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 ...

The dopaminergic (DAergic) system plays a pivotal role in incubation behavior via the regulation of prolactin (PRL) secretion in birds, however the role of the DA/PRL system in rearing behavior is poorly understood. The objective of this study was to investigate the relationship between the DA/PRL system and rearing behavior in a gallinaceous bird, the native Thai chicken. Incubating native Tha...

The serotonergic system has been shown to be implicated in the regulation of mood and feeding behavior. Previous studies have identified a polymorphism in the 5'-flanking region of the serotonin transporter ( 5 - HTT ) gene of Lohmann Brown (LB) laying hens. The deleted variant D was found to be associated with increased body weight. The objective of this study was to address whether the increa...

A study was conducted to evaluate skeletal quality and eggshell parameters of molted hens at the end of the second laying cycle. Sixty Single Comb White Leghorn hens were used for this study. There were 2 controls and 4 molting treatments: full-fed control 1 (82 wk old; FF1), full-fed control 2 (122 wk old; FF2), feed withdrawal (FW), 100% alfalfa (A100), 90% alfalfa/10% layer ration (A90), and...

In many cases health and welfare problems are observed in organic egg production systems, as are high environmental risks related to nutrient leaching. These disadvantages might be reduced if the layers are allowed to utilise their ability to forage to a higher degree thereby reducing the import of nutrients into the system and stimulating the hens to perform a natural behaviour. However, very ...

The influence of AME(n) concentration of the diet on productive performance and egg quality traits was studied in Hy-Line brown egg-laying hens differing in initial BW from 24 to 59 wk of age. Eight treatments were arranged factorially with 4 diets varying in energy content (2,650, 2,750, 2,850, and 2,950 kcal of AME(n)/kg) and 2 initial BW of the hens (1,733 vs. 1,606 g). Each treatment was re...

A study was conducted to evaluate the effects of dietary supplementation of phytase B (product of the Aspergillus niger phyB gene expressed in Trichoderma reesei) on feed intake, laying performance, eggshell quality, and on phosphorus and calcium balance in laying hens. Seventy-two, 40 weeks old Hy Line Brown hens were fed for 14 weeks the following four phosphorus-deficient (0.12% nonphytate p...

An experiment was conducted using 336 White Leghorn hens (60 wk of age) randomly assigned to one of four treatments that consisted of feed removal for 4 or 10 d or no feed removal with ad libitum access to 95% corn or 95% wheat middlings molt diets that contained supplemental minerals and vitamins. At the end of the 4- or 10-d feed removal period, hens on these treatments were provided with the...

This study was conducted to evaluate the effect of dietary β-mannanase supplementation and palm kernel meal (PKM) inclusion (5%) on laying performance, egg quality and nutrient utilizability of laying hens with 73 weeks of age. A total of 240 Lohmann brown laying hens with average 77.5% egg production were randomly allocated with 60 hens per treatment, 4 replicates per treatment and 15 hens per...

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 ...