Seasonal Changes in Breeding Activity, Testicular Size, Testosterone Concentration and Seminal Characteristics in Rams with Long or Short Breeding Season1

1984 ◽  
Vol 58 (2) ◽  
pp. 416-422 ◽  
Author(s):  
J. J. Dufour ◽  
M. H. Fahmy ◽  
F. Minvielle
Keyword(s):  
Seasonal Changes ◽  
Testosterone Concentration ◽  
Breeding Activity ◽  
Testicular Size

An intraruminal soluble glass bolus containing melatonin — a potential system for early lamb production

1997 ◽  
Vol 1987 ◽  
pp. 25-25
Author(s):  
A.L. Poulton ◽  
A.M. Symons ◽  
M.I. Kelly ◽  
J. Arendt
Keyword(s):  
Seasonal Changes ◽  
Commercial Application ◽  
Economic Pressure ◽  
Melatonin Secretion ◽  
Melatonin Treatment ◽  
Neural Signal ◽  
Breeding Activity ◽  
Soluble Glass ◽  
Potential System ◽  
The Hours

Seasonal changes in daylength (photoperiod) are effectively monitored by the eye transmitting a neural signal to the pineal gland which responds by secreting a hormone, melatonin, during the hours of darkness. Decreasing daylength is accompanied by an increase in the duration of melatonin secretion and stimulates breeding activity in sheep.It has been demonstrated that both timed (afternoon feeding and injection) and continuous (subcutaneous and vaginal implant) administration of supplementary melatonin to ewes in mid-summer mimics the effect of short or decreasing photoperiod and can advance the onset of breeding activity. Such treatments can also increase relative fecundity at early mating by phase-advancing the mid-breeding season peak in ovulation rate. As the U.K. is not sufficient in lamb production and bearing in mind the economic pressure for early lamb marketing, effective melatonin treatment offers considerable potential for commercial application.

Faecal testosterone concentrations and the acoustic behaviour of two captive male Australian fur seals

2009 ◽  
Vol 31 (2) ◽  
pp. 117 ◽  
Author(s):  
Joy S. Tripovich ◽  
Tracey L. Rogers ◽  
Geoff Dutton
Keyword(s):  
High Frequency ◽  
Seasonal Changes ◽  
Marine Mammals ◽  
Breeding Period ◽  
Testosterone Concentration ◽  
Acoustic Behaviour ◽  
Future Studies ◽  
Preliminary Information ◽  
Fur Seals ◽  
Hormonal Fluctuations

Seasonal changes in reproductive and acoustic behaviour are potentially affected by hormonal fluctuations; however, as it is difficult to routinely sample marine mammals, these associations are mostly inferred. Australian fur seals are vocal marine mammals that have a highly synchronous breeding season. The present study collected information on the testosterone concentration in faeces, vocalisations and behaviour of two captive male Australian fur seals to determine whether there are any associations between these variables. Positive associations were evident between the non-interactive agonistic behaviours (Head sway, Lay down and Head up) and an increase in calling rate of the bark calls in males. Barks were highest during August through to October, corresponding to the breeding period, while faecal testosterone levels peaked in September, coinciding with the high frequency in the calling rates of barks. Guttural threat calls were rarely heard throughout the year, but peaked in August. This call was not frequently heard but was associated with specific behaviours that were produced during more intense fighting interactions. This study presents preliminary information on the vocalisations, behaviour and hormone profiles for two captive Australian fur seals. Future studies with increased sample sizes from both wild and captive animals would clarify the intricate association between these factors.

scholarly journals Seasonal Changes in Spermatogenesis and Peripheral Testosterone Concentration in Raccoons (Procyon lotor) in Hokkaido

2012 ◽  
Vol 74 (6) ◽  
pp. 727-732 ◽  
Author(s):  
Minami W. OKUYAMA ◽  
Michito SHIMOZURU ◽  
Nobuhiro TAKAHASHI ◽  
Daisuke FUKUI ◽  
Ryohei NAKAMURA ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Procyon Lotor ◽  
Testosterone Concentration

Pubertal changes in testicular parameters and secretion of testosterone in Najdi and Naemi ram lambs under desert conditions

2017 ◽  
Author(s):  
Ahmed A. Al-kawmani ◽  
Mansour M. Alfuraiji ◽  
Saleh A. Kandeal ◽  
Mohammad Abul Farah ◽  
Khalid Mashai Alanazi
Keyword(s):  
Age Groups ◽  
Reproductive Capacity ◽  
Chronological Age ◽  
Testis Size ◽  
Age Group ◽  
Testosterone Concentration ◽  
Body Weights ◽  
Histological Appearance ◽  
Testicular Size ◽  
Ram Lambs

The present work was conducted to elucidate the relationships between chronological age, testosterone concentration and testis size of Najdi and Naemi ram lambs under desert conditions to determine the reproductive capacity of the above two breeds. The postnatal development of the seminiferous epithelium of the testes was also monitored. A total of 90 (45 Najdi and 45 Naemi lambs) aged between one and nine months, with five lambs at each month of age for each breed were used. The results showed that the testosterone concentration increased dramatically and rapidly between five and six months, followed by a period of gradual growth where testicular size was increased from 3 to 6 months of age. There was a significant (P > 0.05) difference in testosterone concentration (TC) and testis size (TS) in ram lambs between different age groups, similarly there were significant differences between body weights and lamb age between one and nine months. A positive correlation between the increasing body weight and the size of the testicle was observed. The testicles of lambs at each age-group had a different histological appearance except those of Najdi lambs at 2, 3 and 4 months and Naemi lambs at 2, 3, 4 and 5 months, where few differences were apparent. Small quantities were of spermatozoa appeared at the eighth month of age and increased in the ninth month. In conclusion, the current findings indicate that puberty in Najdi and Naemi rams occurs at the 8th and 9th month of age, respectively.

Seasonal changes in plasma testosterone concentration and mating activity in Border Leicester, Poll Dorset, Romney and Suffolk rams

1983 ◽  
Vol 23 (122) ◽  
pp. 248 ◽  
Author(s):  
MJ D'Occhio ◽  
DE Brooks
Keyword(s):  
Seasonal Changes ◽  
Extended Period ◽  
Field Conditions ◽  
Plasma Testosterone ◽  
Real Relationship ◽  
Mating Activity ◽  
Testosterone Concentration ◽  
Testosterone Levels ◽  
Seasonal Peak ◽  
Precise Time

Seasonal changes in the plasma testosterone profile and mating activity were compared for Border Leicester, Poll Dorset, Romney and Suffolk rams (three of each breed) maintained under field conditions at latitude 35�S. Border Leicester, Romney and Suffolk showed maximum testosterone levels from February to May. Peak mating activity occurred from March to August, but the precise time and duration of the peak differed between the three breeds. A correlation (r = 0.65, P<0 .05) existed between seasonal changes in plasma testosterone and mating activity in Border Leicester but not in Romney or Suffolk. However, in all three breeds, peak testosterone levels preceded peak mating activity by 1-2 months. Poll Dorset rams showed an extended period of high testosterone levels from August to March but no seasonal peak in mating activity. There was no real relationship, in any breed, between plasma testosterone concentration and mating activity for individual rams within any month.

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