Supplementary feeding of dairy cows : a study of the value of greenfeed maize as a summer supplement : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University

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(2) SUPPLEMENTARY FEEDING OF DAIRY COWS. A Study of the Value of Gree nfe e d Maize as a. Summe r Supplement. A. Thesis. Presented in Partial Fulfilment of the Requirements For the Degree. of. MASTER OF AGRICULTURAL SCIENCE. in ANIMAL SCIENCE. at. MASSEY UNIVERSIT Y. THOMAS. J.. 1 977. KIRLEY.

(3) ii. ABSTRACT. An experiment is described in which the n ut ritive value of greenfeed maize as a supplem en t to lactating dairy cows during the Summer dry period was in vestigated. F orty Spring calving Friesian cows were allocated to one of hio treatments in a randomised block design experimen t. of 20 cows was fed on grazed pasture a lone 7.96 ha farmlet while the other group of. 20. ( c ontrol ). On e group. on a separate. cows was fed a supplement. of greenfeed maize in addition to the pasture from a 7.75 ha farmlet. The farmlets of both groups were divided in to 7 paddocks and the cow8 were rotation ally grazed. followed by a. 5. A. 1. week standardisation period was. week experimental period.. The herbage present on both farmlets was estimated at the beginning of the experiment and1during the experiment, estimates of of the pasture remain ing after grazing were m ade which gave an indication of the grazing in ten sity.. Tvro crops of greenfeed maize vrere fed, Crop A and Crop B. Crop A had a low· y ield of D M , poor plan t den sity and a high weed po:pulation.. Crop B had a high plan t population with thin stalks. and fevr weeds. Mean daily milk,. milk fat, m ilk protein y ields and liveweights. were �ot sign ifican tly differen t between groups.. There were. sit�nifican t differen ces between the slopes of the regression. l:i.nJs relating pretrial to expe rimenta l milk yields m ilk protein yield. ( P< 0.05 ). s its:1ificant differences. of the two groups.. (P < 0 . 1 0 ). (P < 0 .01). and. There were. between the slopes of the. regression lines of milk y ield against tim e of the two groups and behreen the lovr yielders. of each group but no significan t difference behmcn the high yielders of e ach group.. The con trol group m aintain ed their liveweight during the first half of the trial an d lost weight in the second half of the t rial. The naize group lost weight initially then increased steadily in live\veight .. However,. the differences in mean liveweight between. groups were not statistically significant..

(4) iii. The hich yie lde rs lost more we ight in the se cond half of the t rial than the low yie lde rs in the con trol group.. It. while the ove rall diffe rence s in the. \'l"Ould appear that,. me:1n daily milk yields between groups were. too small to be. the milk yie ld of the con trol group. statistically significan t,. decline d at a faste r rate than the maize group with the low yie lde rs in the control group de clin ing at the faste st rate .. The we ight. los·: by the high yie lde rs in the control group was slightly grea te r tha:1 that of the lOi'l y ie lJ.e rs in the same group.. The high. yielde rs in the c ontrol group main tain e d the ir rate of de cline in m ilk yield similar to that of the supple men te d group an d this vras prob9.bly achieve d by a gre ater re duction in live weight re lative to t�e low yie lde rs. The yie ld of Crop B vlas va.ried from. 7 1 . 2 - 7 5 .4 %. Mi cow/day. ke/n. 1 1 , 008. kg D M. of the 0 M. and utilisation. 76.5. /ha. and the digestibility. Maize intake was. .. an d. 82 . 1 %. of the D M. 3.0. an d. ).�. for. Crops A and B re spective ly. The contro l group comple te d two rotations on the ir farmlet witit rotation lengths of. 19. and12 days,. At the end of the e xpe riment. they we re very short of p9.sture .. The maize group had c omplete d one. rot:-;.tion in 26 days and had graze d. 1.1. ha for a se cond time.. They. had ade quate supplie s of he rbage at the en d of the expe riment. Supplementation with greenfe ed m9.ize pe rmitte d the adoption of a longe r rotation length, a better distri bution of the available pasture ove r the Summe r pe riod and slowe d t he rate of declin e in milx yield in the suppleme nte d group.. \.

(5) iv. A CKNOWLEDGEMENT S. The author wishes t o exp re s s hi s d e ep gra t i t ude t o h i s s upervi s or D r . A . W . F. Davey for invaluable guidanc e and a s s i s t an c e i n a ll asp e c t s of t he s t udy .. Si ncere thanks are als o ext ended t o the f ol l owing :. P r ofessor D . S .. Fl ux and D r . G . F . Wi l son. D epartment. ). ( Dai ry. for the i r a s s i s tanc e and a dvi c e .. Me:J:c:rs G . Juke s , N . M c Lean and R. Mc C l eneghan Department Mr � . Hughe s. ). Hus bandry. ( Dairy. Hus bandry. for their s ki l l e d t e c hn i c al as s i st anc e .. ( f ormer. Pos t-graduat e stud ent. ). for h i s a s s i s tan c e. o n many oc cas i ons . Mr R. Halford Mr D. Baggott No .. 1. ( Farm. ( Farm. ). Land s Sup erv i s or .. Manager No .. 1. Dai ry Farm. D �iry fa rm who made tho anim�l a ,. ). and the s taff of. lnnd and fa c i l i t i e s. avsila bl e and who as s is t ed i n the d a y t o day running o f the erperiment .. Mr R . Sims. ( Agrono�y. Department. greenfeed mai z e crop. ( Crop. ). f or p e rmis s ion t o use a. ). B in text .. The Town Milk Produc ers Fede rat i on who p r ov ide d financ ial support. t() Mas s e y Univ e rs i t y. :Which. enabl ed t h e study to t ake p l ac e .. The Iri sh D epa rtme nt of A gricul ture who supp ort ed me fi nanc i al l y during t h e perioi o f my Mas tera t e Stud i es . M is:> Judy M c Ke gg for he r s ki ll e d typing of t he final c opy of this thezi s . Fina l ly, very spe c i a l thanks are due t o my wife, Mary, and famil y f or their pati ence , unde r s tandi ng and support thr oughout the s t udy..

(6) TABLE OF CONTENTS. A BSTRACT. ii. ACKNOiriLEDG E�1ENT S. iv. LIST OF TABLES. ix. LIST OF FIGURES. xi. LIST OF PLATES. xi i. LIST OF APPENDICES. xiii. CHAPTER I The Supplementary Feeding of Lactating Dairy Cows -. A Review of Literature. 1 .1. Introd uction. 1.2. Supplementary Feeding of Grazing Dairy Cows. 1 . 2.1. Supplementary Feeding w hen the Supply of Grazing Herbage is Adequate. 1 .2.2. Supplementary Feeding when the Supply of Grazing Herbage is Inadequate. 1 . 2.2 . 1. 1.2 . 2 . 2. 7. Concentrates as the Supplementary Feed. 7. Roughages as the Supplementary Feed. 1 . 2.3. 2. 11. Responses of Grazing Cows to Supplementary. 12. Feeding. 1.2.3 . 1. Substitution. 1 . 2. 3 . 2. Responses to Supplementary Feeding when Grazing Supply is Adequate. 12. 12.

(7) 1 .2.3.3. Responses to Supplementary Feeding when. 14. Grazing Supply is Inadequate. 1.3. Supplementary Feeding of Cows Fed Hay and Silage. 14. As the Basal Ration. 1 3. 1 •. Types of Supplements Fed to Cows on Basal Rations of Conserved. Pasture Horbaeo. and. Responses from Feeding. 1 3. 2 •. 15. Factors which P5fect the Responses of Cows Fed Conserved Pasture Herbage Ad Lib to Supplementary Feeding. 1. .4. Maize as a Supplementary Feed for Lactating Cows. 23. 1.4.1. Supplementary Feeding v1ith Maize Silage. 23. 1 4. 2. Supplementary Feeding with Greenfeed Maize. 26. •. 1.5. 21. Objectives of the Experiment and Choice of Design. 27. CHAPTER I I Material s and Methods. 30. 2.1. Experimen tal Animals. 2.2. General Outline of the. 2.3. Experimental Feeds and Feeding. 32. 2.3.1. Grazing System. 32. 2.3.2. Greenfeed Maize. 32. 30 Experiment. 30.

(8) Page. 2.4. Experimental Procedur e s. 37. 2.4. 1. Yield and S t a ge of Maturity of t he Ma iz e Crops. 37. 2.4.2. C hemical C omposit ion of Maiz e and Pasture. 37. 2.4.3. Digestibil ity of Maiz e and P a s t ure. 38. 2.4.3.1. In Vitro Dige s t ibil ity of Maize and Pasture. 38. 2.4.3.2. In Vivo Dige s t ibilit y of Maiz e C r o p B .. 38. 2.4.4. 2.5. Pas ture Availability and Graz ing Intensity. 39. 2.4.5. Maiz e I ntake and Ut il is a t ion. 39. 2.4.6. Milk Yield ,. 40. C ompo s it i on and L ivewe ight C hanges. Stat is t ical Analysis. 41. 2. 5. 1. Preliminary Analysis of the Data. 41. 2.5.2. Statist ical Ana lysis of Milk , Milk fat and Milk Pro t e in Yields , a nd Liv e vreight C hanges. 41. C HAPTER III. 42. Results. 3. 1. Gene ral De scription o f t he Maiz e Crops. 42. 3.2. C hemical Ana lysis of Maiz e and Pas tu re. 42. 3.3. Dige s t ibility of Maiz e and Pas ture. 42. 3.3.1. In Vit ro Dige stibil ity of Maiz e a nd Pasture. 42. 3.3.2. In V i vo D ige s t ib il it y of Maiz e and Pas t ure. 42. 3.4. Pas ture Availability and Grazing Int ens i ty. 50. 3.5. Maiz e Int ake and Utilis a t io n. 50. 3.6. Milk Yield,. •. •. .. C o mpo s it ion and Liv ewe ight Changes. 54. 3.6.1. Milk Yie l d. 54. 3.6.2. Milk C o mposition. 62. 3.6.3. Liveweight C hanges. 67.

(9) C HAPTER IV Discussion_. 70. 4. 1. Yi e ld of M aize Crop. 70. 4.2. Nutrit ive Va lue of Mai ze. 72. 4.2.1. C hemi cal C ompos i t i on. 72. 4.2.2. Di ge s tibi l i t y of Gr eenfeed Maize. 72. 4.3. Intake of Greenfeed Mai z e. 76. 4.4. Re s ponse t o Supplemen tary Fe eding of Greenfeed M ai ze. 78. 4.5. Pra c t i cal C ons i dera t i ons. 82. 4.6. C onc lusi ons. 83. APPENDIC E S. 84. B I BLIOGRAPHY. 99.

(10) LIST OF TABLES PAGE T:\JLE. --·-. 1 o1. EFFECT OF LEVEL OF CONCENTRATE FEEDING ON MILK YIELD OF SPRING CALVING COWS AT PASTURE. 1 o2. (GORDON. 1 974 ). 4. SUMMARY OF EXPERIMENTS IN WHICH COWS, vJITH ADEQUATE SC'FPLIES OF PASTURE HERBAGE vlERE FED SUPPLEMENTARY. 6. CONCENTRATE FEEDS.. 1o3. RESPONSE TO CONCENTRATE FEEDING, STOCKING RATE. AND CALVING DATE (ADAPTED FROM HUTTON AND PARKER. 1 967 ) 1otl-. 9. 0. SUMMARY OF EXPERIMENTS IN vrHICH CO\vS vTITH INADEQUATE SUPPLIES OF PASTURE HERBAGE \vERE FED SUPPLEMENTARY. 10. CONCSNTRATES.. 1. o5. IULK YIELDS AND D M. FEEDING LEVELS,. INTAKE OF COWS. FED CONCENTRATES AS SUPPLEJVT.:SN'l'S TO PASTURE SILAGE AD LIB. 1 o6. 1971 )o. (GLEESON. 16. POST CALVING CONCENTRATE FEEDING,. SILAGE D M. INTAKE,. MIIJ <: YIELDS, LIVE'ifEIGHT CH..I1.NGES AND RESPONSES TO S�TPLEMENTATION PER COW OF CO#S FED SILAGE AD LIB (ADAPTED FROM GLEESON. 1 o7. 1973 ). 17. MILK YIELDS OF AUTUMN CALVING COWS FED THREE LEVELS OF CONCE NTRATE SUPPLEME N'l'ATION AND SILAGE AD LTB (GL�ESON. 1o8. 20. 1973 ) o. INTAKES O F D M. ,. D E. AND MILK YIELDS O F GROUPS OF. CO"i!S FED PASTURE SUPPLEMENTED WITH MAIZE SILAGE AND ?1\S!.'iJRE SILAGE. 2o1 3.1 3o2 3 .3. (ADAPTED FROM BRYANT AND DON NELLY. 1974 ) o. PLAN OF EXPERIMENT PHYSICAL CHARACTERISTICS OF MAIZE CROP B. AS FED CHEMICAL COMPOSITION OF MAIZE. (D M. CHEf'1ICAL COMPOSITION OF PASTURE. BASIS). (D M. BASIS).. IN VITRO DIGESTIBILITY OF MAIZE (0 M. BASIS).. 3 .4 3o5. IN VITRO DIGESTIBILITY OF PASTURE (0 M. 3o6. IN VIVO DIGESTIBILITY OF MAIZE CROP B. 3 o7 3o8. PASTURE AVAILABILITY AT THE BEGINNING OF THE EXPERIMENT. BASIS). (0-M. BASIS). 24 31 43 44 45 46 48 49 51. :?ASTURE REMAINING AFTER GRAZING BY THE T\ifO GROUPS. OF. CO.NSo. 52.

(11) TI\I�LE. 3.9 MAIZE INTAKE AND UTILISATION 3 . 1 0 MEAN VALUES FOR DAILY MILK YIELD (1) OF TWO GROUPS OF COWS 3 . 11 ��VALUES FOR DAILY MILK YIELD (1) OF HIGH YIELDERS Ai'IJD 3.12. LOW YIELDERS OF. 2. MEP� VALUES FOR DAILY MILK FAT YIELDS (g) A�� FAT. 3.:3 MEAN VALUES FOR DAILY MILK PROTEIN YIELDS (g). 63 AND. PROTEIN CONTENT OF TWO GROUPS OF COWS. MEAN VALUES FOR LIVEitlEIGHTS. 65. (:kg). 68. OF TvlO GROUPS OF COilS.. 4.1. 55 59. GROUPS OF CO\ifS.. CO�TENT OF T'�TO GROUPS OF COilS.. 3.14. 53. �WNTHLY RAINFALL. ( mm) DURING SUMMER 1 97 5 /76. AND. C0l1H)ARISONS WITH 5 YEAR AND 30 YEAR AVERAGES (DATA SUPPLIED BY. 4 .�:. D.S.I.R. PALMERSTON NORTH).. DIGESTIBILITY OF GRESNFEED NAIZE (0 r1. BASIS).. CON?ARISONS BET'tlEEN THIS STUDY AND PUBLISHED VALUES.. 4 o3. COMPARISON OF IN VIVO MAIZE. AND. 71 73. IN VITRO MEASURENENTS OF. SILAGE ( HARRIS 1 963 ).. 75.

(12) LIST OF FIGURES PAGE. 1.1 RATE OJ<,PAS·rURE GRO.N'TH (CUMBERLAND 1974). 27. 2.1. MAP OF NO. 1 DAIRY FARM.. 33. 3.1. �JIEAN DAILY MILK YIELD DURING PRETRIAL. AND. 56. EXY��UJVIENTAL PERIODS. 3�2. THE RELATIONSHIP. BET'dEEN. PRETRIAL. AND. EXPERHJIENTAL. 57. MILK YIELDS. 3 .). 'l'liE RELA'riONSHIP BET\,TEEN EXPER HlEN TAL MILK AND. 3.4-. 58. TIME.. MEAN DAILY MILK YIELD DURING PRETRIAL EA'TE�UMENTAL PERIODS OF HIGH HT. 3 .5. 3oG. YIELD. A..TW. AND. LOW YIELDING COWS. 60. EACH G:?:.OrJP.. RET,A'riONStHP. BET\,TEEN TlfiLK YIE L D AND TIME. LO\v YIELDERS. IN TVlO GROUPS.. MEA.l'i[ DAILY FAT. YIELD S. FOR. HIG-H. AND. (g) .�.ND FAT % DURING PRETRIAL. 64. AND EXPERIMENTAL PERIODS. 3.7. MEAN DAILY MILK PROTEIN YIELD. (g) AND PROTEIN%. DURING PRETRIAL AND EXPERIMENTAL PERIODS. 3.8. LIVEWEIGHTS AND LOW. 61. 66. (kg) OF TWO GROUPS OF COWS AND HIGH. YIELDERS. IN EACH. 4.1 D M INTAKE REQUIRED. BY. GROUP.. 69. MAIZE GROUP OF COWS DURING. THE EXPERIMENT (CALCULATIONS BASED ON M.A.F.F. 1 97 5 ) .. 77. 4.2 SIMPLIFIED MODEL TO DESCRIBE THE RELATIONSHIP OF FOOD TO MILK AND LIVEWEIGHT IN DAIRY COWS ACCORDING TO RESPONSES TO LEVEL OF INTAKE (FROM BROSTER 1 976).. 80.

(13) LIST OF PLATES. PLATE. 2.1 2.2. 35. GREENFEED MAIZE CROP B . GREENFEED MAIZE STRIP,. CUT WITH MOWER,. FEEDING.. 2. 3 2.4. FEEDING OF GRESNFEED r-lAIZE. REFUSALS OF GREENFEED MAIZE.. PRIOR TO. 35 36 36.

(14) LIST OF APPENDICES. PAGE. APPENDIX. I II III IV. DETAILS OF GREENFEED ��IZE CROPS. 84. EXPERTI1SNTAL COI'lS. 85. IN. 86. VIVO DIGESTIBILITY OF GREENFEED ��IZE. ANALYSIS OF MILK YIELD DATA. 94.

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