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At least 739 records · Page 41Linked to original sources
PubMed1984

[Analysis of factors affecting the electric conductivity of cow's milk--breed, locale, season].

The problem was studied in a set of 678 mammary glands of 212 cows - crossbreds between the Holstein-Friesian breed with the Slovak Spotted cattle, crossbreds of the Black-Pied Lowland and Bohemian Spotted breed, and three-way crossbreds of the Black-Pied Lowland, Swedish White and Bohemian Spotted cattle. The confrontation of the confidence intervals of milk conductivity (MC) in healthy mammary glands at alpha = 0.05 showed that in the crossbreds of the Black-Pied Lowland cattle the MC was statistically significantly higher than in the breed types of the Holstein-Friesian cattle. The MC values decrease when there is a larger proportion of the blood of beef-and-dairy cattle (Slovak Spotted and Bohemian Spotted breeds). The locality where the stock was kept was found to act as an important factor underlying MC only in cases when both the geographical conditions and breed proportions were different. In a set homogenized with respect to the breeds, statistically significant differences in MC were demonstrated between the spring and summer season, spring and autumn, summer and autumn, and autumn and winter season.

Animals↗
PubMed1982

Variation in age at death of dogs of different sexes and breeds.

A retrospective study of necropsy data for 2,002 dogs showed that the mean age at death of neutered dogs of both sexes exceeded that of intact dogs, but the differences were not significant. A wide variation in mean age at death of 56 breeds and cross breeds, 3.0 to 9.9 years, was found. This variation was not correlated with mean breed body weight. An attempt was made to explain the variability by finding diseases to which dogs of the short-lived breeds were particularly susceptible. This was not possible in general, since the samples of each breed were small and the total number of diseases from which they died so large. Dogs of long-lived breeds died of diseases appropriate to their age, particularly cancer, 39% of the sample. In the sample as a whole, cancer accounted for 20% of deaths at 5 years and increased to and remained between 40% and 50% from 10 to 16 years of age.

Age Factors↗
PubMed1978

[Difference in susceptibility to mastitis between the Dutch-Friesian and Meuse-Rhine-Yssel breeds of cattle (author's transl)].

A randomized study in the Netherlands showed that symptoms of mastitis were more common in animals of the Meuse-Rhine-Yssel breed than they were in those of the Dutch-Friesian breed. The samples were taken at random from large groups of animals (approximately 10,000) of the dairy cattle population in the Netherlands, quarter samples being examined for the presence of the causative organisms of mastitis and cell counts being made. Differences between the two breeds were also observed in herds on the experimental farm "'t Gen" on which the animals were reared and kept in the same environment. Therefore, there is some justification in defining these differences as genetic. The results of the studies suggest that a group of animals showing lower cell counts during the first lactation will be less susceptible to mastitis. Studies in a cow-house of the Central Veterinary Institute revealed a significant difference in increase of the cell count between animals of the Dutch-Friesian breed and those of the Meuse-Rhine-Yssel breed following intramammary injection of a staphylococcal beta toxin. Further analysis of the results of the randomized study showed that differences in susceptibility to mastitis do not become plainly apparent until later in life. In view of the results of these studies, it would seem advisable to pay more attention to differences in susceptibility to mastitis in stock-breeding.

Age Factors↗
PubMed1995

[Genetic divergence of certain indigenous and commercial breeds of Eurasian cattle (Bos taurus)].

The genetic distances between cattle breeds were calculated and relationships between these breeds were analyzed on the basis of polymorphism of genes encoding seven blood proteins (N = 22 breeds) and four milk proteins (N = 14 breeds). The study was performed using cluster and cladistic analysis, as well as multidimensional scaling. The conventional systems of classification of cattle breeds are reviewed in genetic terms, and the history of breeds and their evolution are discussed.

Animals↗
PubMed1995

Public service deficiencies and Aedes aegypti breeding sites in Venezuela.

The 1992 study reported here assessed relationships between potable water supply and trash collection practices and the prevalence of dengue vector mosquito (Aedes aegypti) breeding sites in 30 towns located along the north coast of Venezuela. Within each study town, 100 homes were chosen. At each of these homes the number of water-bearing containers and containers harboring A. aegypti were determined and interviews were conducted to obtain information about the local water supply, trash collection services, and excreta disposal. In general, A. aegypti breeding indexes were high: 55% of the residences were found to harbor A. aegypti immature forms; there was an average of 118 breeding sites per 100 residences; and 24% of the water-bearing receptacles were observed to contain the mosquito. The statistical method of principal component analysis was employed to rank the 30 towns in terms of variables describing public service deficiencies, and correlations existing between the variables studied were determined. Direct correlations were found between two water supply variables (frequency and duration of water supply interruptions), between the excreta disposal and trash collection variables, between the duration of water supply interruptions and the Aedes breeding indexes, and between the duration of water supply interruptions and the mean number of A. aegypti breeding sites found in water storage containers. Overall, the towns with the poorest services were found to have the highest breeding indexes and the greatest numbers of water storage containers harboring the mosquito. It is concluded that public service (water supply and waste disposal) deficiencies were largely responsible for A. aegypti propagation in the study towns. Accordingly, it is recommended that local programs be implemented for recycling containers, constructing water storage tanks that cannot harbor Aedes larvae, and conducting health education and community participation campaigns directed against the mosquito.

Aedes↗
PubMed1998

Urolithiasis in dogs. IV: Survey of interrelations among breed, mineral composition, and anatomic location of calculi, and presence of urinary tract infection.

OBJECTIVE: To compile and analyze selected data from a large number of canine urinary calculus specimens that were subjected to quantitative, layer-by-layer mineral analysis. SAMPLE POPULATION: 11,000 canine urinary calculus specimens: 5,781 from female dogs, 5,215 from male dogs, and 4 from dogs of unrecorded sex. PROCEDURE: Records of the Urinary Stone Analysis Laboratory, School of Veterinary Medicine, University of California were used to compile information regarding urinary calculus specimens from dogs. Records surveyed were of all canine calculi submitted for analysis between July 1981 and January 1994. Results analyzed included those of a mixed-breed group and 26 common breeds of stone-forming dogs. Interrelations of breed, sex, and age of the affected dogs, mineral composition of the specimens, and associated urinary tract infections were analyzed statistically. RESULTS: Proportions of culture-positive specimens were significantly correlated between the sexes (r = 0.494, P = 0.008). Staphylococcus intermedius was isolated most often from either sex, ranging from 36.1% (Basset Hounds) to 67.9% (Pekingese) of cultured specimens from females and 8.7% (Chihuahuas) to 71.4% (Scottish Terriers) of specimens from males. The second most frequently isolated bacterial species, Escherichia coli, ranged from 0% in males of 2 breeds and females of 4 breeds to 25% in Cairn Terrier males and 19.4% in Basset Hound females. Streptococcus spp were the third most frequently isolated bacterial species. Significant correlations between the sexes were found for percentages of calculi located in the urinary bladder (r = 0.490, P = 0.008), and for calculi voided in the urine (r = 0.503, P = 0.006). CONCLUSIONS: Breed and sex differences in prevalence of urolithiasis- and mineral-associated bacterial infections are numerous. Staphylococcus intermedius was the most common isolate from specimens from all but 3 of 54 breed/sex groupings. For either sex, streptococcal infections were significantly related to proportions of calculi passed in the urine.

Age Distribution↗
PubMed1976

[2 genetic systems of serum amylase in the Kholmogor breed of cattle].

All the genetic types of amylase I (AmI) and amylase II (AmII) known for the species Bos taurus are encountered in the Kholmogorskaya breed of cattle. Besides the two alleles, AmIB and AmIC found in all the other European breeds of cattle the locus in the Kholmogorskaya breed also includes a rare allele AmI-A hitherto considered to be characteristic only of zebu-like cattle. The frequencies of the alleles AmI-A, AmI-B and AmI-C in the Kholmogorskaya breed proved to be 0.014, 0.392 and 0.594 respectively (n = 1098). Of the two co-dominant alleles, AmII-A and AmII-B controlling the synthesis of the isozymes of the second amylase system the first is rare, occurring with the frequency of 0.131 (n = 245). The earlier assumption of Mazumder and Spooner, that there is no linkage between the genes of the loci AmI and AmII is corroborated. The breeds assigned to the Bos taurus brachyceros type have a lower frequencies of the AmI-C allele as compared to other breeds the origin of which is associated with the subspecies B. t. primigenius.

Alleles↗
PubMed2025

Molecular breeding of tomato: Advances and challenges.

The modern cultivated tomato (Solanum lycopersicum) was domesticated from Solanum pimpinellifolium native to the Andes Mountains of South America through a "two-step domestication" process. It was introduced to Europe in the 16th century and later widely cultivated worldwide. Since the late 19th century, breeders, guided by modern genetics, breeding science, and statistical theory, have improved tomatoes into an important fruit and vegetable crop that serves both fresh consumption and processing needs, satisfying diverse consumer demands. Over the past three decades, advancements in modern crop molecular breeding technologies, represented by molecular marker technology, genome sequencing, and genome editing, have significantly transformed tomato breeding paradigms. This article reviews the research progress in the field of tomato molecular breeding, encompassing genome sequencing of germplasm resources, the identification of functional genes for agronomic traits, and the development of key molecular breeding technologies. Based on these advancements, we also discuss the major challenges and perspectives in this field.

Solanum lycopersicum↗
PubMed1990

Endocrine correlates of hibernation-independent gonadal recrudescence and the limited late-winter breeding season in woodchucks, Marmota monax.

Woodchucks (Marmota monax) normally experience gonadal recrudescence towards the end of a 4-5 month hibernation, emerge in late winter, immediately breed in a short 3-week breeding season, and have regressed gonads before the next hibernation. Our studies of wild and captive animals show that fertile females give birth to single litters after a 32-day gestation and their breeding season is terminated by a reactivation of the corpora lutea of pregnancy for 1-3 months immediately postpartum. In nonbred females the breeding season is likewise terminated by spontaneous luteinization of the ovaries for 1-3 months shortly after the vernal equinox. Tests regress and testosterone declines during and after the breeding season. Circannual reproductive cycles persist in the absence of hibernation and are shortened to 9-10 months after 3-5 years of a 12L:12D photoperiod. Unique aspects of this species that merit endocrine investigation include descent/retraction of testes, transient luteolysis at parturition, superactivation of postpartum corpora lutea, regulation of the pituitary-gonadal axis by an annual endogenous metabolic cycle entrained to the annual change in photoperiod, and the hormonal basis of hibernation.

Animal Husbandry↗
PubMed2005

Wheat genetic diversity trends during domestication and breeding.

It has been claimed that plant breeding reduces genetic diversity in elite germplasm which could seriously jeopardize the continued ability to improve crops. The main objective of this study was to examine the loss of genetic diversity in spring bread wheat during (1) its domestication, (2) the change from traditional landrace cultivars (LCs) to modern breeding varieties, and (3) 50 years of international breeding. We studied 253 CIMMYT or CIMMYT-related modern wheat cultivars, LCs, and Triticum tauschii accessions, the D-genome donor of wheat, with 90 simple sequence repeat (SSR) markers dispersed across the wheat genome. A loss of genetic diversity was observed from T. tauschii to the LCs, and from the LCs to the elite breeding germplasm. Wheat's genetic diversity was narrowed from 1950 to 1989, but was enhanced from 1990 to 1997. Our results indicate that breeders averted the narrowing of the wheat germplasm base and subsequently increased the genetic diversity through the introgression of novel materials. The LCs and T. tauschii contain numerous unique alleles that were absent in modern spring bread wheat cultivars. Consequently, both the LCs and T. tauschii represent useful sources for broadening the genetic base of elite wheat breeding germplasm.

Breeding↗
PubMed2005

Application of a new IBD-based QTL mapping method to common wheat breeding population: analysis of kernel hardness and dough strength.

Mapping quantitative trait loci (QTL) in plants is usually conducted using a population derived from a cross between two inbred lines. The power of such QTL detection and the estimation of the effects highly depend on the choice of the two parental lines. Thus, the QTL found represent only a small part of the genetic architecture and can be of limited economical interest in marker-assisted selection. On the other hand, applied breeding programmes evaluate large numbers of progeny derived from multiple-related crosses for a wide range of agronomic traits. It is assumed that the development of statistical techniques to deal with pedigrees in existing plant populations would increase the relevance and cost effectiveness of QTL mapping in a breeding context. In this study, we applied a two-step IBD-based-variance component method to a real wheat breeding population, composed of 374 F6 lines derived from 80 different parents. Two bread wheat quality related traits were analysed by the method. Results obtained show very close agreement with major genes and QTL already known for those two traits. With this new QTL mapping strategy, inferences about QTL can be drawn across the breeding programme rather than being limited to the sample of progeny from a single cross and thus the use of the detected QTL in assisting breeding would be facilitated.

Breeding↗
PubMed2005

Genetic diversity among alfalfa (Medicago sativa) cultivars coming from a breeding program, using SSR markers.

Alfalfa (Medicago sativa) is an autotetraploid, allogamous and heterozygous species whose cultivars are synthetic populations. The breeders apply selection pressure for some agronomic traits within a breeding pool to increase the frequency of favorable individuals. The objective of this study was to investigate the differentiation level among seven cultivars originating from one breeding program, and between these cultivars and the breeding pool, with eight SSR markers. These highly polymorphic and codominant markers, together with recent population genetic statistics extended to autotetraploids, offer tools to analyse genetic diversity in alfalfa. The number of alleles per locus varied between 3 and 24. All loci were at a panmictic equilibrium in the cultivars, except one, probably because of null alleles. With seven SSR loci, each cultivar was at panmictic equilibrium. The mean gene diversity was high, ranging from 0.665 to 0.717 in the cultivars. The parameter F(ST) indicated a low but significant diversity among cultivars. Among 21 pairs of cultivars, 15 were significantly different. The breeding pool also had a high diversity, and was significantly different from each cultivar except the most recent one. Considering the characteristics of the breeding program and the mode of cultivar elaboration, we found that they were unable to generate a large variety differentiation. Estimation of population genetics parameters at SSR loci can be applied for assessing the differences between cultivars or populations, either for variety distinction or the management of genetic resources.

Breeding↗
PubMed2006

A new test for family-based association mapping with inbred lines from plant breeding programs.

Association mapping holds great promise for the detection of quantitative trait loci (QTL) in plant breeding populations. The main objectives of this study were to (1) adapt the quantitative pedigree disequilibrium test to typical pedigrees of inbred lines produced in plant breeding programs, (2) compare the newly developed quantitative inbred pedigree disequilibrium test (QIPDT) with the commonly employed logistic regression ratio test (LRRT), with respect to the power and type I error rate of QTL detection, and (3) demonstrate the use of the QIPDT by applying it to flowering data of European elite maize inbreds. QIPDT and LRRT were compared based on computer simulations modeling 55 years of hybrid maize breeding in Central Europe. Furthermore, we applied QIPDT to a cross-section of 49 European elite maize inbred lines genotyped with 722 amplified fragment length polymorphism markers and phenotyped in four environments for days to anthesis. Compared to LRRT, the power to detect QTL was higher with QIPDT when using data collected routinely in plant breeding programs. Application of QIPDT to the 49 European maize inbreds resulted in a significant (P < 0.05) association located at a position for which a consensus QTL was detected in a previous study. The results of our study suggested that QIPDT is a promising QTL detection method for data collected routinely in plant breeding programs.

Breeding↗
PubMed2005

Genetic structure of an endangered Portuguese semiferal pony breed, the Garrano.

The present study intends to survey the genetic variability of an endangered semiferal Portuguese native pony breed, the Garrano. Thirteen microsatellite markers were examined in 277 animals born in 1998, belonging to eight subpopulations corresponding to eight northern Portuguese geographic regions. Mean heterozygosity (H(o)) in the Garrano breed was 0.732, ranging from 0.531 to 0.857 across subpopulations. Allelic frequencies and diversity differed significantly between regions, suggesting the existence of genetic differentiation within the breed confirmed by the population differentiation estimator F(ST). Allele sharing genetic distance (Dps) was used to determine the relationship between the analyzed subpopulations, some of which are diverging significantly from the others. Relationships among six Iberian horse breeds (including the Garrano) were assessed through the restricted maximum likelihood method, which clusters the Garrano with another Celtic pony, the Spanish Asturcon, traditionally bred in geographical continuity with the Garrano. Results reveal a statistically significant deficit of heterozygotes within the Garrano breed (F(IT) = 0.031, p < 0.05). Regular monitoring should therefore be implemented so that the effect of genetic drift within subpopulations, enhanced by inbreeding, may be successfully minimized.

Alleles↗
PubMed2004

Cassava breeding: opportunities and challenges.

Although cassava is a major food crop, its scientific breeding began only recently compared with other crops. Significant progress has been achieved, particularly in Asia where cassava is used mainly for industrial processes and no major biotic constraints affect its productivity. Cassava breeding faces several limitations that need to be addressed. The heterozygous nature of the crop and parental lines used to generate new segregating progenies makes it difficult to identify parents with good breeding values. Breeding so far has been mainly based on a mass phenotypic recurrent selection. There is very little knowledge on the inheritance of traits of agronomic relevance. Several approaches have been taken to overcome the constraints in the current methodologies for the genetic improvement of cassava. Evaluations at early stages of selection allow for estimates of general combining ability effect or breeding values of parental lines. Inbreeding by sequential self-pollination facilitates the identification of useful recessive traits, either already present in the Manihot gene pool or induced by mutagenesis.

Breeding↗
PubMed2005

Production objectives and management strategies of livestock keepers in south-east Kenya: implications for a breeding programme.

A survey of pastoralist and agropastoralist households in south-east Kenya was conducted to determine their production objectives and management strategies in order to optimize and extend a breeding programme for indigenous small East African Shorthorn Zebu cattle. The reasons for keeping cattle and the breed/trait preferences identified reflect the multiple objectives of the livestock keepers, with both adaptive traits and productive/reproductive traits rated as important. Although the Maasai and Kamba zebu (M&KZ) breeds were ranked highly with regard to adaptive traits, the population is considered to have been in decline over recent years. In order to promote the conservation and sustainable use of the M&KZ cattle, the formation of an open nucleus breeding scheme is recommended. In particular, such a scheme would be able to address several existing constraints (e.g. individual herds are very small and communal use of pastures/water makes controlled mating difficult). Such interventions would require the full participation of the livestock keepers, as well as ensuring that a holistic approach to species and breed attributes is taken into account in setting breeding goals, such that the full array of contributions that livestock make to livelihoods and the genetic characteristics related to these contributions are fully incorporated into the programme.

Adult↗
PubMed2006

Identification and quantification of subsidies relevant to the production of local and imported pig breeds in Vietnam.

Livestock diversity contributes in many ways to human survival and well-being, while its loss reduces options for attaining sustainable agriculture and universal food security. The current rapid rate of loss of this diversity is the result of a number of underlying factors. While in some cases changes in production systems and consumer preferences reflect the natural evolution of developing economies and markets, in other cases production systems, breed choice and consumer preferences have been distorted by local, national and international policy. In the context of a widespread threat to local pig breeds in Vietnam, this paper identifies and quantifies the level of agricultural subsidies that are currently contributing to this process of breed substitution. Producer subsidies-which tend to improve the competitiveness of imported breeds and their crosses over local breeds--are shown to be considerable, and mitigating measures are now urgently needed to avoid an irreversible loss of livestock diversity.

Animal Husbandry↗
PubMed2026

Effect of founder breeds on genotype imputation accuracy in Canchim cattle.

UNLABELLED: Genotype imputation is a technique used to infer unobserved genotypes based on reference panels, allowing increased marker density and cost-effective optimization for genomic selection. This study aimed to evaluate whether the inclusion of genotypes from the founder breeds Nelore (NE) and Charolais (CH) improves the imputation accuracy in the composite beef cattle breed Canchim (CA). The populations studied consisted of 804 NE, 897 CH, and 392 CA animals, all genotyped using high-density panels (777,962 SNP &#x2013; single nucleotide polymorphisms). CA animals had their genotypes masked to simulate a medium-density panel (54,609 SNP). Fourteen imputation scenarios were evaluated, varying according to breed, sex, year of birth, and lineage. Imputation accuracy was determined based on the percentage of correctly imputed genotypes (PERC) and the squared Pearson&#x2019;s correlation between observed and imputed genotypes (R2). PERC values ranged from 66.52% to 97.39% and R&#xb2; from 0.6352 to 0.9780. The scenarios that included NE, CH, and CA (males or animals born before 2004) as the reference population for imputing CA females or CA animals born after 2004 showed the highest imputation accuracies. Therefore, the use of founder breeds in the reference population improves the accuracy of genotype imputation in CA cattle. The results indicate that a multibreed reference population, incorporating founder breeds, could provide a more robust and informative genetic basis for imputing composite cattle. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s13353-026-01060-z.

Animal breeding↗