effect of gonadotropin-releasing hormone at estrus on subsequent luteal function and fertility in...

8/3/2019 Effect of Gonadotropin-releasing Hormone at Estrus on Subsequent Luteal Function and Fertility in Lactating Holstei

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GONADOTROPIN-RELEASING HORMONE DURING HEAT STRESS 1951beneficial for herds with low fertility ( S45% concep-tion rates) than for herds with conception rates>60%. liosenberg et al. ( 2 1 ) reported a n improvedresponsle when repeat breeder cows were injected withGnRH near the s tart of detected estrus followed by AI4 to 30 h later than in similarly treated cows thatwere inseminated


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1952 ULLAH ET AL.= r 1 oo

652 4 6 8 10 12 14 16 18 20 22 24Time of Day (h )

Figure 1. Mean diurnal ambient temperature ( A), relative hu-midity ( 0 ) . and temperature-humidity index ( e).

temperatures, which were above the normal rangereported for cattle ( 3 ) . For both treated cows andcontrol cows, the mean rectal tem pera ture was 39.1 fO.l"C, and the range across the experimental periodwas 38.8 f 0.1 t o 39.4 f 0.1"C.Progesterone

Serum progesterone concentrations were higher ( P< 0.05) for cows treated with GnRH than for controlcows on d 10 (5.0 f 0.9 vs. 3.4 f 0.7 ng/ml, respec-tively) and d 15 (5.7 k 1.1 vs. 3 .7 f 0.9 ng/ml,respectively) for the luteal phase following treatm entand on d 25 (4.6 +_ 1.2 vs. 2.9 f 0.9 ng/ml, respec-tively) and d 30 (6.1 _+ 0.9 vs. 2.2 k 0.6 ng/ml,respectively). Overall trea tme nt means were 5.0 k 0.9and 3.4 k 0.7 ng/ml, respectively (Figure 2). Thehigher concentrations of progesterone in the treatedcows before d 20 were likely due to the stimulatoryeffects of GnRH (1 6) . Our report is the first t o ob-serve that this stimulatory effect occurred in the cor-pus luteum, the function of which was suppressed byheat stress ( 11 . The mechanism for this stimulatoryeffect in th e corpus luteum is unknown, but Mee et al.( 1 6 ) reported tha t GnRH increased the proportion oflarge luteal cells in corpora lutea of repeat breederdairy cows removed 10 d after estrus and GnRHtreatment. The higher concentration of progesteronein the cows treated with GnRH on d 25 and 30 aftertreatment could have been due to the higher propor-tion of pregnant cows in the group o r perhaps to thelingering effects of GnRH on the corpus luteum dur-ing early gestation ( 16 ). Mean concentrations of se-rum progesterone were higher ( P < 0.05) for cowstreated with GnRH than for control cows whether ornot they were diagnosed as being pregnant.

FertilityFirst AI conception ra tes , as determined by rectal

palpation after d 45, were 28.6 and 17.9% ( P > 0.05)for the treated and control cows, respectively. For the28 cows that were monitored for progesterone, 42.8%of the cows treated with GnRH and 57.1% of thecontrol cows were determined t o be pregnant based onhigh serum progesterone concentrations (>1 ng/ml)on d 20 after estrus and AI. When palpated for preg-nancy after d 45, respective pregnancy rates were28.6 and 14.396, representing a change ( P < 0.05) inthe control cows but not in the treated cows (Figure3) . These results are consistent with those of Mee etal. (161, whose study with repeat breeder cowsresulted in 53 and 50% pregnancy rates based onprogesterone concentrations 20 to 30 d o r 20 t o 40 dafter AI, but 43 and 14% when based on palpation 42to 56 d after AI for cows treated with GnRH andsaline, respectively. I n contrast , BonDurant et al. ( 5 )reported no difference in pregnancy rate when repeatbreeder cows were treated with GnRH or saline dur-ing the summer. Progesterone concentrations werenot monitored during this study.

Because rectal tem pera tures did not differ betweenthe treatment groups and because the concentrationof luteal progesterone was increased by GnRH treat-ment, results of our experiment support the hypothe-sis that the suppression of corpus luteum functionth at has been induced by extreme heat is a factor thatcompromises embryo survival. Jerseys, which aremore tolerant of heat stress than are Holsteins, aswas indicated by higher fertility during the summer(2, 24), also have higher concentrations of luteal

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0 5 10 15 20 25 30BloodCollection (d)

Figure 2. Mean serum concentrations of progesterone in cowstreated with GnRH (m ; n = 14) r saline (0; = 14 ) ( P i .05).Journal of Dairy Science Vol. 79, No. 11 , 1996


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GONADOTROPIN-RELEASING HORMONE DURING HEAT STRESS 1953

60 -70 I0 I- ab

42.86a n0 I-bc

57.14

nGnRH Saline

Figure 3. Pregnancy rate (p erce nta ge) on the basis of rectalpalpation ( w ) , progesterone concentrations ( U) , o r both in cowstreated with GnRH ( n = 14) o r saline ( n = 14). Different letters ( a ,b ) indicate a difference ( P < 0.05).

progesterone and lower rectal temperatu res ( 7 , 12).Artificial cooling of dairy cows during the summer,which results in higher fertility (20, 26, 29), alsoresults in higher luteal progesterone (301, lower rec-tal temperatures (20, 29, 30), and improved bodycondition ( 8 ) , all of which could affect fertility.Elevated core body temperature in the periestrusperiod has a negative effect on embryo quality (4, 19)and embryo survival (1, 27). Although based onlimited observations, results of the present study sug-gest tha.t suppressed secretion of luteal progesteroneis a factor in embryo survival as well.

REFERENCES1Alliston, C. W., B. Howarth, and L. C. Ulberg. 1965. Embryonicmortality following culture in vitro of one- and two-cell rabbiteggs, a t elevated tempe ratures. J. Reprod. Fertil. 9:337.2Ba din ga, L., R. J. Collier, W. W. Thatcher, a nd C. J. Wilcox.1985. Effects of climate and managemental factors on concep-tion ra te i n dairy cattle in subtropical environments. J . Dairy

Sci. 613:78.3 Bianca, W. 1968. Thermoregulation. Page 17 in Adaptation ofDomestic Animals. E.S.E. Hafez, ed. Lea & Febiger, Philadel-phia, PA.4 Boland, M. P., and I. Gordon. 1989. Embryo transfer in develop-ing countries-Saudi Arabia. Theriogenology 31:41.

5Bo nDur ant, R. H., I. Revah, C. Fra nti, R. J. Harmon, D. Hird,D. Klungbord, M. McClosky, L. Weaver, and B. Wilgenburg.1991. Effect of gonadotropin releasing hormone on repe at-breeder California dairy cows. Theriogenology 35:365.6 Fuquay, J. W. 1981. Hea t stress as it affects animal production.J. h i m . Sci. 52:164.7Fuqua~y, . W., . T. Chapin, and W. H. Brown. 1980. Postpar-tum he at str ess in dairy cows. Int. J . Biometeorol. 24:141.8 Fuquay, J . W., M. Younas, R. V. Gonzalez, W. R. Hearne , and A.E. Smith. 1993. Productive a nd reproductive responses of dairycows to fans in a hot, humid environment. Proc. 4t h Int. Livest.Environ. Symp., Coventry, Eng land. Am. Soc. Agric. Eng., St.Joseph, MI.

gGwazdauskas, F. C., C. J . Wilcox, and W. W. Thatcher. 1975Environmental and management factors affecting conceptionrate in a subtropical environment. J . Dairy Sci. 58:88.lOHer, E., D. Wolfenson, I. Flamenbaum, Y. Folman, M. Kaim.and A. Berman. 1988. Thermal, productive, and reproductiveremonses of hieh vieldine cows exDosed t o shor t-term cooling insummer. J. Dii, Sci. f1:1085. IIlHowell. J. L.. J . W. Fuouav. and A. E. Smith. 1994. Corpusluteum growth and f u n c h i in lactating Holstein cows duringspring and summer seasons. J. Dairy Sci. 77:735.12Imtiaz Hussain, S . M., J . W. Fuquay, and M. Younas. 1992Estrous cyclicity in nonlactating and lactating Holsteins andJerseys in a Pakis tani summer. J . Dairy Sci. 75:2968.13 Johnson, D. E. 1986. Climatic stress and production efficiencyPage 17 in Limiting the Effects of Stress on Cattle. Res. Bull.512, Western Regional Res. Publ. No. 009. Utah Agric. Exp.Stn., Logan.14Lutgens , F. K. , and E . J . Tarbuck. 1982. The Atmosphere: AnIntroduction to Meteorology. Prentice-Hall, Inc., EnglewoodCliffs, NJ.15Maunder. W. J. 1970. The Value of Weather. M ethuen and Co.Ltd., London, England.16 Mee. 0. M.. J . S. tevenson.B. M. Alexander, and R. G. Sasser.1993. Administr ation of GnRH at estrus influences pregnancyrates, serum concentrations of LH, FSH, Estradiol-170,pregnancy-specific protein B. and progesterone, proportion ofluteal cell types, and in vitro production of progesterone indairy cows. J. Anim. Sci. 71:185.17 Mee, 0.M., J . S. Stevenson, and R. K. Scoby. 1990. Influence ofgonadotropin-releasing hormone and timing of inseminationrelative to estrus on pregnancy rates of dairy cattle a t firstinsemination. J . Dairy Sci. 73:1500.18Nickerson, S . C. 1987. Mastitis management under hot, humidconditions. Page 32 in Proc. Dairy Herd Management Conf.Macon, GA., Univ. Georgia, Athens.19Pu tney, D. J., S.Mullins, W. W. Thatcher, M. Drost, and T. SGross. 1989. Embryonic development in superovulated dairycattle exposed to elevated ambient tempe rature. Anim. Reprod.Sci. 19:37.20Roman-Ponce, H., W. W. Thatcher, and C. J. Wilcox. 1981Hormonal relationships and physiological responses of lactatingdairy cows to a shade management system in a subtropicalenvironment. Theriogenology 16:139.21 Rosenberg, M., S. . Chun, M. Kaim, Z. Herz, and Y. Folman.1991. The effect of GnRH administration t o dairy cows duringestrus on plasma LH and conception in relation to the time oftreatment and insemination. Anim. Reprod. Sci. 24:13.22 SAS/STAT@Users Guide. Release 6.04. 1990. SAS Inst., Inc.,Cary, NC.23 Stevenson, J . S., E. P. Call, R. K. Scoby, and A. P. P hatak. 1990Double insemination a nd gonadotropin-releasing hormonetreat ment of repeat breeding dairy cattle. J. Dairy Sci. 73:176624 Stott, G. H. 1961. Female and breed associated with seasonalfertility variation in dairy cattle. J. Dairy Sci. 44:1698.25 Stott, G. H., an d R. J. Williams. 1962. Causes of low breedingefficiency in dairy cattle associated with seasonal high temper a-tures. J . Dairy Sci. 45:1369.26Thatcher, W. W., F. C. Gwazdauskas, C. J. Wilcox, J. Toms, HH. Head, D. E. Bufing ton, and W. . Fredriksson . 1974. Milk-ing performance and reproductive efficiency of dairy cows in anenvironmentally controlled structure. J. Dairy Sci. 57:304.27 Ulberg, L. C., and P. J. Burfening. 1967. Embryo death result-ing from adverse environment on spermatozoa or ova. J. AnimSci. 26571.28 Weaver, L. D., C. A. Daley, and W. J. Goodger. 1988. Economicmodeling of th e use of gonadotropin-releasing hormone a t insemination t o improve fertility in dairy cows. JAWMA ( J .AmVet. Med. Assoc.) 12:1714.29 Wolfenson, D., I. Flamenbaum, and A. Berman. 1988. Hyperthermia and body energy store effects on estrous behavior,conceDtion rate. a nd corDus luteum function in dairy cows. J.Dairy Sci. 71:3497.30Younas, M., J . W. Fuquay, A. E. Smith , and A. B. Moore. 1993Estrous and endocrine responses of lactatin g Holsteins to forcedventilation during summer. J. Dairy Sci. 76:430.

Journal of Dairy Science Vol. 79,No. 1 1 , 1996

effect of gonadotropin-releasing hormone at estrus on subsequent luteal function and fertility in...

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