Differential reproductive investment by the mother can critically influence offspring development and phenotype, and strong selection is therefore expected to act on such maternal effects. Although a genetic basis is a prerequisite for phenotypic traits to respond to selection and thus to evolve, we still know very little about the extent of heritable variation in maternal effects in natural po...

OBJECTIVES Atherosclerosis is the main leading cause of cardiovascular diseases. The purpose of this study was to assess the potential preventive effect of egg yolk HDL on the atherosclerosis plaque formation. MATERIALS AND METHODS Thirty rabbits were divided into five groups: A; normal diet, B; hyper-cholesterolemic diet, C; hypercholesterolemic + 400 mg/kg egg yolk HDL D; hypercholesterolem...

Males and females are in conflict over parental care, as it would be favourable for one parent to shift labour to the other. Yolk hormones may offer a mechanism through which female birds could influence offspring traits in ways that increase the relative investment by the male. We studied the role of yolk androgens in mediating sexual conflict over parental care in the collared flycatcher (Fic...

The aspect of the oogonia during their premitotic DNA synthesis and of the premeiocytes during their premeiotic DNA synthesis was studied in turtles by autoradiography, after injection of 3H-thymidine. As in the adult laying quail, the intrafollicular oocytes of the adult turtle go through three successive stages: prelampbrush, lampbrush and postlampbrush. During the prelampbrush and lampbrush ...

Calcium, magnesium, copper, iron and zinc are stored in hens’ egg yolk and, except for copper, the majority of these minerals are located in egg yolk granules (Table 1). Presumably, up to 90% calcium, magnesium, iron and zinc are firmly bound in the phosvitin-lipovitellin complex of granules (GREENGARD et al., 1964; TABORSKY, 1980; TUPPER et al., 1954). As was discussed by Richards, copper ions...

in a 2  3  2 factorial arrangement, 144, fifty–four-week-old laying hens, in 12 treatments with 12 replicates for each treatment, received one of 12 diets based on maize or wheat containing three levels of dried tomato pomace (dtp: 0, 50 and 100 g/kg) as a substitute for wheat bran, and two levels of pigment (0 and 900 mg/kg), for 9 weeks. weight gain (wg), egg production (ep), egg weight (ew...

this study aimed to decrease the cholesterol content of egg yolk of laying hens through inclusion of barley malt rootlets in the diets. forty-two, 54-week-old, lohman laying hens were fed for a 12 weeks laying period on 3 iso-caloric and iso-nitrogenous diets contained 0 (control), 25.5 or 51.1g barley malt rootlets/kg. inclusion of barley malt rootlets at 25.5 or 51.1g/kg diet significantly de...

In many insects, development of the oocyte arrests temporarily just before vitellogenesis, the period when vitellogenins (yolk proteins) accumulate in the oocyte. Following hormonal and environmental cues, development of the oocyte resumes, and endocytosis of vitellogenins begins. An essential component of yolk uptake is the vitellogenin receptor. In this report, we describe the ovarian express...

Gillam & Heilbron (1935) in a study of the effects of feeding maize and grass on the composition of yolk pigment have shown that xanthophyll is the principal pigment of egg yolk, although cryptoxanthin and B-carotene are also present, the former sometimes in amounts that contribute appreciably to the total vitamin A activity of the yolk. In view of this, the extent of the variations in the cryp...