Maslinic acid,a natural triterpene,and ration size increased growth and protein turnover of white muscle in gilthead sea bream (Sparus aurata)

Maslinic acid (MA) is a pentacyclic triterpene used, at experimental level, as an additive to stimulate growth, protein‐turnover rates and hyperplasia in fish. In this experiment we have studied the effects of feeding with MA at daily fixed ration of 10 g kg^?1 of body mass, on growth, protein‐turnover rates and nucleic acid concentration in white muscle of gilthead sea bream grown in a local fish farm. The experimental groups contained 0 (control), 50 (MA₅₀) and 100 (MA₁₀₀) mg MA per kg of diet. Two groups were provided feed ad libitum (control AL and MA₁₀₀AL), while three were given a fixed ration (control R, MA₅₀R, and MA₁₀₀R). We have determined the following: growth rate; nucleic acid and protein levels; relative and absolute protein‐accumulation (K_G, A_G), synthesis (K_S, A_S) and degradation (K_D, A_D) rate, protein‐synthesis capacity (C_S), protein‐synthesis efficiency (K_RNA), protein‐synthesis rate per DNA (K_DNA) and protein‐retention efficiency. At the end of the experiment, higher body weights and muscle growth rates were found in both groups of fish fed with 100 mg MA per kg of diet. Feed‐efficiency rate, protein‐efficiency ratio and protein productive value, were higher in the MA₁₀₀AL group than in control AL. Fractional and absolute protein‐synthesis and degradation rates in white muscle of MA₁₀₀AL and MA₁₀₀R fish were higher than in the control, resulting in a higher protein‐accumulation rate and tissue growth. Total DNA content, indicated cell hyperplasia, was higher in MA₁₀₀AL and MA₁₀₀R than its respective controls. Studies of optical and electronic microscopy corroborated these results. These findings indicate that MA added to the diet can stimulate the growth, white‐muscle protein‐turnover rates and tissue hyperplasia in gilthead sea bream.     

The consequences of diet limitation in juvenile threespine stickleback: growth,lipid storage and the phenomenon of compensatory growth

Many organisms exhibit compensatory growth (CG), an accelerated growth rate during recovery from periods of low nutrient resources. Despite numerous studies, many aspects of CG, particularly fine‐scale temporal effects early in life, remain poorly understood. We manipulated early‐life feeding regimens in threespine stickleback (Gasterosteus aculeatus) to study compensatory responses in growth rate and lipid storage during the first growing season. Laboratory‐reared stickleback, including ancestral oceanic and derived freshwater populations, were divided into three age‐specific dietary treatment groups – DPR1, DPR2 and DPR3 – which were exposed to a half‐ration nutrient deprivation for 30 days at the onset of 2, 3 and 4 months of age, respectively. We hypothesised that these month‐long periods of nutrient deprivation would result in strong, yet variable CG responses across stickleback populations and dietary treatments following a return to optimal ration levels. The youngest two age classes of fish (DPR1 &and DPR2) exhibited strong CG responses, matching growth rates and lipid generation levels seen in control fish fed an ad libitum diet. The oldest nutrient‐deprived group (DPR3) showed a reduced CG response, with body growth recovering only partially, and lipid levels exhibiting even less recovery. Our results demonstrate that compensatory growth responses in juvenile stickleback depend on the timing of deprivation during the first growing season and further that responses to late‐season deprivation have favoured development of a larger body frame entering the overwintering season over lipid regeneration.     

Chicken anemia virus and fowl adenoviruses: association to induce the inclusion body hepatitis/ hydropericardium syndrome

The effects of a simultaneous and/or a subsequent coinfection with chicken anemia virus (CAV) isolate 10343 and fowl adenovirus (FAV) isolate 341 in specific-pathogen-free light chickens were evaluated. The simultaneous coinfection was conducted by the intramuscular route, whereas the subsequent coinfection trial considered FAVs administered orally. In trial 1, 20-day-old chickens simultaneously coinfected with CAV (10343) and FAV (341) intramuscularly (i.m.) showed 55% mortality and characteristic signs and lesions of inclusion body hepatitis/hydropericardium (IBH/HPS). In contrast, birds singly infected with FAV i.m. showed 10% mortality due to IBH/HPS. Trial 2 showed that birds receiving FAV 341 orally at day 7 post-CAV intramuscular infection (group A) developed a mild form of IBH/HPS with presence of inclusion bodies (INIBs) in 60% of the group and virus-neutralizing antibodies against FAV 341. Group B (FAV orally 14 days after CAV) showed significant decreased weight gain, nonspecific microscopic lesions in the liver, spleen, bursa, and thymus, and an antibody response against FAV 341. However, no INIBs could be detected in the hepatocytes of these chickens. Group C (FAV orally 35 days after CAV) showed nonspecific histopathologic changes in the liver and no antibody response to FAV. The oral single infection with FAV isolate 341 induced neither mortality nor macroscopic lesions of IBH/HPS in the birds. The present results corroborate previous reports on pathogenicity of Chilean FAV isolates, which suggest that synergism with other viruses or prior immunosuppression is necessary to produce IBH/HPS in chickens. These results also suggest that the susceptibility of chickens to FAV oral infection resulting in IBH/HPS varies throughout the course of CAV infection.     

Amoebicidal and giardicidal compounds from the leaves of Zanthoxylum liebmannianun

The crude ethanol extract from the leaves of Zanthoxylum liebmannianum exhibited inhibitory effect on the reproduction of trophozoites of Entamoeba histolytica (IC(50)=3.48 microg/ml) and Giardia lamblia (IC(50)=58.00 microg/ml). From this extract, asarinin, hyperin, beta-sitosterol, and beta-sitosterol glucoside were isolated. Among them, asarinin was the most active with IC(50) values of 19.86 microg/ml for E. histolytica and 35.45 microg/ml for G. lamblia. The remaining compounds showed moderate activity against both parasites.     

Zebrafish (Danio rerio) as an animal model for bath infection by Flavobacterium psychrophilum

Flavobacterium psychrophilum is the causative agent of bacterial cold-water disease and rainbow trout syndrome in freshwater salmonid fish worldwide, generating injuries and high mortality rates. Despite several studies on this bacterium, the infection mechanism remains unknown due to limitations in the employed animal models. In this work, we propose using zebrafish (Danio rerio) as a model for studying bacterial pathogenicity. To substantiate this proposal, zebrafish infection by F. psychrophilum strain JIP 02/86 was characterized. Zebrafish larvae were infected using the bath method, and morphological changes and innate immune system activation were monitored using transgenic fish. Salmonid-like infection phenotypes were observed in 4.74% of treated larvae, as manifested by fin, muscle and caudal peduncle damage. Symptomatic and dead larvae accounted for 1.35% of all challenged larvae. Interestingly, infected larvae with no infection phenotypes showed stronger innate immune system activation than specimens with phenotypes. A failure of function assay for myeloid factor pu.1 resulted in more infected larvae (up to 43.5%), suggesting that low infection rates by F. psychrophilum would be due to the protective actions of the innate immune system against this bacterium in zebrafish larvae. Our results support the use of zebrafish as an infection model for studying F. psychrophilum. Furthermore, the percentage of infected fish can be modulated by disturbing, to varying extents, the differentiation of myeloid cells. Using this evidence as a starting point, different aspects of the infection mechanism of F. psychrophilum could be studied in vivo.     

Estimates of environmental effects and genetic parameters for body measurements and weight in Brahman cattle raised in Mexico

A Derivative Free Restricted Maximum Likelihood (DFREML) algorithm was used with single trait and two traits animal models to estimate the variance and covariance components and thus, heritabilities and phenotypic, genetic and environmental correlations among nine different body measurements and weights of Brahman cattle raised in Mexico. The following measurements were considered: hip width, pin width, hip‐pin width, anterior height, posterior height, body length, thorax perimeter, scrotal circumference and weight. The analysis was based on a total of 1018 animals, born between 1992 and 1995, from 17 herds in the Mexican States of Chiapas, San Luis Potosi, Tabasco, Tamaulipas and Veracruz. The model included the following fixed effects: herd, year‐season of birth, sex, age of the animal and feed management. The only random effect was the direct additive genetic contribution of each animal. All fixed effects in the model were significant for all traits (p < 0.05). Estimated heritabilities for the traits were: hip width 0.57, pin width 0.32, hip‐pin width 0.41, anterior height 0.56, posterior height 0.54, body length 0.32, thorax perimeter 0.49, scrotal circumference 0.02 and weight 0.66. The magnitude of the heritabilities was medium to high, with the exception of scrotal circumference. The genetic correlations among all body measurements were consistently positive and high, ranging from 0.64 to 1.00. Although other measures showed higher genetic correlations with weight, thorax perimeter combines a high value (0.70) with ease and repeatability, making it a useful field measurement to estimate body weight when scales are not available.     

Ultrastructural Study of the Canine Zona Pellucida Surface During In Vitro Maturation

The aim of the present study was to compare the ultrastructure of the surface of the zona pellucida (ZP) of immature and in vitro matured dog oocytes using scanning electron microscopy (SEM). Bitch oocytes were collected after ovariohysterectomy; the ovaries were sliced and the released cumulus–oocyte complexes (COCs) were washed with phosphate buffered saline (PBS). The selected COCs were randomly allocated into three groups, two groups were processed after in vitro maturation at both 72 and 96 h and a third group was processed immediately at immature state in PBS medium. After that, oocytes were fixed, critical point dried and viewed by using SEM. The diameters of the outer holes of the ZP were measured on a total of 93 oocytes; the results were analyzed with anova . The mean diameters of holes were different between groups (p < 0.05): 0.69 ± 0.12, 1.56 ± 0.19 and 1.42 ± 0.27 μm, for immature and in vitro matured oocytes for 72 and 96 h, respectively. The difference in the hole sizes between immature and in vitro matured canine oocytes indicates that the ZP surface is related to oocyte maturity in canines.     

The effects of antigenic competition on the efficacy of multivalent footrot vaccines

SUMMARY A multivalent footrot vaccine has been developed, containing pilus antigens produced in recombinant Pseudomonas aeruginosa and representing all nine serogroups of Dichelobacter (Bacteroides) nodosus commonly recognised in the field. The responses of sheep to the multivalent vaccine have been compared with those to monovalent vaccines representing only a single serogroup. Antigenie competition between serogroups occurred in sheep immunised with the multivalent formulation, but high levels of protection were still achieved. The study showed that in multivalent footrot vaccines, antigenic competition is predominantly due to the presence of a family of immunologically-related pilus antigens rather than to interference by extraneous proteins.     

Bulk milk urea concentrations and their relationship with cow fertility in grazing dairy herds in southern Chile

Milk urea determination is being used as a broad indicator of protein/energy imbalance in dairy herds. The main purpose of this study was to compare blood and bulk milk urea values in grazing herds, to evaluate their seasonal variation under South Chilean conditions, and to examine their potential relationships with herd fertility. The association between herd blood urea concentration (mean of seven lactating cows) and bulk milk urea concentration (tank containing milk from the previous 24 h) was determined in 21 diary herds. Reference values, seasonal and herd variance, and the frequency of herds with values outside a range of 2.5 to 7.3 mmol/l were determined in bulk milk samples obtained monthly for a period of one year from 82 suppliers at two creameries located in southern Chile. Finally, bulk milk urea was measured every two weeks in samples from 24 herds, and the first service conception rate (FSCR) from 2153 dairy cows was determined. Mean bulk urea concentration was highly correlated with mean herd blood urea concentration (r = 0.95; p < 0.01). Mean urea concentration in the bulk milk samples obtained during one year from 82 herds was 4.9 +/- 1.2 mmol/l, with a range of 1.5 to 11.6 mmol/l. The highest values were found during spring and the lowest values during the summer. There was a high seasonal variation (CV = 13-47%) and between-herd variation (CV = 20-31%). Out of a total of 984 samples, 5.4% had urea values > 7.3 mmol/l and 3.8% had values < 2.5 mmol/l. Of the 82 herds, 27% had values outside the reference interval (2.5-7.3 mmol/l) on two or more occasions. FSCR was lower in herds when the bulk milk urea was > 7.3 mmol/l (50.7%) than in cows, where the urea concentration was < 5.0 mmol/l (73.8%) at the time of insemination. The study concluded that bulk milk urea concentrations provided information similar to herd blood urea concentrations in local grazing dairy herds. There was a high frequency of herds with abnormal values, with large variations between herds and between seasons. Increased milk urea concentrations during spring were associated with lower conception rates.     

Decomposition of cattle dung on grazed signalgrass (Brachiaria decumbens Stapf) pastures in monoculture or intercropped with tree legumes

Livestock excreta is one of the major nutrient sources in natural grasslands. Understanding how livestock diet and season affects the decomposition dynamics is critical to nutrient cycling models. We hypothesised that livestock diet and season of the year affect dung decomposition. This study evaluated the decomposition and release of N, P, K, Ca, Mg, and Na from faeces of cattle collected in dry and wet seasons. Treatments were signalgrass (Brachiaria decumbens Stapf) in monoculture or mixed with sabiá (Mimosa caesalpiniifolia Benth.) or gliricidia (Gliricidia sepium (Jacq.) Kunth ex Walp.). Excreta samples were incubated in nylon bags for 0, 2, 4, 8, 16, 32, 64, 128 and 256 d. The single negative exponential mathematical model was adequate (P < 0.0001) to explain the decomposition. The relative rate of dung decomposition (k) was greater for samples that originated from cattle grazed on signalgrass (k = 0.00284 g g^?1 d^?1), followed by sabiá (k = 0.00233 g g^?1 d^?1), and gliricidia (k = 0.00200 g g^?1 d^?1) pastures. The rate of nutrient release showed a time effect for all variables and interaction between time and season for Ca (P = 0.0042) and Mg (P = 0.0013). Faeces collected from cattle grazing/browsing intercropped pastures tended to have lower decomposition rates.