GENETIC PARAMETER ESTIMATES FOR GROWTH TRAITS AT DIFFERENT AGES IN NIGERIAN INDIGENOUS TURKEYS

摘要

Precise and accurate genetic parameter estimates are crucial for making sound decisions in many stages of animal improvement programme. Genetic parameter estimates for eight growth traits were determined in 308 turkeys generated from mating pure indigenous parents. PROC MIXED of SAS was used to estimate variance and covariance components of the growth traits. The highest heritability estimates for body weight, breast girth, thigh length, shank length, keel length and wing length were observed at week 1, week 8, week 4, week 16, week 4, and a day old-old, respectively. The repeatability estimates ranged from 0.01 to 0.93 with body weight and body length having the least values at week 20 and week 1, respectively. Negative genetic correlations were observed among the growth traits at a day-old. Also, negative correlations were observed among all the growth traits at week 20 except between body weight and shank length, shank length and wing length, shank length and wing span as well as wing length and wing span. Positive phenotypic correlations existed among all the growth traits measured except among some traits at weeks 1 and 16. Phenotypic correlations observed at week 20 were relatively higher than those observed in other weeks. These results suggested that breeders can select for body weight, breast girth, thigh length, shank length, keel length and wing length of Nigerian indigenous turkeys at week 1, week 8, week 4, week 16, week 4, and a day old-old, respectively. Fewer records are required to estimate response to selection of Nigerian indigenous turkeys when selecting for breast girth at a day-old and body length at week 16.The negative genetic correlation observed among most growth traits at week 20 was an indication of unpredictability among these traits at week 20, so tandem method of selection cannot be used in selecting these traits.