Genetic Evaluation of Growth Traits in New Synthetic Rabbit Line in Egypt

Abstract

Native Middle Egypt Rabbit breed (NMER) crossbred with Gaint Flander rabbits to create a synthetic line and this study aimed to evaluate the genetic estimates of this synthetic line with comparing to the purebreds. A crossbreeding was carried out by mating bucks of Gaint Flander (G) with does of NMER (N) to get F1 (½N½G), then does and bucks of F1 were mated to get the F2 (½N½G)2, followed by two generations of inter se-mating to get a new synthetic line is called Egy-line with a genetic structure of ((½N½G)2)2. Heritability estimates for body weights were generally moderate and ranging from 0.10 to 0.24, while the estimates of heritability for growth rate were low and moderate and ranging from 0.01 to 0.23. Common litter effects of body weight were large as weaning (0.61), then declined gradually at the rabbit grew older. Also, the same trends were observed for relative growth rate (RGR). The direct additive effects were positive and highly significant for all body weights at different ages, favoring Gaint Flander and heavier comparing with NMER rabbits. Most relative growth rates during different intervals were non-significant. Gaint Flander was highly significantly and heavier in maternal additive effects in in different weeks of age comparing with NMER rabbits. Direct heterosis effect for most bodyweight was positive and highly significant, and percentages of direct heterosis increased generally with the advance of age. Maternal heterosis for growth rates from 5 to 6, 8 to 10, and 10 to weeks were positive, only. Direct recombination effects for most bodyweight were positive and highly significantly exclude weight at 5 and 6 weeks. It is concluded that a new synesthetic line (Egy-line) has proven its superiority and performance well in all different body weights and most growth rates compared to other parents and crossbreds.