Utilization of the sex-determining region Y gene in beef cattle breeding schemes

1991 ◽  
Vol 53 (2) ◽  
pp. 157-164 ◽  
Author(s):  
S. C. Bishop ◽  
J. A. Woolliams
Keyword(s):  
Beef Cattle ◽  
Male Offspring ◽  
Biological Efficiency ◽  
Normal Male ◽  
Sry Gene ◽  
Breeding Scheme ◽  
Genetic Progress ◽  
Cattle Breeding ◽  
Breeding Schemes ◽  
Normal Males

AbstractIn mammals ‘maleness’, i.e. the presence of testes, is thought to be controlled by a single gene on the Y chromosome. Recently, a candidate gene termed the SRY (sex-determining region Y) gene has been located. If the SRY gene is the gene causing maleness then a transgenic male with the SRY gene on an autosome would produce a greater proportion of male offspring than a normal male. This would be advantageous in situations where male offspring are more valuable than females. Such transgenic males have a reduced probability of propagating their genotype and an effort has to be made to avoid their extinction. This is at the cost of genetic progress which must be made to enable the transgenics to remain competitive with normal males.In a simulated beef cattle breeding scheme if half of the annual matings were made to transgenics then after 15 years of selection the transgenic males fell the equivalent of 2·6 years of selection behind males in a traditional herd. If all matings were made to transgenics they fell over 9 years behind. Selection for lean food conversion ratio was considered as an example. After 15 years of selection the gain in biological efficiency from more male offspring outweighed the loss from reduced genetic progress only when more than 0·5 of the bulls used in the breeding scheme were normal males. In practice, the difficulty of maintaining a small population of transgenic males along with other costs not included in the calculations suggest that breeding schemes in beef cattle with an SRY transgene would not be practicable without further technology.

A comparison of "bonus" and "quota" systems utilising the sry gene in beef cattle breeding

1993 ◽  
Vol 1993 ◽  
pp. 35-35
Author(s):  
S.C. Bishop ◽  
J.A. Woolliams
Keyword(s):  
Beef Cattle ◽  
Time Horizon ◽  
Mating Strategy ◽  
Mating Strategies ◽  
Sry Gene ◽  
Quota System ◽  
Cattle Breeding ◽  
Commercial Farms ◽  
Breeding Schemes ◽  
Traditional Breeding

The SRY gene controls the presence of testes (i.e. maleness) in mammals. This has been demonstrated by Koopman et al (1991), who bred transgenic XX mice with a copy of the SRY gene on an autosome which were phenotypically male, albeit infertile. A fertile XY male with a copy of the SRY gene on an autosome should, theoretically, produce a greater proportion of offspring which are phenotypically male. This would be advantageous in, for example, breeding Terminal beef sires, where male calves are more valuable than females calves on commercial farms. The possible use of beef cattle transgenic for the SRY gene was investigated by Bishop and Woolliams (1991) who found that there were small genetic advantages in breeding schemes using these bulls, compared to traditional breeding schemes, although there may be practical problems in running such schemes. Their findings pertained to a restricted mating strategy (the "quota" system) and a restricted time horizon (15 years), however. This paper investigates the possible application of the SRY gene considering different mating strategies and a flexible time horizon.

scholarly journals DNA Testing and Genetic Evaluation for Poll Breeding in Tropically Adapted Beef Cattle

Proceedings ◽  
2020 ◽  
Vol 36 (1) ◽  
pp. 98
Author(s):  
Imtiaz A.S. Randhawa ◽  
Michael R. McGowan ◽  
Laercio R. Porto-Neto ◽  
Ben J. Hayes ◽  
Russell E. Lyons
Keyword(s):  
Beef Cattle ◽  
Animal Welfare ◽  
Genetic Variants ◽  
Chromosome 1 ◽  
Health Production ◽  
Dna Testing ◽  
Genomic Evaluation ◽  
Cattle Breeding ◽  
Breeding Schemes ◽  
Estimated Breeding Values

In beef cattle, horn management is practiced to physically or surgically remove horns for the safety of animals and workers. However, invasive practices of dehorning and disbudding are a great threat to animal welfare, health, production and human safety, as well as labour intensive and costly. The most effective way to limit the impacts and costs of horns is to prevent their occurrences by breeding naturally polled (hornless) herds. Horn development is complex, although two mutually exclusive genetic variants (Celtic and Friesian) have been found prevalent on each copy of chromosome 1 in most polled cattle. Predicting genotypes in an animal is challenging. Available genetic testing assays were often limited in tropically adapted beef cattle. In this study we present a new optimized poll testing (OPT) assay, which has been bundled with SNP genotyping arrays being used for genomic evaluation in cattle. Breeding schemes can profile future parents for pure-polled stock based on the OPT results. We also evaluated the factors causing complexity in horn conditions. Thus, we coupled OPT predictions with head-status and sex distributions, by modelling genetic and non-genetic impacts, revealing that genetics, sex and sex hormones control horn ontology. Finally, concerns of polledness adversely affecting production and reproduction were investigated by using estimated breeding values of several beef traits. We found no detrimental effects of polledness on production or reproduction. Overall, this research concludes that genetically polled cattle will minimize issues about animal welfare and management costs without reducing production potentials in the tropically adapted beef cattle.

A maternal productive index for beef cows

1972 ◽  
Vol 12 (59) ◽  
pp. 573 ◽  
Author(s):  
RG Beilharz
Keyword(s):  
Beef Cattle ◽  
Reproductive Performance ◽  
Genetic Parameters ◽  
Selection Index ◽  
Beef Cows ◽  
Early Summer ◽  
Direct Measure ◽  
Important Goal ◽  
Genetic Progress ◽  
Cattle Breeding

To evaluate beef cows on their reproductive performance a maternal productive index (M.P.I.) was developed as an alternative to their evaluation in terms of simpler traits, or in terms of a conventional selection index based on simple traits. Data on M.P.I. were obtained from Hereford cows on three grazing treatments each containing three groups of cows differentiated by last breeding season (i.e. presence and age of calf at foot). The same cows were also scored for coat type on two occasions in late spring and early summer. The magnitude and change of coat score are explained by the hypothesis that nutritional stress delays the cycle of shedding of winter coat and its replacement by a sleek coat. Analysis of the correlations between coat score data and M.P.I. shows that low M.P.I. is also associated with a delay in change of coat type. This suggests that M.P.I. is an indication of adaptation of cows to their environment with poorly adapted animals suffering a greater stress. Because M.P.I. is a direct measure of a very important goal of beef cattle breeding it should be used widely in selection (or culling) of beef cows. Whether genetic progress will be faster than through the use of simpler traits, may be judged once genetic parameters have been estimated for M.P.I.

scholarly journals Beef cattle breeding in Australia with genomics: opportunities and needs

2012 ◽  
Vol 52 (3) ◽  
pp. 100 ◽  
Author(s):  
D. J. Johnston ◽  
B. Tier ◽  
H.-U. Graser
Keyword(s):  
Beef Cattle ◽  
Genomic Selection ◽  
Genetic Gain ◽  
Information Needs ◽  
Genomic Information ◽  
Female Reproduction ◽  
Genetic Progress ◽  
Cattle Breeding ◽  
Phenotypic Data ◽  
Genomic Predictions

Opportunities exist in beef cattle breeding to significantly increase the rates of genetic gain by increasing the accuracy of selection at earlier ages. Currently, selection of young beef bulls incorporates several economically important traits but estimated breeding values for these traits have a large range in accuracies. While there is potential to increase accuracy through increased levels of performance recording, several traits cannot be recorded on the young bull. Increasing the accuracy of these traits is where genomic selection can offer substantial improvements in current rates of genetic gain for beef. The immediate challenge for beef is to increase the genetic variation explained by the genomic predictions for those traits of high economic value that have low accuracies at the time of selection. Currently, the accuracies of genomic predictions are low in beef, compared with those in dairy cattle. This is likely to be due to the relatively low number of animals with genotypes and phenotypes that have been used in developing genomic prediction equations. Improving the accuracy of genomic predictions will require the collection of genotypes and phenotypes on many more animals, with even greater numbers needed for lowly heritable traits, such as female reproduction and other fitness traits. Further challenges exist in beef to have genomic predictions for the large number of important breeds and also for multi-breed populations. Results suggest that single-nucleotide polymorphism (SNP) chips that are denser than 50 000 SNPs in the current use will be required to achieve this goal. For genomic selection to contribute to genetic progress, the information needs to be correctly combined with traditional pedigree and performance data. Several methods have emerged for combining the two sources of data into current genetic evaluation systems; however, challenges exist for the beef industry to implement these effectively. Changes will also be needed to the structure of the breeding sector to allow optimal use of genomic information for the benefit of the industry. Genomic information will need to be cost effective and a major driver of this will be increasing the accuracy of the predictions, which requires the collection of much more phenotypic data than are currently available.

scholarly journals Genetic Progress in Multistage Dairy Cattle Breeding Schemes Using Genetic Markers

2005 ◽  
Vol 88 (4) ◽  
pp. 1569-1581 ◽  
Author(s):  
C. Schrooten ◽  
H. Bovenhuis ◽  
J.A.M. van Arendonk ◽  
P. Bijma
Keyword(s):  
Dairy Cattle ◽  
Genetic Markers ◽  
Genetic Progress ◽  
Cattle Breeding ◽  
Dairy Cattle Breeding ◽  
Breeding Schemes

Genetic progress in the lleyn group breeding scheme using a multitrait selection index

1995 ◽  
Vol 1995 ◽  
pp. 131-131
Author(s):  
G.E. Pollott ◽  
D.R. Guy ◽  
D. Croston
Keyword(s):  
Selection Index ◽  
Breeding Scheme ◽  
Genetic Progress ◽  
Group Breeding ◽  
North Wales ◽  
Group Members ◽  
Breeding Schemes ◽  
Set Up ◽  
Multitrait Selection ◽  
Made In

Group breeding schemes were introduced into Britain in the 1970s as a means of increasing the rate of genetic improvement in sheep and providing a vehicle for breeders to cooperate and pool resources. The Lleyn Group Breeding Scheme was set up in 1978 with the aim of improving several maternal traits in a breed known for its prolificacy. Although the breed originates from North Wales members of the group were drawn from different parts of Britain. Flocks in the scheme were all recorded by MLC and sheep had the possibility of being selected using MLC's selection index, appropriately weighted for the traits of interest to group members.This analysis was designed to investigate the genetic progress made in the scheme between 1979 and 1993. Three traits were analysed; adjusted early lamb weight (LW) (at eight weeks of age), mature weight (MW) (at 18-months) and litter size (LS) in the form Number of lambs born per ewe lambing (NLBEL). These three traits were investigated in ten flocks which participated in the scheme, at varying levels, during the 14-year period 1979-1993. However, only genetic progress in the nucleus flock is reported in this paper.

Genetic progress and inbreeding for alternative nucleus breeding schemes for beef cattle

1995 ◽  
Vol 61 (2) ◽  
pp. 231-239 ◽  
Author(s):  
B. Villanueva ◽  
G. Simm ◽  
J. A. Woolliams
Keyword(s):  
Beef Cattle ◽  
Mating Strategies ◽  
Percentage Increase ◽  
Expected Number ◽  
Genetic Progress ◽  
Multiple Ovulation ◽  
Population Sizes ◽  
Breeding Schemes ◽  
Nucleus Breeding ◽  
Selection Intensities

AbstractAlternative closed breeding schemes for beef cattle are analysed using stochastic computer simulation. Multiple ovulation and embryo transfer (MOET) schemes are compared with conventional schemes (schemes without MOET) with an equal expected number of progeny born per year. Schemes are compared for genetic gain and inbreeding obtained after 25 years of selection. The trait considered, evaluated in both sexes, has an initial heritability of 0·35. Different population sizes and numbers of sires selected are evaluated. Current realistic parameters for embryo production are assumed in MOET schemes.After 25 years of selection, and with no control on inbreeding, cumulative genetic gains are about 50% higher in MOET schemes compared with conventional schemes. The benefit from MOET is mostly due to increased selection intensities in females. The rate of inbreeding increases by up to nearly 300% when MOET is used. This maximum percentage increase in inbreeding following the use of MOET can be reduced to about 100% when selection and mating strategies for controlling inbreeding are used. The effect of the number of sires used on the inbreeding obtained is more important than the effect of the size of the herd. In MOET schemes, increasing the number of sires selected by a factor of three, leads to reductions in inbreeding rates of 40%. When schemes of the same size are compared at similar acceptable inbreeding levels, MOET schemes give around 30% higher genetic progress than conventional schemes.

Economic evaluation of beef cattle breeding schemes incorporating performance testing of young bulls for feed intake

2004 ◽  
Vol 44 (5) ◽  
pp. 393 ◽  
Author(s):  
J. A. Archer ◽  
S. A. Barwick ◽  
H.-U. Graser
Keyword(s):  
Beef Cattle ◽  
Feed Intake ◽  
Genetic Gain ◽  
Selection Criterion ◽  
Performance Testing ◽  
Cattle Breeding ◽  
Commercial Unit ◽  
Base Scenario ◽  
Breeding Schemes ◽  
The Impact

A model beef cattle breeding scheme consisting of a breeding unit and a commercial unit was used to evaluate the impact on genetic gain and profitability of incorporating feed intake measurements as an additional selection criterion in breeding programmes. Costs incurred by the breeding unit were compared with returns generated in the commercial unit, with bulls from the breeding unit being used as sires in the commercial unit. Two different market objectives were considered — a grass-fed product for the Australian domestic market, and a grain-fed product for the Japanese market. Breeding units utilising either artificial insemination or natural service were also considered. A base scenario was modelled incorporating a range of criteria available to Australian cattle breeders. A second scenario incorporated selection of sires for the breeding unit using a 2-stage selection process, with a proportion of bulls selected after weaning for measurement of (residual) feed intake. Measurement of feed intake of bulls improved accuracy of breeding unit sire selection by 14–50% over the equivalent base scenario, and genetic gain in the breeding objective was improved for all scenarios, with gains ranging from 8 to 38% over the base scenario. After accounting for the cost of measuring feed intake ($150–450), additional profit was generated from inclusion of feed intake measurement on a proportion of bulls for all breeding schemes considered. Profit was generally maximised where 10–20% of bulls were selected at weaning for measurement of intake, with improvement in profit ranging from 9 to 33% when optimal numbers of bulls were selected for intake measurement.

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