ABSTRACT
Twelve West African Dwarf (WAD) sheep, four in each of parities one, two and three were used to
determine effect of parity and birth type on udder characteristics during pregnancy and lactation, milk
yield and composition and their phenotypic relationships with milk yield . Udder length (UL), udder
width (UW), udder circumference (UC), udder volume (UV), teat length (TL), teat width (TW), teat
circumference (TC), distance between the teat (DBT) and teat height from the ground (THG) of sheep
were measured monthly for the five months of pregnancy and weekly for the twelve weeks of
lactation commencing from four days post partum. Result showed that, parity effect on all udder
characteristics during pregnancy and lactation was highly significant (P < 0.01). During pregnancy
ewes in parity three had highest values (cm) of 8.26, 8.08, 23.95, 1.12, 1.08, 2.49, 287.34, 6.25 and
27.20 for UL, UW, UC, TL, TW, TC, UV, DBT and THG, respectively, followed by ewes in parity
two with values (cm) of 6.30, 7.32, 23.29, 1.05, 0.72, 2.18, 229.3, 5.73 and 23.69 for UL, UW, UC,
TL, TW, TC, UV, DBT and THG, respectively. Those in parity one had least values (cm) of 5.88,
6.33, 22.19, 1.02, 0.69, 2.14, 119.91, 5.35 and 22.02 for UL, UW, UC, TL, TW, TC, UV, DBT and
THG, respectively. During lactation, ewes in the third parity had significantly highest values (cm) of
9.08, 9.00, 39.10, 1.89, 1.24, 3.31, 400.36, 7.11 and 25.98 for UL, UW, UC, TL, TW, TC, UV, DBT
and THG, respectively, followed by those in the second parity with 7.88, 8.66, 35.79, 1.57, 1.03, 2.53,
310.03, 6.56 and 24.95 for UL, UW, UC, TL, TW, TC, UV, DBT and THG, respectively. Ewes in the
first parity had significantly lowest values (cm) of 7.33, 8.35, 32.56, 1.28, 0.93, 2.41, 271.90, 6.28 and
25.98 for UL, UW, UC, TL, TW, TC, UV, DBT and THG, respectively. Birth type effect on udder
characteristics during pregnancy and lactation was highly significant (P < 0.01). Twin bearing ewes
had significantly higher values (cm) of 6.88, 7.31, 23.71, 1.09, 0.85, 2.35, 227.68, 5.86 and 24.68 for
UL, UW, UC, TL, TW, TC, UV, DBT and THG, respectively than those of single bearing ewes (6.74,
7.18, 22.58, 1.03, 0.80, 2.18, 196.64, 5.68 and 23.92 for UL, UW, UC, TL, TW, TC, UV, DBT and
THG, respectively) during pregnancy. During lactation, twin bearing ewes had significantly higher
values (cm) of 8.35, 8.98, 37.25, 1.67, 1.13, 2.82, 364.25, 6.75 and 25.10 for UL, UW, UC, TL, TW,
TC, UV, DBT and THG, respectively than single bearing ewes with values of 7.84, 8.36, 34.38, 1.49,
1.01, 2.69, 290.61, 6.55 and 24.65 for UL, UW, UC, TL, TW, TC, UV, DBT and THG, respectively.
Ewes in the third parity had highest mean milk yield of 228.95 ml followed by ewes in second parity
(157.18 ml), while ewes in the first parity had least milk yield of 126.42 ml. Twin bearing ewes in the
third parity had highest mean milk yield of 249.09±14.85 ml during lactation. Single bearing ewes in
the first parity had the smallest mean value of 124.54 ml. Parity effect on milk composition was
highly significant (P < 0.01) for moisture, total solid, solid not fat, protein, fat and ash but not
significant (P > 0.05) for lactose. Ewes in the third parity had highest mean values (%) of 79.24,
20.73, 12.98, 6.58, 7.84, 0.77 and 5.53 for moisture, total solid, solid not fat, protein, fat, ash and
lactose, respectively, followed by ewes in the second parity with 80.95, 18.84, 11.79, 6.04, 6.27, 0.76
and 4.98 for same constituents while ewes in the first parity had the corresponding values of 82.75,
17.25, 10.63, 5.48, 6.61, 2.75 and 3.37. Birth type effect on milk composition was highly significant
(P < 0.01) for all milk constituents except total solid and lactose. Twin bearing ewes had significantly
higher mean values (%) of 80.86, 18.94, 11.85, 6.06, 7.29, 0.768 and 4.97 for moisture, total solid,
solid not fat, protein, fat, ash and lactose respectively, than those of single bearing ewes with 81.08 %,
18.92 %, 11.75 %, 6.00 %, 7.18 %, 0.760 % and 4.96 % for corresponding constituents. The
correlation coefficients between udder dimensions and milk yield were; 0.92, 0.79, 0.91, 0.92, 0.86,
0.88, 0.60, 0.08 and -0.24 for UL, UW, UC, TL, TW, TC, UV, DBT, and THG respectively.
TABLE OF CONTENTS
Content Page
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgement v
Abstract vi
Table of content vii
List of tables ix
List of figure xii
CHAPTER ONE
1.0 INTRODUCTION 1
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 The distribution and potential of sheep in the tropics 4
2.2 Advantages of West African Dwarf (WAD) sheep 5
2.3 Reproductive potentials of WAD sheep 6
2.4. Milk yield potentials of diary ewes 6
2.5 Nutrient requirement of pregnant and lactating ewes 9
2.6 Mammary gland development in ewes 12
2.7 Udder measurements and their importance 14
2.8 Lactation persistency 15
2.9 Unique nutritional values of sheep milk 17
viii
2.10 Composition of sheep milk 17
2.11 Factors affect milk yield and composition of sheep 24
2.12 Animal factors 26
2.13 Environment 31
2.14 Management practices 33
2.15 The use of sheep milk 35
2.16 Conservation of fresh milk 37
2.17 Management of diary sheep 38
CHAPTER THREE
3.0 MATERIALS AND METHODS 39
3.1 Experimental site 39
3.2 Experimental animals 39
3.3 Experimental design 39
3.4 Management of experimental animals 40
3.5 Data collection 42
3.6 Statistical analysis 44
CHAPTER FOUR
4.0 RESULTS 45
CHAPTER FIVE
5.0 DISCUSSION 72
5.1 Conclusion 77
5.2 Recommendation 79
REFERENCES 80
CHAPTER ONE
1.0 INTRODUCTION
The shortage of animal protein is a common problem facing many tropical countries
including Nigeria (FAO, 2003). It was reported by Akinfala et al. (2003), that the supply of
animal protein for human consumption in Nigeria was below the demand. Despite the
numerous advantages associated with the consumption of animal protein, the minimum intake
recommended by FAO (1992) has not been met in most developing countries. Harold (1984)
reported that meat was assumed to be the only product from cow when it was domesticated,
whereas other dietary products from cattle included milk and its products. Harold (1984)
further reported that animal milk was first known to have been used as human food around
5000 B.C. and it was first used as human food in the Middle East.
Meanwhile, the Food and Agricultural Organisation (FAO, 2001) reported that the world
milk production percentage from cow was 84.6 % while that of sheep was 1.3 %. The
composition of different kinds of milk as reported by George (2001) shows that the
nutritional value of sheep milk with 19.30 % solids, 7 % fat, 5.98 % protein, 193 mg calcium,
and 108 kcal is superior in quality to those of cow and goat with 12.01 % and12.97 % solids,
3.34 % and 4.14 % fat, 3.29 % and 3.56 % protein, 119 mg and 134 mg calcium and 69 kcal,
respectively. There is therefore need to increase milk production from the sheep.
Adewumi and Olorunsomo (2009) pointed out that increasing demand for milk and its
products in Nigeria has made it imperative to look for other sources of milk apart from cattle.
According to the authors, local milk production has consistently fallen short of demand over
the years, especially in urban centres leading to massive importation of milk and milk
products. Continuous dependence on imported milk has led to increase in cost of milk
2
thereby pushing these products beyond the reach of the average Nigerian. Hence, it is
necessary to look for alternative sources of milk for local consumption.
Local sheep breeds in Nigeria have potentials to supply a significant portion of the milk
deficit in the country because sheep numbers far exceed cattle numbers in both rural and
urban communities (Rim, 1992; Adewumi, 2005). They are also more affordable to resourcepoor
families and produce more milk in relation to body size than cattle (Nuru, 1985).
Sheep milk has been found to be richer in critical nutrients except lactose, than the milk of
humans, cattle and goats (Buffano et al, 1996). The high content of vitamin D and calcium in
sheep milk helps in fighting against osteoporosis. It is very useful in the treatment of neurotic
indigestion, insomnia, dyspepsia, peptic ulcer, pyloric stenosis and rheumatism. It is also
perceived by some consumers in Nigeria to have a better and more natural taste than cow
milk (Adewumi et al., 2001). Sheep milk contains a higher proportion of short and medium
chains fatty acids and more conjugated linoleic acid (CLA) which is a cancer fighting and fat
reducing compound (George, 2010). It produces a higher cheese yield of cheese per litre than
that of cow or goat milk (Assenat 1985, Chamberlain 1989, and Adewumi et al., 2001).
The higher casein content makes the rennet coagulation time for sheep milk shorter and the
curd firmer (Jandal, 1996). It has also been proposed as a more natural and better tasting
alternative with great nutritional and clinical potential (Hardy, 2000). In spite of this
potential, sheep have largely been neglected by researchers in the quest for increased
production (George, 2001).
Apart from dry season feeding which was reported to be a major constraint confronting
ruminant production in Nigeria (Bawala et al., 2007; Ademosun, 1994), Chukuka et al,
(2010) reported that low genetic potential is also a prominent constraint to ruminant
3
production. According to the authors most indigenous breeds of small ruminants in the
tropics have not been selected for high productivity. The low genetic potential of WAD sheep
and goats is often quoted as a major constraint to meat and milk production in Sub-Saharan
Africa, hence the need for animal improvement programmes.
It is therefore imperative to research into indigenous sheep breed (WAD) with the aim of
discovering its milk yield potentials and quality.
1.1 STUDY OBJECTIVES
The objectives of the study were as follows;
(i) To determine the milk yield of WAD Sheep in the humid tropical zone of Nsukka.
(ii) To evaluate the composition of the milk.
(iii) To evaluate changes in udder characteristics of WAD Sheep during gestation and
lactation.
(iv) To establish relationships between udder characteristics and milk yield during
lactation.
1.2 JUSTIFICATION
Sheep milk is one of the protein sources which has found a niche in human nutrition. Apart
from being highly nutritious, sheep milk sells for a significantly higher price/kg, almost four
times the price of cow milk. (George 2010). Most of the sheep milk produced in the world is
made into cheese. It is also processed into yoghurt and ice cream and the United States of
America is a large importer of sheep milk cheese. (George 2010).
Therefore, it is very important to carry out this research in order to discover the milk
production potentials of an indigenous breed (West African Dwarf) of sheep.
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