Effect of ram introduction upon the pulsatile release of LH and follicle development in pre-puberal ewe lambs

The introduction of rams to seasonally-anovular ewes will, at certain times of the year, stimulate increased pulsatile release of LH, follicle development and ovulation (Martin et al., 1986). The neuroendocrine mechanism governing the transition into adulthood of ewe lambs is incompletely understood, but it is believed to be similar to that which controls the transition to the breeding season in the adult ewe (Foster, Yellon and Olster, 1985; Legan, Karsch and Foster, 1977). Thus the introduction of rams may have a similar action in the pre-puberal ewe lamb as in the seasonally-anovular adult ewe. This experiment investigated the effect of the introduction of rams on the pattern of LH secretion and follicle development in ewe lambs during the late summer/early autumn of their first year of life.

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Studies on the breeding season of Icelandic ewes and ewe lambs

The Journal of Agricultural Science ◽

10.1017/s0021859600055350 ◽

1978 ◽

Vol 90 (2) ◽

pp. 275-281 ◽

Cited By ~ 18

Author(s):

Ø. R. Dýrmundsson

Keyword(s):

Breeding Season ◽

Individual Variation ◽

First Year ◽

Cyclic Activity ◽

Breeding Activity ◽

Ewe Lambs ◽

The Mean ◽

Considerable Individual Variation ◽

A Minor ◽

First Year Of Life

SummaryThe paper reports on a study, conducted in four successive seasons, of sexual development and breeding activity in females of the Iceland breed, the only breed of sheep kept in the country. The ewe lambs normally attained puberty in their first year of life, on average at 7 months of age, with marked individual variation in both age and body weight at first oestrus. Ewe lambs always showed oestrus on average slightly later than mature ewes (2–9 years), the mean date of onset of the breeding season of the latter being 8 December, however, with considerable individual variation. Furthermore, ewe lambs had a shorter breeding season (1–4 months) than ewes (4–6 months) and they appeared to experience more silent heats resulting in less regular cyclic activity. There seemed to be a minor increase in the duration of the oestrous cycle with age and ewe lambs clearly exhibited shorter oestrus (heat) than ewes. With seasonal breeding activity ranging from November to May the mid-breeding season occurs some 4–7 weeks after the shortest day.

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Improving production from September-born Merino lambs with a lupin grain supplement and phomopsis-resistant lupin stubbles

Australian Journal of Experimental Agriculture ◽

10.1071/ea9930713 ◽

1993 ◽

Vol 33 (6) ◽

pp. 713 ◽

Cited By ~ 2

Author(s):

PW Morcombe ◽

JG Allen

Keyword(s):

Weight Loss ◽

Liver Injury ◽

Western Australia ◽

First Year ◽

Ewe Lamb ◽

Grazing Sheep ◽

Staple Strength ◽

Good Productivity ◽

First Year Of Life ◽

The Cost

As a means of providing nutrition on dry pasture in the wheatbelt of Western Australia, supplements of lupin grain were fed to late-born Merino lambs and their dams before weaning onto lupin stubble. Each ewe-lamb pair consumed an average 19.5 kg lupin grain over the 46 days before weaning. This produced an extra 3.6 kg (P<0.01) liveweight gain by these lambs compared with their unsupplemented cohorts at weaning. The growth of the weaned lambs grazing phomopsis-resistant lupin stubbles was primarily influenced by the amount of residual lupin grain available to each sheep and liver injury caused by ingestion of phomopsins. In the first 69 days of stubble grazing, sheep stocked at 10ha gained 7.3 kg while those stocked at 20ka gained 2.1 kg (P<0.001). In the first 13 months of life, lambs supplemented with lupin grain before weaning grew more (P<0.05) clean wool by 0.17 kg than the unsupplemented lambs. However, the value of this extra wool would not have covered the cost of the lupin grain eaten. Wool staples produced by sheep grazed at 10/ha on lupin stubble were stronger (P<0.001) than those produced by sheep grazed at 20ha (24.4 v. 17.7 N/ktex). The position of greatest weakness in the staple coincided with weight loss prior to removal from the stubble. Singleton lambs born in September and weaned onto a phomopsis-resistant lupin stubble reached liveweights consistent with survival over the summer and good productivity in their first year of life. The effects of lupinosis and reductions in wool staple strength may have been avoided by monitoring liveweight change and taking the sheep off the stubbles when they were near peak liveweight.

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Effect of the introduction of rams on the pulsatile release of luteinizing hormone and the onset of reproductive activity in ewe lambs

Animal Science ◽

10.1017/s0003356100020146 ◽

1991 ◽

Vol 53 (2) ◽

pp. 209-214 ◽

Cited By ~ 15

Author(s):

N. Z. N. Al-Mauly ◽

M. J. Bryant ◽

F. J. Cunningham

Keyword(s):

Luteinizing Hormone ◽

Sampling Period ◽

Reproductive Activity ◽

Pulse Frequency ◽

Pulsatile Release ◽

Ewe Lambs ◽

The Mean ◽

First Time ◽

Lh Secretion

AbstractPre-pubertal ewe lambs were introduced to rams on 17 August (Tl), 12 September (T2) or 10 October (T3) or isolated from rams until 21 December (Tc) (no. = 13). Blood was taken for progesterone assay three times weekly (no. = 13) from 16 July. Blood was taken for LH assay at 15-min intervals for 8 h (no. = 8) at the time of the introduction of rams and subsequently at the time of further ram introductions. Blood was taken from Tc lambs at each ram introduction. Tl, T2 and T3 lambs ovulated for the first time 16 (s.e. 2·2) days earlier than Tc lambs but only T3 lambs ovulated after and apparently in response to the introduction of the rams. The mean baseline LH levels were higher in Tl, T2 and T3 lambs in comparison with Tc lambs at all sampling periods. The mean pulse frequency of LH secretion was significantly increased by the introduction of rams in T2 and T3 lambs in comparison with Tc lambs. The mean pulse frequency of LH secretion was greater in Tl, T2 and T3 lambs at the October sampling period in comparison to Tc lambs.

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140 Endocrine Profiling in Prepubertal Stallions with Abnormal Testicular Development

Reproduction Fertility and Development ◽

10.1071/rdv30n1ab140 ◽

2018 ◽

Vol 30 (1) ◽

pp. 210

Author(s):

D. Scarlet ◽

J. Kuhl ◽

M. Wulf ◽

N. Ille ◽

M. Köhne ◽

...

Keyword(s):

Repeated Measures ◽

Early Stage ◽

Significant Negative Correlation ◽

Perinatal Period ◽

Testicular Volume ◽

First Year ◽

Testicular Development ◽

Testicular Morphology ◽

First Year Of Life ◽

Lh Secretion

The use of anti-Müllerian hormone (AMH) as a biomarker for assessment of male gonadal activity has become increasingly widespread. Aberrant AMH concentration successfully detects cryptorchids or pathologic testes in postpubertal stallions, but the ability to use AMH to identify stallions with testicular pathologies during their prepubertal life has not been analysed so far. The objectives of this work were to (1) assess AMH, testosterone, LH, and FSH dynamics in male horses with or without testicular pathologies during the first year of life; and (2) find a reliable diagnostic approach that would enable the identification of animals that will develop abnormal testes at an early stage. Warmblood colts (n = 16) born from February to May on the same stud farm were used. Blood samples for hormone determinations were collected from birth onwards every 4 weeks until the age of 1 year. At 2 years, testicular development was assessed, total testicular volume calculated. and a blood sample collected. Concentrations of AMH, testosterone, LH, and FSH were determined in all samples; AMH (AL-115, Ansh Laboratories, Webster, TX, USA) and testosterone (DE1559, Demeditec, Kiel-Wellsee, Germany) concentrations were determined by ELISA, whereas LH and FSH concentrations were determined by radioimmunoassay. Statistical analysis (SPSS Statistics 24; IBM/SPSS, Armonk, NY, USA) was performed by ANOVA using a general linear model for repeated measures. In 2 stallions, unilateral cryptorchism, and in other 4 stallions, subnormal total testicular volume (<mean minus SD) were diagnosed at 2 years. Concentrations of AMH, testosterone, and FSH changed over time (P < 0.001) but were similar (P > 0.05) within the first year of life irrespective of testicular morphology and location. Concentration of LH at birth was lower (P = 0.05) in stallions with abnormal testes (0.3 ± 0.2 ng mL−1) than in controls (0.6 ± 0.2 ng mL−1), but did not differ thereafter. At 2 years of age, AMH concentration was higher (P < 0.01) in stallions with abnormal testes (39.7 ± 12.7 ng mL−1) than in controls (8.0 ± 0.2 ng mL−1), but no group differences with regard to LH, FSH, and testosterone existed. There was a low but significant negative correlation between AMH and FSH (P < 0.001, r = –0.24), as well as between AMH and LH (P < 0.05, r = –0.15). Also, testosterone concentration was positively correlated with FSH (P < 0.05, r = 0.18) and LH (P < 0.05, r = 0.16) concentrations. In conclusion, AMH determination can be reliably used from 2 years onwards to identify stallions with abnormal testicular development, but it is inconclusive before puberty. We concluded that LH secretion in the perinatal period is involved in testicular development and descent in the horse.

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Does dam parity affect the performance of ewe progeny born to 2-year-old ewes?

Australian Journal of Experimental Agriculture ◽

10.1071/ea07392 ◽

2008 ◽

Vol 48 (7) ◽

pp. 979 ◽

Cited By ~ 4

Author(s):

P. R. Kenyon ◽

S. T. Morris ◽

H. T. Blair ◽

K. J. Stafford

Keyword(s):

Production Systems ◽

First Year ◽

Productive Performance ◽

Breeding Performance ◽

Female Progeny ◽

Ewe Lambs ◽

Birth Rank ◽

Condition Score ◽

Ewe Lamb ◽

Puberty Onset

An increasing number of ewe lambs are being presented for breeding in New Zealand, resulting in more two-tooth ewes of second parity compared with the more normal first parity. The effect of this on the resulting ewe progeny is unknown but is of interest as they are potential replacement ewes. This study was designed to determine if parity of Romney two-tooth ewes had any effect on their ewe lamb progeny to 20 months of age. Two-hundred and fifty female progeny born to two-tooth dams, which had lambed as a ewe lamb (n = 97), failed to conceive at ewe lamb breeding (n = 79), or had not been presented for breeding as a ewe lamb (n = 74), were weighed at regular intervals. The progeny also had onset of puberty and two-tooth breeding and pregnancy scanning performance measured. There were no effects of dam group on liveweight, condition score, 18-month breeding performance or pregnancy diagnosis. However, ewe lambs born to dams which failed to conceive as ewe lambs themselves were less likely (P < 0.05) to achieve puberty. In comparison with single-born lambs, twin-born ewes were lighter (P < 0.05) during their first year of age only. Birth rank had no effect on puberty onset or 18-month breeding performance. These findings indicate that ewe progeny born to second parity two-tooths or two-tooths, which were not presented for breeding as a ewe lamb, do not differ in their productive performance and that either group are suitable as replacement ewes. However, progeny born to two-tooth dams, which failed to conceive as a ewe lamb, would be less suitable as replacement ewes in production systems where ewe lamb breeding is an integral component of the system. Further studies are required to determine if similar relationships would be observed under differing environmental conditions and with different breeds.

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Pituitary and plasma levels of growth hormone in Booroola sheep that are either homozygous carriers or non-carriers of the FecBB fecundity gene

Journal of Endocrinology ◽

10.1677/joe.0.1470217 ◽

1995 ◽

Vol 147 (2) ◽

pp. 217-223

Author(s):

L G Moore ◽

K P McNatty ◽

K L Isaacs ◽

S Lun ◽

W Ng Chie ◽

...

Keyword(s):

Growth Hormone ◽

Body Weight ◽

Plasma Concentrations ◽

First Year ◽

Lower Body ◽

Ewe Lambs ◽

Body Weights ◽

Ram Lambs ◽

Plasma Gh ◽

First Year Of Life

Abstract The aim of this study was to examine the effect of the FecBB fecundity gene on plasma concentrations and pituitary content of growth hormone (GH) in sheep. No differences were found between homozygous carriers (BB) and non carriers (++) of the FecBB gene with regard to pituitary GH contents in both ovariectomized and intact ewes. However, ovariectomized ewes had higher levels of pituitary GH than intact ewes (P<0·01). There were no differences between FecBB genotypes with respect to plasma concentrations of GH in 6-year-old ovariectomized ewes bled every 10 min for 12 h or in ram lambs bled weekly during their first year of life. GH levels in the rams decreased until week 27, increased to a peak at week 31 then decreased before increasing again at week 43. Mean plasma GH concentrations in the ewe lambs bled weekly for a year decreased until week 19 then remained at approximately this level for the remainder of the year. Mean GH plasma concentrations in the ram lambs were higher than in the ewe lambs (P<0·001). Ewe lambs that were homozygous for the FecBB gene had lower body weights (P<0·05) and had higher levels of GH (P<0·01) than non carrier ewe lambs during their first year. Before the average age of first behavioural oestrus (36 weeks) GH levels in the ewe lambs were negatively correlated with body weights (r=−0·69, P<0·001, n=22). When body weight was included as a covariate in analysis of variance the genotype difference in ewe lamb plasma GH concentrations was no longer significant. In summary, pituitaries from ovariectomized ewes had higher levels of GH than those from intact ewes. There were no FecBB gene specific differences in pituitary levels of GH, the profile of plasma GH in 6-year-old ovariectomized ewes or in ram lambs during their first year of life. BB ewe lambs had higher levels of GH than ++ ewe lambs during their first year; however, this difference was probably due to the BB ewes having lower body weights than the ++ ewes because body weight was negatively correlated with mean GH levels. Journal of Endocrinology (1995) 147, 217–223

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A new perspective on managing the onset of puberty and early reproductive performance in ewe lambs: a review

Animal Production Science ◽

10.1071/an17787 ◽

2018 ◽

Vol 58 (11) ◽

pp. 1967 ◽

Cited By ~ 1

Author(s):

C. A. Rosales Nieto ◽

A. N. Thompson ◽

G. B. Martin

Keyword(s):

Reproductive Performance ◽

Meat Production ◽

First Year ◽

Global Changes ◽

Early Puberty ◽

Major Step ◽

Ewe Lambs ◽

New Perspective ◽

First Year Of Life ◽

The Brain

Global changes in industry and society have led us to reassess the numerous factors that combine to influence the time of onset of puberty and the efficiency of reproduction in young sheep. Age and weight have long been considered the dominant factors that influence the onset of puberty and, for many years, it has been accepted that these relationships are mediated by the hormone, leptin, produced by body fat. However, recent studies showing that muscle mass also plays a role have challenged this dogma and also presented new options for our understanding of metabolic inputs into the brain control of reproduction. Moreover, the possibility that an improvement in meat production will simultaneously advance puberty is exciting from an industry perspective. An industry goal of strong reproductive performance in the first year of life is becoming possible and, with it, a major step upwards in the lifetime reproductive performance of ewes. The concept of early puberty is not well accepted by producers for a variety of reasons, but the new data show clear industry benefits, so the next challenge is to change that perception and encourage producers to manage young ewes so they produce their first lamb at 1 year of age.

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Use of a tropical bay in southeastern Brazil by juvenile and subadult Micropogonias furnieri (Perciformes, Sciaenidae)

ICES Journal of Marine Science ◽

10.1016/s1054-3139(02)00272-2 ◽

2003 ◽

Vol 60 (2) ◽

pp. 268-277 ◽

Cited By ~ 16

Author(s):

Marcus R da Costa ◽

Francisco G Araújo

Keyword(s):

Late Summer ◽

Coastal Areas ◽

Southeastern Brazil ◽

Otter Trawl ◽

First Year ◽

White Croaker ◽

Micropogonias Furnieri ◽

New Recruits ◽

First Year Of Life ◽

Spatial Usage

Abstract The white croaker Micropogonias furnieri is a commercially important marine fish that uses bays and other semi-closed coastal areas early in its life. A sampling programme, using beach-seine and otter trawl, was carried out in Sepetiba Bay (22°54′–23°04′S, 43°34′–44°10′W), southern Brazil, from October 1998 to September 1999, with the objective of assessing the patterns of temporal and spatial usage of the bay by white croaker during its early life. Early recruits (total length, TL, 10–50 mm) appear off beaches of the inner bay between October and December, move away from them during late summer and early autumn (January–April), and are caught by trawl offshore from May to September at a TL of 70–150 mm. From May to August, new recruits (10–50 mm) are again found inshore. Fish grow from 10–40 to 70–150 mm during the first year of life in the shallows of the bay, before moving offshore. They cross the deeper waters of the bay as they migrate towards the open ocean. Juveniles (TL 70–150 mm) are most abundant in the inner bay, and subadults (TL 150–200 mm) in the outer and central bay. M. furnieri use semi-closed coastal areas as nursery grounds, before moving out over the continental shelf, where they spawn.

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The Development of Swallowing Respiratory Coordination

Perspectives on Swallowing and Swallowing Disorders (Dysphagia) ◽

10.1044/sasd18.1.19 ◽

2009 ◽

Vol 18 (1) ◽

pp. 19-24

Author(s):

Maggie-Lee Huckabee

Keyword(s):

Cortical Activation ◽

First Year ◽

Healthy Children ◽

Nasal Airflow ◽

Single Session ◽

Primary Finding ◽

Patterns Of Behavior ◽

Cortical Modulation ◽

First Year Of Life ◽

Swallowing Apnea

Abstract Research exists that evaluates the mechanics of swallowing respiratory coordination in healthy children and adults as well and individuals with swallowing impairment. The research program summarized in this article represents a systematic examination of swallowing respiratory coordination across the lifespan as a means of behaviorally investigating mechanisms of cortical modulation. Using time-locked recordings of submental surface electromyography, nasal airflow, and thyroid acoustics, three conditions of swallowing were evaluated in 20 adults in a single session and 10 infants in 10 sessions across the first year of life. The three swallowing conditions were selected to represent a continuum of volitional through nonvolitional swallowing control on the basis of a decreasing level of cortical activation. Our primary finding is that, across the lifespan, brainstem control strongly dictates the duration of swallowing apnea and is heavily involved in organizing the integration of swallowing and respiration, even in very early infancy. However, there is evidence that cortical modulation increases across the first 12 months of life to approximate more adult-like patterns of behavior. This modulation influences primarily conditions of volitional swallowing; sleep and naïve swallows appear to not be easily adapted by cortical regulation. Thus, it is attention, not arousal that engages cortical mechanisms.

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