Replacement of fishmeal by vegetable meal mix in the diets of Litopenaeus vannamei reared in low‐salinity biofloc system: effect on digestive enzymatic activity

Biofloc (consortium of diverse microorganisms associated to suspending substrates) was developed from waste of shrimp Litopenaeus vannamei postlarvae culture under low salinity (5 g L^?1) to provide an additional nutritious biomass and reduce fishmeal inclusion in feeds in a 28‐day indoor shrimp nursery trial conducted in 15 experimental containers (250 L stocked at 600 org m^?3). Four experimental diets (isoproteic and isocaloric) containing different percentage of fishmeal: 0%, 10%, 20% and 30% substituted by vegetable meal mix (corn, sorghum and wheat) were formulated and elaborated. A control treatment consisted of a commercial feed. The main water quality parameters were monitored, and no significant differences were found among treatments. The growth and survival were similar among treatments. In general, digestive enzymatic activities showed differences being greater in the biofloc system compared with clear water. It was concluded that low‐salinity shrimp nursery could be successfully developed with minimum inclusion of fishmeal in feeds, without significant effect on production response. The adjustment of C : N ratio allowed the increase of microbial biomass in the bioflocs, which contributed to maintain good water quality, provide live food and enhance digestive enzymatic activity of cultured organisms.     

Optimizing Salting and Smoking of Catfish (Bagre marinus) Using Response Surface Methodology

ABSTRACT

Response surface methodology was used to assess the effects of brine concentration (0.1127–0.2473 g NaCl/g), salting time (49–271 min), smoking temperature (53.2–86.8°C), and smoking time (216–384 min) on moisture content, salt content, yield, taste preference, and texture preference of smoked catfish slices. Optimal process conditions were determined through the graphical method and desirability function approach. The desirability function showed that the optimal conditions for salting and smoking of catfish were: smoking temperature, 70°C; smoking time, 300 min; salting time, varying from 193.39 to 194.68 min; and brine concentration varying from 0.1791 to 0.1797 g NaCl/g. Under optimal conditions, moisture content, salt content, yield, taste preference, and texture preference of smoked catfish were 0.53 g water/g, 0.064 g NaCl/g, 58%, 3.7, and 3.7, respectively.     

Effect of Daily Food Supplementation with Essential Fatty Acids on Canine Semen Quality

Polyunsaturated fatty acids are important membrane components that influence membrane integrity and fluidity. In the present study, the effect of oral supplementation for 60 days with essential fatty acids (omega 3, 6 and 9) and vitamin E on canine semen quality was evaluated. Sixteen dogs were selected for the experiment; eight were used as the control group and eight received the fatty acid supplemented diet for 60 days. Semen samples were taken every 15 days during the entire experimental period and were analyzed for volume (ml), motility (%), vigour (0–5), concentration (×10⁶/ml), morphology of spermatozoa (%), plasma membrane integrity (%; using the hyposmotic swelling test) and thermoresistance (motility and vigour after 4 h at 38°C). We concluded that, daily supplementation with omega 3, omega 6 and omega 9 fatty acids, together with vitamin E, for a period of 60 days, significantly increased the semen volume of the treated group after 15 days of supplementation; the vigour and concentration of spermatozoa were superior after the first month of supplementation, while the percentage of morphologically abnormal spermatozoa decreased and the cells were protected against thermal stress.     

Comparison of Two Doses of the GnRH Antagonist, Acyline, for Pregnancy Termination in Bitches

Gonadotropin-releasing hormone (GnRH) antagonists are particularly useful when a rapid inhibitory effect on the gonadal axis is required. The aim of this study was to test the efficacy and clinical safety of a low and high dose of the third generation GnRH antagonist, acyline, on pregnancy termination in female dogs. The effect of the antagonist on the progesterone (P₄) serum concentration was also described. Twenty-one mid-pregnant bitches were randomly assigned to a single subcutaneous (SC) dose of a placebo (PLACE; n = 7), a low (ACY-L; 110 μg/kg; n = 6) or high (ACY-H; 330 μg/kg; n = 8) dose of acyline. The animals were followed up for 15 days. All ACY treated but no placebo-treated animals terminated their pregnancy by abortion (p < 0.01). The ACY-L and ACY-H groups interrupted their pregnancy 7 ± 1.9 and 6.4 ± 1.3   days after treatment, respectively (p = 0.7). A significant interaction between treatment and day was found (p < 0.01) for P₄ serum concentrations when PLACE was compared with both ACY groups. No difference was found for this hormone between both ACY groups (p > 0.05) where P₄ diminished throughout the study. The decreasing rate varied among animals and was closely related to the time of abortion when P₄ reached basal concentrations. In PLACE animals, gestation progressed normally and P₄ did not change throughout the study (p > 0.05). None of the bitches presented side effects. It was concluded that acyline safely terminated mid-pregnancy by permanently decreasing P₄ serum concentrations.     

Effect of beta‐aminoproprionitrile on eggshell formation

1. Eggshells are bioceramic‐biopolymer composites made by a cell‐mediated deposition of an extracellular matrix which drives the organisation of the inorganic phase. Ultrastructurally, eggshells are composed of shell membranes, mammillary knobs, palisade, and cuticle. Shell membranes are two nets of type X collagen‐containing fibrils. On to these membranes, the mammillary knobs, that is, the crystal nucleation sites, are deposited. Type X collagen is highly cross‐linked and insoluble.

2. In order to evaluate the role of type X collagen cross‐linking on eggshell formation, hens were injected with different doses of β‐aminoproprionitrile, which specifically interferes with cross‐link formation.

3. Changes in egg size and shape were observed. Scanning electron micrographs analysis of these eggs demonstrated marked changes in crystal growth and shell membrane structure and arrangement. A dot‐blot analysis, using a monoclonal antibody against chicken type X collagen, shows a dose‐dependent increase in shell membrane collagen extractability.

4. It is concluded that the formation of β‐aminoproprionitrile‐sensitive cross‐links among the type X collagen molecules of the shell membranes play an essential role in normal eggshell formation.     

Cytokine mRNA expression and pathological findings in pigs inoculated with African swine fever virus (E-70) deleted on A238L

African swine fever virus (ASFV) induces a variety of immune responses and clinical forms in domestic pigs. As it is the only member of the Asfarviridae family, ASFV encodes many novel genes not encoded by other virus families. Among these genes, A238L may regulate the synthesis of pro-inflammatory cytokines, controlled mainly by NFkappaB and NFAT pathways. In this study, we inoculated two groups of pigs, one with the ASFV highly virulent E-70 isolate, deleted on A238L gene, and the other group with the parental E-70 isolate. No significant differences were observed in the clinical signs or pathology between both groups. However, the TNF-alpha mRNA expression was strongly enhanced in the PBMC from pigs inoculated with the virus deleted in A238L, reinforcing the role of the A238L gene in the inhibition of the NFkappaB pathway of expression of cytokines. No up-regulation of pro-inflammatory cytokines was observed in the PBMC of animals inoculated with the E-70 isolate, even though apoptosis and haemorrhages were evident and might be related to the presence of bystander monocyte-macrophages expressing these cytokines. Other studies using ASFV deleted in other genes inoculated in the natural hosts should be performed to gain further insight into the role of these genes in the pathogenesis of ASF.     

Energy Metabolism and Leptin: Effects on Neuroendocrine Regulation of Reproduction in the Gilt and Sow

It is well established that reproductive function is metabolically gated. However, the mechanisms whereby energy stores and metabolic cues influence appetite, energy homeostasis and fertility are yet to be completely understood. Adipose tissue is no longer considered as only a depot to store excess energy. Recent findings have identified numerous genes, several neurotrophic factors, interleukins, insulin-like growth factor binding protein-5, ciliary neurotrophic factor and neuropeptide Y (NPY) as being expressed by adipose tissue during pubertal development. These studies demonstrated for the first time the expression of several major adipokines or cytokines in pig adipose tissue which may influence local and central metabolism and growth. Leptin appears to be the primary metabolic signal and is part of the adipose tissue-hypothalamic regulatory loop in the control of appetite, energy homeostasis and luteinizing hormone (LH) secretion. Leptin's actions on appetite regulation are mediated by inhibition of hypothalamic NPY and stimulation of proopiomelanocortin. Its effects on gonadotropin-releasing hormone (GnRH)/LH secretion are mediated by NPY and kisspeptin. Thus, leptin appears to be an important link between metabolic status, the neuroendocrine axis and subsequent fertility in the gilt and sow.     

Effects of Growth Hormone on In Situ Culture of Bovine Preantral Follicles are Dose Dependent

The objective of this study was to evaluate different concentrations of growth hormone (GH) on the development of bovine preantral follicles cultured included in the ovarian tissue (in situ) on the rates of morphologically normal, viable, primordial and developing follicles, as well as the oocyte and follicle diameter and ultrastructural analysis. Ovarian fragments collected from cows with no cross‐breeds defined were cultured in situ for 1 and 7 days in minimal essential medium (α‐MEM+) supplemented with different concentrations of recombinant human GH (0, 10, 25, 50 ng/ml). The ovarian fragments non‐cultured (control) and cultured were processed for classic histology, mechanical isolation and electron transmission microscopy (MET). The parameters underwent anova (Tukey′s and Dunnett′s tests) and chi‐square test (χ²). After 7 days of culture, the treatment with 50 ng/ml GH showed no differences with fresh control (p > 0.05) and had greater effectiveness than in the 0, 10 and 25 ng/ml GH concentrations of the morphologically normal follicles. Regarding the primordial follicles, a reduction was observed in the 50 ng/ml GH concentration concomitant with the significant increase in developing follicles, differing from both the fresh control and the other GH concentrations tested. In addition, 50 ng/ml GH showed a larger follicle and oocyte diameter when compared to the other treatments cultured. Similar structures were ultrastructurally observed in the control group, 50 ng/ml GH. Follicles cultured in 10 ng/ml GH showed nuclear invagination, vacuoles and lesioned basal membrane. Hence, it is concluded that 50 ng/ml GH is the most effective concentration for the development of preantral follicles cultured in situ.     

Molecular evolution of herbicide resistance to phytoene desaturase inhibitors in Hydrilla verticillata and its potential use to generate herbicide-resistant crops

Hydrilla [Hydrilla verticillata (Lf) Royle] is one of the most serious invasive aquatic weed problems in the USA. This plant possesses numerous mechanisms of vegetative reproduction that enable it to spread very rapidly. Management of this weed has been achieved by the systemic treatment of water bodies with the herbicide fluridone. At least three dioecious fluridone-resistant biotypes of hydrilla with two- to fivefold higher resistance to the herbicide than the wild-type have been identified. Resistance is the result of one of three independent somatic mutations at the arginine 304 codon of the gene encoding phytoene desaturase, the molecular target site of fluridone. The specific activities of the three purified phytoene desaturase variants are similar to the wild-type enzyme. The appearance of these herbicide-resistant biotypes may jeopardize the ability to control the spread of this non-indigenous species to other water bodies in the southern USA. The objective of this paper is to provide general information about the biology and physiology of this aquatic weed in relation to its recent development of resistance to the herbicide fluridone, and to discuss how this discovery might lead to a new generation of herbicide-resistant crops.