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A COMPARATIVE sr.t.JDY"

OF THE � OF TWO ST.OCKJNG LEVELS ON

WOOL FOLLICLE DEVEI.OIMENT AND WOOL :mODUariON

OF THE NEW ZEALAND

ROMNEY

SHEEP

A thesis

presented in partial fulfilment of the requirement for the Degree

o£

Master

of Agrioul tural Science

in Ammal

Science

at

Massey Universit;y

R. M. W.

SUMNER

Jaruary lL969

The author is indebted to Dr. G.A. Wickham for assistance and encouragement during the carrying out _of

this

trial _and to _Dr. F.R.M.

Cockrem

for

both

statistical advice and the writing of _the statistical eompu ter progr_amnes.

'llhanks are extended to G. Black, Miss _K. Nikolaison, Miss L.

Sigley and B. Thatcher for technical assistance; to M. Divehall,

R .

Fairhall. and P. Whitehead for co-operation _in the management of the animals; and to the library staff for locating reference material.

The work was carried out while the author held a Wool Bursary from the New Zealand Department of Agriculture .

INl'ROIUOI'ION.

1

REVIE.W OF LITmATURE.

TABLE OF CONTENTS.

A. WOOL

FOLLICLE DEv.EIDBvlENT.

Page

�

3

1. The Developmental Pattern of the Wool Follicle.

3 2.

The Developmental Pattern of the Follicle Gra.tp.

5

3. The Influence of Nutrition on Follicle Develop-

me�.

9

B. SEASONAL WOOL GROWTH.

1 . Historical - Pre �949.

2. Seasonal Wool Gro.vth Studies under Grazing Con-

ditions.

15

3. Seasonal Wool Gr<:M--th Studies under Conditions

of Controlled Feeding.

18

4.

The Control of the Seasonal Rhythm of Wool Grc.vth.

5.

The Seasonal Rhythm of Associated Glands.

C. WOOL ffiOWOTION AND FLEECE OHA.RAO'rmiSTICS.

1 .

':nhe Effect o f Increased Stocking Levels o n Wool Froduction

and

F leece Characteristics .

2.

Blenotypic Inter-relationships between Varirus

21 22

Fleece Characteristics.

27

2

DESORIP.ri0N OF THE ^GRAZING UNI'DS AND THEm. MANAGE-

MENr .

29

3 THE

_EFFEC'll' OF 'I!!NO DIFF'l!Rimr GRAZING ENVm.ONMENTS ON FOLLICLE DEVEIDPMENT .

A. lNTROIXJOI'ION.

33

B:. MA.'DERIALS AND M&rHODS.

1.

Selection of Animals.

2. Sampling.

3. Histological Technicpes.

4. Me^as.1renent of _the Follicle Population.

5 .

Statistical Technicpes.

O. ^RESULTS.

1. 1966

Lambs.

2.

₁₉₆₇ lambs.

D. DISCUSSION.

4 THE EFFE01' OF TWO DIFFERENT GRAZlNG ENVIRONMENTS ON THE SEASONAL PATTERN ^OF WOOL GRovmi.

A. INTRODUCTION.

B • MATERIALS AND l.ffi'TIIODS.

1. Selection of An.irm.ls.

2. Samp^ling.

3. Soruring.

4. Fibre Length Esti!xa tion.

5 .

Fibre Diameter Estimation.

G:. Statistical Technicpes.

0. RESlJilrS.

1. Ewe Hogget Data.

2 .

Adult Ewe ^Data.

D. DISOUSSION.

5

THE EFFECT.' OF TWO DIFFmmNT

GRAZING

ENVIRONMENTS ON WOOL IROIXJOTION .AND FLEECE CHARAa.rmiSTIOS.

A. INTRO:OOOTION.

35 36 38 38 39

4l 53 61

66 67 67

68 68 6S

82 102

106

E. MA.'11ERIAIS AND ^ME.rHODS.

1. Ewe Hogget Fleece Sampling.

2. ^Shearing.

3. Pre-Scooring Fleece Characteristic Grading.

4. Soooring.

5. Post-Scouring Fleece Characteristic Grading.

6. Fibre Diameter Estimation.

7. Statistical Teclmiquea.

C. RESULTS.

1. Ewe Hogget Data.

2. Adult :E.We Data.

D. DISCUSSION.

6 SUMMARY AND CONCIJJSIONS.

B[BLIOGRAFHY.

APPENDICES.

I. A Comparison of Square and Circular Sampling Areas

108

108

109

110 110 llO' 110

111 113 122 128

130

in the Estimation of Follicle Population Densities. 135 II. The Recalibration of an Airflow Apparatus Following

a Reduction of the Size of the Chani>er.

III. Descriptions of the Fleece Characteristic Grading System.

Figure 1.1

1.2 2.1

4.1

II.l

LIS£ OF FIGURES.

Stages of developn:ent of

(

a..

)

^primary wool follicles and (b) original secondary wool follicles.

A follicle group.

(a) Monthly rainfall _a.nd (b) mean monthly temperature.

New born lamb following the taking of a. skin section.

Photomicrograph of skin section at birth of an Intensive twin anime� born to a 2 year old dam.

Seasonal variation in body weight.

(b) Adult ewes. (a) Ewe hoggets.

Seasonal variation in wool weight _{per unit}

area.

(a) Ewe hoggets. (b) Adult ewes.

Seasonal variation in

(a) adult

evte fibre length a.nd {b) adult ewe fibre diameter.

The rethod of adapting an airflow apparatus to es

t

i

­

mate the average fibre diameter of a lg wool sample.

II.2 The relation between the 2g diameter and the lg diameter.

Page

4 6 3�

37 59 71 Tl 91

Table 1.1

2.1

3.A

3.B

3.10

4.. 1

LISr OF

TABLES.

The relation between

the

physical enviroiiiOOnt

and the

output of associated

_glands.

P.henot.ypic COlTelations between fleece characteristics.

auw

er of stook grazed on the experirental units as at March of each yea:r.

1966

Lanibs; Skin saJr!Ple groops.

1967 Lambs; Skin

sample

_grrups.

Date and

^mean

age of ani.mal.s at each SaiJ!>ling.

1966 Lambs; Grcup reans

for body weight.

1966

Lanibs;

Mean SCJ!.lares for body weight.

1966 Lambs; Grcup

means for primary follicle density.

19G6

Lambs;

Mean

scpares for prirre.ry

follicle

density.

1966 La.Iribs;

Grru.p means

for secondary follicle density.

1966 Lambs; Mean Sq).l.ares for secondary follicle density.

19G6

Lambs; Grcup reans for P:f Sf ratio.

1966

lalribs;

Mean scpare

s for � ratio.

1967

La.ni:ls;

Body we

i gh t. (a) Grcup means.

(b) Mean scpares.

19�7 Lambs; Primary

follicle density. {a)

Gralp

reans.

(b) Mean

squares.

1967

lembs; Secondary follicle density. (a) Group means. (b) Mean squares.

1967

lembs; � ratio. (a) Grcup means. (b)

Mean scpare s .

Ewe hogget monthly sa.Dple grwps.

Adult ewe monthl.y saJI!Ple grwps.

Sampling dates.

Page

23 28

30 35 36 42

4

3

44 45 47 48

49 51 52

54.

55 57

4.2 Ewe hogget; Mean squares for body weight.

72

4.3 Ewe hogget; Mean squares from within group regression

analysⁱs of body weight. 74

4.4 Ewe hogget; Mean squares from an ana.lysis of covar-

iance of body weight. 75

4.5 Ewe hogget; Adjusted body wei^{ght 100ans.} 76 4.6 Ewe hogget; Mean squares from within group regression

analysis of clean wool weight. 79

4.7 :B.r'we hogget; Mean squares ^from an analysis of covar-

i.ance of clean wool weight. ₈₀

4

_.8 Ewe hogget; Adjusted clean wool weight 100ans . 81 4.9 ^Adult ewe; Mean squares for body weight. 83 4.10 Adult ewe; Mean scpares from within grrup regression

a.na.lysis of body weight. 84

4.ll

Adult ewe; Mean squares ^{from an} analysis of covariance

of body weight. 85

4.12

Adult ewe; Adjusted body weight reans. 86 4.13 Adult ewe; Mean squares from within grrup regres^si^on

analysis of clean wool wei^ght

.

88

4.14 Adult ewe; Mean squares from an ana.lysis of covariance

of clean wool weight. 89

4.15 Adult ewe; Adjusted clean wool weight reans. 90 4.16 Adult ewe; Mean squares for fibre length. 9

2 4.17

.A.dul t ewe; Mean squares from within grrup regressi^on

analysis of fibre length. 94

4.18 ^· Adu.l t ewe;

Mean

squares from an analy^sis of covarianoe

of fibre length. 95

4.19 Adult ewe; Adjusted fibre length means. 96

4.20

Adult ewe; Mean squares for fibre d�ter. 97

4.21

^{Adult ewe;} Mean s<pares from within group regression

a.na:cysis of fibre diameter.

99

4.22

Adult ewe;

Mean

squares from

an

anaJ.3rsis of covarial'¥)e

of fibre diameter. lOO

I.l

I.2

Adult ewe; Adjusted fibre diameter means.

Fleece characteristic group means.

Fleece characteristic mean s�ares.

Ewe hoggets; Correlations between the fleece charact­

eristics.

Adult ewes; Correlations between the fleece charact­

eristics.

Follicle pop1le.tion means obtained by the "Scpare"

and "Circle" methods.

Mean scpares for foll icle population neans obtained by the "Scpare" and "Circle" methods.

101 112

ll6 118 137