In this study we investigated the role of corticosterone (B) in regulating the proportion of laying females, timing of breeding, reproductive output (egg size and number), and yolk precursor levels in chronically B-treated female zebra finches (Taeniopygia guttata). Corticosterone treatment via silastic implant elevated plasma B to high physiological (stress-induced) levels (24.1 +/- 5.3 ng/ml ...

Like many behaviors, Caenorhabditis elegans egg laying alternates between inactive and active states. To understand how the underlying neural circuit turns the behavior on and off, we optically recorded circuit activity in behaving animals while manipulating circuit function using mutations, optogenetics, and drugs. In the active state, the circuit shows rhythmic activity phased with the body b...

the experiment was designed to study the changes in production performance and egg quality of old laying hens after injection of different doses of growth hormone (gh) and testosterone (ts). a total of 160 old laying hens (hyline w-36) at 73 wks of age were randomly assigned to four treatments with four replicates and 10 birds in each replicate in a completely randomized design. treatment group...

Egg laying in the pond snail Lymnaea stagnalis is triggered by a discharge of the neuroendocrine caudodorsal cells (CDCs). The CDCs expresses three different caudorsal cell hormone (CDCH) genes. This gene family expresses, in total, 11 different peptides among which is the ovulation hormone. Besides the CDCs, the CDCH gene family is expressed in other central and peripheral neurons. In this stu...

Most animals reproduce seasonally. They time their reproduction in response to environmental cues, like increasing photoperiod and temperature, which are predictive for the time of high food availability. Although individuals of a population use the same cues, they vary in their onset of reproduction, with some animals reproducing consistently early or late. In avian research, timing of reprodu...

Experimental synchronization of onset of incubation was employed in laboratory held zebra finches Taeniopygia guttata to study whether differential resource allocation and possible bias of offspring sex in subsequent eggs in the laying order could mitigate the effects of hatching asynchrony. We found that egg mass increased with laying order, but offspring sex was not related to laying order. A...

Incubation starts during egg laying for many bird species and causes developmental asynchrony within clutches. Faster development of late-laid eggs can help reduce developmental differences and synchronize hatching, which is important for precocial species whose young must leave the nest soon after hatching. In this study, we examined the effect of egg laying sequence on length of the incubatio...

this experiment was conducted to evaluate the effects of using of zizaphora (thymyus valgaris), peppermint (lamiaceae menthapiperita), menta pulagum (oreganum valgare) medicinal plants on performance, egg quality, blood and immunity parameters of laying hens. this experiment was conducted in a completely randomized design with 288 of hy line (w-36) laying hens in 8 treatments and 3 replicates (...

BACKGROUND Nutrition intake during growth strongly influences ovarian follicle development and egg laying in chicken hens, yet the underlying endocrine regulatory mechanism is still poorly understood. The relevant research progress is hindered by difficulties in detection of leptin gene and its expression in the chicken. However, a functional leptin receptor (LEPR) is present in the chicken whi...

in order to evaluate eight different protein sources in honey bee nutrition, some experiments were conducted as a completely randomized designs with four replicates and three steps incubator, field and overwintering in isfahan region. protein sources were lentil flour, soybean flour, soybean meal, bread yeast, wheat gluten, skim milk powder, fish meal and pollen. results showed that the longevi...