Analysis of Association of Two Snp in Cholecystokinin B Receptor Gene with Behaviour Scores in German Angus and German Simmental Cattle (brief Report) Assoziationsanalyse Zweier Snp Im Cholecystokininrezeptor B Gen Mit Verhaltensmerkmalen Bei Deutsche Angus Und Deutsches Fleckvieh (brief Report)

Abstract. Behaviour including temperament of cattle especially suckler cows is important for the safety of stockmen and animals. The temperament of cattle can be defined as the answer to human handling situations (BURROW 1997) and can be measured for calves in different tests like tethering test, weighing test or separation- and restraint test (TULLOH 1961, BOISSY and BOUISSOU 1988, LE NEINDRE et al. 1995). The heritabilities for behaviour-traits ranged from 0.02 to 0.33 (GAULY et al. 2002). In this study the cholecystokinin B receptor gene is analysed. This candidate gene is important in the regulation of anxiety in rats (WANG et al. 2005) and in humans (HOSING et al. 2004). In different tests with CCKBR-knockout mice they show more exploratory activity than the wild type mice (RAUD et al. 2003) and less anxious behaviour (HORINOUCHI et al. 2004).


Background
Behaviour including temperament of cattle especially suckler cows is important for the safety of stockmen and animals.The temperament of cattle can be defined as the answer to human handling situations (BURROW 1997) and can be measured for calves in different tests like tethering test, weighing test or separation-and restraint test (TULLOH 1961, BOISSY and BOUISSOU 1988, LE NEINDRE et al. 1995).The heritabilities for behaviour-traits ranged from 0.02 to 0.33 (GAULY et al. 2002).In this study the cholecystokinin B receptor gene is analysed.This candidate gene is important in the regulation of anxiety in rats (WANG et al. 2005) and in humans (HöSING et al. 2004).In different tests with CCKBR-knockout mice they show more exploratory activity than the wild type mice (RAUD et al. 2003) and less anxious behaviour (HORINOUCHI et al. 2004).

Phenotypes
German Angus (GA) and German Simmental (GS) calves were evaluated in three behaviour tests as mentioned within background.In total 962 calves of six GA-sires (545 calves) and eight GS-sires (417 calves) born in four consecutive years were included.Four scores were distributed in the three behaviour tests: one for tethering test (TT, three weeks of age), one for separation-and restraint test (ST, seven to eight month of age) and two for the weighing test at three month of age.The first score for weighing test was given while entering the scale (WT1) and the second during weighing process (WT2).All scores ranged from 1=docile, calm to 5=very excited and were nearly normally distributed with a left tendency.

Statistical analyses
Association analyses between genotypes at the SNPs and behaviour scores were done within breeds using a variance analysis including sex and genotype as fixed effects, age at test as covariate and sire and residual as random effects.Furthermore the allele frequencies for the SNPs between animals with extreme scores (1 versus 4+5) were compared using the chi 2 -test procedures.

Results and discussion
Compared to GenBank NW_001493314 the SNP in intron 3 is at position 311 275 and the other one in the 3'UTR at position 309 831.In the case of allele C in intron 3 the binding site for transcription factor MZF1 (myeloid zinc finger 1) is completed.The genotype-and allelefrequencies for these SNP in the calves are shown in table 1. Noticeable are the missing of genotype TT in intron 3 and 3'UTR in GS and GA, respectively.The missing TT genotype in GS for intron 3 is expected because all GS sires are homozygous CC.The missing TT genotype in GA for 3'UTR can be explained by the low frequency of the T-allele in GA.Only one of the six GA-sires is heterozygous, while the others are homozygous CC.Only the SNP in intron 3 in GA is not in Hardy-Weinberg-equilibrium.With the chi 2 -test procedure only an influence by the intron 3 SNP on score WT2 in GA could be detected with a P-value of 0.0431.In addition a higher frequency of allele C in score 5 than in score 1 was seen.This result could not be verified with the variance analysis and also no association was detected for the 3'UTR SNP.In humans there are several studies about different SNPs and their influence on behaviour (TACHIKAWA et al. 1999, HATTORI et al. 2001, HöSING et al. 2004).So in cattle the sequencing of the whole gene should follow giving the chance to detect more mutations with possible influence on behaviour.

Table 1
Genotype-and allele-frequencies of both SNPs in CCKBR separated by German Angus (GA) and German