scholarly journals GENETIC TRENDS IN PERFORMANCE OF THE ROMNELET SHEEP DURING THE PERIOD OF BREED DEVELOPMENT

1961 ◽  
Vol 41 (1) ◽  
pp. 126-133 ◽  
Author(s):  
H. F. Peters ◽  
S. B. Slen ◽  
H. J. Hargrave
Keyword(s):  
Birth Weight ◽  
Early Years ◽  
Weaning Weight ◽  
Significant Change ◽  
Fleece Weight ◽  
F2 Generation ◽  
Genetic Trends

Performance records on the Romnelet sheep, developed from the Romney X Rambouillet cross [with introductions of Targhee and Romeldale in the early years], were analysed to determine genetic trends in birth weight, weaning weight, 18-month weight of ewes and yearling clean fleece weight from the F1 to the F7 generation.There were statistically significant (P < 0.01) reductions of 1.3 pounds in birth weight, 7.5 pounds in weaning weight at an average age of 136 days, 7.0 pounds in 18-month weight of ewes and 0.6 pound in yearling clean fleece weight from the first-cross to the F2 generation. There was a further significant (P < 0.05) decline of 0.6 pound in birth weight and a significant (P < 0.01) decline of 0.5 pound in clean fleece weight after the F2 generation, but no further significant change occurred in 18-month weight of ewes. There was a significant (P < 0.05) increase of 7.8 pounds in weaning weight in the later generations.

scholarly journals AN APPRAISAL OF SELECTION IN THE ROMNELET SHEEP

1961 ◽  
Vol 41 (2) ◽  
pp. 205-211
Author(s):  
H. F. Peters ◽  
S. B. Slen ◽  
H. J. Hargrave
Keyword(s):  
Birth Weight ◽  
Selection Pressure ◽  
Upward Trend ◽  
Weaning Weight ◽  
Selection For ◽  
Fleece Weight ◽  
One Year ◽  
Selection Differentials ◽  
Made In ◽  
Genetic Trends

The amounts of selection for birth weight, weaning weight, post-weaning gain up to about 1 year of age and yearling clean fleece weight in the development of the Romnelet breed of sheep are reported.The selection differentials for weaning weight only were statistically significant (P < 0.05) for both sexes. Analyses of regression of mean differential on time showed an upward trend in the differentials for birth weight and weaning weight, but there was no evidence of significant yearly trend in the differentials for post-weaning traits. Trends in selection pressure were consistent with the reported genetic trends in performance after the initial decline in performance from F1 to F2.Weaning weight received more attention in selection than any other trait studied, and the most genetic improvement was made in this trait. The large reduction in numbers of animals available for selection from birth to one year of age, due mainly to heavy culling of lambs at weaning, brought about a reduction in selection intensity from 22 per cent to 10 per cent for post-weaning gain and from 42.5 to 22 per cent for clean fleece weight.

The role of selection in the improvement of Welsh Mountain sheep

1958 ◽  
Vol 9 (6) ◽  
pp. 819 ◽  
Author(s):  
JM Doney
Keyword(s):  
Birth Weight ◽  
Maternal Environment ◽  
Weaning Weight ◽  
Phenotypic Correlations ◽  
Selection For ◽  
Heritability Estimates ◽  
Fleece Weight ◽  
Staple Length

Means and variances of several economic characters in Welsh Mountain sheep are given. The repeatabilities of, and phenotypic correlations between, these characters are generally within the range of similar estimates given for other breeds. Heritabilities, calculated from parent-offspring correlations, were : birth weight 0.39, weaning weight 0.68, 18-month weight 0.59, greasy fleece weight 0.61, and staple length 0.73. These values are in general higher than similarly derived estimates from other breeds. A method of correcting heritability estimates to remove the error due to correlation between maternal environment, and the character as measured in the dam, is described. This reduces the estimate for weaning weight to 0.48, and that for 18-month weight to 0.16, but does not change that for fleece weight. The use of such estimates in predicting the effect of selection is discussed, and it is concluded that accurate selection for the chosen economic characters will result in improvement at the present genetic stage of the breed.

Heterosis in crossbred hill sheep

1963 ◽  
Vol 5 (3) ◽  
pp. 289-299 ◽  
Author(s):  
H. P. Donald ◽  
J. L. Read ◽  
W. S. Russell
Keyword(s):  
Birth Weight ◽  
The Other ◽  
Weaning Weight ◽  
Bone Length ◽  
The Mean ◽  
Fleece Weight ◽  
Reproductive Characters

SUMMARY1. For ten years purebred Blackface and Swaledale ewes have been kept on a small hill grazing together with first crosses and backcrosses to the Swaledale. The total flock of about 120 ewes was mated and lambed on sown pastures where ewes with twins remained from lambing until weaning. Four new rams (two of each breed) were used each year.2. It is concluded that the Swaledales produced fewer lambs than the other ewes, but these were of greater birth weight (5 %) and cannon bone length (2 %); moreoever, they were better mothers than Blackface (4 %) when rearing singles on hill grazing but not if rearing twins on sown grass.3. Blackface sheep showed greater weights at weaning (5%), at mating (5%), and of fleece (15%) than did pure Swaledales.4. First cross sheep were equal to or slightly superior to the parental mean in birth weight, weaning weight and cannon-bone length. They exceeded the better parent in ewe weight, first fleece weight, and weight of weaned lambs.5. Backcross sheep although not always statistically distinguishable from Swaledale in cannon-bone length and fleece weight or from first cross sheep in reproductive characters tend to confirm the interpretations placed on the relations between the purebred and first cross sheep.6. Heterosis estimated as a superiority of first cross sheep over the mean of the two parental breeds varied from 0% for cannon-bone length to 9·5% for prolificacy of 4-year-old ewes.

35 Detecting Effective Starting Point of Genomic Selection by Divergent Trends from BLUP and ssGBLUP

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 19-19
Author(s):  
Rostam Abdollahi-Arpanahi ◽  
Daniela Lourenco ◽  
Ignacy Misztal
Keyword(s):  
Birth Weight ◽  
Beef Cattle ◽  
Genomic Selection ◽  
Single Step ◽  
Weaning Weight ◽  
Start Date ◽  
Angus Cattle ◽  
Starting Point ◽  
Essential Question ◽  
Genetic Trends

Abstract Genomic selection has been adopted nationally and internationally in different livestock and plant species. However, understanding whether genomic selection has been effective or not is an essential question for both industry and academia. Once genomic evaluation started being used, estimation of breeding values with pedigree BLUP became biased because this method does not consider selection using genomic information. Hence, the point of divergence of genetic trends obtained with BLUP and Single-step genomic BLUP (ssGBLUP) may indicate the start date of genomic selection. This study aimed to find the start date of genomic selection for a set of economically important traits in pigs and Angus cattle by comparing genetic and Realized Mendelian sampling (RMS) trends obtained using BLUP and ssGBLUP. In pigs, the genetic trends from ssGBLUP and BLUP diverged for all traits with different intensity. In beef cattle, the trends started diverging in 2009 for weaning weight and in 2016 for postweaning gain, with little divergence for birth weight. In pigs, the RMS trends from ssGBLUP and BLUP diverged strongly for one trait and weakly for another trait. In beef cattle, the RMS trends started diverging in 2009 for weaning weight and in 2016 for postweaning gain, with little trend for birth weight. Divergence of the genetic trends from ssGBLUP and BLUP indicate onset of the genomic selection. Presence of trends for RMS indicates selective genotyping, with or without the genomic selection. The onset of genomic selection and genotyping strategies agree with industry practices across the two species. In summary, the effective start of genomic selection can be detected by the divergence between genetic and RMS trends from BLUP and ssGBLUP.

Characters of economic importance in Welsh Mountain sheep

1962 ◽  
Vol 4 (2) ◽  
pp. 269-278 ◽  
Author(s):  
D. C. Dalton
Keyword(s):  
Body Weight ◽  
Genetic Variation ◽  
Birth Weight ◽  
Milk Production ◽  
Milk Yield ◽  
Early Growth ◽  
Economic Importance ◽  
Weaning Weight ◽  
Good Guide ◽  
Fleece Weight

1. The influence of seasonal, maternal and genetic variation on body weight and fleece characters of Welsh Mountain sheep is reported.2. Fertility and rearing ability of ewes improved from first to third lamb crop.3. Male lambs were on average 0·4 lb. heavier at birth than females. Birth weight increased with number of pregnancies of the dam.4. Early growth of the lamb between birth and marking (24 days old) used partly as a measure of milk production of the ewe, was greater in males than in females. Lambs born to older ewes made the greatest gains over this period, although the trend was not significant.5. Weaning weight of the lamb was affected by the dam's weight at tupping, the number of preceeding pregnancies, her milk yield and also by the season in which the lamb was born. Despite these effects weaning weight proved a good guide to the weight (at subsequent matings) at 1½ and 2½ years old.Heritability by intra-sire parent-offspring regression was 0·51±0·07 (P<0·001) and repeatability was 0·43 (P<0·001).6. Fleece weight was not affected by season or age of ewe. However, the heaviest lambs at weaning tended to have heaviest fleeces the following year.Heritability by intra-sire daughter-dam comparison was 0·58±0·11 (P<0·001) and repeatability was 0·46 (P<0·001).7. Staple length measured on the mid-side of the animal had a repeatability between years of 0·56 (P<0·001) while heritability by daughter-dam regression was 0·38±0·ll (P<0·001).8. Fourteen Welsh Mountain rams were progeny tested. Nine of the rams were purchased at local sales and 5 were home bred. They were not selected for the traits examined.No statistically significant differences were obtained between sire progeny groups for weaning weight and fleece weight.

scholarly journals Least Square Analysis of Variance for the Assessment of Natural Consequences for Birth Weight, Weaning Weight, Yearling Weight, Pre-weaning Daily Weight Acquire, and Greasy Fleece Weight of Kajli Sheep in Pakistan

2021 ◽  
pp. 1-8
Author(s):  
Farm anullah ◽  
◽  
Momen Khan ◽  
Keyword(s):  
Birth Weight ◽  
Mixed Model ◽  
Average Daily Gain ◽  
Least Square ◽  
Essential Difference ◽  
Birth Season ◽  
Weaning Weight ◽  
Fleece Weight ◽  
Generation Information ◽  
Male Sheep

The current study was completed to analyze the effect of natural components on various improvement affecting traits of Kajli sheep in Pakistan. For this reason, we apply two huge contemporary datasets in sheep to explore factors that influence the traits. Therefore, the generation information record of 13715 Kajli sheep lambing accumulated from 1994 to 2010 at Livestock Experimental Stations Khushab and Khizarabad, Punjab. Information records were genuinely analyzed through utilizing PC modified Mixed Model Harvey’s Least Squares and Maximum Likelihood. The two farms information data was analyzed by utilizing an animal model program. The factual model was incorporated to evaluate the Birth Weight (BW), 120 days at Weaning Weight (WW), Pre-Weaning Average Daily Gain (PRADG), Yearling Weight (YW) and Greasy Fleece Weight (GFW). Year of Birth (YOB), Birth Season (BS), Birth Types (BT) and sex was the fix effect in the model. Results indicated that, the overall general values for birth weight, weaning weight, yearling weight, pre-weaning weight and fleece weight were noted. Year of birth, type of birth, sex, and herd was influenced altogether significantly while, birth weight and greasy fleece weight, the period of birth showed no essential difference. In weaning weight and pre-weaning increment normally, year of birth, sort of birth and herd showed a critical contact except for sex. Male sheep were heavier than female sheep and single conceived sheep were also basically heavier than twins were during offspring birth. Results emulate that the Kajli sheep breed can be improved on through selection and further developed management. The cascade type of influence of the current investigation has levelheaded ramification not just for sheep farming by and by just as for intensified associate of boundaries which definitely convince deviation of weight, weight has become itself essential forecaster of in a matter of seconds wellness results. These outcomes displayed there are complex associations among hereditary qualities and ecological elements of parental, placental and fetal beginning. These are profoundly affected traits by maternal sustenance, genes, be concerned, the executive, environment, occasional diversity of seasons.

Investigation of genetic variability and inbreeding characteristics in a population of Zandi sheep

2008 ◽  
Vol 88 (3) ◽  
pp. 409-417 ◽  
Author(s):  
Farhad Ghafouri-Kesbi ◽  
Moradpasha Eskandarinasab ◽  
Ahmad Hassanabadi
Keyword(s):  
Birth Weight ◽  
Genetic Parameters ◽  
Breeding Value ◽  
Effective Population ◽  
Genetic Progress ◽  
Weaning Weight ◽  
Average Value ◽  
Estimated Breeding Values ◽  
Genetic Trends ◽  
Zandi Sheep

The aim of the present study was to evaluate the genetic parameters and genetics trends for birth and weaning weights, and to quantify the inbreeding characteristics for a population of Zandi sheep. Genetic parameters from both single- and two-trait analyses were estimated using restricted maximum likelihood (REML) with animal models. Genetic trends were estimated by averaging estimated breeding values on year of birth. Full pedigree was analyzed for estimation of inbreeding characteristics. The results obtained confirmed relatively low additive genetic variation in the population, especially for weaning weight. Estimates of direct and maternal heritability were 0.12 and 0.20 for birth weight and 0.08 and 0.02 for weaning weight, respectively. Estimates of breeding value averaged by year of birth for birth weight and weaning weight increased over time. However, there was little genetic progress for birth weight (0.002 kg yr-1), whereas the tendency for weaning weight was 0.020 kg yr-1. Inbred animals consisted of 25% of the population. The effective population size (Ne) was 66 individuals. The inbreeding rate per generation (ΔF) was 0.76%. The average value of inbreeding (F) in the Zandi population was 1.05% and the average relatedness (AR) coefficient reached 1.64% in the whole pedigree. A range of 2.84 to 4.01 yr was obtained for the average generation interval in different pathways. Selection of rams with the lowest AR was recommended for better management of inbreeding and avoidance of relative mating. Key words: Sheep, genetic trends, heritability, inbreeding, average relatedness

scholarly journals Detecting effective starting point of genomic selection by divergent trends from BLUP and ssGBLUP in pigs, beef cattle, and broilers

2021 ◽  
Author(s):  
Rostam Abdollahi Arpanahi ◽  
Daniela Lourenco ◽  
Ignacy Misztal
Keyword(s):  
Birth Weight ◽  
Beef Cattle ◽  
Genomic Selection ◽  
Broiler Chickens ◽  
Average Daily Gain ◽  
Breeding Cycle ◽  
Production Traits ◽  
Weaning Weight ◽  
Daily Gain ◽  
Genetic Trends

Genomic selection has been adopted nationally and internationally in different livestock and plant species. However, understanding whether genomic selection has been effective or not is an essential question for both industry and academia. Once genomic evaluation started being used, estimation of breeding values with pedigree BLUP became biased because this method does not consider selection using genomic information. Hence, the effective start point of genomic selection can be detected in two possible ways including the divergence of genetic trends and Realized Mendelian sampling (RMS) trends obtained with BLUP and Single-step genomic BLUP (ssGBLUP). This study aimed to find the start date of genomic selection for a set of economically important traits in three livestock species by comparing trends obtained using BLUP and ssGBLUP. For this purpose, three datasets comprised a pig dataset with 117k genotypes and 1.3M animals in pedigree, Angus cattle dataset consisted of ~842k genotypes and 11.5M animals in pedigree, and a purebred broiler chicken dataset included ~154k genotypes and 1.3M birds in pedigree were used. The genetic trends for pigs diverged for the genotyped animals born in 2014 for average daily gain and backfat. In beef cattle, the trends started diverging in 2009 for weaning weight and in 2016 for postweaning gain, with little diverging for birth weight. In broiler chickens, the genetic trends estimated by ssGBLUP and BLUP diverged at breeding cycle 6 for two out of three production traits. The RMS trends for the genotyped pigs diverged for animals born in 2014, more for average daily gain than for backfat. In beef cattle, the RMS trends started diverging in 2009 for weaning weight and in 2016 for postweaning gain, with a trivial trend for birth weight. In broiler chickens, the RMS trends from ssGBLUP and BLUP diverged strongly for two production traits at breeding cycle 6, with a slight divergence for another trait. Divergence of the genetic trends from ssGBLUP and BLUP indicates onset of the genomic selection. Presence of trends for RMS indicates selective genotyping, with or without the genomic selection. The onset of genomic selection and genotyping strategies agree with industry practices across the 3 species. In summary, the effective start of genomic selection can be detected by the divergence between genetic and RMS trends from BLUP and ssGBLUP.

scholarly journals Estimation of heritability, breeding values and genetic trends for growth traits of exotic goat

2016 ◽  
pp. 7-11 ◽  
Author(s):  
MR Hassan ◽  
S Sultana ◽  
A Iqbal ◽  
MAI Talukder
Keyword(s):  
Body Weight ◽  
Birth Weight ◽  
Variance Components ◽  
Growth Traits ◽  
Live Weight ◽  
Weaning Weight ◽  
Breeding Values ◽  
Goat Farm ◽  
The Mean ◽  
Genetic Trends

The present study was considered to estimate the variance components, heritability and prediction of breeding values (PBV) for important growth traits of exotic goat. Traits were considered birth weight, weaning weight, 6 months weight and weight at 9 months. Data were collected from the goat farm of Bangladesh livestock research institute (BLRI), Savar, Dhaka. Heritability values for the studied traits were estimated by Multivariate animal model using principles of Restricted Maximum Likelihood (REML) procedure. The mean birth weight, weaning weight, 6 and 9 months weight of exotic goat were recorded as 1.41, 7.39, 11.06 and 14.09 kgs respectively. Calculated Heritability values were 0.33, 0.39, 0.45 and 0.32 for the birth weight, weaning weight, and weight at 6 and 9 month respectively. Heritability estimates for different growth traits of exotic goat were found higher but the highest for the 6 month body weight (0.45). Among the live weight categories of exotic goat the maximum average PBV was found for the 6-month body weight (7.42). The genetic trends among the generations in birth and 6 month weight were increased from foundation to generation 1 and 2. Therefore, the results revealed that the 6 month’s body weight can be considered as an indicator of growth and sire selection and could be effective for enhancing growth of exotic kids.International Journal of Natural Sciences (2013), 3(1-4) 7-11

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