and 65% from internal and external scoring respectively. Heritability on the underlying scale was h² = 0.25 ± 0.03 across all sites, and varied little between sites, while genetic correlations of deformities between sites were always high (>0.85). Genetic correlations between deformities and daily growth coefficient were variable between sites(r_A = 0.50 ± 0.09, 0.43 ± 0.10, 0.32 ± 0.10, 0.18 ± 0.10 for sites A, B, C, D respectively) and were positively linked with the average growth rate in each site. These results pointed out that there could be a relation between growth rate and the evolution of deformities at the grow‐out stage.     

Establishing an upper level of intake for vitamin A in Atlantic salmon (Salmo salar L.) postsmolts

The vitamin A (VA) concentration in salmon aquaculture feeds is varying and may lead to sublethal adverse effects. In this study, 135 g Atlantic salmon postsmolts were given eight diets in duplicates with 6, 12, 26, 55, 82, 112, 360 and 749 mg retinol (ROL) kg⁻¹ for 116 days. Subsequently, fish given 6, 82 and 749 mg ROL kg⁻¹ were transferred to a common net pen and given a standard commercial diet for further 28 weeks. Feed conversion rate, liver functionality and markers of VA homoeostasis were not negatively affected by dietary VA level, but chronic high VA intakes led to adverse effects on growth and bone health. In plasma, there was an antagonistic effect of dietary ROL on circulating 1,25 (OH)₂ vitamin D₃ (calcitriol). Moreover, a dose–response of VA on craniofacial deformities, condition factor and vertebral morphometry and mechanical strength was observed. Vertebral deformities were observed after 28 weeks on a standard diet and not immediately after the 116 days on the experimental diet. Elevated VA is a risk factor for bone deformities, and the dietary intake of VA should not exceed 37 mg ROL kg⁻¹ body weight day⁻¹ in Atlantic salmon postsmolts.     

Supplementation of tryptophan and lysine in Diplodus sargus larval diet: effects on growth and skeletal deformities

Amino acids are the building blocks for growth and the major energy source during fish larval stages. Deficient amino acids can be supplemented in the diets, overcoming problems such as low growth rates and skeletal deformities. In this study, three experimental diets were tested: a balance diet supplemented with lysine, a balance diet supplemented with tryptophan and a control with no supplementation. Trials were conducted with Diplodus sargus larvae from 1 to 25 days after hatching (DAH). A microencapsulated diet was introduced at 15 DAH in co-feeding with live feed and from 20 DAH larvae were fed only this diet. The effect of the supplemented diets was assessed in terms of survival, growth rate, skeletal deformities, ammonia excretion and activity of amino acid catabolism enzymes. The results showed a similar survival in all treatments. However, larvae given tryptophan supplementation had a lower weight on 25 DAH. No significant differences were found in ammonia excretion, frequency or type of deformities or enzymatic activity. Tryptophan and lysine supplementation failed to improve larval growth, survival or larval quality.     

Development of deformities at the vertebral column in Diplodus sargus (L., 1758) early larval stages

One of the bottleneck problems of Diplodus sargus farming is a high incidence of skeletal deformities at the vertebral column. In this study, the pattern of vertebral deformities were determined in three different larval batches from 2 to 30 days after hatching (DAH). During this period, 60 larvae per spawn were observed at 2, 8, 13, 15, 18, 21, 23, 25, 27 and 30 DAH and the different types and frequency of vertebral column malformations were registered. Deformities started from 8 to 13 DAH, when the percentage of deformed larvae rose from approximately 5% to 40%. At 15 DAH, skeletal malformations had frequencies up to 80% of the observed larvae. Serious malformations such as kyphosis, scoliosis and lordosis were observed at 18 DAH but seldom in percentages higher than 15%. Vertebral fusions and compressions especially affected the preurostyle region. Abnormal shape vertebrae were more frequent between vertebrae 15 and 21. Other malformations observed were hypertrophic vertebrae, more common in the trunk and caudal regions, reaching percentages higher than 50% in the former. This study has useful information concerning skeletal malformations at the vertebral column of D. sargus larvae, as it identifies the main deformities observed and the ages of highest incidence.     

Association of a lordosis-scoliosis-kyphosis deformity in gilthead seabream (Sparus aurata) with family structure

Skeletal deformities constitute a major problem for aquaculture industry by decreasing the final value of the fish. An analysis of skeletal malformations in 11,640 fish was performed considering families and triplicates per family. Thirtynine different skeletal abnormalities were detected, such as lordosis, vertebral fusion, absence of one or both operculum, bent-jaw, etc. Moreover, a new unusual complex spinal column deformity consisting of a consecutive repetition of lordosis, scoliosis and kyphosis (LSK) from the head to the caudal fin was described. This syndrome was statistically associated with the family structure (Z_{2H–family,LSK}=3.49; p<0.05). The incidence of this deformity was 0.2% in the whole population, and 6.5% within the affected family (2H). The environmental and genetic causes are discussed.     

Review of the principal diseases affecting cultured meagre (Argyrosomus regius)

Argyrosomus regius was recently introduced in European aquaculture as a promising species for diversification and with high potential for expansion in the coming years. The reports on pathologies affecting this species are still scarce in the bibliography, however, they can severely affect production and result in major economic losses. Some few reports were made on outbreaks and mortalities associated with the presence of bacteria such as Vibrio anguillarum and Photobacterium damselae subsp. piscicida. Although no viral diseases have been recognized as affecting meagre, it is known that meagre can be an asymptomatic carrier of two genotypes of nodavirus, the striped jack nervous necrosis virus and red‐spotted grouper nervous necrosis virus. Up‐to‐date, parasites affecting meagre are included in the genera Monogenea, Nematoda and Dinoflagelate, but without major mortality outbreaks associated to this type of infections. Osteological deformities have been observed in all life stages particularly affecting the axial system in larval and early juvenile specimens, with a higher incidence in the vertebral column, being affected by vertebral fusions, lordosis and kyphosis. With this review the authors provide an overview of all the pathological and non‐pathological diseases affecting aquaculture produced meagre and provide a comprehensive overview of possible problems for the industry.