Endocrine Profiles of Oestrous Cycle in Buffalo: A Meta-analysis

Transcription

1 69 Asan-Aust. J. Anm. Sc. Vol. 23, No. 2 : February 200.ajas.nfo Endocrne Profles of Oestrous Cycle n Buffalo: A Meta-analyss S. Mondal*, K. P. Suresh and S. Nand Natonal Insttute of Anmal Nutrton and Physology, Adugod, Bangalore , Inda ABSTRACT : A meta-analyss as conducted to summarze the results of studes hch have descrbed the profles of hormones durng the oestrous cycle n buffalo usng a fxed effect model and a random effect model. Plasma progesterone concentratons ere loest (0.30±0.06 ng/ml) durng the per-oestrous phase and ncreased (p = 0.067) through the early luteal phase to a maxmum concentraton (.94±0.03 ng/ml) durng the md-luteal phase. Crculatng plasma nhbn and estradol concentratons ere loest (0.3±0.0 and.04±0.3 ng/ml) durng the md-luteal phase, ncreased through the late luteal phase to maxmum concentratons (0.44±0.02 and 22.48±0.32 ng/ml) durng the per-oestrous phase. Plasma FSH concentratons ere loest durng the early luteal phase and ncreased through the md-luteal phase to a maxmum concentraton durng the per-oestrous phase. Perpheral prolactn concentratons ere loest durng the late luteal phase and ncreased to a maxmum concentraton durng the per-oestrous phase hch then declned (p = 0.76) durng the early luteal phase. Perpheral plasma cortsol concentratons decreased from 2.68±0.4 ng/ml durng the early luteal phase to.43±0.27 ng/ml durng the md-luteal phase (p<0.00) hch then ncreased to 2.06±0.7 ng/ml durng the late luteal phase. Plasma T 3 concentratons decreased from the late luteal phase to the per-oestrous phase (p<0.00) hch then ncreased durng the early luteal phase. T 4 concentratons ncreased from the late luteal phase to the per-oestrous phase hch then decreased durng the early luteal phase. (Key Words : Meta-analyss, Buffalo, Fxed Effect Model, Random Effect Model, Oestrous Cycle) INTRODUCTION Buffalo s the prncpal dary anmal n the developng countres of Asa and the manstay of the Indan dary ndustry, contrbutng over 60% of the total mlk producton. Inda produces about to-thrds of the orld s buffalo mlk and nearly half of the orld s buffalo meat (FAOSTAT, 2005). Problem of slent heat coupled th late maturty, poor expresson of estrus, rregular oestrous cycle, seasonalty n breedng, anestrous, lo concepton rate, long postpartum nterval, repeat breedng are some of the major constrants n buffalo productvty and mprovement through artfcal breedng (Madan, 990). Slent estrus s one of the major mpedments n understandng reproductve parameters and asssted reproducton n ths speces (Mondal et al., 2003b; Mondal and Prakash, 2003c; Mondal et al., 2008b). Buffalo tends to exhbt overt sgns durng nght or early mornng and most farmers are gnorant of physcal sgns of oestrous. The nherently suboptmal functonng of hypothalamo-hypophysal-gonadal axs and consequently lo crculatng hormones mght be * Correspondng Author: S. Mondal. Tel: , Fax: , E-mal: sukanta78@gmal.com Receved March 24, 2009; Accepted June 4, 2009 responsble for hgher ncdence of nactve ovares and true anestrous n buffalo. Oestrus detecton s also dffcult n buffaloes due to lack of expert personnel, varaton n duraton of oestrous and reluctance of some teaser bulls to mate. Therefore, an understandng of oestrous expresson mechansm n terms of endocrne modulatons ll form the bass for elucdatng the causes of loer reproductve effcency n buffalo. The dfferent phases of reproductve cycle are regulated by ntrcate sequental events and nteracton beteen hypothalamc releasng factors from the ptutary and sex sterods. Lack of ntegraton or synchronzaton and endocrne mbalances at any phase of the sequence may result n reproductve falure. Progesterone as a marker for montorng of functonal status of corpus luteum and dagnostc tool for dentfyng ovaran condton such as oestrous confrmaton, slent oestrous, lack of cyclcty have been reported (Foote et al., 979; Claus et al., 983; Mondal and Prakash, 2002; Mondal et al., 2003b; Mondal and Prakash, 2003c; Mondal et al., 2008b). Estrogen nduces behavoural symptoms of oestrous by ts acton on the central nervous symptom (Hafez, 974). Ptutary FSH s essental for development and mantenance of ovaran follcles n sngle and multple ovulatng speces (Taya et al.,

2 70 Mondal et al. (200) Asan-Aust. J. Anm. Sc. 23(2): ). Inhbn, produced by granulosa cells of ovaran follcles, s a glycoproten hormone hch suppresses producton and/or secreton of FSH through negatve feedback at ptutary level (Burger, 992). In the last to decades consderable attenton has already been focused on reproductve endocrnology as a means to dentfy specfc problems and devse means to augment productve performance. Meta-analyss s a statstcal tool that allos the quanttatve ntegraton of results from publshed studes that nvolve certan amount of dfferences, such as physologcal status of anmal, expermental desgn and measurement methods among other. Results from sngle classcal experment cannot be the bass for a large nference space because the condtons under hch observatons are made n a sngle experment are generally very narro. A sngle expermentaton measures the effect of one or a very fe factors hle mantanng all other factors as constant as possble. Often the experments are repeated by others to verfy the generalzaton and repeatablty propertes of the observatons that ere made and to challenge the range of applcablty of observed results and conclusons. There are lots of laboratory-tolaboratory varatons and there s a need to summerze the results across all publshed studes descrbng the profles of varous hormones n buffalo. The objectve of ths study as to ntegrate and consoldate statstcally the endocrne factors regulatng the cyclcty n buffalo by conductng a meta-analyss of publshed results. MATERIALS AND METHODS Artcles publshed ere sought usng the on-lne journal databases Web of Scence (ISI, UK), CAB (CABI Publshng) and VET CDs. Artcles ere also found by cross-referencng ctatons n retreved artcles. No unpublshed study as consdered. About 45 peer reveed studes elaboratng the hormone profles ere searched and 25 studes hch satsfed the follong crtera ere ncluded n meta-analyss (Table ). The crtera for selectng the studes ere () oestrous cycle, () buffalo () sterod and proten hormones and (v) radommunoassay. Gven a vast quantty of heterogeneous lterature, the type of tems that ere collected nclude the characterstcs on the report of the study (such as author, year and source), the study tself, research desgn (expermental or observatonal, treatment assgnment mechansm or samplng mechansm, attrton rate or non-response rate). After testng for sgnfcance of heterogenety of studes Table. Studes on endocrne profles durng oestrus cycle consdered for meta-analyss Sl. No. Author Year No of anmals Hormones studed Arora and Pandey Progesterone, Estradol, LH 2 Ahmed et al Progesterone 3 Bachalaus et al Progesterone, Estradol 4 Batra and Pandey 982/83 7 Estradol, LH 5 Batra et al Progesterone 6 Batra et al Estradol 7 Kamboj and Prakash Progesterone 8. Kana and Shmzu LH, Progesterone, Estradol 9 Khurana and Madan T3 and T4 0 Kumar et al Progesteron, Estradol, LH, T3, T4 Madan et al Progesterone 2 Palta et al Inhbn 3 Rao and Pandey Progesterone 4 Rao and Pandey Estradol, LH 5 Mondal and Prakash Progesterone 6 Mondal et al. 2003a 2003b 2003c Progesterone, Inhbn Inhbn Progesterone 7 Mondal et al Progesterone 8 Mondal et al. 2008a 5 FSH 2008b 9 Paha and Pandey Progesterone, Estradol 20 Paha and Pandey 984 Prolactn 2 Palta et al Inhbn, Progesterone 22 Sharma et al Progesterone, Estradol FSH, T3, T4

3 Mondal et al. (200) Asan-Aust. J. Anm. Sc. 23(2): based on ch-square test and Tau 2 (heterogenety coeffcent), fxed effect model or random effect model as selected for ntegratng the results. When heterogenety as nsgnfcant, fxed effect model by Inverse varance method as used th zero heterogenety co-effcent, otherse a random effect model by DerSmonan and Lard Method. Random effect model allos the study varaton by coeffcent of heterogenety to some extent hle ntegratng results and n the present study, the maxmum Tau 2 s alloed as 20 so as to avod the larger heterogenety among the studes (Glass, 976; Cooper and Hedges, 994; Eugene et al., 2004; Sauvant et al., 2008). Inverse-Varance Method: The Inverse-Varance Method (IV method) as used to pool ether bnary, contnuous or correlaton data. Ths approach has de applcablty snce t can be used to combne any estmate that has standard error avalable. The effect sze or mean are combned to gve a pooled estmate (denoted by θ) by calculatng eghted average of the treatment effects from the ndvdual studes as follos. θ = IV θ Where the eghts are calculated as, = 2 SE(θ ) That s, the eght for the th study s equal to ts precson of the estmate. The standard error of θ IV s gven by, SE(θ ) = IV The heterogenety statstc (denoted by Q ) s gven by, Q = (θ - θ ) IV 2 The Q follos ch-square dstrbuton th (k-) degrees of freedom, here k s the number of studes ncluded n the meta-analyss. DerSmonan and Lard Method: The DerSmonan and Lard method (DL method) of meta-analyss s based on the random effects model. Under the random effects model, the assumpton of common effect s relaxed, and the effect sze or mean θ are assumed to have a normal dstrbuton th mean θ and varance τ 2. The usual DL estmate for τ 2 s gven by, τ = 2 Q - (k - ) - 2 here, Q s the heterogenety statstc, and the eghts are calculated as n the IV Method, and k s the number of studes. The τ 2 s set to zero f Q <(k-). In ths approach, the eghts for each study effect sze are as gven belo. = 2 2 SE( θ ) + τ The pooled estmate s gven by, θ = DL θ Wth standard error, SE(θ ) = DL The heterogenety statstc and ts test of sgnfcance s as gven n the I V method. RESULTS Perpheral plasma concentratons of progesterone ranged beteen 0.3±0.06 to.94±0.03 ng/ml durng oestrous cycle n buffalo. Plasma levels hch ere loest (0.30±0.06 ng/ml; Tau 2 = 0.025) durng peroestrous phase ncreased to 0.47±0.07 ng/ml (p = 0.067) durng early luteal phase and then further to.94±0.03 ng/ml (Tau 2 = 0; p<0.00) durng md luteal phase. The concentraton declned thereafter to.24±0.02 ng/ml (Tau 2 = 0) durng late luteal phase. Plasma estradol concentratons ere maxmum (22.48±0.32 pg/ml; Tau 2 = 5.93) durng peroestrous phase and declned (p<0.00) to.04±0.3 pg/ml (Tau 2 = 0) durng md luteal phase and ncreased to 2.29±0.2 pg/ml (Tau 2 = 0; p<0.00) durng late luteal phase. Plasma concentratons of FSH ere found to range beteen 0.98±0.3 to 2.45±0.33 ng/ml. FSH concentraton ere loest (0.98±0.3 ng/ml; Tau 2 = 0) durng early luteal phase and ncreased to 0.99±0.22 ng/ml (Tau 2 = 0; p = 0.969) durng md luteal phase. The concentraton further ncreased to.55±0.27 ng/ml (Tau 2 = 0; p = 0.252) durng late-luteal phase and then to the peak level of 2.45±0.33

4 72 Mondal et al. (200) Asan-Aust. J. Anm. Sc. 23(2):69-74 ng/ml (Tau 2 = 0; p = ) durng peroestrous phase. Perpheral plasma nhbn and cortsol concentratons decreased from 0.44±0.02 and 2.68±0.25 ng/ml durng peroestrous phase to 0.34±0.0 (Tau 2 = 0.003; p<0.00) and 2.68±0.4 ng/ml (Tau 2 =.2; p = 0.999) durng early luteal phase hch then declned to 0.3±0.0 (Tau 2 = ; p = 0.06) and.43±0.27 (Tau 2 = 2.07; p<0.00) ng/ml durng md luteal phase, respectvely. The concentratons then ncreased to 0.39±0.02 (Tau 2 = 0.05; p = 0.004) and 2.06±0.7 (Tau 2 = 0.36; p = 0.057) ng/ml, respectvely durng late luteal phase. Plasma prolactn concentratons ranged beteen 29.28±25.4 to 245±23.3 ng/ml throughout the oestrous cycle. Perpheral prolactn concentratons ere loest (29.28±25.4 ng/ml) durng late luteal phase and ncreased to a maxmum concentraton (245±23.3 ng/ml; p = 0.552) durng peroestrous phase hch then declned to 227.7±30.9 ng/ml (p = 0.76) durng early luteal phase n buffalo. Fxed effect model as used as the heterogenety as not statstcally sgnfcant and Tau 2 as zero. In the present study, mean plasma T 3 concentratons have been reported to vary beteen.04±0.04 to.45±0.09 ng/ml and T 4 concentraton beteen 44.78±0.64 to 48±.38 ng/ml durng the oestrous cycle. Plasma T 3 concentratons ere.45±0.09 ng/ml durng the late luteal phase hch then decreased (p<0.00) to.04±0.04 ng/ml durng peroestrous phase. The concentraton then ncreased to.2±0.05 and.2±0.04 ng/ml durng early luteal and md luteal phase, respectvely. T 4 concentratons ere 46.54±. ng/ml durng late luteal phase and ncreased to (p = 0.44) to 48±.38 ng/ml durng peroestrous phase. The concentratons then decreased to 44.78±0.64 ng/ml (p = 0.039) durng early luteal phase folloed by an ncrease to 49.8±0.64 ng/ml (p<0.00) durng md luteal phase of oestrous cycle. Meta-analyss usng the fxed effect model as used n both T 3 and T 4 concentratons as the heterogenety beteen the studes consdered s not statstcally sgnfcant (p>0.05). DISCUSSION To the best of our knoledge and belef, ths s the frst study to report the meta-analyss of hormonal profles of oestrous cycle n buffalo. Meta-analyss s used ncreasngly as a method of summarzng data that tests the same hypothess n several dfferent publshed studes. The valdty of a choce of meta-analytcal methods depends on pattern of varablty (heterogenety) observed n the study results. Hoever, there s no emprcal gudance currently avalable to judge hch methods are approprate n hch crcumstances so as to yeld better results. Therefore, the present study has made an attempt to provde approprate meta-analytcal methods to deal th the hormone profles durng oestrous cycle n buffalo. In the present study, plasma progesterone concentratons, hch ere loest durng the peroestrous phase, ncreased through early luteal phase to a maxmum concentraton durng md luteal phase n Murrah buffaloes. These results are n agreement th earler observatons n cattle (Schomberg et al., 967; Gupta and Pope, 968) and buffaloes (Bachalaus et al., 979; Arora and Pandey, 982; Mondal et al., 2003a; Mondal et al., 2004) n terms of mnmum level on the day of oestrous th gradual rse to the hgher levels durng luteal phase and then declnng to basal level at subsequent oestrous. The cyclc pattern of progesterone concentratons n jugular plasma follos the knon changes n corpus luteum functon n buffalo durng oestrous cycle. Lke cattle (Mares et al., 962), the declne n progesterone levels toards the end of the cycle and a sharp rse durng luteal development suggest that functonng of corpus luteum can be montored by progesterone determnaton. Smlarly n cattle and buffalo that exhbted overt oestrous and slent oestrous, progesterone level as loest durng peroestrous phase and ncreased to maxmum concentraton durng md luteal phase (Mondal et al., 2003c; Mondal et al., 2003d). Plasma nhbn, FSH and estradol concentraton ere loest durng the md luteal phase, ncreased through the late luteal phase to a maxmum concentraton durng the peroestrous phase. The patterns of nhbn concentraton agrees th earler report n cattle (Kaneko et al., 995) and buffalo (Palta et al., 997; Mondal et al., 2003a; Mondal et al., 2003b) n terms of an ncrease n nhbn levels durng the follcular these of oestrous cycle. The follcular groth occurs n a ave-lke pattern, th a predomnance of to aves n cattle (Person and Gnther, 988; Gnther et al., 989) and buffalo (Mank et al., 998). The frst and second aves start at Days and, respectvely (Day 0 = Day of ovulaton) n cattle (Person and Gnther, 988; Gnther et al., 989) and at Days 0.20 and 9.20, respectvely, n buffaloes (Mank et al., 998). Each ave s marked by the emergence of a domnant follcle and a cohort of subordnate follcles. The concentratons of plasma FSH have been reported to be hgh pror to the emergence of each follcular ave and reman lo durng the grong phase of a domnant follcle (Kaneko et al., 995). In the present study also, the hghest crculatng concentratons of FSH ere observed at Day 0 (day of oestrous). Follong a decrease thereafter, crculatng FSH concentratons rose agan and reached hgh concentratons on Days 7 n buffalo pror to the emergence of the second ave. The concentratons of nhbn have been reported to reach a hgh level th the emergence of each ave, n the grong

5 Mondal et al. (200) Asan-Aust. J. Anm. Sc. 23(2): phase of the domnant follcle and decrease hen the domnant follcle ceases to gro or ovulates (Kaneko et al., 995). In the present study also, such a trend as observed th the domnant ovulatory follcle, as evdent from the hgh concentratons of nhbn on Day-2. Such a clear trend could not be observed for the domnant non-ovulatory follcle probably because the data ere not clustered around ntaton of ave, due to non-avalablty of the follcular data. Our results shoed that plasma estradol concentratons ere maxmum durng peroestrous phase and declned durng md luteal phase hch agrees th earler reports of Batra and Pandey (982/83) and Samad et al. (988) heren the concentraton of estradol 7β follong luteolyss ncreased and reached to ts peak value ether a day before or on the day of oestrous. After attanng the peak concentraton, estradol declned thn 2 days follong estrus. Thereafter estradol fluctuates at loer levels throughout the luteal phase of the cycle except on day 4 and 0 here mnor peaks have been recorded. These mnor peaks mght have resulted from aves of follcular groth. Buffaloes have been reported to undergo to or three aves of follcular groth durng oestrous cycle th the second ave occurrng durng days 0- of the cycle (Barnsell et al., 997). The proestrous rse of estradol may be assocated th trggerng of LH release by postve feedback on hypothalamo-hypophyseal axs (Batra and Pandey, 982;983). Proestrous rse n estradol secreton after progesterone thdraal s consdered to be a prerequste event for the ntaton of both behavoral oestrous and preovulatory LH surge n most lvestock. In the present study, perpheral plasma cortsol levels ere hgh durng peroestrous phase n buffalo hch agrees th earler report of Kumar et al. (99) and Madan et al. (993). The hgh levels may be attrbuted to stress caused by ncreased physcal actvty and stress of oestrous. Plasma T 3 concentratons as maxmum durng late luteal phase hch subsequently decreased durng peroestrous phase hereas T 4 concentratons ncreased durng peroestrous phase. Vadodora et al. (978) reported a loer thyrod actvty mmedately after ovulaton th the peak actvty at the begnnng of oestrous. Hgh level of T 3 durng proestrus may possbly be due to stress caused by hyperactvty. Peak T 4 level as observed at the onset of oestrus. Ths may be due to hgh estradol level hch stmulates thyrod gland actvty by drectly actng on t th the nterventon of ptutary gland. Estrogen has been found to stmulate TSH release from ptutary gland (D Angelo and Fsher, 969) causng elevaton of T 4 durng oestrous. In concluson, the hormonal profles durng oestrous cycle presented n ths paper are more accurate and precse compared to the ndvdual studes as meta-analyss reduces the standard error by ncreasng the sample sze. ACKNOWLEDGMENTS We thank Drector, NIANP for provdng the necessary facltes to carry out the research ork. We also thank Prof. M. Venkatasamy Reddy, Department of Bostatstcs, Natonal Insttute of Mental Health and Neuro Scences, Bangalore for revsng the manuscrpt for applcaton of meta-analytcal methods. REFERENCES Arora, R. C. and R. S. Pandey Plasma concentratons of progesterone, estradol -7β and lutenzng hormone n relaton to repeat breedng n buffalo (Bubalus bubals). Anm. Prod. 34: Ahmed, A., S. P. Agaral, V. K. Agaral, S. A. Rehman and K. R. Laumas Sterod hormones. Part II. Serum progesterone concentraton n buffaloes. Ind. J. Exp. Bol. 5: Avenell, J. A., Y. Saepudn and I. C. Fletcher Concentratons of LH and progesterone n the perpheral plasma of samp buffalo co (Bubalus bubals) aroung the tme of estrus. J. Reprod. Fertl. 74: Bachalaus, N. K., R. C. Arora, A. Prasad and R. S. Pandey Plasma levels of gonadal hormones n cyclng buffalo hefers. Ind. J. Exp. Bol. 7: Barnsell, P. S., R. G. Muccolo, J. A. Vstn, W. G. Vana, R. P. Arruda, E. H. Madurera, C. A. Olvera and J. R. Molero-Flho Ovaran follcular dynamcs durng the estrous cycle n buffalo (Bubalus bubals). Therogenology 47: Batra, S. K. and R. S. Pandey. 982/83. Lutenzng hormone and estradol -7β n blood plasma and mlk durng estrous cycle and early pregnancy n Murrah buffaloes. Anm. Reprod. Sc. 5: Batra, S. K., R. C. Arora, N. K. Bachalaus and R. S. Pandey Blood and mlk progesterone n pregnant and nonpregnant buffalo. J. Dary Sc. 62: Batra, S. K., R. C. Arora, N. K. Bachalaus, G. S. Paha and R. S. Pandey Quanttatve relatonshps beteen estradol-7β n the mlk and blood of lactatng buffaloes. J. Endocrnol. 84: Burger, H. G Inhbn. Reprod. Med. Rev. :-20. Claus, R., H. Karg, D. Zauer, I. V. Butler, F. Prchner and E. Rasttenberger Analyss of factors nfluencng reproductve performance of the dary cos by progesterone assay n mlk fat. Br. Vet. J. 39: Cooper, H. and L. V. Hedges The Handbook of Research Synthess, Ne York, Russell Sage. D Angelo, S. A. and J. S. Fsher Influence of oestrogen on the ptutary-thyrod system of the female rat. Mechansm of Lactaton. Endocrne 84:7-22. Eugene, M., H. Archmede and D. Sauvant Quanttatve meta-analyss on the effects of defaunaton of the rumen on groth, ntake and dgeston n rumnants. Lvest. Prod. Sc. 85:8-9. FAOSTAT FAOSTAT Agrculture Data. Food and Agrculture Organzaton Statstcs, Rome, Italy. Avalable from: Foote, R. H., E. A. B. Oltenacu, H. L. Kmmerfeld, R. D. Smth, P. M. Rek and R. K. Braun Mlk progesterone as

6 74 Mondal et al. (200) Asan-Aust. J. Anm. Sc. 23(2):69-74 dagnostc ad. Br. Vet. J. 35: Glass, G. V Prmary, secondary and meta-analyss of research. Educaton Research 5:3-8. Gnther, O. J., L. Knopf and J. P. Kastelc Temporal assocatons among ovaran events n cattle durng oestrus cycle th to and three follcular aves. J. Reprod. Fertl. 87: Gupta, S. K. and G. S. Pope Varaton n the level of progesterone n the systemc plasma of the co. J. Endocrnol. 40:2. Hafez, E. S. E Reproducton n farm anmals, 5 th edn. Lea and Fbger, Phladelpha. Kamboj, M. and B. S. Prakash Relatonshp of progesterone n plasma and hole mlk of buffaloes durng cyclcty and early pregnancy. Trop. Anm. Health Prod. 25: Kana, Y. and H. Shmazu Changes n the plasma concentraton of lutenzng hormone, progesterone and estradol -7β durng the perovulatory perod n cyclc samp buffaloes (Bubalus bubals). Anm. Reprod. Sc. :7-24. Kaneko, H., H. Ksh, G. Watanabe, K. Taya, S. Sasamoto and Y. Hasegaa Changes n plasma concentratons of mmunoreactve nhbn, estradol and FSH assocated th follcular aves durng the estrous cycle of the co. J. Reprod. Dev. 4:3-37 Khurana, M. L. and M. L. Madan Thyrodal hormone durng estrous cycle n cattle and buffaloes. Ind. J. Dary Sc. 38:9-23. Kumar, R., R. Jndal and P. J. S. Rattan. 99. Plasma hormonal profles durng estrous cycle of Murrah buffalo hefers. Ind. J. Anm. Sc. 6(4): Madan, M. L Factors lmtng superovulaton responses n embryo transfer programme among buffaloes. Therogenology 33:280. Madan, M. L., B. S. Prakash, S. Jalkhan, S. K. Sngla, P. Palta and R. S. Mank In: Buffalo endocrnology th specal reference to embryo transfer. Embryo Botechnology Centre, NDRI, Karnal, Inda, p. 32. Mank, R. S., S. K. Sngla, P. Palta and M. L. Madan Ovaran follcular dynamcs montored by real-tme ultrasonography durng oestrous cycle n buffalo (Bubalus bubals). Asan-Aust. J. Anm. Sc. : Mares, S. E., R. G. Zmbelman and L. E. Casda Varaton n progesterone content of the bovne corpus luteum of the estrous cycle. J. Anm. Sc. 2: Mondal, S. and B. S. Prakash Comparson of luteal functon beteen cos and buffaloes durng estrous cycle. Ind. J. Dary Sc. 55(3): Mondal, S., B. S. Prakash and P. Palta. 2003a. Relatonshp beteen perpheral plasma nhbn and progesterone concentratons n Sahal cattle (Bos ndcus) and Murrah buffaloes (Bubalus bubals). Asan-Aust. J. Anm. Sc 6():6-0. Mondal, S., B. S. Prakash and P. Palta. 2003b. Perpheral plasma nhbn concentratons n relaton to expresson of estrus n Murrah buffaloes (Bubalus bubals). Ind. J. Anm. Sc. 73(4): Mondal, S. and B. S. Prakash. 2003c. Perpheral plasma progesterone concentraton n relaton to estrus expresson n Murrah buffalo (Bubalus bubals). Ind. J. Anm. Sc. 73(2): Mondal, S. and B. S. Prakash. 2003d. Perpheral plasma progesterone concentratons n relaton to expresson of estrus n Sahal cos. Ind. J. Physol. Pharmacol. 47():-4. Mondal, S., P. Palta and B. S. Prakash Influence of season on perpheral plasma progesterone n cyclng Murrah buffaloes (Bubalus bubals). Buff. J. : Mondal, S., B. S. Praksh and P. Palta. 2008a. Relatonshp beteen perpheral plasma nhbn and FSH concentratons n buffaloes (Bubalus bubals) and Sahal cos (Bos ndcus) durng estrous cycle. Trop. Anm. Health Prod. 40: Mondal, S., B. S. Prakash and P. Palta. 2008b. Perpheral plasma FSH concentratons n relaton to expresson of oestrus n Murrah buffaloes (Bubalus bubals). Buff. Bulletn 27(4): Paha, G. S. and R. S. Pandey Gonadal sterod hormone concentraton n blood plasma and mlk of prmparous and multparous pregnant and non pregnant buffaloes. Therogenology 9: Paha, G. S. and R. S. Pandey Prolactn n blood plasma and mlk of buffalo durng estrous cycle and early pregnancy. J. Dary Sc. 67: Palta, P., B. S. Prakash and M. L. Madan Perpheral nhbn levels durng estrous cycle n Murrah buffalo (Bubalus Bubals). Therogenology 45: Palta, P., S. Mondal, B. S. Prakash and M. L. Madan Perpheral plasma nhbn levels n relaton to clmatc varaton and stage of estrous cycle n buffalo (Bubalus bubals). Therogenology 47: Person, R. A. and O. J. Gnther Ultrasonc magng of the ovares and uterus n cattle. Therogenology 29:2-29. Rao, L. V. and R. S. Pandey Seasonal changes n the plasma progesterone concentraton n buffalo co (Bubalus bubals). J. Reprod. Fertl. 66:57-6. Rao, L. V. and R. S. Pandey Seasonal varatons n estradol-7β and lutenzng hormone n the blood of buffalo cos (Bubalus bubals). J. Endocrnol. 98: Samad, H. A., H. Hamd and N. V. Rehman Plasma estradol-7β concentratons durng oestrous cycle of Nl-Rav buffaloes. In: Proceedngs of th Internatonal congress on Anmal Reproducton and Artfcal Insemnaton held at Dubln, Ireland, p. 2:3. Sauvant, D., P. Schmdely, J. J. Daudn and N. R. St-Perre Meta-analyss of expermental data n anmal nutrton. Anm. 2: Sharma, K. B., S. Nayyar, V. S. Malk, R. Sngh and S. P. S. Sodh Levels of hormones and mnerals n cyclc, anestrus and subestrus buffalo hefers. Ind. J. Anm. Sc. 69(4): Schomberg, D. W., S. P. Coudert and R. V. Short Effects of bovne LH and human choronc gonadotropn on the bovne corpus luteum n vvo. J. Reprod. Fertl. 4: Taya, K., H. Kaneko, G. Watanabe and S. Sasamoto. 99. Inhbn and secreton of FSH n estrous cycles of cos and pg. J. Reprod. Fertl. (Suppl.) 43:5-62. Vadodora, V. P., K. Janakraman and N. C. Buch Thyrod actvty n relaton to reproductve performance of Surt buffalo hefers (Bubalus bubals) - proten bound odne. Ind. J. Exp. Bol. 6: