Sexual development and the effects of active immunization against GnRH in Chinese Tanyang ram lambs

2003 ◽  
Vol 77 (3-4) ◽  
pp. 129-139 ◽  
Author(s):  
S. Cui ◽  
Y.F. Chen ◽  
H.N. Yue ◽  
Y.Q. He ◽  
A.S. McNeilly
Keyword(s):  
Sexual Development ◽  
Active Immunization ◽  
Ram Lambs

Responses of ram lambs to active immunization against testosterone and luteinizing hormone-releasing hormone

1982 ◽  
Vol 242 (3) ◽  
pp. E201-E205 ◽  
Author(s):  
B. D. Schanbacher
Keyword(s):  
Luteinizing Hormone ◽  
Live Weight ◽  
Active Immunization ◽  
High Serum ◽  
Testicular Development ◽  
Serum Concentrations ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Antibody Titers ◽  
Ram Lambs

Active immunization of young ram lambs against testosterone and luteinizing hormone-releasing hormone (LHRH) was shown to block the growth attributes characteristic of intact ram lambs. Testosterone and LHRH-immunized lambs grew at a slower rate and converted feed to live weight gain less efficiently than albumin-immunized controls. Lambs immunized against testosterone and LHRH had high antibody titers for their respective antigens. Moreover, testosterone-immunized lambs had high serum concentrations of luteinizing hormone (LH) and testosterone, whereas LHRH-immunized lambs had low to nondetectable serum concentrations of these hormones. Release of LH and testosterone following the intravenous administration of LHRH (250 ng) was absent in LHRH-immunized lambs, but quantitatively similar for intact and albumin-immunized control lambs. Testosterone-immunized lambs responded as did conventional castrates with a large LH release, but testosterone concentrations were unchanged. These findings are discussed relative to the integrity of the hypothalamic-pituitary-testicular endocrine axis and the importance of gonadotropin support for normal testicular development. These data show that LHRH immunoneutralization effectively retards testicular development and produces a castration effect in young ram lambs.

scholarly journals Active immunization against GnRH in pre-pubertal domestic mammals: testicular morphometry, histopathology and endocrine responses in rabbits, guinea pigs and ram lambs

animal ◽  
2018 ◽  
Vol 12 (4) ◽  
pp. 784-793 ◽  
Author(s):  
P.M. Aponte ◽  
M.A. Gutierrez-Reinoso ◽  
E.G. Sanchez-Cepeda ◽  
M. Garcia-Herreros
Keyword(s):  
Guinea Pigs ◽  
Active Immunization ◽  
Ram Lambs

Puberty and early sexual development in Libyan fat-tailed ram lambs

1989 ◽  
Vol 145 (3) ◽  
pp. 276-288 ◽  
Author(s):  
M.O.K. Madani ◽  
M.S. Rahal ◽  
M.T. Zawia ◽  
B.A. Eluwhaishi
Keyword(s):  
Sexual Development ◽  
Ram Lambs

A study of sexual development in ram lambs

1986 ◽  
Vol 43 (3) ◽  
pp. 459-468 ◽  
Author(s):  
F. M. S. Al-Nakib ◽  
G. A. Lodge ◽  
J. B. Owen
Keyword(s):  
Body Weight ◽  
Testosterone Level ◽  
Sexual Development ◽  
Sexual Maturity ◽  
Semen Quality ◽  
Plasma Testosterone ◽  
Artificial Rearing ◽  
Sexual Characteristics ◽  
Ram Lambs ◽  
Mating Performance

ABSTRACTTwo experiments were designed to study the effect of rearing method, female company, and repeated libido and semen tests on the pattern of sexual development of ram lambs. Four artificial rearing treatments (AR) were compared with natural rearing (NR) in one experiment and four artificial compared with three natural rearing treatments in a second experiment. Lambs on AR treatments in both experiments, as well as naturally reared lambs in the second experiment, were reared with or without females either before and/or after weaning. Half the lambs in the second experiment were libido and semen tested, and their mean plasma testosterone level was also measured, while the rest were only tested at the end of the experiment. The effect of method of rearing and female company on body growth, testes diameter, libido and semen quality were also investigated.A close relationship was found between body weight and sexual characteristics (for example, testis diameter, semen traits, libido, testosterone level and age at the onset of sexual maturity). NR resulted in faster growth than AR but was not appreciably different from early weaned-naturally reared treatments. It was also observed that mating performance improved steadily with advancement in age and increase in body weight. The onset of sexual maturity was attained at a minimum of 23 kg body weight and a minimum of 198 days of age. However, the heavier the lamb when sexually mature, the better its mating performance.Previous libido tests of ram lambs improved their subsequent mating performance, but had no effect on semen quality. However, libido tests did not improve the performance of those ram lambs which did not exhibit initial libido.It is suggested that early weaning at 2 months of age could be a suitable system for ram lambs weaned off their mothers for breeding purposes. These lambs should be reared as an all-male group but libido tested at monthly intervals commencing at 3 months of age. The criteria for selecting these lambs at an earlier age should be body weight and testis diameter.

Reduction of testicular parenchyma at marking: effect on lamb growth, carcass fatness and sexual development

1991 ◽  
Vol 31 (5) ◽  
pp. 597 ◽  
Author(s):  
DL Hopkins ◽  
RB Jackson ◽  
KL Saunders
Keyword(s):  
Sexual Development ◽  
Similar Rate ◽  
Tissue Growth ◽  
The Other ◽  
Lean Tissue ◽  
Ewe Lambs ◽  
Carcass Parameters ◽  
Viable Sperm ◽  
Ram Lambs ◽  
Lamb Growth

Growth and carcass parameters were studied for 296 lambs comprising 141 males and 155 ewes. The males were either castrated (wethers) or vasectomised and hemicastrated with the parenchyma of the retained testicle reduced (cryptorchids), or they had the parenchyma of both testicles reduced (rams). Wether and ram lambs grew at a similar rate, the latter group growing significantly (P<0.05) faster to first slaughter than cryptorchid and ewe lambs. Ewe lambs grew significantly (P<0.05) slower than those from the other groups. Ewe lambs were significantly (P<0.05) fatter at slaughter than lambs in all other groups, and wether lambs were fatter (P<0.05) than the cryptorchid and ram lambs. Sexual competency of the cryptorchid and ram lambs was assessed by testicle examination, which showed that the cryptorchid lambs were not likely to produce viable sperm. In contrast, there was evidence that the treatment applied to the ram lambs would not prevent production of viable sperm, and they had the potential to sire lambs. This fertility was attributed to the retention of the scrotal sac. The technique used for the cryptorchid lambs involving scrotal ablation was deemed to offer the most potential in terms of lean tissue growth tempered against sexual competency and development of undesirable male characteristics.

A note on mating ability in clun forest ram lambs

1972 ◽  
Vol 14 (2) ◽  
pp. 259-262 ◽  
Author(s):  
Ó. R. Dýrmundsson ◽  
J. L. Lees
Keyword(s):  
Body Weight ◽  
Sexual Development ◽  
Mating Behaviour ◽  
Late Summer ◽  
Seasonal Influence ◽  
Mating Ability ◽  
Breeding Activity ◽  
Wide Range ◽  
Ram Lambs

SUMMARYSome aspects of sexual development and mating behaviour in Clun Forest ram lambs having a wide range of birth dates were studied during two seasons. The 61 ram lambs studied were introduced individually to Clun ewes in oestrus, for short periods at fortnightly intervals during late summer and autumn. Complete matings, i.e. intromission and ejaculation, were first achieved at a mean age of 6 months (range 142–223 days) and a mean body weight of 35 kg (range 24–49 kg). The attainment of physiological puberty preceded the first copulation, often by several weeks. A few individuals had abnormal testes and were partly or completely sterile, but exhibited normal mating behaviour. Early-born lambs tended to complete their first matings at a higher age and heavier body weight than late-born lambs, which suggests a possible seasonal influence on the development of breeding activity in the ram lamb.

Puberal development of Clun Forest ram lambs in relation to time of birth

1972 ◽  
Vol 79 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Ó. R. Dýrmundsson ◽  
J. L. Lees
Keyword(s):  
Body Weight ◽  
Sexual Development ◽  
Body Growth ◽  
The Body ◽  
Chronological Age ◽  
Testicular Development ◽  
Stage Of Development ◽  
Body Development ◽  
Ram Lambs ◽  
The Right

SUMMARYSome aspects of sexual development and the attainment of puberty in Clun Forest ram lambs were studied during the two seasons 1970–1. Strong correlations existed between parameters of penial, scrotal and testicular development. Sexual development in general appeared to be more closely associated with the body growth than the chronological age of the ram lamb.Nevertheless, marked variation existed in both age and body weight at puberty. Although the majority of the lambs attained this stage of development at 4·5–5 months the age-range extended from 99 to 176 days. The mean body weight at puberty was 32·5 kg, ranging from 24·5 to 38·0 kg. There appeared to be an interaction between chronological age and general body development in relation to the appearance of sperm in the epididymides. Not only did it seem that a certain degree of body growth and testicular size was required before spermatozoa could be released, but also a limit of chronological age below which puberty was not attained. Large differences existed between individual lambs in both testicular and epididymal weights at puberty. There was a high degree of symmetry in growth between the left and the right testes and epididymides.Time of birth influenced the pattern and rate of body growth and sexual development. This seemed to be largely due to seasonal fluctuations in nutritional conditions during rearing but the results obtained do not preclude the possibility that other seasonal factors, such as the daylight environment experienced by the ram lamb, might have a certain limited influence on sexual development.

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