Response of cow's milk composition to changes in environmental temperature : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University

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Copyright is owned by the Author of the thesis. Permission is given for

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RESPONSE OF COWS MILK COMPOSITION TO CHANGES IN ENVIRONMENTAL TEMPERATURE

A thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science

at Massey University Palmerston North

DENNISTER DI~S B~NDhRANAY~KA

1971

I

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1 • 1 1 • 2

( a) (b)

( C)

( d) ( e) ( f) ( g) 1.3 1. 4

(a)

CH:,PTER TWO

2.1

2.2 2.3

(a) (b)

2.4

2.5 2.6

(a)

TABLE OF CONTENTS

CHJ~PTER ONE

Introduction

Thermoregulatory Responses of Cattle to Thermal Stress

Cardiovascular Responses

Respiratory Rate and Respiratory Evaporative Heat Loss

Sweating Rate and Cutaneous Evaporative Heat Loss

Food Intake and Digestion Water Consumption

Engergy Metabolism Endocrine Responses Rumen Characteristics Productive Responses

Milk Yield and Composition

M .. TERL.,LS ,,ND METHODS

f,nimals

Housing and Management Feeding

Feed

Feeding During the Experimental Period Measurement of Respiratory Rate and Rectal Temperature

Milking

Sampling and Tests Milk Composition

Page No.

2

4

6 7

8

10 12 15 17

19 19

26

27

28

29 29 31

33

34

35 35

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( C) Osmolarity

( d) Fatty :,cid Composition of Milk Fat

2.7

Sampling Rumen Liquor and Tests (a) pH

(b) Concentration of Volatile Fatty ,·,cids (c) Proportions of Volatile Fatty :.cids

2.8

Statistical i,nalysis of Data

CH,,PTER THREE RESULTS

3. 11 3.12 3. 13 3 ⁰14

3 .17 3. 18

3.20 3.21

Respiratory Rate Rectal Temperature Food Intake

Vater Consumption Rumen Characteristics Milk Yield

Fat Percentages , Yield of Fat and Molar Percentages of Milk Fatty ~cids Protein Percentages and Yield

Lactose Percentages and Yield Osmolarity

Cell Content of Milk Body Weight Changes

CH~PTER FOUR DISCUSSION

4.1 Thermoregulatory Responses 4.11 Rumen Characteristics

4.12 Milk Yield

4. 13 Milk Composition

Page No.

38

41

42

43

44

45

46

48

55 57

62

65 67

68

69

70

71

74

77

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Page No.

( a) Fat

78

(b) Protein

82

( C) Lactose

84

( d ) Osmolarity

85

(e) Cell Content

86

Summary

87

Conclusions

88

Bibliography

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Table

1 1 • 11 1. 12 1. 13 1. 14

1.15 1. 16

1. 17

1.

18

1. 19

1.20

1. 21

1. 22 1.23

1.24

1. 25 1.26

1.27 1. 28

L1ST OF' T:,BtES

Respiratory Rates

Daily Rectal Temperatures Intake of Dry Matter Lb. Daily ~ater Consumption Lb.

Daily ~ater Consumption Lb.

Pr eliminary-Experimental Period Means Rumen pH

Changes in Rumen pH Preliminary-Experimental Period Means

Mol ar Proportions of Vol atile Fatty ,.cids of Rumen Liquor

Changes in Molar Proportions of Volatile Fatty ~cids of Rumen Liquor

Preliminary-Experimental Period Means

Mol ar Concentrations of Volatile Fatty ~cids of Rumen Liquor

Changes in the Molar Concentration of Volatile Fatty ~cids of Rumen Liquor

Preliminary-Experimental Period Means Daily Milk Yi eld

Daily Fat Corrected Milk Yield Decline in the Daily Milk Yield

Decline in the Daily Fat Corrected Milk Yield Lb Preliminary-Experimental Period Means

Fat Percentage

Change in the Fat Percentage Preliminary- Experimental Period Means

Daily Fat Yield Lb.

Decline in Daily Fat Yield Lb.

Page No.

43

44

45

46

47 48

50

51

52

53 54 55 56 57

58

59

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1. 29

1. 30

1. 32

1.33 1 . 34 1 . 35 1 . 36 1 . 37 1 . 38 1 , 39

1.

40

1. 41 1042

Molar Percentages of Milk Fatty ~cids Changes in the Molar Percentages of Milk Fatty hcids. Preliminary-Experimental Period Means

Protein Percentage Fat Free Serum

Decline in Protein Percentage F~t Free Serum. Preliminary-Experimental Period Means

Daily Protein Yield Lb.

Declines in Daily Protein Yield Lb. Preliminary-Experimental Period Means Lactose Percentage Fat Free Serum Daily Yield of Lactose Lb.

Decline in Lactose Percentage Fat Free Serum Preliminary-Experimental Period Means

Decline i n Daily Lactose Yield Lb. Preliminary-Experimental Period Means

Osmolarity of Daily ~.M. and P.M. Milk Samples. Miliosmoles/Lit.

Decline in Osmolarity of Daily Milk Samples. Preliminary-Experimental Period Means

Cell Content of Milk In CM. Body Weight Changes Lb.

Page No.

60

61

62 63

63 64

65

66

67

68

69

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Appendix I

Appendix II

Appendix IlI

Appendix IV

Appendix V

Appendix VI

Appendix VII

Appendix VIII

Appendix IX

Appendix X

,,ppendix XI

/,ppendix XII

i,ppendix XIII

1\ppendix XIV

APPENDICES

Daily Water Consumption - Analysis of Variance

Rumen pH Zero Hours Post Feeding - Analysis of Variance

Acetic tcid Nilimoles

% -

Analysis of Variance

Propionic Acid !iilimoles

% -

Analysis of Variance

Butyric Acid Milimoles

% -

Anal ysis of Variance

A.M. Fat Percentage - Analysis of Variance

P.G. Fat Percentage - Analysis of Variance

Daily Fat Yield - Analysis of Variance

Molar ~e~centa~es cf_c

6 -

c

₁₄^M^ilk

Fatty ,~cids - ,,nalysis of Variance Molar Percentages of c,B:O +

c, 8 :1 +

c,8:Z +

c,

₈^:₃ ^- Analysis of Variance

Molar Percentage of C

8 Milk Fatty Acid

.. 1

- lnalysis of Variance

l .M. Protein Percentage - ~nalysis of Variance

P.M. Protein Percentage - l nalysis of Variance

Osmolarity of Milk Miliosmoles/Lit -

~nalysis of Variance

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ACJrnOWLEDGEMENTS

It is indeed a pleasure to thank Professors I.L. Cmpbell Dean of the Faculty of hgriculture and Horticulture, D.S. Flux Head of the Department of Dairy Hysbandry and R.E. Munford for their invaluable help and advice. I am deeply indebted to my Supervisor Dr C.W. Holmes of the Department of Dairy Husbandry for his continual interest

invaluable help and guidance. I wish to thank Mr A.D.F. Davey for permission to use his unpublished data, Mr 0.B. Currie and

Mr ~.½.F. Davey also of the Department of Dairy Husbandry for their advice and help.

For the grant offered by the New Zealand Government through the Colombo Plan for Technical Co-operation in South and South East ~sia I am v~ry grateful.

I also wish to thank Syliva, Graham Juke, the staff of the

lnimal Physiology Unit, Miss Campbell and the staff of Massey University Library for their valuable assistance.

To Elaine Ross for the typing of the script at such short notice I am very thankful.