1 Kirkden, R.D., Broom, D.M. and Andersen, I.L. 2013. Piglet mortality: 2 management solutions. Journal of Animal Science, 91, 3361-3389. 3 DOI: 10.2527/jas.2012-5637 4 Pre-publication copy. 5 Piglet mortality: management solutions1 6 7 8 9 R. D. Kirkden*, D. M. Broom* and I. L. Andersen† 10 11 *University of Cambridge, Department of Veterinary Medicine, Madingley Road, 12 Cambridge, CB3 0ES, UK 13 †Norwegian University of Life Sciences, Department of Animal and Aquacultural 14 Sciences, PO Box 5003, 1432 Ås, Norway 15 16 1The authors wish to thank: Dan Tucker for advice on disease in sows and piglets; Sandra 17 Edwards and Emma Baxter for a general discussion of piglet mortality, housing and 18 management; and six farrowing industry professionals in the UK (producers, herd 19 managers and consultants) for discussion and for allowing the first author to visit their 20 facilities. 21 22 Corresponding author: Richard Kirkden. E-mail: [email protected]. 23 24 Running head: Piglet mortality: management solutions 25 1 26 Keywords: farrowing, lactation, management, welfare, mortality, pig, swine 27 28 ABSTRACT 29 30 31 Pre-weaning mortality varies greatly among herds and this is partly attributed to 32 differences in farrowing house management. In this review, we describe the various 33 management strategies than can be adopted to decrease mortality and critically examine 34 the evidence that exists to support their use. First, we consider which management 35 procedures are effective against specific causes of death: intrapartum stillbirth, 36 hypothermia, starvation, disease, crushing and savaging. The most effective techniques 37 include: intervention to assist dystocic sows; measures to prevent and treat sow 38 hypogalactia; good farrowing house hygiene; providing newborn piglets with a warm 39 microenvironment; early fostering of supernumerary piglets; methods that assist small 40 and weak piglets to breathe and obtain colostrum; and intervention to prevent deaths from 41 crushing and savaging. The provision of nest-building material and modifications to the 42 pen to assist the sow when lying down may also be beneficial, but the evidence is less 43 clear. Because most deaths occur around the time of farrowing and during the first few 44 days of life, the periparturient period is a particularly important time for management 45 interventions intended to reduce piglet mortality. A number of procedures require a 46 stockperson to be present during and immediately after farrowing. Secondly, we consider 47 the benefits of farrowing supervision for pre-weaning mortality in general, focusing 48 particularly on methods for the treatment of dystocia and programs of piglet care that 2 49 combine multiple procedures. Thirdly, we discuss the need for good stockmanship if 50 farrowing supervision is to be effective. Stockmanship refers not only to technical skills, 51 but also to the manner in which sows are handled because this influences their fearfulness 52 of humans. We conclude that piglet survival can be improved by a range of management 53 procedures, many of which occur in the perinatal period and require the supervision of 54 farrowing by trained staff. Although this incurs additional labor costs, there is some 55 evidence that this can be economically offset by improved piglet survival. 56 57 INTRODUCTION 58 59 60 In European and North American major pig-producing countries, liveborn pre-weaning 61 mortality is typically in the region of 11-13%, with a further 7-8% of piglets being 62 stillborn (British Pig Executive, 2011; PigCHAMP, 2011). Mortality varies greatly 63 among herds, with a live-born mortality rate of 5-7% (Lawlor and Lynch, 2005; 64 Andersen et al., 2007) and a stillbirth rate of <5% (Muirhead and Alexander, 1997) being 65 achievable. Many factors contribute to variability between farms, including genotype, 66 housing, nutrition and management. In this review, we focus on the role of management. 67 Housing has been reviewed recently (Baxter et al., 2012). 68 69 The review begins by describing management factors that are relevant to particular types 70 of mortality (intrapartum stillbirth, hypothermia, starvation, disease, crushing and 71 savaging). The next section focuses on the benefits of farrowing supervision, considering 3 72 how assisting the sow and her litter can help to reduce multiple types of mortality. In the 73 final section, we discuss the need for good stockmanship if farrowing supervision is to be 74 effective. In a separate paper (Kirkden et al., 2013), we consider the induction of 75 parturition using prostaglandins and oxytocin as a means to facilitate the supervision of 76 farrowing. 77 78 We have comprehensively reassessed the evidence concerning the effects of management 79 factors on piglet mortality. The literature is large, with many studies conducted as early 80 as the 1970s and 1980s still being relevant today. We conclude that a given management 81 procedure is effective only when the majority of experimental papers support this. Where 82 reviewers have made statements or recommendations that are based on practical 83 experience rather than experimental work, we accept these provisionally as expert 84 opinions unless they are contradicted by published data. For all experimental studies 85 using statistical analyses, only findings where P < 0.05 are considered significant. In the 86 absence of statistical analyses, only very large and consistent numerical differences are 87 accepted as evidence of an effect. All claims made by authors or reviewers have been 88 checked against the results of the studies in question. In some cases, these strategies have 89 led us to report results different from those claimed. 90 91 IMPORTANCE OF MANAGEMENT 92 93 4 94 Andersen et al. (2007) surveyed 39 small Norwegian farms with similar genetic stock and 95 physical environments and reported that live-born mortality ranged from 5-24%, 96 suggesting that management was an important factor. As litter size continues to increase 97 due to the use of more prolific sows, there is an ever greater need for good management 98 practices and skilled stockmanship to keep mortality levels down (English, 1993a). Also 99 in loose housing systems, where the sow’s behavior is much less restricted than in a 100 farrowing crate, a combination of breeding, management and housing strategies to 101 modify sow behavior and improve piglet vitality is likely to be important (Edwards, 102 2002; Andersen et al., 2007; Baxter et al., 2011). 103 104 Most deaths occur around farrowing and during the first few days of life (e.g. Cronin et 105 al. 2000; Marchant et al. 2000). Therefore, the periparturient period is a particularly 106 important time for management interventions intended to reduce piglet mortality. 107 108 At present, management strategies commonly focus on: measures to control disease, such 109 as hygiene, all-in all-out procedures, medication and monitoring herd disease status; 110 fostering of piglets to limit litter size; provision of a suitable thermal environment for the 111 piglets; and feeding the sow to maximize milk production (Kingston, 1989; Lay et al., 112 2002). These are all important aspects of management. However, several authors have 113 argued that they are not sufficient to reach the low levels of mortality, in the region of 114 5%, that are being achieved by a minority of producers (English and Wilkinson, 1982; 115 Kingston, 1989; Cutler et al. 2006). To do so, it is often recommended that the sow 116 should be supervised and if necessary assisted during farrowing and that special care 5 117 should be provided for small and weak piglets during the first few days of life (English 118 and Morrison, 1984; England, 1986; Kingston, 1989; Hughes, 1992; Vaillancourt and 119 Tubbs, 1992; English, 1993a; Muirhead and Alexander, 1997; Tuchscherer et al., 2000). 120 Some authors also recommend measures to minimize the sow’s level of stress around the 121 time of farrowing, for example the provision of straw to permit nest-building (Hughes, 122 1992; Fraser et al., 1995; Cutler et al., 2006) and the development of a positive 123 relationship between the stockperson and the sow in order that she is not fearful of human 124 contact (Kingston, 1989; English et al., 1999; Hemsworth et al., 1995, 1999). In this 125 review we examine the evidence that exists to support such management strategies. 126 127 INTRAPARTUM STILLBIRTH AND LOW VITALITY 128 129 130 Intrapartum stillbirth, low viability in the immediate postnatal period, low vitality during 131 the first few days of life and postnatal mortality are closely linked. Perinatal asphyxia is 132 the proximate cause in most cases of stillbirth and also results in reduced viability and 133 vitality, both of which increase the risk of postnatal mortality (reviewed by: Hughes, 134 1992; Herpin et al. 1996, 2002; Edwards, 2002; Alonso-Spilsbury et al. 2007). Dystocia, 135 defined as difficult parturition to the point of needing human intervention (Blood and 136 Studdert, 1999) is recognized as a risk factor for stillbirth (Jackson, 1975). The rate of 137 stillbirth is frequently reported to be greatest in high parity sows, probably due to 138 dystocia caused by fatness or poor uterine muscle tone (Bille et al., 1974a; Pejsak, 1984). 139 6 140 141 Management strategies 142 143 Management strategies to reduce stillbirth and improve piglet viability and vitality are 144 aimed at (1) reducing the duration of farrowing, or the time taken to deliver individual 145 piglets and (2) providing weak piglets with assistance immediately after birth. Thus, 146 common recommendations include: culling old sows (English and Wilkinson, 1982; 147 Hughes, 1992); ensuring that sows are not excessively fat at farrowing (Oliviero et al., 148 2010); attending farrowings and providing assistance to sows experiencing dystocia 149 (Hughes, 1992; Zaleski and Hacker, 1993b; Herpin et al., 1996; Lucia et al., 2002; Cutler 150 et al., 2006; Fangman and Amass, 2007), focusing particularly on high parity sows and 151 sows expected to have large litters (Borges et al., 2005); minimizing disturbances that 152 might cause stress during farrowing (Fangman and Amass, 2007); helping weak piglets to 153 establish breathing (Herpin et al., 1996); assisting weak piglets to reach the udder, or 154 feeding them artificially (Herpin et al., 1996); and keeping weak piglets warm (Herpin et 155 al., 1996). The induction of farrowing using prostaglandins is often recommended to 156 facilitate supervision (Sprecher et al., 1974; Herpin et al., 1996; Cutler et al., 2006). 157 158 Effective procedures for assisting dystocic sows include manual intervention to reposition 159 or extract piglets in the birth canal and oxytocin injection to stimulate uterine contraction. 160 There are risks associated with these procedures if they are not carried out correctly and 161 we discuss them in more detail later (see Supervision of farrowing: Assisting the sow 162 during farrowing). The evidence that a high level of farrowing supervision reduces 7 163 stillbirth rate is mixed (see Supervision of farrowing: Multiple procedures), probably 164 because much of it derives from observational studies that have compared farms without 165 information about the type or quality of supervision. However, several controlled 166 experimental studies that have implemented supervision protocols including care for the 167 sow and the litter have reported a reduction in stillbirths and pre-weaning mortality (see 168 Supervision of farrowing: Multiple procedures). 169 170 Stress during farrowing causes the production of opioids, which inhibit oxytocin and can 171 prolong farrowing (Lawrence et al., 1992). Disturbances that might cause stress include 172 loud or sudden noises and disruptive activities such as processing the piglets of 173 neighboring sows (Fangman and Amass, 2007). Even routine management practices such 174 as feeding and cleaning can cause sufficient disturbance to delay farrowing (Welp and 175 Holtz, 1985). Although increased piglet mortality has not been demonstrated in these 176 cases, the risk of perinatal asphyxia is known to increase with birth interval (Stanton et 177 al., 1973). In 1 study, high levels of abortion and stillbirth occurred during a period when 178 nearby construction work was causing sudden and very loud noises (Kim et al., 1999). 179 180 The provision of bedding material to permit nest-building behavior before farrowing may 181 act to reduce stress and some studies have reported a positive effect on farrowing 182 duration and stillbirth rate in young sows (Cronin et al., 1993; Thodberg et al., 2002), 183 although others have not (Edwards and Furniss, 1988; Cronin and van Amerongen, 1991; 184 Cronin and Smith, 1992). Fraser et al. (1997) reviewed the effects of providing bedding 185 or increased space or both on stillbirth rate and concluded that the findings have been 8 186 inconsistent. Transferring the sow to farrowing accommodation early, to give her time to 187 habituate before farrowing, should help to reduce stress, but again there is no evidence 188 that this reduces stillbirth levels (Vanderhaeghe et al., 2010b). 189 190 Heat stress in late gestation may be a risk factor for stillbirth. Again, observational 191 studies have had mixed findings (Odehnalová et al., 2008; Vanderhaeghe et al., 2010a,b). 192 Experimental studies have shown an increased stillbirth rate when a temperature of 38°C 193 was imposed on d 102-110 of gestation (Omtvedt et al., 1971), but not when a 194 temperature of 27°C was applied from d 110 until after farrowing (Lynch, 1977). Hence, 195 it may be that stillbirths are only increased when ambient temperature is very high. 196 Maintaining the farrowing house temperature below 29°C (Sprecher et al., 1974), or 197 cooling sows in hot weather (Cutler et al., 2006) have been recommended. 198 199 Procedures that have been used to help weak piglets establish breathing include clearing 200 the throat and nostrils of mucous (Milosavljević et al., 1972; White et al., 1996; Muirhead 201 and Alexander, 1997), administering oxygen using a face mask or chamber (White et al., 202 1996; Herpin et al., 2001) and artificial ventilation (Milosavljević et al., 1972). It has 203 been suggested that merely handling weak piglets, for example when drying them, may 204 act to stimulate respiration (White et al., 1996), although there is currently no evidence 205 for this. Oxygen administration also improves the vitality of small piglets which do not 206 show difficulty breathing (Herpin et al., 2001). Administering oxygen to all piglets in this 207 study decreased mortality on the first day of life by 75%. 208 9 209 Other procedures are aimed at preventing hypothermia, starvation and dehydration in 210 small and weak piglets until they are strong enough to compete at the udder. They 211 include: drying; placing under a heat lamp, or in a heated cradle; placing at the udder; and 212 administering colostrum, milk replacer, or fluids. These methods will be described later, 213 in the sections on hypothermia (see Reduction of heat loss) and starvation (see Piglet 214 care). 215 216 HYPOTHERMIA 217 218 219 The ambient temperature of the farrowing house is normally below the newborn piglets’ 220 lower critical temperature (Herpin et al. 2002), so they must initially use their energy 221 reserves to maintain body temperature (Elliot and Lodge, 1977), and it is essential that 222 they obtain colostrum promptly if they are to avoid hypothermia or starvation (Le 223 Dividich and Noblet, 1981; Herpin et al., 1994). Low birthweight individuals are most at 224 risk due to low energy reserves and a poor ability to compete at the udder (reviewed by 225 Herpin et al. 2002). 226 227 228 Heat provision 229 230 The litter must be provided with a warm microenvironment. In natural conditions, the 231 sow builds a nest and neither the sow nor the piglets normally leave the nest during the 10