Genetic Resistance to Leukaemia in Black-and-White Cattle

Przytulski T., B. Bartoszewicz, H. Kamieniecki, A. Kaw~cki, A. Klemke, L. Niemyska, W. Belec: Genetic Resistance to Leukaemia in Black-and-White Cattle. Acta vet. Brno, 50, 1981: 61-66. Data obtained from 1312 Black-and-White cows of 75 bulls from different farms shows that bulls transmitted different levels of resistance or susceptibility to leu­ kaemia to their daughters. It can be used in practice for early elimination of bulls which are genetically predisposed to leukaemia. The h 2 of leukaemia resistance was 0.13. Relationship between blood groups, transferrins, postalbumins, amylase, xCn, cc.,-Cn, {J-Cn (caseins) and {J-Lg phenotypes and leukaemia was also analyzed. In cows secreting xCn AA types there is a significantly lower incidence of leukae­ mia than in cows producing xCn BB or AB types. The frequency of Y2D'G'1' allele in cows with leukaemia was very high. The differences for the other phenotypes were not significant. Resistance, leukaemia, cattle, polymorphism. Leukaemia is a major animal disease. A significant percentage of domestic and wildlife animal <cases was described by Engelbreth - Holm (1942) and Wiesner (1967). Hereditary predispo­ sition to disease is transmitted according to monogenic mode with three pairs of alleles, the suscep­ tibility to different forms is thought to be due to dominant ones (Gotze and Ziegenhagen 1953; Bottger 1954). Very extensive work on this subject has been carried out by Ernst and his coworkers. They "found (Ernst et al. 1973a, 1974) that the percentage of progeny (daughters) with positive results from matings between susceptible sires and dams was high (14.2 %). The percentage of daughters with positive results of leukaemic test from matings between resistant sires and dams was small (6.3 %). The h2 of differences in predisposition to bovine leukaemia is estimated to be 0.1622. These results were obtained from population of about 50 000 cows. The workers suggested that 1:hese should be taken into account in selection for lower incidence of bovine leukaemia. Prior to the report of Ernst et al. (1973b) little was known concerning any of the genetic mar­ kers of resistance to leukaemia in cattle. In the Brown Latvian cattle, these workers demonstrated that the frequency of antigens B, 1;'., D', P' were about 5-12 % lower and the frequency of antigens C, S, U were about 3 -11 % higher in animals with leukaemia (n = 2495). In addition, in the same breed (36 245 cows) Karlikov et al. (1978) demonstrated that animals which are carriers of the allele BIP' have a significantly lower incidence of leukaemia than cows with other blood group genes. These findings led to the suggestion that it seems possible to per­ i'orm the selective breeding of BIP' bulls in order to decrease the incidence of bovine leukosis. Klimov et al. (1974) indicated that there is in cows of Black-and-White, Red Steppe and Ayrshire breeds with Tf DD, Tf AA and Tf EE phenotypes a significantly higher incidence of leukaemia than in cows with the other phenotypes. These results were not entirely in agreement with those of J 0 0 mk 0 vet al. (1978). They analyzed the relationship between phenotypes of transfer­ rins, ceruloplasmins, amylase and carbonic anhydrase and incidence of leukaemia in Black-and-Whi1:e cattle and found that the frequency of Tf A or Tf AA allele or phenotypes increases in leukae

Leukaemia is a major animal disease.A significant percentage of domestic and wildlife animal <cases was described by Engelbreth -Holm (1942) and Wiesner (1967).Hereditary predisposition to disease is transmitted according to monogenic mode with three pairs of alleles, the susceptibility to different forms is thought to be due to dominant ones (Gotze and Ziegenhagen 1953;Bottger 1954).
Very extensive work on this subject has been carried out by Ernst and his coworkers.They "found (Ernst et al. 1973a(Ernst et al. , 1974) ) that the percentage of progeny (daughters) with positive results from matings between susceptible sires and dams was high (14.2%).The percentage of daughters with positive results of leukaemic test from matings between resistant sires and dams was small (6.3 %).The h 2 of differences in predisposition to bovine leukaemia is estimated to be 0.1622.These results were obtained from population of about 50 000 cows.The workers suggested that 1:hese should be taken into account in selection for lower incidence of bovine leukaemia.
Prior to the report of Ernst et al. (1973b) little was known concerning any of the genetic markers of resistance to leukaemia in cattle.In the Brown Latvian cattle, these workers demonstrated that the frequency of antigens B, 1;'., D', P' were about 5-12 % lower and the frequency of antigens C, S, U were about 3 -11 % higher in animals with leukaemia (n = 2495).
In addition, in the same breed (36 245 cows) Karlikov et al. (1978) demonstrated that animals which are carriers of the allele BIP' have a significantly lower incidence of leukaemia than cows with other blood group genes.These findings led to the suggestion that it seems possible to peri'orm the selective breeding of BIP' bulls in order to decrease the incidence of bovine leukosis.Klimov et al. (1974) indicated that there is in cows of Black-and-White, Red Steppe and Ayrshire breeds with Tf DD, Tf AA and Tf EE phenotypes a significantly higher incidence of leukaemia than in cows with the other phenotypes.These results were not entirely in agreement with those of J 0 0 mk 0 vet al. (1978).They analyzed the relationship between phenotypes of transferrins, ceruloplasmins, amylase and carbonic anhydrase and incidence of leukaemia in Black-and-Whi-1:e cattle and found that the frequency of Tf A or Tf AA allele or phenotypes increases in leukae-mic cows.On the other hand, according to Bussol and Meshcheryakov (1978) the relationship between Tf and Hb phenotypes and incidence of leukaemia in Black-and-White cows was not significant.
The current studies are an attempt to obtain differences in the transmitting ability of resistance and susceptibility to leukaemia in sires and to find differences in haematological diagnosis of leukaemia according to the blood groups and phenotypes of blood serum and milk proteins and enzymes in cows.

Materials and Methods
Leukaemia was diagnosed according to the key by the Veterinary Hygiene Research Station.The whole population was tested twice: at the beginning and at the end of a six-months period.The Black-and-White cows were taken from different farms.The total data included 1312 daughters of 75 sires.The whole population was naturally exposed to the pathogen.
Taking as a criterion the percentage of daughters with positive results, the sires were divided into three groups: Group The percentage of sires' daughters with positive results I ~~ II _ 49-21 III :s;; 20 Only sires with five or more daughters were used.The h 2 of leukaemia resistance was calculated by half-sib correlation (Cochran 1943;Lusch et al. 1948).
The whole population of daughters was divided into two groups.Cows with negative results. to the leukaemic test were placed in group I, cows with positive results formed group II.
In order to ascertain an eventual association between the blood group systems and leukaemia morbidity, both groups were characterized in respect of the gene frequencies in blood group system B, FV, J, L, M, Z and blood red cell antigens of A, C and SU systems.The blood group examinations were carried out according to generally accepted methods.The serum set test was: used enabling identification of 40 following blood red cell antigens: A., H, B1, B., G 2, K, In I., 0" Ox, P, Q, T" Y2' A', B', D', G', 1',0', E;, E;, G;', G;', P', C., R" WI' X., L', F, V, J~ L, M, S, U, H', U', Z.
The gene frequency in biallelic systems was determined by calculating the Chi square root of the recessive alleles frequency.However, in the Band FV systems, the direct counting of particular alleles was used.Genotypes in those systems were determined on the basis of the heredity analysis.and phenotype interpretation.
The results were statistically analyzed by the Chi square method.

Results
The percentage of sire's daughters with leukaemia are presented in Table 1.The highest percentage of progeny with positive results was in group I (60.00).The percentage of daughters with positive results in group III was low (12.50).
The differences between groups were highly significant (P < 0.001).
It may be legitimate to suggest that sires and their daughters were susceptible (I) or resistant (III).
The h 2 ofleukaemia resistance was 0.13 for half-sib by sires.In the group system B an occurrence has been stated of 60 alleles in group I of cows and 45 alleles in group II (Table 2).Both the sum of B alleles occurring with the frequency higher than 1 % and the homozygosity degree in both studied G" B -alleles 1----------------------------

No. of cows
Total number of B -alleles Number of B -alleles of a frequency higher than 1 % Sum of alleles of a frequency higher than 1 % Heterozygosity degree  2).Analysing the frequency of particular B alleles in the groups a statistically significant difference (P < 0.05) was found for Y2D'G'I' allele, which occurred in I group with the frequency of 3.60 % and in group II of cows with the frequency of 6.42 % (Table 2).In the other blood groups systems there were no statistical differences stated (P <0.05).
In the population studied, five phenotypes of Tf (AA, DD, AD, AE, DE), three phenotypes of Poa (FF, FS, SS), three phenotypes of Am I (BB, BC, CC), two phenotypes of IZs.-Cn and (J-Cn (BB, BC and AA, AB, respectively) and three phenotypes of x-Cn and (J-Lg (AA, AB and BB) were found.A significant difference between groups of cows was only found for x-Cn phenotypes (Table 3).
The animals possesing x-Cn AA types a significantly lower (P < 0.10) incidence of leukaemic infection than in cows producing x-Cn BB or AB types.
The effect of allele combination in the two groups of cows has only shown a significant difference in the frequency of Am BB x Poa FF combinations of loci.In the group of cows with negative results the frequencies of Am BB + Poa FF phenotypes was higher in comparison with frequencies of this combinations of loci in group of cows with positive results of leukaemic test.
Generally speaking resistance to infectious disease is more likely to be polygenic than monogenic.It is greatly influenced by the severity of exposure to the pathogen (virulence, dosage) and environmental stress (Hutt 1958(Hutt , 1974(Hutt , 1975;;Payne 1973;Bradley and Spooner 1977).In this study determining the type of inheritance of leukaemia resistance was very difficult.On the other hand, the h 2 of leukaemia resistance in bulls was very low (0.13).However, Ernst et al. (1973aErnst et al. ( , 1974) ) found that the h 2 of predisposition to bovine leukaemia was very small (0.1622).On the other hand, Hutt (1975) suggests that from a population of animals, resistant animals can be obtained even though the value of the heritability coefficient is very small.
On the basis of this work, the bulls transmitted different levels of resistance or susceptibility to leukaemia to their daughters.This preliminary investigation ,also indicates the extremely important role which genetic typing of bulls could playas a supplementary measure in the control of leukaemia.It can be in practice used for early elimination of bulls which are predisposed to leukaemic infection.
In the population studied some genetic markers of resistance to leukaemia in cows were found.However, the differences reported are no greater than would be expected by chance.These results are also not entirely in agreement with those of Ernst et al. (1973b), Joomkov et al. (1978), Klimov et al. (1974).
On the basis of these results there were no significant differences in the Tf phenotypes between groups of cows.It was assumed hypothetically that significant difference of Tf DD type could occur in the cows of I and II groups if the statement reported below were taken into consideration.Wiesner (1963) stated that cows which are characterized by the highest milk production are afflicted with leukaemia more than cows having lower milk production.In the author's ()pinion it was caused by higber metabolic rate in cows with high milk production and thus the greater deficiency of mineral and vitamins) occurring in such animals.On the other hand) Ashton et al. (1964)) Kliment (1974), Siracky and Golota (1971), Przytulski (1979) reported that Tf DD cows produced more milk in comparison with cows with other Tf types.
Also) this idea is not borne out by the finding that x-Cn AA cows a significant lower incidence to leukaemia than in cows producing x-Cn BB or AB types.Hovewer) Macha and Miillerova (1979) found that x-Cn AB cows had higher milk yield in comparison to x-Cn BB and AA cows.On the other hand) Klemke (1978)) Przytulski et al. (1979) reported that x-Cn AA cows had higher milk yield than x-Cn AB cows.
It seems likely that the mechanism of the connection of the pathological changes of leukaemia in animals with higher milk production has different character than the relationship between transferrin and x-Cn types and milk yield.

Table 3 I
Relative frequency(%) ABx: Significant at 0.10 level.I groups were very similar (Table