Selection Indexes for Efficient Meat Production Capacity from New Zealand White Rabbits
Selection Indexes for Efficient Meat Production Capacity from New Zealand White Rabbits
Elfadil, G.E.1,3, G.F. Gouda1*, M.A. Rashed2, A.R. Shemeis1
ABSTRACT
Abstract | To enhance meat production capacity in New Zealand white (NZW) rabbits, six unrestricted, two single-restricted and one double-restricted selection indexes were constructed using phenotypic and genetic parameters estimated using multi-trait animal model on 458 growing rabbits, progeny of 25 bucks and 92 dams. The aggregate genotype involved post-weaning daily gain (DG), higher percentages of dressing (DP) and boneless meat (BMP). Sources of information were various combinations from weaning weight (WW), slaughter weight (SW), DG, body length (BL) and round girth (RG). The maximum accuracy of selection (RTI = 0.71) was obtained from the selection based on the full index (I1) containing the five sources of information. Dropping WW and RG from the full index simultaneously, to form the best reduced index (I3), is expected to reduce the accuracy of selection to 0.70. Selection based on DG alone (I5) seems to be the most efficient single trait index (RTI = 0.57). Selection based on I1 (Full index), I3 (best reduced index) and I5 (best single trait index) is expected to develop rabbits with faster DG (3.88 to 4.31 g/day), higher DP (0.01 to 0.10 unit) and BMP (0.03 to 0.06 unit). This improvement in the aggregate genotype traits is expected to be associated with unfavorable genetic changes in carcass weight distribution and in carcass composition. Restricting the full index to result in zero genetic change in Muscle:Fat ratio (M:F) and hind leg percentage (HLP), separately, (I1(HLP) and I1(M:B), respectively) is expected to reduce the RTI by 17% and 23%, respectively. Restricting the same index (I1) to result in zero genetic changes in both of HLP and M:B ratio, simultaneously (I1(HLP, M:B)), is expected to reduce the RTI by 20%. It could be recommended that in case of sub-optimal levels of HLP and M:F ratio, the use of the best reduced index (I3) is expected to develop NZW rabbits with more efficient capacity in meat production, while the use of the double restricted form of the full index I1(HLP, M:B) is recommended to be apply in case of optimal levels of both of HLP and M:F ratio.
Keywords | New Zealand white rabbits, Selection indices, Meat production capacity, Carcass weight distribution, Carcass composition
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September 2023
Vol. 11, Iss. 9, pp. 1411-1596
