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G Erhardt

Publications and source records attributed to G Erhardt.

At least 19 recordsLinked to original sources
PubMed2007

Joint analysis of the influence of CYP11B1 and DGAT1 genetic variation on milk production, somatic cell score, conformation, reproduction, and productive lifespan in German Holstein cattle.

Recent publications indicate genetic variation in milk production traits on proximal BTA14, which cannot be explained solely with genetic variation in the DGAT1 gene. To elucidate these QTL effects, animals from a German Holstein granddaughter design (18 families, 1,291 sons) were genotyped for CYP11B1 (V30A) and DGAT1 (K232A) polymorphisms. Frequencies of alleles of maternal descent were estimated for CYP11B1(V) (0.776) and DGAT1(K) (0.549). Allele substitution effects (alpha/2) were first calculated for both alleles in separate models and then in a joint model. From the joint analysis, CYP11B1(V) effects on fat content (+0.04%) and protein content (+0.01%) were positive. Effects on milk yield (-82 kg), fat yield (-0.5 kg), and protein yield (-1.9 kg) were negative. Compared with the individual analysis, DGAT1(K) effects on fat content (+0.28%), protein content (+0.06%), and milk yield (-258 kg) were reduced; fat yield (+10.8 kg) was enhanced; and protein yield (-3.8 kg) was reduced. In the joint analysis, allele substitution effects of CYP11B1(V) and DGAT1(K) together explained more of the variation in milk production traits than DGAT1(K) alone. Further significant effects were found for CYP11B1(V) and DGAT1(K) among 6 reproduction traits and 14 conformational traits. These observations indicate a possible negative influence of DGAT1(K) on maternal nonreturn rate, and thus, on length of productive life.

Animals↗
PubMed2006

Analysis of prion protein genotypes in relation to reproduction traits in local and cosmopolitan German sheep breeds.

Due to the genetic determination of susceptibility to scrapie and other forms of transmissible spongiform encephalopathy (TSE) in sheep breeding to the less susceptible prion protein (PrP) genotype ARR/ARR was advanced within EU. In 4961 ewes of nine German sheep breeds (Coburg Fox sheep, Gray Horned Heath sheep, Merinoland sheep, Rhoen sheep, German Blackheaded Mutton sheep, Shropshire, Suffolk, Texel and White East Friesian Milk sheep) representing local and cosmopolitan breeds the reproductive traits number of lambs born, dead (including abortion at the end of pregnancy, stillbirth and death during the first 56 days post natum), weaned and rearing rate at each lambing were recorded and in 1641 of these ewes the PrP genotype was determined. A linear model was used to evaluate associations between PrP genotype and reproduction traits including the effects of PrP genotype (four classes: ewes with two, one and no copy of the ARR allele and with unknown PrP genotype), breed, interaction of PrP genotype and breed, number of lambing, lambing season and stock. Significant associations were only observed between the PrP genotype and the number of dead lambs at each lambing in Shropshire and Merinoland sheep and the rearing rate at each lambing in Shropshire. These significant associations were mainly caused by differences between animals with unknown PrP genotype and animals of the other PrP classes. In conclusion, breeding for TSE resistant sheep will not lead to a reduction in economically important reproduction traits.

Alleles↗
PubMed2006

Heterosis analysis of Haemonchus contortus resistance and production traits in Rhoen sheep, Merino Land sheep and crossbred lambs.

A crossbreeding program was conducted to evaluate the resistance status to Haemonchus contortus in reciprocal crossbred (F(1)) lambs and their Merino Land sheep (Ml) and Rhoen sheep (Rh) purebred counterparts. A total of 406 lambs were included in the study. Faecal egg counts (FEC) and haematocrit values (Hc) of all the lambs were collected 4 and 8 weeks after an artificial infection with H. contortus. FAMACHA scores were given at the same time. Worm counts of all lambs were obtained after slaughtering at 21 weeks of age. The Ml group consistently showed the highest body weights, daily weight gains and best carcass performances, whereas the Rh group showed the lowest results. Most of the body weight parameters in the F(1) group fell intermediately between the Ml and Rh groups, though the heterosis analysis of body weight and carcass parameters showed a tendency to favour the crossbreeding group Rh x Ml. The Rh group showed, on average, the highest FEC and the lowest Hc values compared to the Ml. However, the nematode counts were not significantly different between the pure breeds. In comparison, the worm counts of the Rh x Ml crosses were significantly different from those in the Ml x Rh crosses. A heterosis analysis showed that FEC, Hc and the worm count in the F(1) group favoured the crossbreeding group Rh x Ml. These results suggested that crossbreeding Rh to Ml sheep may be a suitable way of producing lambs with improved resistance to H. contortus infection without any negative effects on production traits.

Animals↗
PubMed2006

An evaluation of genetic diversity indices of the Red Bororo and White Fulani cattle breeds with different molecular markers and their implications for current and future improvement options.

The genetic diversity of the Red Bororo and White Fulani cattle breeds of Cameroon and Nigeria was assessed with a panel of 32 markers. Estimates for the various indices of genetic diversity, total number of alleles (TNA), mean observed number of alleles (MNA), mean effective number of alleles (MNE), observed heterozygosity (Hob) and expected heterozygosity (Hex), were higher at microsatellite loci than at protein loci. Mean Hex values were above 71% at microsatellite loci in all the breeds and ranged from 37% to 41.6% at milk protein loci and from 40.9% to 45.6% at blood protein loci. The highest TNA and MNA of microsatellites were recorded for the Nigerian White Fulani. MNE of milk protein loci was highest in the Cameroonian Red Bororo, while TNA of blood protein loci was highest in the Cameroonian White Fulani. The high genetic diversity levels indicate the presence of the necessary ingredients for improvement breeding and conservation. Multi-locus estimates of within-population inbreeding (f), total inbreeding (F) and population differentiation (theta) of the breeds were significantly different from zero, except for theta of blood proteins. A high level of gene flow was found between the breeds (5.829). The phylogenetic relationship existing among the four breeds is greatly influenced by location. The high gene flow between the breeds may lead to a loss of genetic diversity through genetic uniformity and a reduction in opportunities for future breed development. We propose an improvement scheme with aims to prevent loss of genetic diversity, improve productivity and reduce uncontrolled genetic exchanges between breeds.

Alleles↗
PubMed2006

Mapping of quantitative trait loci for lactation persistency traits in German Holstein dairy cattle.

A whole genome scan to map quantitative trait loci (QTL) for persistency of milk yield (PMY), persistency of fat yield (PFY), persistency of protein yield (PPY) and persistency of milk energy yield (PEY) was performed in a granddaughter design in the German Holstein dairy cattle population. The analysis included 16 paternal half-sib families with a total of 872 bulls. The analysis was carried out for the first lactation and for the first three lactations combined using univariate weighted multimarker regression. Controlling the false discovery rate across traits and data sets at a level of 0.15 and treating the four persistency traits as different traits revealed 27 significant QTL. A total of 12 chromosomes showed significant QTL effects on a chromosomewise basis. The DGAT1 effect was highly significant for PPY and protein yield. A haplotype analysis using results of previous studies of the same design revealed a co-segregation of various persistency QTL and QTL affecting health traits like dystocia and stillbirth and functional traits like non-return rate 90 and somatic cell score.

Animals↗
PubMed2006

Short communication: a polymorphism in ABCG2 in Bos indicus and Bos taurus cattle breeds.

A single nucleotide change (A/C) in exon 14 is capable of encoding a substitution of tyrosine-581 to serine (Y581S) in the ABCG2 (ATP binding cassette, subfamily G, member 2) gene and affects milk production traits. The ABCG2(A) allele decreases milk yield and increases protein and fat concentration. The allele frequencies were determined in 32 Bos taurus and 3 Bos indicus breeds; ABCG2(A) was predominant in all populations. This allele approached fixation in 23 out of 35 breeds, including all 3 Bos indicus breeds. The ABCG2(C) allele was found in the Belgian Blue (beef), Belgian Blue Mix, British Friesian, Bohemian Red, East Anatolian Red, German Angus, German Black Pied, German Brown, German Simmental, Israeli Holstein, Menorquina, and US Holstein breeds. Thus, the genetic gain expected from selection for ABCG2(A) may be limited. The detection of ABCG2(C) only in Bos taurus breeds may indicate that ABCG2(A) is the ancestral allele, and that the Y581S substitution occurred after the separation of the Bos indicus and Bos taurus lineages.

ATP-Binding Cassette Transporters↗
PubMed2006

Influence of sex on the resistance of sheep lambs to an experimental Haemonchus contortus infection.

36 intact male and 69 female lambs of two breeds (n = 63 Merinoland; n = 42 Rhön) aged 12 weeks were orally infected with 5000 infective-stage larvae, L3, of the nematode Haemonchus contortus. After 4 and 8 weeks faecal egg counts (FEC), haematocrit values and plasma testosterone levels were determined. All lambs were slaughtered at 20 weeks of age. The gastrointestinal tracts were examined for the presence of adult stages of H. contortus. Male lambs showed significantly higher log FEC (p < 0.001), higher mean establishment rates (p < 0.05), higher worm burdens (p < 0.01) and lower haematocrit values (p < 0.001) when compared with female lambs. Correlations between economically important traits (body weight, daily weight gain) and parasitological parameters were significantly higher in male animals. Testosterone level was 4 weeks after infection significantly positive correlated with worm burden. The results suggest that female lambs are more resistant against an experimental H. contortus infection when compared with male lambs. Testosterone seems to play an important role in resistance. This approach can be of importance if parasite resistance is incorporated into breeding programs and the estimated breeding values for rams are only based on male offspring information. Therefore male breeding values are probably not representative for the whole population.

Animals↗
PubMed2005

Age-related differences of Ascaridia galli egg output and worm burden in chickens following a single dose infection.

Ninety white chickens (Lohmann LSL) were reared under helminth-free conditions and divided into five groups. Four groups were artificially infected with 250 embryonated Ascaridia galli eggs at the age of 6, 12, 18 or 24 weeks. Ten birds were kept as uninfected controls. Six and 10 weeks after infection (p.i.), individual faecal egg counts (FEC) were performed. The birds were slaughtered after the second sampling and their gastrointestinal tracts were examined for the presence of adult A. galli. The FEC increased from the first to the second sampling significantly in all the infected groups. The highest increase was shown in the group infected at 12 weeks of age, whereas the increase in the other groups was relatively moderate. However, the total worm burden and mean FEC at the second sampling were highest (p<0.01) in those birds infected at an age of 12 or 18 weeks. The serum protein and triiodothyronine (T3) levels did not differ significantly (p>0.05) between any of the groups. Thyroxine (T4) was significantly different between the groups infected at 6 and 18 weeks of age (p<0.05), and those at 6 and 24 weeks of age (p<0.01). The thyroid hormone levels correlated significantly with the FEC. Age does not seem to play a major role in resistance to A. galli infections in layers, whereas a bird's hormonal and immune status, related to laying activity, seems to have a significant negative impact on resistance.

Age Factors↗
PubMed2005

Genetic structure and differentiation of 12 African Bos indicus and Bos taurus cattle breeds, inferred from protein and microsatellite polymorphisms.

Level of genetic differentiation, gene flow and genetic structuring of nine Bos indicus and three Bos taurus cattle breeds in Cameroon and Nigeria were estimated using the genetic information from 16 microsatellite, five blood protein and seven milk protein markers. The global heterozygote deficit across all populations (Fit) amounted to 11.7% (p < 0.001). The overall significant (p < 0.001) deficit of heterozygotes because of inbreeding within breeds (Fis) amounted to 6.1%. The breeds were moderately differentiated (Fst = 6%, p < 0.001) with all loci except CSN1S2 contributing significantly to the Fst value. The 12 populations belong to two genetic clusters, a zebu and a taurine cluster. While inferred sub-clusters within the taurine group corresponded extremely well to predefined breed categorizations, no real sub-clusters, corresponding to predefined breeds, existed within the zebu cluster. With the application of prior population information, cluster analysis achieved posterior probabilities from 0.962 to 0.994 of correctly assigning individuals to their rightful populations. High gene flow was evident between the zebu populations. Positive and negative implications of the observed genetic structure of the breeds on their development, improvement and conservation are discussed. The study shows that the breeds are threatened by uncontrolled breeding and therefore are at risk to become genetically uniform in the future. This situation can be avoided by putting in place effective breeding and management measures aimed at limiting uncontrolled mating between the breeds and to preserve special characteristics, genetic as well as breed biodiversity. The first step towards realizing these goals might be to geographically demarcate the breeds.

Animals↗
PubMed2005

Strain typing of German transmissible spongiform encephalopathies field cases in small ruminants by biochemical methods.

Following the implementation of a large scale transmissible spongiform encephalopathies (TSE) surveillance programme of small ruminants, evidence for a natural transmission of bovine spongiform encephalopathy (BSE) to a French goat has been found. During the years 2002-2004, a massive TSE rapid testing programme on >250,000 small ruminants was carried out in Germany. In this national survey, 186 scrapie-affected sheep were found which originated from 78 flocks. The majority of these cases were of the classical TSE type (115 sheep belonging to 14 outbreaks). However, 71 cases coming from 64 flocks were of the novel atypical scrapie type. According to the regulation EU 999/2001, all TSE cases in small ruminants have to be examined by strain typing methods to explore any possibility of the existence of BSE cases in the field sheep population. Here we report on a biochemical typing strategy (termed FLI-test), which includes the determination of molecular masses, antibody binding affinities and glycosylation pattern of the TSE induced abnormal prion protein. Based on this typing approach none of the analysed German classical TSE outbreaks (total number of analysed sheep: 36) displayed biochemical features indicative for a BSE infection. However, in two cases distinct but BSE-unrelated PrP(Sc) types were found, which alludes to the existence of different scrapie strains in the German sheep population.

Animals↗
PubMed2005

Caprine kappa-casein (CSN3) polymorphism: new developments in molecular knowledge.

A high degree of polymorphism was recently found at the kappa-casein (CSN3) locus in the domesticated goat (Capra hircus). In the present study, 2 new patterns previously identified by PCR-single-strand conformation polymorphism analysis (SSCP) were characterized. The allele provisionally named "X" (GenBank Accession no. AY350425) differs from CSN3*C (AF485341) by a (silent) A-->G substitution at position 509 of the goat CSN3 reference sequence (X60763). As this newly identified sequence changes the amino acid sequence, and the already known CSN3*C allele (AF485341) has an additional silent mutation, we proposed a change in nomenclature to reflect these changes, indicating the silent mutation with the prime symbol (i.e.,'). The CSN3*M allele (provisionally named "Y") results in a new protein variant, differing by 2 nonsynonymous mutations from the CSN3*F allele. The new variant is characterized by a G-->A transition at nucleotide position 384, resulting in the amino acid exchange Asp90-->Asn90, and a C-->T transition at position 550, resulting in a Val145-->Ala145 substitution. Thus, the number of alleles identified in the domesticated goat has increased to 16, of which 13 are protein variants and 3 are silent mutations, involving a total of 15 polymorphic sites in CSN3 exon 4. Data on the distribution of the main alleles in 7 goat breeds of Europe, West Africa, and the Near East show differences in the occurrence and frequency of the alleles between breeds and geographic origin with the highest number of alleles found in goat breeds from the Near East.

Alleles↗
PubMed2004

Prion protein allele A136 H154Q171 is associated with high susceptibility to scrapie in purebred and crossbred German Merinoland sheep.

Prion protein (PrP) genotypes were determined in eight sheep that have been tested positive for atypical scrapie from purebred or crossbred Merinoland sheep flocks in Germany and compared with the PrP genotypes of their flock mates. Two restriction fragment length polymorphism (RFLP) analyses were developed to determine all PRNP haplotypes occurring by variations at codons 136, 154 and 171. At least one copy of the A(136) H(154) Q(171) (AHQ) allele was found in all scrapie-positive sheep while the frequency of AHQ varied from over 23% to less than 3% in the whole flocks. There was a significant association between PrP genotype and a positive scrapie diagnosis over all flocks, suggesting a high scrapie susceptibility of PrP genotypes including the AHQ allele, at least in sheep of Merinoland type. These results argue that sheep with the AHQ allele are not generally less susceptible to scrapie and support the hypothesis that the influence of this allele on scrapie susceptibility may vary from flock to flock depending on genetic and/or epidemiological factors. This has to be considered when strategies for the eradication of scrapie in sheep are based on PrP genotypes.

Alleles↗
PubMed2004

Atypical scrapie cases in Germany and France are identified by discrepant reaction patterns in BSE rapid tests.

The intensified surveillance of scrapie in small ruminants in the European Union (EU) has resulted in a substantial increase of the number of diagnosed cases. Four rapid tests which have passed the EU evaluation for BSE testing of cattle are also recommended currently and used for the testing of small ruminants by the EU authorities. These tests include an indirect ELISA (cELISA), a colorimetric sandwich ELISA (sELISA I), a chemiluminescent sandwich ELISA (sELISA II), and a Western blot (WB). To this point, the majority of samples have been screened by using either sELISA I (predominantly in Germany) or WB (predominantly in France). In this study, it is shown that a number of the German and French scrapie cases show inconsistent results using rapid and confirmatory test methods. Forty-eight German sheep, 209 French sheep and 19 French goat transmissible spongiform encephalopathy (TSE) cases were tested. All cases were recognised by the sELISA I and either one of the confirmatory methods (scrapie-associated fibrils (SAF)-immunoblot or immunohistochemistry). Surprisingly, three rapid tests failed to detect a significant number of scrapie cases (29 in France and 24 in Germany). The possible reasons for these inconsistent reaction patterns of scrapie cases are discussed. Similar discrepancies have not been observed during rapid testing of cattle for BSE, the disease for which all diagnostic methods applied have been evaluated.

Animals↗
PubMed2004

Polymorphisms in blood proteins of Bos indicus and Bos taurus cattle breeds of Cameroon and Nigeria, and description of new albumin variants.

Polymorphisms in the five blood protein loci albumin (ALB), carbonic anhydrase (CA II), vitamin D binding protein (GC), haemoglobin (HBB), and transferrin (TF) were investigated in 520 individuals from 12 cattle populations (Bos indicus and Bos taurus) in Cameroon and Nigeria by isoelectric focusing with carrier ampholytes in ultrathin polyacrylamide gels (PAG-IEF) and by linear gradient polyacrylamide gel electrophoresis (PAGE). While all loci in nine populations were polymorphic with up to six alleles at the ALB and TF loci: the Namchi population showed monomorphism at the CA II locus and Muturu at the ALB, CA II, and HBB loci. There was a clear distinction between Bos indicus and Bos taurus breeds at the ALB locus with ALBB predominating in indicine and ALBA predominating in taurtine breeds. CA IIS, GCA, and HBBA were the most commonly occurring alleles in all populations. Two variants not described before were demonstrated by PAG-IEF at the ALB locus and named ALBJ and ALBK. Mean effective number of alleles as measure of intrabreed diversity was higher in zebu populations (2.040-2.288) as compared to taurine breeds (1.349-1.836). Significant deviations from Hardy-Weinberg equilibrium occurred in some populations at the HBB and TF loci. More haplotypes of ALB/GC occurred in the zebu than taurine breeds. ALBAGCA predominated in the taurine populations and ALBBGCA in the indicine populations. Influence of zebu genes on the Namchi and N'Dama taurine breeds was detected at the ALB, CA II, HBB, and TF loci, and estimated at 61.5% and 5.7%, respectively. The high resolution of PAG-IEF in screening for polymorphisms within diversity studies was demonstrated.

Albumins↗
PubMed2004

Neuronal accumulation of abnormal prion protein in sheep carrying a scrapie-resistant genotype (PrPARR/ARR).

The susceptibility of sheep to scrapie infection is influenced by prion gene alleles, which are modulated by polymorphic variations corresponding to amino acid positions 136, 154 and 173 of the prion protein (PrP). As no unquestioned report of a diseased sheep carrying homozygous alleles encoding alanine, arginine and arginine (PrPARR) at these sites has been published to date, sheep of this genotype are believed to be scrapie resistant. After the introduction of large-scale rapid testing for scrapie, a number of so-called 'atypical' scrapie cases have been found in Germany and elsewhere. Among those cases were two supposedly scrapie-resistant sheep. Brain samples from these animals tested positive for abnormal PrP (PrPSc) in one of four rapid tests available. Moreover, scrapie-associated fibril (SAF)-immunoblotting and immunohistochemistry, which are the generally accepted diagnostic techniques for scrapie, revealed prominent PrPSc deposition in the cerebellum. SAF immunoblotting also revealed PrPSc deposition in the obex, frontal cortex and brainstem. Transmission experiments to investigate the infectivity of scrapie propagated from these sheep have been initiated.

Alanine↗