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 CONTENT
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
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
LIST
OF TABLES
Table Page
- Recommended nutrient intake and dietary nutrient content for a mature 70 kg ewe at various physiological states 10
- Composition of supplemental diet 41
- Proximate composition (g/100gDM) of supplemental diet fed WAD sheep 46
- Least square means (cm) showing the effects of birth type and parity on udder characteristics of WAD sheep during pregnancy 47
- Least square means (cm) showing the effects of month of pregnancy on udder characteristics of WAD sheep during pregnancy 49
- Least square means (cm) showing the effects of interaction between parity and birth type on udder characteristics of WAD sheep during pregnancy (UL, UW and UC) 50
- Least square means (cm) showing the effects of interaction between parity and birth type on udder characteristics of WAD sheep during pregnancy (TL, TW and TC) 51
- Least square means (cm) showing the effects of interaction between parity and birth type on udder characteristics of WAD sheep during pregnancy (UV, DBT and THG) 52
- Least square means (cm) showing the effects birth type and parityon udder characteristics of WAD sheep during lactation 55
- Least square means (cm) showing the effects of week of lactation on udder characteristics of WAD sheep during lactation 56
- Least square means (cm) showing the effect of interaction between parity and birth type on udder characteristics of WAD sheep during lactation (UL, UW and UC) 57
- Least square means (cm) showing the effect of interaction between parity and birth type on udder characteristics of WAD sheep during lactation (TL, TW and TC) 58
13. Least square means (cm) showing the effect of interaction between parity and birth type on udder characteristics of WAD sheep during lactation (UV, DBT and THG) 59
14. Least square means (%) showing the effect of birth type and parity on milk composition of WAD Sheep. 60
15. Least square means (%) showing the effect of week of lactation on milk composition of WAD Sheep 62
16. Least square means (%) showing the effect of interaction between parity and birth type on milk composition of WAD Sheep 63
- Least square means (%) showing the effect of interaction between parity and birth type on milk composition of WAD Sheep 64
- Least square means (%) showing the effect of interaction between parity and birth type on milk composition of WAD Sheep 65
- Least square means (ml) showing the effect of birth type and parity on milk yield of WAD Sheep 67
- Least square means (ml) showing the effect of week of lactation on milk yield of WAD Sheep 68
- Least square means (ml) showing the effect of interaction between parity and birth type on milk yield 69
- Phenotypic
correlation between udder characteristics and milk yield of 71
WAD sheep
LIST OF FIGURE
Figure Page
1.
Diagram showing factors affecting milk yield and composition 25
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 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 resource-poor 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
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
EFFECT OF PARITY AND BIRTH TYPE ON UDDER CHARACTERISTICS, MILK YIELD AND COMPOSITION OF WEST AFRICAN DWARF SHEEP
