scholarly journals Annual characteristics of estrous activity in wool and hair ewe lambs under subtropical conditions

2007 ◽  
Vol 64 (5) ◽  
pp. 468-475 ◽  
Author(s):  
Paula de Almeida Rodrigues ◽  
Lia de Alencar Coelho ◽  
Keico Okino Nonaka ◽  
Aya Sasa ◽  
Wilter Ricardo Russiano Vicente ◽  
...  
Keyword(s):  
Estrous Cycle ◽  
Breeding Season ◽  
Activity Pattern ◽  
Continuous Distribution ◽  
Reproductive Activity ◽  
Estrous Cycles ◽  
Southeast Brazil ◽  
Ewe Lambs ◽  
Santa Inês ◽  
Autumn And Winter

The increased emphasis placed on lamb production in Brazil points to the need for a better knowledge of the annual pattern of reproductive activity in ewe lambs. This study evaluates the annual estrous activity pattern of hair and wool ewe lambs raised in southeast Brazil. Estrous characteristics were recorded for 12 months in ten Santa Inês and 21 Romney Marsh and Suffolk ewe lambs. Santa Inês ewe lambs exhibited a greater length of the normal estrous cycle (14 to 19 days) than Romney Marsh and Suffolk ewe lambs (17.0 ± 0.1 days vs. 16.5 ± 0.2 and 15.9 ± 0.2 days). All the ewe lambs presented a greater number of periods of estrus per animal per month for single estrous cycles (up to 26 days) during autumn and winter. During spring and summer there was a reduction of this number but this decline varied according to the breed. For Santa Inês ewe lambs the reduction was only significant in the summer. For wool ewe lambs the reduction was significant in both seasons but was more accentuated for Romney Marsh. The Romney Marsh ewe lambs had a more restricted breeding season than Suffolk and both presented optimal estrus activity in autumn and winter. Santa Inês ewe lambs had a continuous distribution of estrous cycles along the year, although presenting a reduction in the number of estrous periods in the summer. The ewe lambs of three breeds presented characteristics of sexual immaturity, like irregular estrous cycles and silent ovulations.

Can advance of first lambing induced by melatonin implants influence the next lambing time in Sarda breed sheep?

2012 ◽  
Vol 92 (1) ◽  
pp. 67-71 ◽  
Author(s):  
Vincenzo Carcangiu ◽  
Maria Consuelo Mura ◽  
Pier Paolo Bini ◽  
Giuseppe Massimo Vacca ◽  
Cinzia Daga ◽  
...  
Keyword(s):  
Breeding Season ◽  
Slow Release ◽  
Reproductive Activity ◽  
First Year ◽  
Melatonin Treatment ◽  
Ewe Lambs ◽  
Second Year ◽  
Single Implant ◽  
Breed Sheep ◽  
Short Days

Carcangiu, V., Mura, M. C., Bini, P. P., Vacca, G. M., Daga, C. and Luridiana, S. 2012. Can advance of first lambing induced by melatonin implants influence the next lambing time in Sarda breed sheep? Can. J. Anim. Sci. 92: 67–71. In adult sheep, exogenously administered melatonin from continuous slow-release implants has been shown to advance the onset of the breeding season by mimicking the stimulatory effect of short days. The aim of this study was to verify if treatment with one or two melatonin implants was effective in advancing the first conception in Sarda ewe lambs, and if this advance would also be seen in the second lambing too. In the first year, 600 ewe lambs were randomly assigned to groups M, M+M and C, each with 200 animals. On Jun. 30, group M received a single implant while group M+M received two implants. Group C was untreated. On Aug. 04, 25 rams were introduced in the groups and removed after 70 d. From these 600 animals the 420 head that lambed prior to Mar. 12 were chosen for the second year. These ewes were subdivided into two groups T1 (ewes who lambed between 2007 Jan. 01 and Feb. 10) and T2 (ewes which lambed between 2007 Feb. 11 and Mar. 12). Both in T1 and T2 the distribution of the animals in M, M+M and C group was maintained. In the first year, the treated animals lambed earlier (P<0.05) and showed higher numbers of lambed ewes at Feb. 10 (P<0.01) and at March 12 (P<0.05) compared with untreated control animals. The animals that showed an advance in the period of their first conception, also showed, in the second breeding year, an advance in the lambing time (P<0.001). This study provides evidence that the advance of first conception, obtained with melatonin treatment also influenced the reproductive activity in the following breeding season.

A note on attainment of puberty of september-born early-maturing ewe lambs in relation to level of nutrition

1991 ◽  
Vol 53 (3) ◽  
pp. 407-409 ◽  
Author(s):  
F. Forcada ◽  
J. A. Abecia ◽  
L. Zarazaga
Keyword(s):  
Sexual Activity ◽  
Breeding Season ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Plasma Progesterone ◽  
Ewe Lambs ◽  
Early Maturing ◽  
Age At Puberty

The attainment of puberty in September-born early-maturing ewe lambs was studied at Zaragoza (latitude 41° 40' N). Thirty twin Salz females were allocated to two groups receiving two nutrition levels after 3 months of age: high (500 g/day lucerne hay and 500 g/day concentrate) (H) and low (500 g/ day lucerne hay) (L). Oestrus was detected daily by aproned rams. Corpora lutea were counted after oestrus and plasma progesterone levels monitored each week.In the first breeding season (January to February) the percentage of females showing sexual activity (silent emulation or oestrus and ovulation) was higher in the H compared with the L group (67 and 20%; P < 0/05). Nonpubertal oestrus before the main breeding season was detected in 67% of animals. In the main breeding season and for H and L groups respectively, percentage of females showing silent ovulation before puberty was 67 and 33% and mean age at puberty extended to 319 (s.e. 4-8) and 314 (s.e. 3·7) days. Ovulation rate at puberty was 1·73 (s.e. 0·13) and 1·33 (s.e. 0·15) respectively (P < 0·05).

THE DURATION OF THE BREEDING SEASON OF FOUR BREEDS OF SHEEP

1974 ◽  
Vol 54 (3) ◽  
pp. 389-392 ◽  
Author(s):  
J. J. DUFOUR
Keyword(s):  
Sexual Activity ◽  
Breeding Season ◽  
Estrous Cycles ◽  
Progressive Decline ◽  
Daily Exposure ◽  
Almost All

Three breeds of sheep (Dorset, Leicester, and Suffolk) and a crossbred line from these breeds (DLS) were observed throughout 1 yr to determine their sexual activity by daily exposure of the ewes to vasectomized rams. The DLS and Dorset ewes exhibited their first estrus earlier in the year (P < 0.01) and stopped cycling later than the Leicester and Suffolk ewes (P < 0.01). The duration of the breeding season in the DLS ewes was 20 days (P > 0.05) longer than in the Dorsets and 70 and 115 days (P < 0.01) longer than in the Leicester and Suffolk ewes, respectively. The percentage of Dorset and DLS ewes showing one or more estrous periods increased progressively from June to reach 100% in September for both breeds. The Suffolk and Leicester ewes commenced to cycle in late August and by September almost all ewes had shown an estrous period. The progressive decline in estrous activity became evident first with the Suffolk in January, then with the Dorset and Leicester in February and with the DLS in March. The Dorset, DLS and Leicester ewes had longer estrous cycles than the Suffolk ewes. Within ewes, length of estrous cycles was highly repeatable for all breeds. False estrus and silent estrus occurred in 1.0 and 3.9% of the estrous periods, respectively. Over successive estrous cycles, length of estrous cycles increased significantly.

The effect of stage of breeding season or pre-mating oestrogen and progestagen therapy on fertility in ewe lambs

1994 ◽  
Vol 59 (3) ◽  
pp. 429-434 ◽  
Author(s):  
N. F. G. Beck ◽  
M. C. G. Davies
Keyword(s):  
Breeding Season ◽  
Corpora Lutea ◽  
Oestrogen Therapy ◽  
Crown Rump Length ◽  
Ewe Lambs ◽  
Oestradiol Benzoate

AbstractAn investigation was conducted to determine the effect of mating at puberty or third oestrus or after pre-mating oestrogen and progestagen therapy, designed to mimic the changes that occur in plasma oestrogen and progesterone concentrations during the 1st, 2nd or 3rd oestrous cycles, on fertility in ewe lambs. Twenty-five ewe lambs were mated at puberty on mean date of 18 October and 21 were mated at third oestrus on 3 December. Of these, 28% and 81% of animals mated at puberty and third oestrus lambed, respectively (P < 0·05). A similar number of ewe lambs were mated within 24 h of ram introduction in the groups given one, two or three consecutive applications oestrogen and progestagen (25 μg oestradiol benzoate followed 48 h later by a progestagen pessary left in situ for days). Of the 43 corpora lutea, 21 were represented by viable embryos in the 37 animals holding to service after one application compared with 34 out of 46 corpora lutea in 40 animals given three applications (P < 0·05). Furthermore, embryo crown-rump length, embryo weight and amniotic sac width was greater (P < 0·05), on day of pregnancy, in animals given one compared with three applications of oestrogen and progestagen. These results demonstrate that fertility is improved in ewe lambs mated on third oestrus or after progestagen and oestrogen therapy designed to simulate three oestrous cycles.

scholarly journals AUTUMN AND WINTER LAMBING STRATEGIES IN NORTHLAND

1986 ◽  
pp. 81-87
Author(s):  
W.G.K. Andrewes ◽  
A.O. Taylor
Keyword(s):  
Low Cost ◽  
Breeding Programme ◽  
Management Options ◽  
Mating Ability ◽  
Ewe Lambs ◽  
Sheep Production ◽  
Autumn And Winter

Progress in the development of autumn and winter lambing systems in Northland is described. Both involve split flock lambing in which 30 or 15% of ewes lamb in autumn or winter respectivelv, the remainder in spring. Using progesterone priming, a high ram to ewe ratio (10%) and ram management, 80.90% of ewes joined lamb over 2 cycles. Winter lambing using cull ewes is simple and does not require a breeding programme. Ewes and their lambs can be sent to the meat works from September. For low cost lamb production with present breeds, autumn lambing requires a breeding programme to develop spring mating ability. Heavyweight(18kg)carcasses can be produced early in the killing season. Autumn born replacement ewe lambs consistently averaged 40kg before their first summer. Both systems offer more flexibility in sheep production on farms and in processing and marketing. Keywords: Autumn lambing, winter lambing, split lambing, management options, extending killing season, heavyweight lambs production

scholarly journals 247GENE EXPRESSION OF MAMMALIAN RELATIVE OF DNAJ IN BOVINE ENDOMETRIUM DURING EARLY PREGNANCY

2004 ◽  
Vol 16 (2) ◽  
pp. 244
Author(s):  
K. Oshima ◽  
T. Kojima ◽  
H. Watanabe ◽  
M. Fukushima ◽  
O. Dochi ◽  
...  
Keyword(s):  
Estrous Cycle ◽  
Internal Standard ◽  
Rnase H ◽  
Taqman Probe ◽  
Relative Level ◽  
Estrous Cycles ◽  
Total Rna ◽  
Method Of Calculation ◽  
Design Software ◽  
Shock Proteins

The mammalian relative of DNAJ (MRJ), a member of the molecular chaperones that are known as heat shock proteins, plays an important role in the process of murine chorioallantoic fusion. The objective of this study was to determine the expression pattern of MRJ in the bovine endometrium during early and mid-pregnancy using quantitative RT-PCR. Twenty-eight Japanese Black cows, aged between 1.2 and 15.2 years, with normal estrous cycles, were used in this study. Twenty-one cows were used for study of the level of MRJ during pregnancy. They were artificially inseminated, and their endometrial tissues were collected on Days 16 to 21 (n=7), 30 to 36 (n=6), 48 to 49 (n=4) and 74 to 140 (n=4) of pregnancy. Seven cows were used as controls for the study of cyclic level of MRJ, and their endometrial tissues were collected on Days 13 to 14 (n=4) and 17 to 20 (n=3) of the estrous cycle. The caruncles and the intercaruncles were isolated from the endometrial tissues. All tissues were frozen immediately using liquid nitrogen. Total RNA from these samples was extracted from the tissue using Trizol (Invitrogen Corp., Carlsbad, CA, USA). The first strand of cDNA was synthesized from the total RNA by oligo (dT)12–18 and SuperScript™ II RNase H- Reverse Transcriptase (Invitrogen Corp.) according to the manufacturer’s instructions. Primers and the TaqMan probe for MRJ and glyceraldehyde-phosphate-dehydrogenase (GAPDH) were designed using the primer design software Primer Express™ (Applied Biosystems, Foster City, CA, USA). Bovine GAPDH was used as an internal standard. All PCR reactions were performed using a TaqMan™ PCR Reagent Kit and a MicroAmp Optical 96-Well Reaction Plate and Cap (Applied Biosystems). The assay used an ABI Prism 7700 Sequence Detector (Applied Biosystems). Signals were detected according to the manufacturer’s instructions. The relative level of MRJ expression was calculated on the basis of GAPDH quantity (the method of calculation: relative level=MRJ quantity/GAPDH quantity). Data were analyzed by one-way ANOVA, and means were conpared by Tukey-Kramer’s HSD test. Mammalian relative of DNAJ genes were expressed in all samples examined;; the levels in intercaruncle tended to be greater than those in caruncle. Although MRJ expression level at Days 16 to 21 of pregnancy was greater than at other days during pregnancy, there were no significant differences between the levels at Days 16 to 21 of pregnancy and those of the estrous cycle. These results suggest that MRJ is produced in the endometrium and may play a role in early and mid-pregnancy and the estrous cycle.

Effect of Clomiphene Citrate and Letrozole on Body Weight of female Albino Rat for Consecutive 1-4 Estrous Cycles

2021 ◽  
Vol 15 (11) ◽  
pp. 2938-2941
Author(s):  
Fauzia Qureshi ◽  
Syeda Rizwana Jafri ◽  
Hafiza Sadia Ahmad ◽  
Uzma Waseem ◽  
Ursula Akif ◽  
...  
Keyword(s):  
Body Weight ◽  
Estrous Cycle ◽  
Ovulation Induction ◽  
Clomiphene Citrate ◽  
The Body ◽  
Control Group ◽  
Albino Rats ◽  
Albino Rat ◽  
Estrous Cycles ◽  
Experimental Group

Background: Ovulation induction with clomiphene citrate in women with infertility has been practiced more than 40% years but in infertile patients this treatment plan proved to be ineffective with multiple complication. Body weight plays an important role modulating reproductive development and functioning. Aim: To observe the effects on body weight of female albino rat after use of clomiphene citrate and letrozole for consecutive 1-4 estrous cycles Method: Eighty four adult female Albino rats were equally divided into three groups for this research. Body weight of each rat was measured before and after the experiment. Vaginal smear cytology of each rat was performed to study different phases of estrous cycle. Control group A was given normal saline orally , In Experimental group B rats were given letrozole (Femara) at dose 5mg/kg orally and in Experimental group C rats were given clomiphene citrate at dose 100ug/kg orally. Results: Significant weight gain is observed in rats taking clomiphene citrate as compared to letrozole Conclusion : Comiphene citrate directly affects the body weight which indirectly reduces the ovulation induction and pregnancy rate. Letrozole is good alternate for ovulation induction and for CC resistant patients. Keywords: Estrous cycle, body weight, citrate and letrozole

Prolactin receptor regulates the seasonal reproduction of striped hamsters

Zygote ◽  
2021 ◽  
pp. 1-8
Author(s):  
Huiliang Xue ◽  
Jinhui Xu ◽  
Ming Wu ◽  
Lei Chen ◽  
Laixiang Xu
Keyword(s):  
Prolactin Receptor ◽  
Expression Patterns ◽  
Reproductive Activity ◽  
Mature Female ◽  
Seasonal Reproduction ◽  
Population Abundance ◽  
Serum Concentrations ◽  
Expression Levels ◽  
Autumn And Winter ◽  
Differential Mrna Expression

Summary In this study, differential mRNA expression patterns of prolactin receptor (PRLR) in the hypothalamus and gonads, and the correlation with follicle stimulating hormone (FSH) and luteinizing hormone (LH) in striped hamster serum from spring, summer, autumn and winter were analyzed. Mature female and male striped hamsters in oestrus were used. Expression levels of PRLR in the hypothalamus, ovaries and testis from the summer and winter individuals were significantly higher compared with levels from the spring and autumn, whereas FSH and LH serum concentrations from summer and winter individuals were significantly lower compared with that from the spring and autumn. PRLR expression levels in hypothalamus, ovaries and testis were negatively correlated with FSH and LH serum concentrations, illustrating that PRLR might negatively regulate seasonal reproductive activity. PRLR expression levels in ovaries and testes were significantly higher compared with levels in the hypothalamus, suggesting that the regulative effects of PRLR in gonads might be significantly higher compared with that in the hypothalamus. Furthermore, PRLR expression levels from the spring, summer, autumn and winter seasons in the hypothalamus and gonads were significantly higher in females compared with levels in males, indicating that the regulative effect of PRLR might be sex dependent. Taken together, this study helps to understand in depth the seasonal regulative reproduction mechanism of striped hamsters to reasonably control population abundance.

Studies on Ovarian Follicular Dynamics and Steroid Profiles in Sahiwal Cattle

2021 ◽  
Author(s):  
Vinny Dodiyar ◽  
Parkash Singh Brar ◽  
Narinder Singh ◽  
Mrigank Honparkhe
Keyword(s):  
Corpus Luteum ◽  
Estrous Cycle ◽  
Maximum Diameter ◽  
Endocrine Regulation ◽  
Dominant Follicle ◽  
Estrous Cycles ◽  
Significant Difference ◽  
Sahiwal Cattle ◽  
Sahiwal Cows ◽  
Follicular Dynamics

Background: Understanding of ovarian follicular dynamics and endocrine regulation is essential to design and use interventions to optimize reproductive efficiency. Bos indicus and Bos taurus cows have some differences in their follicular dynamics and ovarian steroidal hormones. The present study was planned to understand follicular dynamics vis-a-vis ovarian steroids profiles in Sahiwal cattle. Methods: The study was conducted in normal cyclic, pluriparous, non-lactating Sahiwal cows (n=7). Trans-rectal ultrasonography was performed to record the location, size, number of follicles and size of corpus luteum (CL) from the beginning, till the end of experiment. The dataset was used to characterize the follicular wave emergence, growth, regression, time of selection and ovulation of the dominant follicle in each cow. Result: Three Sahiwal cows showed two wave and four cows showed three wave estrous cycles with mean interovulatory length of 20.33±0.33 and 22.50±0.28 days, respectively. No significant difference was recorded in the maximum diameter of corpus luteum, P4 and E2 plasma levels between 2-wave and 3-wave estrous cycles. The peak progesterone values of 6.00±0.91 and 6.2±1.2 ng/ml and peak estradiol values of 15.83±0.60 and 14.31±0.44 ng/ml were recorded in 2-wave and 3-wave estrous cycle, respectively. The results showed that Sahiwal cows had 2-wave and 3-wave estrous cycle and the 3-wave estrous cycle had comparatively longer inter-ovulatory period and smaller maximum diameter of second wave dominant follicle than 2-wave estrous cycle.

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