Estimation of genetic parameters for egg production traits in Japanese quail that selected for immune responses and fed different level of dietary L-arginine

Abstract

This study was conducted in the fields of the Department of Animal Production - College of Agriculture at Kirkuk University for the period from 6/14/2021 to 7/30/2022. 750 quail chicks were supplied from the Poultry Research Station of the Agricultural Research Department in Abu Ghraib. The chicks were fed the starter ration until the age of 30 days, and then they were fed the production ration. At the age of 4 weeks, the chicks were vaccinated with the attenuated Newcastle vaccine, and the chicks were divided into six experimental treatments: the first treatment represented the negative control group that was not vaccinated and did not have the amino acid arginine added to it, the second treatment represented the positive control group whose chicks were vaccinated with the Newcastle vaccine with no arginine added to their diet As for the third and fourth treatments, they were vaccinated with the Newcastle vaccine with the addition of 5% arginine higher than the bird''s needs. The fifth and sixth treatments represented groups of birds vaccinated with the Newcastle vaccine, while feeding the birds with diets to which the amino acid arginine was added, 10% higher than the bird''s needs. A week after the initial immunization, the bird was vaccinated again with Newcastle vaccine, and the immune level was examined by the agglutination test to find out the level of the birds'' immune response, dividing them into two levels of high immune response and low immune response. This process was repeated for the next three generations. The characteristic of egg production at the age of 90 and 120 days, and the egg mass was recorded. The data were analyzed according to the general linear model method using the ready-made statistical program SAS. The genetic equivalent and the genetic and phenotypic correlations were estimated. The characteristics of egg production decreased until the age of 90 and 120 days, as well as the mass of eggs at the age of 120 days, compared to the base population (21.61 vs. 34.84), (22.01 vs. 26.53), (323.47 vs. 545.97), respectively. The egg mass was significantly affected by the level of immunity and the percentage of added arginine, where the highest value of the egg mass was for birds selected for the high immune level and to which arginine was added by 10% higher than the needs of the bird. Estimates of genotyped egg production at 90 and 120 days of age and egg mass at 120 days of age were (0.64, 0.65 and 0.21), respectively. The results showed weak genetic correlations (0.0263) between egg production at the age of 90 days and egg production at the age of 120 days, but the phenotypic correlations were high (0.6248) between egg production at the age of 90 days and egg production at the age of 120 days. The current study indicates that the selection of birds according to the immune response against Newcastle disease led to decrease in egg production and egg mass. Addition the Arginine amino acid did not increase production at the age of 90 and 120 days. While the addition of arginine 10% led to an increase in the egg mass.