Economic costs of recorded reasons for cow mortality and culling in a pasture-based dairy industry.

The objective of this study was to determine the economic costs associated with different reasons for cow culling or on-farm mortality in a pasture-based seasonal system. A bioeconomic model was developed to quantify costs associated with the different farmer-recorded reasons and timing of cow wastage. The model accounted for the parity and stage of lactation at which the cows were removed as well as the consequent effect on the replacement rate and average age structure of the herd. The costs and benefits associated with the change were quantified, including animal replacement cost, cull salvage value, milk production loss, and the profitability of altered genetic merit based on industry genetic trends for each parity. The total cost of cow wastage was estimated to be NZ$23,628/100 cows per year (NZ$1 = US$0.69) in a pasture-based system. Of this total cost, NZ$14,300/100 cows worth of removals were for nonpregnancy and unknown reasons, and another NZ$3,631/100 cows was attributed to low milk production, mastitis, and udder problems. The total cost for cow removals due to farmer-recorded biological reasons (excluding unknown, production, and management-related causes) was estimated to be NZ$13,632/100 cows per year. Of this cost, an estimated NZ$10,286/100 cows was attributed to nonpregnancy, mastitis, udder problems, calving trouble, and injury or accident. There is a strong economic case for the pasture-based dairy industries to invest in genetic, herd health, and production management research focused on reducing animal wastage due to reproductive failure, mastitis, udder problems, injuries or accidents, and calving difficulties.

Wound healing and the Shaw scalpel.

The Shaw heated scalpel is now widely used in head and neck surgery because it provides better hemostasis intraoperatively. Concerns persist over the immediate and long-term effects of this instrument on wound healing. This study compares heated and unheated Shaw scalpel incisions in the skin of 7-week-old piglets. Tensile strength measurements and histologic evaluations were made at frequent intervals up to nine weeks after incision. Histologic studies showed no differences in the two groups at any time in the study. Tensile strength of wounds was significantly less two weeks after incision in the Shaw scalpel group, but following that time, the wounds increased in strength, and by seven weeks, the two groups were equal in this respect. Thus, we conclude that the Shaw scalpel wounds in pigs are, ultimately, similar to standard scalpel wounds, although there is a period of diminished tensile strength.

Factors effective in reducing rat mortality due to acute liver failure as induced by D-galactosamine poisoning.

Mortality from D-galactosamine hydrochloride (D-GalN)-induced acute liver failure (ALF) in rats can be reduced by (1) transplanting intact hepatocytes; (2) injecting cytosol from fractionated hepatocytes dispersed from a liver subjected to 70% hepatectomy 24 hr earlier (CYT-H); (3) injecting a cell-free supernate derived from cultured hepatocytes (SUP); or (4) injecting neuraminidase-treated plasma where the plasma is drawn 24 hr after donor rats are subjected to 70% hepatectomy (PHP-neu). These treatments are effective when administered 20-24 hr after D-GalN poisoning, but experiments to determine the alterations in mortality rates as a function of time of treatment in relation to poisoning have not been performed. Two experiments are reported here. In the first the survival of lethally poisoned rats was compared after intravenously injecting either SUP prepared from cultured hepatocytes of syngeneic adult or fetal rat sources, or CYT-H from syngeneic adult rats 20 hr after poisoning. Untreated rats, rats treated with culture media alone, or rats treated with CYT from a nonregenerating source had an 88-100% mortality, with all deaths occurring within 72 hr following poisoning. Improved survival followed all other treatments: 55% of the rats receiving adult SUP, 70% of the rats receiving fetal SUP, and 80% of the rats receiving CYT-H survived. In the second experiment the survival of poisoned rats was compared after injecting them with PHP-neu, PHP not treated with neuraminidase (PHP without neu), and neuraminidase-treated plasma from sham-operated rats (SP-neu) or normal, nonoperated rats (NP-neu) 20 hr after poisoning.(ABSTRACT TRUNCATED AT 250 WORDS)

Polycrystalline echinoderm calcite and its fracture mechanics.

Polycrystalline calcite was revealed by scanning electron microscopy of fractured skeletal ossicles of the sea star Echinaster spinulosus (Echinodermata, Asteroidea). Whisker-like calcite crystals were observed in specimens that were loaded in stress relaxation before being fractured; rapidly broken surfaces were smooth and glassy. The crystallites were 1300 angstroms wide and at least 3600 angstroms long and were packed together in lamellae. The lamellae were wound into spirals that formed the trabecular bars. All the crystallites in an ossicle appear to be aligned in the same direction. Geometric considerations indicate that the requirement for packing the crystallites smoothly may explain the high magnesium ion concentration of echinoderm calcite.