scholarly journals Variation in ovulation rate and litter size

1988 ◽  
Vol 60 (6) ◽  
pp. 602-602
Author(s):  
G. E. Bradford ◽  
Y. M. Berger
Keyword(s):  
Litter Size ◽  
Production Systems ◽  
Major Gene ◽  
Ovulation Rate ◽  
Intensive Management ◽  
Coefficients Of Variation ◽  
Sheep Production

An increase in mean prolificacy is a goal for many sheep production systems, but it is also desirable that variation be minimized around the optimum value. Lambs born in litters of 3 or 4 can be reared with intensive management, but at higher input costs than for twins. Thus for a mean litter size (LS) goal of 2.0, producers desire the maximum possible proportion of twins with as few singles and litters of 3 or more as possible. Coefficients of variation for ovulation rate (OR) range from about 22 % for Romanov to about 40 % for Booroola Merinos; breed CV’s for LS vary less. The most uniform LS’s are achieved by populations with a uniform OR and high prenatal survival. Variability in Booroola populations results in part from segregation of a gene with large effect on OR, but variation is high within genotypes (FF or F+). Among breeds where high prolificacy appears to be inherited quantitatively, there are differences in variability, with Romanov quite uniform, Finnsheep intermediate, and D’Man more variable. The possibility of a gene with large effect in the D’Man breed, in addition to many favorable quantitative genes for prolificacy, has not been ruled out. In general, these three breeds (and some others) transmit their prolificacy additively, making it possible to choose a wider range of mean prolificacy values by crossing and backcrossing with such breeds than by use of a major gene such as the Booroola. Data on variability of first and later generation crossbreds between non-prolific and different prolific breeds are now available.

scholarly journals The Cambridge sheep — its exploitation for increased efficiency of lamb production

1988 ◽  
Vol 60 (6) ◽  
pp. 585-590
Author(s):  
J. B. Owen ◽  
I. AP Dewi
Keyword(s):  
Litter Size ◽  
Large Range ◽  
Major Gene ◽  
Ovulation Rate ◽  
Gene Effect ◽  
Generation Interval ◽  
Major Gene Effect ◽  
Feed Utilisation ◽  
Relationship Of ◽  
The Relationship

The Cambridge breed has been developed since 1964, based on a foundation group of 54 ewes representing 11 breeds mated initially to seven Finnsheep rams. Data presented show that a high litter size(LS) has been established (mean 2.8 in 3 year old ewes) by a policy of selection coupled with minimising generation interval. Observations on ovulation rate (OR)show a large range (1—13) and are consistent with an hypothesis that OR is influenced by a major gene effect superimposed on a basal level of about 2.5 ova. The gene appears to increase ovulation by about two ova per copy and to have a frequency approaching 0.3 in the Bangor University flock. Data on the relationship of LS at birth and of lambs weaned per ewe are presented which indicate that under ideal conditions the optima for OR and LS at birth cannot exceed 5 and 3.5 respectively for mature ewes. The practical utilisation of the breed as a dam-line sire of crossbred ewes show that the Cambridge crossbreds are more precocious, more prolific, have slower growing lambs with carcasses of similar quality to the corresponding Border Leicester crosses. Overall superiority inefficiency of feed utilisation is about 20 %. Methods of genotyping sheep and utilising the major gene in practice are discussed.

Variation in progeny performance of prolific ewes of extreme phenotype

1995 ◽  
Vol 1995 ◽  
pp. 47-47
Author(s):  
I. Ap Dewi ◽  
J.B. Owen ◽  
R.F.E. Axford ◽  
J.P. Hanrahan
Keyword(s):  
Litter Size ◽  
Major Gene ◽  
Ovulation Rate ◽  
Extreme Phenotype ◽  
Progeny Performance

The presence of a major gene influencing prolificacy has been proposed for the Cambridge breed. Cambridge ewes of extreme phenotype were identified by ovulation rate (OR) and litter size (LS) recorded in a single flock from 1976-1994. Means (sd) for all observations for OR (n=2062) and LS (n=2480) were 3.0 (1.69) and 2.5 (1.02). Extreme ewes were identified by three criteria: (a) High prolificacy had at least one OR observation ≥6; (b) Low prolificacy had records in at least three years with no OR or LS record >3; (c) Ewes had progeny with records in at least three years. On the basis of these criteria 27 High and 67 Low ewes were identified with 1.6 and 1.5 progeny per ewe, 2.1 and 2.5 OR records per progeny, and 3.7 and 1.7 LS records per progeny. The OR and LS results for ewes and their progeny are shown in Table 1. The maximum observed OR of High ewes ranged from 6-13 and both the OR and LS of Low ewes had a mean of 2.2 and ranged from 1-3. Means (se) of the progeny of the High and Low groups (determined in a model that included dam group, progeny within group, year and progeny age) were 3.9 (0.19) and 3.0 (0.13) for OR (P=0.003), and 2.6 (0.12) and 2.4 (0.11) for LS (P=0.055).

scholarly journals Polymorphism Detection of GDF9 Gene and Its Association with Litter Size in Luzhong Mutton Sheep (Ovis aries)

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 571
Author(s):  
Fengyan Wang ◽  
Mingxing Chu ◽  
Linxiang Pan ◽  
Xiangyu Wang ◽  
Xiaoyun He ◽  
...  
Keyword(s):  
Litter Size ◽  
Tertiary Structure ◽  
Novel Mutation ◽  
Major Gene ◽  
Ovis Aries ◽  
Nucleotide Polymorphisms ◽  
Economic Traits ◽  
Coding Region ◽  
Association Analyses ◽  
Gdf9 Gene

Litter size is one of the most important economic traits in sheep. GDF9 and BMPR1B are major genes affecting the litter size of sheep. In this study, the whole coding region of GDF9 was sequenced and all the SNPs (single nucleotide polymorphisms) were determined in Luzhong mutton ewes. The FecB mutation was genotyped using the Sequenom MassARRAY®SNP assay technology. Then, the association analyses between polymorphic loci of GDF9 gene, FecB, and litter size were performed using a general linear model procedure. The results showed that eight SNPs were detected in GDF9 of Luzhong mutton sheep, including one novel mutation (g.41769606 T > G). The g.41768501A > G, g.41768485 G > A in GDF9 and FecB were significantly associated with litter size in Luzhong mutton ewes. The g.41768485 G > A is a missense mutation in the mature GDF9 protein region and is predicted to affect the tertiary structure of the protein. The results preliminarily demonstrated that GDF9 was a major gene affecting the fecundity of Luzhong mutton sheep and the two loci g.41768501A > G and g.41768485 G > A may be potential genetic markers for improving litter size.

Evaluation of a new technology when applied to sheep production systems: Part I—Model description

1989 ◽  
Vol 29 (1) ◽  
pp. 35-47 ◽  
Author(s):  
P.J. Bowman ◽  
D.A. Wysel ◽  
D.G. Fowler ◽  
D.H. White
Keyword(s):  
Production Systems ◽  
New Technology ◽  
Model Description ◽  
Sheep Production

The effects of dietary fibre and puberty induction method on ovarian activity of gilts

1996 ◽  
Vol 1996 ◽  
pp. 145-145
Author(s):  
V L Glasgow ◽  
A H Stewart ◽  
S A Edwards
Keyword(s):  
Litter Size ◽  
Dietary Fibre ◽  
Ovulation Rate ◽  
Ovarian Activity ◽  
Induction Method ◽  
High Level

In commercial systems it is highly desirable that gilts are synchronised into a predictable first heat. The use of PMSG/hCG injections (PG 600) has met with some success inducing a synchronised fertile oestrus and slightly increased ovulation rate (Schilling and Cerne, 1972) in gilts and anoestrus sows. Diets containing a high proportion of dietary fibre may influence litter size in gilts (Stewart et al, 1995). The aim of this study was to determine the effect of a high level of dietary fibre on oestrus expression and ovulation rate of gilts synchronised with exogenous gonadotrophins (PG600) or given daily boar stimulus.

scholarly journals Carcass and meat lamb and kid quality and development of consumer acceptability

2008 ◽  
Vol 37 (spe) ◽  
pp. 143-160 ◽  
Author(s):  
Carlos Sañudo Astiz
Keyword(s):  
Production Systems ◽  
Ageing Time ◽  
Small Ruminants ◽  
Consumer Acceptability ◽  
Meat Production ◽  
World Population ◽  
Local Market ◽  
Artificial Fibre ◽  
Human World ◽  
Sheep Production

Small ruminants have been one of the first domesticated species and from their origins have produced multiple benefits to humans. In the last two centuries, world sheep production has become more and more specialised upon geographical areas. But, recent changes in consumer attitudes, together with the increment in artificial fibre industries and human world population, some crisis related with the international wool market and some increments in lamb prices, have provoked that lamb meat has increased its relative importance inside the global sheep income. Also, sheep production systems vary considerably across the world, and reflect the different local environmental conditions, which determine, to a large extent, breeds, housing, levels of intensification and, at the end, local market requirements and qualities. However, among all the meats, sheep meat remains the most internationally traded (16 % of total world production is exported), which explains the potential existence of different lamb products in the same market. Then, the new requirements have created a higher interest for meat production, including its quality and quality marks. This interest from producers and the industry should be reflected in a proportional higher interest from the researches towards sheep and goat, where it exists, in general, important lacks of knowledge and, in particular, in lamb and kid meat Science. In the present speech we will made a special incidence on the relationship between carcass quality and lamb acceptability and on some factors like breed and species, diet and production system, slaughter weight and ageing time and their importance on the variation of the carcass and meat quality, including consumer acceptability.

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 Active immunization against the proregions of GDF9 or BMP15 alters ovulation rate and litter size in mice

Reproduction ◽  
2012 ◽  
Vol 143 (2) ◽  
pp. 195-201 ◽  
Author(s):  
C Joy McIntosh ◽  
Steve Lawrence ◽  
Peter Smith ◽  
Jennifer L Juengel ◽  
Kenneth P McNatty
Keyword(s):  
Litter Size ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Cross Reactivity ◽  
Full Length ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Immunization Group

The transforming growth factor β (TGFB) superfamily proteins bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9), are essential for mammalian fertility. Recent in vitro evidence suggests that the proregions of mouse BMP15 and GDF9 interact with their mature proteins after secretion. In this study, we have actively immunized mice against these proregions to test the potential in vivo roles on fertility. Mice were immunized with either N- or C-terminus proregion peptides of BMP15 or GDF9, or a full-length GDF9 proregion protein, each conjugated to keyhole limpet hemocyanin (KLH). For each immunization group, ovaries were collected from ten mice for histology after immunization, while a further 20 mice were allowed to breed and litter sizes were counted. To link the ovulation and fertility data of these two experimental end points, mice were joined during the time period identified by histology as being the ovulatory period resulting in to the corpora lutea (CL) counted. Antibody titers in sera increased throughout the study period, with no cross-reactivity observed between BMP15 and GDF9 sera and antigens. Compared with KLH controls, mice immunized with the N-terminus BMP15 proregion peptide had ovaries with fewer CL (P<0.05) and produced smaller litters (P<0.05). In contrast, mice immunized with the full-length GDF9 proregion not only had more CL (P<0.01) but also had significantly smaller litter sizes (P<0.01). None of the treatments affected the number of antral follicles per ovary. These findings are consistent with the hypothesis that the proregions of BMP15 and GDF9, after secretion by the oocyte, have physiologically important roles in regulating ovulation rate and litter size in mice.

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