ABSTRACT.


LUIS LATRILLE L.1, JUAN CARLOS MAGOFKE S.2, EWALD WITKE G.3 Y XIMENA GARCÍA F.4
 

Four hundred .and twenty broiler chickens of two commercial breeds were used (i) to study the effect of feeding two levels ofcrude protein (21 vs. ,25%) during the first 2 weeks of age and (ii) to compare the rearing of chickens in a battery versus on the floor during the period from 4 to 8 weeks of age. Results presented show the live-weight at 8 weeks of age, efficiency of feed utilization, incidence of breast blisters, and mortality.
Strain A weighed 1.455 grams at 8 weeks of age compared to 1.354 grams for strain B, a highly significant difference (P < 0.01). There were no significant differences between the responses to the two levels of protein fed during the first two weeks or between the two systems of rearing the birds during the period from 4 to 8 weeks of age.
Strain A, that showed the best growth, also showed a trend toward better efficiency of feed utilization, particularly for those chickens raised in a battery. However, mortality was highest in the faster growing strain A (4.3% vs. 1.4%). There was sorne incidence of breast blisters in both strains of chick.ens raised in the hattery, but the problern was greater in strain A (7.1% vs. 2.0%) . This problern was not observed in either strain of chicks raised on the floor.

Keywords:
1 Ingeniero Agrónomo M. S., Departamento de Producción Animal. Estación Experimental Agronómica. Universidad de Chile y Profesor Auxiliar de la Escuela de Agronomía, Universidad de Chile.
2 Ingeniero Agrónomo Mag. Sci., Departamento de Producción Animal. Estación Experimental Agronómica. Universidad de Chile y Profesor de Genética Animal de la Escuela de Agronomía, Universidad de Chile.
3 Ingeniero Agrónomo Mag. Sci., Departamento de Producción Animal, Estación Experimental Agronómica, Universidad de Chile.
4 Ingeniero Agrónomo, Laboratorio