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Papers by P. Chantaraprateep

The Thai Journal of Veterinary Medicine

Tropical Animal Health and Production, 2008

The aims of the current study were to illustrate figures for the characteristics of oestrous cycl... more The aims of the current study were to illustrate figures for the characteristics of oestrous cycles especially on follicular dynamics, corpus luteum and changes in progesterone and prostaglandin F2alpha, in the Holstein cross-bred dairy heifers. Twenty six healthy and sexual-mature virgin heifers were monitored for signs of oestrus. Their ovaries were sonically examined and the numbers and the sizes of the follicles as well as of the corpus luteum were documented. In our study, no difference in ratio of the 2-wave and 3-wave patterned cycle was evident. Seasons' change did not affect on characteristics oestrous cycles as well as on dynamics of follicles and corpus luteum. The heifers showed high variation in manifesting oestrus especially on a number of hours. The 'bodily' oestrous signs lasted longer than did 'behavioural' signs and connection of lowering of the back to standing oestrus was established. Certain diversities comparing to of existed dairy breeds were drawn for follicular dynamics, corpus luteum and its progesterone: 1) the 1st anovulatory dominant follicles showed higher growth rate and earlier exceeded dominant diameter; 2) the follicle tended to quicker ovulate but with a smaller diameter at ovulation; 3) the corpus luteum exhibited 4−16.5 mm in diameter of central cavity. Connecting to the levels of progesterone, 4) the corpus luteum turned into active, as well as mid-luteal, period quite late, and 5) the duration of the active period of the corpus luteum was shorter, but 6) at the end of the cycle-around the day of oestrus, progesterone remained certain low but significant levels. In conclusion, the Holstein cross-bred dairy heifers in our study faced a problem of delayed post-ovulatory progesterone rise of which underlying causes are needed to be further scrutinised either at endocrine or at cell levels.

15. Annual Veterinary …, 1988

Two surgical techniques of preparing teaser bulls in swamp buffalo and cattle had been performed.... more Two surgical techniques of preparing teaser bulls in swamp buffalo and cattle had been performed. Four cattle and one swamp buffalo bulls aged 1.5-2.0 years had surgically backward deflection of the penis from normal position to a position about 10-12 cm. posterior and ...

Thai Journal of Veterinary …, 1992

Strengthening research on animal reproduction and disease diagnosis in Asia through the application of immunoassay techniques, 1994

Forty-five dairy farms were randomly chosen among those with average to good management practices... more Forty-five dairy farms were randomly chosen among those with average to good management practices. Each of the total of 1265 cows was followed from calving to pregnancy. The herd health programme consisted of systematic examination of the key periods of the sexual cycle: at about 30 days post-partum to monitor uterine involution and to detect and treat uterine infection; at about 60 days post-partum to examine and treat anestrous animals, and following insemination, to test for pregnancy by assaying progesterone levels in milk samples collected on day 22 post-insemination and to examine and treat cows inseminated more than three times and still not pregnant (repeat breeders). Pregnancy diagnosis by examination per rectum was carried out at about 60 days post insemination. Manual recording of the age of animal, the number of the lactation, and conditions at calving (dystocia and retention of placenta) was done. Data from 1265 calvings were analysed. Reproductive performance before and after the application of the programme, as well as effects of extrinsic and intrinsic factors on pathology and reproductive ·performance, were also investigated. The results revealed that age at first calving was 31 ± 8 months. Dystocia, retained placenta, metritis and repeat breeding were the most common post-partum reproductive disorders found. Purebred dairy Bos taurus cows had the highest milk yield as well as the highest incidence of reproductive disorders. Conception rates to Al were higher from November to May, which coincided with the dry season. A high percentage of cows detected in oestrus were confirmed to be in the follicular phase by low progesterone. The adoption of the herd health scheme reduced calving to conception intervals from 186 ± 101 to 137 ± 80 days (P <0.001). The results show the effectiveness of such programmes in improving productivity and the importance of matching genotypes to the local environment. (Résumé d'auteur

Andrologia, 1979

LH and testosterone responses to gonadoliberin (LRH) were studied after previous dexamethasone an... more LH and testosterone responses to gonadoliberin (LRH) were studied after previous dexamethasone and testosterone propionate combined treatment (treated group) compared with a single dexamethasone previous treatment (control group) in 12 Montbéliarde bulls aged 15 months. This experiment was performed on two occaisions 6 months apart according to the same schedule. They included each time 6 bulls, treated with intramuscular injections of 400 mg testosterone propionate and 6 hours later 0.25 mg gonadoliberin together with the other 3 bulls. Testosterone propionate did not influence the mean LH response to gonadoliberin although mean testosterone levels before gonadoliberin injection was very low in the controls. These data suggest that (1) the previously reported depressing effect of dexamethasone on LH is not mediated by the low peripheral testosterone level and (2) under the conditions of this study, there is no short term effect of testosterone at the pituitary level.

This preliminary study has been performed on four young twin bulls, one pair aged 6 months and th... more This preliminary study has been performed on four young twin bulls, one pair aged 6 months and the other one aged 12 months. Plasma LH and testosterone were assayed from frequent blood sampling. Testosterone propionate (TP) following dexamethasone treatment did not significantly influence the LH response to gonadoliberin compared to the twin controls, although testosterone concentrations were high in those TP treated animals.

Australian Veterinary Journal, 1986

Animal Reproduction Science, 1981

This study was performed on six French Friesian bulls (aged 12 months at the onset of the experim... more This study was performed on six French Friesian bulls (aged 12 months at the onset of the experiment) on two separate occasions, 3 months apart and lasting 2 days each time. On each of both occasions, three bulls were submitted on the first day to an i.m. injection of dexamethasone (DXM, 20 mg) 6 h priot to a Luteinizing Hormone Releasing Hormone (LH-RH) challenge (0.250 mg i.m.) and the three others (control animals) to LH-RH only. On the second day, they all received a single LH-RH injection. The treated animals then served as controls on the second occasion and the controls as DXM—LH-RH treated individuals. Blood samples were taken at hourly intervals before LH-RH treatment (for 5 h), then every 15 min (for 2.5 h), and afterwards, every hour for 3 h. Androstenedione concentrations were significantly enhanced after LH-RH challenge in a similar manner on days 1 and 2 within groups, but the relative magnitude of the response in terms of area under the curve (ng/ml of plasma × 150 min) was lower in the DXM—LH-RH treated group than in the controls. In addition, the individual correlation between the testosterone and androstenedione responses was significant (P <0.05) in those animals treated but not in the controls. This study therefore suggests evidence of a double origin for androstenedione secretion, from the testes and probably from the adrenals.

Andrologia, 2009

Der Effekt von Dexamethason und Testosteronpropionat auf den LH‐Spiegel nach LRH‐Gabe bei jungen ... more Der Effekt von Dexamethason und Testosteronpropionat auf den LH‐Spiegel nach LRH‐Gabe bei jungen postpubertären Bullen

Theriogenology, 1981

Three swamp buffalo bulls aged 1.5, 1.10 and 2 years were submitted to frequent blood sampling ev... more Three swamp buffalo bulls aged 1.5, 1.10 and 2 years were submitted to frequent blood sampling every 15 m during a period of 25 h using an indwelling infusion set. Plasma LH and testosterone were quantified by radioimmunoassay technique. The levels of the two hormones in each individual exhibited episodic and nonrhythmic patterns. The number of LH peaks varied according to individual, ranging from no peak in one bull to 2 in the other two bulls. The mean LH concentrations during the period of study for each bull were 0.74, 0.33 and 1.17 ng/ml. Whereas the number of testosterone peaks varied between 1-10 and the average testosterone concentrations were 0.1, 0.33 and 0.55 ng/ml for the younger to the older bulls respectively. The testosterone peaks related to the LH peaks in each individual bull.

Australian veterinary journal, 1986

This experiment was conducted in order to compare the effects of injecting PGF2 alpha alone, PGF2... more This experiment was conducted in order to compare the effects of injecting PGF2 alpha alone, PGF2 alpha with oxytocin and placebo on the induction of farrowing in swine and to compare the relative effects of 3 different dosages of oxytocin (10, 20 and 30 iu per animal) when combined with PGF2 alpha (10 mg). The findings revealed that animals treated with 30 iu oxytocin farrowed within 10.6 h which was similar to those receiving PGF2 alpha only (9.4 h), but shorter than control animals (53.6 h). Animals receiving 20 and 10 iu of oxytocin farrowed within 1.4 and 1.7 h, respectively. Difficult farrowings requiring manual assistance occurred in 30%, 30%, 50% and 10% of sows given 30 iu, 20 iu and 10 iu of oxytocin and in the control group, respectively. Thirteen of 73 sows treated with PGF2 alpha farrowed within 12.6 +/- 5.3 h. Stillbirths were highest (10.2%) in the control animals whilst in the others it was under 7%. Oxytocin at dosages of 20 and 10 iu, seemed most promising in terms...