Metabolizable Energy Requirements for Broiler Breeder in Different Environmental Temperatures

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1 Interntionl Journl of Poultry Science 11 (7): , 2012 ISSN Asin Network for Scientific Informtion, 2012 Metolizle Energy Requirements for Broiler Breeder in Different Environmentl Tempertures M.E. Reyes, C. Sls nd C.N. Coon 1 Universidd Ncionl de Loj, Loj, Ecudor Ciudd Universitri Guillermo Flconí Espinos "L Argeli" - PBX: Csill Letr"S" 2 Escuel de Zootecni, Universidd de Cost Ric 3 Center of Excellence for Poultry Science, University of Arknss, Fyetteville, AR 72701, USA Astrct: A 10 wk feeding experiment ws conducted to develop model for predicting the ME requirement for roiler reeder hens housed in different environmentl tempertures. Three groups of 50 Co 500 roiler reeder hens were individully housed in reeder cges locted in environmentlly controlled rooms set t 15.5, 23 nd 30 C. Ech reeder ws given n intrmusculr injection of Tmoxifen (TAM) (5 mg/kg BW) in corn oil t dys 1 nd 4 to stop egg production. Ten reeders from ech environmentl temperture were scrificed for crcss composition nlysis t the eginning of the study. Breeders, during the nonlying period, housed t 15.5 C were fed 100 g providing 285 kcl MEn//d (2851 kcl/kg; 16%CP) nd reeders housed t 23 C nd 30 C were fed 93 g providing 265 kcl MEn//d of sme diet. Five reeders were scrificed from ech environmentl room fter the reeders resumed egg production. The ME requirement for mintennce (MEm) determined during the non-lying period ws 104.3, 98.1 nd 99.4 kcl/kg for irds housed in 15.5, 23 nd 30 C, respectively. At first egg, 136, 130 nd 128 g/ird/d of sme diet previously fed during the non-lying period provided 388, 371 nd 365 kcl MEn//d to roiler reeder hens housed t 15.5, 23 nd 30 C, respectively. The egg numer, egg weight nd BW chnge for ech reeder during egg production ws evluted through the reminder of the 10 wk period. At the end of the tril, ll irds were scrificed nd frozen t -4 C for crcss composition nlysis. Body weight dt collected during the non-lying period ws used to construct single eqution y plotting Metolizle Energy (ME) ginst ody weight chnge (BW)) for ech individul hen to clculte the MEm. Egg production nd egg weights were recorded dily fter egg production resumed. The MEg nd MEe requirement for BW gin nd egg production were determined for reeders in ech of the environmentl tempertures sed on the energy content of crcss nd egg mss nd the respective efficiency of energy utiliztion. The verge MEg nd MEe for the three environmentl tempertures ws 5.8 kcl/g nd 2.3 kcl/g, respectively. Three equtions were developed from the feeding experiment to predict ME needs for reeders: Eq. 1: (ME = BW 2 [ T] + 5.8G + 2.3EM); Eq. 2: (ME = BW [ T (T ) ] + 5.8G + 2.3EM); 2 Eq. 3: (ME = BW [ T (T ) ] + BW) (1/0.77 x ERf + 1/0.37 x ERp) + ECE/0.73 x EM), where ME = Metolizle Energy (kcl), BW = Body Weight (kg ), T = Temperture ( C), BW) = Body Weight chnge (g/d), ERf = Energy Retined s ft (kcl), ERp = Energy Retined s protein (kcl); ECE = Energy Content of Eggs (kcl/g) nd EM = Egg Mss (g). Key words: Metolizle energy, prediction models, environmentl temperture, roiler reeders INTRODUCTION Although energy is not nutrient per se, from the iologicl nd economic stnd point, energy plys fundmentl role in formulting diets for roiler reeder hens. Feed intke of roiler reeders is regulrly restricted during rering to prevent reproduction nd helth prolems t lter ge nd to ssure optiml performnce. Metolizle Energy (ME) requirements for roiler reeder hens re known to e higher thn for commercil lyers; nevertheless, the requirements for roiler reeders is often extrpolted from studies conducted minly with Leghorn type hens (Leeson, 2003). The fctoril pproch is one of the most common wys of prtitioning the ME requirements into mintennce, gin nd egg production (Zhng nd Coon, 1994). Environmentl temperture plys n importnt role in regulting energy requirements for poultry. Skomur et l. (2011) suggests tht dditionl environmentl-nutrition reserch is needed to help stndrdize the nutritionl chnges tht occur. The ojective of the present study ws to determine the energy requirement for mintennce, ody weight gin nd egg mss output for roiler reeder hens housed t different environmentl tempertures. Corresponding Author: C.N. Coon, Center of Excellence for Poultry Science, University of Arknss, Fyetteville, AR 72701, USA 453

2 Tle 1: Composition nd nlysis of diet fed to roiler reeder hens housed t 3 different environmentl tempertures Ingredients Composition (%) Corn Soyen mel solvent ext. 47.5% protein Choline Chloride 60% 0.07 Lysine 0.43 Diclcium PO Ethoxyquin 66% 0.02 Poultry ft 2.45 reeders t the end of lying period. Clcium cronte 6.43 Kemin Mold Cur 50% Propionic Acid 0.05 Slt 0.39 A Trce minerl CVI Breeders 0.06 B CVI Breeder premix Crude protein PCT Clculted metolizle energy (kcl/kg) Anlyzed AMEN (kcl/kg) C Clculted crude protein Anlyzed crude protein A Provides per kg of diet: Mn 120 mg; Zn 120 mg; Fe 60; Cu 12 mg; I 1.2 mg; Mg 31.8 mg nd C 855. B Provides per kg of diet: vitmin D kiu; vitmin A 14.7 KIU; vitmin E 80.7 IU; nicin 94.7 mg; D-Pntothenic cid 39.2 mg; rioflvin 21.1 mg; pyridoxine 12.4 mg; thimine 6.3 mg; folic cid 3.9 mg; iotin 0.44 mg; 29.7 MCG. C Crude protein = % MATERIALS AND METHODS Birds nd mngement: Three groups of 50 Co 500 roiler reeder hens, 32 weeks of ge, were plced in individul femle roiler reeder cges in three different environmentlly controlled rooms (Co-Vntress, 2008). Cges (47 cm high, 30.5 cm wide, 47 cm deep) were ech equipped with n individul feeder nd nipple drinker. Birds were fed individully nd provided with free ccess to wter t ll times. During 2-week dpttion period, temperture ws grdully djusted to 15.5, 23 nd 30 C efore the initition of the experiment. The lighting regimen ws 16 hr light nd 8 h drkness per dy. Temperture of ech room ws recorded ech dy t 08:30 in the morning throughout the experimentl period. During the non-lying period, 93 g/ird/d of reeder diet (2851 kcl AMEn/kg; 16% CP) (Tle 1) provided 265 kcl MEn//d for reeders housed t 23 nd 30 C nd 100 g/ird/d provided 285 kcl MEn//d for reeders housed t 15.5 C. During the lying period, 136, 130 nd 128 g/ird/d of sme diet (2851 kcl AMEn/kg; 16% CP) (Tle 1) provided 388, 371 nd 365 kcl MEn//d to roiler reeder hens housed t 15.5, 23 nd 30 C, respectively. Generl procedures for flock mngement nd collection of egg nd crcss smples were similr to the experimentl design descried y Reyes et l. (2011). Egg production ws stopped utilizing 2 injections (5 mg/kg BW) of Tmoxifen (TAM) (estrogen ntgonist) in corn oil on dys 1 nd 4 t the eginning of the study. Ten reeders from ech environmentl room were scrificed y CO2 inhltion nd frozen t -4 C for crcss composition nlysis. Five dditionl reeders from ech environmentl room were scrificed for crcss composition nlysis when the reeders resumed egg production. The remining reeders from ech environmentl temperture were scrificed for crcss composition nlysis t the termintion of the 10 wk period to represent the ody composition of Breeder performnce dt, egg nd ody tissue smples otined from the three environmentl tempertures, egg energy content, crcss energy content, energy retined in the ody, energy for egg production, energy coefficients nd mintennce energy requirement were determined using the sme procedures nd clcultions descried y Reyes et l. (2011). Three ME requirement models for roiler reeders were developed for different environmentl tempertures. The ME requirement for mintennce (MEm) ws clculted using the individul dt collected during the non-lying period in order to reduce interdependence mong fctors involved in egg production. Sttisticl nlysis: Stndrd sttisticl procedures were used to otin liner regression equtions for predicting MEm (Mendenhll nd Sincich, 2003). Regression nlyses nd polynomil equtions were fitted using the lest squres procedure of JMP IN Softwre (SAS Institute) ( ). Dt were sujected to one-wy ANOVA using the Generl Liner Models procedure of SAS ( ). When significnt F sttistic ws detected, mens were seprted using Tukey s test t 5% of proility (Freund nd Wilson, 1997). RESULTS AND DISCUSSION Although the tempertures were mechniclly kept constnt for ech environmentl room, slight fluctutions occurred throughout the tril. The overll registered men tempertures nd stndrd devitions of environmentlly controlled rooms were 15.5 (±0.49), 23 (±0.29) nd 30 (±0.46) C. Egg production dropped to zero 7 dys fter the first TAM injection. Broiler reeder hens housed in rooms mintined t 15.5, 23 nd 30 C environmentl temperture reched pek egg production in 25, 20 nd 22 dys fter lst TAM injection, respectively. Hens tht lid few or no eggs during the experiment were not used for clculting MEe. Metolizle energy for mintennce: Dt collected only during the non-lying period were used to clculte MEm. The MEm requirements otined were 104.3, 98.1 nd 99.4 kcl/kg for irds housed in 15.5, 23 nd 30 C, respectively (Fig. 1). 454

3 Fig. 1: Actul nd predicted ME for mintennce for reeder hens housed t 15.5, 23 nd 30 C Prmeter estimtes Term Estimte Std Error t Rtio Pro> t Intercept (23 C) < BW chnge g/d < C C < Fig. 2: ME for mintennce (MEm) s function of environmentl temperture Liner Fit: 2 MEm (kcl/kg ) = T ( C); R = 0.50 Polynomil Fit Degree = 2: MEm (Kcl/kg ) = T ( C) (T ( C) )2 T ( C); R = 0.61 Temperture effects on MEm indicted non-liner reltionship etween ME intke s function of environmentl temperture (Fig. 2). The dt collected were utilized to estimte temperture effects on MEm. The three equtions used for MEm were: 1.) Mem = BW 2 [ T](R = 0.50), 2.) MEm = BW [ T (T ) ] (R = 0.61) nd 3.) MEm = BW 2 2 [ T (T ) ] (R = 0.54). MEm is the requirement of ME for mintennce nd T is temperture in degree Celsius. MEm for roiler reeder hens kept t 30 nd t 15.5 C environmentl temperture ws slightly higher (99.4 kcl/kg nd kcl/kg, respectively) thn tht of reeder hens kept t 23 C (98.1 kcl/ kg ). Skomur (2001) developed prediction equtions for clculting ME requirements for roiler reeder hens t different tempertures using the fctoril pproch. MEm requirements were otined y comprtive slughter. MEm for roiler reeders housed t 15.5 C otined in the present study ( kcl/kg ) re in close greement with those otined y using the prediction eqution elorted y Skomur (2001) (i.e. 103 kcl/kg ). However, MEm for irds kept t 23 nd 30 C environmentl tempertures clculted in the present study (98.1 kcl/kg nd 99.4 kcl/kg, respectively) were 9% higher thn tht clculted y Skomur s eqution (89 kcl/kg nd 90 kcl/kg, respectively). Rello et l. (2004) lso evluted the effect of environmentl temperture on the metolizle energy requirements of roiler reeder hens nd reported 111.2, 91.5 nd 88.5 kcl/kg /dy for irds kept in cges t 13, 21 nd 30 C. Rello et l. (2004) reported vlues tht were 10.9% higher for irds kept t 13 C nd 6.5% lower for irds kept t 30 C. The lower MEm requirement for the reeders kept t 15.5 C in present experiment cn e ttriuted to the 2.5 C higher temperture compred to Rello et l. (2004). An inverse liner reltionship etween environmentl temperture nd MEm hs een reported in the literture. As temperture increses, energy requirements for mintennce decrese, within rod rnge of tempertures (Hurwitz et l., 1980; NRC, 1981). Skomur et l. (2003) lso oserved depression in ME requirements for mintennce t incresing tempertures in roiler reeder pullets. Skomur (2004) indictes tht liner reltionship should e considered for predicting the MEm when environmentl tempertures re similr to the thermo-neutrl temperture for poultry. The present study using TAM treted hens supports non-liner reltionship etween temperture nd MEm. Broiler reeder hens housed t 30 C hd higher MEm thn roiler reeders housed t thermo-neutrl temperture (21-23 C). The ility to detect slight increse in MEm for reeders housed t 30 C compred to 23 C my hve een possile ecuse the dt ws collected from individul roiler reeder hens nd the environmentl temperture ws kept constnt throughout the experiment. Broiler reeders housed in constnt 30 C temperture in present study would proly e more het stressed thn reeders housed in cyclic tempertures with sme 30 C 24h men wrm temperture. Previous reserch with commercil lyers 455

4 housed in constnt tempertures ove 30 C show rpid decrese in feed intke nd performnce compred to lyers housed in similr 24 h men temperture from cyclic tempertures rnging from C (Zollitsch et l., 1996). Broiler reeders would require dditionl energy to dissipte het loss compred to commercil lyer ecuse of the 3 dditionl odyweight/surfce re (kg/cm ). The reeders in the constnt 30 C wrm temperture my need more MEm to provide energy for thermoregultory mechnisms such s pnting cused y the hot environmentl tempertures (Wiel nd McLeod, 1995). A qudrtic effect of temperture ove 27 C on requirements of MEm hs lso een suggested in the literture for roiler reeder hens (Skomur, 2004; 2001; Leeson nd Summers, 1997; Rello et l., 2006) nd for roilers (Longo et l., 2006). Metolizle energy for ody weight gin: There ws significnt difference (p<0.05) in weight gin mong hens mintined t different environmentl tempertures (Tle 2). Broiler reeder hens housed t 15.5, 23 nd 30 C gined n verge of 41.4, 12.0 nd 23.1 g during the non-lying period, respectively. It is importnt to recll tht, during the non-lying period, reeder hens housed t 15.5 C received n dditionl 7 g/ird/d (~20 kcl ME) more thn hens housed t 23 nd 30 C. The verge MEg ws 5.8 kcl/g (Tle 3) in the present study nd the men efficiency for MEg ws 57%. The verge ERp nd ERf were 40 nd 60.3%, respectively. Men prtil efficiencies for ft (kf) nd protein (kp) for reeders were 0.77 nd 0.38, respectively. These vlues were used to construct the prediction eqution for clculting ME for roiler reeder hens. The 5.8 kcl/g estimte of ME needed for ody weight gin is similr to the vlue estimted y NRC (1994) (5.5 kcl/g) nd y Emmns (1974) (5 kcl/g) for lying hens. Differences in ME requirements for gin could e due to differences in ody composition nd efficiency of energy utiliztion (Romero et l., 2009). Romero nd group indicte tht liner models ssume constnt slopes tht imply tht the clcultions re only pplicle to irds with equl chrcteristics of BW gin. The Cndin reserchers suggest non-liner model insted. Body weight chnges (BW)) of reeders used in the present study were different mong groups. The reltively low weight gin of reeders housed t 23 nd 30 C ( nd 1.34 g/d, respectively) indictes tht ME intke ws only slightly ove the mintennce requirement nd the dditionl dietry energy ws lmost eqully prtitioned into ody ft nd protein (Tle 3). The BW) of reeder hens housed t 15.5 C ws lrger since they were fed pproximtely 20 kcl dditionl ME. The ody composition of the BW) ws lso different for reeders housed t 15.5 C ecuse the reeders gined higher percentge of ft. The results of this experiment would indicte tht if reeders housed t 23 nd 30 C hd received lrger ME ove mintennce, the rtio of protein: ft retined my hve een different. Breeders seemingly ecome very efficient when fed lower levels of energy intke since little energy ws left for ody weight chnge. Overll, greter percentge of energy utilized for BW) ws deposited s ft during the feeding study. The incresed ft retention for reeders housed t 15.5 C ws in greement with the findings of Person nd Herron (1981); Sprtt nd Leeson (1987); Sprtt et l. (1990). Experiments conducted during the complete lying period with Co 500 roiler reeder hens housed in individul cges (Sun nd Coon, 2005; Sun et l., 2006) showed the composition of gin for BW) for reeder hens ws 75% ft nd 25% protein. Broiler reeders tht were 10-20% ove Co stndrd t the eginning of production retined more energy s ft thn s protein, wheres reeders tht were 10-20% elow the Co stndrd retined more protein during the productive cycle (20-65 weeks). Tle 2: Body weight chnge nd dily ody weight chnge of roiler reeder hens during the non-lying period Tempertures ( C) Chrcteristics Averge Initil ody weight, kg 3.73± ± ± Finl ody weight, kg 3.77± ± ± Body weight gin, g 41.39± ± ± Body weight gin, g/d 2.59± ± ± Tle 3: Prtil efficiencies for ody weight gin, ft nd protein retention nd ME for ody weight gin during the non-lying period Tempertures ( C) Chrcteristics Averge kg, % ER s DM, kcl/d 16.73± ± ± ERp, % ERf, % Kf kp Meg

5 Boekholt et l. (1994) concluded tht dily retention of reeder hens. The verge vlue of kg of 0.57 (Tle 3) protein nd ft ws linerly relted to energy retention. my e etter estimte for predicting the energy The uthors found tht more ft thn protein ws requirements of ME for roiler reeder hens under retined when growing roilers were fed t incresing prcticl conditions. energy intkes, ut when energy intkes were lower, Birds housed t 15.5 C hd higher efficiencies (0.96 constnt dily protein retention nd vrile ft nd 0.47) for ft nd for protein synthesis thn irds retention occurred. The findings of Boekholt et l. (1994) housed t wrmer tempertures. Birds housed t support the incresed ft gin, kf nd the oserved 15.5 C gined pproximtely 2.6 g per dy, 69% of rtio (ft: protein) of retined energy during the non- which ws ft gin (Tle 3). These results cn e lying period especilly for the reeders fed dditionl compred with those reported y Sprtt et l. (1990) who energy nd housed t 15.5 C (Tle 3, 6). found 0.96 nd 0.51 efficiency for ft nd protein, Broiler reeders housed t 15.5 C, which received n respectively. Body weight gin (2.6 g/d) oserved in extr lloction of energy (~20 kcl/d) gined more reeders housed t 15.5 C ws lso similr to the 2-3 weight nd hd higher kg thn the other reeders g/d gin reported y Sprtt et l. (1990). Breeders housed t higher tempertures (Tle 3). One of two housed t 30 C hd higher kf (0.73) thn reeders possile scenrios my hve produced this result. The housed t 23 C (0.61). The reeders housed t 30 C MEm for roiler reeders housed t the cold temperture retined higher percentge of gin s ft compred to my hve een overestimted since there ws higher reeders housed t 23 C possily ecuse of lower percentge of the reeder popultion housed t 15.5 C energy requirements for ft synthesis compred to tht gined weight compred to reeder hens housed t protein retention (Boekholt et l., 1994). Breeders 23 C nd 30 C. A more likely explntion is the het housed t 23 C hd reltively low kf, ody weight gin increment from extr feed provided the reeders during nd ERf compred to reeders housed t 30 C, which production spred the energy needed for MEm so tht were fed the sme mount of ME. This my suggest tht more energy ws ville to e converted into ody either there ws preference for mintining protein tissue. Zhng nd Coon (1997) nd McLeod (2002) retention t the expense of ft (Boekholt et l., 1994) or hypothesized tht higher prtil efficiencies of energy more energy ws needed t 23 C to keep the irds retention t cool tempertures re the result of the het wrm (El Husseiny nd Creger, 1980), leving less increment of feeding tht replces thermoregultory het energy ville for storge s ft. The men kp (0.37) production nd therefore, the requirements for nd kf (0.77) (Tle 3) were used to construct the mintennce. fctoril model in the present study. The estimted kg for roiler reeders housed t 23 C ws 0.51 nd slightly higher thn kg of 0.49 for roiler Metolizle energy for egg production: Temperture reeders housed t 30 C lthough oth groups received significntly (p<0.05) ffected egg production, egg mss, the sme feed llownce. Additionl energy would e egg weight nd some egg composition mesurements needed to meet the demnd for dissipting het for (Tle 4 nd 5). reeders housed t 30 C resulting in higher MEm nd Egg Production (EP) nd Egg Mss (EM) of hens housed lower kg. An dditionl input of energy hs een shown to e necessry to dissipte metolic het in chickens nd turkeys housed t tempertures ove 30 C (Hurwitz et l., 1980). The higher retined energy s ft in reeders housed t t 15.5 nd 30 C ws lower thn EP nd EM of hens mintined t 23 C. Egg Weight (EW) ws significntly lower for reeders housed in 30 C environmentl temperture compred to egg weights for reeders housed in 15.5 nd 23 C. The reeders housed in 15.5 C my e explined either y the extr het 15.5 C tempertures produced eggs tht were increment of feeding or y n overestimted MEm. Therefore, in order to clculte the MEg, men efficiencies (kg) for the three groups of hens were used. Estimted kg in the present study (0.57) is 24% lower thn tht reported y Sprtt et l. (1990) for roiler reeder hens nd 10 nd 17.5% higher thn tht clculted y Rello et l. (2000, 2006). The vrition in these dt might hve een cused y the method used to determine protein nd ft ccretion rtes (respirtion clorimetry or comprtive slughter) (Wester, 1989). The estimted kg found in the present study my hve een influenced y ird ge nd vrition of ody composition within groups of roiler pproximtely 6.1 g lrger thn eggs for reeders housed in 30 C tempertures (Tle 4). The smller eggs for reeders housed in 30 C tempertures my hve een the reson tht the eggs from these reeders contined the lowest % yolk (DM), lthough nonsignificnt nd significntly lower % lumen (DM) (Tle 5). The non-significnt smller % yolk (DM) for the reeders housed in 30 C tempertures my hve lso een the reson tht the reeder eggs from this group contined significntly higher yolk % protein nd lthough non-significnt, highest yolk % ft (Tle 5). Breeders housed in 15.5 nd 23 C shown trend for producing eggs with n incresed % lumen (DM) 457

6 Tle 4: Performnce chrcteristics of roiler reeder hens mintined t 15.5, 23 nd 30 C during the lying period Tempertures ( C) Chrcteristics Egg weight, g ± ± ±0.93 Egg mss, g/hen/d ± ± ±1.90 Egg production, % ± ± ± Initil ody weight, kg 3.80± ± ±0.022 Finl ody weight, kg 3.84± ± ±0.022 Body weight chnge, g 31.85± ± ±11.30 Feed consumption ove mintennce, kcl/d 99.90± ± ±1.25, Mens ± SEM within vrile with no common superscript differ significntly (p<0.05) Tle 5: Egg composition, gross energy, prtil efficiency of egg synthesis nd ME for egg mss for roiler reeder hens mintined t 15.5, 23 nd 30 C during the lying period Tempertures ( C) Chrcteristics Averge Alumen, % 61.92± ± ± Yolk, % 29.28± ± ± Shell, % 9.41 ± ± ± Alumen DM, % ± ± ± Yolk DM, % 42.03± ± ± Alumen ft, % DM 0.05± ± ± Alumen protein, % DM 81.8 ± ± ± Yolk ft, % 56.59± ± ± Yolk protein, % ± ± ± Egg gross energy, kcl/g 1.67± ± ± ke 0.71± ± ± MEe , Mens ± SEM within vrile with no common superscript differ significntly (p<0.05) Tle 6: Body composition of roiler reeder hens Temperture ( C) Mesurement Initil First egg Finl Initil First egg Finl Initil First egg Finl Ft, % Protein, % DM, % Ft, % s DM Protein, % s DM GE, kcl/g Crcss composition of reeders t the eginning of the non-lying period. 2 Crcss composition of reeders t the end of the non-lying period. 3 Crcss composition of reeders t end of the lying period lthough the differences were not significnt etween ME needed per grm of egg mss (egg mss = EP x environmentl groups. Birds tht lid few or no eggs EW), the energy content of eggs ws divided y the during the lying period were excluded from the egg verge estimted ke, giving requirement of 2.3 kcl/g production nlysis ke clcultion. of egg mss. The Energy Content of Eggs (ECE) collected from roiler The ke s for roiler reeder hens housed t 15.5 nd t reeder hens housed t 15.5, 23 nd 30 C were 1.68, 23 C were higher (71 nd 79%, respectively) thn tht of 1.67 nd 1.65 kcl/ g, respectively (Tle 5). The energy hens housed t 30 C (66%), ut there were no vlue is sed on the entire egg weight including the significnt differences mong groups (p<0.05). shell. The verge energy content of reeder eggs from Breeders housed t 23 C were cple of sustining present study ws 1.67 kcl/g. The verge energy vlue reltively high egg production nd egg mss compred per g egg mss is similr to the generlly ccepted to the hens housed t 15.5 nd 30 C (Tle 4). Johnson NRC vlue of 1.66 kcl/g (NRC, 1981). The Energy nd Frrell (1983) concluded tht non-liner Content of Eggs (ECE) reported in literture rnge from reltionship etween retined energy nd totl ME 1.33 to 1.80 kcl/g (Skomur, 2004; Rello et l., intke from mintennce to production in roiler 2006; Sild, 1979; Chwliog, 1992). To clculte the reeder hens might explin the ke ove 70%. 458

7 Estimted vlues of ke reported in the literture rnge ws resumed. The use of TAM methodology mde etween 60 nd 86% (Skomur, 2004; Rello et l., 2006; Grimergen, 1974) depending on strin, ge, egg composition, egg size, lighting pttern, nutrition nd possile the use of the individul chrcteristics for estimting ME requirements nd voided the use of group verge vlue of MEm. The use of TAM lso environmentl fctors (Chwliog, 1992). High provided n dvntge of llowing the use of lrger efficiencies for egg production hve een oserved when roiler reeder hens use ody energy to compenste the energy shortge (Sprtt et l., 1990; Person nd Herron, 1981; Atti et l., 1995; Neumn et numers of individul reeders which would e difficult with indirect or direct metolic chmer clorimetric studies ecuse of the vilility nd costs of lrge numers of chmers. l., 1998) ecuse of the higher efficiency of using ody energy versus dietry ME for egg production. Although in the present study the men efficiency for EM synthesis (72.9%) is etween 60 nd 85% reported in the literture (Skomur, 2004; Chwliog, 1992), the vrition in ke vlues my indicte tht the het increment from the incresed feed llownce during the Prediction models for ME requirements for roiler reeders: The 3 equtions developed for predicting ME requirements for roiler reeders housed in different environmentl tempertures re s follows: Eqution 1: ME = BW [ T] + 5.8G + 2.3EM lying period my hve een used to help mintin the reeder ody temperture. The reduction in energy Eqution 2: 2 needed for MEm provided extr energy tht ws ME = BW [ T (T ) ] + 5.8G + deposited in eggs. 2.3EM In order to clculte the energy needed per grm of egg mss (egg mss = EP x EW), the energy content of Eqution 3: 2 eggs ws divided y the verge estimted ke, giving ME = BW [ T (T ) ] + BW) requirement of 2.3 kcl/g of egg mss (1.67/0.729). This (1/0.77 x Erf + 1/0.38 x Erp) + ECE/0.73 x EM vlue is in the rnge of 2.04 nd 3.13 reported in the literture for roiler reeder hens (Skomur, 2004; Rello et l., 2000; Leeson et l., 1973; Wldroup et l., 1976; Skomur et l., 1993; Byerly et l., 1980; Rello et l., 2006; Romero et l., 2009). The vlue 2.3 kcl/g of egg mss ws incorported into the prediction Where ME = Metolizle Energy (kcl); BW = Body Weight (kg ); T = Temperture ( C); BW) = Body Weight chnge (g/d); Erf = Energy retined s ft (kcl); Erp = Energy retined s protein (kcl); ECE = Energy Content of Eggs (kcl/g) nd EM = Egg Mss (g). equtions developed in the present study. Zhng nd Coon (1997) determined high ke in TAM ACKNOWLEDGEMENTS treted hens housed t tempertures of 15.3 C nd The uthors would like to cknowledge Co-Vntress, elow. The uthors suggested tht energy used for Inc. for finncil support nd for providing roiler reeder mintennce ws not totlly independent of the energy hens for the reeder studies. used for egg synthesis. Prt of the dditionl het lierted from the incresed feed intke during egg REFERENCES production ws used to compenste the MEm leving Atti, Y.A., W.H. Burke, K.A. Ymni nd L.S. Jensen, surplus of energy tht produced n overestimted ke for Dily energy llotments nd performnce of lying hens housed t cooler environmentl roiler reeders. 2. Femles. Poult. Sci., 74: 261- tempertures The present study supports similr conclusions drwn Boekholt, H.A., P. vn der Grinten, V.V. Schreurs, M.J. y Zhng nd Coon (1997) tht TAM cn e effectively Los nd C.P. Leffering, Effect of dietry utilized to stop egg production nd ccurtely determine energy restriction on retention of protein, ft nd MEm nd MEg in individul irds. Following short time energy in roiler chickens. Br. Poult. Sci., 35: 603- period for the nturl depletion of TAM, the efficiency of 614. utiliztion of ME for egg production nd MEe cn e Byerly, T.C., J.W. Kessler, R.M. Gous nd O.P. Thoms, mesured in sme individul hens. The use of TAMtreted roiler reeder hens in present study llowed the Feed requirements for egg production hens. estimtion of the coefficients needed for developing ME Poult. Sci., 59: prediction models. The estimted coefficients nd their Chwliog, A., Fctoril estimtion of energy vritions cn e otined from ech individul (unique) requirements for egg production. Poult. Sci., 71: reeder. The use of non-lying roiler reeders llowed more ccurte estimtion of MEm without interction Co-Vntress, Co 500 Broiler Breeder with EP nd lso provided n improved opportunity to mngement Guide. Co-Vntress, Silom estimte n ccurte vlue for ke when egg production Springs, AR. 459

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