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 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.

The effect of melatonin treatment during the seasonal anoestrus on the superovulatory response and embryo production of high-prolificacy Rasa Aragonesa ewes before culling

2003 ◽  
Vol 2003 ◽  
pp. 82-82
Author(s):  
F. Forcada ◽  
J.A. Abecia ◽  
J.A. Valares
Keyword(s):  
Embryonic Development ◽  
Breeding Season ◽  
Litter Size ◽  
Direct Effect ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Melatonin Treatment ◽  
Embryo Production ◽  
Spring Equinox

The efficacy of melatonin implants inserted around the spring equinox to improve fertility and ovulation rate or litter size in Mediterranean ewes has been previously reported (Chemineau et al., 1996; Forcada et al., 2002a.), indicating the ability of the hormone to regulate the hypothalamic activity (Viguié et al., 1995). Moreover, a direct effect of melatonin on corpora lutea and embryonic development has been also reported (Wallace et al., 1988; Abecia et al., 2002). The use of prolific Rasa Aragonesa (RA) ewes (a Mediterranean breed) before culling as embryo donors has been previously tested in the breeding season (Forcada et al., 2002b.). The aim of this experiment was to improve embryo production during the seasonal anoestrus period in selected superovulated RA ewes at the end of their reproductive lives through the use of melatonin.

407 SUPERSTIMULATORY RESPONSE WITH DECREASING DOSES OF FOLLICLE-STIMULATING HORMONE v. A SINGLE DOSE OF FOLLICLE-STIMULATING HORMONE - EQUINE CHORIONIC GONADOTROPIN DURING BREEDING AND NONBREEDING SEASON IN SHEEP

2010 ◽  
Vol 22 (1) ◽  
pp. 360
Author(s):  
M. I. Cueto ◽  
F. Pereyra-Bonnet ◽  
P. Silvestre ◽  
A. E. Gibbons
Keyword(s):  
Single Dose ◽  
Breeding Season ◽  
Recovery Rate ◽  
Follicle Stimulating Hormone ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Nonbreeding Season ◽  
Embryo Recovery ◽  
The One ◽  
Stimulating Hormone

The aim of the study was to assess possible variations in superovulatory yields due to different FSH treatments at 2 times of the year. Superovulation and embryo recovery were performed during the breeding (n = 63) andnonbreeding (n = 46) seasons in Merino ewes located at 41°S latitude. Animals were kept under the same conditions, housed outdoors in a sheltered and covered pen, and were fed a liveweight maintenance ration. All animals received 60-mg medroxyprogesterone acetate intravaginal sponges (Progespon®, Syntex, Buenos Aires, Argentina) for 14 days. Ewes were then randomly assigned to 2 different superovulatory treatments: classic (n = 74) and one shot (n = 35) in both seasons. Classic superovulatory treatment consisted of 7 decreasing doses (2 × 48 mg, 2 × 24 mg, 2 × 20 mg, and1 × 16 mg NIH-FSH-P1)ofFSH (Folltropin®-V, Bioniche, Belleville, Ontario, Canada), administered twice daily from 48 h before to 24 h after pessary removal. A dose of eCG (300 IU; Novormon®, Syntex) was administered at progestagen removal. One shot superovulatory treatment consisted of a single dose of FSH (70 mg NIH-FSH-P1) plus 300 UI of eCG injected at pessary withdrawal. Embryo donors were inseminated by laparoscopy with frozen-thawed semen (100 × 106 spz) 12 h after the onset of estrus. Surgical embryo recovery was done on Day 7 after sponge withdrawal and embryos were graded for quality according to morphology (Grade 1 = excellent or good; Grade 2 = fair; Grade 3 = poor; and Grade 4 = dead or degenerated; IETS 1998). A 2 × 2 factorial ANOVA was used to test the main effects (season and superovulatory treatment) and interactions. There were no significant differences in the proportion of responding ewes (>3 corpora lutea), ovulation rate, and recovered Grades 1 to 2 embryos between the breeding and nonbreeding season (Table 1; P > 0.05). However, number of recovered ova/embryos and ova/embryo recovery rate were higher during the breeding season compared with the nonbreeding season, whereas the percentage of nonfertilized ova was lower in the breeding season than in the nonbreeding season (P < 0.05). Analysis of data comparing superovulatory treatments showed that the proportion of responding ewes, ovulation rate, recovered embryos, and recovered Grades 1 to 2 embryos were lower for the one shot treatment than for the classic treatment (P < 0.05). Embryo recovery rate and nonfertilization rate did not differ between treatments (P > 0.05). It was concluded that there was an increase in the number of total recovered ova/embryos during the breeding season compared with the nonbreeding season, although the number of recovered good-quality embryos was not affected. The use of multiple FSH injections produced a higher number of total recovered and viable embryos in Merino sheep than the one shot superovulatory treatment. Table 1.Embryo yields in ewes submitted to superovulation

The effect of exogenous melatonin and the plane of nutrition after weaning on ovulation rate in salz ewes lambing in the seasonal anoestrus

1994 ◽  
Vol 1994 ◽  
pp. 83-83
Author(s):  
L. Zarazaga ◽  
F. Forcada ◽  
J.A. Abecia ◽  
J. Mozota
Keyword(s):  
Nutritional Status ◽  
Sexual Activity ◽  
Breeding Season ◽  
Nutrient Status ◽  
Ovulation Rate ◽  
The Other ◽  
Cyclic Activity ◽  
Exogenous Melatonin ◽  
Short Period ◽  
Ovarian Cyclicity

Induction of oestrus and pregnancy in the seasonal anoestrus permits lambing during the breeding season and mating in a short period of time after weaning, but after spring lambing postpartum anoestrus is longer than it is in autumn lambing, and no breeds are able to resume cyclic activity two months after lambing. Nutrient status has been shown to be a major factor affecting the onset of ovarian cyclicity in postpartum ewes. On the other hand, melatonin implants were demonstrated to be efficient in advancing the annual breeding season, but the efficiency of this treatment could be modified by the nutritional status of the animals. The aim of this experiment was to determine the effect of exogenous melatonin, connected with the plane of nutrition after weaning, on the resumption of sexual activity and ovulation rate (OR) in a synthetic Spanish sheep breed lambing in spring.

THE BREEDING SEASON AND OVULATION RATE OF DLS EWES AS DETERMINED BY LAPAROSCOPY

1986 ◽  
Vol 66 (1) ◽  
pp. 297-301 ◽  
Author(s):  
MOHAMED H. FAHMY ◽  
JACQUES J. DUFOUR
Keyword(s):  
Key Words ◽  
Breeding Season ◽  
Ovulation Rate ◽  
Corpora Lutea

Ovaries of 19 DLS (1/2 Dorset 1/4 Leicester 1/4 Suffolk) ewes were examined by laparoscopy at 16- to 18-day intervals to determine the length of the breeding season. Nine ewes (47%) had corpora lutea (CL) and/or corpora albicantia (CA) between 22 Apr. and 26 May 1983. The average date of the first estrus accompanied by mounting was 28 Aug. ± 10 d in 1983 and 20 Sept. ± 15 d in 1984. The interval between first and last observed CL and first and last mounting averaged 251 ± 28, and 222 ± 32 d, respectively. The average dates in 1984 when mounting ceased and CL and CA were last observed were 11 Apr. ± 26 d, 26 Apr. ± 27 d and 9 May ± 30 d, respectively. The anestrous period averaged 133 ± 28 d. The average ovulation rate at the last two cycles of a season and the first two cycles of the following breeding season were 1.6 ± 0.53 and 1.7 ± 0.65 for the 1983 and 1.1 ± 0.31 and 1.4 ± 0.71 for the 1984 seasons, respectively. Key words: Breeding season, ovulation rate, laparoscopy, DLS sheep

Effect of melatonin on the peripheral concentrations of LH and progesterone after oestrus, and on conception rate in ewes

1988 ◽  
Vol 119 (3) ◽  
pp. 523-530 ◽  
Author(s):  
J. M. Wallace ◽  
J. J. Robinson ◽  
S. Wigzell ◽  
R. P. Aitken
Keyword(s):  
Breeding Season ◽  
Pulse Generator ◽  
Ovulation Rate ◽  
Melatonin Treatment ◽  
Embryo Survival ◽  
Plasma Progesterone ◽  
Progesterone Secretion ◽  
Endocrine Status ◽  
Increased Activity ◽  
Intra Uterine Insemination

ABSTRACT It has previously been shown that administration of the indoleamine melatonin to advance the breeding season of ewes is also associated with an increase in ovulation rate and subsequent litter size. Experiment 1 assessed whether, in ewes receiving melatonin to advance the breeding season, the indoleamine acts directly on the corpus luteum to enhance progesterone secretion or indirectly through increased activity of the hypothalamic pulse generator. Six ewes received 3 mg melatonin orally at 15.00 h daily from 22 March onwards, six were induced to ovulate during mid-anoestrus following withdrawal of a progestagen pessary and injection of exogenous gonadotrophin and six acted as naturally ovulating controls. First overt oestrus occurred between 17 May and 8 July in melatonin-treated ewes, between 21 October and 3 January in control ewes and on 8 July in all induced ewes. On days 2 and 10 after the first overt oestrus, melatonin-treated ewes had pulsatile LH activity characteristic of that measured in control ewes ovulating naturally during the breeding season. There was an absence of any pulsatile LH activity in the induced ewes. Progesterone concentrations between days 7 and 12 following oestrus were significantly higher in melatonin-treated than in control and induced ewes, suggesting a luteotrophic role for melatonin. Experiment 2 was carried out to determine whether administration of melatonin commencing after induced ovulation and insemination would alter the endocrine status of the ewe and thereby influence the establishment of pregnancy and embryo survival. Thirty-two anoestrous ewes were induced to ovulate on 29 June. Starting 24 h after intra-uterine insemination, 16 ewes were given melatonin daily for 60 days and 16 acted as controls. Daily LH concentrations were higher in melatonin-treated than in control ewes from days 2 to 22 after oestrus, while prolactin concentrations declined in melatonin-treated ewes over the same period. Plasma progesterone concentrations were enhanced in melatonin-treated ewes between days 4 and 9 following oestrus, yet ovulation rates were the same as for controls. Successful pregnancies occurred in 0·56 control (9 of 16) and 0·69 melatonin-treated (11 of 16) ewes. For these ewes the number of fetuses surviving to term as a proportion of ovulation rate was 0·43 and 0·51 for the control and melatonin treatment respectively. J. Endocr. (1988) 119, 523–530

Pre- and peri-pubertal feed intake: effects on age at puberty and potential litter size of replacement gilts

2017 ◽  
Vol 57 (6) ◽  
pp. 1040
Author(s):  
W. H. E. J. van Wettere ◽  
M. Mitchell ◽  
D. K. Revell ◽  
P. E. Hughes
Keyword(s):  
Litter Size ◽  
Dietary Restriction ◽  
Feed Intake ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Short Term ◽  
Large White ◽  
Embryo Number ◽  
Age At Puberty

The effect of moderate restriction of pre- and peri-pubertal liveweight gain on puberty attainment and potential litter size was investigated. At 69 days of age, 48 Large White/Landrace crossbred gilts (28.3 ± 0.3 kg), were fed to attain a liveweight of 70 kg (LIGHT) or 100 kg (HEAVY) at 161 days of age (n = 24 gilts/treatment). At 161 days of age, half the gilts in each group were fed to gain liveweight at 0.5 (LOW) or 1.0 (HIGH) kg/day until puberty (n = 12 gilts/treatment). From 175 days of age, gilts received 20 min/day of full, physical boar contact. Gilts were artificially inseminated at the pubertal oestrus, with reproductive tracts collected 22 ± 0.1 days later, and the number of corpora lutea and viable embryos recorded. LIGHT-LOW gilts were older (P < 0.05) at puberty compared with LIGHT-HIGH, HEAVY-LOW and HEAVY-HIGH gilts; 207.7 ± 3.50 versus 191.7 ± 3.65, 193.1 ± 3.50 and 192.5 ± 3.65, respectively. Treatment (HIGH vs LOW) increased (P < 0.05) pubertal ovulation rate (15.2 ± 0.43 vs 13.1 ± 0.47), oestradiol at oestrus (13.4 ± 1.87 vs 9.1 ± 1.22 pg/mL) and progesterone 72 h post-oestrus (7.1 ± 0.48 vs 4.6 ± 0.50 ng/mL). Embryo number (10.8 ± 0.46) and survival (77.0 ± 3.21) were unaffected (P > 0.05) by treatment. To conclude, puberty was delayed by chronic, but not acute, dietary restriction. Although short-term, moderate increases in feed intake increased pubertal ovulation rates, embryo numbers and survival were unaffected.

Comparison of luteal function between ewe lambs and ewes during breeding and non breeding season

1998 ◽  
Vol 1998 ◽  
pp. 184-184
Author(s):  
T.H. Khan ◽  
N.F.G. Beck ◽  
M. Khalid
Keyword(s):  
Embryo Development ◽  
Breeding Season ◽  
Reproductive Performance ◽  
Corpora Lutea ◽  
Luteal Function ◽  
Previous Evidence ◽  
Ewe Lambs

Reproductive performance of ewe lambs is lower than that of adult ewes (Quirke. 1979). This is mainly the result of preimplantation losses which can exceed 50% in ewe lambs as compared with 20-30% in ewes (Quirke et al.,1981). Previous evidence from this laboratory suggests that these losses may be associated with inadequate luteal function in ewe lambs (Davies and Beck, 1993). Inadequate luteal function may not only delay the embryo development but also impair the ability of the embryo to communicate its presence to the maternal system. There is also a possibility that inadequate corpora lutea may be refractory to luteotrophic factors produced by the developing embryo. The present study was designed to investigate whether the luteal function varies between ewe lambs and ewes. Another objective of this study was to compare the luteal response to hCG challenge between ewe lambs and ewes and its variation with season.

Annual reproductive rhythm and ovulation rate in four fat-tailed sheep breeds

1978 ◽  
Vol 26 (2) ◽  
pp. 177-184 ◽  
Author(s):  
N. Sefidbakht ◽  
M. S. Mostafavi ◽  
A. Farid
Keyword(s):  
Sexual Activity ◽  
Seasonal Pattern ◽  
Recovery Phase ◽  
Significant Decline ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Sexually Active ◽  
Monthly Variation ◽  
The Mean ◽  
Mean Cycle

ABSTRACTKarakul, Mehraban, Naeini and Bakhtiari sheep were checked twice a day for oestrus using aproned rams and were laparotomized within 5 to 16 h of the end of every second oestrous period. Oestrus was observed for 12 monthly periods commencing on 21 April.The Mehraban breed with 1 -6 oestrous periods per month was less seasonal in its breeding activity (P<0·01) than the other breeds. Four-year-old ewes were more sexually active (P<0·01) than 3-year-old ewes (1·48 v. 1·28 oestrous periods per month). Seasonal variation in the sexual activity of the ewes was observed (P<001); the peak of activity in July to January was followed by a steady decline in February and March to a low in April and May, and then a steep recovery phase in June. There was only limited sexual activity for at least 4 months (March to June).The overall mean cycle length was 17·8 days (14 to 23 days), and the means for the four breeds were 17·6, 17·8, 17·8 and 17·9. The oestrous cycle was longer (P<0·05) during the period from December t o February than during that from June to August.The overall mean duration of the oestrous period was 36·9 h and the means for the four breeds were 35·2, 38·0, 37·4 and 37·1 h, respectively (P<0·05). The duration showed some monthly variation (P<0·01) but did not follow a special seasonal pattern. The ovulation rates for the four breeds were 1·07, 1·13,0·94 and 0·95 respectively, (P<0·01). There was a non-significant decline in the mean ovulation rate from March to June. Right ovaries were more active than left ovaries as judged by the observation of a higher average number of corpora lutea per ewe per laparotomy (0·58 v. 0·43, P<001).

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