IMPROVEMENT IN PRODUCTIVITY OF INCUBATION OF THERMAL HANDLING OF EGGS OF DISTINCT LIGHT MATRIX WEIGHTS

The objective of the experiment was to evaluate the influence of thermal manipulation on the improvement of hatching eggs of different weights of light matrices in the last embryonic stage. The experiment was carried out in a commercial hatchery of light laying hens, located in Birigui - SP, Brazil. 1950 light-colored eggs of the Dekalb White commercial strain were used. The eggs were classified among different sizes and n in incubation trays. In the period from 19 to 21 days, two incubator machines were used, where the first machine maintained the temperature and humidity values of the hatchery's standard air (37.0 ° C and 60% RH) and in the second machine the temperature was adjusted to 37.7 ° C with 60% RH. The treatments differed according to the residence time in the second machine, and egg weight (G and M) controls T1 (0h-G) and T6(0h-M), 1 hour T2(1h-G) and T7(1h-M), 3 hours T3(3h-G) and T8(3h-M), 6 hours T4(6h-G) and T9(6h-M) 9 hours T5(9h-G) and T10 (9h-M). The design was completely randomized, in a 2X5 factorial scheme. Regarding thermal stimulation, the best results were observed in the 1h-G treatment. However, in the productive life of these birds, the thermal stimulation showed no influence. Concluded that for large eggs (G), the residence time of 1 hour (T2), obtained a better index of commercially viable females and lower rates of late-stage embryo mortality and shelter.

Fecundity of the langoustine Metanephrops mozambicus Macpherson, 1990 (Decapoda, Nephropidae) in eastern South Africa

The fecundity of the langoustine Metanephrops mozambicus Macpherson, 1990 was investigated using egg-bearing females caught in commercial trawls off eastern South Africa. A generalized linear model (GLM) framework was used to assess fecundity and egg diameter relative to langoustine carapace length (CL) and egg developmental stage. Fecundity ranged from 407 to 1606 eggs per clutch, increased with increasing CL and decreased between egg stages 1 and 4. Egg diameter increased significantly between stages 1 and 4 and larger females carried larger eggs. Egg loss during incubation was estimated at 10%. Four egg stages used during field sampling were re-examined and illustrated. A late stage embryo removed from an egg about to hatch appeared to be adapted to a benthic, rather than natatory existence.

INFLUENCE OF DATE OF OVIPOSITION ON EGG HATCHING AND EMBRYO SURVIVAL IN THE RED TURNIP BEETLE, ENTOMOSCELIS AMERICANA (COLEOPTERA: CHRYSOMELIDAE)

Embryological development and hatching for the red turnip beetle, Entomoscelis americana Brown, were studied at 20 °C. In eggs kept at this temperature for > 12 days, embryological development proceeded until a late stage embryo was formed, at which time the embryo entered diapause for the winter. The time required for 50% of the eggs to reach the late embryo stage was estimated to be 11 days. The late embryo stage was not reached before winter in eggs kept at 20 °C for < 11 days, but most of them survived and hatched. Embryogenesis proceeded normally after winter without any apparent adverse effects, and hatching was delayed by the amount of time required to complete embryogenesis. Although it was not essential for the eggs to reach the late embryo stage to overwinter successfully and hatch, a critical minimum stage of development had to be reached during embryogenesis for the eggs to survive. The critical minimum stage of development occurred in the germ band formation stage and was reached during the first 1.5 days of embryogenesis. Most of the eggs laid from 1 to 15 September 1980 and kept outdoors reached the late embryo stage before winter and hatched the next spring; those laid from 15 September to 15 October reached the critical minimum stage of development before winter and also hatched successfully; and those laid after 15 October did not hatch, because they apparently had not reached the critical minimum stage. An evaluation of the data for the eggs kept outdoors and of atmospheric air temperature data suggested that embryo death due to eggs not reaching the critical minimum stage of development before winter normally should not be an important factor in the population dynamics of E. americana in the rapeseed- and canola-growing areas of western Canada. The ecological significance of the data is discussed.