Effects of Stocking Sac-Fry and Hatchery-Fed Fry on Production of Fingerling Channel Catfish Ictalurus punctatus

Abstract.— Channel catfish Ictalurus punctatus fry are typically held under hatchery conditions for 7 to 14 d after hatching to allow feeding and growth before they are stocked into nursery ponds to produce fingerling catfish. In an attempt to reduce hatchery operating costs, several catfish fingerling producers in Louisiana presently stock fry within 2 d after hatching before yolk absorption is complete. Fry at this stage of development are commonly referred to as "sac-fry." Although research has shown that fry can be stocked at the onset of yolk absorption with no detrimental effects on subsequent fingerling production, stocking sac-fry has been reported to result in reduced fingerling survival. To further investigate this topic, production trials were conducted in experimental outdoor pools over the course of two growing seasons to evaluate the effect of stocking fry of three different ages (2-, 7-, and 14-d post-hatch, DPH) on survival, growth (weight and length), condition factor (K), yield, feed consumption, and feed conversion ratio (FCR) of fingerling catfish. Results from both trials indicated that the age at which fry were stocked had no effect on production characteristics with the exception of growth. Specifically, fingerlings reared from fry stocked at 2 and 7 DPH were significantly larger than fingerlings reared from fry stocked at an age of 14 DPH. These findings suggest that the practice of stocking sac-fry may be a suitable alternative to the traditional procedure of holding and feeding fry under hatchery conditions prior to stocking. However, in order to fully evaluate the effects of early-age stocking of catfish fry on fingerling production, additional studies must be conducted under pond conditions. Furthermore, these studies must be coupled with a rigorous economic analysis before the practice of stocking sac-fry can be recommended to the catfish industry.     

A review of factors influencing litter size in Irish sows

Many factors influence litter size. These include genetics, gilt management, lactation length, parity distribution, disease, stress and boar fertility. In the past 20 years, litter size in Irish sows has increased by only one pig. Born alive figures now average at 11.2 pigs per litter. In this regard, Ireland is falling behind our European competitors who have made significant advances over this time. Denmark, for example, has an average figure of 12.7 pigs born alive per litter and France an average of 12.5. The single area that could be improved immediately is sow feeding. It is important that sows are fed correctly throughout pregnancy. If over-fed during pregnancy, sows will have depressed appetite during lactation. If underfed in pregnancy, sows will be too thin at farrowing. The correct way to feed a pregnant sow is to match her feed allocation to her requirement for maintenance, body growth and growth of her developing foetuses. During lactation, sows should be given as much feed as they can eat to prevent excessive loss of body condition. Liquid-feed curves should be such that lactating sows are provided with a minimum mean daily feed supply of 6.2 kg. A small proportion of sows will eat more and this could be given as supplementary dry feed. Where dry feeding is practised in the farrowing house, it is difficult to hand-feed sows to match their appetite. Ideally ad libitum wet/dry feeders should be used. From weaning to service, sows should once again be fed ad libitum. If liquid feeding, this means giving at least 60 MJ DE (digestible energy) per day during this period. If dry feeding, at least 4 kg of lactation diet should be fed daily. The effort spent perfecting sow feeding management on units should yield high dividends in the form of increased pigs born alive per litter.     

Atrioventricular valvular insufficiency and congestive heart failure in a carpet python

Right atrioventricular valve insufficiency and bilateral congestive heart failure were identified in a carpet python (Morelia spilota variegata) with the aid of colour Doppler echocardiography, electrocardiography and radiography. The snake failed to respond to diuretic therapy and was euthanased. Based on this case, it appears that bilateral congestive failure is feasible in univentricular animals with lesions restricted to one side of the heart. Loop diuretic therapy may be inappropriate in non-crocodilian reptiles because reptiles lack a loop of Henle.     

The potential environmental impact of pesticides removed from sprayers during cleaning

BACKGROUND: There is concern that pesticide residues on the external surfaces of sprayers could have an adverse impact on the environment if they are washed off, yet there is a need to remove these residues for health reasons. The aim of this study was to quantify pesticide residues contained in washings from cleaning discrete parts of a sprayer and to assess their likely environmental impact. RESULTS: The boom/rear of the sprayer and the spray tank accounted for 80% of the total pesticide load in the washings. Predicted environmental pesticide concentrations from sprayer washings were lower than predictions from the FOCUS surface water model for pesticides used under normal agricultural conditions, although for tebuconazole this difference was smaller than for the other compounds investigated. The field area over which the residues may need to be uniformly deposited to avoid overdosing during infield cleaning was typically less than 0.5 m(2), with a maximum value of 4 m(2). CONCLUSIONS: It is unlikely that infield cleaning will lead to overdosing. External residues are not insignificant, so any adverse impact on the environment must be mitigated. Appropriate measures include cleaning in the field away from surface waters and other sensitive areas, and cleaning machines over bunded areas or similar.