Cholesterol requirement and phytosterols efficiency in semi‐purified diets of juvenile Pacific white shrimp Litopenaeus vannamei

Studies pertaining to cholesterol requirement are limited based on the levels evaluated and statistical analysis. Two trials were conducted to refine cholesterol requirement in Pacific white shrimp Litopenaeus vannamei feeds. The basal diet was supplemented with graded levels of cholesterol (ranging from 0.48 to 1.85 g/kg) in trial 1. Since the shrimp (initial weight: 0.24 g) growth response was very linear without reaching a plateau, it was not clear whether the requirement was met. Hence, a second trial was designed using eight diets designed with an increased range of cholesterol levels from 0.45 to 4.57 g/kg of diets. The shrimp (0.38 g initial weight) reached a final weight of (4.31–7.43 g) or per cent weight gain from 1,014%–1,874% (n = 4) after 6 weeks. Saturation kinetic model and broken‐line models with linear or quadratic ascending portions were used to evaluate dose–response relationships of feed efficiency (FE), thermal‐unit growth coefficient (TGC), whole‐body cholesterol (CHOL) and cholesterol deposition (CHOLD) against dietary cholesterol. The cholesterol requirement of shrimp was estimated at 1.9 (1.1–4.3) g/kg, 1.7 (1.1–3.4) g/kg, 2.5 (2.3–2.9) g/kg and 2.7 (2.4–3.1) g/kg of shrimp diet for FE, TGC, CHOL and CHOLD, respectively. Additionally, based on improved growth, the inclusion of phytosterol can serve as a partial replacement for cholesterol.     

Larval molting and growth of the Japanese spiny lobster Panulirus japonicus under laboratory conditions

ABSTRACT:   Ten newly hatched phyllosoma of Panulirus japonicus were cultured individually to monitor body length ( BL ) and intermolt period, and 2000 were cultured in groups to sample specimens for measurement of body weight. Phyllosoma were fed with Artemia and mussel gonad; the culture seawater temperature was 24–26°C. The individually cultured phyllosoma showed an increment in body length by the first molt of approximately 0.5 mm, and the molt increment increased to approximately 1 mm at 5 mm BL ; it was constant to 15 mm BL . Thereafter, the molt increment increased exponentially. The duration of the first instar was 6–7 days. Instar duration increased with development up to approximately 2 weeks at the 20th instar (∼16 mm BL ) and then became constant. Of the 10 larvae reared individually, five metamorphosed to the puerulus stage. The entire phyllosoma life ranged from 245–326 days (mean 289.0 days), and the number of instars ranged from 22–29 (mean 26.2). Body length in the final instar ranged from 28.50–33.10 mm (mean 30.280 mm). For the phyllosoma cultured in groups, relationships between BL and wet/dry body weights ( WW / DW , mg) were expressed as exponential equations: WW  = 0.0686 BL ^2.2023 and DW  = 0.0209 BL ^2.1905.     

Optimization of selection and mating schemes in closed broiler lines

Minimum coancestry mating (MC) is a simple mating system to reduce inbreeding in populations, in which matings are allocated so as to minimize the average inbreeding coefficient of progeny. This system was compared with random mating (RM) in simulated broiler lines. The population structure and genetic parameters were determined on the basis of an existing broiler line. Comparison of mating systems was made under two selection methods. The first method (DIS) was based on selection index for achieving desired genetic gains. In the second method (LPS), a combination of the family index and linear programming technique was applied to obtain the desired genetic gains. The selected traits were body weight at 6 weeks of both sexes and age at sexual maturity of hen. Four schemes by all the possible combinations of selection and mating methods (DIS + RM, DIS + MC, LPS + RM and LPS + MC) were compared in terms of genetic gains and inbreeding during 15 generations of selection and mating. The results obtained are summarized as follows: (i) the four schemes produced similar genetic gains averaged over replicates; (ii) the variations of genetic gains under LPS + RM and LPS + MC schemes were much smaller than under DIS + RM and DIS + MC schemes; (iii) irrespective of the selection methods, MC reduced the average inbreeding coefficients to about 80% of RM and; (iv) the inbreeding coefficients of individuals in the schemes with RM were distributed in a wide range, while the inbreeding coefficients in the schemes with MC showed a high uniformity. From these results, the LPS + MC scheme was recommended as a selection and mating strategy in closed broiler lines.     

Efficacy of atovaquone against Babesia gibsoni in vivo and in vitro

The therapeutic efficacy of atovaquone against Babesia gibsoni was examined in three dogs experimentally infected with B. gibsoni isolated from naturally infected dogs in Aomori Prefecture, Japan. Once parasitemia reached 10%, atovaquone was administered orally (30 mg/kg twice daily for 7 days). Within 2 days of atovaquone treatment, the parasite disappeared from blood smears without any clinical side effects. Anemia and thrombocytopenia were significantly improved in all the dogs. However, a polymerase chain reaction assay revealed that a B. gibsoni marker gene was intermittently present in peripheral blood after atovaquone therapy, indicating that the organism had not been eliminated, and parasites reappeared in blood smears 33 days after the last treatment. To investigate the change in sensitivity against atovaquone, an in vitro sensitivity test was performed using peripheral blood obtained from an untreated dog that was infected with the original parasite isolate, and from two of the experimentally infected and atovaquone-treated animals (blood was collected at the time of the post-treatment recurrence of the B. gibsoni infection). Atovaquone was added to the culture medium to final concentrations of 0.1, 1, 10, 100, and 1000 nM. For the untreated parasites, complete growth inhibition occurred at 1000 nM of atovaquone, whereas the recurrent parasites were inhibited by only 39.52 +/- 8.34% and 31.31 +/- 8.14% at this concentration after 48 h of incubation. Thus, the recurring parasites were less sensitive to atovaquone than the untreated originally isolated parasites.     

Contraceptive effect of a gonadotropin-releasing hormone vaccine on a captive female African Lion (Panthera leo): a case study

Lions (Panthera leo) breed well under captivity, so contraception has been commonly conducted for population management, leading to a demand for a less invasive and reversible contraceptive approach in lions. In this study, we examined the efficacy of a commercial gonadotropin-releasing hormone vaccine as a method of suppressing reproductive activity in a sexually matured female lion. Under behavioral restraint, the vaccine was injected twice (days 0 and 109). After the initial vaccination, ovarian activity is still observed. After the second vaccination, contraceptive effect was confirmed for 246 days until restart of estrous cycles. We confirmed only a slight swelling around the injection site after the second vaccination. This study may suggest an alternative option for a contraceptive method in lions.     

Effects of selenium supplementation on plasma progesterone concentrations in pregnant heifers

It is known that selenium (Se) has various functions in animals. Many investigations on the biochemical and physiological effects of Se have been previously reported; however, the detailed function of Se in reproduction is not yet clear. We proposed the possibility that Se plays a notable role in progesterone production. The aim of this study was to clarify the effects of Se supplementation on progesterone levels of pregnant Holstein heifers. Eight Holstein heifers (?Se) were fed basal diet (containing 0.022 ppm of Se) throughout the experiment. While a 0.3 ppm diet of Se (sodium selenite) was fed to another seven animals (+Se) with basal diet. Blood sampling was carried out every week. Plasma Se concentrations were higher in Se‐supplemented cows compared with controls (?Se) (P < 0.01) throughout the experiment. Se supplementation increased plasma progesterone in the 29–39 weeks of pregnancy from 4.98 ± 0.64 to 6.86 ± 0.49 ng/mL on average (P < 0.05). The present findings suggest that Se contributes to maintaining the function of the corpus luteum and/or placenta in the latter period of pregnancy.     

Analysis of glycosuria in okapi (Okapia johnstoni): Examination of urinary N‐acetyl‐β‐D‐glucosaminidase

We analyzed the urinary excretion of glucose and N‐acetyl‐β‐D‐glucosaminidase (NAG) in six okapis (Okapia johnstoni) in captivity to investigate the cause of their urinary sugar excretion. The urinary glucose‐positive okapi had significantly higher urinary NAG indices than the urinary glucose‐negative okapi. There was also a positive correlation between urinary glucose levels and urinary NAG indices. These results suggest that the proximal tubular function of the glycosuric okapi may have been obstructed, which impaired glucose reabsorption.     

Modes of antifungal action of (2E)-alkenals against Saccharomyces cerevisiae

A series of aliphatic (2E)-alkenals from C(5) to C(14) were tested for their antifungal activity against Saccharomyces cerevisiae ATCC 7754. (2E)-Undecenal (C(11)) was found to be the most effective with the minimum fungicidal concentration (MFC) of 6.25 microgram/mL, followed by (2E)-decenal (C(10)) with an MFC of 12.5 microgram/mL. The time-kill curve study showed that (2E)-undecenal was fungicidal against S. cerevisiae at any growth stage, and this activity was not influenced by pH values. The (2E)-alkenals inhibited glucose-induced acidification by inhibiting the plasma membrane H(+)-ATPase. The primary antifungal action of medium-chain (C(9)-C(12)) (2E)-alkenals against S. cerevisiae comes from their ability to function as nonionic surface-active agents (surfactants), disrupting the native membrane-associated function nonspecifically. Hence, the antifungal activity of (2E)-alkenals is mediated by biophysical processes, and the maximum activity can be obtained when the balance between the hydrophilic and hydrophobic portions becomes the most appropriate.