The trials were conducted to assess the effects of long-term feeding with phytase transgenic corn (PTC) to hens on laying performance and egg quality, and investigate the fate of transgenic DNA and protein in digesta, blood, tissues, and eggs. Fifty-week old laying hens (n = 144) were fed with a diet containing 62.4% PTC or non-transgenic isogenic control corn (CC) for 16 weeks. We observed tha...

The offspring of brood parasitic birds benefit from hatching earlier than host young. A proposed but little-known strategy to achieve this is 'internal incubation', by retaining the egg in the oviduct for an additional 24 h. To test this, we quantified the stage of embryo development at laying in four brood parasitic birds (European cuckoo, Cuculus canorus; African cuckoo, Cuculus gularis; grea...

Turkey hens can rapidly shift from a laying condition to one characterized by ovarian regression, incubation behavior, and hyperprolactinemia. Although remarkable changes occur in hormonal profiles as turkey hens pass from a laying to an incubating state, studies have not been undertaken to examine histochemical alterations of functionally relevant pituicytes in the adenohypophysis. The objecti...

this experiment was conducted to evaluate the effects of different levels of portulaca oleracea (po),medicinal plant, on performance, egg traits, blood biochemical and immunity parameters of laying hens. one hundred eighty hi-line (w-36 strain) mature laying hens 65 up to 76 weeks of age were allotted in a completely randomized design consisting of 5 treatments and 3 replicates (12 birds per re...

Simultaneously dependent siblings often compete for parentally provided resources. This competition may lead to mortality, the probability of which may be a function, in part, of the individual offspring's production order. In birds, serial ovulation followed by hatching asynchrony of simultaneous dependents leads to differences in post-hatching survival that largely depend on ovulation (laying...

New housing systems for commercial egg production, furnished cages and non-cage systems, should improve the welfare of laying hens. In particular, thanks to the presence of a litter area, these new housing systems are thought to satisfy the dust-bathing motivation of hens more than in conventional cages, in which no litter area is present. However, although apparently obvious, there is no concr...

During recent decades productivity of laying hens increased substantially (Elliot, 2008). Not only egg number, egg mass, and feed conversion has increased but also persistency of lay has improved. As such, this must have implications on the optimal amino acid nutrition of current laying hen strains. Simply stated, increasing egg mass output per hen means an increased amino acid output which has...

We studied the reproductive biology of a box-nesting population of Tree Swallows Tachycineta bicolor in southeastern Wisconsin, USA. We were interested particularly in the relationship between laying order and hatching order and the extent to which each was a predictor of nestling body mass. We found that laying order was a significant predictor of hatching order. Laying and hatching order were...

1. Concentrations of retinal (vitamin A(1) aldehyde) in the plasma and liver of laying hens, mature cockerels, immature pullets and pullets undergoing sexual maturation have been measured. 2. The plasma of laying hens contained about 8mug. of retinal/100ml., about ten times that found in the plasma of mature cockerels and immature pullets. In laying hens that had received large doses of retinyl...

Much work has been done during recent years in investigating the calcium partition in the blood of laying hens. From this work an attempt has been made to determine the nature of the non-diffusible calcium. Although Laskowski (1) and Benjamin and Hess (2) investigated the partition of inorganic phosphorus in connection with the study of calcium in the serum of the laying hen, little has been do...