Heat stress in laying hens is prompted by combinations of environmental temperature and humidity that prevent the bird’s thermoregulatory process from effectively dissipating the heat produced during metabolism [32]. High environmental temperature is the major problem faced by laying hens as well as poultry farmers usually in summer months. The ideal temperature for laying hens is about 20°C [2...

This study aimed to investigate the responses to abrupt changes in feeding and illumination during the egglaying period. Six hens were housed individually in cages under constant environmental conditions, with a photoperiod of 15 h (0400-1900) and ad libitum access to food for 10 days. Then the same hens were subjected to a feed withdrawal trial (between 1200 and 0830), followed by a 5-h reduct...

Prostaglandin F (PGF) concentrations in the serum of laying and nonlaying hens and of cocks at various times during a day were measured by radioimmunoassay. The serum concentration of PGF was higher in laying hens than in nonlaying hens or cocks without regard to time of day. In all birds, the concentration showed a peak at 2 h after onset of light (0700 h). In laying hens on the day of laying ...

At present the laying hen rearing is transformed into alternative housing systems which include a deep litter system. As for the poultry nutrition, the replacement of animal protein with vegetable protein in poultry feed is applied. Therefore, in an experiment we evaluated the quality of eggs from laying hens in the cage system as compared to the deep litter system with vegetable protein substi...

The study aimed to evaluate the potential effects of feeding with phytase transgenic corn (PTC) on organ weight, serum biochemical parameters and nutrient digestibility, and to determine the fate of the transgenic DNA in laying hens. A total of 144 50-week-old laying hens were grouped randomly into 2 treatments, with 8 replicates per treatment and 9 hens per replicate. Each treatment group of h...

BACKGROUND The husbandry systems for laying hens were changed in Sweden during the years 2001 - 2004, and an increase in the number of submissions for necropsy from laying hen farms was noted. Hence, this study was initiated to compare causes of mortality in different housing systems for commercial laying hens during this change. METHODS Based on results from routine necropsies of 914 laying ...

The aim of this study was to localize macrophages in the hen oviduct and determine the effects of age and gonadal steroids on their population. Cryostat sections of oviducal tissues from immature hens (60 d of age), virgin young (175 d of age), and old (620 d of age) laying hens, and immature hens (84 d of age) treated with gonadal steroids were immunostained for macrophages. The population of ...

The goal of this study was to determine whether cell proliferation is increased in the anterior pituitary during an induced molting period in chickens. The anterior pituitaries were collected from: 1) laying hens before initiation of an induced molt (control hens), 2) molting hens 2 to 16 d after cessation of lay, and 3) second cycle laying hens 1 d after returning to lay. Pituitary cephalic an...

An experiment was conducted to evaluate the effects of different levels of mineral and vitamin premix on performance and egg traits of laying hens from 37 to 49 weeks of age. Two hundred and forty laying hens (Hy-Line W-36 strain) were randomly assigned to 5 dietary treatments of four replicates each with 12 hens per replicate). The levels of mineral and vitamin premixes in the experiment were ...