Effect of amount of undegradable crude protein in the diets of high-yielding dairy cows on energy balance and reproduction

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1 Livestock Production Science 63 (2000) locte/ livprodsci Effect of mount of undegrdle crude protein in the diets of high-yielding diry cows on energy lnce nd reproduction, I. Bruckentl *, M. Holtzmn, M. Kim, Y. Ahroni, S. Zmwell, H. Voet, A. Arieli Institute of Animl Science, Agriculturl Reserch Orgniztion, The Volcni Center, P.O. Box 6, Bet Dgn 50250, Isrel Deprtment of Animl Science, The Herew University of Jeruslem, Fculty of Agriculturl, Food nd Environmentl Sciences, Rehovot 76100, Isrel Received 23 Decemer 1998; received in revised form 22 April 1999; ccepted 10 My 1999 Astrct This tril ws designed to investigte effects of the mount of dietry undegrdle crude protein (CP) nd the rtio of degrdle orgnic mtter to degrdle CP in the diets of high-yielding diry cows on milk yield, energy lnce nd fertility during the first three months postprtum. Forty-five Isreli Holstein cows were ssigned to three dietry tretments t 2 d postprtum. Dietry tretments were (1) 16.7% CP, of which 32% ws undegrdle (control); (2) 16.7% CP, of which 38% ws undegrdle; nd (3) 18.0% CP, of which 35% ws undegrdle. Corn gluten mel (CGM) ws dded to diets 2 nd 3 in order to increse undegrdility. Cows were fed in groups, nd diets were offered s totl mixed rtion. Intkes of dry mtter (DMI) nd CP (kg/d) were 23.8 nd 3.975, 21.4 nd 3.574, nd 20.4 nd 3.672, for cows on diets 1, 2 nd 3, respectively. No significnt differences mong the three tretments were found for milk yield, milk protein concentrtion, milk ft, or protein nd lctose yields. Control cows lost 35.0 kg of ody weight (BW) during the first 27.2 d postprtum, nd then strted gining weight. At pproximtely dy 70 the control cows ttined their clving weight. Cows on diets 2 nd 3 lost 55 kg of BW during 45 d postprtum nd, y the end of the tril, these cows still hd not ttined their clving weight. Chnge in ody condition score (BCS) during the experimentl period reveled the sme trends. Men concentrtions (mg/100 ml) of mmoni N in ruminl fluids nd concentrtions of plsm ure N were 14.0 nd 20.3, 12.7 nd 21.2, nd 14.7 nd 21.3 for cows on diets 1, 2 nd 3, respectively. No significnt differences mong tretments were detected for ny reproduction prmeter. It ws concluded tht the differences etween control cows nd cows on diets 2 nd 3 in DMI, BW nd BCS during the first period postprtum cnnot e ttriuted to the level of dietry undegrdle CP only ut to more specific effect of CGM Elsevier Science B.V. All rights reserved. Keywords: Diry cows; Gluten mel; Undegrdle CP; Energy lnce; Insulin 1. Introduction *Corresponding uthor. Tel.: ; fx: E-mil ddress: rucken@gri.huji.c.il (I. Bruckentl) Fertility in high-producing diry herds hs een decresing in recent decdes. This phenomenon is / 00/ $ see front mtter 2000 Elsevier Science B.V. All rights reserved. PII: S (99)

2 132 I. Bruckentl et l. / Livestock Production Science 63 (2000) ovious in the Isreli herd (Ron et l., 1984) s well numer, milk yield during the previous lcttion nd s in other countries (Lmming, 1998). Butler nd ody weight (BW). The cows were mintined in the Smith (1989) found negtive correltion etween tril for t lest three months. Cows were milked milk yield nd conception rte. Ostergrd et l. three times dily, t 06:00, 14:00 nd, 20:00 h. Milk (1990) hve suggested tht the genetic reeding yield nd BW were recorded t ech milking y the progrm of diry herd is focused on high milk Afimilk system (S.A.E. AFIKIM, Kiutz Afikim, yields only, without prllel concern for incresed Isrel). Body condition ws scored once week. feed consumption. As result, the prtitioning of Milk smples from three consecutive milkings were sored metolites ws directed primrily towrd collected every 10 dys nd nlyzed for ft, protein milk yield, nd deficiency, minly of energy, ws nd lctose y the infrred procedure t the Isrel developed in other essentil metolic pthwys Cttle Assocition Lortories (Bitn Ahron, Is- (Neel nd McGillrd, 1993). rel). Sixty dys fter the eginning of the experi- Diry cows ovulte even if they re in negtive ment, ruminl fluid nd jugulr lood smples were energy lnce. However, ovrin ctivity is ppr- tken from ll cows. Rumen smples were tken ent erlier in cows with n improved energy sttus with stomch tue. Smpling ws done efore the (Stples et l., 1990). Skln et l. (1991) improved first morning mel nd 4 nd 8 h lter. Ruminl fluid the fertility of high-yielding cows y offering diets smples were kept in tues contining 0.2 ml mersupplemented with clcium sops of ftty cids. cury chloride. Similr diets in other studies (Crroll et l., 1990; Spicer et l., 1993) filed to improve fertility. The 2.2. Diets exmintion of dietry ingredients such s protein source nd concentrtion would pper to e desir- Diets were formulted to contin 30% forge on le if the im is ultimtely to improve feed intke DM sis nd differed minly in dietry CP nd (Dhimn nd Stter, 1993). The effect of dietry UDCP contents (Tle 1). Diet 1 the control diet, protein on feed intke is explined prtilly y the contined 167 g/ kg CP, of which 320 g/ kg ws effect of protein on microil fermenttion nd UDCP. Diet 2 contined 167 g/ kg CP, of which 380 digestion nd y the effect of the mino cid profile g/kg ws UDCP. Diet 3 contined 180 g/kg CP, of on whole niml metolism nd yield (Grnsworthy which 350 g/kg ws UDCP. The UDCP content of nd Cole, 1990). However, there is still lck of diet 3 ws the sme s tht of diet 2, nd the rumen informtion regrding composition nd mount of degrdle CP (RDCP) content ws the sme s in supplementry crude protein (CP). the control diet. Corn gluten mel ws dded to diets According to the NRC (1989), undegrdle (UD) 2 nd 3 in order to increse undegrdility. Ruminl CP levels in lctting cow diets rnges etween 54 degrdilities of orgnic mtter (OM) nd CP nd 63 g/kg DM. The present work ws designed to contents of the dietry ingredients, s ssessed y the determine the effect of improved protein vilility, dcron g technique (Ørskov nd McDonld, vi the higher UDCP concentrtions, on dry mtter 1979), re presented in Tle 2. When ingredient intke (DMI), milk yield, energy lnce nd fertili- dditivity of ruminl degrdtion is ssumed, the ty of high-yielding diry cows during the first three resultnt rtios of ruminlly degrdle OM to months postprtum. RDCP in diets 1, 2 nd 3 were 4.5, 5.1 nd 4.5, respectively. Cows were group fed. The diets were fed s 2. Mterils nd methods TMR t 10:00 h for d liitum intke. The feed ws moved close to the cows three times dy. Dily 2.1. Animls DM offered of ech group nd feed refused were recorded. Diets were smpled once weekly nd orts Forty-five Isreli Holstein cows (prity $ 2) were were smpled dily; representtive smple of orts ssigned to three dietry tretments t 2 d post- ws nlyzed for DM, CP nd neutrl-detergent fier prtum, ccording to expected clving dte, prity (NDF).

3 I. Bruckentl et l. / Livestock Production Science 63 (2000) Tle Reproductive mngement Ingredients of experimentl diets Ingredients (g/ kg DM) d Diet The cows were exmined y veterinrin during the first week fter clving. Following this exmin tion, cows tht were dignosed to hve retined Corn gluten mel NPN mix plcent, metritis, or other helth prolems were Milo grin given pproprite medicl tretment. Blood for pro- Brley grin gesterone nlysis ws smpled three times weekly, Whet grin strting 3 d postprtum nd continuing until first Corn grin insemintion. First postprtum ovultion ws defined Whet rn Soyen mel s the first dy fter clving when plsm progester- Rpeseed mel one concentrtion reched t lest 1 ng/ml. Estrus Whole cottonseeds detection ws performed y n utomted pedometer Citrus pulp system (S.A.E. AFIKIM) nd y visul oservtion Whet silge during two 30-min periods dily, t 09:00 nd 15:00 Corn silge Vetch hy h. Insemintion ws commenced 60 d fter clving. Ot hy Cows were inseminted t 11:00 h. Pregnncy ws Oil dignosed 45 d following insemintion y rectl CCO NCl plption. c Vitmins nd minerls Contined 60% of CP Chemicl nlyses Non-protein nitrogen. Contined (g/kg) 500 ground milo grin, 333 ure nd 167 (NH ) SO. Clculted to supply 1270 Chemicl nlyses were performed on dry feed g/kg of CP. smples tht hd een ground using 2-mm mill. c 6 6 Contined 16? 10 IU of vitmin A, 3.2? 10 IU of vitmin D, Dry mtter ws ssyed fter smples were dried t 6 16? 10 IU of vitmin E, 48 g of Mo, 48 g of Zn, 48 g of Fe, C for 12 h; corn silge nd citrus pulp were first g of Cu, 3.4 g of I, 0.32 g of Co nd 0.48 g of Se. dried t 608C for 48 h. OM ws determined fter No. 1, 16.7% dietry CP, of which 32% ws undegrdle (control); No. 2, 16.7% CP, of which 38% ws undegrdle; nd shing t 6008C for 2 h. Crude protein ws nlysed No. 3, 18.0% CP, of which 35% ws undegrdle. using Kjeldhl utonlyser (Tector, Hogns, Sweden). The NDF content ws determined ccording to the method of Vn Soest et l. (1991). In situ degrdilities of OM nd CP in dietry feeds nd the kinetics of their degrdtion in the rumen were Tle 2 determined following the method of Ørskov nd Chemicl composition (g/ kg of DM) of experimentl diets McDonld (1979) nd s descried y Arieli et l. Diet (1989). The frctionl rte of prticulte outflow from the rumen ws ssumed to e 6.5%/h. Voltile ftty cids (VFAs) in ruminl fluid tht hd een OM CP centrifuged were ssessed y gs liquid chromtog UDCP rphy (Model 5890; Hewlett-Pckrd, Avondle, PA, RDCP USA) on 0.3% Crovx 20M with 0.1% phosphoric RDOM cid (Supelco, Bellefonte, PA, USA), nd mmoni NDF ws determined y the phenol procedure (Tgri, Ether extrct NE (Mcl/ kg) ). Blood ws centrifuged, nd the plsm ws L RDOM/ RDCP seprted nd nlyzed for ure (Tgri, 1969). UDCP 5 Undegrdle CP; RDCP 5 rumen degrdle CP; Glucose ws determined y Beckmn Glucose RDOM 5 rumen degrdle OM. Anlyzer 2 (Fullerton, CA, USA), nd plsm insulin See footnote d in Tle 1. nd plsm progesterone were determined using

4 134 I. Bruckentl et l. / Livestock Production Science 63 (2000) rdioimmunossy kits (Dignostic Products, Los 21.4 nd 20.4 kg/ d, respectively. Accordingly, net Angeles, CA, USA). energy (NE) intke of the control cows nd cows fed diets 2 nd 3 ws 40.9, 36.8 nd 35.1 Mcl/ d, 2.5. Clcultions nd sttisticl nlyses respectively. Crude protein nd UCP intkes of control cows nd of cows fed diets 2 nd 3 were 4.0 Dt were sttisticlly nlysed using the GLM nd 1.2, 3.6 nd 1.4, nd 3.7 nd 1.3 kg/ d, respecprocedure of SAS (1985) to exmine the effect of tively. No significnt differences mong the three cow, prity numer, milk yield during previous diets were found for milk yield nd milk ft, protein lcttion, BW nd tretment on performnce prme- nd lctose concentrtions or yields (Tle 3). Milk ters. Comprison etween control nd CGM-sup- yield curves re descried in Fig. 1. Dt for BW plemented diets (1 vs. 2 nd 3) ws tested using nd ody condition score (BCS) re presented in nonorthogonl contrst. Averges of NH3 N nd Tle 4, nd chnges in BW nd BCS of cows VFAs in ruminl fluids nd of ure N in plsm for during the tril period re descried in Fig. 1 nd c, smples tken efore the first morning mel nd 4 respectively. The control cows lost 35.0 kg during nd 8 h lter, were used for compring the effect of the first 27.2 d (1.29 kg/ d) postprtum, nd then diet. The repeted mesures nlysis of vrince strted gining weight. By pproximtely dy 70 (ANOVA) ws used for these metolites. Reproduc- these cows ttined their clving weight. Cows fed tive prmeters were compred y t test. Sttisticl diet 2 lost 54.0 kg of BW during 44.8 d (1.21 kg/d) difference ws determined t P, postprtum, nd y the end of the tril the cows still hd not ttined their clving weight. Cows fed diet 3 lost 55.0 kg BW during 44.4 d (1.24 kg/d; P, 3. Results 0.164) nd, y the end of the tril these cows still hd not ttined their clving weight. Chnges in Men feed consumption nd milk yield nd com- BCS during the tril period expressed the sme trend position re given in Tle 3. Men DMI of the s BW (Tle 4). control cows nd cows fed diets 2 nd 3 were 23.8, Men mmoni N concentrtions in ruminl fluids Tle 3 Men feed consumption nd lest-squres mens of milk yield nd composition during 90 d of the tril period c Diet SD P. F Contrst vs DMI (kg/ d) CP intke (kg/ d) RDCP intke (kg/ d) UDCP intke (kg/ d) NEl intke (Mcl/ d) Milk yield (kg/ d) Milk ft: % Kg/ d Milk protein: % Kg/ d Milk lctose: % Kg/ d Milk energy (Mcl/ d) RDCP 5 Degrdle CP; UDCP 5 undegrdle CP. Milk energy ws clculted ccording to Tyrrel nd Reid (1965). c See footnote d in Tle 1.

5 I. Bruckentl et l. / Livestock Production Science 63 (2000) Fig. 1. Curves of milk yield () nd chnges in BW () nd ody condition score (BCS; c) of cows fed the control diet No. 1 (d), the diet contining 16.7% dietry CP, No. 2 (38% of which ws undegrdle; h), nd the diet contining 18.0% dietry CP No. 3 (35% of which ws undegrdle; n) throughout the tril.

6 136 I. Bruckentl et l. / Livestock Production Science 63 (2000) Tle 4 Lest-squres mens for odyweight (BW) nd ody condition score (BCS) during 90 d of the tril period c Diet SD P. F Contrst 1 vs Initil BW (kg) Miniml BW (kg) Dys to miniml BW BW loss (kg) BW 90 d postprtum Initil BCS Miniml BCS Dys to miniml BCS BCS 90 d postprtum BW nd BCS 2 d postprtum. Lst dy on which miniml BW or BCS ws recorded. c See footnote d in Tle 1. Tle 5 were 14.0, 12.7 nd 14.7 mg/ 100 ml for control Lest-squre mens of mmoni N in ruminl fluid, ure N in cows nd cows fed diets 2 nd 3, respectively (P, plsm, totl VFAs in ruminl fluid, nd the reltive concentrtion 0.04; Tle 5). Men plsm ure N concentrtions of the individul VFAs were 20.3, 21.2 nd 21.3 mg/ 100 ml for control 1 Diet S.E.M. P. F cows nd cows fed diets 2 nd 3, respectively (P, ; Tle 5). NH N (mg/100 ml) Totl men VFA concentrtions in ruminl fluid 3 Ure N (mg/100 ml) were 82.5, 77.1 nd 82.1 mm/ l for control cows nd Totl VFAs (mm) cows fed diets 2 nd 3, respectively (P, 0.65; Tle Individul VFAs (%): 5). No significnt difference ws detected mong Acette (A) Propionte (P) diets for the individul VFA concentrtions (per- Butyrte centge of totl) during the time efore the morning A:P mel ws offered nd 8 h lter (Tle 5). 1 See footnote d in Tle 1. No difference in men plsm glucose concen,: Mens within row without common superscript differ trtions could e detected mong diets (Tle 6). ccording to P vlue given. The stndrd devition nd coefficient of vrition of Tle 6 Effect of diet on plsm glucose nd insulin concentrtions 3 Diet P. F Contrst vs X SD X SD X SD 1 Glucose (mg/ 100 ml) CV (%) Insulin (mu/ l): Week Week ,: Mens within row without common superscript differ ccording to P vlue given. 1 Men of 30 smples tken from ech of seven cows per tretment during experimentl period. 2 Men of five smples tken from ech of 14 cows per tretment during weeks one nd seven postprtum. 3 See footnote d in Tle 1.

7 I. Bruckentl et l. / Livestock Production Science 63 (2000) Tle 7 Effect of diet on reproductive performnce Diet S.E.M. P. F No. of cows Retined plcent Metritis Dys to first ovultion Dys to first AI Dys open AI per conception Conception rte (%): First AI 28.6 (14) 21.4 (14) 28.6 (14) Second nd third AI 30.8 (13) 25.0 (16) 33.3 (12) See footnote d in Tle 1. In prentheses, totl numer of AI. plsm glucose concentrtion for control cows were were fed nerly in similr mounts in ll diets. smller (P, nd P, 0.062, respectively), Soyen mel nd rpeseed mel were supplemented thn those for cows fed diets 2 nd 3. Plsm insulin to ll diets t similr concentrtions (Tle 1) nd concentrtions incresed from the first to the seventh chnges in dietry UDCP were chieved y the week postprtum (P, 0.001; Tle 6), ut there ws ddition of 25 g/kg of CGM. Dietry UDCP in oth no significnt difference mong diets. diets ws incresed y 1.1%, which in diet 2 ws on The reproductive performnce of the experimentl the ccount of the dietry RDCP, ut not in diet 3. cows is presented in Tle 7. One cow of ech diet Dietry RDCP in diet 3 ws the sme s tht in the ws removed efore eing dignosed s pregnnt. control diet, ut dietry CP concentrtion ws in- On ech diet, 10 of the cows ecme pregnnt. No cresed y 1.3%. Accordingly, shortge of RDCP significnt differences mong diets could e detected tht ws required for optiml fermenttion y rumifor ny of the reproduction prmeters except for nl microes could not explin the reduced DMI of metritis, which ws detected in one control cow ut cows fed diets 2 nd 3. More likely, fctors relted to in seven cows fed diet 2 nd in six cows fed diet 3. CGM in these diets were responsile for the negtive effect on DMI. Most feedstuffs tht re high in UDCP re of niml source. Reduced intke of diets 4. Discussion supplemented with fish mel (Bruckentl et l., 1989; Wholt et l., 1991; Atwll nd Erfle, 1992), 4.1. Dry mtter intke met nd one mel (Mjeesh et l., 1996), nd lood mel nd fether mel (Wltz et l., 1989) Men DMI of cows fed diets 2 nd 3 ws lower y were ttriuted to pltility or high ft contents. 2.4 nd 3.4 kg/ d, respectively, thn tht of the Reduced DMI s result of feeding CGM ws control cows (Tle 3). Differences in DMI mong reported for cows (Fleck et l., 1988; Bluwiekel et tretments could not e nlyzed sttisticlly ecuse l., 1990; Wholt et l., 1991; Wheeler et l., 1995) the cows were fed s group. However, since CGM nd lms (Stples et l., 1990). However, others is used in lrge quntities in diry cow rtions, nd (Holter et l., 1992; Cozzi nd Poln, 1994) reported other performnce prmeters like s BW nd BCS, no effect of CGM on DMI. Reviewing the 12-yer were significntly ffected y CGM supple- literture of RUDCP in diry cows diets, Sntos et menttion, it ws ssumed tht this issue should e l., (1998) concluded tht supplementtion of CGM ddressed. resulted in mostly negtive results. However, no The reduced DMI might e ttriuted to the CGM consistent effect nd no definite explntion on component of diets 2 nd 3 ecuse other ingredients dietry composition sis could e shown.

8 138 I. Bruckentl et l. / Livestock Production Science 63 (2000) The similrity in the response of cows on diets 2 plemented cows lost 58 kg BW during 14 to 16 nd 3 to supplementl CGM in DMI, BW loss nd weeks of lcttion. Cows fed fish mel lost 30 kg BCS chnge proves the sensitivity of high-yielding during four weeks nd cows fed SBM lost 37 kg cows short time fter clving to dietry CGM. during 10 weeks (Wholt et l., 1991). Differences in According to Wheeler et l. (1995), dietry RUDCP men DMI etween cows fed the control diet nd level is responsile for incresing insulin concen- cows fed diets 2 nd 3 during 45 d of BW loss were trtions of cows in erly lcttion. This period is 2.4 nd 3.4 kg/ d, respectively, which re equivlent chrcterized y low DMI nd high milk production, to 186 nd 263 Mcl NEl per 45 d, respectively. which is mintined y extensive lipolysis of ftty These results correlte well with the energy equivtissues nd gluconeogenesis. Blood insulin concen- lent of 270 Mcl for 55 kg BW loss (NRC, 1989) of trtion is very low immeditely fter clving (Kop- the CGM fed cows. However, the grdul increse in rowski nd Tucker, 1973; Hrt et l., 1978; postclving DMI msks the ctul BW loss, which Bluwiekel et l., 1990), which enles grdul might e even greter. Dys to miniml ody increse in DMI. The CPS tretment (comintion condition (BC) my etter represent the period of protein supplement) in Wheeler et l. (1995) experi- negtive energy lnce. Dys to miniml BC score ment, included CGM without soyen mel (SBM), (BCS) were greter thn dys to miniml BW y 25, nd ws most effective in incresing lood insulin 21 nd 22 d for control cows nd cows fed diets 2 level. Similr results were reported y Lndu et l. nd 3, respectively (Tle 4). Likewise, the rtes of (1996), s insulin level ws incresed in the lood of increse in BCS fter miniml vlue ws reched up CGM-fed ewes ut not in SBM-fed ewes. In the to the end of the experiment, were , present tril, plsm insulin concentrtions incresed nd BCS units per dy for the control cows during seven weeks postprtum (P, 0.001; Tle 6). nd cows on diets 2 nd 3, respectively. This However, no significnt difference etween control emphsizes the metolic difficulty of the CGM-fed cows nd cows fed diets 2 nd 3 could e found, cow to recover nd shift to positive energy lnce except tht the increse in insulin tended to e fster lter in lcttion. for diets 2 nd 3 (n increse of 3.16, 5.01 nd 4.41 These results re not comptile with our expectmu/l per seven weeks, on diets 1, 2 nd 3, respec- tions for etter energy lnce y cows fed the tively). The decrese in feed intke y cows fed diets diets supplemented with UDCP (Grnsworthy nd 2 nd 3 nd the prole leveling down CGM intke, Cole, 1990; Dhimn nd Stter, 1993; Bruckentl et pprently voided the extr excretion of insulin. l., 1996). It seems tht the effect on DMI, BW loss Greter fluctutions in the plsm glucose concen- nd BCS of cows on diets 2 nd 3, during the first trtion of cows fed diets 2 nd 3, s compred with period postprtum, cnnot e ttriuted to the higher those of control cows (Tle 6), my lso point to undegrdility of dietry CP ut to more specific non-stle glucose metolism. Lter in lcttion, effect of CGM. when pek feed intke is reched, lood insulin concentrtions re much higher, nd dietry CGM 4.3. Reproductive performnce might not hve the sme impct on metolism. This my explin contrdictory reports on the effect of Diry cows cnnot mintin positive dietry dietry CGM on DMI y milking cows. energy lnce erly in lcttion. A correltion ws shown etween energy lnce t the eginning of 4.2. Body weight nd milk yield lcttion nd fertility (Andersson et l., 1991). According to Butler nd Smith (1989), negtive Postprtum loss of BW ws significntly greter energy lnce proly cts similrly to undernutrifor cows fed diets 2 nd 3 thn for control cows tion nd my e mnifested in delyed ovrin (Tle 4 nd Fig. 1). However, no differences were ctivity nd reduced fertility. In the present study, found in milk yield (Tle 3 nd Fig. 1) or milk the protocol for reproductive mngement included composition mong diets. Similr results were re- n extensive follow-up of cows from clving ported y Wholt et l. (1991), s CGM-sup- throughout the experiment. Although significnt

9 I. Bruckentl et l. / Livestock Production Science 63 (2000) differences mong diets were demonstrted for men Acknowledgements BW loss nd for BCS, experimentl effects on reproduction were not detected (Tle 7). Similr The uthors thnk Chnn Lehrer nd Moshe results were reported y Br-Peled et l. (1995), Nikcht for technicl ssistnce. when BW loss nd reduced BCS were much greter for suckled cows thn for the control nd for cows milked six times dily. However, fertility of the References suckled cows ws similr to the cows on the two other tretments (personl communiction). Fertility Arieli, A., Bruckentl, I., Smoler, E., Prediction of duodenl of ewes fed with CGM for four dys efore nd four nitrogen supply from degrdtion of orgnic nd nitrogenous mtter in-situ. J. Diry Sci. 72, dys fter tretment with prostglndin F 2, ws Andersson, L., Gustfsson, A.H., Emnuelson, U., Effect of etter thn tht of ewes fed SBM or isoenergetic hyperketonemi nd feeding on fertility in diry cows. supplement (Lndu et l., 1996). They concluded Theriogenology 36, 521. tht insulin nd glucose metolism my e involved Atwll, A.S., Erfle, J.D., Effects of feeding fishmel to cows in the effect of supplementl protein. Likewise, on digestiility, milk production nd milk composition. J. Diry Sci. 75, etter fertility hs een reported for cows fed low s Br-Peled, U., Mltz, E., Bruckentl, I., Folmn, Y., Kli, Y., compred with high CP degrdle diets (Ferguson Gcitu, H., Lehrer, R., Knight, C.H., Roinzon, B., Voet, H., et l., 1988; Bruckentl et l., 1989; Cnfield et l., Tgri, H., Reltionship etween frequent milking or 1990; Ferguson et l., 1993). The incidence of suckling in erly lcttion nd milk production of high retined plcent is ffected minly y the condition producing diry cows. J. Diry Sci. 78, Brton, B.A., Rosrio, H.A., Anderson, G.W., Grindle, B.P., of the cow efore nd during clving, nd no Crroll, D.J., Effects of dietry crude protein, reed, tretment effect ws expected. Appernce of met- prity nd helth sttus on the fertility of diry cows. J. Diry ritis is induced y the postprtum physiologicl Sci. 79, condition of the cow. The higher incidence of Bluwiekel, R., Hoover, W.H., Slider, S.D., Miller, T.K., metritis in cows fed diets 2 nd 3 compred with Effects of fish mel protein supplementtion on milk yield nd composition nd lood constituents of diry cows. J. Diry Sci. control cows (Tle 7) could hve een result of 73, greter negtive lnce of energy nd of other Bruckentl, I., Drori, D., Kim, M., Lehrer, H., Folmn, Y., nutrients, which could increse the sensitivity of Effect of source nd level of protein on milk yield nd genitl orgns to pthogens. However, ecuse of reproductive performnce of high-producing primiprous nd good mngement, including erly detection of dis- multiprous diry cows. Anim. Prod. 48, Bruckentl, I., Tgri, H., Arieli, A., Zmwell, S., Ahroni, Y., orders, timely tretment nd susequent monitoring Genizi, A., The effect of undegrdle crude protein for the efficcy of tretment, no effect on dys to supplementtion on milk production nd composition nd first ovultion or dys to first AI could e detected reproduction of erly lctting cows. J. Anim. feed Sci. 5, (Tle 7). Howrd et l. (1987) nd Brton et l (1996) climed tht mny declines in reproduction Butler, W.R., Smith, R.D., Interreltionships etween energy lnce nd postprtum reproductive function in diry cttle. J. ttriuted to nutritionl fctors could e controlled Diry Sci. 72, y proper veterinry mngement. Cnfield, R.W., Sniffen, C.J., Butler, W.R., Effect of excess degrdle protein on postprtum reproduction nd energy lnce in diry cttle. J. Diry Sci. 73, Conclusions Crroll, D.J., Jerred, M.J., Grummer, M.J., Coms, D.K., Pierson, R.A., Huser, E.R., Effect of ft supplementtion nd immture lflf to concentrte rtio on plsm progesterone, DMI of diry cows during the first period fter energy lnce nd reproductive trits of diry cttle. J. Diry clving is low nd cnnot fulfill energy requirements Sci. 73, for production. Feeding the cows diets contining Cozzi, G., Poln, C.E., Corn gluten mel or dried rewers pproximtely 40 g/kg CGM might reduce DMI nd grin s prtil replcement for soyen mel in the diet of Holstein cows. J. Diry Sci. 77, increse their negtive energy lnce. Reduced Dhimn, T.R., Stter, L.D., Protein s the first limiting DMI my e result of the effect of dietry CGM on nutrient for lctting diry cows fed high proportions of good lood insulin level during erly lcttion. qulity lflf silge. J. Diry Sci. 76,

10 140 I. Bruckentl et l. / Livestock Production Science 63 (2000) Ferguson, J.D., Blnchrd, T., Gllign, D.T., Hoshll, D.C., Ørskov, E.R., McDonld, I., The estimtion of protein Chlup, W., Infertility in diry cttle fed high degrdility in the rumen from incution mesurements percentge of protein degrdle in the rumen. J. Am. Vet. weighted ccording to the rte of pssge. J. Agric. Sci. Med. Assoc. 192, (Cm.) 92, Ferguson, J.D., Cllgn, D.T., Blnchrd, T., Reeves, M., Ostergrd, V., Korver, S., Solu, H., Anderson, B.B., Oldhm, J., Serum ure nitrogen nd conception rte: the usefulness of test Wiktorsson, H., Min report E.A.A.P working group informtion. J. Diry Sci. 76, on: efficiency in the diry cow. Livest. Prod. Sci. 24, Fleck, A.T., Lusy, K.S., Owens, F.N., McCollum, F.T., Ron, M., Br-Ann, R., Wiggns, G.R., Fctors ffecting Effects of corn gluten feed on forge intke, digestiility nd conception rte of Isreli Holstein cttle. J. Diry Sci. 67, ruminl prmeters of cttle fed ntive grss hy. J. Anim. Sci , Sntos, F.A.P., Sntos, J.E.P., Theurer, C.B., Huer, T., Grnsworthy, P.C., Cole, D.J.A., The importnce of intke Effects of rumen-undegrdle protein on diry cow performin feed evlution. In: Wiesmn, J., Cole, D.J.A. (Eds.), nce: 12-yer literture review. J. Diry Sci. 81, Feedstuff Evlution, Butterworths, London, p SAS, SAS User s Guide: Sttistics, Version 5 ed., SAS Hrt, I.C., Bines, J.A., Mornt, S.V., Ridley, J.L., Endocrine Institute, Cry, NC. control of energy metolism in the cow: comprison of the Skln, D., Molem, U., Folmn, Y., Effect of feeding levels of hormones (prolctin, growth hormone, insulin nd clcium sops of ftty cids on production nd reproduction thyroxine) nd metolites in the plsm of high- nd low- responses in high producing lctting cows. J. Diry Sci. 74, yielding cttle t vrious stges of lcttion. J. Endocrinol. 77, Spicer, L.J., Vernon, R.K., Tucker, W.B., Wttermnn, R.P., Hogue, Holter, J.B., Hyes, H.H., Urn, Jr. W.E., Rmsey, S., Ridequt, J.F., Adms, G.D., Effect of inert ft on energy lnce, H., Response of Holstein cows to corn gluten mel used plsm concentrtions of hormones, nd reproduction in diry to increse undegrdle protein in erly or lter lcttion. J. cttle. J. Diry Sci. 76, Diry Sci. 75, Stples, C.R., Thtcher, W.W., Clrk, J.H., Reltionship Howrd, H.J., Alseth, E.P., Adms, G.D., Bish, L.J., McNew, etween ovrin ctivity nd energy sttus during the erly R.W., Dwson, L.J., Influence of dietry protein on postprtum period of high producing diry cows. J. Diry Sci. reproductive performnce of diry cows. J. Diry Sci. 70, 73, Tgri, H., Comprison of the efficiency of protein con- Koprowski, J.A., Tucker, H.A., Bovine serum growth tined in lucerne hy nd soy-en mel for sheep. Br. J. Nutr. hormone, corticoids nd insulin during lcttion. Endocrinolo- 23, gy 93, Tyrrel, H.F., Reid, J.T., Prediction of the energy vlue of Lmming, G.E., Alterntives to invsive genetic engineer- cow s milk. J. Diry Sci. 48, ing in niml production. In: Grnsworthy, P.C., Wisemn, J. Vn Soest, P.J., Roertson, J.B., Lewis, B.A., Methods for (Eds.), Recent Advnces in Animl Nutrition, University Press, dietry fier, neutrl detergent fier, nd nonstrch polysc- Nottinghm, pp chrides in reltion to niml nutrition. J. Diry Sci. 74, Lndu, S., Houghton, J.A.S., Mwhinney, J.R., Inskeep, E.K., Protein sources ffect folliculr dynmics in ewes ner Wltz, D.M., Stern, M.D., Illg, D.J., Effect of ruminl the onset of the reeding seson. Reprod. Fertil. Dev. 8, protein degrdtion of lood mel nd fether mel on the intestinl mino cid supply to lctting cows. J. Diry Sci. 72, Mjeesh, S.J., Arieli, A., Bruckentl, I., Zmwell, S., Tgri, H., Effect of type of protein supplementtion on duodenl Wheeler, J.G., Amos, H.E., Froetschel, M.A., Coomer, J.C., mino cid flow nd sorption in lctting diry cows. J. Mddox, T., Responses of erly lcttion cows fed Diry Sci. 79, winter nd summer nnul forges nd undegrdle intke Neel, R.L., McGillrd, M.L., Interctions of high milk nd protein. J. Diry Sci. 78, reproductive performnce in diry cows. J. Diry Sci. 76, Wholt, J.E., Chmiel, S.L., Zjc, P.K., Bcker, L., Blethen, D.B., Evns, J.L., Dry mtter intke, milk yield nd com- NRC, Nutrient Requirements of Diry Cttle, Ntionl position nd nitrogen use in Holstein cows fed soyens, fish Reserch Council, Ntionl Acdemy Press, Wshington, DC. or corn gluten mels. J. Diry Sci. 74,