Heterosis in Fayoumi strain incrossing
Summary Many experiments have proved the superiority of hybrids resulting from incrossing of mbred lines, which have been utilized commercially in poultry production. The aim oi this experiment was to study the effect of incrossing inbred lines of Fayoumi chickens upon their combinability. The results can be summarized as follows: The fertility percentage 96.7 in comparing with 92.9 (L2j while reached in The heavier incross Lz5 X L3!.j had body weight equal to 118, II2 and io3 % in relation to the control at 4, 8 and i6 weeks of age, respectively. Heterosis in body weight became less obvious as chicks advanced in age and alleles responsible for early growth rate showed a great response to incrossbreeding. Incrossbreeding improved feed utilization of Fayoumi chicks. These results show the possibility for improving the native breed by incrossing and detecting the most efficient incrossbreds.
Estimation of general and specific combining abilities from a diallel cross of three inbred lines of Fayoumi chicks
Three inbred lines of Fayoacmi chicks were incrossed in diallel mating system to estimate general and specific combining ability. The inbreeding coefficients in three inbred lines were 25 , 37 .5 and 5o per cent. L 25 showed the highest g.c.a. in fertility and body weight at 8 weeks of age. L 37 ,5 exhibited the best g.c.a. in viability, while L 50 gave the best g.c.a. in hatchability. The inbreeding coefficient of sire had a highly significant effect on both fertility and hatchability while its effect on viability and body weight at 8 weeks of age was not significant. L z5 X L 37 ,5 incrossbred chicks gave the best s.c.a. in viability and body weight, fertility and hatchability.
Efficiency of Feed Utilization in Relation to Body Weight and Egg Production
Abstract Titus (1928–29) has estimated that to produce a standard-weight egg, 40 grams of feed were required over and above that needed for maintenance, and in 1934 estimated that not less than 75 per cent of the total feed consumed by laying hens is used for body maintenance (Titus, 1934). Byerly (1941) calculated that the annual feed requirements for maintenance varies from 46.8 pounds for three-pound birds to 81.4 pounds for seven-pound birds and that for each standard-weight egg, 64.4 grams of feed were required over and above that needed for maintenance. Interesting observations were made by Bird and Sinclair (1939) on the energy required for maintenance, egg production, and changes in body weight of females kept in laying cages. A partial correlation coefficient revealed that the amount of ingested feed is positively and significantly correlated with body size, weight of egg material produced, and changes in body weight. They showed . . .