Document Type : Original Article
Author
Animal Production Research Institute, Agriculture Research Center, Ministry of Agriculture, Dokki, Cairo, Egypt.
Abstract
Data collected on 765litters produced from 261 does and 69 sires of New Zealand White for five consecutive years. The data of doe traits (DBW = doe body weight, DPE = doe production efficiency), litter traits (LSB = litter size at birth, LSW = litter size at weaning, LW1, LW2, LW3 and LW4 = litter weight at 1st, 2nd, 3rd week and 4th week of age respectively, litter gain traits (LG1= litter gain from birth to 1st week, LG2= litter gain from birth to 2nd week, LG3= litter gain from birth to 3rd week, LG4= litter gain from birth till to 4th week of age resp.) and lactation traits (MY1, MY2, MY3 and MY4) = milk yield during the 1st, 2nd, 3rd and 4th week respectively, milk conversion ratio (MCR1, MCR2, MCR3 and MCR4 = milk conversion ratio from kindling till 1st, 2nd, 3rd and 4th week respectively (g litter gain per g of milk suckled during 1st, 2nd, 3rd and 4th weeks respectively of lactation).Heritability for doe traits were low (0.05 for DBW and 0.08 for DPE);h2 were low ranged from 0.01 to 0.06 for litter size (LSB and LSW); from 0.0 7 to 0.20 for litter weights.
The trend was the same in the case of both litter gain and milk traits. The highest repeatability R2estimates (0.74 and 0.76) were obtained for DBW and MCR4. R2 estimates for other studied traits tended to be low to moderate in magnitude and ranged from 0.01 to 0.20 for litter traits and ranged from 0.14 to 0.40 for milk traits. The ranges of transmitting ability were 248.29 and 0.234 grams for DBW, DPE; ranged from 0.297 to 880.54 grams for litter traits, ranged from 0.383.22 to 416.29grams for milk yield, finally ranging from 0.584 to 5.06 % for milk conversion ratio from kindling till 1st, 2nd, 3rd and 4th week respectively. The percentages positive transmitting ability estimates were 48.41 and 47.52% for doe traits, ranged from 46.37 to 52.99% for litter traits and ranging from 33.63 to 46.50% for lactation traits. The ranges of transmitting abilities estimates for top 25% of animals were 121.28 and 0.117% for doe traits, ranged from 0.124 to 0.841% for litter traits. The rank correlation was negative, moderate and highly significant between DBW and DPE were generally positive, moderate and high for litter sizes and litter weights traits and ranged from 0.22 to 0.94. The same trend between litter traits and litter gains except between LSB and LG2 and LSB and LG3 were 0.09 and -0.17 resp. The values of rank correlation of lactation traits were negative, positive, moderate or high and characterized by highly significant. Generally the values of genetic trend were varied and increased by increasing years for all traits under studies; the higher values were for LSW, LW4, LG4, MY1, MY2 and MRC4.
Conclusively, although the heritability of doe, litter and lactation were low or\and moderate, it appear to be within the range of values notified in the literature; and suggest that genetic selection must be done considering a higher number of related animals and more accurate statistical methods of selection for doe, litter and lactation in rabbits. So genetic evaluation and continuous selection for economic traits is very useful to increase its productive and reproductive performance. This will help the rabbit's producers' to increase their production and profits.
Keywords
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