ABSTRACT The objective was to examine the effects of supplementing different levels of zeolite in the diet of laying hens during the laying phase, at 54 weeks of age, on production performance, egg quality, ammonia volatilization, excreta pH, blood parameters, weight, and organ morphometry. The treatments consisted of a control diet free of zeolite and five diets including increasing levels of zeolite (0.7, 1.4, 2.1, 2.8, and 3.5%). A completely randomized design was adopted with eight replicates of five birds per plot, totaling 240 laying hens, for four 28-day periods. Results were subjected to ANOVA, Dunnett’s test, and regression analysis at 5% probability. The zeolite levels had no significant effect on production performance, egg quality, and blood parameters. The zeolite levels have a significant effect on ammonia volatilization, excreta pH, liver weight, and organ morphometry specifically on the intestinal length. Ammonia and pH reached a linear plateau. Ammoniacal nitrogen levels in the excreta differed from that observed in the control group at all zeolite levels, whereas the pH was lowest at the zeolite inclusion levels of 0.7 and 1.4%. Ammonia volatilization and the pH value of the excreta decreased by 46.9% and 4.6%, when the laying hens consumed diets with 0.93% and 1.19% zeolite, respectively. There was an effect on the relative weight of the organs, with higher liver yield and intestinal length provided by zeolite inclusion. Therefore, zeolite can be included in the diet of commercial layers at up to 0.93% without affecting their production performance or egg quality.

ABSTRACT Exposure to increasing concentrations of CO2 in the first 10 days of incubation may have effects on the development of bird cardiac and respiratory organs. Moreover, the age of breeders can influence hatching performances. This study aimed to investigate the effect of exposure to increasing concentrations of CO2 in the first 10 days of incubation on the morphophysiological development of the digestive system of embryos and chicks from broiler breeders aged 31 and 41 weeks. A total of 860 fertile eggs from the Cobb strain were distributed in a completely randomized design, in a 2 x 2 factorial arrangement, with 2 different gaseous environments (Control (C) - no increase in CO2 concentration and, Hypercapnia (CO2) - a gradual increase in CO2 concentration until reaching 1% on the 10th day) and 2 different broiler breeder ages (31 and 41 weeks). Half of the eggs were obtained from 31-week-old breeders, and the other half from 41-week-old breeders. Compared to the control group, incubation in an atmosphere with 1% CO2 led to an increase in villus heights in the duodenum, jejunum, and ileum of the embryos, with a reduction in villus density in the same segments. Chicks from 41-week-old broiler breeders showed higher villus heights in the duodenum, jejunum, and ileum at day 1 post-hatching, and lower villus density at 7 days. It was concluded that the incubation of fertile eggs in hypercapnia conditions could positively affect the small intestine of embryos and post-hatch chicks.

ABSTRACT In order to explore the effect of estrogen receptor (ESR) gene polymorphism on the egg production performance of quails, the polymorphisms of exon 1, exon 4 and exon 8 of the ESR gene in three Laying Quail Populations of Chinese Yellow quail, Korean quail and Beijing white quail were detected by PCR-RFLP, and their association with the egg production performance of quails was analyzed. The results showed that three genotypes were detected in exon 1, exon 4 and exon 8 of the ESR gene in three quail populations, namely TT, CC and CT genotypes. Among them, the frequency of CC genotype in exon 1 of the ESR gene was the highest in Chinese Yellow quail, Beijing white quail and Korean quail (0.515, 0.600 and 0.723); Exon 4 of the ESR gene had the highest frequency of TT genotype (0.409, 0.617) in Chinese yellow and Korean quails, while CC genotype was the highest in Beijing white quails (0.667).The frequency of TT genotype in exon 8 of the ESR gene was the highest in Beijing white quail and Korean quail (0.708, 0.500), while the frequency of CT gene was the highest in Chinese yellow quail (0.521). The results of association analysis showed that there was no correlation between exon 1 of the ESR gene and quail egg production performance (p>0.05). Exon 4 of the ESR gene was significantly correlated with laying traits such as feed-egg ratio, egg laying number, laying rate and starting weight of quails (p<0.05). Exon 8 of the ESR gene was significantly correlated with feed-egg ratio, egg laying number and egg laying rate of quails (p<0.05).In conclusion, the research shows that the ESR gene can be used as a candidate gene for marker assisted selection of egg production performance of Laying Quails, which provides a theoretical basis for cultivating new egg laying quail lines with better egg production performance.