the effect of the gene for polledness on conception rate and litter size in the damascus goat基因的影响polledness的受胎率和产仔的大马士革山羊.pdf

The effect of the gene for polledness on conception rate and litter size in the Damascus goat A. CONSTANTINOU A. LOUCA A.P. MAVROGENIS Ministry of Agriculture and Natural Resources Department of Agriculture, Nicosia, Cyprus Agricultural Research Institute, Nicosia, prrrsyC Summary Data on 1 709 matings and 1 247 parturitions were used to study the effect of the gene for polledness on conception rate and litter size in the Damascus breed of goat in Cyprus. With one exception all polled sires used in the study proved to be heterozygous Pp for the polled factor P. There was consistent excess of males in the offspring of all mating types with an overall proportion of males (53.1 p: 100) significantly different from the 50:50 ratio. Intersexes (6.0 p. 100) were found only when both parents were polled (Pp X Pp matings). The percentage of intersexes corresponds to an expressivity Y2 = .48 of the P genes for that trait in the PP females. Among alpine breeds y, was between .44 and .57. The percentage of males in excess corresponds to an expressivity of Y, = .16 of the P gene for that trait in the PP females (y, - .43 to .56 in alpine breeds). Theoretically this excess must not been found in horned X polled and horned X horned crossings where no PP genotypes are produced. This discrepancy, as well as the low value of Y, in the Pp polled X Pp polled matings has not been explained. Conception rate for polled (Pp) females was 74.7 p. 100, non significantly different from that of pp ones (76.4 p. 100). Litter size at birth for resp. all born and born live kids was 1.88 and 1.82 in polled goats (Pp) while