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INFLUENCE OF NUTRITION AND BODY CONDITION AT FIRST MATING ON THE REPRODUCTIVE PERFORMANCE OF GILTS IN THE HUMID TROPICS

Animal Science Project Topics & Materials

ABSTRACT

 

Two experiments were conducted at the piggery unit of the Department of Animal Science Farm, University of Nigeria, Nsukka, from July 2007 to March 2009, to determine the effect of nutrition and body condition at first mating on the reproductive performance of gilts. The first experiment evaluated the effects of feeding different combinations of protein and energy diets on age at onset of first observed oestrus, growth rate, backfat reserve and body condition score of the gilts from weaning to puberty. Fifty-four (54), eight week old weaner gilts were used for this trial. They were randomly assigned to nine experimental treatment diets having different combinations of protein (16%, 18% and 20% crude protein) and energy (2800 kcal/kg, 3000kcal/kg and 3200kcal/kg) with six (6) gilts per treatment. The gilts in each treatment were housed in pairs making up three (3) replicates per treatment. Estrus detection was carried out twice daily at 0800hr and 1600hrs in the presence of mature boar beginning from the age of five months. Blood samples were collected from two pigs per treatment by humane puncture of the ear vein for haematological and biochemical analysis. In addition, two (2) gilts from each treatment were randomly selected, slaughtered and their reproductive organs excised and examined. Linear body measurements (body length, chest girth, height at withers and flank-to-flank) were also recorded. Data collected were analyzed according to factorial arrangement of treatments in a completely randomized design (CRD) whereas stepwise multiple linear regression analysis was used to generate prediction equations between body weight and linear body measurements. In experiment 2, eighteen (18) gilts with different body conditions and backfat thickness were selected and assigned to experimental treatments with six gilts per treatment. All the gilts were weighed and mated twice at the second observed estrus. Pregnancy was confirmed by the gilt not returning to heat after 21 days of observation for signs of heat after breeding. Gilts were fed 2.1 kg of an 18% CP diet daily throughout gestation. Their feed was increased to 3.0 kg of feed daily during lactation until weaning. Gilts were monitored and their reproductive indices recorded throughout gestation and lactation. The pre-weaning performances of their piglets were also recorded until weaning at day 35. Data collected were subjected to one way analysis of variance (ANOVA) for a completely randomized design (CRD). Results of the first experiment indicated that diet containing 3000kcal/kg or 3200kcal/kg metabolizable energy and 18% crude protein was the optimum required for gilts to grow faster and reach the minimum threshold of age, body weight, backfat reserve and body condition necessary for early attainment of first oestrus and future reproductive processes. On the other hand, the result also showed that when pork of a moderate fatness (lean pork) is in demand, gilts should be fed diets having 2800kcal/kg of metabolisable energy and either 16 or 18% crude protein. High coefficient of determination (R2) values of 0.96, 0.95, 0.93 and 0.45, respectively, were recorded between body (Y) weight and body length (BL), heart girth (HG), flank-to-flank (FF) and height-at-withers (HW) measurements. Prediction equations for body weight of the gilts were, Y = 0.83 x BL – 33.53, Y = 1.07 x HG – 37.86, Y = 1.22 x FF – 37.14 and Y = 0.86 x HW – 14.83. Results of the multiple linear regression showed that with effective management, farmers, researchers and prospective pig buyers can use the prediction equations for body length, heart girth and flank-to-flank measurements to easily estimate the body weight of their pigs especially, during selection, drug administration and/or determination of market weight and prices. In the second experiment, results showed that body condition of gilts at mating affected their gestation weight gain, lactation body weight losses, litter size at birth and weaning, growth rate of their piglets, pre-weaning mortality and weaning-to-estrus intervals, etc in favour of gilts with normal and fat body conditions. It was concluded that in any commercial pig industry where the management is interested in increasing sow lifetime productivity, replacement gilts should be scored for body condition both subjectively and objectively using ultrasonic equipment to determine their readiness to undergo the stress of growth and reproduction. From an economic point of view, this is an important factor that should be considered to determine the total value of pigs produced within a given cycle. Hence, it is recommended that breeding gilts should have at least between 15mm and 18mm backfat thickness at first mating for effective and more balanced reproductive processes.

 

TABLE OF CONTENTS

Pages

Title Page………………………………………………………………………………………….i

Certification………………………………………………………………………………………ii

Dedication………………………………………………………………………………………..iii

Acknowledgement………………………………………………………………………………..iv

Abstract…………………………………………………………………………………………..vi

Table of Contents………………………………………………………………………………..viii

List of Tables………………………………………………………………………………….…xiv

List of Figures……………………………………………………………………………………xvi

CHAPTER ONE      1

1.1  INTRODUCTION      1

1.2  OBJECTIVES OF THE STUDY        4

1.3  JUSTIFICATION       4

CHAPTER TWO     7

LITERATURE REVIEW   7

2.1    GROWTH OF PIGS  7

2.1.1                Measures of postnatal growth in pigs 7

2.1.2        Allometric growth           8

2.1.3                Nutritional influence on growth rate  8

2.1.4                Effect of temperature on growth of pigs        9

2.1.4.1            Effect of temperature on performance of pigs           10

2.1.4.2            Effect of temperature of growth rate of piglets         11

2.1.5                Physiological effect of hormones on growth  12

2.1.6                Birth weight in relation to postnatal growth of pigs   14

2.1.7                Prenatal development of muscle fibre in the pig        15

2.1.8        Growth rate of pigs relative to their birth and weaning weights……………………….15

2.2    NUTRIENT REQUIREMENTS OF PIG     16

2.2.1                Protein and amino acids requirements for growth of pigs      17

2.2.2                Energy intake of gilts and sows          18

2.2.2.1            Physiological explanation for small litter size, reduced conception rate and follicular growth          18

2.3    NUTRITION AND REPRODUCTIVE PERFORMANCE            19

2.3.1                Nutrition and ovulation rate   19

2.3.2                Nutrition and puberty 21

2.3.3                Energy restriction and length of estrus cycle  21

2.3.4                Influence of diet on follicular development   22

2.3.5                Influence of diet on embryo survival  22

2.3.6                Feed intake and weaning-to-oestrus interval  23

2.4    PHYSIOLOGICAL PATHWAY INVOLVING NUTRITION AND REPRODUCTION           24

2.4.1                Physiological role of insulin on reproduction 24

2.4.2                Nutrition and hormonal mechanisms involved in reproduction.         25

2.4.3                Physiological relationship between high feed intake and progesterone secretion      25

2.5    MANAGEMENT AND FEEDING OF GILTS DURING GESTATION  26

2.5.1                Gestational weight gain          29

2.6    FEEDING OF GILTS DURING LACTATION      30

2.6.1      Effect of lactation feed intake on weaning-to-estrus interval      31

2.6.2      Effect of lactation feed intake on ovulation rate…………….………………………….31

2.6.3      Lactation body weight loss           31

2.7           ONSET OF PUBERTY IN GILTS          32

2.7.1        Factors that influence age at onset of puberty in gilts      32

2.7.1.1            Nutritional effect on the puberty attainment in gilts  34

2.7.1.2            Impact of boar exposure on the onset of puberty       35

2.7.1.3            Effect of season on age at puberty     35

2.8    CONDITION SCORING IN PIG PRODUCTION 36

2.8.1                Body condition at breeding    38

2.8.2                Body condition at farrowing  39

2.8.3                Body condition at weaning    39

2.9    MEASURING BACKFAT    39

2.9.1                Backfat thickness and reproductive performance in sow       40

2.9.2                Backfat thickness and body lipid       41

2.10 MILK PRODUCTION OF SOW DURING LACTATION            42

2.10.1             Estimating milk production    44

2.11 SOME MEASURES OF REPRODUCTIVE PERFORMANCE IN FEMALE PIGS        45

2.11.1             Litter size        45

2.11.1.1         Some factors that determine the size of weaned litter           46

2.11.2             Number of parity        46

2.11.3             Age at weaning           46

2.11.3.1         Advantages of early weaning 49

2.11.4             Liveweight at weaning           49

2.11.5             Litter birth weight       49

2.11.6             Piglet mortality           50

2.11.7             Weaning-to-estrus interval      51

2.11.7.1         Physiological explanation for prolonged weaning-to-estrus interval  52

CHAPTER THREE 54

MATERIALS AND METHODS    54

3.1    Location and duration of study          54

3.2    Management of experimental animals            54

3.3    Experimental diets      54

3.4    Experimental design   56

3.5    Statistical design         60

CHAPTER FOUR    64

RESULTS     64

EXPERIMENT I    64

4.1    EFFECT OF DIETARY ENERGY AND PROTEIN ON THE GROWTH AND REPRODUCTIVE PERFORMANCE OF GILTS       64

4.1.1                The effect of dietary treatments on some reproductive and growth indices of gilts 64

4.1.1.1            Age at first oestrus      64

4.1.1.2            Body weight at first oestrus   65

4.1.1.3            Daily feed intake        65

4.1.1.4            Growth rate     66

4.1.1.5            Feed conversion ratio  66

4.1.1.6            Backfat thickness        67

4.1.1.7            Body condition score (BCS)  67

4.1.2                Relationship between age at first oestrus, and body weight at first oestrus, growth rate, backfat thickness and BCS  77

4.1.3                Effect of dietary energy and protein on weight of reproductive organ, weight of ovary and ovulation rate  78

4.1.3.1            Weight of reproductive organ            78

4.1.3.2            Ovarian weight           78

4.1.3.3            Number of corpus luteum (ovulation rate)      79

4.1.4                Relationship between weight of reproductive organ, ovarian weight and number of corpus luteum        82

4.2    EFFECT OF VARYING ENERGY, PROTEIN AND ENERGY X PROTEIN INTERACTION ON THE HAEMATOLOGICAL INDICES OF GILTS     84

4.2.1                Packed cell volume     84

4.2.2                Haemoglobin concentration    84

4.2.3                Red blood cell 85

4.2.4                White blood cell          85

4.2.5                Mean corpuscular volume       85

4.2.6            Mean corpuscular haemoglobin concentration            86

4.2.7            Mean corpuscular haemoglobin          86

4.2.8                Bilirubin          86

4.2.9            Aspartate transaminase or serum glutamic oxaloacetic acid (SGOT) 87

4.2.10          Alanine transaminase or serum glutamic pyruvic acid (SGPT)           87

4.2.11             Alkaline phosphatase  87

4.3    Effect of dietary energy and protein levels on linear body measurements of gilts at first oestrus     91

4.3.1.1            Body length    91

4.3.1.2            Heart girth       91

4.3.1.3            Flank-to-flank 91

4.3.1.4            Height at withers        92

4.3.2                Relationship between body weight and linear body measurements of gilts   95

EXPERIMENT II  97

4.4    Effect of body condition on the reproductive performance of gilts  97

4.4.1.1            Gestation length          97

4.4.1.2            Gestation body weight gain    97

4.4.1.3            Gestation backfat gain            97

4.4.1.4            Backfat of gilts at farrowing  97

4.4.1.5            Lactation body weight loss     98

4.4.1.6            Lactation backfat loss 98

4.4.1.7            Sow 21 day milk production  98

4.4.1.8            Weaning-to-oestrus interval    99

4.4.2                Effect of body condition of gilts on litter performance         101

4.4.2.1            Average litter size at birth       109

4.4.2.2            Average litter size at weaning 102

4.4.2.3            Average piglet birth weight    102

4.4.2.4            Average piglet weaning weight          102

4.4.2.5            Average piglet growth rate     102

4.4.2.6            Percent survival to weaning    103

4.4.2.7            Pre-weaning piglet mortality   103

CHAPTER FIVE     106

DISCUSSION           106

EXPERIMENT I    106

5.1   Effect of dietary energy and protein on the attainment of puberty in gilts    106

5.2   Effect of dietary energy and protein on haematological and biochemical indices of gilts     115

5.3   Effect of dietary energy and protein level on linear body measurements of gilts at first oestrus      116

5.3.1            Relationship between body weight and linear body measurements of gilts   117

EXPERIMENT II  118

5.4    Effect of body condition at mating on the reproductive performance of gilts and pre-weaning growth of their piglets          118

5.5          Summary and conclusion  126

REFERENCES…………………………………………………………………………………128

 

LIST OF TABLES

Tables                                                                                                                                                         Page

Table 1: Nutrient requirement of pigs as reported by different authors     17

Table 2: The influence of premating feed intake on subsequent litter size and piglet performance           21

Table 3: Recommended feeding levels of sow/gilt during various stages of gestation      29

Table 4: Average age at onset of puberty of gilts as reported by various authors  33

Table 5: Relationship between body condition score and backfat thickness         38

Table 6: Relationship between backfat body condition and feeding intake          38

Table 7: The effect of litter size on milk yield in the sow  44

Table  8: Estimation of milk production (M), milk dry matter (DML), Energy (EL) and Nitrogen (NL) output of gilts during a 21day lactation         45

Table 9: Weaning ages of piglets as reported by various authors in different countries    48

Table 10: Percentage composition of experimental diets…………………………………………55

Table 11: Proximate composition of experimental diets…………..………………………………56

Table 12: Relationship between body condition score and ultrasonic backfat levels         57

Table 13: Pre-mating body condition score and backfat groups    59

Table 14: Percentage composition of diet used during gestation and lactation     59

Table 15: Proximate Composition of Gestation and Lactation Diets………………………………………59

Table 16: Analysis of variance of energy and protein effects on age at first oestrus, weight at oestrus, growth rate, backfat reserve and body condition score (BCS)   68

Table 17: Least square means (±SE) of the effects of energy and protein interaction on age at first oestrus, BW at first oestrus, growth rate, backfat reserves and body condition score       69

Table 18: Pearson correlation coefficients between age and body weight at first oestrus, growth rate, backfat thickness and body condition score            78

Table 19: Analysis of variance of energy and protein effects on weight of reproductive organs, and number of corpora lutea.          80

Table 20: Least square means (±SE) of the effects dietary treatments on weight of reproductive   organ, ovarian weight and number of corpora lutea of gilts at first oestrus…………………………………………………………………………………………………………..81

Table 21: Pearson correlation coefficient between weight of reproductive organ, ovarian weight and number of corpora lutea           83

Table 22: Analysis of variance of energy, protein and energy x protein interaction on the haematological indices of gilts 89

Table 23: Least square means (±SE) of the effect of dietary treatments (energy and protein) on the haematological indices of gilts         90

Table 24: The analysis of variance of energy and protein effects on linear body measurements of gilts at first oestrus         93

Table 25: Least square means ± SE of the effects of energy and protein interaction on linear body measurements of gilts at first oestrus         94

Table 26: Correlation coefficients showing interrelationships between various measurements and body weight (kg)        96

Table 27: Relationship between live weights and linear measurements of pigs     96

Table 28: Stepwise multiple regression prediction of body weight from body measurements; regression coefficients.            96

Table 29: Analysis of variance and descriptive statistics of the effect body condition on reproductive performance of sow         100

Table 30: Effect of Duncan mean on the reproductive performance of sows with different body condition       101

Table 31: Analysis of variance of the effect of body condition on litter performance      104

Table 32: Effect of Duncan mean on the litter performance of gilts with different body condition         105

 

LIST OF FIGURES

Figures                                                                                                                                      Page

Fig. 1: Interaction of energy and protein on average age at first oestrus of gilts            70

Fig. 2: Interaction of energy and protein on average body weight of gilt at first oestrus           71

Fig. 3: Interaction effect of energy and protein on average daily feed intake     72

Fig. 4: Interaction of energy and protein on average growth rate of gilts at first oestrus          73

Fig. 5: Interaction of energy and protein on average feed conversion ratio of gilts at first oestrus      74

Fig. 6: Interaction of energy and protein on average backfat thickness of gilts at first oestrus            75

Fig. 7: Interaction of energy and protein on average body condition score of gilts at first oestrus       76

CHAPTER ONE

1.1       Introduction

Recent report (Spore, 2007) showed that pork is the world most widely consumed meat making up about 40 per cent of the total meat consumed worldwide. The high pork consumption has been attributed to the high cost of beef and the fear of avian influenza for poultry (Spore, 2007). In Africa, however, it barely accounts for 10% of meat consumed. From 1990 to 2005, its production has risen from 500,000 to 800,600 tonnes, probably as a result of rapid urbanization which interestingly has boosted production (Spore, 2007). In Nigeria, FAO (2005) reported a 4 per cent increase in the annual growth rate for pig production from 1990 to 2000 and this was adjudged to be the highest among other livestock species.

These reports are an indication that swine production has the potential for bridging the protein deficiency gap in this country. This is because pigs are endowed with natural genetic potentials that support rapid growth and high reproductive performance. For instance, pigs have a rapid growth rate and demonstrate excellent capacity for reproduction being litter-bearing in nature (Holness, 2005). They are characterized also by the best efficiency of nutrient transformation into high quality animal protein (Spore, 2007). These attributes have not been completely harnessed in this country thus leading to the slow increase in the supply of pork.

The performance of the breeding herd is fundamental to the financial success of any pig enterprise. According to White (1996) and Whittemore (1998), pig production is often assessed based on the number of litters produced per sow per year, the number of piglets produced per litter, and the viability of those piglets. Also, the lifetime productivity of the female within the herd is taken into account. Thus, the young gilt represents the future of any pig enterprise and if not fed properly, is unlikely to achieve her reproductive potential of rearing 60 to 70 pigs over 6 to 7 parities (Scharlach, 1998). It is therefore necessary to provide gilts with adequate nutrition in order to maximize litter growth rate, and minimize empty sow-days thus increasing the size of subsequent litters. Good nutritional preparation of the gilt from selection to first farrowing is essential in achieving this goal. Soede et al. (2007) reported that good nutritional management of gilts makes them to be mature, well grown and in good body condition at service, resulting in better conception rate and litter numbers. They emphasized that far too many gilts are weaned in poor condition and do not conceive or have poor second litters leading to an inexcusable waste of breeding potential.

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