Genetic evaluation of fur traits in New Zealand White and Californian rabbits raised on high ambient temperature

M.H. Khalil, M.K. Ibrahim, A.S. El-Deghadi

Abstract

An experiment on New Zealand White (NZW) and Californian (CAL) rabbits was carried out to evaluate genetically post­weaning coat traits of these two breeds raised under hot conditions. Data on 24680 and 10549 fibers collected from 1234 NZW and 520 CAL weaned rabbits were used, respectively. At 8 and 12 weeks of age, post-weaning coat traits included average hair length in cm (HL), hair diameter (µm) in down hair (HDD) and guard hair (HDG), medulla diameter (µm) in down hair (MDD) and guard hair (MDG), and medullation percent in down hair (PMD) and guard hair (PMG). Variance components and sire heritabilities were estimated for these traits using Restricted Maximum Likelihood (REML) procedure. Transmitting abilities (TA) for these traits were estimated using a single­trait Animal Model (AM).

Most postweaning coat traits in CAL were slightly higher than those in NZW. The estimates at 8 and 12 weeks, respectively were 2.4 and 3.0 cm in NZW vs 2.4 and 3.1 cm in CAL for HL, 12.2 and 18.8 µm in NZW vs 12.2 and 18.9 µm in CAL for HDD, 62.1 and 89.1 µm in NZW vs 62.3 and 88.9 µm in CAL for HDG, 10.2 and 16.4 µm in NZW vs 10.2 and 16.4 µm in CAL for MDD, 51.4 and 78.1 µm in NZW vs 51.5 and 77.8 µm in CAL for MDG, 82.2 and 87.1 % in NZW vs 83.5 and 86.3 % in CAL for PMD, and 82.2 and 87.4 % in NZW vs 82.6 and 80.5 % in CAL for PMG. Percentages of phenotypic variation in NZW and CAL for coat traits at earlier ages were slightly higher than at older ages with exception of HL. Except HL and HDD in both breeds, sire heritabilities for coat traits were low or somewhat moderate. Heritabilities for all coat traits in CAL rabbits at 8 and 12 weeks of age were higher than in NZW: 0.667 and 0.775 in CAL vs 0.357 and 0.392 in NZW for HL, 0.326 and 0.304 in CAL vs 0.401 and 0.246 in NZW for HDD, 0.051 and 0.142 in CAL vs 0.053 and 0.116 in NZW for HDG, 0.046 and 0.356 in CAL vs 0.053 and 0.075 for MDD, 0.058 and 0.174 in CAL vs 0.057 and 0.119 in NZW for MDG, 0.008 and 0.132 in CAL vs 0.052 and 0.031 in NZW for PMD and 0.074 and 0.047 in CAL vs 0.055 and 0.048 in NZW for PMG. The largest differences in TA for most coat traits were recorded in CAL breed and the lowest differences were observed in NZW. In favor of CAL breed at 12 weeks of age, there was a large range in TA between NZW and CAL rabbits with a difference of 2.474 cm for HL, 0.755 µm for HDD, 0.906 µm for HDG, 0.818 µm for MDD, 1.181 µm for MDG, and 1.5 % for PMO. Among coat traits, the largest percent of positive TA was recorded for HDD followed by HL, MDD and MDG, while the lowest percent was recorded for HDG.


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 Universitat Politècnica de València

 

Official journal of the World Rabbit Science Association (WRSA)

 

e-ISSN: 1989-8886     ISSN: 1257-5011   https://doi.org/10.4995/wrs