Document Type : Research articles.
Authors
Poultry Production Dept., Faculty of Agriculture, Fayoum Univ., Egypt.
Abstract
Data of blood and/or plasma constituents of three weeks old Japanese
quail were used to predict the growth and some carcass traits of 6 weeks old
quail. Stepwise regression analysis was performed to partition the variability in
growth and carcass traits of three lines of Japanese quail differing in genetic
background. The first and second lines were selected over three generations for
high six week-body weight (HBW6) and high 0-6 week growth rate (HGR0-6)
respectively, whereas the third randombred control line (RC) was kept in order
to facilitate comparison among lines. The results cleared that the most
important predictor for live body weight at six weeks of age (LBW6) in both
males of RC and males of HGR was thyroxine (T4). Both plasma total lipids
and total proteins (TL and TP) were the best predictors for LBW6 for females
of RC line. Model 2 which used hemoglobin (Hb) and T4 was the best model
for predicting LBW6 for males of HBW6. Whereas, TL was the most important
predictor for LBW6 for females of HBW6 line. The most important predictors
for feed conversion (FC) were TL and T4 for males of RC line, white and red
blood cells (WBC and RBC) for females of RC, T4 and packed cell volume
(PCV) for males of HGR0-6, triglycerides (TG) and TL for females of HGR0-6,
TL and WBC for males of HBW6 and growth hormone (GH) and PCV for
females of HBW6 line. Performance index (PI) was predicted through TL and
albumin (Alb) for males of RC, TP and GH for females of RC, T4 and PCV for
males of HGR, TG and TP for females of HGR, TL and ratio of
triiodothyronine to thyroxine (T3/T4) for males of HBW6 and TG and T3/T4 for
females of HBW6. For predicting dressing% in all studied groups, the most
important predictors were T3/T4 and TP for males of RC, TP and GH for
females of RC, ratio of T3/T4 and T3 for males of HGR0-6, Alb and TP for
females of HGR0-6, PCV and RBC for males of HBW6, Alb and T3/T4 for
females of HBW6, respectively. Carcass% for all studied groups could be
predicted using these predictors: PCV and GH for males of RC, GH and TG for
females of RC, GH and RBC for males of HGR0-6, WBC and T3 for females of
HGR0-6, T3/T4 and Hb for females of HBW6, respectively. The most important
predictors for boneless meat% (BLM) were RBC and TP for males of RC, Hb
and Alb for females of RC, TG and T4 for males of HGR0-6, TP and T4 for
females of HGR0-6, T3/T4 and Alb for males of HBW6 and TL and Hb for
females of HBW6, respectively. The major predictor in determining protein%
for both males and females of the HBW6 line was T3. The most important
predictors for fat% were T3/T4, TL and TP in a descending order for males and
females of the RC line and males of HBW6, respectively. The predicted traits
were insignificantly differed than the actual values or percentages
(P>0.05). Therefore, results of the stepwise regression analyses revealed that
either certain studied hematological values or plasma constituents at three
weeks of age in studied lines of both sexes could be used to predict carcass and
growth productive traits in Japanese quail with high precision and low error.
Keywords
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