Abstract: The present study was conducted to identify the polymorphic blood group systems and their specific antigenic factors in a herd of Friesian cows and heifers belonging to Sakha and Karada Animal Experimental Stations, Animal Production Research Institute, Ministry of Agriculture, Kafr EI-Sheikh. The association between both polymorphic blood groups and antigenic factors of each blood group system on one hand and some productive and reproductive traits within the herd under consideration on the other hand was also studied.
Three hundred and eighty five healthy Friesian cows (141) and heifers (244) were used for blood typing. The heifers only were subjected to a further investigation of the association between polymorphic systems and the productive and reproductive traits. The ordinary feeding systems and management were fOllowed.Productive traits involved the following:
1 - Prewconing growth performance (e.g., birth and weaning weights, total
and daily gain and Suckling period.
2- Milk yield (e.g. initial 90-D yield, 305-D yield, lactation and dry
periods.
3- Milk composition (fat, protein, lactose total solids and solids not fat
percent at mid lactation.The reproductive traits included: age at first and
second calving, calving interval, days open and number of services per
conception.
The immunogenetic work was done with standard reagents for blood typing with their antigenic factors.
Results obtained could be summarized in the following:
1- Hemolytic tests revealed the presence of 8 polymorphic blood group
loci namely; A,B,C,FV,S,L,J and M.
2- The inheritance and gene frequencies of such polymorphic systems
has been demonstrated.
3- The A, L, M and J polymorphic systems,inspite of the considerable
differences of their gene frequencies, they were expressed lmost similar pattern(i.e., silent and active alleles).The silent alleles produced no detectable products on blood typing tests. Genotypes of both silent and active alleles were homozygous. Gene frequencies of the active alleles were in the descending order of M,J,A and L being 0.92, 0.84, 0.59 and 0.34, respectively.
4- The frequency distribution of the classes of the FV poly morphic system was 60.5,34.5 and 5.2 % of FF, FV and W, respectively. It means that the F allele is over whelimingly predominates in the codominant FV -polymorphic system.
5- There were 7 different genotypes of the S polymorphic system, 3 of
them were homozygous (S1S1, U1 U1, UI UI), 3 heterozygous (S1 U1],
UI] , S1U1) and the remaining class produced no detectable product on blood typing test. The first, second and seventh classes were the most frequent (38-7, 25.7 and 23.4%), respectively. Mean while, the frequency distribution of each of the remaining classes varied from 1.8 to 6.5%.
6- The complex B polymorphic system was found containing 17 different
antigenic factors distributed among 38 different genotypes in the experimental herd. The C/ antigenic factor occurred most frequently
(0.208) followed by the E/1 antigenic factor (0.182) and the D/ (0.125),
meanwhile, the least frequent one was the G/(0.005).
7- Tbe C polymorpbic system contained only 7 different antigenic factors namely; C2, W1X2, E,X1,LI and R/, distributed in 19 different combinations. Tbe first four factors were tbe most frequent sbowing
values of 0.295, 0.255, 0.229 and 0.179 for frequencies of genes, respectively. Summation of the remaining factors did not exceed 0.0606. Percentage of bomozygosity of the C-antigenic factors was about 20% in the present study.
8- No significant differences were observed for any of tbe productive and reproductive traits studied among tbe different 8 polymorpbic
systems. However the presence of both J and S systems was associated with superior total gain from birth to weaning and J system was associated with slightly superior milk yield as well as the longest calving interval.
9- The preweaning growth performance was not significantly affected by the antigenic factors. However, weaning weight was slightly superior in heifers with the FF genotype. Combination of both UI and U/I had favourable effect on average birth weight.
10- There were actual wide variations in the average daily gain among the various genotypes of the B polymorphic system, which could be used as a good base for genetic selection particularly for such untabulated data. However, such finding needs further studies on a greater number of animals.
II-Homozygous genotypes of the C polymorphic system tended to have superior birth weight as compared to heterozygous. However, EE type showed an opposite trend. C2 factor plays a favourable effect on weaning weight.
12- The 90-D milk yield was significantly inferior (P<0.05) in the presence of LL alleles as compared to the L negative alleles. The M system showed a similar but insignificant trend, and A and J factors showed an opposite trend.The 305-D milk yield did not significantly differ he tween the active and negative al/eles of the A,L,M and J systems, respectively. The main effect was quite similar to that maintained above for 90-D milk yield, but being not significant.
13- The L antigen, had a significant effect on length of lactation period it shortened this period, when L antigen was active.
14-FV antigens did not significantly affect 90-D yield, however,VV genotype was superior in this concept. 305-D yield was superior in the
presence of FF genotype with the longest lactation period.
I5-The main effect of S,B and C antigenic factors an milk yield traits was insignificant.
16- Fat percent was significantly affected by the antigenic factors of the C, FV (P<0.0l) and S systems (P<0.05).
17 -Milk protein was significantly affected by the antigenic factors of the B system only (P<0.01). Similarly the milk lactose. It was also affected by the FV system (P<0.05).
18- The antigenic factors ofthe B,C and FV polymorphic systems signifi-
cantly affected the total solids percent (P<0.0l).
19- The solids not fat percent was significantly (P<0.0I or 0.05)affected by all the antigenic factors under consideration except those of the Land M polymorphic systems.
20- The antigens significantly affected the age at first calving (P<0.05) and that at second calving as well as calving interval (P<0.01), meanwhile, the antigens of the L system significantly affected the days open (P<0.05) other wise, nonsignificant effect was found due to the other antigens under consideration.
It could be concluded from the undergoing results that the blood group alleles proved significant and substantial association with any of the productive and reproductive traits under consideration could be used as a useful marker for improvement and selection of such economical traits. This pattern seems to be more beneficial for early prediction of such traits in the early life of the animals.
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