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.
Factors Affecting Feed Efficiency for Egg Production in Selected Strains of Caged Layers
Abstract THE use of individual laying cages for market egg production has gained widespread popularity throughout the southern portion of the United States. Breeding is known to affect body size, rate of production, egg size, and feed conversion. Titus (1928) found that White Leghorn pullets weighing an average of 1,632 grams required 64 grams of feed per day for body maintenance, and 40 grams of feed for each egg produced. Byerly (1941) found annual feed requirement for body maintenance to be 46.8 pounds for three pound laying hens, and 81.4 pounds in the case of seven pound hens. He further determined that for each 100 standard weight eggs (12.5 pounds) the hen must consume an additional 14.2 pounds of feed. Bhuwan et al. (1949) found that with hens laying at a rate of 72 percent, approximately 71 percent of the feed consumed was used for body maintenance, 27 percent for the …
Pasteurella haemolytica serotype 1 colonization of the nasal passages of virus-infected calves.
Nasal passages of calves with a virus-induced respiratory tract disease became colonized by Pasteurella haemolytica serotype 1 after they were inoculated intranasally with P haemolytica. Inoculation with infectious bovine rhinotracheitis virus caused a more severe clinical illness and resulted in a greater degree of colonization with P haemolytica than developed after inoculation with parainfluenza-3 virus. Nasal passages of parainfluenza-3 virus-inoculated calves were colonized to a greater degree with P haemolytica than were those of healthy, nonstressed calves. Calves were susceptible to P haemolytica colonization during or shortly after virus-induced illness, even though they had been previously exposed to P haemolytica and had serum antibody and nasal secretion antibody to P haemolytica.