ABSTRACT

This study was conducted to determine the relationship between biologic markers and quantitative traits in Arbor Acre, Ross and Marshall broiler strains. A total number of 90, each of the three strains were used for the experiment which lasted for 56 days (8 weeks). The experiment was carried out at the Poultry Unit of the Teaching and Research farm of Michael Okpara University of Agriculture, Umudike, where the birds were raised in separate deep litter pens. The experimental layout was a 3 x 3 factorial arranged in a Completely Randomized Design (CRD) with three broiler strains (Arbor Acre, Marshall and Ross) and three age groups (4, 6 and 8 weeks) of each strain, which gives rise to 9 treatment combinations. Each treatment combination (Strain x Age) was replicated thrice, consisting of 30 birds per replicate. Data collected include hematology parameters: hemoglobin (Hb), Packed Cell Volume (PCV), White Blood Cell (WBC), Red Blood Cell (RBC), Mean Cell Volume (MCV), Mean Cellular Hemoglobin (MCH), Mean Cellular Hemoglobin Concentration (MCHC) and biochemical parameters including glucose and total serum protein and body parameters including body weight (BW), body length (BL), shank length (SL), keel length (KL), wing length (WL), breast width (BWD) and drumstick length (DSL). Data collected were analyzed statistically using Pearson Product Moment Correlation as contained in SPSS Software Package. The result obtained showed that in the Arbor Acre, MCHC could serve as a useful marker in week 4 as it was associated significantly with breast length (rp=0.989) and keel length (rp= -0.986), whereas in week 6, serum protein, MCH, PCV, WBC and RBC proved significant markers based on their significant association (P<0.05;P<0.01) with SL (rp=0.975), KL (1p=0.981), DSL (rp= -0.982; - 0.989) and BL (rp= -0.991). In week 8, Hb, WBC, MCV, MCH and MCHC proved to be useful markers for selecting keel length, breast length, body length, body length and thigh width in Arbor Acer. Marshall strain did not record any useful association in the 4° week; in week 6, PCV, RBC and serum protein established significant correlations (P><0.01;P<0.05) with breast length, shank length and wing length; in week 8, only MCV correlated significantly (P><0.05) with shank length (0.886) and keel length (0.985) in the strain. The Ross strain recorded no significant association (P>0.05) between the biological marker and body parameters in week 4; in week 6, Hb and serum protein proved to be useful markers for selecting drumstick length (rp= 1.000) and body length (rp= 0.982) respectively; in week 8, glucose and serum protein may serve as markers for selecting shank length (-0.844, 0.888) and body length (-0.938) in the strain. The highest correlation coefficient in this study was found in the association between Hb and DSL (rp= 1.000) in the Ross strain at week 6; followed by serum protein and wing length (rp= -0.996) and lastly RBC and SL (rp= -0.994) in the Marshall strain at week 6. In the Arbor Acer strain, highest correlation was observed between WBC and BL (rp= -0.991) and between MCH and breast length (rp= 0.991) in the 6" week. In conclusion, due to the limited associations observed in week 4, it may be more reliable to apply the biologic markers in selection programs, starting at the 6 week for the Ross and Arbor Acre broiler strains but at week 4 for the Marshall strain. Due to the non significant association between body weight, which is the most important economic trait and hematology markers, this study advocates that highly polymorphic DNAbased markers which are more reliable should be attempted for improving body weight of broilers.