Although a few studies consider the sustainability of animal farming systems along the three classical main pillars (economy, environment and society), most studies on pig farming systems address only one of these pillars. The present paper is the introduction to a series of companion papers presenting the results of a study undertaken within the EU-supported project Q-PorkChains, aiming at building a comprehensive tool for the evaluation of pig farming systems, which is robust to accommodate the large variability of systems existing in Europe. The tool is mostly based on questions to farmers and comprises a total of 37 dimensions distributed along eight themes: Animal Welfare, Animal Health, Breeding Programmes, Environmental Sustainability, Meat Safety, Market Conformity, Economy and Working Conditions. The paper describes the procedure that was used for building the tool, using it on 15 contrasted pig farming systems and analysing the results. The evaluated systems are briefly described and a short overview of the dimensions is provided. Detailed descriptions of the theme-wise tools and results, as well as the results of an integrated evaluation, are available in the companion papers.

The aim of this paper is to present an approach for an integrated evaluation of the sustainability of pig farming systems, taking into account the three classical pillars: economy, environment and society. Eight sustainability themes were considered: Animal Welfare (AW), Animal Health (AH), Breeding Programmes (BP), Environment (EN), Meat Safety (MS), Market Conformity (MC), Economy (EC) and Working Conditions (WC). A total of 37 primary indicators were identified and used for the evaluation of 15 much contrasted pig farming systems in five EU countries. The results show that the eight themes were not redundant and all contributed to the observed variation between systems. The tool was very robust for highlighting the strengths and weaknesses of the systems along the eight themes that were considered. The number of primary indicators could be reduced from 37 to 18 with limited impact on the strengths/weaknesses profile of the individual systems. Integrating the eight theme evaluations into a single sustainability score is based on hypotheses or presumptions on the relative weights that should be given to the eight themes, which are very dependent on the context and on the purpose of the users of the tool. Therefore, the present paper does not have the ambition to provide a ready-for-use tool, rather to suggest an approach for the integrated evaluation of the sustainability of pig farming systems.

The sustainability of breeding activities in 15 pig farming systems in five European countries was evaluated. One conventional and two differentiated systems per country were studied. The Conventional systems were the standard systems in their countries. The differentiated systems were of three categories: Adapted Conventional with focus on animal welfare, meat quality or environment (five systems); Traditional with local breeds in small-scale production (three systems) and Organic (two systems). Data were collected with a questionnaire from nine breeding organisations providing animals and semen to the studied farming systems and from, on average, five farmers per farming system. The sustainability assessment of breeding activities was performed in four dimensions. The first dimension described whether the market for the product was well defined, and whether the breeding goal reflected the farming system and the farmers’ demands. The second dimension described recording and selection procedures, together with genetic change in traits that were important in the system. The third dimension described genetic variation, both within and between pig breeds. The fourth dimension described the management of the breeding organisation, including communication, transparency, and technical and human resources. The results show substantial differences in the sustainability of breeding activities, both between farming systems within the same category and between different categories of farming systems. The breeding activities are assessed to be more sustainable for conventional systems than for differentiated systems in three of the four dimensions. In most differentiated farming systems, breeding goals are not related to the system, as these systems use the same genetic material as conventional systems. The breeds used in Traditional farming systems are important for genetic biodiversity, but the small scale of these systems renders them vulnerable. It is hoped that, by reflecting on different aspects of sustainability, this study will encourage sustainable developments in pig production.

The aim of this study was to estimate genetic parameters for feed intake recorded as farmers’ perception of young sows’ appetite for the first 3 weeks of lactation (APP) and feed intake recorded for one day in the 3rd week of lactation (FEED), litter weight (LW) at 3 weeks, sow body condition at weaning (BC) and the following five reproduction traits: weaning-to-service interval of 1 to 7 days (WSI7), weaning-to-service interval of 1 to 50 days (WSI50), delayed service or not (DELAYED), pregnant on first service or not (PREGNANT) and litter size in 2nd parity (NBT2). The analyses included data on 4606 Norwegian Landrace 1st-parity sows and their litters. The Gibbs sampling method was used. The traits DELAYED and PREGNANT were analysed as threshold traits and APP, FEED, LW, BC, WSI7, WSI50 and NBT2 were analysed as linear traits. The heritability estimates for APP and FEED were low (<0.1), whereas the estimates for DELAYED and PREGNANT were rather high (0.4 and 0.3). The heritability estimate for BC was 0.2. The genetic correlations confirmed the complexity of breeding for sow performance; selection for heavy 1st litters may lead to lower body condition at weaning, which in turn leads to lower reproductive performance and smaller litters in 2nd parity. Selection for higher sow feed intake would improve body condition, but the simple way of measuring feed intake tested in this study (APP and FEED) cannot be recommended because of the low heritability obtained for these traits.

In today's production systems, pigs raised for slaughter are mixed many times, resulting in stress and fighting. The negative consequences of mixing are probably more severe with entire males than with castrates, as they fight more. In this project, we studied a system without castration where entire male pigs met unfamiliar pigs only once. Piglets from two litters were allowed to visit each other from circa 2 weeks of age through an opening between the farrowing pens. Entire males from these litters were kept in intact groups from weaning and onwards, and they were slaughtered pen-wise in intact groups. Control pigs were raised and weaned in their litters and mixed with unknown pigs when moved to the growing–finishing unit. They were slaughtered by split marketing based on individual weight. In total, 96 entire males from 24 litters were studied. Activity and social interactions of pigs were studied by direct observations on three observation occasions per pen for pigs kept in intact groups and four occasions for control pigs. All pigs were inspected for skin lesions during raising and at slaughter. Results showed that fewer pigs in intact groups were resting (17.1% v. 28.5%; P = 0.044) and they showed less aggressive behaviour (16.1 v. 27.7 number of interactions per hour; P = 0.001) than control pigs when moved to the growing–finishing unit. They also got fewer skin lesions compared with control pigs (15 v. 35; P < 0.001). Consequently, control pigs tended to grow slower during the 1st week after mixing; however, growth rate during the whole growing–finishing phase did not differ between treatments (P = 0.205). Control pigs directed more aggressive behaviour towards non-litter mates than towards litter mates during the whole growing–finishing phase, whereas pigs from the other treatment made no difference between litter mates and other familiar pigs. At 67 kg, there was more sexual behaviour (mounting) among control pigs (7.6 v. 3.4; P = 0.033), but after slaughter no differences were found in testis weight or boar taint compounds. At slaughter, more entire males that were slaughtered pen-wise and kept in intact groups were without skin lesions compared with the mixed control pigs (74% v. 13%; P < 0.001). This study shows that the welfare of entire male pigs can be improved by socialising piglets and by keeping them in intact groups during raising and at slaughter.

The objective of this paper was to estimate the heritability for shoulder ulcers and the genetic correlations between shoulder ulcers, mean piglet weight and sow body condition. The analyses were based on information on 5549 Norwegian Landrace sows and their 7614 purebred litters. The genetic analysis was performed using the Gibbs sampling method. Shoulder ulcers were analyzed as a threshold trait. Sow body condition and mean piglet weight were analyzed as linear traits. The heritability of shoulder ulcers was estimated at 0.25 (s.d. = 0.03). The heritability for sow body condition was estimated at 0.14 (s.d. = 0.02) and that for mean piglet weight at 0.23 (s.d. = 0.02). The genetic correlation between shoulder ulcers and sow body condition was negative (−0.59, s.d. = 0.09). The genetic correlation between shoulder ulcers and mean piglet weight was positive (0.23, s.d. = 0.10) and the genetic correlation between sow body condition and mean piglet weight was negative (−0.24, s.d. = 0.10).

The aim of this study was to evaluate the effectiveness of a gonadotropin-releasing hormone (GnRH) vaccine, Improvac™ (Pfizer Ltd), in suppressing aggressive and sexual behaviour of male pigs. One hundred and thirty-six pigs were assigned to three treatments: entire male pigs (n = 64), immunocastration against GnRH (n = 48) and surgical castration (n = 24). Surgical castration was performed before the age of 1 week. Vaccination comprised two injections: the first injection was given 8 to 11 weeks before slaughter and the second injection 4 weeks before slaughter. After the second injection, immunocastrated pigs showed less non-violent social and aggressive behaviours than entire male pigs of the same age. Mounting was reduced to the same low level as observed in surgically castrated pigs, and more immunocastrated pigs were without skin lesions compared with entire male pigs. Pigs that received the second injection only 1 week before the observation day did not differ significantly in behaviour from those that received the injection 3 weeks before the observation day. Thus, the behaviour seems to change soon after the second injection and these changes remain until slaughter.

The present study investigated the presence of a single-nucleotide polymorphism (G > T) at base −8 upstream of ATG in 5′ untranslated region of cytochrome b5 (CYB5A) gene in Swedish pig populations and evaluated the significance of this polymorphism for androstenone and skatole levels, sexual development and performance parameters in pigs. Frequencies of the T allele were 6.7% for Swedish Yorkshire × Landrace crossbred pigs (n = 245), 6.5% for Swedish Yorkshire (n = 99) and 12.8% for Landrace breed (n = 74). No deviations from Hardy–Weinberg equilibrium were observed in the investigated populations. In Swedish Yorkshire × Landrace crossbred entire male pigs (n = 193), plasma samples were analysed for skatole, androstenone, testosterone and oestrone sulphate, and fat samples were analysed for androstenone, skatole and free oestrone. Additionally, testis weight and bulbourethral gland length for crossbred pigs were recorded. Plasma androstenone levels were significantly lower in the G/T genotype at 90 kg live weight compared with the wild G/G genotype at the same live weight (P = 0.006). In heavier pigs, plasma androstenone levels did not differ between genotypes (P = 0.382). Fat androstenone levels were not affected by CYB5A genotype (P = 0.252). Skatole levels in the G/T genotype at 115 kg live weight were lower compared with those in the G/G genotype in plasma (P = 0.048) and fat (P = 0.028), although no differences were observed in lighter pigs. Testis weight, bulbourethral gland length, testosterone and oestrone sulphate levels in plasma, and oestrone levels in fat were not affected by genotype. We concluded that the presence of the T allele in the CYB5A gene resulted in lower androstenone levels in plasma, and lower skatole levels in fat and plasma; this reduction, however, was dependent on the live weight of the animals. Reproductive hormones and growth rate did not differ between the pigs of different genotypes, whereas a higher lean meat content was found in the G/T genotype in comparison with the G/G genotype. The practical application of those results in Sweden is doubtful because of lack of the effect on androstenone in fat and the low frequency of the T allele in the studied Swedish pig populations.

The objective of the study was to estimate genetic trends from 1977 to 1998 in the French Large White (LW) breed for stillbirth and associated traits measured at farrowing using frozen semen. Two groups of pigs (G77 and G98) were obtained by inseminating LW sows with semen from LW boars born either in 1977 or in 1998. A second generation was produced by inter se mating in each group. Farrowing was thoroughly supervised through both direct observations and video recording all long farrowing on a total of 137 first- and second-parity litters produced by sows from this second generation (68 G77 and 69 G98 litters, respectively). Measurements included birth time, weight and birth characteristics (including orientation, presence of cyanosis or oedema, membrane obstruction, umbilical cord length/content) of each piglet, as well as sow traits (weight and backfat thickness, farrowing duration, litter size and within-litter variation of weights at birth). The data were analysed using linear or generalised linear mixed models, according to the definition of the trait (continuous or binary data). The importance of several effects to piglet probability of stillbirth was then quantified by computing the reduction of variance associated with the addition of each effect in the model. Litter size did not significantly differ in first parity, but was higher in G98 second-parity sows: the differences for global (including pre partum dead piglets) and total numbers of piglets born per litter were +2.3 ± 1.1 and +1.3 ± 0.6, respectively. G98 sows also had a higher number of stillbirths in both parities (+0.7 ± 0.3 stillborn per litter). Piglets from G98 litters were heavier at birth (+130 ± 40 g for birth weight adjusted for litter size), without any increase in within-litter heterogeneity of birth weight. No significant difference was detected between G77 and G88 groups for farrowing length and the distribution of time interval between piglet births. G98 stillborn piglets had longer and more often empty umbilical cords at birth. G98 piglets born alive also had more often umbilical nodes than G77 piglets. These characteristics were considered as indicators of increased farrowing difficulties and risk of hypoxia at birth in G98 pigs. Time of birth of each piglet, sow fatness at farrowing and time of first placenta expulsion were the main factors of variation of the piglet’s probability of stillbirth.

A study seeking to estimate phenotypic and genetic parameters for sow body condition around lactation and their relationship with piglet growth and survival is described. It also investigates the genetic relationship between piglet growth and survival, including both direct and maternal effects for both traits. Records were available from 24 549 Swedish Yorkshire piglets born in 2198 litters. Sows had records of weight and backfat depth at farrowing and at weaning. Piglets had individual records for weight at birth and weaning and cause of death for those that failed to survive during lactation. Mixed linear bivariate models were used to estimate correlations between traits. The models for the sow traits took into account the random effects of permanent environment and the genetic effect of the sow, whereas the models for the piglet traits included a litter effect as well as direct and maternal genetic effects. Estimated heritabilities for sow weight and backfat at farrowing and change of weight and backfat during lactation were low to moderate (0·10 to 0·47). We found significant genetic correlations between change of weight and backfat during lactation and piglet survival and growth, indicating that sows with the genetic capacity for rapid early piglet growth and high survival rate may lose more body reserves during lactation. Negative direct-maternal correlations for early piglet growth and survival imply that both the piglet and the sow trait should be included in a genetic evaluation for these traits. Genetic correlations between piglet survival and growth were not clearly favourable. Selection for the direct effect of piglet survival may lead to a decrease in early growth rate. We conclude that in a selection programme aiming at improving piglet survival and growth, attention should be paid to the sow's body condition during lactation. A high enough level of body reserves needs to be maintained in the sow if the incidence of reproductive problems and involuntary culling is not to increase.

The objective of this study was to analyse the relationship between direct and maternal genetic effects on litter size and piglet survival. The analyses were performed on records from 26 564 Landrace litters and 15 103 Yorkshire litters from first parity dams in Finnish herds. The trivariate model fitted total number of piglets born, proportion alive at birth and proportion survived from birth until 3 weeks as traits of the litter. The model included direct genetic and maternal genetic effects for all traits. In Landrace pigs, maternal heritabilities were estimated to be 0·11 for total number born, 0·06 for proportion alive at birth, and 0·08 for proportion survived from birth until 3 weeks. The corresponding estimates for the Yorkshire breed were 0·14, 0·06 and 0·01. All heritability estimates of direct effects were below 0·05. In the Landrace breed, there was a negative correlation of -0·39 between maternal genetic effects on total number born and maternal genetic effects on proportion survived from birth until 3 weeks and a negative correlation of -0·41 between direct and maternal genetic effects on proportion survived from birth until 3 weeks. These correlations were not significant in the Yorkshire breed. The results show that selection for number born in total alone will lead to a deterioration in the maternal ability of sows. Selection for pre-weaning survival could be achieved by selecting on direct and maternal components jointly.

A genetic study was carried out to: (1) conduct a genetic analysis of longevity of Swedish Yorkshire sows, (2) study the environmental and genetic factors that influence the presence and severity of osteochondrosis, and (3) investigate the relationship between breeding values for osteochondrosis and longevity of sows. The data for the longevity analyses were extracted from the Swedish litter-recording scheme data bank (Quality Genetics, former Scan Avel HB). After editing original data, records of 9814 Yorkshire sows with 7553 (77%) uncensored and 2261 (23%) censored born 1986 through 1997 were used in the analyses. Litter size at first and last farrowing, age at first farrowing, backfat thickness, daily gain and weight at completion of performance test (~170 days) were included as fixed effects in all analyses. The combination of herd-year effect was treated as fixed or random, time-independent or time-dependent in different analyses. Sire effect was considered as the source of genetic variation and thus a sire model was used. The analyses of osteochondrosis were based on information on 14 388 Landrace and 14 458 Yorkshire pigs from the Swedish pig progeny-testing scheme, recorded from 1987 through 1997. The birth herd and the combination of sex, testing station, year and month for start of test were included as fixed effects in the statistical model. Variance and covariance components for osteochondrosis recorded at elbow and knee joints were estimated in a bivariate animal model by the restricted maximum likelihood method within each breed. In the survival analyses (Yorkshire sows), the fixed effects of herd-year (when it was treated as fixed effect), litter size at first and at last farrowing, age at first farrowing, backfat and gain at completion of performance test were highly significant (P < 0·01). Herd-year combination was the major cause of variation for risk of culling, compared with other fixed effects. The risk of being culled at a certain time decreased as the litter size at first and at last farrowing, or backfat of the gilt at completion of performance test increased. With increasing age at first farrowing, the risk of being culled at a certain time increased. Heritability in the original scale for longevity ranged from 0·21 to 0·31. The results for osteochondrosis showed that the combined effect of sex-testing station-year and month of start of test was highly significant (P < 0·01). Estimates of heritabilities for osteochondrosis score were similar for both Landrace and Yorkshire breeds and was, on average, 0·21. The correlations between breeding values for longevity and osteochondrosis were low (on average 0·07, adjusted for genetic trends) but were significant (P < 0·01) and in a favourable direction: higher osteochondrosis load associated with higher risk of being culled.

A 2 x 2 factorial experiment was designed in order to study the effects of feeding level during rearing and of mating policy on the reproductive performance and food intake of first- and second-litter sows. Gilts were offered food during rearing either ad libitum (AL) or at 0·8 of the AL level (R) and served either at first (E1) or third (E3) detected oestrus. A total of 160 out of the 243 animals that started the experiment were culled by the end of the second lactation, with significantly more R than AL animals (71 and 60%, respectively). During the first pregnancy, the R sows gained more live weight (LW) and backfat thickness (BF) than their AL contemporaries (+5 kg and +1.2 mm, respectively) and lost less BF during the first lactation (1.2 mm less). At weaning, no difference remained in LW or BF between AL and R sows (174 kg LW on average). The E3 females gained less LW during both pregnancies compared with those on the E1 treatment, but they remained heavier until the second weaning (208 kg, on average). During the first lactation, R consumed more food during the weeks 2 and 3 (by 0·5 kg/day, on average) than those reared previously on the AL regime, and no difference was observed between E3 and E1 females. No difference in food consumption was noted during parity two. However, when measured over the first two parities, lean animals consumed more food than fat animals. The size and the weight of the litter at birth or at weaning were not influenced by the treatment prior to service. The weaning-to-oestrus interval was longer during parity one than during parity two (5·7 and 5·0 days, respectively; P < 0·01) but it was not affected by feeding or mating treatment.

The birth weight of the piglet has an important influence on many aspects of later performance. There are, for example, relations between birth weight and growth rate as well as between birth weight and litter traits at farrowing (Rydhmer, Eliasson, Stern, Andersson and Einarsson, 1989). In a shorter perspective, birth weight affects piglet survival during the first weeks of life.

High Utter size (number born) is a common breeding goal. Piglet weight is related to the number of piglets in the Utter. Piglet weight is also related to survival; thus mortality increases with litter size.

The aim of this work was to study variation in piglet weight, some factors that may influence piglet weight and relations between litter size, piglet weight and piglet survival.

Individual piglet weights were registered in 747 litters from an experimental farm. Of the 8134 piglets born, 2326 were Swedish Yorkshire, 239 Swedish Landrace, and the rest were crosses between these two breeds. One-third of the piglets were born in gilt litters. The piglets were creep fed from the 2nd week and weaned at 6 weeks of age. They were individually weighed at birth and at 3, 6 and 9 weeks of age. Birth weight in this report refers to the weight of all piglets born, including those stillborn.