Effects of socialising piglets on sow and piglet performance and behaviour of entire male piglets.

Entire male pigs show more aggressive behaviour and mounting than female pigs. By sorting growing pigs into male and female pens, at least half of the pigs are protected from the aggressive behaviour and mounting of the entire males. Mixing of unknown pigs provokes them to perform such behaviours which increase the risk for injuries. The idea behind socialising piglets is to create groups of piglets from several litters that become familiar with each other and thus show less aggressive behaviour and mounting later, when housed together after weaning. The effect of socialising piglets on animal welfare was studied on 24 sows and their 235 piglets. Male piglets were not castrated. Sows were housed in individual farrowing pens without crates. A small door was opened between two adjacent pens at a piglet age of two weeks for half of the litters (12 litters), and the other half was regarded as a control (12 litters). At weaning, control piglets were kept in groups of eight litter mates whereas socialised piglets were kept in groups of either eight entire males or eight females from two litters. Sow weight, body condition and health were recorded together with nursing events and social behaviour of piglets (aggressive, mounting, contact). There was no effect of socialisation on udder lesions or sows' relative change in body reserves. Socialised and control piglets did not differ in daily weight gain before weaning, but socialised piglets tended to have higher growth rate during the week after weaning (P = 0.07). The day after opening between pens, skin lesions were more common among socialised piglets (as compared to control piglets at the same age, P = 0.02) but at weaning, skin lesions were more common among control piglets than socialised piglets (P = 0.01). Almost all lesions were mild. No aggressive behaviour of sows towards piglets was observed. No difference between control and socialised piglets in social behaviour was seen before weaning. The frequency of aggressive and mounting behaviours was low after weaning for both socialised and control piglets, but socialised piglets showed more contact behaviour (P = 0.02). Socialised entire males showed as little aggressive and mounting behaviour as females. Nursing frequency was not affected by piglet socialisation and cross-suckling was rare. Based on the performance of piglets and sows, nursing frequency, and health of piglets and sows, we conclude that socialising entire male piglets (and their sisters) improve piglet welfare without any negative effect on the sows.

Carbon footprint based on lifetime productivity for future cows selected for resilience to climate-related disturbances.

Droughts, which can affect feed production, are projected to become more common under future climate conditions. In light of this, breeding cattle resilient to changes in feeding regimens is increasingly becoming an important topic. Body reserves can play a crucial role when feed resources are limited. We simulated populations of dairy cows selected with 2 different breeding goals: one reflecting the current breeding goal and the other placing weight on minimum level of body reserves in early lactation and change in body reserves during lactation. We considered this latter as a breeding goal for resilience. We used the 2 dynamic simulation programs ADAM and AQAL to predict performance of the cows after selection. In AQAL, we modeled moderate and severe drought by decreasing feed quality and quantity offered to cows during one year. We compared cows selected with the 2 breeding goals under 3 environments: without disturbances related to climate and with moderate and severe drought. In the environments without disturbances and the moderate drought, the cows selected with the current breeding goal had higher lifetime lactation efficiency (energy invested in milk/energy acquired from feed) and lower carbon footprint per kilogram of protein in milk and meat than cows selected for resilience. However, with severe drought, cows selected for resilience had higher lifetime lactation efficiency and lower carbon footprint per kilogram of protein in milk and meat than those selected with the current breeding goal. This suggests that cows selected for high productive performance do not perform well under very limiting conditions, leading to increased climate impact. The importance of inclusion of body reserves as a resilience trait in dairy cattle breeding depends on the future environment in which the cows will be used.

Dairy cattle farmers' preferences for different breeding tools.

Breeding technologies play a significant role in improving dairy cattle production. Scientifically proven tools for improved management and genetic gain in dairy herds, such as sexed semen, beef semen, genomic testing, dairy crossbreeding, and multiple ovulation embryo transfer (MOET), are readily available to dairy farmers. However, despite good accessibility, decreasing costs, and continuous development of these tools, their use in Sweden is limited. This study investigated Swedish dairy farmers' preferences for breeding tools through a survey including a discrete choice experiment. The survey was distributed online to 1 521 Swedish farmers and by an open link published through a farming magazine. In total, the study included 204 completed responses. The discrete choice experiment consisted of 10 questions with two alternative combinations, which gave 48 combinations in total. Utility values and part-worth values were computed using a conditional logit model based on the responses in the discrete choice experiment for nine groups of respondents: one group with all respondents, two groups based on respondents using dairy crossbreeding or not within the past 12 months, two based on herd size, two based on respondent age, and two based on whether respondents had used breeding advisory services or not. The strongest preferences in all groups were for using sexed semen and beef semen. Genomic testing was also significantly preferred by all groups of respondents. Except in large herds, MOET on own animals was significantly and relatively strongly disfavoured by all groups. Buying embryos had no significant utility value to any group. Dairy crossbreeding had low and insignificant utility values in the group of all respondents, but it was strongly favoured by the group that had used dairy crossbreeding within the past 12 months, and it was disfavoured by the group that had not. Part-worth values of combined breeding tools showed that combinations of sexed and beef semen, alone or with genomic testing without dairy crossbreeding, were the most preferred tools. Compared with the most common combinations of breeding tools used in the past 12 months, the part-worth values indicated that Swedish dairy farmers may prefer to use breeding tools more than they do today. Statements on the different breeding tools indicated that the respondents agreed with the benefits attributed to the breeding tools, but these benefits may not be worth the cost of genomic testing and the time consumption of MOET. These valuable insights can be used for further development of breeding tools.

Genetic consequences of terminal crossbreeding, genomic test, sexed semen, and beef semen in dairy herds.

The development of breeding tools, such as genomic selection and sexed semen, has progressed rapidly in dairy cattle breeding during the past decades. In combination with beef semen, these tools are adopted increasingly at herd level. Dairy crossbreeding is emerging, but the economic and genetic consequences of combining it with the other breeding tools are relatively unknown. We investigated 5 different sexed semen schemes where 0, 50, and 90% of the heifers; 50% of the heifers + 25% of the first-parity cows; and 90% of the heifers + 45% of the first-parity cows were bred to sexed semen. The 5 schemes were combined in scenarios managing pure-breeding or terminal crossbreeding, including genomic testing of all newborn heifers or no testing, and keeping Swedish Red or Swedish Holstein as an initial breed. Thus, 40 scenarios were simulated, combining 2 stochastic simulation models: SimHerd Crossbred (operational returns) and ADAM (genetic returns). The sum of operational and genetic returns equaled the total economic return. Beef semen was used in all scenarios to limit the surplus of replacement heifers. Terminal crossbreeding implied having a nucleus of purebred females, where some were inseminated with semen of the opposite breed. The F1 crossbred females were inseminated with beef semen. The reproductive performance played a role in improving the benefit of any of the tools. The most considerable total economic returns were achieved when all 4 breeding tools were combined. For Swedish Holstein, the highest total economic return compared with a pure-breeding scenario, without sexed semen and genomic test, was achieved when 90% sexed semen was used in heifers and 45% sexed semen was used for first-parity cows combined with genomic test and crossbreeding (+€58, 33% crossbreds in the herd). The highest total economic return for Swedish Red compared with a pure-breeding scenario, without sexed semen and genomic test, was achieved when 90% sexed semen was used in heifers combined with genomic test and crossbreeding (+€94, 46% crossbreds in the herd). Terminal crossbreeding resulted in lower genetic returns across the herd compared with the corresponding pure-breeding scenarios but was compensated by a higher operational return.

Economic consequences of dairy crossbreeding in conventional and organic herds in Sweden.

This study simulated the consequences of crossbreeding between Swedish Holstein and Swedish Red on herd dynamics and herd profitability under Swedish conditions. Two base herds were simulated using a stochastic herd simulation model, SimHerd Crossbred. The herds reflected average Swedish conventional and organic herds having purebred Swedish Holstein. For each base herd, 3 breeding strategies were simulated: pure-breeding, 2-breed terminal crossbreeding, and 2-breed rotational crossbreeding. The terminal crossbreeding strategy implied having a nucleus of Swedish Holstein and a proportion of F1 Swedish Red × Swedish Holstein crossbred cows within the same herd. The crossbreds in this herd did not produce replacement heifers but exclusively beef × dairy cross calves. Beef semen was also used in the pure-breeding (10-20% in cows) and the rotational crossbreeding (40% in cows) strategies to retain a limited surplus of replacement heifers. To ensure an adequate number of crossbreds in the terminal crossbreeding strategy, X-sorted sexed semen was used for insemination in all the purebred heifers. The outcome was 67% purebred and 31% F1 crossbreds in the herd. In addition, 31% heterosis was expressed compared with 67% heterosis expressed using a 2-breed rotational crossbreeding strategy. Compared with the pure-breeding strategy, crossbreeding increased the annual contribution margin per cow by €20 to €59, with the rotational crossbreeding strategy creating the largest profitability. The increased profitability was mainly due to improved functional traits, especially fertility. For the conventional production system, the replacement rate was 39.3% in the pure-breeding strategy and decreased to 35.8 and 30.1% in the terminal and rotational crossbreeding strategy, respectively. Similar changes happened in the organic production system. Additionally, the crossbreeding strategies earned €22 to €42 more annually per cow from selling live calves for slaughter due to the extended use of beef semen. Milk production was similar between pure-breeding and terminal crossbreeding, and only decreased 1 to 2% in rotational crossbreeding. These results show that crossbreeding between Swedish Holstein and Swedish Red can be profitable in both conventional and organic Swedish herds using the strategies we have simulated. However, some aspects remain to be investigated, such as the economically optimal breeding strategy, genetic improvement, and transition strategies.

Simulating consequences of choosing a breeding goal for organic dairy production.

In Denmark, Finland, and Sweden, the Nordic Total Merit index is used as the breeding selection tool for both organic and conventional dairy farmers based on common economic models for conventional dairy farming. Organic farming is based on the principles of organic agriculture (POA) defined by the International Federation of Organic Agriculture Movements. These principles are not set up with an economic point of view, and therefore it may be questionable to use a breeding goal (BG) for organic dairy production based on economic models. In addition to economics and the principles of organic agriculture, it is important to look at farmers' preferences for improving BG traits when setting up a BG for organic farming. The aim of this research was to set up, simulate, and compare long-term effects of different BG for organic and conventional dairy production systems based on economic models, farmers' preferences, and POA, with particular emphasis on disease resistance or on roughage consumption and feed efficiency. The BG based on economic models and on farmers' preferences were taken from previous studies. The other BG were desired gains indices, set up by means of a questionnaire about relatedness between the POA and BG traits. Each BG was simulated in the stochastic simulation program ADAM. The BG based on POA, with particular emphasis on disease resistance or on roughage consumption and feed efficiency, caused favorable genetic gain in all 12 traits included in this study compared with 6 traits for the other BG. The BG based on POA, with particular emphasis on disease resistance or on roughage consumption and feed efficiency, were very different from BG for organic and conventional production based on economic models and farmers' preferences in both simulated genetic change and correlations between BG. The BG that was created based on the principles of organic agriculture could be used as a specific index for organic dairy farming in Denmark, but this index was economically not very sustainable. Hence, an intermediate breeding goal could be developed by breeding companies to address both economics and the principles of organic agriculture.

Invited review: Breeding and ethical perspectives on genetically modified and genome edited cattle.

The hot topic of genetic modification and genome editing is sometimes presented as a rapid solution to various problems in the field of animal breeding and genetics. These technologies hold potential for future use in agriculture but we need to be aware of difficulties in large-scale application and integration in breeding schemes. In this review, we discuss applications of both classical genetic modifications (GM) using vectors and genome editing in dairy cattle breeding. We use an interdisciplinary approach considering both ethical and animal breeding perspectives. Decisions on how to make use of these techniques need to be made based not only on what is possible, but on what is reasonable to do. Principles of animal integrity, naturalness, risk perception, and animal welfare issues are examples of ethically relevant factors to consider. These factors also influence public perception and decisions about regulations by authorities. We need to acknowledge that we lack complete understanding of the genetic background of complex traits. It may be difficult, therefore, to predict the full effect of certain modifications in large-scale breeding programs. We present 2 potential applications: genome editing to dispense with dehorning, and insertion of human genes in bovine genomes to improve udder health as an example of classical GM. Both of these cases could be seen as beneficial for animal welfare but they differ in other aspects. In the former case, a genetic variant already present within the species is introduced, whereas in the latter case, transgenic animals are generated-this difference may influence how society regards the applications. We underline that the use of GM, as well as genome editing, of farm animals such as cattle is not independent of the context, and should be considered as part of an entire process, including, for example, the assisted reproduction technology that needs to be used. We propose that breeding organizations and breeding companies should take an active role in ethical discussions about the use of these techniques and thereby signal to society that these questions are being responsibly addressed.

Risk aversion affects economic values of blue fox breeding scheme.

The profit and production of an average Finnish blue fox farm was simulated using a deterministic bio-economic farm model. Risk was included using Arrow-Prat absolute risk aversion coefficient and profit variance. Risk-rated economic values were calculated for pregnancy rate, litter loss, litter size, pelt size, pelt quality, pelt colour clarity, feed efficiency and eye infection. With high absolute risk aversion, economic values were lower than with low absolute risk aversion. Economic values were highest for litter loss (18.16 and 26.42 EUR), litter size (13.27 and 19.40 EUR), pregnancy (11.99 and 18.39 EUR) and eye infection (12.39 and 13.81 EUR). Sensitivity analysis showed that selection pressure for improved eye health depended strongly on proportion of culled animals among infected animals and much less on the proportion of infected animals. The economic value of feed efficiency was lower than expected (6.06 and 8.03 EUR). However, it was almost the same magnitude as pelt quality (7.30 and 7.30 EUR) and higher than the economic value of pelt size (3.37 and 5.26 EUR). Risk factors should be considered in blue fox breeding scheme because they change the relative importance of traits.

Breakeven prices for recording of indicator traits to reduce the environmental impact of milk production.

A breeding scheme using genomic selection and an indicator trait for environmental impact (EI) was studied to find the most effective recording strategy in terms of annual monetary genetic gain and breakeven price for the recording of indicator traits. The breakeven price shows the investment space for developing a recording system for an indicator trait. The breeding goal consisted of three traits ­ milk production, functional trait and environmental impact ­ with economic values of €83, €82 and €-83, respectively. The first scenario included only breeding goal traits and no indicator traits (NoIT). The other scenarios included all three breeding goal traits and one indicator trait (IT) for EI. The indicator traits were recorded on a large scale (stayability after first lactation and stature), medium scale (live weight and greenhouse gases (GHG) measured in the breath of the cow during milking) or small scale (residual feed intake and total enteric methane measured in a respiration chamber). In the scenario with stayability, the genetic gain in EI was over 11% higher than it was in NoIT. The breakeven price of recording stayability was €8 per record. Stayability is easy to record in the national milk recording system, and its use as an indicator trait for EI would not generate any additional recording costs. Therefore, stayability would be a good indicator trait to use to mitigate EI. The highest genetic gain in EI (23% higher compared to NoIT) was achieved when the GHG measured in the breath of the cow was used as indicator trait. The breakeven price for this indicator trait was €29 per record in the reference population. Ideally the recording of a specific indicator trait for EI would take place when: (i) the genetic correlation between the IT and EI is high; and (ii) the number of phenotypic records for the indicator trait is high enough to achieve a moderately high reliability of direct genomic values.

Evaluation of the sustainability of contrasted pig farming systems: the procedure, the evaluated systems and the evaluation tools.

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.

Evaluation of the sustainability of contrasted pig farming systems: integrated evaluation.

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.

Evaluation of the sustainability of contrasted pig farming systems: breeding programmes.

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.

Inverted teats (Mammillae invertitae) in gilts - effect on piglet survival and growth rate.

In the modern pig industry, the increasing number of piglets born per litter augments the importance of the number of functional teats in the sow. The aim of this study was to evaluate the function and importance of inverted teats during nursing and to analyze structural and functional differences between the mammary glands of inverted teats versus normal teats. Nine farrowing gilts (8 purebred Swedish Yorkshire gilts and 1 cross between Swedish Yorkshire and Norwegian Landrace) and 94 piglets (59 piglets suckling normal teats, 32 piglets suckling protruded teats [i.e., previously inverted], 2 piglets suckling inverted teats, and 3 piglets suckling considerably smaller teats) were included in the study. Teat fidelity (keeping the same teat between the nursings) was registered, excluding the first 48 h postpartum. Piglet weight was recorded daily during the first week of life and thereafter once a week until weaning at 4 wk of age. Weight and growth rate were analyzed using repeated observation mixed-model analysis of variance. The 2 piglets that suckled the inverted teats were not able to emerge the teats and they were euthanized 4 and 8 d after birth, respectively, due to loss of BW. The average weight at weaning (28 d of age) was 8.1 kg (range 3.2-13.8 kg). In the normal teats (n = 53), the weight of the corresponding mammary gland tissue at necropsy was positively correlated to the piglet average daily weight gain during wk 2 (r = 0.33, P < 0.05), 3 (r = 0.55, P < 0.001), and 4 (r = 0.47, P < 0.001). In the protruded teats (n = 32), the weight of the corresponding mammary gland tissue was positively correlated to the piglet average daily weight gain during wk 2 (r = 0.63, P < 0.001) and 3 (r = 0.43, P < 0.05). Among the piglets nursing normal teats, 82% kept fidelity to its teat and the corresponding percent for the protruded teats was 26%. In 7 of the 9 sows, the weaning weight of the piglets suckling protruded teats was numerically lower compared to the piglets suckling normal teats, although the difference was not statistically significant. Piglets nursing small teats had lower weaning weight (4.8 kg) and the corresponding mammary tissue also had lower weight (335 g). This study indicates the importance of an adequate number of well-developed and well-functioning teats in healthy sows for the growth and development of the piglets but also emphasizes the complexity of the interaction between the nursing sow and her piglets.

Genetic parameters for feed intake, litter weight, body condition and rebreeding success in primiparous Norwegian Landrace sows.

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.

Genomic selection using indicator traits to reduce the environmental impact of milk production.

The aim of this simulation study was to test the hypothesis that phenotype information of specific indicator traits of environmental importance recorded on a small-scale can be implemented in breeding schemes with genomic selection to reduce the environmental impact of milk production. A stochastic simulation was undertaken to test alternative breeding strategies. The breeding goal consisted of milk production, a functional trait, and environmental impact (EI). The indicator traits (IT) for EI were categorized as large-, medium-, or small-scale, depending on how the traits were recorded. The large-scale traits were stayability and stature; the medium-scale traits were live weight and methane in the breath of the cow measured during milking; and the small-scale traits were residual feed intake and methane recorded in a respiration chamber. Simulated scenarios considered information for just one IT in addition to information for milk production and functional traits. The annual monetary genetic gain was highest in the large-scale scenario that included stayability as IT. The annual monetary gain in the scenarios with medium- or small-scale IT varied from €50.5 to 47.5. The genetic gain improvement in EI was, however, best in the scenarios where the genetic correlation between IT and EI was ≥0.30 and the accuracy of direct genomic value was ≥0.40. The genetic gain in EI was 26 to 34% higher when indicator traits such as greenhouse gases in the breath of the cow and methane recorded in respiration chamber were used compared with a scenario where no indicator trait was included. It is possible to achieve increased genetic gain in EI by using a highly correlated indicator trait, but it requires that the established reference population for the indicator trait is large enough so that the accuracy of direct genomic values will be reasonably high.

Welfare of entire male pigs is improved by socialising piglets and keeping intact groups until slaughter.

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.

Genetic associations between behavioral traits and direct-social effects of growth rate in pigs.

This study examined the behavioral consequences of selecting pigs using a social genetic model for growth. Calculations enable each member of a group of pigs to be given a direct breeding value (DBV) and a social breeding value (SBV), which can be summarized into a total breeding value (TBV) for growth. Selection for growth TBV could affect animal behavior because social effects account for within-group interactions. Data were recorded from 96 groups of Yorkshire and Yorkshire × Landrace pigs in a nucleus herd. Each group contained 15 pigs fed ad libitum from 2 feeders; the space allowance was 0.85 m2/pig. Average daily gain was quantified from 35 to 100 kg of BW. Fighting and bullying activity at mixing (period 1), lying frequency 3 wk after mixing (period 2), and counts of skin lesions in periods 1 and 2 were recorded. The DBV for these traits were estimated with a classic animal model. We simulated different correlations between the direct genetic effect and the social genetic effect on growth rate (r(DS)), 2 components that respectively determine a pig's genetic capacity to grow and its genetic influence on growth of group mates: r(DS) was successively assumed to be 0 and ±0.12, ±0.20, ±0.29, and ±0.58. Finally, the correlations between DBV, SBV, and TBV for ADG, as well as the DBV for behavior and skin lesions, were calculated and tested for a level of significance at P < 0.05. The gradient from negative to positive values of r(DS) refers to a progressive path running from genetic antagonism to genetic mutualism for growth. If rDS in the population truly ranged between -0.58 and -0.20, correlations for TBV for ADG with DBV for fighting and bullying progressively increased with rDS. Consequently, if rDS was low (between -0.12 and +0.12) or positive (>+0.12), pigs with high TBV for ADG had higher DBV for bullying other pigs in the group and for fighting than pigs with lower TBV for ADG. Pigs with high TBV for ADG did not differ from other pigs in their DBV for lesions to the anterior part of the body, but they had a lower DBV for posterior lesions, whereas in period 2, they had higher DBV for posterior lesions and lower DBV for lying. Under genetic mutualism for growth and in housing conditions similar to those in the present study, selection for growth TBV would promote the rapid establishment of the dominance relationships, with more aggressive contests among group mates at mixing. Pigs would subsequently be more active but, judging by skin lesions, less willing to fight in a more stable social situation.

Heritability of shoulder ulcers and genetic correlations with mean piglet weight and sow body condition.

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).

There is room for selection in a small local pig breed when using optimum contribution selection: a simulation study.

Selection progress must be carefully balanced against the conservation of genetic variation in small populations of local breeds. Well-defined breeding programs with specified selection traits are rare in local pig breeds. Given the small population size, the focus is often on the management of genetic diversity. However, in local breeds, optimum contribution selection can be applied to control the rate of inbreeding and to avoid reduced performance in traits with high market value. The aim of this study was to assess the extent to which a breeding program aiming for improved product quality in a small local breed would be feasible. We used stochastic simulations to compare 25 scenarios. The scenarios differed in size of population, selection intensity of boars, type of selection (random selection, truncation selection based on BLUP breeding values, or optimum contribution selection based on BLUP breeding values), and heritability of the selection trait. It was assumed that the local breed is used in an extensive system for a high-meat-quality market. The simulations showed that in the smallest population (300 female reproducers), inbreeding increased by 0.8% when selection was performed at random. With optimum contribution selection, genetic progress can be achieved that is almost as great as that with truncation selection based on BLUP breeding values (0.2 to 0.5 vs. 0.3 to 0.5 genetic SD, P < 0.05), but at a considerably decreased rate of inbreeding (0.7 to 1.2 vs. 2.3 to 5.7%, P < 0.01). This confirmation of the potential utilization of OCS even in small populations is important in the context of sustainable management and the use of animal genetic resources.

Selection of bull dams for production and functional traits in an open nucleus herd.

The aim of this study was to compare different scenarios for bull dam selection in a nucleus herd. A deterministic simulation study using selection index methodology was undertaken. In the scenarios studied, differing amounts of information on functional traits were available when bull dams were selected, and the resulting genetic responses in these traits were compared. Field-recorded fertility traits used in the scenarios were available as progeny test results of artificial insemination bulls: these included pregnant at first insemination (PFI), interval between calving and first insemination (CFI), and cases of reproductive disorders (RD). Similarly, field-recorded cases of clinical mastitis (CM), lactation somatic cell score (LSCS), and protein yield (PY) were included for pedigree selection. In the scenarios, heat intensity score and progesterone levels were treated as new indicator traits of fertility recorded in the nucleus herd. Traits CFI and LSCS were assumed to be better recorded with higher heritability in the nucleus herd than in ordinary herds. Economic weights currently used in Nordic Cattle Genetic Evaluation (NAV) were adapted and used in the scenarios. The results showed that these weights, if used in multiple trait genetic evaluation, would lead to undesirable genetic changes in functional traits for the bull dam selection path in a nucleus environment. More frequent recording of additional traits failed to improve selection for functional traits, as did more frequent recording of ordinary traits. Restriction index methodology was used to derive the bull dam total weights that gave no unfavorable response (i.e., zero genetic change) in traits PFI, CFI, and CM. When summarized over lactations, the new bull dam total weights, when additional records from nucleus were used, had to be 12 to 23 times higher for fertility, and 3 times higher for mastitis, than the presently used NAV weights, if these traits were to remain unchanged through the bull dam selection path. Thus, nucleus herd selection of bull dams is questionable for low heritability traits that are already recorded in the field.