Heterosis and phenotypic correlations for shank length, body weight and egg production traits in the Alexandria strains and their crosses with Fayoumi chickens.

The performance features of one paternal (PL) and one maternal line (ML) each, their reciprocal crosses and their crosses with a non-selected Fayoumi population are presented. A clear heterosis was found for hatchability only. Shank length, body weight, fertility, sexual maturity and egg weight were intermediate. Heterosis was observed for the number of eggs in the first 90 days of laying for the ML X PL cross. The performance of the PL and ML and of their reciprocal crosses was generally higher than that of the crosses with the non-selected Fayoumis.

Phenotypic and genetic correlation between egg characters and embryo and chick weights of Alexandria and Fayoumi chickens.

At the Poultry Research Centre of Alexandria University phenotypic and genetic correlations were estimated on the basis of dam averages of three populations between egg quality features, embryo and chick weights. The relationships of individual egg weight, shell weight, and shell thickness as well as the egg shape on the one hand and the embryo weight at 6, 12, and 18 days of age on the other hand were weak and exhibited no uniform trend. The correlations between egg weight and chick weight were also low. The genetic correlations between shell weight and shell thickness and the chick weight up to the eighth week were even negative.

Genetic and phenotypic correlations between duration of fertility and certain traits in Alexandria and Fayoumi chickens.

Two Alexandria lines selected for a high (HL) or low (LL) eight-week body weight, and an unselected Fayoumi line were used to study the duration of fertility, fertility percentage, fertility percentage duration, age at sexual maturity, egg number in the first ninety days of laying, egg weight, eight-week body weight, and body weight at sexual maturity. The fertility could be improved through selection for duration of fertility. Within the lines, early mature pullets had a longer duration of fertility than those matured later. The duration of fertility within the lines is a rather good indicator of eight-week body weight. Within the lines, the duration of fertility increases with the increase in body weight at the age of sexual maturity.

Heritability estimates for the duration of fertility in Alexandria and Fayoumi chickens.

Two Alexandria lines selected for high (HL) and low (LL) body weight and one unselected Fayoumi line were compared for the duration of fertility in both sexes. In the parents, LL had a significantly higher duration of fertility than HL and Fayoumi. In the female progeny, the mean duration of fertility in HL, LL, and Fayoumi were 9.76, 11.20, and 10.66 days, respectively, and the difference among them were highly significant. Based on the sire-plus-dam components of variance, the heritability estimates of the duration of fertility were determined. Heritability estimates obtained by regressed offspring mean on dam estimate were 0.44 in HL, 0.14 in LL, and 0.93 in the Fayoumi. It can be concluded that the genetic variance of this feature - duration of fertility - was relatively high.

Heterosis and heritability estimates of body weight in turkeys.

Crosses and backcrosses were carried out with two commercial varieties of turkeys (Black Bronze and White Ross). The birds of the White Ross strain had higher body weights at 12 and 16 weeks of age than the Black Bronze turkeys. The F 1 crosses were intermediate between the body weights of the parent varieties. For the 12-week body weight, heritability estimates were 0.62, 0.74, and 0.68 on the basis of the sire, dam, and sire plus dam components, respectively. The h2 values for the 16-week body weight were 0.55, 1.06, and 0.80, respectively. The estimates of maternal effects were 0.03 and 0.13 for the 12- and 16-week body weights.

A comparison of the effect of oleandomycin and oxytetracycline supplementation on the growth and the meat quality of Dokki-4 chicks reared in hot weather.

1000 chickens were used to investigate up to 24 weeks under high environmental temperatures the addition of different types (oxytetracycline and oleandomycin) and different levels (5 or 20 ppm) of antibiotics to the basal diet. Supplementation with 20 ppm had--with both types of antibiotics--a marked positive effect on the growth rate and various quality characteristics of the products. The effect was higher in male animals than in females.