Effects of supplemental dietary vitamin C on quality of semen from Nile tilapia (Oreochromis niloticus) breeders

The objective of this study was to evaluate the effects of vitamin C on growth and quality of semen from Oreochromis niloticus breeders. One hundred and sixty males were fed with different levels of vitamin C (0, 261, 599 and 942 mg/kg diet). The higher weight values were recorded for 599 (166 g) and 942 (175 g) mg of vitamin C/kg diet. Sperm motility, vigour and concentration were higher with 599 and 942 mg of vitamin C/kg diet. The semen volume, gonadosomatic index and plasma protein data from the last week showed a direct relationship with increasing levels of vitamin C. No changes were observed in the hepatosomatic index and blood glucose. The haematocrit and erythrocyte showed higher values estimated by equations derived at 850 and 638 mg vitamin C/kg diet, respectively. The leucocytes were inversely proportional to the increasing levels of vitamin C. After 100 days of feeding, animals fed the diet containing 942 mg vitamin C/kg diet had higher sperm motility, linearity, curvilinear velocity, straight line velocity and average path velocity (p < .05). Higher values of beat cross‐frequency were observed in broodfish fed diets containing 942 and 599 mg vitamin C/kg. The different vitamin C levels did not cause differences in straightness, lateral head displacement and sperm morphology. For Nile tilapia males on intensive rearing and handling conditions, vitamin C levels between 599 and 942 mg/kg may be used for a better performance and quality of semen.     

Chemical Activation with a Combination of Ionomycin and Dehydroleucodine for Production of Parthenogenetic,ICSI and Cloned Bovine Embryos

The aim of this study was to evaluate the potential of dehydroleucodine (DhL), a new drug isolated from a medicinal herb used in Argentina, for activation of bovine oocyte. Several DhL concentrations and exposure times after ionomycin (Io) treatment were tested. The optimal DhL treatment, found for parthenogenetic development, was employed to produce bovine embryos by intracytoplasmic sperm injection (ICSI) and somatic cell nuclear transfer (SCNT). The best parthenogenic embryo developments were observed with 5 μm Io for 4 min followed by 5 μm DhL concentration and after 3‐h exposure time (52.3% cleavage; 17.4% morulae; 7.3% blastocyst; n = 109). This treatment generated no significant differences with standard Io plus 6‐dimethylaminopurine (DMAP) treatment in preimplantation embryo development. In our conditions, the embryo development reached after ICSI and SCNT assisted by the DhL treatment did not differ in terms of cleavage and blastocyst development from activation with standard Io plus DMAP treatment (p > 0.05). In conclusion, DhL utilization to activate oocytes and induce development of parthenogenotes, ICSI‐embryos or SCNT‐embryos is reported here for first time.     

Efficacy of partially hydrolyzed corn syrup solids as a replacement for lactose in manufactured liquid diets for neonatal pigs

Feeding manufactured liquid diets to early-weaned pigs improves growth performance and reduces days to market weight compared with pigs receiving pelleted dry feed. Few alternative dietary ingredients are utilized in manufactured liquid diets other than byproducts of the dairy industry, especially for sources of carbohydrates. This experiment was designed to evaluate the efficacy of starch from partially hydrolyzed corn syrup solids (CSS), at two different levels of hydrolyzation, as a replacement for lactose in manufactured liquid diets. Forty-eight pigs were removed from sows at 1 d of age and randomly assigned to one of three treatments: 1) control with lactose as the carbohydrate source, 2) lactose replaced (gram for gram) with CSS (dextrose equivalent [DE]-20), and 3) lactose replaced with DE-42. In addition, 10 pigs were randomly removed from several litters to provide estimates of initial body composition and small intestinal variables. Twenty-four pigs were removed from the study on d 10 of treatment, and the remaining 24 pigs were removed on d 20 of treatment. Pigs averaged 9,845 +/- 191 g at d 20 of treatment regardless of dietary treatment (P > 0.20). No differences in ADG, ADFI, or feed efficiency were detected between treatment groups from d 0 to 20 (P > 0.19). Whole-body water, protein, lipid, and ash accretion rates were unaffected by dietary treatment from d 0 to 10 or from d 0 to 20 (P > 0.20). The replacement of lactose with CSS did not affect intestinal villi height or width, or crypt depth (P > 0.10). Pigs fed lactose tended to have greater lactase activity on d 10 than pigs fed CSS (P < 0.07). Also, pigs fed lactose tended to have lower oligosaccharidase activity than pigs fed the DE-20 diet on d 20 (P < 0.07). No other differences in lactase, maltase, or long oligosaccharidase specific activity on d 10 or 20 of treatment were detected (P > 0.12). Plasma urea nitrogen concentrations were unaffected by diet on d 10 and 20 of treatment. In addition, dry matter digestibility of the diets averaged approximately 85.6 +/- 0.8% and was unaffected by dietary treatment or day of treatment. These results suggest that partially hydrolyzed CSS can be used as a replacement for lactose in manufactured liquid diets for neonatal pigs.     

Effects of flow variation on channel and floodplain biota and habitats of the Sacramento River,California, USA

• 1. Despite progress in the development of conceptual models of river processes, the validation and application of these models to conservation may be limited by a deficit of tools for intermediate‐scale (1–100km) reaches. A model was developed to examine the effect of variation in flow on the responses of two trophic levels in a large temperate river (Sacramento River) and its seasonal floodplain (Yolo Bypass). Field data and hydrologic simulations were evaluated for three hydrologically diverse years.
• 2. The simulations showed much more hydrologic variability in the floodplain than the river, with greater total surface and shallow area, longer hydraulic residence times, and lower water velocities for the floodplain.
• 3. Chlorophyll a levels were significantly higher in the floodplain than in the river, and were negatively associated with flow. These results were consistent with longer hydraulic residence times, increased surface area of shallow water, and warmer water temperatures.
• 4. Copepods and cladoceran densities were similar in the river and its floodplain, and were mostly negatively associated with flow.
• 5. There were significantly higher densities of Diptera and terrestrial invertebrates in the floodplain than the river. Diptera densities in the floodplain were positively associated with flow.
• 6. These results provide evidence of the incremental value of floodplain habitat to the conservation of large rivers. In particular, it appears that providing river–floodplain connectivity can enhance production of lower trophic levels at relatively rapid time scales, probably benefitting secondary consumers, including Chinook salmon (Onchyrhynchus tshawytscha).

Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of Post‐Thaw Addition of Seminal Plasma on Motility,Viability and Chromatin Integrity of Cryopreserved Donkey Jack (Equus asinus) Spermatozoa

Pregnancy rates in donkeys after artificial insemination with cryopreserved semen are still low, compared to the horse species. Addition of autologous seminal plasma to frozen‐thawed semen appeared to improve pregnancy rates. The aims of this study were to evaluate (1) sperm motility and plasma membrane integrity after thawing (T0) and after one and 2 h (T1 and T2) of post‐thaw incubation in either 0% (SP0) or 70% (SP70) autologous seminal plasma and (2) sperm motility, plasma membrane integrity and DNA quality (%COMP‐αt) after thawing (T0) and after 2 and 4 h (T2 and T4) of post‐thaw incubation in either 0% (SP0), 5% (SP5) or 20% (SP20) homologous seminal plasma. In experiment 1, seminal plasma decreased total and progressive sperm motility and plasma membrane intact spermatozoa immediately after dilution and at all following time points (p < 0.05). In experiment 2, total and progressive motility did not differ between treatments immediately after dilution and between SP0 and SP5 at T2, while they were lower in both SP5 and SP20 than in SP0 at T4. Plasma membrane intact sperm cells did not differ between SP0 and SP5 and were lower in SP20 at all time points. DNA quality was not affected by treatment immediately after dilution and was significantly worse for SP20 after 4 h of incubation (p < 0.05). The post‐thaw addition of seminal plasma at the tested concentrations did not improve donkey frozen semen characteristics in vitro over time.     

Viability of OPS Vitrified Sheep Embryos After Direct Transfer

The aim of this study was to evaluate the viability in the effect of open pulled straw (OPS) vitrification procedure of sheep embryos after direct transference. Embryos were produced in vivo and cryopreserved in slow freezing or OPS vitrification. The survival rates of cryopreserved embryos were compared to non-frozen standard pattern. In a first set of experiments, embryos at morula and blastocyst stages were dived in ethylene glycol (1.5 M) and frozen in an automatic freezer. After being thawed, they were directly or indirectly transferred to ewes recipient. A second group of embryos were drawn into OPS and plunged into liquid nitrogen after being exposed at room temperature for 1 min and 45 s in 10% EG plus 10% dimethyl sulphoxide (DMSO), then again for 30 s in 20% EG + 20% DMSO + 0.5 M sucrose. After being warmed, embryos were also directly transferred using a French mini straw as the catheter for the transplantation process or after in vitro dilution of cryoprotectants (two-step-process). No significant difference was observed among fresh, frozen or vitrified embryos on pregnancy rate (50.0%, 38.6% and 55.8%). However, when we evaluated only the direct transference, the pregnancy rate of OPS vitrified embryos was higher than that of frozen embryos (57.1% vs 34.8%) (p = 0.07). In addition, vitrified morulae had a higher pregnancy rate than the one with frozen embryos (64.0% vs 38.9%) (p = 0.07). Finally, our results indicate that OPS vitrification technique in association with direct transference improves the viability of sheep embryos with potential applications to field conditions.