SECTION A: AGRICULTURAL AND HOME SCIENCES
HERITABILITY AND REPEATABILITY ESTIMATES OF GROWTH AND LINEAR BODY MEASUREMENTS OF MALE AND FEMALE BROILER LINES.
This study was designed to estimate the genetic parameters (h2, R ) for growth and linear body measurements in male and female broiler lines in NAPRI, Shika, Zaria. A total of 350 broiler birds were used, which consisted of 100 birds each for sire and dam line and 75 birds each for sire control and dam control. The growth and linear body measurements traits considered are body weight (BW), body length (BL), Body girth (BG), Thigh length (TL), keel length (KL) and Shank length (SL) which were measured biweekly. The heritability estimates for body weight and linear body measurements from 2 to 8 weeks ranged from low to high (0.05± 1.63 to 0.58 ± 0.73) except for thigh length at 8 week which was high (0.81 ± 1.27) in sire line. It ranged from low to high in dam line (0.04 ± 1.50 to 0.9± 0.11). The heritability estimates for sire control ranged from low to high (0.02± 2.11 to 0.46± 1.09). It was also observed low for dam control except in body girth and shank length at 2 weeks of age. The repeatability estimates for body weight were generally low for both the selected lines and the control birds ranging from 0.001 to 0.193 across all ages. Repeatability of linear body measurements were also low though moderate with body girth at 2 weeks (0.350) and body girth at 4 weeks (0.251) for dam line, keel length at 6 week (0.271) for sire line and keel length at 6 weeks (0.291) for dam line. Differences obtained in heritability estimates could be attributed to line effects and sampling error due to small data. Low repeatability estimates revealed that high numbers of records are required to realize high expected response to selection.
Keywords: Broiler birds, Heritability, Repeatability, Body weight, Body linear measurement
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