Effects of FecB Mutation on Estrus, Ovulation, and Endocrine Characteristics in Small Tail Han Sheep

The Booroola fecundity gene (FecB) has a mutation that was found to increase the ovulation rate and litter size in Booroola Merino sheep. This mutation is also associated with the fecundity of small-tail han (STH) sheep, an important maternal breed used to produce hybrid offspring for mutton production in China. Previous research showed that the FecB gene affects reproduction in STH sheep, based on litter size records. However, the effects of this gene on estrus, ovulation, and endocrine characteristics in these sheep remain unclear. Here, we analyzed the traits mentioned earlier and compared them among the three FecB genotypes of STH ewes using estrus synchronization. Overall, 53 pluriparous ewes were selected from among 890 STH ewes and subjected to FecB genotyping for experiments to characterize estrous and ovulation rates. FecB heterozygous (+B) ewes presented an earlier onset of estrus (42.9 ± 2.2 h) and a shorter estrous cycle (17.2 ± 0.2 days) (P ≤ 0.05). The ovulation rates increased with the increasing copy number of the B allele (P ≤ 0.01). Ovulation time showed no significant differences among the three FecB genotypes. The serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone, estrogen (E2), and progesterone (P4) were measured in 19 of the ewes. Serum concentrations of E2 and FSH dramatically varied around the time of behavioral estrus. In FecB mutant homozygous (BB) ewes, E2 concentration had two peaks, which were higher (P ≤ 0.05) than those of ++ genotypes. FSH concentration of BB ewes was higher (P ≤ 0.05) than that of the ++ ewes just after estrus. The expression of the estrogen receptor 1 (ESR1) gene in the +B genotype was higher than in the other genotypes. Based on the data for the reproductive performance of STH ewes with the three FecB genotypes, our study suggests that the development of follicles in ewes with the B allele is dependent on the response to FSH regulated by E2 in the early stage. +B ewes, exhibiting moderate ovulation and litter size and a shorter estrous cycle, can be highly recommended in sheep crossbreeding systems for commercial mutton production. Moreover, this study provides useful information to conserve better and use the genetic resources of STH sheep in China.

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The XO and OY chromosome constitutions in the mouse

Genetics Research ◽

10.1017/s0016672300011745 ◽

1968 ◽

Vol 12 (2) ◽

pp. 125-137 ◽

Cited By ~ 84

Author(s):

T. Morris

Keyword(s):

Litter Size ◽

Reproductive Performance ◽

Early Stage ◽

Blastocyst Stage ◽

Embryonic Mortality ◽

Cell Stage ◽

Large Group ◽

Pregnant Females ◽

The Mean

A study was made of reproductive performance and embryonic mortality in XO and XX females. In the stock used, the mean litter size of XO females (4·46) was greatly below that of XX ones (8·17). One series of pregnant females of both karyotypes was dissected after 15 days' gestation, and another series after 3½days' gestation. In the former, there was a significantly greater amount of embryonic mortality in XO females both before implantation and at the small and large mole stages. By far the greater amount occurred before implantation. The data from dissections after 3½ days' gestation concerned pre-implantation embryos, since normal embryos at this point are at the late morula or early blastocyst stage. The embryos from XO females contained a large group of obviously and characteristically abnormal ones; they comprised 60/280 of the embryos from XO females, compared with 4/189 of the XX ones. They appeared to have developed abnormally from a very early stage, probably the two-cell stage, and were considered to represent the missing OY class of zygotes. In addition, it was concluded that there was probably an abnormally low segregation of nullo-X gametes from XO females.

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EFFECTS OF INJECTION OF GONADOTROPIN-RELEASING HORMONE ON SOW FERTILITY

Canadian Journal of Animal Science ◽

10.4141/cjas89-015 ◽

1989 ◽

Vol 69 (1) ◽

pp. 123-129 ◽

Cited By ~ 7

Author(s):

A. D. GOONERATNE ◽

R. N. KIRKWOOD ◽

P. A. THACKER

Keyword(s):

Reproductive Performance ◽

Artificial Insemination ◽

Anterior Pituitary ◽

Intramuscular Injection ◽

Follicle Stimulating Hormone ◽

Gonadotropin Releasing Hormone ◽

Serum Concentrations ◽

Releasing Hormone ◽

Conception Rates ◽

And Control

A total of 159 Landrace × Yorkshire sows were used to study the effects of an intramuscular injection of gonadotropin-releasing hormone (GnRH) at estrus on reproductive performance. Artificial insemination at 24 h or 24 and 40–44 h following treatment, resulted in similar conception rates for GnRH-treated (77.5 and 69.2%) and control sows (70.0 and 67.5%). Conception rates were not affected by insemination regime. GnRH treatment resulted in slightly improved litter sizes in comparison with control sows (10.45 vs 9.92; P > 0.20) whether inseminated once or twice, but had no effect on piglet weight at birth. Litter size and piglet weight at weaning were also not influenced by treatment. GnRH treatment (100 μg) induced increases in serum concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) from the anterior pituitary within 30 min and maximal serum concentrations were observed 90–120 min postinjection. The induced release of both LH and FSH was of short duration (< 4 h), compared to the natural surge of LH which followed later, coincident with estrus. It was concluded that the overall reproductive performance of sows was not significantly influenced by GnRH treatment immediately prior to estrus. Key words: Sow, GnRH, pituitary response, reproductive performance

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The litter size and fertility of Finnish Landrace and Tasmanian Merino sheep and their reciprocal crosses

Animal Science ◽

10.1017/s0003356100022431 ◽

1974 ◽

Vol 18 (3) ◽

pp. 265-271 ◽

Cited By ~ 27

Author(s):

R. B. Land ◽

W. S. Russell ◽

H. P. Donald

Keyword(s):

Litter Size ◽

Direct Effect ◽

Adult Female ◽

Reproductive Performance ◽

Conception Rate ◽

Mating Period ◽

Reciprocal Crosses ◽

Merino Sheep ◽

Size Number

SUMMARYLitter size (number of lambs born per female lambing) of adult female Finnish Landrace and Tasmanian Merino sheep mated to males of either breed was 2·9 and 1·0 respectively. Breed of ram had a direct effect on the conception rate of the ewes to which they were mated—22% of ewes mated to Merino rams returned to oestrus but only 10% of those mated to Finn rams—but not on their litter size.A comparison of the reproductive performance of crossbred females with that of purebred contemporaries indicated that there was very little or no heterosis for litter size, the crossbreds being almost exactly intermediate between the parents. The proportion of females showing oestrus during the mating period, however, was lower in the Merinos than in the Finns and crossbreds. This was particularly noticeable in females put to the ram at around 6 months of age. Whereas 35 of 36 Finnish Landrace females and 46 of 49 crossbreds showed oestrus, only one of the 20 Merinos did so. At about 6 months of age therefore the crossbred females showed heterosis in the incidence of oestrus.

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Effect of estrus synchronization and artificial insemination on reproductive performance of Merino sheep

Brazilian Journal of Veterinary Research and Animal Science ◽

10.1590/s1413-95962002000300006 ◽

2002 ◽

Vol 39 (3) ◽

Cited By ~ 3

Author(s):

Laura Simonetti ◽

Guillermo Ramos ◽

Juan Carlos Gardón

Keyword(s):

Reproductive Performance ◽

Artificial Insemination ◽

Estrus Synchronization ◽

Merino Sheep

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FEEDBACK CONTROL OF FSH IN THE MALE: ROLE OF OESTROGEN

Acta Endocrinologica ◽

10.1530/acta.0.0740449 ◽

1973 ◽

Vol 74 (3) ◽

pp. 449-460 ◽

Cited By ~ 11

Author(s):

Patrick C. Walsh ◽

Ronald S. Swerdloff ◽

William D. Odell

Keyword(s):

Luteinizing Hormone ◽

Follicle Stimulating Hormone ◽

Oestrogen Therapy ◽

Serum Concentrations ◽

Elderly Men ◽

Normal Range ◽

Oestrogen Treatment ◽

Serum Lh ◽

Higher Doses

ABSTRACT Serum follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured by radioimmunoassay in a group of elderly men following castration and oestrogen therapy. Prior to orchiectomy, mean serum concentrations of LH and FSH were within the normal range. Two days following castration, serum LH concentrations increased in all eight patients; higher levels of LH were subsequently measured in all but one patient after periods of time ranging from 49 to 210 days. Serum FSH levels, measured in three patients following castration, increased in a pattern parallel to LH changes. Ethinyl oestradiol (EOe) in doses ranging from 5 to 300 μg/day was administered to ten men who had been castrated 3 to 72 months earlier. Oestrogen treatment suppressed both LH and FSH in a parellel manner in nine of ten patients. LH was first suppressed to intact levels in one of eight patients treated with 20 μg/day of EOe, in two of six patients treated with 50 μg/day, and in one patient by 80 μg/day. FSH was not suppressed to precastration levels until 50 μg/day of EOe was administered; this dose suppressed three of six patients. Higher doses of EOe (150–300 μg/day) suppressed both LH and FSH to levels below the sensitivity of the assay. These data fail to demonstrate any differential effect of oestrogen on LH and FSH release.

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