Factors affecting the response of dairy cows to once daily milking : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University

private study only. The thesis may not be reproduced elsewhere without

the permission of the Author.

i

FACTORS AFFECTING THE RESPONSE O F

DAIRY CO�S TO ONCE DAI LY MI LKING

A t he s i s p r esen t ed i n par t i al f u l f i lmen t o f the requi remen t s f o r t h e degree o f

Maste r o f Ag r i cu l t u ral Scien ce i n Animal S c i ence

at Mas sey Unive r s i ty

MARGARETH ROBERT NJARITTA

1 9 8 9

AB STRACT

The a i ms o f th i s study was to evaluate the e f fect o f once d a i ly m i l k i ng du r i ng m i d - lactat i on and to i d e nt i fy fa cto rs wh i ch could be u s e d to pred i ct.the res ponse o f d a i ry cows m i lked once d a i ly. Facto rs stud i ed i n c l uded i ntramamma ry pressure ( I MP ) , u d d e r volume , res i dual m i lk and m i lk compos i t i o n . A total o f 3 2 F r i es i an cows , s i xteen h i gh breed i ng i ndex ( HBI ) and s i xteen low breed i ng i nd ex ( LBI ) ( 2 - 1 1 years o l d ) w e r e used i n t h e study . With i n e a c h breed i ng i nd ex grou p , cows were f u rther d i v i d ed i nto 2 grou ps, cows were then allocated to e ither once d a i ly m i l k i ng (treatment grou p ) o r tw i c e da ily m i l k i ng (control grou p ) s o the groups were balanced for b reed i ng i ndex and age .

The expe r i mental pe r i od was d i v i d e d i nto 3 ma i n pe r i od s , a p r e -t reatment ( 3 weeks ) , a treatment (3 weeks ) and a po st-treatment pe r i od ( 7 weeks ) . Du r i ng the p r e -treatment period I M P ( be fo r e mo r n i ng and a fte rnoon m i lking), empty udder volume a fter mo r n i ng m i lk i ng , res i dual m i lk and peak f low r a t e were measured . Dur i ng the treatment pe r i od i ntramammary pressure was meas u red at 1 5 h r , 20 h r and 24 h r a fter m i l k i ng . Du r i ng the f i rst three days o f the post-treatment pe r i od I M P was measured b e f o r e a fte rnoon m i l k i ng and udd e r volume a ft e r a fte rnoon m i l k i ng were measured .

measured d u r i ng the who le pe r i od .

M i lk y i eld and compos it i on w e r e

1 ) On ave rage o n c e da i ly m i l k i ng reduced d a i ly y i elds o f m ilk , f at , and p rote i n by 2 . 8 kg/cow ( 19% ) , 0 . 08 kg/cow ( 1 4% ) and 0 . 08 kg/cow ( 1 6% ) res pecti vely i n compar i s on

w ith the contro l g roup .

2 ) F o llow i ng c e s s at i on o f the treatment , the ave rage da ily

iii

p roduc t i on o f cows prev i ou s ly m i lked once d a i ly was 1.1 kg ( 7% ) m i lk , 0.06 kg ( 9% ) f a t , 0.02 kg (4 )

l a c t o s e l e s s t han t h a t o f the con t rol group .

3 ) The d e c rease i n m i lk y i e l d f o r t h e i n d i v i d ual cows over t he t rea t men t p e r i od ranged f rom 1 2% t o 46% .

4) The concen t ra t i on o f f a t and p r o t e i n i n c reased wh i le t h a t o f lac t o s e dec reased dur i ng t he t r ea t men t p e r i od i n cows m i l ked once da i ly .

5) Measur emen t o f the m i lk y i e ld and m i l k i ng t i mes were n o t

s u f f i c i en t ly p re c i s e t o a l l o•; t h e calcula t i ons o f r e sidual milk by a novel me t hod .

6 ) There was a s i gn i f i can t rela t i onsh i p be tween I MP 1 5 h r a f t e r p r e v i ous m i l k i ng ( P < 0.05) and the d e crease in m i lk y i eld due t o once dai ly m i lk i ng .

7 ) The r e s ponse t o once da i ly m i l k i ng was no t rela t ed t o o t h e r f a c t o rs such as IMP a t 20 h r and 24 hr a f t e r m i lk i ng , udd e r vo l ume o r

m i lk f low .

Po s s i b le reasons f o r t he fai lure o f t h e s e fac t o r s t o p r ed i c t t he r e s ponse o f cows t o once d a i ly m i l k i ng are d i s cu s s ed.

I t i s concluded t h a t fur t he r s t ud i e s are needed to i nc rease our unde r s t an d i ng of the con t r i bu t i o n of r e s i dual m i lk to t h e phys i cal and chem i cal i n h i b i t i o n of m i lk s e c r e t i on .

ACKNO�LEDGEHENT

I would like to give s pecial thanks and apprecia tion to my supe r vis o rs , Drs D . D . S . Macken zie , C . � . Holmes , H . T . Blai r fo r t heir guidance , h e l p and pa tience bo t h d u ring the expe rimen t a l work and p r e para tion o f

t his t he sis . I wou l d also wish t o thank the following p e o pl e :

The s t aff of t h e Dairy Ca t t l e Research Uni t for t heir a s sis t an c e in conduc ting the expe rimen t .

G r a ti t ude is e x t ended t o Harga r e t S co t t for h e r h e l p in ana lysing t h e mil k samp l e s .

I a p p r e cia t e v e ry much the inval uable h e l p and encou rageme n t given t o

me by the fo l lowing f e l l ow s t uden ts: Ha ria Da t t ena , Valen tini Rugambwa , Noel Sembuli , Carlos Sosa and Hin Hong Seo k .

The New Zealand Govermen t f o r the Schola rship t h a t a l l owed m e t o c a r ry o u t my s t udies .

The Tanzanian Goverme n t for a l lowing me t o s t udy in New Zealand .

Fina l ly , special thanks t o my mo t he r , bro thers and sis t e r s f o r t aking care of my child ren while I was s t udying .

\

V

TABLE OF CONTENT S

TITLE PAGE . . . i

AB STRACT ^{. . .. . . . . . .. . . . . .. . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . .. .}i i ACKNOiJLEDGEMENTS . . ^{. . . .} .^{. . . . .} . ^{. . . . . . .. . . .} . ^{. . .} . ^. .^{. . . .} . . . .^. . . . .^. . i ^V TABLE O F CONTENTS ^{. .} . ^. .^{. . . . .} . . . .^{. .}. ^{. . . .} . ^{. .. . . . .} . ^. . . ^. . .^. . ^{. .}. ^. . ^{. v}

L I ST O F TABLES . . . i x L I ST O F FIGURE S . . . x i 1 I NTRODUCTION ^{. . . . .. .} . . . ^{. .} . ^{. .} . ^.. ^{. . . . . . . ..} . . ^{. . . .} . ^. .^{. .} . ^{. . .} . . . . ^{. . .} . 1

2 REV I EiJ O F LITERATURE ^{. .. . . . . . . . . . . . . . . .. .} . ^{. . . . .} . .^. . ^{. .} . ^{. . . . . . .} . . 3

2 . 1 E F FECT O F M I LKING FREQUENCY ON M I LK YIELD AND COMPOSITION ^{. .}. ^{. . . . .. . .} . . ^{. . . . . .. . . . . . .} . ^{. . .} . .^{. . . . .} .^{. . . .}. ^{. . . .}3

2 . 1 . 1 Th r i ce Dai ly M i l k i ng . ^. . ^{. .. . . .} . . ^. . ^. . ^{. .. . . . . . . . . . .} .^{. . .}3

2 . 1 . 2 Tw i ce Da i ly M i l k i ng . . . 4

2 . 1 . 3 M i l k i ng Three T i mes i n Two Days . . ^{.. . . . .}. ^{. . . . . . . .} . . . ^. 7

2 . 1 . 4 Once Da i ly M i l k i ng ^{.. . . .} . ^{. . . . . .. . . . .} . . ^{. . .. .} . ^{. . . . .} . . ^{. .}7

2 . 1 . 5 M i s s ed M i l k i ngs . ^{.. . . . .} . ^{. . . . . . . . . .. . . .} . .^{. .}. . ^. . ^. . ^. . ^{. . .}8

2 . 2 EF FECT O F M I LKING FREQUENCY ON BODY iJE IGHT . . . ^{. . . .} . . . ^. . . 1 0 2 . 3 EFFECT OF MI LKI NG FREQUENCY O N UDDER HEALTH ^{. .}. ^{. .} . . ^{. . . . . .} .^. 1 2 2 . 4 M I LK DI STRIBUTION AND REMOVAL . ^{.. . . . . . . . . . .} .^. . ^{. .} . . ^{. . . .} . . .^{. .}1 4 2 . 4 . 1 D i s t r i b u t i o n o f M i lk i n t h e Gland ^{. .} . .^{. . . .} . . . . ^{. .} . . .^{. .}. 1 4 2 . 4 . 2 M i lk Ej ec t i on ^{. .. .} .^. . ^{. . . . .. .} .^{. . . . . .} . ^{. .} . ^{.. .} . ^{. . . . . .} .^{. .} . ^. 1 5 2 . 4 . 3 Fac t o rs A f f e c t i ng M i lk F low Ra t e . . ^{. . .. . . . .} . ^{. .} . .^{. . . .}. . 1 5 2 . 4 . 3 . 1 M i lk Y i e l d and I n t ramammary P r e s s u r e . . . 1 6 2 . 4 . 3 . 2 Tea t O r i f i ce D i ame t e r ^{. . . .. . .} . . . . ^{. .} .^{. . . . .} . . . ^{. .}1 7 2 . 5 FACTORS AFFECTING THE RESPONSE TO VARI ATION I N M I LKING FREQUENCY ^.. . . ^{. . .} . . .^{. .} . ^{. . . .} . . .^{. . .} . ^{. .} . ^{. . .. . . . .} . ^{. . .} .^. . . . . ^{. . . . .} . 1 8 2 . 5 . 1 I n t ramammary P r e s s u r e and Udd e r Volume ^. . . .^. . . . ^{. .} . . . ^{. .} . 1 8 2 . 5 . 1 . 1 Changes i n I M P be tween M i l k i ngs . .^. . ^. . ^{. . .} . ^{. .} . . ^. 18

2 . 5 . 1 . 2 E f fec t o f I M P on M i l k Secre t i on . . . 1 9 2 . 5 . 2 Ud d er Volume . . . 2 1 2 . 5 . 3 Udd e r Produ c t i v i ty . . . 2 1 2 . 5 . 4 Res i dual M i lk Y i eld . . . 2 2 2 . 5 . 4 . 1 M i l k i ng Frequency and Amoun t o f Res i dual M i lk . . 2 3 2 . 5 . 4 . 2 M i l k F low Ra t e s and Res i dual M i lk . . . 2 3 2 . 5 . 4 . 3 The I n t ens i t y and Dura t i on o f M i lk Ej e c t i on . . . . 2 4

2 . 6 THE MECHANI SM B Y VHICH MI LKING FREQUENCY INFLUENCES M I LK

PRODUCTION ^{. . . . . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . .. . . . . .. . . . . . .}2 5

2 . 6 . 2 Chemi ca l 2 . 6 . 3 Ho rmonal 2 . 6 . 3 . 1 2 . 6 . 3 . 2 2 . 6 . 4 Mammary

v i i

3 . 4 . 5 M i lk Y i eld and Composi t i on . ^.. . ^. . . . ^. . .^{. . . . . . . . . . . . . .}3 9 3 . 4 . 6 B ody Ve igh t and Condi t i on Score ^{. . .. . . . . . . . .. . . . •. . .}40 3 . 4 . 7 Soma t i c Cell Coun t . ^{. . .. . . . . . . .. . . . . . . . . .. . . . . . . . . . .}41 3 . 5 S t a t i s t i cal Analys i s ^{.. . . . . . .. . .} . . . ^. . . ^{. . .. . . . . . . . . .. . . .} . ^{. . . . .} 4 1 4 RESULTS ^{. . . . . . . .. . . . . . . . .. . . . . . .. . . . . . . .. . . . . . . .. . . . . . . . . . . . . . .}45 4 . 1 P r e t rea t men t P e r i od ^{. . . . . . . . . . .. . . . . . . . .. . . . . . .. . . . . . . . . . . . • .}45 4 . 2 T r ea t men t P e r i od One ^{. . . .. . . .} . ^{. . . . .} . ^{. . .}. ^{. .} . ^{. . .}. ^{. .. . . . . . . .} . ^{. . .}4 6 4 . 3 Trea tmen t P e r i od Two ^{. . . . .} . ^.. . ^{. . .. .} . ^{.. . . . . . .. . . . . . . . . . . . . . . .} . 48

4 . 4 Pos t -Trea t men t P e riod ^{. . . . . . . .. . . . .} . ^{.. . . . . . . .. . . . . .. . . .} . ^{. . . . .}51 4 . 5 Body We i g h t and Condi tion Score . . . 5 2 4 . 6 Soma t i c Ce l l Coun t ^{. . . . .. . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . .}5 3

4 . 7 P r ed i c t i on o f the F a l l i n Mi lk Produc tion ^{. . . . .. . . . . . . . . .. . . .}5 3 5 DI SCU S S ION ^. . . ^. . ^{. . . .. .} . ^{. .} . ^{. .. . . . . . .}. ^{.. .} . ^. . ^{. . . . ..} . ^. . ^{. . . .. . . . . . . .}6 3 5 . 1 E FFECT OF ONCE DAI LY M I LKING ^.. . ^{. . .} . ^{. .} . ^{. .. . . .. . . . .. . . . . . . . . . .}6 3 5 . 1 . 1 M i lk Produc t i on . . . 6 3 Dura t i on o f t rea t me n t . . . 6 4

Level o f Feed i ng . ^.. . .^. . ^. . . .^{. . . . . . .} . . .^{. . . . . . . . . . . . . . . . . .. .}65 S t age of Lac t a t ion ^{. . .. . . . .. . . . . . .} . ^{. . .}. ^{. . . . . . . .. . . . . . . . . . . .}6 5

5 . 1 . 2 E f fe c t on M i lk Composi tion ^{. ..} . ^{. . . .} . ^{. . . . .. . . . . . . .. . . . . . . . . .}6 7 5 . 1 . 3 E f fe c t on Body Weigh t and Body Condi tion Score . ^{. .} . ^{. . . . . . . .}68 5 . 1 . 4 E f fe c t on Udd e r Heal th . . . 6 9 5 . 1 . 5 E f f e c t o n I n t ramamma ry Pressure . . . 70 5 . 1 . 6 E f f e c t o n Udde r Vo lume . ^{. .. . . .} . . ^. . ^{. . . . . .. . . . . .. . . . . . . . . . . . .}7 1 5 . 2 Pred i c tion o f Fall in M i lk Produc t i on Resul t i ng f rom

Once Da i ly M i lking ^.. .^{. . . . . .. . . . . . . . .}. . ^{. . .. .} . ^{. . .} . .^. . ^. . ^{. . . . . . .}7 2 5 . 2 . 1 R e l i ab i l i t y o f the Fac t o r s Measured . . . 7 4 5 . 2 . 1 . 1 I n t ramammary Pressure ^{. . . .. . . . . . . . .. . . . . . . . . . . .. . . . • .. . . .}74 5 . 2 . 1 . 2 Udd e r Volume ^{. . . . .. . . . . . . .. . . . . . . . . . . . . .. . . .. . . . . . . . • . . . .}75

5 . 2 . 1 . 3 Peak Flow Ra t e ^{. . . . . . . . . .. . . . . .. . . . . .. . . .} . ^{. . . . . . . .. . . . . . .}7 6 5 . 2 . 1 . 4 M i lk Compo s i t i on ^{. . . . ..}.^{. . .}.^{. . . . . . . .. . . . . .} . ^{.. . .}. ^{. . . . .} . ^{. . .}7 6 5 . 2 . 1 . 5 Res i dual M i lk Y i eld ^{. . . . . .. . .. . . . . .. .. . . . . .. . . . . . . . . .. . . .}7 7 6 CONCLUSION . . . 7 9 7 REFERENCES ^{. . . . .. .} . ^{. .. . . . . . . . . .. . . . . . .} .^{. . . . .. . . . .. . . . . . .. . . . . . .}8 1

8 APPENDIX ^{. . . . . . . .. . .. . . . . . . . .. . . . . . . . .. . . . .. . . . . . . . . . . . . .. . . . . .}9 2 Append i x 1 De t e rm i na t i on o f d e c rease i n m i lk p roduc t i on o f

i nd i v i dual cows ^{. .. . . . . . . .. . . . . . . . .. . . . . .. . . . .. . . . . . .}98 Append i x 2 Formula for calcula t i ng Res i dual M i lk Y i e l d ^.. . . ^{. . .} .^. 98 Append ix 3 Ca lcula t ed p e r cen t age Res i dual M i lk Y i e l d ^{. . . . . . . . . .}100

Append i x 4 The mean da i ly IMP at m o r n i ng , noon and a f t e rnoon for cows m i lked once o r t w i c e da i ly . ^{. .. . . . . . . . . . . ..}1 0 3

,

ix

LIST OF TABLES

Page

Table 2 . 1 The y i e lds of m i l k and fa t produced by cows

milked a t equal and unequal in t e rvals ^{. . . . . . . ..} . ^{. . . . . . . .} .^{. .}6

Table 3 . 1 Mean age , day o f lac t a t i on , breed i ng i ndex and m i lk yie ld o f cows as signed t o once o r t wice daily mil king

reg i mes ^{. .. . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . .. . . .}3 3

Table 3 . 2 Summary o f the measuremen t s made dur i ng the t h re e

pe r i od s o f the exp e rime n t ^{. . . . . . .. . . . . . . . . . .. . . .} . ^{. . .. . . .} . . . ^. 3 4

T a b l e 3 . 3 Summary showing the f r equency o f I M P meas ureme n t

dur i ng t h e t h ree p e r i od s o f the t rea t men t . . . 3 7

Table 3.4 Summary showing t h e f requency o f milk y i e ld and

composi tion meas u remen t s d u r i ng the t h ree p e riods of t h e expe r i men t s ^{. . .. .. . . . . . . . .. . . . .} . ^{. . . . . . . . ..} . . ^{. .} . ^{. . .}. ^{. . . . . .} . . ^. 4 0

Table 4 . 1 Leas t square means for var i ous milking t ra i t s for 3 2 cows acco rding t o B I , age , milking f requency and s t age o f lac t a tion during t h e p re - t r e a t me n t p e r i od ^{. . . . . . .. .} . ^. . . ^{. . .} . ^. 54

Table 4 . 2 Leas t square means f o r va r i ou s mi lki ng t ra i t s f o r 3 2 cows accord i ng t o BI , age , mi l k i ng f r equency and s t age o f

l ac t a t i o n d u r i ng t he t rea tmen t p e r i od one . . . 5 5

Table 4 . 3 Leas t square means f o r va r i ous mil king t ra i t s f o r 3 2 cows accord i ng t o BI , age , mi lking f requency and s t age o f

lac t a t i o n d u r i ng t h e t re a t men t p e r i od two . . . 5 6

Table 4 . 4 Leas t square means for va r i ous mi l k i ng t rai t s f o r 3 2 cows according to B I , age, mi lking f r equency and s t age o f

lac t a t i o n d u r i ng t h e pos t - t rea t men t p e r i od . . . 5 7

Tab l e 4 . 5 Body w e i g h t and condi tion s core b e f o r e and a f t e r t rea t men t . 58

Table 5 . 1 Average dec rease i n daily p rod u c t i o n t ra i t s due t o once daily mi lking ove r 3 weeks ( t rea t men t period ) and 7

weeks ( pos t - t re a t men t p e riod ) . . . 6 7

Table 5 . 2 Analys i s o f var i ance o f fac t o r s a f f e c t i ng t h e r e s ponse o f o f cows t o once daily mi lki ng . . . ^. . . . .^. . . . 7 3

x i

LI ST OF FIGURES

2 . 1 R e la t i onship b e t ween udder p ressure and m i lk s e c re t i on

r a t e ^{. . . . . . . .. . . . . . . . . .. . . . . . . .. . . . . .. . . . . . . .. . . . . . . . . . . . .. . .. . .}2 0

4 . 1 The mean weekly m i l k y i e ld for cows mi lked t w i ce da i ly d u r i ng the pre - t rea t men t and pos t - t re a t men t pe r i od and once

o r t w i ce da i ly d u r i ng t rea tmen t p e r i od ^. .^{. . . . . . . . . . . . . . . .. . . . . . .}59

4 . 2 The mean weekly fat y i e l d for cows mi lked t w i c e d a i ly

d u r i ng t he pre- t re a t men t and pos t - t rea t me n t p e r i od and once

o r t w i ce d a i ly d u r i ng the t rea tmen t pe r i od . . . 6 0

4 . 3 The mean weekly pro t e i n y i e ld f o r cows m i lked tw i ce da i ly d u r i ng t h e pre- t re a t men t and pos t - t rea tmen t p e r i od and once

o r t w i ce da i ly dur i ng t h e t rea tmen t pe r i od ^{. .. . . .} . . ^. . . ^{. . . . . . .. . .}6 1

4 . 4 The mean weekly lac t o s e y i e ld for cows m i lked t w i c e d a i ly d u r i ng the p r e - t rea tmen t and pos t - t r ea tme n t p e r i od and once

o r t w i ce d a i ly dur i ng t h e t r e a t men t pe r i od . . . 62

BCS C02 H20 HBI Hg h r IMP kg l LBI mm s . e U . S . A sec

LI ST OF ABBREVIATIONS Body cond i t i o n s core

Carbon D i o x i d e

\.la t e r

H i gh b reed i ng i nd ex Mercury

Hour

In t ramamma ry Pressure k i l og ram

l i t re

Low b reed i ng i ndex M i l l i me t e r

S t andard e r r o r

Uni t ed S t a t e s o f Ame r i ca Soma t i c c e l l coun t