Association of Haemoglobin Genotype with Residual Feed Intake in West African Dwarf Does
Summary
The interaction effect of haemoglobin genotypes (HbAA, HbAB) and residual feed intake (RFI) classes (RFILL, RFIMM, RFIHH) on feed efficiency, haematological and serum parameters in on-farm West African Dwarf (WAD) does was studied for pre-selection of breeding animals. Ninety-six does were fed for 112 days. Feed intake was measured daily, body weight and other variables were measured at 28-day intervals. Dry matter intake (DMI); average daily gain (ADG) and feed conversion efficiency (FCE) were computed while body condition score (BCS) was estimated using the five-point scale for goats. Blood samples were collected after 112 days via jugular vein puncture and analyzed for insulin-like growth factor (IGF-I), insulin, leptin, urea and complete cell counts. Phenotypic RFI was calculated for each animal as the residual from a multiple regression model of DMI on ADG and mid-test metabolic bodyweight (BW0.75). The WAD does with heterozygous HbAB genotype had higher serum insulin and IGF-1 concentrations than the homozygous HbAA genotype (P < 0.019). Does within the low RFI (RFILL) class recorded higher IGF-1 (P < 0.050 ), PCV (P < 0.002 ) and Hb concentration (P < 0.038) than does within the medium (RFIMM) and high (RFIHH) classes. The interaction of Hb genotype and RFI revealed significant differences (P < 0.050) on FCE, IGF-1 and monocytes values among does. The result of Hb genotype x RFI class interaction on RFI was not significant (P = 0.077), although values increased numerically in ascending order to rank does into pre-selection classes. WAD does of HbAA and HbAB genotypes with negative-RFI values (-0.004, -0.005) were deemed most efficient nutritionally and could be selected as parents.
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