The objective of this study was to assess the usefulness of two common agricultural cultivations to cover exposed seeds after sowing, with the purpose of reducing the risk to birds from pesticide-treated grain. In three experimental trials, both rolling and harrowing buried a large proportion of exposed seeds after drilling or broadcasting, but their relative efficacy was affected by seedbed condition. In a fine seedbed, the proportion of seeds covered by harrowing (84–86%) was substantially higher than that for rolling (53–58%). In a rough seedbed, rolling gave slightly better results (76–84%) than harrowing (73–77%). In trials simulating seed spills, harrowing proved very effective irrespective of seedbed condition, as it dispersed most spills and buried most of the exposed seeds (85–92%). Rolling was of much less value for spills because seed coverage was lower (25–60%) and most spills remained as clumps of seeds. Estimates are presented of how reductions in surface grain by cultivations would affect an index of risk to two granivorous species of birds from fonofos, a common insecticide seed treatment. The potential of these cultivations for reducing the risk of acute bird poisoning is discussed. A decision scheme summarises recommendations on how to utilize these cultivations in different parts of the field in relation to sowing depth and seedbed condition for agronomic and environmental benefits.

This study investigated whether the risk to birds from pesticide-treated cereal seed could be reduced by increasing sowing depth and hence reducing the density of seed exposed on the soil surface. Results are presented from both commercially farmed fields and experimental field trials on light fenland soils in England. Farmers' intended sowing depth for winter wheat varied considerably (20–60mm) and often exceeded the recommended depth. The density of exposed seeds on commercial fields and in two experimental sowings was inversely related to actual sowing depth. In the experimental trials, better incorporation was achieved on a fine seedbed than on a rough seedbed drilled at similar depth. Results suggest that the manipulation of the depth of sowing provides satisfactory seed coverage in the centre of fields (mainfield) with a fine seedbed, but it is less effective in rough seedbeds and in the margins (headlands). In trials, deep sowing (46–50mm) gave better yields than shallower sowings (20–36mm). An estimated risk index to woodpigeons (Columba palumbus) and house sparrows (Passer domesticus) showed that increasing the depth from 25 to 40–55mm reduced the risk by a factor of 3–15 in the mainfield but a lower reduction in risk was achieved in the headlands. Potential risks to birds can therefore be significantly reduced by feasible increases in sowing depth using standard seed drills, at least on light fenland soils.

Following DDT contamination of steers grazing pastures polluted by spray-drift from nearby crops in the Ord Valley of Western Australia, experiments were conducted to determine: 1, the distribution of DDT and metabolites (referred to hereafter as DDT) within the carcase fat tissues; 2. a suitable method of sampling fat from live steers; 3. the rate of decline under local feeding conditions with maintenance feeding for 201 days and with ad lib feeding for a further 156 days. There was no significant difference between the DDT concentrations found in the renal, omental, subcutaneous and scrotal fat. A method of sampling fat from the scrotum permitted repeated sampling of steers in good condition at an operation rate of 15 animals per hour. DDT was lost at a mean rate of 0.0031 log mg kg-1 DDT day-1 during the maintenance feeding period despite a level of 1.5 mg kg-1 DDT in the feed. During the ad lib feeding period the loss was 0.0014 log mg, kg-1 DDT day-1. The distribution of DDT values in the experimental herd was skewed; the implications of this on the amount of sampling necessary to ensure that no animal in a group will exceed minimal accepted values of DDT are discussed.

The genital tracts of 968 slaughtered bulls (46% of which were young post-puberal animals) were examined for defects of a congenital or developmental nature. The overall occurrence of such lesions was 7%. These comprised persistent penile frenulum (0.5%), hypospadias (0.3%), detached urethral process (0.4%), testicular hypoplasia (0.2%), cryptorchidism (0.6%), mesonephric duct abnormalities (1.1%) and bulbourethral cysts, fusion and aplasia (3.6%). Segmental aplasia of the mesonephric duct, not previously recorded in the study area, was found in 4 Shorthorn bulls (0.4%); 2 affected animals were from one herd. In 3 cases of hypospadias (2 from one herd), the urethra communicated with the ventral surface of the penis at the junction of the body and glans through a slit-like orifice. The occurrence of defects observed was generally comparable to that found in bull populations elsewhere but elevated occurrence of several defects in particular herds emphasized the need for further study.

Examination of the testes of 1598 bulls slaughtered at abattoirs in north Queensland revealed the presence of Sertoli cell tumours in one mature and five aged bulls.