EFFECT OF PARITY AND BIRTH TYPE ON UDDER CHARACTERISTICS, MILK YIELD AND COMPOSITION OF WEST AFRICAN DWARF SHEEP

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

1. 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

1. Least square means (cm) showing the effects of week of lactation on udder characteristics of WAD sheep during lactation                      56
2. 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
3. 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                

1. Least square means (%) showing the effect of interaction between parity and birth type on milk composition of WAD Sheep      64   
2. Least square means (%) showing the effect of interaction between parity and birth type on milk composition of WAD Sheep                  65
3. 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

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