The site of action of crossability genes (Kr 1, Kr 2) between Triticum and Secale. II. Proportion of pistils containing pollen tubes and effects of alternate pollination on seed set

Summary Different wheat genotypes (T. aestivum) were crossed with rye to ascertain the site or sites of manifestation of the crossability genes, Kr ₁ and Kr ₂. By using fluorescence microscopy, it was found that the order of increasing proportion of wheat micropyles containing pollen tubes is strongly correlated with the levels of crossability with rye. High crossable genotypes have more micropyles containing pollen tubes than those of the low crossable ones. Most of the inhibition or retardation of pollen tubes occurred between the style base and top of the embryo sac, expecially with the low crossable genotypes where both Kr-genes are present. The results also indicate that Kr ₁ is a greater inhibitor than Kr ₂. Seed set is also highly correlated with the number or proportion of micropyles having pollen tubes. Alternate pollinations seem to support the view that rye pollen tubes do not reach the micropyles of the low crossable genotypes, and hence when repollinated with wheat selfed seeds are produced.     

Growth and reproductive performance of broodstock shrimp reared in a biosecure recirculating aquaculture system versus a flow-through pond

Over the past decade, viral pathogens have caused mass mortalities of farmed shrimp throughout the major shrimp farming regions of the world. In addition, the global shrimp farming industry has been criticized for negatively impacting coastal environments. These issues have raised concerns about the sustainability of traditional shrimp farming practices, and have prompted farmers and researchers to develop biosecure technologies that promote a sustainable industry. Current technologies include the use of specific pathogen free (SPF) shrimp that are grown to market size in recirculating systems that rely on pathogen exclusion. Inherent in this approach is the need to produce SPF broodstock under biosecure conditions. However, there is a paucity of information on broodstock growth and reproductive performance when they are reared in recirculating systems. The present investigation compares shrimp growth and reproductive performance in two trials where shrimp were cultured from market size (20 g) to broodstock size (40–60 g) in a recirculating aquaculture system (RAS) versus a flow-through earthen pond (EP). In trial 1, mean growth rates of males and females in the RAS were 0.83 and 1.33 g/week, respectively. In the EP, males and females grew 1.07 and 1.48 g/week, respectively. In trial 2, mean growth rates of males and females in the RAS were 0.90 and 1.53 g/week, respectively, whereas in the EP, males and females grew and 1.24 and 1.78 g/week. Slower growth rates in the RAS may be attributed to the lack of natural productivity, which provides supplemental nutrition to the shrimp. In addition to growth rates, reproductive performance of broodstock reared in the RAS was compared with historical reproductive performance of broodstock reared in the EP. Data on spawning success and production of viable nauplii revealed no significant differences (P>0.05) between broodstock shrimp reared in these two systems. These results indicate that broodstock shrimp can be cultured in a biosecure RAS while maintaining good growth and high survival. In addition, reproductive performance of broodstock shrimp reared in a RAS is not compromised when compared with broodstock shrimp reared in a conventional, flow-through pond.     

Development of a specific pathogen free population of the Chinese fleshy prawn, Fenneropenaeus chinensis: Part II. Secondary quarantine

The Oceanic Institute (OI), in collaboration with researchers from the University of Arizona (UAZ), established a population of specific pathogen free (SPF) Fenneropenaeus chinensis through Secondary Quarantine (SQ) in Kona, Hawaii. Shrimp were 0.38 g (S.D. ± 0.13 g) when they entered the nursery/growout module of the SQ facility. Juveniles from five maternal families were stocked in separate 230-L nursery tanks, as was a sixth family comprised of shrimp from two of the seven original spawns. After tagging, representative shrimp from all six families were stocked in a 50-m² concrete raceway that was enclosed in a biosecure greenhouse. After 155 days in the growout module, mean shrimp weight was 23.4 g (S.D. ± 7.25 g) and females (29.1 ± 4.61 g) were 74% larger than males (16.7 ± 2.44 g). A Sprung Structure™ was erected to enclose the biosecure maturation and hatchery module of the SQ facility. Broodstock were subjected to an acclimation process where they were kept in seawater at 22 °C, followed by a reduction in water temperature of 1 °C/day until the temperature reached 17 °C. At this time, unilateral eyestalk ablation was performed on female broodstock and water temperature was further reduced at the same rate until it reached 12 °C. After 2 weeks, water temperature was raised to 17 °C at a rate of 1 °C/day to induce ovarian development. Production of an F₁ generation of Fe. chinensis was successfully accomplished using artificial insemination, and representative shrimp from this generation have tested negative for all specifically listed pathogens using histology and PCR/RT-PCR. Of particular interest with Fe. chinensis is their cold tolerance. This species may represent a valuable resource for shrimp farmers in temperate and sub-tropical climates to grow a second “winter” crop, thereby increasing production and profitability for the shrimp farmer.     

Effect of induction dose, lactation stage and body condition on tiletamine-zolazepam anaesthesia in adult female grey seals (Halichoerus grypus) under field conditions

Tiletamine-zolazepam (TZ) was used at a mean (sd) dose of 1.18 (0.15) mg/kg administered intramuscularly to anaesthetise adult female grey seals (Halichoerus grypus) under field conditions at three different stages during their lactation period. A significant correlation was observed between the induction dose and time to induction (r=-0.582, P=0.011). Stage of lactation had a significant effect on condition index (CI), calculated as axial girth divided by length (P<0.001), and time to induction (P=0.009). No effect of CI on induction or recovery time was demonstrated. Respiratory rate decreased during induction and increased significantly (P<0.001) during surgical biopsy of blubber. Recovery occurred after 32.5 (11.9) minutes. Minor complications (tremor, vocalisation and mild dyspnoea) were observed in a small number of cases, none of which required treatment.     

Feline bacterial urinary tract infections: An update on an evolving clinical problem

Although feline urine is increasingly submitted for bacterial culture and susceptibility testing as part of a more general diagnostic work-up for a range of presentations in veterinary practice, bacterial urinary tract infections (UTIs) are relatively uncommon due to a variety of physical and immunological barriers to infection. Culture positive urine is most often obtained from older female cats and the clinical history may include hematuria, dysuria and pollakiuria, or the infection may be occult. Urinalysis usually reveals hematuria and pyuria, and Escherichia coli and Gram-positive cocci are cultured most frequently. Most feline UTIs can be successfully treated using oral amoxicillin or amoxicillin/clavulanic acid administered for at least 14 days, but the prevalence of antimicrobial resistance amongst infecting bacterial species is a growing concern. There is currently no conclusive information on the safety and efficacy of alternative therapeutic agents for the treatment of feline UTIs.     

Serum chlortetracycline concentrations in parrots fed medicated seed diets

Various seed diets containing chlortetracycline were fed to large and small parrots to evaluate serum chlortetracycline concentrations. The substitution of dehulled sunflower seed for whole sunflower in the seed mix may have resulted in higher chlortetracycline concentrations in cockatoos and parrots. The serum chlortetracycline concentration achieved for all diets was less than the goal of 1 μg/mL, but the concentrations attained may be useful for therapy.     

Effects of Diet and Water Source on the Nursery Production of Pacific White Shrimp Litopenaeus vannamei

Penaeid shrimp reared in eutrophic pond water grow significantly faster than shrimp in clear well water, and this growth enhancement is especially pronounced in postlarval shrimp. The objective of this study was to determine if the nutritional benefits of pond water could supplement a lower protein feed for postlarval Pacific white shrimp Litopenaeus vannamei . Sixteen 230-L tanks were stocked with 10-d postlarvae at a density of 350 shrimp/tank. Four treatments (four replicates/treatment) were tested for 6 wk and consisted of: 1) shrimp grown in well water and fed a commercially available 45%-protein feed (W/45); 2) shrimp grown in pond water and fed the same 45%-protein feed (P/45); 3) shrimp grown in well water and fed a commercially available 52%-protein feed (W/ 52); and 4) shrimp grown in pond water and fed the same 52%-protein feed (P/52). At the end of the experiment. mean weight gain (± SE) for shrimp in pond water (1.85 ± 0.03 g) was significantly greater ( P > 0.0001) than shrimp in well water (0.98 ± 0.10 g). Mean weight gain for shrimp fed the 52%-protein feed (1.56 ± 0.13 g) was significantly greater ( P > 0.0001) than shrimp fed the 45%-protein feed (1.26 ± 0.20 g). In addition, there was a significant interaction effect between water source and feed ( P > 0.0001). Mean weight gain for shrimp in the W/52 treatment (1.23 ± 0.04 g) was 68% greater than shrimp in the W/45 treatment (0.73 ± 0.03 g). However, mean weight gain for shrimp in the P/52 treatment (1.90 ± 0.03 g) was only 5% greater than shrimp in the P/45 treatment (1.80 ± 0.04 g). These results suggest that organically rich pond water provides postlarval shrimp with sufficient nutrients to compensate for nutritional deficiencies associated with a lower protein feed.