Farmed Strains Research Articles

A comparison of sea louse ( Lepeophtheirus salmonis) infection levels in farmed and wild Atlantic salmon ( Salmo salar L.) stocks

A total of 419 Atlantic salmon representing three wild stocks and two major and distinct Norwegian farmed strains were challenged with sea lice ( Lepeophtheirus salmonis) in replicated mixed stock tanks. Infection level, recorded as density of lice (lice abundance divided by fish body surface area), varied by up to 29% among the stocks and strains ( P<0.001) at 31 days post-infection. Post hoc tests revealed that the infection level observed on the wild Dale stock, displaying the lowest density of lice, was significantly lower than observed on the wild Vosso stock and the farm 2 strain, which displayed the highest and second highest infection levels, respectively. Pairwise comparisons of the differences in lice density among the other stocks, including the two farm strains, were not significant. Differences in infection level observed among the stocks and strains may reflect genetic differences in susceptibility to infection with sea lice among them.

Assessing genetic diversity of domestic populations of channel catfish ( Ictalurus punctatus) in Alabama using AFLP markers

Amplified fragment length polymorphism (AFLP) was used to analyze the genetic diversity of domestic stocks of channel catfish ( Ictalurus punctatus). Sixteen populations within Alabama (USA) were surveyed using five primer combinations. A total of 454 reproducible, polymorphic bands were detected from 282 individuals, with an average heterozygosity of 0.135. The percentage of polymorphic loci varied greatly within distinct populations, ranging from 18.26% to 100%. Research populations tended to have a lower percentage of loci polymorphic than farm populations. The estimated average F st value across all loci was 0.4456. However, this value dropped to 0.1763 when the Hicks Farm stock was excluded from the analysis. Cluster analysis by Jaccard's pairwise similarity coefficient indicated high similarity among individuals, with some population-specific clusters and with the Hicks Farm stock being highly distinctive. Nei's population-wise identity measures found all populations except the population from the Hick's Farm related with 96% similarity. The Hick's Farm stock was 34% similar to the other populations. The genotypic information derived from this study is consistent with the historical origins and management of catfish broodstocks. The results of this study suggest that many channel catfish farm strains in Alabama are genetically similar, but some very distinct differences exist. Such information has implications for future broodstock selection and management and for further analysis of interactions between domestic and wild populations of channel catfish.

Seawater adaptation and growth of post-smolt Atlantic salmon (Salmo salar) of wild and farmed strains

Atlantic salmon smolts (Salmo salar L.) of wild (Namsen) and farmed (AquaGen) strains were transferred to full-strength seawater (33‰) for 0 (initial control group), 0.5, 1, 2, 4, 8, 14, 30, 42 and 60 days at three different temperatures (4.3, 9.4 and 14.3 °C). Freshwater temperature in each tank was adjusted to test conditions 10 days prior to transfer. Physiological adaptation was monitored as changes in plasma growth hormone levels, gill Na+,K+-ATPase activity, plasma chloride levels and survival in seawater. Overall, smolts from the wild strain were better able to tolerate transfer to seawater than smolts from the hatchery strain. A delay in the osmotic disturbance and a prolonged period of osmotic stress were observed at the low temperature. Circulating GH levels increased transiently in all groups during the first 12–48 h in seawater and long-term GH levels were positively correlated with seawater temperature. Growth rates were influenced by temperature and strain, with the farmed smolts showing a higher growth than the wild smolts. Food Conversion Efficiency (FCE) was higher in smolts from the farmed strain, whereas no differences in daily food consumption were observed. Optimum temperature for FCE was calculated to be 10.5 °C, whereas the optimal temperature for growth in seawater was calculated to be 13.0 °C. We suggest that the observed differences in seawater tolerance, growth and food conversion probably are genetic and may reflect the fact that the hatchery fish have been bred for rapid growth for several generations.

Avaliação do perfil eletroforético das proteínas séricas em matrizes pesadas (Gallus Gallus Domesticus) da linhagem Avian Farm

O objetivo do presente trabalho foi determinar o perfil eletroforético das proteínas séricas em matrizes pesadas (Gallus Gallus Domesticus) sadias, da linhagem Avian Farm. Foram utilizadas 15 matrizes com 63 semanas de idade, provenientes do município de Conchas, São Paulo. Utilizou-se o método de biureto para a obtenção dos valores da proteína sérica total e a separação das frações protéicas pela técnica da eletroforese em gel de agarose, e a leitura do filme realizada por densitometria em 520nM. Obteve-se um total de sete frações, sendo que a beta1 - globulina e beta2 - globulina encontradas não foram citadas pelos autores consultados na literatura. A fração pré-albumina foi identificada em apenas seis das 15 amostras examinadas. Observou-se em cinco matrizes a divisão da gama - globulina em duas frações, denominadas gama - 1 e gama - 2, de acordo com suas mobilidades eletroforéticas. A relação albumina/globulina (A/G) encontrada corrobora com os autores citados, demonstrando que esta diminui com o aumento da idade.

Effects of domestication on growth physiology and endocrinology of Atlantic salmon (Salmo salar)

Selection programs for fish frequently target growth rate as a breeding goal, yet surprisingly little is known about which mechanisms underlying the growth process are being targeted. The aim of this study was thus to examine whether the process of artificial selection of Atlantic salmon (Salmo salar) that has resulted in higher growth rate resulted in underlying changes in the growth hormone (GH) – insulin-like growth factor I (IGF-I) axis of endocrine growth regulation. This was tested by comparing similarly reared seventh-generation farm salmon with wild salmon from the principal founder population of the farm strain at three life stages. Not unexpectedly, the domesticated fish outgrew their wild counterparts; this was most evident in salt water, where they averaged three times the weight by the end. Pituitary GH content was positively correlated with growth rate and correspondingly was significantly higher in the faster growing domesticated fish than in the wild fish. Plasma GH levels were also significantly higher in the domesticated fish, whereas IGF-I levels did not differ. These findings provide some of the first direct evidence indicating a link between domestication selection for growth and its endocrine regulation, whereby individuals with more active endocrine growth regulatory components are targeted.

An attempt to eradicate porcine reproductive and respiratory syndrome virus (PRRSV) after an outbreak in a breeding herd: eradication strategy and persistence of antibody titers in sows

A sow multiplier herd of high health status experienced an outbreak of porcine reproductive and respiratory syndrome (PRRS). In an effort to eradicate the PRRS virus, breeding animals were deliberately infected with the farm strain by exposing them to whole piglets and minced tissues of piglets that died in the farrowing crates. The herd was then closed for 23 weeks. No clinical signs were observed after the initial outbreak and there was no evidence of virus circulation in the herd verified through serological testing by PRRS ELISA, during the 2 years after the eradication attempt. Approximately one third of sows present at the time of the outbreak were still seropositive 20 months after the deliberate infection.

PCR–RFLP analysis of the mitochondrial ND-3/4 and ND-5/6 gene polymorphisms in the European and East Asian subspecies of common carp ( Cyprinus carpio L.)

Polymorphism within the mitochondrial NADH-3,4 dehydrogenase ( ND-3/4) and NADH-5,6 dehydrogenase ( ND-5/6) gene regions was studied by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) analysis among common carp populations belonging to the European (two farmed strains and three wild populations) and East Asian (Amur wild carp, Vietnamese wild carp and Japanese Koi carp) subspecies, Cyprinus carpio carpio and C. c. haematopterus, respectively. Polymorphism was detected using eight and six restriction enzymes, respectively, and a total of seven composite haplotypes were identified. Both distance-based and maximum likelihood phylogenetic inference methods clustered the haplotypes into four distinct groups—the European (two haplotypes), Amur (two haplotypes), Vietnamese (two haplotypes) and Koi (one haplotype), and their distributions strictly follow the geographic origin of populations. The populations are clustered into two highly divergent groups (average net nucleotide divergence, 2.4%), the European and the East Asian populations, suggesting an ancient separation. Six enzymes ( HinfI, AluI, HpaII and TaqI at ND-3/4; Eco47I and BsuRI at ND-5/6) yielded diagnostic restriction sites for discriminating between the European and East Asian maternal lineages that can be applied to monitoring of genetic purity of the European farmed strains.

Behavioural and heart rate responses to predation risk in wild and domesticated Atlantic salmon

Artificial culture may relax the selective pressures from predators, thereby altering behavioural and heart rate responses to predation risk. Culture may also impose new selection that adapts fish to confinement. Predictions from these hypotheses were tested by comparing seventh-generation farm Atlantic salmon (Salmo salar) with wild Atlantic salmon from the principal founder population of the farm strain. Wild age 1+ salmon had higher standard heart rates and showed a more pronounced flight and heart rate response to a simulated predator attack than did farmed salmon. However, wild fish were closer to the model predator at attack, which may have accentuated these differences. Both strains habituated to the threat, showing less response to the second attack than to the first. In contrast with age 1+ fish, wild age 2+ salmon had lower standard heart rates than farmed fish. Moreover, in age 2+ salmon, domestication effects were less clear and the response to predation threat considerably weaker, suggesting that environmental effects of culture override genetic effects as time in captivity increases. Domestication selection may thus alter reaction norms of farmed animals over environmental gradients and time. This should be considered when attempting to predict the consequences of release or escape of domesticated animals in the wild.

Microsatellite DNA variation in wild populations and farmed strains of turbot from Ireland and Norway: a preliminary study

Turbot Scophthalmus maximus is the focus of a rapidly expanding aquaculture industry, while at the same time wild catches appear to be in decline. As a preliminary investigation into the effects of hatchery rearing, genetic variation at three polymorphic microsatellite loci was assessed in two wild populations and two farmed strains of turbot, from Ireland and Norway. Although a considerable loss of rare alleles was observed in the Irish farmed strain, no statistically significant reductions were found in mean heterozygosity or allelic diversity in farmed strains compared to wild populations. Significant genetic heterogeneity was found between wild and farmed samples from each country but not between the two wild populations. Genetic differentiation between the farmed strains was presumed to be caused by drift in the hatcheries. The utility of these particular microsatellite loci in comparing these samples and the importance of molecular genetic testing of farmed strains is stressed.

Genetic changes in an Atlantic salmon population resulting from escaped juvenile farm salmon

The study was undertaken on three adjacent rivers in NW Ireland, on one of which an Atlantic salmon Salmo salar freshwater juvenile rearing unit is situated. Two markers which distinguished farm and wild populations were used. An Ava II‐B RFLP in the ND1 region of mtDNA was at a frequency of 0.58 in the farm strain but absent in the wild populations. Allele E at minisatellite locus Ssa‐ A45/2/l was at a frequency of 0.91 in farm samples, but at a maximum of 0.41 in the populations in the two rivers adjacent to the one with the juvenile rearing unit. The farm strain showed a significant reduction in mean heterozygosity (0.281 ± 0.057), over three minisatellite loci examined, compared to wild samples (0.532 ± 0.063). The occurrence of farm genotypes and the independent occurrence of mtDNA and minisatellite markers in several parr samples from the river indicated that escaped juvenile salmon completed their life cycle, bred and interbred with native fish, upon their return to the river. Escaped fish homed accurately, as adults, to the site of escape, i.e. the area adjacent to the hatchery outflow in the upstream part of the river. Breeding of males in the lower part of the river was also indicated but this could have been due to mature male parr which had moved downstream. The return of adults of farm origin to the river to breed was indicated by the presence of the Ava II‐B haplotype in adults netted in the estuary.

Genetic improvement of farmed tilapias: Biochemical characterization of strain differences in Nile tilapia

Four African wild strains (Egypt, Ghana, Senegal and Kenya) and four established Asian farmed strains of Nile tilapia, Oreochromis niloticus (popularly known in the Philippines as ‘Taiwan’, ‘Thailand’, ‘Singapore’ and ‘Israel’) were analysed electrophoretically at 30 protein loci to estimate genetic differences among the strains. All strains shared alleles at 14 monomorphic and 16 variable loci. Among the African strains, characteristic allele frequency differences were observed at AAT-1*46 for Ghana and Senegal, ADH*83 for Kenya, ADH*120 for Senegal, G3PDH-2*300 for Egypt, IDDH*67 for Senegal, sMDH-1*120 for Kenya and SOD*150 for Senegal. Genetic distance values among the strains revealed a clustering of the farmed strains with Egypt and Ghana O. niloticus, a slight separation of the Senegal strain and a larger separation of the Kenya strain. This profile may reflect the origins of the few founder populations of this species previously introduced to Asia. It also confirms the wider genetic divergence of the Kenya strain (O. niloticus vulcani) from the others studied here, which are all O. n. niloticus. Observed heterozygosities of the strains ranged from 0.026 to 0.071, with the African wild strains the lower values (mean Ho = 0.036) and the farmed strains the higher ones (mean Ho = 0.056). The implications of these results to the ongoing tilapia genetic improvement programme in the Philippines are discussed.

Antibiotic resistance in bacteria isolated from three freshwater fish farms and an unpolluted stream in Denmark

Resistance profiles against two antibiotics, oxytetracycline and oxolinic acid, were determined for 296 bacterial strains isolated from three fish farms (202 strains) and from an unpolluted stream (94 strains) in Denmark. Resistance against oxytetracycline (25 μg/ml) was seen amongst 15% (29 strains) from fish farms and for 6% (6 strains) from an unpolluted stream. Oxolinic acid resistance was also more prevalent amongst fish farm strains where 27% (53 strains) grew in the presence of 12.5 μg/ml oxolinic acid. Only 16% (15 strains) of isolates from the unpolluted stream were resistant against oxolinic acid. Bacteria from the fish farms may spread with the water circulation and, although the resistance frequencies found in this study were not statistically different, the use of chemotherapeutics may add to the environmental resistance pool. Two types of inhibition curves were observed. One showed instant inhibition at a given concentration of antibiotic. The other curve showed a slow decrease in growth with increasing concentration of antibiotic. Six percent (13 strains) and 4% (4 strains) from fish farms and an unpolluted stream were resistant to both antibiotics. The isolates from the fish farms and the unpolluted stream were identified as Vibrionaceae, Enter-obacteriaceae, Alcaligenes spp., Acinetobacter spp., Pseudomonas spp., Moraxella spp., Moraxella-like and Shewanella putrefaciens. Fifteen percent were Gram-positive organisms of which one half were resistant to oxolinic acid. Resistance profiles for the Gram-negative bacteria were, in general, independant of species or groups and no difference was seen between isolates from three different trout farms exposed to different environmental stress.

Genetic improvement of farmed tilapias: the growth performance of eight strains of Oreochromis niloticus tested in different farm environments

Results from two consecutive generations of testing to evaluate the growth performance of eight different strains of Nile tilapia ( Oreochromis niloticus) in eleven different farm environments are reported. The eight strains include four new strains recently imported to the Philippines from Egypt, Ghana, Kenya and Senegal; and four established Asian farmed strains popularly known in the Philippines as ‘Israel’, ‘Singapore’, ‘Taiwan’ and ‘Thailand’ strains. The test environments were chosen to cover a wide range of Philippine tilapia farming systems, from simple ponds, as used by backyard farmers, to more intensive systems: fertilized ponds, ponds fertilized with on-farm agricultural residues, rice-fish systems, cages, and three tilapia hatcheries (satellite stations) located in different regions of the island of Luzon. During the first generation trials in 1989, individually tagged fingerlings bred from the founder populations (total 7652) were communally reared in all test environments for about 90 days. In 1990, the second generation trials were made as a part of a complete diallele crossing experiment (8×8 strains). Data on 3420 individually tagged fingerlings of pure strains communally reared in eight test environments were used for the study. The results indicated highly significant differences among the growth performances of the eight strains. Moreover, with the exception of the Ghana strain, the newly introduced African wild strains performed as well as or better than the most widely farmed Asian strains. The importance of strain×test environment interaction over the investigated range of test environments was low. The implications of these results for developing a breeding program for tilapias in the Philippines are discussed.

The resistance to eighteen toxicants of a strain of Musca domestica L. collected from a farm in England

AbstractA sample of houseflies initially collected from a pig farm and found to be resistant to bendiocarb, DDT, gamma‐HCH, pyrethrins + piperonyl butoxide (PB), tetrachlorvinphos and trichlorfon, was tested for resistance to knockdown by other toxicants. At the KD50 response level, resistance factors were obtained for: permethrin (× 141), deltamethrin (×96), bioresmethrin + PB (×37), resmethrin + PB (×33), fenitrothion (×94), bromophos (×58), iodofenphos (×42), pirimiphos‐methyl (×30), dichlorvos (×22), dimethoate (×9), diazinon (×8), methomyl (×4) and methomyl + PB (×4). The slopes of the dose–response lines were lower for the farm strain than for a susceptible strain. This resulted in an increase of resistance factors at the KD95 level by an average of × 1.6. The houseflies on the farm could not be controlled using space sprays of pyrethrins + PB, although resistance to this toxicant was only ×12. However, control was achieved with a methomyl bait.

Reproductive Performance in Wild and Game Farm Mallards

Reproductive performance was studied in five strains of mallards with different degrees of wildness. Game farm mallards had a longer breeding season, higher egg production, larger clutch size, and higher male fertility than wild mallards. Incubation time and maximum emergence time were also longer for eggs laid by game farm dams than for eggs laid by wild dams. There was no significant difference between strains for embryonic mortality and hatchability. Hybrid strains were intermediate between the game farm and the wild strain in traits where significant differences were found. Although game farm and wild mallards differed substantially in several of the reproductive traits examined, and these differences may have a direct influence on the reproductive success of game farm strains in the wild, none seems to present any postcopulatory isolating mechanisms between these two strains of mallards.

The development of resistance to certain organophosphorus and carbamate ixodicides by the blue tick, Boophilus decoloratus (Koch) (Acarina, Ixodidae), in Rhodesia

AbstractEight strains of Boophilus decoloratus (Koch) are described from farms in the High veld area of Rhodesia. All eight strains showed resistance to a number of organophosphorus ixodicides and four showed additional resistance to the carbamate, carbaryl. This is the first recorded resistance to these two groups of ixodicides in Rhodesia.Biochemical studies on the Alicedale West Farm strain indicated a level of resistance between that of the Berlin strain of B. decoloratus and the Biarra strain of B. microplus (Can.).

A Vaccination Procedure Against Trypanosoma Cruzi Infection in Mice by Nonspecific Immunization

Abstract There are previous reports dealing with vaccination against experimental infection with Trypanosoma cruzi in mice. They have varied from the use of avirulent, killed, or irradiated strains to subcellular materials and the use of other kinetoplastic flagellates (1, 2). Although these procedures have been promising, none of the methods presently studied has resulted in absolute protection under conditions of challenge with large numbers of parasites. The aim of the experiments reported here was to explore the possibility of protecting mice against T. cruzi infection by BCG immunization, a treatment that has been shown in other systems to enhance nonspecifically immunity (3–6). Mice of the Carworth Farm strain (CF1) aged 1.0 to 1.5 months were used uniformly throughout these experiments. Development of the T. cruzi infection was checked routinely by determination of parasites in blood every 5 days after challenge infection and histopathologic studies of the heart at the time of death.

IMMUNOCHEMICAL STUDIES ON BLOOD GROUP SUBSTANCES IN R FORM BACTERIA

1. Anti-A, anti-B and anti-C agglutinin, and anti-B and anti-C precipitin produced in anti-R form Shigella dysenteriae immune chicken serum were all absorbed strongly with D-galactose, lactose, raffinose, D-galactosamine and N-acetyl-D-galactosamirte, and weakly with L-arabinose. Between the anti-A, anti-B and anti-C agglutinin. there was no difference except in the amount of sugar, required for the absorption, Further, the anti-C agglutinin and the anti-C precipitin were slightly inhibited in their action with D-glucose, N-acetyl-D-glucosamine, L-rhamnose and D-xylose as ell Was by the above-mentioned sugars.2. Galactose, extracted from R form Escherichia coli O86, could absorb well also the above-mentioned R form specific antibodies. Accordingly an element principally composed of galactose was considered to determine the blood group specificity of R form strains. And in fact galactose was demonstrated in all R form strains.3. R form Escherichia freundii B124 contained group A substance, which was hardi y demonstrable in S form strains of this bacterium. In rabbit serum immunized with this R form strain, anti-A agglutinin and anti-A precipitin were demonstrated. And these antibodies were inhibited in their reaction, strongly with N-acetyl-D-galactosamine, and weakly with N-acetyl-D-glucosamine.4. In Sh. dysenteriae, R form strains containd glucose, galactose, hexosamine and N-acetylhexosamine, lacking rhamnose. which was found in type S strains. In Salmonella poona, R form strains contained glucose, galactose and hexosamine, lacking fucose found in S farm strains. Also N-acetylhexosamine was difficult to demonstrate in R form strains. In Salmonella riogrande, and E. freundii B90, R form strains contained glucose, galactose, hexosamine and N-acetylhexosamine, lacking mannose found in S form strains. In Salmonella paratyphi B, R form strains contained glucose, galactose, hexosemine and N-cetylhexosamine. lacking abequose, rhamnose and mannose found in S form straius. In E. coli O86, R form strains contained glucose, galactose, hexosamine, and N-acetylhexosamine, lacking fucose found in S form strains. In. E freundii B124 glucose, galactose, hexosamine and N-acetylhexosamine were found both in S and R forms. In this way, with variation from S to R, methylpentose, desoxymethylpentose and mannose disappeared.5. Sugar which determines group O (H) specific activity of S form strain of Sh. dysenteriae, and that which determines groups A, B and C specific activities of R form strain of this bacterium are both considered to contain galactose as a principal component. And difference between these blood group speific activities is assumed to consist in the mode of combination of galactose.6. Fucose, which determines group O (H) specific activity of S. poona S form, was absent, together with th : s activity, in R form strain of this bacterium.7. N-acetylhexosamine, especially N-acetylgalactosamine, which determines groups FA and A specific activities of S form strain of S. paratyphi B, S. riogrande and E. freundii B90 was slightly demonstrated also in polysaccharide of R form. N-acetylhexosamine was further demonstrated in S form E. freundii B124, which did not show group A activity, and in R form strain of this bacterium, which exhibited this acitvity. The former, which contained more N-acetylhexosamine than the latter could nevertheless demonsrate no A activity. It is therefore considered that the blood group A activity may be attributed to the mode of combination of N-acetylhexosamine, especially of N-acetylgalactosamine.