AND OVULATION IN POSTPARTUM HOLSTEIN COWS 1

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1 THE RELATNSHPS BETWEEN ENERGY BALANCE, MLK PRDUCTN AND VULATN N PSTPARTUM HLSTEN CWS 1 Summary Energy balance and serum prgesterne cncentratins were mnitred during early lactatin in a grup f high prducing Hlstein cws. The pstpartum interval t nrmal vulatin averaged days (range 6 t 83 days). Average energy balance during the first 20 days f lactatin (cumulative daily calculated energy balance divided by days in milk) was inversely related t days t nrmal vulatin (r = -.60) and t milk prductin (r = -.80). Milk yield during this perid was nt clsely related t days.t vulatin (r =.30). Milk yield was als nt significantly related t serum prlactin cncentratins ver the first 12 weeks f lactatin (r =.27). During early lactatin, energy balance was maximally negative until peak milk yield and then began returning tward zer, with the magnitude and duratin f negative energy balance being quite variable. n the average, vulatin and the initiatin f the first nrmal luteal phase ccurred apprximately 10 days after energy balance began returning tward zer. During this 10-day interval, a transient elevatin in serum prgesterne cncentratins ccurred in eight f 13 cws. These results suggest that energy balance during the first 20 days f lactatin is imprtant in determining the nset f varian activity fllwing parturitign. (Key Wrds: Energy Balance, vulatin, Lactatin.) W. R. Butler 2, R. W. Everett 2 and C. E. Cppck 3 Crnell University, thaca, NY The authrs express appreciatin t G. Lake and F. Michel, fr technical assistance, and t Mrs. Lrraine Taylr, fr the preparatin f this manuscript. We als thank James R. Harner and the staff f the Crnell Animal Science Teaching and Research Center fr caring fr the experimental animals. Purified vine prlactin was kindly supplied by Dr. L. E. Reichert, Jr., and NH-P-B4 was prvided by NAMDD. 2 Dept. f Anim. Sci. 3 Dept. f Anim. Sci., Texas A&M Univ., Cllege Statin ntrductin The interval frm parturitin t first vulatin in dairy cattle is related t the level f milk Prductin (Marin and Gier, 1968; Stevensn and Britt, 1979) and is lnger in cws with a higher genetic ptential fr milk yield (Whitmre et al., 1974). Because high prducing cws cannt maintain a psitive energy balance during the early lactatin and must mbilize bdy reserves (Cppck et al., 1974), it is nt surprising that pstpartum varian activity was mre clsely assciated with milk prductin than with ttal digestible nutrient intake (Whitmre et al., 1974). Thus, it seems lgical that the interval t first vulatin is related t energy balance. The nature f this relatinship has nt been established and is the subject f the present study. Experimental Prcedure The 13 Hlstein cws used in this study calved in September, were in their secnd (n = 9), third (n = 3) r fifth (n = 1) lactatin and were randmly selected frm acrss diet grups frm a larger nutritin trial n prtein utilizatin. The husing, management and diet have been described previusly (Kwan et al., 1977). Briefly, milk yield was recrded at each milking. All cws were fed a cntrl diet (16.6% crude prtein, CP) fr 4 weeks pstpartum and were then assigned t grups and fed diets cntaining 11.7 t 16.6% CP. Diets cnsisted f cmmercially prepared cncentrates mixed with crn silage (FN ) and chpped alfalfa hay (FN ). The rati f cncentrate t frage was the same fr all diets: 60% cncentrate, 20% crn silage and 20% alfalfa hay n a dry basis. Frage dry matter was determined twice weekly, and, if necessary, adjustments were made t maintain the desired rati f frages t cncentrates. Feed ffered and rts were recrded daily, while feed samples were cllected twice weekly fr labratry analysis f dry matter, N and fiber. Feed, rts, 742 JURNAL F ANMAL SCENCE, Vl. 53, N. 3, 1981

2 ENERGY BALANCE AND VULATN 743 milk, feces and urine were cllected frm 40 cws frm the riginal study, and grss energy measured fr calculatin f energy balance. A detailed descriptin f dietary ingredients, chemical cmpsitin and digestibility f each diet was prvided by Kwan et al. (1977). Bld was cllected 1 hr befre the nn milking n alternate days fr 12 weeks after parturitin; samples were taken frm the cccygeal vein r artery r frm the mammary vein. The bld was allwed t clt at rm temperature and then refrigerated vernight befre centrifugatin. Serum samples were stred at -20 C prir t radiimmunassay fr prgesterne (Gengenbach et al., 1978), prlactin (Fx et al., 1981) and luteinizing hrmne (LH; Niswender et al., 1969). The perfrmance f these assays was mnitred by the calculatin f cefficients f variatin (CV) fr three vlumes f pled serum samples in each assay. The within- and between-assay CV were 6 and 8% (n = 4), respectively, fr prlactin; 7 and 10% (n = 7) fr prgesterne, and 5 and 8% (n = 2) fr LH. With a sample vlume f 100 /~1, the lwer limits f sensitivity (g90% relative binding) f the prlactin and prgesterne radiimmunassays were 2 ng/ml (NH-P-B4) and.3 ng/ml, respectively. LH cncentratins were measured in 200-/al serum aliquts with a lwer limit f sensitivity f.25 ng/ml fr the standard (NH-LH-B9). All animals were given a rutine health examinatin 3 t 4 weeks pstpartum which included palpatin f the reprductive tract. nly nrmal healthy cws withut pstpartum cmplicatins were included in the study. Nrmal vulatin was assumed t have ccurred if serum prgesterne cncentratins increased abve.5 ng/ml fr mre than 10 days and exceeded 2.0 ng/ml in at least tw successive samples (cllected n alternate days) during this perid. The day f vulatin was assumed t be 3 t 4 days befre an increase in serum prgesterne t />1 ng/ml (Stevensn and Britt, 1980). ncreases in serum prgesterne cncentratins nt meeting these arbitrary criteria were presumed t represent luteinizatin f an varian structure and nt necessarily vulatin. Estrus behavir was TABLE 1. PSTPARTUM NTERVAL T VULATN AND MLK YELD F CWS WTHN DETARY PRTEN GRUPS 305- nterval day pstpartum milk Diet Cw t vulatin, yield, grup a number days kg , ,042 Mean , , , , , ,708 Mean , , ,788 Mean , , , , ,131 Mean ,386 aall cws received the same cmplete diet (16.6% crude prtein) fr 4 weeks pstpartum. Beginning in week 5, crude prtein in the diets was adjusted t: (1) 11.7%; (2) 13.9%; (3) 16.6% and (4) 16.6%.

3 744 BUTLER ET AL. nted in assciatin with the first vulatin in seven (54%) f the cws. Data were summarized weekly fr individual cw feed intake, feed dry matter, bdy weight, milk weight and milk cmpsitin. Daily means fr digestible and net energy fr lactatin were cmputed fr each cw. Calculated energy balance fr each day f lactatin was cmputed as net energy fr lactatin (NE,) cnsumed minus NE~ required. The actual energy value fr feeds was taken frm the digestin trials. The NE, requirements were cmputed n the basis f NRC (1978) guidelines in which NE~ fr maintenance is calculated as metablic bdy size (MBS = BW "Ts) X.080. The maintenance requirement was increased by 20 and 10% fr cws in lactatins 1 and 2. The NE~ lactatin requirement was cmputed as 15.0 x milk fat +.4 x milk weight x.74 (NRC, 1978). Data n daily milk yield and energy balance were subjected t least-squares linear regressin analysis, with number f days pstpartum t vulatin as the dependent variable. Average energy balance fr each day f lactatin was calculated as cumulative daily calculated energy balance divided by days in milk. Results The interval frm parturitin t nrmal vulatin averaged days (range f 6 t 83 days) and seemed unrelated t dietary prtein (table 1). Fr cws used in the present study, milk yield within dietary grups was similar (table 1). The relatinships between milk prductin, energy balance and serum prgesterne and LH cncentratins near the time f first vulatin are summarized in table 2. n eight f 13 cws, nrmal vulatin was preceded by a transient elevatin in serum prgesterne cncentratin. The variatin in magnitude (.7 t 1.9 ng/ml) and duratin (4 t 11 days) f these transient elevatins was such that average serum prgesterne cncentratins fr the grup were nt significantly increased befre vulatin. Fllwing vulatin, a characteristic luteal phase prgesterne pattern was bserved. Serum LH cncentratins were similar befre and after vulatin. During the first few weeks f lactatin, energy balance became negative in all f the cws as milk prductin rapidly increased, but magnitude f negative energy balance (maximum f-32 Meal/day) and duratin (range 4 t 14 weeks) were quite variable9 Peak milk yields in individual cws ccurred between weeks 4 and 7 f Z < Z z m z~,.~ z < [.., 8r. ~ m[,-, m z~u,.-1.1 e~ < +1 +J +l +1 ~q ~ j 9 -t ~1 ~t.: 8 E t~ e~ e~.

4 ENERGY BALANCE AND VULATN 745 TABLE 3. CRRELATNS a BETWEEN AVERAGE ENERGY BALANCE (AVG EB), PSTPARTUM DAYS T VULATN (DT) AND DALY MLK YELD Days in milk J, tem Avg. EB vs DT Milk yield vs Avg. EB Milk yield vs DT a5% level f significance fr r =.55. lactatin. n the average, first vulatin ccurred apprximately 10 days after maximal negative energy balance and during peak lactatin. At vulatin, energy balance was still negative, but was returning tward zer (table 2). Regressin analysis did nt shw a significant relatinship between number f days t vulatin and calculated energy balance at vulatin (r = -.07) r during the preceding week (r =.25). Hwever, further analyses revealed a significant negative crrelatin between average energy balance and number f days t vulatin (table 3). By 20 days in milk, the crrelatin (r = -.60) was significant; the data are shwn graphically in figure 1. As the energy deficit incurred during the perid increased, the interval t first vulatin became lnger. Average milk yield fr the first 20 days was highly crrelated t average energy balance (r = -.80), as shwn in figure 2, but was nt clsely related t the pstpartum interval t vulatin (r =.30). As lactatin prgressed, milk yield became mre highly crrelated t days t vulatin, with the crrelatin highest at 60 days f lactatin (table 3). This was after peak milk yield and first vulatin in mst animals. The verall relatinship between milk yield and calculated energy balance during early lactatin is shwn in figure 3. Energy balance remained highly negative until peak lactatin, after which it mved prgressively tward zer as milk prductin declined. Average milk prductin fr the 305-day lactatin in these animals was 7, kilgrams. verall, serum prlactin cncentratins were nt clsely related t milk yield. Althugh mean serum prlactin cncentratins (figure 3) shwed a pattern similar t that bserved fr average milk yield, the crrelatin between prlactin cncen- tratins and milk yield fr individual sampling days was lw (r =.27), and even lwer during the week f peak lactatin (r =.13). Discussin The interval frm parturitin t first nrmal vulatin in a grup f high prducing dairy cws was inversely related t average energy balance during the first 20 days f lactatin: the greater the average energy deficit incurred, the lnger the delay t vulatin. Since energy balance is a functin f nutrient intake versus requirements (milk prductin plus maintenance), the present data are cnsistent with reprted detrimental effects f undernutritin (Wagner and xenreider, 1971; Flman et al., 1973) and lw bld glucse cncentratins (Patil and Deshpande, 1979) n pstpartum varian activity. Milk prductin was reprted t be directly related t days t first vulatin !..!!!! Y = X 0 9 9, 9! AVG ENERGY BALANCE (Meal/Day) Figure 1. Relatinship between average energy balance during the first 20 days f lactatin and number f days pstpartum t vulatin in dairy cws.

5 746 BUTLER ET AL. Z u "- 25 Q. >,< 20, ~ AVG ENERGY BALANCE (Meal/Day) Figure 2. Relatinship between average energy balance and average milk prductin during the first 20 days f lactatin in dairy cws. (Jrdan and Swansn, 1979; Stevensn and Britt, 1979) and appears t be mre clsely crrelated t that interval than is energy (TDN) intake (Whitmre et al., 1974). The clser relatinship with milk yield apparently results frm the fact that, althugh milk yield and energy balance are highly crrelated during early lactatin, individual cws meet the energy demands thrugh different cmbinatins f changes in feed intake and mbilizatin f bdy reserves. Bdy weight changes per se are nt highly crrelated t pstpartum varian functin (xenreider and Wagner, 1971; Flman et al., 1973; Patil and Deshpande, 1979; Stevensn and Britt, 1979), nr t energy balance in the early pstpartum cw (Flatt, 1966). n the present study, differences in dietary prtein after the first mnth f lactatin did nt appear t influence the interval t vulatin. ne-half f the animals had vulated befre dietary adjustments. n additin t average energy balance, relative changes in energy balance may als be related t the timing f vulatin. n the average, vulatin ccurred within 10 days after negative energy balance was maximal and had begun returning tward zer. Mst cws vulated while still in negative energy balance, but energy balance values varied amng animals and were nt significantly crrelated t the interval t vulatin. Cincident with the beginning f recvery frm negative energy balance was a transient elevatin in serum prgesterne cncentratins. Similar elevatins in pr- gesterne befre first vulatin have als been bserved in lactating beef cws (Dnaldsn et al., 1970; Prybil and Butler, 1978; Williams and Ray, 1980). n lactating dairy cws, such transient increases in plasma prgesterne are reprtedly preceded by small LH surges (Lamming, 1978; Schams et al., 1978) and are assciated with the initiatin f pstpartum varian activity (Dbsn, 1978). Lamming (1978) suggested "the mechanism respnsible fr initiating the first LH surge which precedes the first prgesterne secretin is still nt clear and seems t hld the key t early varian activity in the lactating cw." Early fllicular develpment and estrgen prductin are imprtant predictrs f first vulatin in cws (Stevensn and Britt, 1980) and may ccur in respnse t activatin f the hypthalam-hypphyseal axis cntrlling tnic LH secretin. Small, episdic releases f LH begin 1 t 2 weeks pstpartum, but a psitive assciatin f this pulsatile LH pattern with the nset f varian activity has nt been established unequivcally (Lamming, 1978; Stevensn and Britt, 1979). The present results suggest that energy balance may als be imprtant in determining the timing f the events leading t first nrmal vulatin. Althugh the mst likely mechanism fr such an effect wuld seem t invlve regulatin f LH secretin, a direct casual relatinship cannt be established frm the present study, in which bld samples were taken fairly infrequently (Lamming, 1978; Schams et al., 1978; Steven- ~ 3 t!!! PEAK MLK J YELD n=13 i WEEKS Figure 3. Milk prductin, energy balance and serum prlactin (PRL) cncentratins during early lactatin in dairy cws. The data have been nrmalized t peak milk yield. Peak milk yield ccurred at 4 weeks f lactatin in three cws; these data were nt included in the calculatin f mean values fr -5 and -4 weeks.

6 ENERGY BALANCE AND VULATN 747 sn and Britt, 1979), and further study is needed. The crrelatin between serum prlactin befre milking and milk yield ver the curse f lactatin has been fund t be very lw (Kprwski and Tucker, 1973). n the present study, samples were cllected mre frequently during early lactatin, but a similar lw crrelatin was bserved. Fertility in the lactating dairy cw, as measured by number f days t first inseminatin and cnceptin rate, is inversely related t milk prductin (Spalding et al., 1975). nasmuch as an increase in the number f estrus cycles befre 60 days pstpartum is related t decreased services per cnceptin during the breeding perid after 60 days (Thatcher and Wilcx, 1973), maintenance f high herd milk prductin withut a crrespnding reductin in reprductive perfrmance wuld be facilitated by a shrt pstpartum interval t vulatin. The present results indicate that negative energy balance, which reflects the metablic demands f lactatin, may be very imprtant in determining the length f this interval. t is well accepted that milking r the suckling stimulus als inhibits vulatin (Casida, 1971; England et al., 1973; Radfrd et al., 1978; Carruthers and Hafs, 1980). t has been prpsed that these varius inhibitry effects n varian activity may be mediated via alteratins in LH secretin (Radfrd et al., 1978; Carruthers and Hafs, 1980; Stevensn and Britt, 1980), but it is nt clear whether the mechanisms invlved affect the tnic r surge mdes f LH secretin, r bth. Literature Cited Carruthers, T. D. and H. D. Hafs Suckling and fur-times daily milking: nfluence n vulatin, estrus and serum luteinizing hrmne, gluccrticids and prlactin in pstpartum Hlsteins. J. Anita. Sci. 50:919. Casida, L. E The pstpartum interval and its relatin t fertility in the cw, sw and ewe. J. Anim. Sci. 32 (Suppl. ):66. Cppck, C. E., C. H. Nller and S. A. Wlfe Effect f frage-cncentrate rati in cmplete feeds fed ad libitum n energy intake in relatin t requirements by dairy cws. J. Dairy Sci. 57: Dbsn, H Radiimmunassay f FSH in the plasma f pst-partum dairy cws. J. Reprd. Fertil. 52:45. Dnaldsn, L. E., J. M. Bassett and G. D. Thrburn Peripheral plasma prgesterne cncentratin f cws during puberty, estrus cycles, pregnancy and lactatin, and the effects f under- nutritin r exgenus cytcin n prgesterne cncentratin. J. Endcrinl. 48:599. England, B. G., E. R. Hauser and L. E. Casida Sme effects f unilateral variectmy in the pstpartum beef cw. J. Anita. Sci. 36:45. Flatt, W. P Energy metablism results with lactating dairy cws. J. Dairy Sci. 49~230. Flman, Y., M. Rsenberg, Z. Herz and M. Davidsn The relatinship between plasma prgesterne cncentratin and cnceptin in pstpartum dairy cws maintained n tw levels f nutritin. J. Reprd. Fertil. 34:267. Fx, L., W. R. Butler, R, W. Everett and R. P. Natzke Effect f adrencrticptrpin n milk and plasma crtisl and prlactin cncentratins. J. Dairy Sci. 64:1794. Gengenbach, D. R., N. Butendieck, P. M. Riek, R. L. Scipini, E. B. ltenacu and R. H. Fte Cntrlled supervulatin in dairy heifers using prstaglandin F2a and pregnant mare serum gnadtrpin. J. Anim. Sci. 46:1293. Jrdan, E. R. and L. V. Swansn Effect f crude prtein n reprductive efficiency, serum ttal prtein and albumin in the high-prducing dairy cw. J. Dairy Sci. 62:58. Kprwski, J. A. and H. A. Tucker Serum prlaetin during varius physilgical states and its relatinship t milk prductin in the bvine. Endcrinlgy 92 : Kwan, K., C. E. Cppck, G. B. Lake, M. J. Fettman, L. E. Chase and R. E. McDwell Use f urea by early pstpartum Hlstein cws. J. Dairy Sci. 60:1706. Lamming, G. E Reprductin during lactatin. P n D. B. Crightn (Ed.) Cntrl f vulatin. Butterwrths, Lndn. Marin, G. B. and H. T. Gier Factrs affecting bvine varian activity after parturitin. J. Anim. Sci. 27:1621. NRC Nutrient Requirements f Dmestic Animals, N. 3. Nutrient Requirements f Dairy Cattle. Fifth Revised Ed. Natinal Academy f Sciences-Natinal Research Cuncil, Washingtn, DC. Niswender, G. D., L. E. Reichert, A. R. Midgley and A. V. Nalbandv Radiimmunassay fr bvine and vine luteinizing hrmne. Endcrinlgy 84:1166. xenreider, S. L. and W. C. Wagner Effect f lactatin and energy intake n pstpartum varian activity in the cw. J. Anim. Sci. 33: Patil, J. S. and B. R. Deshpande Changes in bdy weight, bld glucse and serum prteins in relatin t the appearance f pst-partum estrus in Gir cws. J. Reprd. Fertit. 57:525. Prybil, M. K. and W. R. Butler The relatinship between prgesterne secretin and the initiatin f vulatin in pstpartum beef cws. J. Anim. Sci. 47 (Suppl. 1):383. Radfrd, H. M., C. D. Nancarrw and P. E. Mattner varian functin in suckling and nnsuckling beef cws pst partum. J. Reprd. Fertil. 54:49. Schams, D., E. Schalenberger, C. Menzer, J. Stangl, K. Zttmeier, B. Hffman and H. Karg Prfiles f LH, FSH and prgesterne in pst-

7 748 BUTLER ET AL. partum dairy cws and their relatinships t the cmmencement f cyclic functins. Therigenlg)' 10:453. Spalding, R. W., R. W. Everett and R. H. Fte Fertility in New Yrk artificially inseminated Hlstein herds in dairy herd imprvement. J. Dairy Sei. 58:718. Stevensn, J. S. and J. H. Britt. 1979, Relatinships amng luteinizing hrmne, estradil, prgesterne, gluccrticids, milk yield, bdy weight and pstpartum varian activity in Hlstein cws. J. Dairy Sci. 48:570. Stevensn, J. S. and J. H. Britt Mdels fr predictin f days t first vulatin based n changes in endcrine and nnendcrine traits during the first tw weeks pstpartum in Hlstein cws. J. Anita. Sci. 50:103. Thatcher, W. W. and C. J. Wilcx Pstpartum estrus as an indicatr f reprductive status in the dairy cw. J. Dairy Sci. 56:608. Wagner, W. C. and S. L. xenreider Endcrine physilgy fllwing parturitin. J. Anita. Sci. 32 (Suppl. ):1. Whitmre, H. L., W. J. Tyler and L. E. Casida Effects f early pstpartum breeding in dairy cattle, J. Anirn. Sci. 38:339. Williams, G. L. and D. E. Ray Hrmnal and reprductive prfiles f early pstpartum beef heifers after prlactin suppressin r steridinduced luteal functin. J. Anita. Sci. 50:906.