The effect of being housed with adult female flock-mates on the age at puberty of autumn-born ewe-lambs

2021 ◽  
Author(s):  
José-Alfonso Abecia ◽  
Antonio Barrio ◽  
José-Antonio Ruiz
Keyword(s):  
Adult Female ◽  
Ewe Lambs ◽  
Age At Puberty

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).

Effects of shearing and prebreeding ram exposure on days to first mark and pregnancy rate of ewe lambs

1991 ◽  
Vol 71 (3) ◽  
pp. 905-907
Author(s):  
R. A. Kemp ◽  
S. F. Lane ◽  
Y. M. Berger
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Pregnancy Rate ◽  
Ewe Lambs ◽  
Age At Puberty

Crossbred ewe lambs were used to examine effects of shearing and prebreeding ram exposure on age at puberty and pregnancy rate. Shearing did not significantly affect age at puberty or growth rate of ewe lambs. Prebreeding ram exposure and/or shearing did not influence pregnancy rate. Key words: Shearing, ram exposure, pregnancy rate, growth

Age at puberty, fertility and litter size of ewe lambs reared under different photogegimens

1991 ◽  
Vol 36 (3) ◽  
pp. 401-409 ◽  
Author(s):  
L. Ainsworth ◽  
D.P. Heaney ◽  
J.N.B. Shrestha
Keyword(s):  
Litter Size ◽  
Ewe Lambs ◽  
Age At Puberty

The onset of the breeding season in Southdown ewes in subtropical Australia

1966 ◽  
Vol 66 (2) ◽  
pp. 295-296 ◽  
Author(s):  
I. D. Smith
Keyword(s):  
Breeding Season ◽  
Ovarian Activity ◽  
Summer Solstice ◽  
Ewe Lambs ◽  
The Mean ◽  
Age At Puberty ◽  
Annual Means ◽  
Subtropical Australia

Observations on the onset of the breeding season in a flock ofSouthdown ewes in subtropical Australia (latitude 27° S.) indicated that the mean date of onset during the years 1962-65 was 3 March, with annual means ranging from 11 February to 17 March. There was evidence that, under some circumstances, ovarian activity may be initiated before the summer solstice.The onset of the breeding season was later in ewe lambs than in yearling and adult ewes and the mean age at puberty was 239 days.

Genetic evaluation of crossbred lamb production. 5. Age of puberty and lambing performance of yearling crossbred ewes

2007 ◽  
Vol 58 (9) ◽  
pp. 928 ◽  
Author(s):  
N. M. Fogarty ◽  
V. M. Ingham ◽  
A. R. Gilmour ◽  
R. A. Afolayan ◽  
L. J. Cummins ◽  
...  
Keyword(s):  
Litter Size ◽  
Significant Variation ◽  
Site Effect ◽  
Genetic Evaluation ◽  
First Year ◽  
Ewe Lambs ◽  
Average Litter Size ◽  
Reproduction Traits ◽  
Age At Puberty ◽  
Sire Breed

The age and liveweight at puberty were evaluated in 2155 crossbred ewe lambs at 2 sites over 3 years. A separate dataset examined the lambing performance of 1177 crossbred ewe lambs that were joined naturally at ~7 months of age at 2 sites over 3 years and also their lambing performances in the subsequent 2 years. The ewe lambs were the progeny of Merino dams and sires from several breeds including Border Leicester, East Friesian, Finnsheep, Coopworth, White Suffolk, Corriedale, and Booroola Leicester. Overall, 85% of the ewe lambs reached puberty (detected by teasers) in their first autumn at an average age of 248 days and liveweight of 42 kg. There was significant variation in age and weight at puberty (P < 0.01) among the site and year cohorts of ewes. Sire breed was significant for weight (P < 0.01) but not age at puberty. Of the crossbred ewe lambs joined at 7 months of age, 54% lambed with an average litter size of 1.31 and 49% of lambs were weaned from the ewes joined. There was a significant site effect for all reproduction traits (P < 0.01), with the higher performance at one site associated with higher liveweight at joining. Maternal sire breed was significant for all reproduction traits (P < 0.01) and there was considerable variation between sires within sire breeds. Ewes that reared lambs in their first year weaned 12% more lambs per year in their second and third years compared with ewes that failed to lamb or rear any lambs at 1 year of age. The results demonstrate that lamb weaning rates of 90% or more can be achieved from crossbred ewe lambs with optimal genetics and management. The opportunities for improving productivity by joining crossbred ewe lambs and the selection and management considerations required for successful joinings and lambings are reviewed and discussed.

scholarly journals Kisspeptin activates the hypothalamic–adenohypophyseal–gonadal axis in prepubertal ewe lambs

Reproduction ◽  
2011 ◽  
Vol 141 (4) ◽  
pp. 541-548 ◽  
Author(s):  
J S Redmond ◽  
G G Macedo ◽  
I C Velez ◽  
A Caraty ◽  
G L Williams ◽  
...  
Keyword(s):  
Short Duration ◽  
Pubertal Development ◽  
Experimental Period ◽  
Post Treatment ◽  
Saline Control ◽  
Pulsatile Release ◽  
Ewe Lambs ◽  
Initial Rise ◽  
The Mean ◽  
Age At Puberty

The onset of puberty in mammals involves an increase in the pulsatile release of GNRH and LH. The KISS1 gene is essential for pubertal development, and its product, kisspeptin, stimulates the release of LH. The objective of this study was to determine the effects of kisspeptin in the hypothalamic–adenohypophyseal–gonadal axis of prepubertal ewe lambs. Ewe lambs (28 weeks of age) were treated intravenously with saline (control, n=6) or kisspeptin (20 μg kisspeptin; n=6) every hour for 24 h. Kisspeptin stimulated pulse-like release of LH within 15 min following injections, and increased the frequency and amplitude of LH pulses, and mean circulating concentrations of LH and estradiol. A surge-like release of LH was observed in four kisspeptin-treated lambs beginning 17 h after the onset of treatment, and all four lambs had elevated circulating concentrations of progesterone within 5 days post-treatment. However, circulating concentrations of progesterone decreased within 2 days after the initial rise in three of the four ewe lambs, indicating that induced luteal activity was of short duration. The proportion of lambs that were pubertal (defined by circulating concentrations of progesterone above 1 ng/ml for at least 7 days) by 35 weeks of age (8/11) and the mean age at puberty (32±1 weeks) for those reaching puberty within the experimental period did not differ between treatments. Results support a role for kisspeptin in the activation of the hypothalamic–adenohypophyseal axis leading to the onset of puberty in ewe lambs.

Age at puberty and possibility of early breeding in Awassi ewes

1978 ◽  
Vol 90 (2) ◽  
pp. 255-260 ◽  
Author(s):  
A. A. Younis ◽  
I. A. El-Gaboory ◽  
E. A. El-Tawil ◽  
A. S. El-Shobokshy
Keyword(s):  
Correlation Coefficients ◽  
Live Weight ◽  
The Other ◽  
Corpora Lutea ◽  
Simple Correlation ◽  
Nutritional Treatment ◽  
Ewe Lambs ◽  
Age At Puberty ◽  
High Treatment ◽  
Daily Gain

SummarySixty-four weaned Awassi ewe lambs were used in the present study to estimate age at puberty and to investigate whether early breeding from such ewe lambs is possible. After weaning at 4 months old ewe lambs were divided at random into two experimental groups. One group, designated as moderate, was fed to attain 40 kg live weight at 12 months of age, while the other (high) was planned to reach 50 kg at the same age. Fertile rams were run with the ewe lambs at 6 months of age. Twenty ewe lambs, 10 from each treatment, were slaughtered and their ovaries were examined for the presence of corpora lutea and largest follicles.The overall age at first oestrus was found to be 293 days. Ewe lambs of the high nutritional treatment reached puberty earlier than those of the moderate one (274 v. 312 days). Likewise, single-born lambs reached puberty earlier than twin-born ones (273 v. 312 days). Treatment differences explained 16·5% while type of birth explained 16·3% of the total variance in age at first oestrus. Ewe lambs of the high nutritional treatment experienced more heats than those of the moderate one. Simple correlation coefficients between age at first oestrus and date of birth, daily gain and live weight at puberty were 0·21, 0·09 and 0·75, respectively. Results indicated that ovulation may not occur during the first and second oestrus. From 44 ewe lambs only 12, 10 from the moderate and 2 from the high treatment, lambed 13 viable lambs. Reasons for such a low conception rate (27·3%) are discussed.

Age at Puberty in Fall-Born Ewe Lambs

1970 ◽  
Vol 30 (6) ◽  
pp. 974-977 ◽  
Author(s):  
E. L. Wiggins ◽  
W. W. Miller ◽  
H. B. Barker
Keyword(s):  
Ewe Lambs ◽  
Age At Puberty

EFFECTS OF SEASONS ON POSTPARTUM CHARACTERISTICS OF SHEEP BEING SELECTED FOR YEAR-ROUND BREEDING AND ON PUBERTY OF THEIR FEMALE PROGENY

1975 ◽  
Vol 55 (4) ◽  
pp. 487-492 ◽  
Author(s):  
J. J. DUFOUR
Keyword(s):  
Body Weight ◽  
Female Progeny ◽  
Ewe Lambs ◽  
Age At Puberty

Second and third parity crossbred ewes being selected for year-round breeding were used after fall lambing, to study the influence of seasons on postpartum characteristics. The average fall lambing date was 8 November, and weaning occurred 14 days later. The interval between weaning and first estrus was then 18.0 days. Following an average spring lambing date of 14 May and weaning again at 14 days, the postweaning interval to first estrus was 87.1 days. Of the ewes bred, 76.6% lambed after fall lambing, 12.7% less than after spring lambing (P < 0.05). Ewes at their second parity needed 0.38 more services (P < 0.05) to produce 0.23 fewer lambs (P < 0.05) than ewes at their third parity. The ewe-lambs born to the ewes lambing in the fall and in the spring were raised to study the influence of seasons of birth on puberty. The percentage reaching puberty and the average age at puberty for ewe-lambs born in the fall were 93.3% and 312.8 days, and those in the spring were 57.1% and 201.8 days. Spring-born ewe-lambs reached puberty 75 days later in the year than fall-born ewe-lambs (P < 0.01). Of the spring-born ewe-lambs, those showing puberty were significantly heavier at 140, 168 and 196 days of age than those not showing puberty, while for the fall-born ewe-lambs, no relationship could be observed between attainment of puberty and body weight.

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