A study of milk production as it affects lamb growth in Romney and Cheviot crossbred sheep : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science of the University of New Zealand

Copyright is owned by the Author of the thesis. Pennission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the pennission of the Author.

MASSEY AGRICULTUPAt. t:Q!,b1§[

LIBRARY PALMERSTON H~t{fH1 ,-,b

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:Definition of Terms used

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Matex-:tale ancl stock

- - - -

1

!!!,_1'\..l! -

M1 lk Yield

39

.§_!tcti2.,9...l - Bre(:d

.r,.:,

section I I - The n;ttect of Pre•-and Poat-

- - - - Partum Level of Nutri t1on

5ft.

!!!tCtion fil -

Tile number

of

Lambs

per

Ewe

56

Section IV - Age

56

§..f!!_,Y,on

:y_ -

Liveweigb.t

5i'

S e c t i ~ . - Climate

59

Section VII• The Time of Lambing

59

section

]1..ll,""".F;we

Health 59

Section ·Ix - The Relationship Between :Ewe - Milk Index and the Birth

,Vf e1ght of Lambs

tO

Part III - Milk Oompoai tion

61

- -

(1) Breed

66

(2) Stage

Qf

Lactation 70

( :,) L,nel of

Nutrition 70

( If.} Climate

71

( 5) Age

71

Ind1"1.0U&l :Milk Constituents

- - - -

( A) Total Solids

(B) Solide-Not-Fat

( C) Fat

71

72

72

--

(11)

7.

(E) · Lactose 75

(F) Ash

7'

(G) CalCJ.u

(B) Phospbol"tls

71

(1) Birth

{2)

(3) Milk Y1

( IJ,) Lamb Growth

Carat

Romne:v

s

ilk

ttrr-11

Summary

tract

clnsio

Ai;>P

1

80

-,

9

0

10 107

117 12:

1

125

- 5 -

agencies, determines largely how close the hereditary potentia.l fc>r growth will be approached.

Hammond ( 1+) postulates that nutr1 tional conditions in early life limiting growth can materiHlly af'feet the ultimate development of the animal,

Brody ( 5) attempts to analyse the effect ot productive improvement a a

it

approaches the h.eredi tary potential of the animal for either growth, nruscular work

or milk production. As product! vi ty, due to incx•eased growth rate or JDilk production 1a improved, the question of e:ff'icien~y both in physiological and economic terms becomes important.

Efficiency is not a simple concept ... it mus·t be viewed from

the several

points ot -

( 1) That pex•ta1ning to the animal (2) That of the farmer

( 3) That of immediate e:fficienc1, and

( 4) That of long range efficiency.

Whether increased. producitivity results in greater immediate efficiency depe:nds on the relative acceleration of the productive process on one hand, and the maintenance coat on the other. But granted an increase in iDDnediate efficiency, how will this affect the long range efficiency, viz: health, :t'ertility and longevity? Also while energetic

etreoiency,

the ratio of the desired form of' output energy to the given f'orm of input energy (Brody (6) ) is of importance to the farmer, monetary profit has an over-riding value.

That conversion of feet! to animal products wl th equal energetic efficiency may not retum equal profit, is explained by the fact that fixed costs per animal are leas in

-

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