Richard D Kirkden

Pre-weaning mortality varies greatly among herds and this is partly attributed to differences in farrowing house management. In this review, we describe the various management strategies than can be adopted to decrease mortality and critically examine the evidence that exists to support their use. First, we consider which management procedures are effective against specific causes of death: intrapartum stillbirth, hypothermia, starvation, disease, crushing and savaging. The most effective techniques include: intervention to assist dystocic sows; measures to prevent and treat sow hypogalactia; good farrowing house hygiene; providing newborn piglets with a warm microenvironment; early fostering of supernumerary piglets; methods that assist small and weak piglets to breathe and obtain colostrum; and intervention to prevent deaths from crushing and savaging. The provision of nest-building material and modifications to the pen to assist the sow when lying down may also be beneficial, but the evidence is less clear. Because most deaths occur around the time of farrowing and during the first few days of life, the periparturient period is a particularly important time for management interventions intended to reduce piglet mortality. A number of procedures require a stockperson to be present during and immediately after farrowing. Secondly, we consider the benefits of farrowing supervision for pre-weaning mortality in general, focusing particularly on methods for the treatment of dystocia and programs of piglet care that combine multiple procedures. Thirdly, we discuss the need for good stockmanship if farrowing supervision is to be effective. Stockmanship refers not only to technical skills, but also to the manner in which sows are handled because this influences their fearfulness of humans. We conclude that piglet survival can be improved by a range of management procedures, many of which occur in the perinatal period and require the supervision of farrowing by trained staff. Although this incurs additional labor costs, there is some evidence that this can be economically offset by improved piglet survival.

The price and income elasticities of demand have been used by ethologists to estimate motivationalstrength. The consumer surplus is an alternative measure of motivation, deriving from microeconomic theory. We made a theoretical assessment of the validity and versatility of these indices. Two factors are expected to compromise the internal validity (veracity) of the elasticity of demand indices: failure to take into account the amount that an animal is required to pay to maintain some level of consumption; and a tendency to confuse its readiness to defend a preferred consumption level with a propensity to becomesatiated. A third factor, expected to compromise the external validity (usefulness) of these indices, is theunrealistic assumption that a single value can be assigned to each resource. None of these problems applies to the consumer surplus index. One further factor, expected to compromise the internal validity of both the consumer surplus and price elasticity indices, is their failure to account for the effects that income has upon consumption. Overall, we conclude that the consumer surplus should be more valid,both internally and externally, than the price elasticity index. The consumer surplus should also be more externally valid than the income elasticity index, but it is unclear, on balance, which of these indices is the more internally valid. Finally, we show that both elasticity indices are considerably less versatile than the consumer surplus, owing to the assumption that a single value can be assigned to each resource.

Leg disorders in broilers are a major economic and welfare problem. The aetiology of many disorders is complex but includes genetics, growth rate (due to feed restriction or lighting regime), feed conversion efficiency and body conformation, exercise, circadian rhythms, nutrition and stocking density. These categories are not mutually exclusive as one aetiological factor may affect another. Many studies of leg disorders fail to identify the specific pathological condition underlying the observed lameness. However, disorders may be classified according to underlying pathology as infectious, developmental and degenerative. This classification is difficult because these categories are not mutually exclusive. Infectious conditions include bacterial chondronecrosis with osteomyelitis (BCO or femoral head necrosis, FHN), tenosynovitis and arthritis, infectious stunting syndrome (ISS) and viral induced neoplasia. Developmental conditions include varus valgus disease (VVD), rotated tibia, tibial dyschondroplasia (TD), rickets, chondrodystrophy and spondylolisthesis. Degenerative disorders include osteochondrosis (often TD), epiphyseolosis (often classified as FHN), degenerative joint disease (DJD), spontaneous rupture of the gastrocnemius tendon and contact dermatitis. BCO, TD, dermatitis and VVD are the most common disorders. Outbreaks of leg disorders are often site / context specific. The welfare of broilers with leg disorders may be impaired due to pain from the condition, an inability to walk leading to frustration and associated problems of being unable to feed and drink due to immobility (which may result in starvation). In assessing welfare, the individual broiler must be considered irrespective of the frequency of occurrence of the disorder. Most studies of welfare in relation to leg disorders have used a subjective gait scoring method (0 is normal walking and 5 is unable to walk). Gait scoring is a practical method for assessing broiler lameness in the field. The method provides a useful tool to employ in the field without recourse to pathological investigation and, while the method conflates conformity with pathology, it is a helpful and constructive additional method to assist in welfare studies. For birds with scores greater than 3, lameness may be viewed as severe enough to potentially impair welfare. It is difficult to assess all disorders in relation to frequency of occurrence and their impact on welfare due lack of evidence. BCO (or FHN and BCN) is the most common disorder and is often severe in form. TD (incl. epiphyseolysis) and rickets is common, often sub-clinical but when severe is a considerable impact on welfare. Contact dermatitis may be common under certain conditions and causes poor welfare when severe. Gastrocnemius tendon slippage, tenosynovitis, DJD and spondylolisthesis are not so common but are likely to cause poor welfare when they occur (i.e. pain and prevention of certain behaviours). VVD and rotated tibia can be common but tend not to be directly painful unless another condition is present. However, they can cause poor welfare if the bird is not culled and lead to an inability to walk, feed, drink and perform other behaviours. ISS, viral induced neoplasia and chondrodystrophy have only a small impact on welfare in the UK flock, the last because it is no longer encountered. To decrease the prevalence of leg disorders, growth rate needs to be decelerated: meal feeding, feed restriction during the early period of rearing, lower stocking densities and increased activity can result in a considerable reduction in leg problems. Continuous lighting should be avoided; overall the light period should be reduced. There also needs to be careful management of litter to prevent dermatitis. Factors in the diet are also important, particularly Ca, P and D3 which can prevent certain disorders 2 (e.g. TD). Further research is needed to establish the prevalence of disorders, underlying pathology in relation to subjective gait scores and analgesics in relation to pain mechanisms. A forum for discussion of these issues should be established and further control-trials conducted to investigate these factors.

It is concluded that there are several routes by which poor welfare results in an increase in disease. The pathophysiology of states typified by behavioural abnormalities and emergency physiological responses is a subject which is insufficiently investigated.