Evaluation of the efficiency of alternative selection schemes and breeding objectives in dairy sheep of Greece

1997 ◽  
Vol 64 (3) ◽  
pp. 453-461 ◽  
Author(s):  
A. Kominakis ◽  
G. Nitter ◽  
D. Fewson ◽  
E. Rogdakis
Keyword(s):  
Genetic Gain ◽  
Breeding Value ◽  
Dairy Sheep ◽  
Model Calculations ◽  
Selection Scheme ◽  
Selection Responses ◽  
Breeding Objective ◽  
Breeding Objectives ◽  
Fat Yield ◽  
Of Greece

AbstractThe genetic and economic efficiency of alternative selection schemes and breeding objectives for the Karagouniki dairy sheep in Greece was investigated by model calculations. Criteria of efficiency were the annual genetic gain for the aggregate breeding value, the profit per ewe in the population and the annual selection responses for single traits. The introduction of a two-tier selection scheme, where the recorded ewes are separated into a nucleus and a pre-nucleus, was found superior in both genetic and economic terms for a breeding objective comprising the traits milk yield and number of lambs weaned per ewe per annum. Highest rates for annual genetic gain and selection responses were obtained when the nucleus size was proportionately 0·05 of the population (200 000 ewes), the size of the test matings 0·50 to 0·60 of the size of the pre-nucleus unit (0·10 of the population) and the number of daughters per test ram 40. Opening the nucleus to replacement ewes from the lower tier did not affect positively the annual genetic gain and the selection responses. Furthermore, a breeding objective comprising the traits fat yield and number of lambs weaned per ewe and per annum was found very efficient in both genetic and economic terms while selection on growth and carcass traits did not seem to be justified.

scholarly journals Breeding objectives for three silvicultural regimes of radiata pine

2001 ◽  
Vol 31 (4) ◽  
pp. 654-662 ◽  
Author(s):  
Luis A Apiolaza ◽  
Dorian J Garrick
Keyword(s):  
Genetic Gain ◽  
Genetic Correlations ◽  
Pulp Mill ◽  
Radiata Pine ◽  
Breeding Strategy ◽  
Breeding Objective ◽  
Breeding Objectives ◽  
The Difference ◽  
Average Wood

A generic vertically integrated firm, comprising a production forest, a sawmill, and a pulp mill was modelled under three silvicultural regimes: direct to pulp, intermediate (includes production thinning), and intensive (includes production thinnings and pruning). The harvest age traits included in the breeding objective were total volume (m3/ha) and average wood density (kg/m3). Economic values for each trait were calculated as the difference in discounted profit for a unit marginal increase of volume or density, and expressed as relative weights to facilitate comparisons between the objectives. The methodology was applied to a Chilean case study using representative economic and production circumstances. The breeding objectives so derived were 1vol + 2.4den for pulp, 1vol + 1.1den for intermediate, and 1vol + 1.2den for the intensive regime, where vol and den are the breeding values for volume and density, respectively. The firm was profitable under all regimes. Genetic correlations between the objectives for each regime were higher than 0.9, indicating that a single breeding strategy with objective 1vol + 1.5den could be adopted, with almost no loss of genetic gain relative to selecting for a particular silvicultural regime.

Sensitivity of response of multi-trait index selection to changes in genetic correlations between production traits in sheep

2006 ◽  
Vol 46 (3) ◽  
pp. 283 ◽  
Author(s):  
E. Safari ◽  
N. M. Fogarty ◽  
A. R. Gilmour
Keyword(s):  
Genetic Correlations ◽  
Fibre Diameter ◽  
Wishart Distribution ◽  
Index Selection ◽  
Production Traits ◽  
Environmental Variance ◽  
Selection Responses ◽  
Breeding Objective ◽  
Breeding Objectives ◽  
Sheep Production

Complex sheep breeding objectives and the inclusion of more traits in genetic evaluation requires more accurate genetic parameters. There are few estimates of genetic correlations, especially between the major sheep production trait groups and they are generally variable with large standard errors. This study examines the sensitivity of response to multi-trait index selection for a range of genetic correlations between major traits (growth, wool, carcass, reproduction and worm resistance) under 3 breeding objectives (fine wool, dual-purpose wool/meat and meat) relevant to Australian sheep enterprises. Factor analysis identified the major factors explaining the underlying variability in the matrix of base genetic correlations for each breeding objective. Monte Carlo simulation studied the effect of changes in the genetic correlations under 3 index scenarios with the genetic and environmental variance–covariance matrices sampled independently from a Wishart distribution. The sensitivity of responses to selection over the range of correlations varied with the breeding objective. Selection responses were sensitive under all objectives for the range of correlations for reproduction with wool traits and in at least some objectives for reproduction with growth, worm resistance and carcass muscling. Selection responses in the fine wool objective were highly sensitive to the correlation between growth and fibre diameter. The results provide a logical basis for setting priorities for studies to obtain more accurate estimates of genetic correlations among sheep production traits.

A simulation study of open nucleus and closed nucleus breeding systems in a sheep population

1995 ◽  
Vol 60 (1) ◽  
pp. 117-124 ◽  
Author(s):  
J. A. Roden
Keyword(s):  
Genetic Gain ◽  
Live Weight ◽  
Breeding Systems ◽  
Breeding Value ◽  
Linear Unbiased Prediction ◽  
Sheep Population ◽  
Best Linear Unbiased ◽  
Nucleus Breeding ◽  
Open Nucleus ◽  
Selection Of

AbstractStochastic simulation was used to compare the results of alternative breeding systems in a sheep population divided into 10 flocks of 120 ewes. The breeding systems compared were selection within closed flocks (CF), a closed nucleus system (CNS), an open nucleus system (ONS) and open nucleus systems with the selection of nucleus replacements being restricted to either nucleus born males (ONSRm) or nucleus born females (ONSRf). Selection was for a best linear unbiased prediction of breeding value for lamb live weight which had a heritability of 0·17. The open nucleus breeding systems (ONS, ONSRm, ONSRf) resulted in higher rates of genetic gain, more predictable selection responses and lower rates of inbreeding than either the closed nucleus system (CNS) or selection within closed flocks (CF). Initial genetic differences between flocks resulted in higher rates of genetic gain in the nucleus breeding systems due to the use of between flock genetic variance. In the ONS system up to 25% of nucleus sires and approximately 50% of nucleus dams were born in base flocks. Nevertheless if selection of either nucleus sires or dams was restricted to nucleus born animals there was very little change in genetic gain or rate of inbreeding.

scholarly journals Prediction of genetic gains for breeding objective traits and designing selection schemes for Washera and Gumuz indigenous sheep

2021 ◽  
Vol 4 (1) ◽  
pp. 1-13
Author(s):  
Sisay Asmare ◽  
Sisay Asmare ◽  
Kefyalew Alemayehu ◽  
Solomon Abegaz K. ◽  
Aynalem Haile ◽  
...  
Keyword(s):  
Litter Size ◽  
Selection Index ◽  
Genetic Response ◽  
Breeding Scheme ◽  
Selection Scheme ◽  
Genetic Gains ◽  
Washera Sheep ◽  
Indigenous Sheep ◽  
Breeding Objective ◽  
One Year

In Ethiopia,there are 32.85 millions of sheep,more than 99 % of which are indigenous.However,the productivity of local sheep under traditional production system is low with high mortality of sheep.There are two ways of improving performance of sheep and goats,namely improving the enviroment of animals and/or improving there genetic potential.The aim of this study was to predict genetic gains of breedingobjective traits and select the best sheep selection scheme for Gumuz andWashera sheep. Body size(six month weight and yearling weight) and litter size were breeding objective traits identified by own flock animal ranking experiment and personal interview. Deterministic approach of ZPLAN computor program is used for modeling input parametres of Gumuz and Washera sheep and simulating breeding plans using gene flow method and selection index procedures. One-tier cooperative sheep breeding scheme were proposed whereby ram exchange between and within villages is the main means of genetic dissimination. Genetic gains predicted for six month weight of Gumuz and Washera sheep were 0.43 and 0.55 kg,respectively. Genetic gains predicted for yearling weight of Gumuz and Washera sheep were 0.55 and 0.60 kg,respectively. Genetic gains predicted for litter  size of Gumuz and Washera sheep were 0.08 and 0.09 lambs,respectively. The lower rate of inbreeding, the higher monetary genetic gain for aggregate genotype,higher return to investmnet and higher profit/ewe/year were quality measures of breeding program considered to prefer scheme 4 for both Gumuz and Washera sheep.Hence,for both Gumuz and Washera sheep populations a sheep selection scheme designed with 15 % selection proportion and one year ram use for breeding was recommended. Special emphasis need to be given to yearling weight with higher predicted genetic response and higher percentage return to investment.

Genetic parameters and responses to selection for pre-weaning growth in suffolk and texel sheep

1995 ◽  
Vol 1995 ◽  
pp. 48-48
Author(s):  
I.W. Purvis ◽  
J.P. Hanrahan
Keyword(s):  
Growth Rate ◽  
Genetic Variation ◽  
Genetic Gain ◽  
Genetic Parameters ◽  
Growth Traits ◽  
Present Report ◽  
Growth Data ◽  
Genetic Trend ◽  
Breeding Objective ◽  
Selection For

In order to evaluate genetic gain in populations under selection it is necessary to be able to partition the observed response into genetic and environmental components. This requires estimates of the appropriate genetic and environmental (co)variances unless appropriate genetic controls are available. Growth rate is an important component of the breeding objective for sheep breeds used as terminal sires and, whereas older estimates of the contribution of genetic variation to differences in preweaning growth indicated heritabilities of the order of 0.1, more recent studies have indicated considerably higher values. The present report concerns analyses of preweaning growth data on purebred Suffolk and Texel sheep to estimate genetic parameters for preweaning growth traits and genetic trend in growth rate from birth to weaning.

scholarly journals Selection responses for egg production of Fayoumi and Rhode Island Red breeds

2016 ◽  
Vol 19 (1-2) ◽  
pp. 66-73
Author(s):  
ME Haque ◽  
GK Deb ◽  
MN Hasan ◽  
MH Ali
Keyword(s):  
Rhode Island ◽  
Genetic Gain ◽  
Egg Production ◽  
Management Practices ◽  
Selection Responses ◽  
Lower Productivity ◽  
Significant Difference ◽  
F2 Generation ◽  
Foundation Stock ◽  
F1 Generation

This experiment estimated the selection responses for egg production of Fayoumi (Fay) and Rhode Island Red (RIR) breeds. A total of 3000; belonging Fay 2000 & RIR 1000 day old chicks were collected from Egypt and Bangladesh Livestock Research Institute (BLRI), Savar, Dhaka respectively, considered as foundation stock. The chicks were brooded for 5 weeks and reared up to 14 weeks of age providing standard feeding and management. After brooding, 640 Fay and 504 RIR pullets were reared in 40 and 36 individual pens respectively, considering as a family. Finally, 30 and 24 best families of Fay and RIR respectively were selected with 420 Fay and 288 RIR pullets at 15 weeks of age, on the basis of age at 1st egg lay, egg production and fertility. Salmonella and mycoplasma free eggs were collected on the basis of blood test (agglutinate test) from the selected families of both the breeds and hatched out for next generation. The experiment was continued up to 40 weeks of age for each generation. The study revealed that hen day egg production of Fay and RIR was higher in Foundation stock (64.39% in Fay and 68.54% in RIR) than that of F1 generation (58.6% in Fay and 46.8% in RIR) but no significant difference (P > 0.05) was observed for livability between Foundation stock and F1 generation. Reasons for lower productivity in F1 generation may be the poor management practices during growing period. In F2 generation, egg production was higher in both the breeds (64.09% in Fay and 62.05% in RIR) than in F1 generation. Egg production of RIR was not recorded for F3 generation, as their ability to adopt under farmers condition was very poor. However, in F3 generation, egg production of Fay was higher (65.82%) than in F2 generation. Genetic gain in Fay was 0.06%, 0.11% and 0.12% for F1, F2 and F3 generation, respectively. In case of RIR genetic gain was 0.07% in F1 and 0.18% in F2 generation. Due to selection slight genetic gain for egg production was obtained in Fay and RIR but further research with larger stock is needed for better understanding of selection responses of these breeds.Bangladesh J. of Livestock Res. 19(1-2): 66-73, Jan-Dec 2012

The relative importance of energy and protein in the concentrate on intake and yield of milk constituents by freisland ewes offered hay ad-libitum

1994 ◽  
Vol 1994 ◽  
pp. 207-207
Author(s):  
R.G. Wilkinson ◽  
C.M. Minter ◽  
G. Duffy ◽  
J. Celerier
Keyword(s):  
Dairy Cows ◽  
Crude Protein ◽  
Relative Importance ◽  
Dairy Sheep ◽  
Total Response ◽  
Metabolisable Energy ◽  
Forage Intake ◽  
Fat Yield ◽  
Protein Supply ◽  
To Receive

Increasing the level of concentrate fed to lactating ruminants reduces forage intake, but increases the yield of milk and milk constituents (Aston et al. 1991). However, the proportion of the total response due to additional metabolisable energy (ME) or crude protein supply (CP) is unclear. Recent work with dairy cows (Aston et al. 1992) suggests that additional ME or CP fed as concentrate reduced and slightly increased silage intake respectively. Additional CP had twice the effect on milk and three times the effect on protein yield than additional ME. However, ME and CP were equally important in determining fat yield. The objective of the trial was to investigate whether dairy sheep respond to additional ME or CP supply as concentrate in a similar way to dairy cows.Three concentrate diets were formulated to contain 13.0 MJ/kg DM ME and either 100 (A), 200 (B) or 400 (C) g/kg DM CP. After weaning (6 weeks), 24 mature Freisland ewes were housed individually, and allocated by liveweight and initial milk yield to receive concentrate DM at daily rates of 0.8 kg, providing 10.4 MJ/day ME and 160 (B) or 320 (C) g/day CP (LLP, LHP), or 1.6 kg, providing 20.8 MJ/day ME and 160 (A) or 320 (B) g/day CP (HLP, HHP). The trial lasted 8 weeks and was analysed as a 2 X 2 factorial design.

scholarly journals Comparison of long-term selection responses of breeding policy in dairy herds

2011 ◽  
Vol 50 (No. 10) ◽  
pp. 439-449
Author(s):  
P. Šafus ◽  
J. Přibyl
Keyword(s):  
Embryo Transfer ◽  
Genetic Gain ◽  
Negative Selection ◽  
Milk Proteins ◽  
Breeding Value ◽  
Dairy Herds ◽  
Selection Intensity ◽  
Term Selection ◽  
Single Use ◽  
Selection Of

Genetic and economic responses to genetic gain were evaluated for these breeding arrangements: single use of bulls under testing; single and repeated use of proved bulls for two years and for three years (in combination with selection intensity 1%, 5% or 10% of the best bulls for the use of proved bulls); negative selection of cows in the herd &ndash; 10%, 20% or 30% of animals are discarded from reproduction and the animals are left in the herd and used for breeding by beef bulls; negative selection of first-calvers in the herd &ndash; 10%, 20% or 25% of animals are discarded for slaughter; discarding of heifers and purchase of animals with higher breeding value, and embryo transfer &ndash; a group of selected recipients accounts for 10%, 20% or 30% of the cows with lover breeding value in the dairy herds. Simulations for single use of breeding arrangements and their consequences over a fifty-year period were carried out for the above models using the gene flow method. Only minimum changes will occur since the 25<sup>th</sup> year of observation. A comparison of the particular models showed the highest gain of proved bulls selected from 1% of the best bulls whose cumulative genetic gain was 41.558 kg of milk proteins on average per cow for the whole observed period. Single use of bulls under testing in the herd resulted in the second highest cumulative genetic gain. Use of proved bulls selected with lower selection intensity (5% or 10%) had worse results. Culling of cows and discarding of first-calvers for slaughter led to lower genetic and economic contribution. The gain of embryo transfer was also lower; moreover, it is not economically advantageous for its very high costs, so it should not be used in production herds generally. High genetic and economic gain was recorded for replacement of all heifers by animals with higher breeding value from other populations. &nbsp;

Efficiency of nucleus breeding schemes in dual-purpose cattle of Tanzania

1990 ◽  
Vol 50 (2) ◽  
pp. 245-251 ◽  
Author(s):  
J. S. Kasonta ◽  
G. Nitter
Keyword(s):  
Artificial Insemination ◽  
Genetic Gain ◽  
Cattle Breed ◽  
Progeny Testing ◽  
Environment Interaction ◽  
Dual Purpose ◽  
Model Calculations ◽  
Dual Purpose Cattle ◽  
Total Profit ◽  
Breeding Schemes

ABSTRACTFor the Mpwapwa cattle breed in Tanzania, the efficiency of various breeding schemes including an open nucleus was investigated by model calculations. Artificial insemination and intensive recording of production are assumed to be applied in a nucleus which is the main breeding unit. As a pre-nucleus, associated herds with less intense data recording serve as the basis to screen superior cows for nucleus replacements, provide the capacity for progeny testing, and operate as bull multipliers for commercial herds.The criteria of efficiency were genetic gain and profit from selection for a dual purpose breeding objective (milk and beef) in a total population of 10 000 cows. Introducing a two breeding tier scheme through separating all recorded cows into a nucleus and pre-nucleus leads to an increase of the genetic gain rather than the profit. Further improvement is obtained by introduction of artificial insemination in pre-nucleus herds. The nucleus size should not exceed about 5% of the cow population and an optimum size of the pre-nucleus is about 15%. Opening the nucleus to replacement cows coming from the pre-nucleus affects the aggregate genetic gain very little although it can be recommended if milk yield is to be mainly improved or if the total profit is taken into account. Furthermore, the nucleus should be opened if there is little difference between the heritabilities in the nucleus and pre-nucleus and also in order to avoid detrimental effects of inbreeding and genotype × environment interaction.

Sire evaluation using animal model versus differentconventional methods in red sindhi cattle

2016 ◽  
Author(s):  
P. K. Mallick ◽  
A. K. Ghosh ◽  
A. S. Rajendiran
Keyword(s):  
Animal Model ◽  
Genetic Gain ◽  
Simplex Method ◽  
Animal Husbandry ◽  
Breeding Value ◽  
Sire Evaluation ◽  
Improvement Programme ◽  
Breed Improvement ◽  
Model Versus ◽  
Selection Of

The effectiveness of sire evaluation is the backbone of any breed improvement programme as much as 61% of genetic gain in dairy cattle results from selection of sires through “bulls to breed cows” and “bulls to breed bulls” path. The application of latest and simplex method of sire evaluation like BLUPF90 in Indian breeds is scanty. The present investigation was planned to evaluate the Red Sindhi sires by this method and to compare the effectiveness of BLUPF90 method with other conventional methods of sire evaluation in Red Sindhi cattle. The records of production and reproduction performances of first lactation traits of 717 Red Sindhi cows, progeny of 58 sires, spread over a period of 40 years (1966-2005) from CCBF, Chiplima, Orissa under the control of Department of Animal Husbandry, Dairying and Fisheries, Ministry of Agriculture, Government of India and CBF, Kalsi, Deheradun, Uttarakhand were analyzed. The present study was single and multi-trait evaluation of breeding values of Red Sindhi sires. The overall least squares population mean for first lactation milk yield (FLMY) was 1536.35±54.87 kg. The average breeding value of sires of single trait from different methods ranged from 1536.35 kg (LSM, DFREML and BLUPF90-Dairy Pack) to 1588.50 kg (simple daughter average) but in multi-trait method the breeding value does not vary with each other. The comparison of different method of sire evaluation based on single trait for FLMY only shows that the DFREML model for single trait should be preferred over the BLUP, LSM and simple daughter average methods for evaluating the sire breeding value. However, if a sire-breeding value is to be computed from multi traits then BLUPF90 model may be preferred over DFREML model.

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