scholarly journals Selection for prolificacy in Finnsheep and in Norwegian sheep

1988 ◽  
Vol 60 (6) ◽  
pp. 518-522
Author(s):  
T. Ådnøy
Keyword(s):  
Litter Size ◽  
No Reduction ◽  
Selection Response ◽  
The Other ◽  
Group Differences ◽  
Carcass Quality ◽  
Production Traits ◽  
Breeding Scheme ◽  
Breed Group ◽  
Selection For

Litter size (LS) at birth and other production traits were recorded for Finnsheep (F), Norwegian(N) breeds Dala (D), Steigar (St) and Spael (Sp), for N sheep crossed with 1/4 F and ½ F and for a group of sheep established by collecting offspring of highly prolific N(N+) ewes. The N breeds and the ¼ F group were part of the national breeding scheme. In the 1/2F and N+, selection was solely for LSB. The other groups were selected normally. There were 4263 lambings. In adults, there were no breed group differences in lambing-% (mean 94 %), but in 1-yr. olds there were differences: Sp 90 %, F and F-crosses 80—85 %, D 70 %, N+ 60 % and St 50 %. F-crosses had clearly the best LS’s (Fca. 3.0, 1/2F2.4, 1/4F2.0). Those of N+ decreased through the 5 years recorded from near 2.0 to 1.8 lambs. The other breed groups gave LS’s of 1.7—1.8. In the two groups selected for LS, no selection response was found. The reasons are not known. Although the pure F and ½ F gave lower weaning weights (34 and 38 kg at 150d.) than the other groups (41—45 kg), their weaned lamb yield per ewe was ca. 20 kg higher. Considering the poorer carcass quality observed in earlier experiments for these groups, the use of 1/4 F is recommended for Norwegian conditions. This breed group gave no reduction in weaning weight, but increased the LS by some 0.2 lambs.

Selection and response within the nucleus of a sheep group-breeding scheme

1990 ◽  
Vol 51 (3) ◽  
pp. 593-599 ◽  
Author(s):  
S. Anderson ◽  
M. K. Curran
Keyword(s):  
Litter Size ◽  
Age Groups ◽  
Selection Response ◽  
Sheep Flock ◽  
Breeding Scheme ◽  
Average Value ◽  
Group Breeding ◽  
Selection For ◽  
Progeny Group ◽  
Selection Differentials

ABSTRACTAn evaluation of the response to selection for prolificacy within a nucleus sheep flock of a commercial group-breeding scheme is presented. In 1979, the Romney Group Breeders formed a nucleus flock of 120 prolific ewes chosen from 12 contributing flocks. A control flock was established in 1982 from the same source. The analysis was conducted on the trait of litter size. Selection differentials are presented for each year of birth progeny group in both flocks. Expected selection response was calculated from selection differentials and was found to have an average value of 1·5% of parent mean litter size per year. Using least squares procedures the litter size performance of control and nucleus ewes of 2, 3 and 4 years of age was corrected for environmental effects. Realized response was estimated from the differences between corrected litter size means of control and nucleus flocks. Response in litter size was found to be significant within years and within ewe age groups (P < 0·05).

scholarly journals The relevance of milk protein polymorphisms for dairy cattle breeding.

1993 ◽  
Vol 1993 ◽  
pp. 46-46
Author(s):  
Henk Bovenhuis
Keyword(s):  
Genetic Variants ◽  
Milk Protein ◽  
Production Traits ◽  
Milk Production Traits ◽  
Breeding Scheme ◽  
Cattle Breeding ◽  
Dairy Cattle Breeding ◽  
Nucleus Breeding ◽  
Selection For ◽  
Β Lactoglobulin

Several studies have shown milk protein genetic variants to be associated with manufacturing properties of milk. The main findings were that κ-casein genetic variants affect renneting time of milk and βlactoglobulin genetic variants are associated with casein number (reviewed by Grosclaude, 1988). There are reports also of associations between milk protein genetic variants and milk production traits. Results from these studies indicate that κ-casein genotypes are associated with protein content and βlactoglobulin genotypes are related to fat content (reviewed by Bovenhuis et al., 1992). Therefore, κ-casein and βlactoglobulin genotypes might be of value as selection criteria. The aim of the present study was to quantify the potential effects of selection for κ-casein and β-lactoglobulin genotypes by using stochastic simulation of a closed adult MOET nucleus breeding scheme.

Correlations between weaning weight, carcass traits and ultrasonic body measurements in Welsh Mountain sheep

1998 ◽  
Vol 1998 ◽  
pp. 84-84 ◽  
Author(s):  
M. Saatci ◽  
I. Ap Dewi ◽  
Z. Ulutas
Keyword(s):  
Litter Size ◽  
Carcass Traits ◽  
Carcass Quality ◽  
Body Measurements ◽  
Production Traits ◽  
Ultrasonic Scanning ◽  
Breeding Group ◽  
Genetic And Phenotypic Correlations ◽  
Mature Size ◽  
Lamb Growth

Selection in the CAMDA breeding group for Welsh Mountain sheep has been based since the start of the scheme on an index that includes litter size, maternal ability, lamb growth and mature size. Since 1987 fat and muscle depths have also been recorded in candidate replacement rams by ultrasonic scanning. Current consumer pressure to improve carcass quality suggests that emphasis be placed on developing an index that incorporates scanning results with other production traits. Construction of such an index requires estimates of the genetic and phenotypic correlations between traits in the selection objectives and criteria. Analyses were conducted to estimate these parameters based on data recorded in the nucleus of the CAMDA breeding group.

Correlations between weaning weight, carcass traits and ultrasonic body measurements in Welsh Mountain sheep

1998 ◽  
Vol 1998 ◽  
pp. 84-84
Author(s):  
M. Saatci ◽  
I. Ap Dewi ◽  
Z. Ulutas
Keyword(s):  
Litter Size ◽  
Carcass Traits ◽  
Carcass Quality ◽  
Body Measurements ◽  
Production Traits ◽  
Ultrasonic Scanning ◽  
Breeding Group ◽  
Genetic And Phenotypic Correlations ◽  
Mature Size ◽  
Lamb Growth

Selection in the CAMDA breeding group for Welsh Mountain sheep has been based since the start of the scheme on an index that includes litter size, maternal ability, lamb growth and mature size. Since 1987 fat and muscle depths have also been recorded in candidate replacement rams by ultrasonic scanning. Current consumer pressure to improve carcass quality suggests that emphasis be placed on developing an index that incorporates scanning results with other production traits. Construction of such an index requires estimates of the genetic and phenotypic correlations between traits in the selection objectives and criteria. Analyses were conducted to estimate these parameters based on data recorded in the nucleus of the CAMDA breeding group.

The effect of selection for litter size and litter weight at weaning in mice maintained on two diets

1963 ◽  
Vol 5 (3) ◽  
pp. 317-326 ◽  
Author(s):  
D. C. Dalton ◽  
T. L. Bywater
Keyword(s):  
Litter Size ◽  
Genetic Improvement ◽  
Random Mating ◽  
The Other ◽  
Response To Selection ◽  
Control Groups ◽  
Litter Weight ◽  
Dietary Switch ◽  
Selection For ◽  
Time Selection

SUMMARYAn experiment was carried out with mice over 24 generations to measure the response obtained to selection for litter size and litter weight at weaning on two dietary regimes designated normal and diluted. In addition, control groups bred by random mating were maintained on each diet. The stock were maintained on the diets from generation 0–3 after which time selection for the traits started and continued up to generation 17. After generation 17 for a further 6 generations, all selection stopped and half of each group was switched on to the other diet, while the remaining half continued as before.No significant response was obtained to selection for either litter size or litter weight at weaning.The diets provided did not bring about a differential response to selection for the traits, and the response to the dietary switch was small and temporary in its effect.Due to strong maternal effects and low heritability, little genetic improvement was obtained by selection for litter size and litter weight at weaning in these mice.

scholarly journals Breed group differences in the unsolvable problem task: herding dogs prefer their owner, while solitary hunting dogs seek stranger proximity

2021 ◽  
Author(s):  
Enya Van Poucke ◽  
Amanda Höglin ◽  
Per Jensen ◽  
Lina S. V. Roth
Keyword(s):  
Genetic Similarity ◽  
The Other ◽  
Group Differences ◽  
Test Apparatus ◽  
Human Relationship ◽  
Unsolvable Problem ◽  
Hunting Dogs ◽  
Breed Group ◽  
History Of ◽  
Breeding History

AbstractThe communicating skills of dogs are well documented and especially their contact-seeking behaviours towards humans. The aim of this study was to use the unsolvable problem paradigm to investigate differences between breed groups in their contact-seeking behaviours towards their owner and a stranger. Twenty-four dogs of ancient breeds, 58 herding dogs, and 17 solitary hunting dogs were included in the study, and their behaviour when presented with an unsolvable problem task (UPT) was recorded for 3 min. All breed groups interacted with the test apparatus the same amount of time, but the herding dogs showed a longer gaze duration towards their owner compared to the other groups and they also preferred to interact with their owner instead of a stranger. Interestingly, the solitary hunting dogs were more in stranger proximity than the other groups, and they also showed a preference to make contact with a stranger instead of their owner. Hence, we found differences in contact-seeking behaviours, reflecting the dog–human relationship, between breed groups that might not only be related to their genetic similarity to wolves, but also due to the specific breeding history of the dogs.

Estimation of Genetic Parameters and Selection Response for Reproductive and Growth Traits in Rideau-Arcott sheep

2020 ◽  
Author(s):  
Mohammed Naser Boareki ◽  
Luiz Brito ◽  
Angela Cánovas ◽  
V.R. Osborne ◽  
Flavio S Schenkel
Keyword(s):  
Litter Size ◽  
Genetic Parameters ◽  
Growth Traits ◽  
Reproductive Traits ◽  
Selection Response ◽  
Direct Selection ◽  
Correlated Response ◽  
Response To Selection ◽  
Weaning Weight ◽  
Selection For

The goal of this study was to estimate genetic parameters and predict direct and correlated response to selection for lamb growth traits and ewe reproductive traits, based on single trait selection or combining multiple traits in an optimum index that targets total litter post-weaning weight in the first lambing as the main selection goal. Heritability estimates ranged from 0.04 to 0.19. Genetic correlations between growth and reproductive traits ranged from -0.24 to 0.15. The indirect response to selection for reproductive traits in later lambings, by selecting on first lambing performance, was 11 to 25% greater than direct selection. The response to indirect selection for composite reproductive traits, i.e. total weaning weight or total post-weaning weight, by selecting on individual lamb weaning weight or post-weaning weight was 1 to 69% greater than direct selection, but it was accompanied by a negative response on litter size. However, combining alternate growth and reproductive traits in optimum selection index resulted in correlated response of up to 96% greater than direct selection response for reproductive traits without a negative response on litter size. Therefore, multiple trait selection using an index of component traits was more effective than direct selection for a composite trait.

Genetic implications of a simulation model of litter size in swine based on ovulation rate, potential embryonic viability and uterine capacity: II. Simulated selection.

1990 ◽  
Vol 68 (4) ◽  
pp. 980-986 ◽  
Author(s):  
G. L. Bennett ◽  
K. A. Leymaster
Keyword(s):  
Simulation Model ◽  
Litter Size ◽  
Selection Pressure ◽  
Selection Response ◽  
Ovulation Rate ◽  
Direct Selection ◽  
Weak Selection ◽  
Embryo Survival ◽  
Swine Population ◽  
Selection For

Abstract Direct selection for ovulation rate, uterine capacity, litter size and embryo survival and selection for indexes of ovulation rate with each of the remaining traits were simulated for a swine population. The relationships among these traits were determined from a simulation model that assumed that litter size was always less than or equal to both ovulation rate and uterine capacity. Heritabilities of ovulation rate and uterine capacity were assumed to be .25 and .20, respectively, and uncorrelated genetically and phenotypically. No additional genetic variation was assumed. Responses to weak selection pressure were simulated by recurrent updating of phenotypic variances and covariances combined with the heritabilities of ovulation rate and uterine capacity. Two indexes of ovulation rate and uterine capacity each resulted in 37% greater increase in litter size than direct selection for litter size. Indexes of ovulation rate and either litter size or embryo survival increased litter size by 21% more than direct selection for litter size. Selection for ovulation rate, uterine capacity or embryo survival was 6, 35 and 79%, respectively, less effective than direct selection for litter size. Responses to intense selection pressure were determined by direct simulation of genotypes and phenotypes of individuals. The two indexes of ovulation rate and uterine capacity exceeded direct selection for litter size by 39 and 27%. The indexes of ovulation rate and either litter size or embryo survival exceeded direct selection for litter size by 19 and 13%, respectively. Intense selection for ovulation rate or uterine capacity decreased selection response by 26 and 67%, respectively, relative to direct selection for litter size. Intense selection for embryo survival decreased litter size slightly.

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