This study was conducted to characterize the profiles of LH, estradiol and progesterone hormones during oestrus in Dwarf goats. Five does were synchronized into oestrus with 2 intramuscular injections of PGF2 at an interval of 10 days. Blood samples were drawn at 8 h intervals from 0 to 77 h after second injection and hormones were estimated by radioimmunoassay (RIA). One of the does did not show oestrus. In two goats, LH rises were observed from hours 25-45 and attained peak levels at h-70 after second PGF2 injection. In two other does the rise in LH was significantly earlier and reached peak levels at 24-30 h. The concentration of LH ranged between 7.5 and 30 ng/ml (mean 19 ng/ml). The estradiol peaks in does were noticed at the same time as that of the LH. Estradiol concentrations varied between 9 and 16 pg/ml (mean 12 pg/ml). The progesterone remained at basal levels (0.1-0.2 ng/ml) throughout the oestrus in all animals. These results indicate that the estradiol and LH rises have temporal relationship with each other, rising almost at the same time and LH fall was earlier than estradiol

R. Kausar, S. A. Khanum and M. Hussain

Pakistan Veterinary Journal

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Pakistan Vet. J., 25(3): 2005 CHARACTERIZATION OF ENDOCRINE EVENTS AT OESTRUS  IN DWARF GOAT (CAPRA HIRCUS)  R. Kausar, S. A. Khanum and M. Hussain  Nuclear Institute for Agriculture and Biology (NIAB), P. O. Box 128,  Jhang Road, Faisalabad, Pakistan  ABSTRACT  This study was conducted to characterize the profiles of LH, estradiol and progesterone hormones during oestrus in Dwarf goats. Five does were synchronized into oestrus with 2 intramuscular injections of PGF2∝ at an interval of 10 days. Blood samples were drawn at 8 h intervals from 0 to 77 h after second injection and hormones were estimated by radioimmunoassay (RIA). One of the does did not show oestrus. In two goats, LH rises were observed from hours 25-45 and attained peak levels at h-70 after second PGF2 injection. In two other does the rise in LH was significantly earlier and reached peak levels at 24-30 h. The concentration of LH ranged between 7.5 and 30 ng/ml (mean 19 ng/ml). The estradiol peaks in does were noticed at the same time as that of the LH. Estradiol concentrations varied between 9 and 16 pg/ml (mean 12 pg/ml). The progesterone remained at basal levels (0.1-0.2 ng/ml) throughout the oestrus in all animals. These results indicate that the estradiol and LH rises have temporal relationship with each other, rising almost at the same time and LH fall was earlier than estradiol.   Key words: Oestrus, goat, progesterone, estradiol, LH.  INTRODUCTION  The Dwarf (Teddy) is one of the popular breeds of goat reared in Pakistan. It is an early maturing non-seasonal breeder having high reproductive efficiency (Prasad, 1979; Khanum et al., 2000). It has high prolificacy with 3 kiddings in two years (Srivastava et al., 1968; Khan et al., 1982). However, its milk production is poor and often insufficient to sustain adequate kid growth. The average body weight of adult males at one year of age is 22.98 ± 2.96 kg, whereas females of the same age weigh 13.91 ± 1.54 kg (NIAB Farm Data, 1992).  In Pakistan, where this breed plays an important role in the economy of the country, its reproductive physiology has not been well understood. Oestrus is a short phase of reproductive cycle in does, which involves some important events leading to ovulation. This phase can be manipulated to synchronize does in to a uniform group to prepare batch of kids, avoiding the severity of extreme seasons. Measurement of the concentrations of hormones associated with reproductive function and their temporal interrelationship can aid in the evaluation of reproductive status of does. The pre-ovulatory LH peak in the goat that occurs near the oestrus is preceded by a rise in the concentration of estradiol, 1 or 2 days before oestrus (Rawlings and Cook, 1993; Okada et al., 1996).   The coordination of all these phenomena is necessary for getting high fertility rates. These aspects of reproductive physiology of Dwarf goat have not been thoroughly studied in Pakistan. The purpose of this research was to study the hormonal profiles and their temporal interrelationship during oestrus period in Dwarf goats.   MATERIALS AND METHODS  Five Dwarf does, approximately one year of age and 12 to 14 kg weight, were selected at Biosaline Research Station, Lahore, Pakistan. Animals were allowed free grazing. The study was performed in October, 2003. The experimental animals were given two intramuscular injections (0.5 ml each) of Estrumate (Cloprostenol; a synthetic analogue of PGF2α at 125 ug/ml) at an interval of 10 days. The time of second injection was taken as 0 hour. After second injection an intact buck was introduced in the herd for oestrus detection. Blood sampling from the jugular vein of does was carried out from 0 to 77 h after second injection with an interval of 8 hours. Serum was separated by centrifugation (2000 rpm, 15 min) and frozen in plastic capped tubes at -20oC until analysis.  The serum progesterone and estradiol concen-trations were determined by solid-phase radioimmunoassay (RIA) kits (coat-A-count progesterone and estradiol; Diagnostic Products  143Pakistan Vet. J., 25(3): 2005 144Corporation, 5700 West 96th Street, Los Angeles, CA 90045). The sensitivity of the assays for progesterone and estradiol were 0.015 ng/ml and 0.69 pg/ml, respectively.  LH was assayed by a double-antibody RIA method (Kanai and Ischikawa, 1988). For this assay NIDDK-ovine LH was used for radioiodination and standard preparation, rabbit anti-ovine LH serum as the first antibody, and goat anti-rabbit gammaglobulin as the second antibody. The sensitivity of the assay was 0.1 ng/ml. The intra-assay and inter-assay coefficients of variation were 6.77 and 0.12%, respectively.   RESULTS AND DISCUSSION  In the present study, in two goats, LH rises were observed from 25-45 h and LH attained peak levels at h-70 after second PGF2∝ injection (Fig. 1A and B). While in other two goats LH reached peak levels at 24-30 h after second PGF2∝ injection (Fig. 1C and D).  The peak concentrations of LH ranged between 7.5 and 30 ng/ml (mean 19 ng/ml). However, one doe did not show oestrus.  These results conform to those of some earlier findings on charachterization of endocrine events during oestrus in goat. Medan et al. (2004) reported oestrus at 55.2 ± 2.3 h and LH surge occurred at 62.8 ± 1.4 h after PGF2α injection in goats. In another study with Canary goats (Gonzalez-Valle et al., 1998), the total interval from progesterone sponge withdrawal to LH peak has been reported as 77.5 ± 0.9 h and its peak level averaged 44 ± 5.3 ng/ml.  Estradiol peak was observed at h-70 in two does in which LH peak was also observed at h-70 after second PGF2∝ injection (Fig. 1A and B). In 2 other does, estradiol was found to have peak levels at h-24 and 30. Estradiol peak concentrations varied between 9 and 16 pg/ml (mean 12 pg/ml). The LH and estradiol rises were found to have intimate temporal relationship with each other, rising almost at the same time. However, the LH fall was earlier than the estradiol fall in two animals (Fig. 1A and D), whereas in two other goats fall in LH    Fig. 1: Serum profile of LH (▼;ng/ml), progesterone (*; ng/ml) and estradiol             (♦; pg/ml) in four Dwarf goats (A, B, C and D) during oestrus period Pakistan Vet. J., 25(3): 2005 145and estradiol was at the same time (Fig. 1B and C).  The estradiol levels during oestrus phase of other does and sheep were found comparable to the levels in Dwarf goats. Blaszczyk et al. (2004) has reported plasma estradiol levels in goats during induced estrus as 15.3 ± 5.0 pg/ml in autumn and 12.3 ± 3.8 pg/ml in spring. The sequence of changes in the estradiol level and its temporal relationship with LH as observed in this study is almost similar to that observed in Finn-Merino ewes (Campbell et al., 1990).  The progesterone concentrations remained at basal levels of 0.1-0.2 ng/ml throughout the oestrus, as observed by others (Zarkawi, 2000; Khadiga et al., 2005). The fall in basal level of progesterone was found coincident with the increase in estradiol level. This was in agreement with the Pant et al. (1977), who reported that the decline in the concentration of progesterone 12 hours before oestrus was coincided with the increased estradiol concentration. Tanaka et al. (1995) suggested that after luteolysis, GnRH pulse generation becomes fully potentiated to induce the final follicular development and to stimulate estradiol secretion, which eventually provokes the induction of the preovulatory LH surge and hence ovulation.   It was concluded that LH and estradiol peaks have remarkable temporal relationship at oestrus in Dwarf goat, rising almost at the same time, while progesterone remains at basal level. However, due to pulsatile secretion pattern and short duration of LH peak observed in conjunction with ovulation in most domestic species, the frequency of sampling requires to be in the order of 10 minutes to ensure detection of all the pulses (IAEA Technical Report Series No. 233, 1984). So it was felt that frequent sampling is required to substantiate these results.  Acknowledgements Authors acknowledge IAEA for supplying RIA kits, NIDDK (National Institute of Diabetes and Digestive and Kidney Diseases, USA) for providing ovine LH and antiserum for ovine LH and Professor Naoto Ishikawa (Institute of Agriculture and Forestry, University of Tsukuba, Japan) for providing second antibody.  REFERENCES  Blaszczyk, B., J. Udala and D. Gaczarzewicz, 2004. Changes in estradiol, progesterone, melatonin, prolactin and thyroxine concentrations in blood plasma of goats following induced estrus in and outside the natural breeding season. Small Rumin. Res., 51: 209-219. Campbell, B. K., G. E. Mann, A. S. McNeilly and D. T. Baird, 1990. The pattern of ovarian inhibin, estradiol and androstenedione during the estrous cycle of the ewe. Endocrinology, 127: 227-235. Gonzalez-Valle, F., M. Batista-Arteaga and A. Gracia-molina, 1998. Follicular atresia and LH concentrations during the follicular phase of the estrous cycle in the goat (Capra hircus). Anim. Reprod. Sci., 51: 23-30. IAEA Technical Report Series No 233, 1984. General introduction to radioimmunoassay. Laboratory Training Manual on Radioimmunoassay in Animal Reproduction, pp: 85-111.   Kanai, Y. and N. Ischikawa, 1988. Pulsatile secretion of luteininzing hormone and plasma levels of ovarian steroids during the estrous cycle in the Shiba goat. Japan J. Anim. Reprod., 34: 105-110.  Khadiga, M. G., K. G. Mohamed and F. T. Doaa, 2005. The hormonal profile during the estrous cycle and gestation in Damascus goats. Small Rumin. Res., 57: 85-93.  Khan, B. B., M. Younas and S. H. Hanjra, 1982. Breeds and types of livestock in Pakistan. Univ. Agri., Faisalabad, Pakistan. Khanum, S. A., M. Hussain, M. Ali, R. Kausar and A. M. Cheema, 2000.  Age at puberty in female Dwarf goat kids and estrous cycle length on the basis of hormones. Pakistan Vet. J., 20: 71-76. Medan, M. S., G. Watanabe, K. Sasaki and K. Taya, 2004. Transrectal ultrasonic diagnosis of ovarian follicular cysts in goats and treatment with GnRH. Domestic Anim. Endocrinol., 27: 115-124  NIAB Farm Data, 1992. Average of the body weight in the groups of females and males of Dwarf goat at different ages. Inst. Agri. Biol. (NIAB), Faisalabad, Pakistan. Okada, M., H. Tomohiro, T. Yakari and Y. Mori, 1996. Timing of proceptive and receptive behaviour of female goats in relation to preovulatory LH surge. J. Vet Med. Sci., 58: 1085-1089. Pant, H. C., C. R. Hopkinson and R. J. Fitzpatrick, 1977. Concentrations of oestradiol, progesterone, luteinizing hormone and follicle stimulating hormone in the jugular venous plasma of ewes during the estrous cycle. J. Endocrinol., 73: 247-255. Prasad, S. P., 1979. A note on the characteristics of postpartum estrous in Barbari nannies. Indian J. Anim. Sci., 49: 583-585. Rawlings, N. C. and S. J. Cook, 1993. LH secretion around the time of the preovulatory gonadotrophin surge in the ewe. Anim. Reprod. Sci., 30: 289-299. Srivastava, V. K., B. C. Riazada and V. A. Kulkarni, 1968. Carcass quality of Barbari and Jamnapari type goats. Indian Vet. J., 45: 219–225.  Tanaka, T., T. Ozawa, K. Hoshino and Y. Mori, 1995. Changes in the gonadotropin-releasing hormone pulse generation activity during the estrous cycle in the goat. Neuroendocrinology, 62: 553-561.   Zarkawi, M., 2000. The evaluation of two doses of prostaglandin F2 analogue, prosolvin, for oestrous synchronization of Syrian Awassi ewes. New Zealand J. Agri. Res., 43: 509-514.  

CHARACTERIZATION OF ENDOCRINE EVENTS AT OESTRUS IN DWARF GOAT (CAPRA HIRCUS)

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CHARACTERIZATION OF ENDOCRINE EVENTS AT OESTRUS IN DWARF GOAT (CAPRA HIRCUS)

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