scholarly journals Reproductive Biology of the Booroola Merino Sheep

1984 ◽  
Vol 37 (3) ◽  
pp. 163 ◽  
Author(s):  
BM Bindon
Keyword(s):  
Reproductive Biology ◽  
Litter Size ◽  
Single Gene ◽  
Ovulation Rate ◽  
Physiological Characteristics ◽  
Merino Sheep ◽  
Sheep Breeds ◽  
The World ◽  
Lamb Survival ◽  
Size At Birth

This paper reviews the genetic and physiological characteristics of the Booroola Merino, one of the four most prolific sheep breeds in the world, and which was acquired by CSIRO in 1958 from a commercial sheep property, 'Booroola', Cooma, N.S.W. The exceptional prolificacy of this genotypee. g. mean flock ovulation rate in 1982 of 4�2 (range 1-10) and mean litter size of 2� 5 (range 1-7)is largely attributable to a single gene (F) of uncertain origin which increases ovulation rate. Crosses of the Booroola with other Merinos produce progeny which have a 47-87% increase in ovulation rate, a 45-56% increase in litter size at birth, and a 1-33% reduction in lamb survival relative to control Merinos. This represents a 16-37% increase in the number of lambs weaned per ewe joined in favour of the Booroola crosses.

THE ACCUMULATIVE EFFECT OF FINNSHEEP BREEDING IN CROSSBREEDING SCHEMES: REPRODUCTIVE PERFORMANCE

1988 ◽  
Vol 68 (1) ◽  
pp. 69-81 ◽  
Author(s):  
MOHAMED H. FAHMY ◽  
JACQUES J. DUFOUR
Keyword(s):  
Body Weight ◽  
Mortality Rate ◽  
Key Words ◽  
Litter Size ◽  
Reproductive Performance ◽  
Conception Rate ◽  
Ovulation Rate ◽  
Genetic Groups ◽  
Linear Regressions ◽  
Size At Birth

Reproductive performance and body weight were studied on 361 ewes, representing Finnsheep (F), DLS (a population of 1/2 Dorset, 1/4 Leicester, 1/4 Suffolk) and seven combinations ranging from 1/8 to 7/8 Finnsheep breeding. Conception rate in yearlings was 61.5% for DLS compared to 89.0% for F with the crosses being intermediate. Conception rate in older ewes was similar in the different genetic groups (avg. 94%). Ovulation rate and litter size at birth of DLS ewes were 1.72 and 1.44 lambs, which was less than half those of F ewes (3.51 and 2.86 lambs, respectively). Both traits increased progressively with an increase in F breeding in crosses and with advances in age. DLS ewes weaned 1.22 lambs compared to 2.03 lambs for F ewes and 1.84 lambs for 4/8 F ewes. The heaviest litters at weaning (31.7 kg) were raised by 4/8 F ewes, followed by 7/8 F (30.8 kg) while those raised by DLS ewes weighed 23.0 kg and F ewes 29.1 kg. Percentage of ova lost per ewe mated averaged 24% and ranged between 18% (DLS and 1/8 F) and 29% (6/8 F). About 3.6% of lambs were born dead and a further 13.8% died before weaning. Preweaning mortality rate was highest in F (22.9%) and lowest in 3/8 F (9.4%). Average kilograms of lambs weaned per ewe exposed was highest in 4/8 F (27.6 kg) followed by F (26.0 kg), whereas that of DLS was the lowest at 18.1 kg. The 4/8 F cross showed 25% heterosis in kg of lambs weaned per ewe exposed and 52.5% increase over DLS. Significant positive linear regressions were calculated for ovulation rate, litter size and preweaning mortality rate on proportion of Finnsheep breeding in crosses. The relation was quadratic for percent ova lost and lamb mortality at weaning. Yearling DLS females weighted 36 kg compared to 44 kg for F yearlings. However, at 5 yr of age DLS ewes weighed 62 kg, 5 kg heavier than F ewes. The heaviest ewes at all ages were the 4/8 F (45 kg at 1 yr, 65 kg at 5 yr). Key words: Reproduction, DLS sheep, Finnsheep, crossbreeding, heterosis, repeatabilities

scholarly journals The status of the Hungarian Merino sheep breed compared to the other merino breeds

2016 ◽  
pp. 151-156
Author(s):  
Mária Szabó ◽  
Szilvia Kusza ◽  
István Csízi ◽  
István Monori
Keyword(s):  
Gene Pool ◽  
Genetic Resource ◽  
Sheep Breed ◽  
The Other ◽  
Drastic Reduction ◽  
Merino Sheep ◽  
Sheep Breeds ◽  
The World ◽  
The Status ◽  
Over Time

Merino and Merino-derived sheep breeds have been widely known and distributed across the world, both as purebred and admixed populations. They represent a diverse genetic resource which over time has been used as the basis for the development of new breeds. In spite of this, their gene-pool potential is still unexplored. The Merino sheep represent the most important sheep resource of the Hungarian husbandry. It has the largest amount of individuals between both of the stock and commercial flocks. But in Europe the Merino stocks went through a drastic reduction in number. Thus these breeds became endangered in several countries as well as in Hungary. In this study we would like to present the recent status of different Merino breeds of the world to ground our further phylogenetic research with the Hungarian Merino breed.

scholarly journals The effects of inbreeding on the components of litter size in mice

1967 ◽  
Vol 10 (1) ◽  
pp. 73-80 ◽  
Author(s):  
J. C. McCarthy
Keyword(s):  
Litter Size ◽  
Inbreeding Depression ◽  
First Generation ◽  
Inbreeding Coefficient ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Base Population ◽  
Pregnant Females ◽  
Sib Mating ◽  
Size At Birth

Twenty-four lines were bred from a base population of outbred Q mice by continued full-sib mating. Inbreeding depression in litter size at birth was observed. This decline in litter size was analysed in terms of ovulation rate, the incidence of preimplantation mortality and the incidence of postimplantation mortality. Pregnant females were dissected at 17½ days' gestation and the numbers of corpora lutea, or eggs, and of live and dead embryos were counted. Matings were arranged so that separate estimates of the effects of inbreeding in the mother and in the litter on the components of litter size could be obtained.In the first generation of inbreeding when the inbreeding coefficient of the litter was raised from 0 to 25% decline in litter size was attributable to an increased incidence of preimplantation mortality.In the second and fourth generations decline in litter size was attributable to (1) a reduction in the number of eggs ovulated by the inbred mothers, (2) an increased incidence of preimplantation mortality which resulted from inbreeding in the mother. No evidence of significant effects on mortality of inbreeding in the litter was obtained in the later generation of inbreeding.These findings are discussed in the context of previous work on the effects of inbreeding and crossing on litter size and its components in mice and pigs.

scholarly journals Erratum to: Investigation on early growth traits, litter size, and lamb survival in two Iranian fat-tailed sheep breeds

2012 ◽  
Vol 45 (4) ◽  
pp. 1055-1055
Author(s):  
Hadi Atashi ◽  
Jamshid Izadifard ◽  
Mohammad Javad Zamiri ◽  
Amir Akhlaghi
Keyword(s):  
Litter Size ◽  
Growth Traits ◽  
Early Growth ◽  
Sheep Breeds ◽  
Lamb Survival

scholarly journals Comparison of performance of F1 Romanov crossbred ewes with wool and hair breeds during fall lambing and body weight and longevity through 6 production years

2020 ◽  
Author(s):  
T W Murphy ◽  
B A Freking
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Total Weight ◽  
Breed Differences ◽  
Lamb Survival ◽  
Sire Breed ◽  
Maternal Grandsire ◽  
Size At Birth ◽  
Birth Type

Abstract Objective was to evaluate wool (Dorset and Rambouillet) and hair (Dorper, Katahdin, and White Dorper) breeds for their ability to complement Romanov germplasm in an annual fall lambing system by estimating direct maternal grandsire and sire breed effects on economically important lamb and ewe traits. After 3 yr of evaluation under spring lambing, ewes of the 5 F1 types were transitioned to spring mating, exposed to composite terminal sires, and evaluated under a barn lambing system at 4, 5, and 6 yr of age. A total of 527 F1 crossbred ewes produced 1151 litters and 2248 lambs from 1378 May exposures. After accounting for differences in dam age, birth type, and sex, lamb survival to weaning was unaffected by maternal grandsire breed (P = 0.30). However, lambs born to 50% Dorset (16.8 ± 0.21 kg) or 50% White Dorper ewes (16.8 ± 0.28 kg) were heavier at weaning than those born to 50% Katahdin dams (13.8 ± 0.32 kg; P < 0.001). Additionally, lambs born to 50% Dorset ewes were heavier than those born to 50% Rambouillet (16.0 ± 0.22 kg) and 50% Dorper ewes (15.7 ± 0.33; P ≤ 0.03), but no other pairwise maternal grandsire breed differences were observed (P ≥ 0.06). Ewe body weight (n = 3629) was recorded prior to each of 6 possible mating seasons and, across ages, was greatest for Dorset and Rambouillet sired ewes (56.7 ± 0.44 and 56.5 ± 0.45 kg, respectively), intermediate for Dorper and White Dorper sired ewes (54.7 ± 0.78 and 54.1 ± 0.64 kg, respectively), and least for Katahdin sired ewes (51.5 ± 0.45 kg). Fertility after spring mating (0.80 ± 0.03 to 0.87 ± 0.02), litter size at birth (1.46 ± 0.09 to 1.71 ± 0.07), and litter size at weaning (1.25 ± 0.06 to 1.46 ± 0.06) were not impacted by sire breed (P ≥ 0.16). Ewe longevity, assessed as the probability of being present after 6 production years, was also not affected by sire breed (0.39 ± 0.03 to 0.47 ± 0.03; P = 0.44). Rambouillet sired ewes weaned more total weight of lamb (21.5 ± 0.94 kg) than Katahdin sired ewes (17.8 ± 0.94 kg; P = 0.05), but no other sire breed differences were detected (P ≥ 0.07). Results demonstrated that incorporating the Romanov into a crossbreeding system is a practical means of improving out-of-season ewe productivity.

Investigation in early growth traits, litter size, and lamb survival in two Iranian fat-tailed sheep breeds

2012 ◽  
Vol 45 (4) ◽  
pp. 1051-1054 ◽  
Author(s):  
Hadi Atashi ◽  
Jamshid Izadifard ◽  
Mohammad Javad Zamiri ◽  
Amir Akhlaghi
Keyword(s):  
Litter Size ◽  
Growth Traits ◽  
Early Growth ◽  
Sheep Breeds ◽  
Lamb Survival

scholarly journals Ovulation rate and early embryonic survival rate in female rabbits of a synthetic line and a local Algerian population

2016 ◽  
Vol 24 (4) ◽  
pp. 275 ◽  
Author(s):  
R. Belabbas ◽  
M.L. García ◽  
H. AinBaziz ◽  
A. Berbar ◽  
G. Zitouni ◽  
...  
Keyword(s):  
Survival Rate ◽  
Litter Size ◽  
Local Population ◽  
Ovulation Rate ◽  
Lower Percentage ◽  
Embryonic Survival ◽  
Stage Of Development ◽  
Algerian Population ◽  
Size At Birth ◽  
Synthetic Line

<p>A higher litter size at birth has been reported in female rabbits from a Synthetic line than in those of the Local Algerian population. The aim of this work was to analyse whether this difference in litter size was due to a higher ovulation rate and/or embryonic survival rate in Synthetic line than in Local Algerian population. In total, 24 multiparous female rabbits from Synthetic line and 23 from Local population were used in this experiment. Litter size at birth was recorded up to the first 3 parities. Litter size was 20% higher in Synthetic line than Local population. At their 4th gestation, the females were euthanized at 72 h post coitum. Synthetic line females had 50% more ova and embryos than those of Local population (+4.42 ova and +3.92 embryos, respectively). Synthetic line displayed a lower percentage of normal embryos and a larger number of unfertilized oocytes than Local population (–2.81% and +0.64 oocytes, respectively), but differences were not relevant. Synthetic line showed a lesser embryonic stage of development at 72 h post coitum, showing a higher percentage of early morulae (31.50 vs. 8.50%) and a lower percentage of compact morulae (51.45 vs. 78.65%) than Local population. No relevant difference was found for early embryonic survival rate between Synthetic line and Local population. In conclusion, the difference in litter size was mainly due to a higher ovulation rate in the Synthetic line, allowing more embryos to develop in this line.</p>

Performance of crossbred progeny of Trangie Fertility Merino and Booroola Merino rams and Poll Dorset ewes. 3. Reproduction, liveweight and wool production of adult ewes

1995 ◽  
Vol 35 (8) ◽  
pp. 1083 ◽  
Author(s):  
NM Fogarty ◽  
DG Hall
Keyword(s):  
Birth Weight ◽  
Litter Size ◽  
Significant Variation ◽  
Ovulation Rate ◽  
Average Birth Weight ◽  
Wool Production ◽  
Component Traits ◽  
Lamb Survival ◽  
Fleece Weight ◽  
Almost All

Reproduction, liveweight and wool production are reported for 4 cohorts of 377 Trangie Fertility x Dorset (TD) and 261 Booroola x Dorset (BD) ewes over 6 years. The BD ewes were 3-4 kg lighter (P<0.001) and had a higher ovulation rate prior to joining in February-March (2.37 � 0.03 v. 1.65 � 0.03) than TD ewes. This resulted in a higher litter size (2.07 � 0.03 v. 1.66 � 0.04) and number of lambs born per ewe joined (1.92 � 0.04 v. 1.56 � 0.04) for the BD ewes. Lamb survival was lower from BD than TD ewes (0.71 � 0.02 v. 0.85 � 0.02), so that the 2 ewe strains weaned the same number of lambs. The growth rate of lambs was lower from the BD ewes and overall they weaned 3.8 kg less (P<0.001) weight of lamb than TD ewes. Chill (index of environmental conditions at lambing), litter size and average birth weight of lambs in the litter (linear and quadratic) affected (P<0.001) lamb survival. At moderate levels of chill there was little difference in survival of single and twin lambs from BD and TD dams when birth weight was 4-5 kg, but survival declined more rapidly for progeny of BD ewes at lower birth weight. Under severe lambing conditions survival was depressed more for lambs born from BD ewes than TD ewes. Almost all ewes expressed oestrus over the 3, 6-week periods, December-January, January-February and March (joining). There was significant variation (P<0.001) in incidence of oestrus due to year and age (linear and non-linear), but not liveweight at joining, and there was little difference between ewe strains. Similarly, for post-lambing oestrus (to fit 8-monthly joining) and post-lambing anoestrous interval, there was little difference between strains, but year and age were highly significant (P<0.001). BD ewes had a lower (P<0.001) greasy fleece weight (3.76 v. 3.86 kg), than TD ewes. BD ewes were classified as either carriers (F+) or non-carriers (++) of the FecB gene, which was significant (P<0.001) for ovulation rate (+1.14 ovulations), litter size (+0.8 lambs), lamb survival (-18%), lambs born per ewe joined (+0.64 lambs) and total weight of lamb born per ewe joined (0.5 kg, P<0.01). The effect of the FecB gene was non-significant for lamb survival when litter size and lamb birth weight (P<0.001) were included in the model. Repeatability estimates based on over 3 records per ewe were about 0.2 for lambs born, weight of lamb born, lambs weaned and weight of lamb weaned per ewe joined. Component traits ranged from 0.27 for litter size to 0.10 for lamb survival, with fertility intermediate (0.15). Greasy fleece weight (0.72) and ovulation rate (0.41) had high repeatabilities with post-lambing anoestrous interval being low (0.11). Repeatability for ovulation rate was reduced to 0.34 when F+ ewes were excluded.

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