Studies on the Development of Novel 305 day Adjustment Factors for Production Traits in Dairy Cattle

Transcription

1 689 Studes on the Development of Novel 35 day Adjustment Factors for Producton Trats n Dary Cattle K. H. Cho, S. H. Na, J. H. Cho, J. H. Lee and K. J. Lee, * Natonal Lvestock Research Insttute, RDA, Korea ABSTRACT : Ths study was conducted to develop a novel adjustment factors for 35 days usng 38,3 lactaton records and,77,764 daly records, whch were based on envronmental crcumstances such as herd year, season, age at calvng, dry perod and lactatng stages. The present study showed that the change of persstency of cows at the frst party from total lactactng characterstcs was slowly processed, whle t was rapdly changed n cows at the second party stage. Partcularly, there was an outstandng dfference between the frst and second party cows. Mlk yeld and composton ncreased as the age at calvng was ncreased. In addton, mlk yeld and composton were hgher at the frst party on fall compared wth others, and those were hgher at the more than second party on fall and wnter compared wth other party stages and seasons. The cow of dry group was ncluded nto lactatng records of more than second party stage. The data ndcated that optmal results arose from 45-7 days of dry perod. Mlk yeld was decreased when dry perod was longer or shorter than 45-7 days. The lactatng days were dvded nto 7, 8 and 38 stages to compare the multplcatve correcton factors. The factor was effectve at 8 stages on the frst party. The total correlaton coeffcents were.9383,.9558 and.9576 at the present correcton factor, 7 stage and 8 stage, respectvely. At second party, the factor was hgher n dry group and 3 at 7 stage, and t was hgher n dry group at 8 stage compared wth others. Therefore, the present study showed that the percent squared bas (PSB), whch was calculated from the novel correcton factor, was better than prevously used correcton factors. Also, the present study ndcated that the bas of the novel correcton factor was mproved, and ths factor could be more accurate compared wth others. (Asan-Aust. J. Anm. Sc. 4. Vol 7, No. : ) Key Words : Novel 35 day Adjustment Factors, Multplcatve, Correlaton Coeffcents, Percent Squared Bas (PSB) INTRODUCTION The 35 day adjustment factors for producton trats of dary cattle can standardze the dfferent mlk yelds due to dfferent mlkng days of ndvdual cows. These factors provde the opportunty of comparng mlk producng abltes and the bass for evaluatng the precse genetc abltes. If mlkng s n progress or ncomplete record are used by adjustng these stuatons earler, assumpton on the mlk producng ablty s possble and by progeny test the generaton nterval can be reduced as well. For that reason, a varety of nvestgatons and researches have been made for developng more precse adjustment factors on the producton trats of dary cattle. (Keown, 97; Danell, 98; Batra, 985; Wlmnk, 987ab; Khan and Shook, 996). Lee et al. (995) reported the frst adjustment factors whch are sutable for Korean dary cattle. It provdes a bass of standardzaton for dfferent mlk yelds of dary cattle and gves postve effects on cattle mprovement and also profts to dary farmers. The number of cows whch produce over, kg of mlk yeld, are stll ncreasng. In * Correspondng Author: K. J. Lee. Tel: , Fax: , E-mal: kjlee@konkuk.ac.kr Dary Cattle Improvement Center, N.A.C.F. Korea. Department of Dary Scence, College of Anmal Husbandry, Kon-Kuk Unversty, Hwayang-dong, Gwangjn-gu, Seoul, Korea. Receved March, 4; Accepted July, 4 tested cattle farms had over 8-kg mlk yeld and n 35 day test results were as follows: 8,76 kg total mlk yeld, mlk fat yeld 33 kg, mlk proten yeld 78 kg, and sold not fat (SNF) yeld 764 kg. In partcular, the ncreasng tendency of mlk yeld ndcated the enhancement of mlk yeldng abltes of dary cattle herd n Korea (Dary Cattle Improvement Center, N.A.C.F., 3). Hgh producton effcency n lvestock producton s an economcally desrable that targets ultmately for genetc up gradaton (Dhaka, ). Cows' mlk yeld ablty s dependent upon a varety of envronmental elements such as the mxng skll of feed, qualty enhancement, the development of feedng technques, the change of clmate due to the Greenhouse effect, and the party shft from mproved calvng ablty. In order to elmnate to elmnate these effects, new adjustment factors should be developed for predctng the precse 35 day producton trats wth ntervals. Ths s a good way to prevent the ever-changng envronmental elements, effectvely. Takng the tested data rangng from 999 to 3 nto consderaton, ths research llumnates the envronmental elements of age, delvery seasons, lactaton of dry perods, and to estmate the lactaton curves. Moreover, the adjustment factors on the bass of dvson of lactaton perods can be developed. By dvdng test data accordng to the lactaton perods, the adjustment factor can be attaned; ths research amed at fndng the relatonshp between exstng and new adjustment factors on actual 35

2 69 CHO ET AL. Table. Basc for varous varables Varables OBS Means SD Mn Max Party,77, Tno,77, Cumday 3,77, Mlk,77, Fat,77, Proten,77, SNF 4,77, Standard devaton, A tme of test day, 3 Cumulatve mlkng day. 4 Solds not fat, 5 Somatc cell scores. day accumulated mlk yeld, and developng the best adjustment factors for 35 day mlk yeld under current stuaton of Korean dary farmng. MATERIALS AND METHODS Materals Ths research deals wth the tested data collected by Dary Cattle Improvement Center, N.A.C.F. rangng 999 January to 3 January. Among the total 5,54,, 3 SD was restrctvely used for the records of mlk yeld and mlk components; party was lmted to the tenth; accumulated mlkng days were determned wthn 3 days, and the respectve records on lactatons are composed of,77,764 test records over eght tmes and 38,3 records on mlkng two tmes a day and the basc data shown on Table. Ths study was carred out usng the data from Dary Cattle Improvement Center, Natonal Agrcultural Cooperaton Federaton. Statstcal analyss In case of mlk yeld and mlk components, the lnear model s avalable to reveal the envronmental effect. By executng the analyss of varance (ANOVA) whch was sutable to the generalzed lnear model of SAS verson 8., the least square means can be ganed. Y jk = µ+hy +SAL j +e jk (I) Frst party Y jk = µ+hy +SADL j +e jk (II) Second party Where, Y jk s the observaton for mlk yeld and mlk component on the jk th cow. µ s overall mean. HY s the effect of herd-year, (I): (=,,...,,3) (II): (=,,..., 4,79). SAL j s the effect of the j th season of calvng-age-stage of lactaton of frst party (j=,,..., 4). SADL j s the effect of the j th season of calvng-age-drystage of lactaton of second party (j=,,..., 67). e jk s the resdual effect. RESULTS AND DISCUSSOIN Envronmental effects show meanngful dfferences respectvely n mlk yeld, mlk components and somatc cell count. Consderng calvng seasons, the results of producng more mlk yeld and components for fall and wnter group correspond to the cases n foregn countres (Tekerl, ). To nvestgate the party effect, all the party data were analyzed; n partcular dfference between the frst party and others was outstandng, so dfferent model methods were adapted between them. In the case of dry perods they were dvded nto four dfferent groups-under 45 days, 45 to Table. Least square means and standard errors for mlk producton trats and by age groups at frst and second party Age Mlk Fat Proten SNF Group LSM SE 3 LSM SE LSM SE LSM SE (3 ) (3<) (7 ) (7<) Solds not fat. Least square means. 3 Standard error. Table 3. Least square means and standard errors for mlk producton trats by season group at frst and second party P S Mlk Fat Proten SNF 3 LSM 4 SE 5 LSM SE LSM SE LSM SE Party, Season group, 3 Solds not fat, 4 Least square means, 5 Standard error. : Mar.-May, : Jun.-Aug., 3: Sep.-Nov., 4: Dec.-Feb..

3 STUDIES ON THE DEVELOPMENT OF NOVEL 35 DAY ADJUSTMENT FACTORS 69 Kg Frst party Second party Frst party, 3<, sprng Lactaton stage group (mlk) Kg, Days n mlk Fgure. Trends for mlk yelds by lactaton stage at frst and second party. 7 days, 7 to 9 days, and over 9 days. After operatng multple range tests on each of them, analyss of varance was taken. In sum, calvng age and seasonal effect on calvng are as followng n Table and 3. Takng seasonal factors nto consderaton, Keown (986) and Van Vleck (987) tred to prove the seasonal effects wth fxed effect model; Ko (989) estmated mlk yeld accordng to month and party by usng regresson n calvng year and season. It shows the seasonal effects between partes. As Syrstad (975) ndcated that calvng year and season had nfluence on mlk yeld, and fall and early wnter was the optmal season for calvng, and also the data from the frst party revealed mlk yeld and components of fall are recorded hghest; ths confrms that season has nfluence on mlk yeld. Also, n the second party, calvng seasons of fall and wnter show the hghest fgures n mlk yeld and components. Stages of lactaton were dvded nto three perods: early, md and late. Accordng to the lactaton methods, early lactaton ( to 9 days) shows the peak mlk yeld so that ths lactaton curve was dvded more specfcally nto 8 stages as a whole. From Fgure, as for stage of lactaton there s a dfference between frst party and second; as for mlk yeld there s a decreased nclnaton n stage 6; as for mlk fat there s consstence n the frst party, however, n the second party there s a decrease n stage 6. After the stage lactaton n the frst party earns more mlk yeld than n the second party. Ths phenomenon ndcates the stage of lactaton s mportant to envronmental elements regardng the dfference of mlk yeld accordng to the stages of lactaton. Thus ths shows the same result that persstency of lactaton n the frst party s hgher than n the second party but there s lower peak mlk yeld n the 7 stage 8 stage 38 stage 7 stage (95) Fgure. Comparson of resduals for the correcton factors by lactaton stages (3<). frst party (Keown, 97; Kellogg, 977; Schaeffer, 977; Shanks, 98). Dry mlk s the most mportant perod as a knd of preparaton perod n that t means the perod of storng nutrton factors for next lactaton, not the end of one lactaton perod by stoppng mlkng. Comparng the cows of no dry perod wth smlar herdmates of havng dry perod, smlar herdmate whch has a dry perod, t s reported that the former shows the decrease of mlk yeld (Remond, 997). Also, f a cow has too short dry perod and vce versa, mlk yeld was ncreased n Group shown on Table 4. Ths research shows that the optmal dry perod s between 45 and 7 days; whereas other approaches consdered the optmal perod 4 to 6 days (Coppock, 974) and 5 to 6 days (Jagannatha, 994). It s not advsable to have a short dry perod n Group, a short perod caused the least mlk yeld and mlk elements; otherwse t showed ncreased somatc cell count. The longest dry perod n Group 4 has the least mlk yeld. Ths result ndcates that long dry perod s related to the fact that shortened perod of lactaton means the decrease of mlk yeld so that t can affect reducton of ncome. In addton, the envronmental elements of mmunty have nfluence on ncrease and decrease of mlk yeld (Cho, 3); thus t s proved that age and season of calvng, and the stage of lactaton wll be the mportant elements. Ths research has tested the 45 to 9-day dry perod n Group, and dvded nto 3 groups because we cannot approve the varance of Group and 3. In Fgure, consderng the adjustment fgures of actual mlk yeld snce md lactaton, the comparson of random Table 4. Least square means and standard errors for mlk producton trats by dry perod groups at second party and above Dry Mlk Fat Proten SNF LSM SE LSM SE LSM SE LSM SE Dry group, Solds not fat, 3 Somatc cell count. : <45, : 45 dry<7, 3: 7 dry<9, 4: 9 dry.

4 69 CHO ET AL. Table 5. Correlaton coeffcents for corrected mlk yelds of the old and corrected mlk yelds by stages at frst party Lactaton perods (day) Records Old Novel Novel 7 stage 8 stage P value Total (-35), <. Early (-9) <. Mddle (9-4), <. Late (4-3) 7, <. Present correcton factor, The novel correcton factor due to ths study. Percent squared bas Percent squared bas Mlk, frst party Proten, frst party errors ndcates rather smlar results between stage 7 and stage 8, and less error than stage 38. The errors of the exstng adjustment factors are more than the novel factors and the errors of stage 8 are the least after over 3 months. Ths research took the data shown n sprng for the seasonal dstncton makes no dfference. Examnng the curve shft of adjusted mlk yeld by stages of lactaton the best adjustment appeared on stage day adjustment factors should be redeveloped perodcally and requre updatng at short ntervals. Adjustment factors for mlk, fat, and proten yelds by age and season of calvng were reestmated (Keown, 985). Ths study was usng the multplcatve method. The genetc trend from records wth multplcatve adjustment was substantally greater than addtve and optmal adjustments, especally durng recent years. Ageseason adjustment factors n the US have used a multplcatve rather than an addtve method. Addtve adjustments affect only means for age and season, but multplcatve adjustments also modfy varance n proporton to the square of the adjustment factors (Khan, 996). Multplcatve factors were calculated as ; Percent squareed bas. Percent squared bas Fat, frst party SNF, frst party Fgure 3. Comparson of old and novel correcton factor for percent squared bas between estmated and true 35 day yelds of producton trats at frst party. 8 S (LSM ) = = Y 35 S s the lactaton nterval days of the th lactaton stage. LSM s the least square mean of the th lactaton stage by age-season of calvng. Y 35 s 35 d mlk yeld. Ths method were reported reasonable to develop multplcatve factors because producton level was ncreased and relatonshp between mean and varance exst (Lee, 995). Test by makng use of correlaton coeffcent To test the accuracy of adjustment factors, lactaton records of actually over 35 days are examned. In general the lactaton nterval s dfferent accordng to the lactaton stages so we should dvde the lactaton perods. In proporton to the lactaton perods, 8 stages and 38 stages have the smlar lactaton stage, so that correlaton coeffcents n stage 7 and 8 are compared. In the case of the frst party, total correlaton s revealed to be.9383 wth old adjustment factors, whle novel factors showed.9558 and.9576 wth 7 and 8 stages, respectvely and thus the factors n stage 8 appears more accurate. Examnng the stages of lactaton, early to late lactatons showed hgher correlatons than those of old correcton factors (Table 5). However, n case of the second party, the dry group n 8 stages showed hgher correlatons, whle group and 3 n 7stages showed hgher correlaton. Investgatng the perods of lactaton, there s the same trend n the frst party but s more or less low correlaton coeffcents as a whole. That s the reason why ndvdual cows are adapted after the second party wthout adjustment between partes. In the case of the frst party, from Table 6 the novel adjustment factors for mlk yelds and mlk components showed hgher values than those of the prevous factors, when dvded accordng to the lactaton stages; the novel factors are proved to be more accurate. However, t seems somewhat complcated that the second party ncludes dry mlk groups. Wth or wthout the dry mlk group, there s no dstnct dfference between lactaton perods. Ths suggests more precse adjustment methods are needed.

5 STUDIES ON THE DEVELOPMENT OF NOVEL 35 DAY ADJUSTMENT FACTORS 693 Percent squared bas Test by makng use of percent squared bas PSB Mlk, second party, dry group n Percent squared bas = = n 3 (EŶ TY ) = TY where, EŶ = estmated 35 day yeld. TY =actual 35 day testday yeld. =the th test. n=the total number of test. Ths fgure shows the dfference between actual amount of mlk and presumptve one. In other words, the more dfference of PSB (percent squared bas) t has, the more t has the bas between currently used adjustment factors and newly mproved ones. Owng to the realstc dffcultes, ths research has used test day mlk yelds, not everyday 35 day mlk yeld. That s, PSB puts test number nstead of test mlk yeld and respectve lactaton perods. In the case of frst party as shown n Fgure 3, the ncrease of lactaton, e., test number and the decrease of PSB corresponds to the results of Archer (994). There s a great deal of dfferent bas n mlk components; ths suggests the optmacy of the novel adjustment factors. In the second party, only the mlk yeld s presented and dry Group, whch has the least bas, shows the best adjustment accordng to Fgure 4. In the second party, only the mlk yeld s presented and dry Group, whch has the least bas, shows the best adjustment accordng to Fgure 4. Percent squared bas Mlk, second party, dry group 3 Mlk, second party, dry group Fgure 4. Comparson of old and novel correcton factor for percent squared bas between estmated and true 35 day mlk yelds at second party. CONCLUSION For the past years, the contnual mprovement of dary cattle n Korea has brought the remarkable enhancement of producton trats. In ths respect, ths research has nvestgated the envronmental effects on age, calvng season, lactaton perod and dry; besdes, dvdng test records accordng to the lactaton stages, we can develop the novel adjustment factors. The stage 8 was the best adjusted stage of lactaton regardng to the actual 35 day mlk yeld. Consderng the correlatons between exstng adjustment factors and novel adjustment factors, and the PSB on the actual 35 day mlk yeld, novel multplcatve adjustment factors are the most sutable to the contemporary dary cattle herd n Korea. Wth ths research the newly-developed 35 day adjustment factors, acqured by use of the stages of lactaton, are expected to help dary management and ncrease dary profts n that the factors can be used for enhancement of productvty by managng dary cattle effectvely. Besdes, more precse genetc evaluaton on the cows that are mproved genetcally can be expected and t can play an mportant role to develop progeny test programme; by selecton for superor sres and elte cows on the bass of accurate evaluaton on productve ablty t may be avalable for the effectveness and development of dary cattle breedng. The nformaton on the data of 35 day adjustment factors s presented on the webste ACKNOWLEDGMENT Ths study was partally funded by Rural Development Admnstraton specal grants research program n Korea. REFERENCES Archer, A. A Multple trat method to estmate 35 day lactaton yelds for Holsten dary cattle. Unversty of guelph, Can. Batra, T. R. and A. J. Lee Comparson of three methods of predctng 35 day mlk and fat producton n dary cows. Can. J. Anm. Sc. 65: Coppock, C. E., R. W. Everett, R. P. Natzke and H. R. Ansle Effect of dry perod length on Holsten mlk producton and selected dsorders at parturton. J. Dary Sc. 57:7. Cho, J. G., K. J. Jeon, C. W. Na, J. B. Km and C. Lee. 3. Trend n hertablty of dary mlk yeld by perod n Korean cattle. Asan-Aust. J. Anm. Sc. 6(9):39-4. Dhaka, S. S., S. R. Chaudhary, B. L. Pander, S. A. Yadav and S. Sngh.. Genetc studes on producton effcency trats n Harana cattle. Asan-Aust. J. Anm. Sc. 5(4): Jagannatha, S., J. F. Keown, L. D. Van Vleck and A. J. Lews Effects of days open, days dry, and season of freshng on ncome over feed cost and 35 day mature equvalent mlk yeld, for three dfferent producton levels. Unted States

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