Influenced by changes in
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societal opinions and in technology developments
Merks, J.W.M. et al, 2012. New phenotypes for new breeding goals in pigs. Animal, 6:4, pp 535-543.
Genetic trends in pigs can be fast but it takes about 3 to 5 years for the changes to actually take place in the production herds and for the consumers to experience the benefits. Present pig breeding programs have breeding goals including traits of interest, the relative significance of these traits and the direction for improvement. The traits of interest depend of the expected market requirements of pork set by consumer’s expectations and willingness of the society too accept production methods. Therefore, a good prediction of future trends is necessary. Pork chain development combined with information technology facilitate to sample breeding goal associated phenotypes (traits) in a cost effective manner. As you can see in figure XXX the current interests of farmers, citizens, governments representing the society and food industry requires new “phenotypes”: vitality, uniformity, robustness, welfare and health and traits to reduce the carbon food print of pork production, while keeping the production efficiency and product quality.
Improving vitality will result in better survival of piglets during the prenatal period, less piglets born dead, no dead or sick pigs in suckling, nursery and finishing, less sows culled after first parity and lower sickness and mortality in older sows. Improving of uniformity at different levels in the production chain has a positive effect on the management of the animals and on the processing. Uniformity in birth weight of a litter decreases mortality especially of smaller piglets. Uniformity in protein deposition leads to more uniformity in growth and the age at the required slaughter weight and gives a more efficient utilisation of dietary protein. Uniformity in slaughter weight and carcass length increases slaughter plant efficiency. Uniformity in pork chops, meat colour, marbling and drip loss is useful for retail shelves and consumers. Increasing robustness of the animals will improve the ability of pigs to adapt to different stressors they may be face in their life: disease challenges, extremely hot or cold temperatures, low quality feed or changes in housing and management, e.g. by transition from individual to group housing. Reduction of the carbon footprint of pork production can be realised by improvements in digestive efficiency and reductions in maintenance requirements. In pork production males were castrated. Intact males sometimes produce a very bad smell that is smelled after the pork chop is fried. Castration is considered in many countries as a painful interference in the young piglets that should be avoided. But recently selection based on genetic markers opened up selection against boar taint making castration of boars no longer necessary. This is a wish in society existing already for a long period of time. Genomic selection will be of great help to select for the new “phenotypes” and the new more complex breeding goals. Automation processes for identification of animals and carcasses and recording of their traits in different parts of the production chain will result in very informative databases that provide DNA profiles and phenotypes to be used in selectionEspecially in the developed countries, societal concerns call for an improvement of health and welfare of sows and finishers. Therefore, pig breeding companies (e.g. Topigs Norsvin) extend the selection and breeding goal traits with longevity traits of sows and robustness traits of piglets. Longevity of sows is negatively influenced by the incidence of leg injuries and lameness and the incidence of uterine prolapses. These are heritable traits, e.g. the heritability for the incidence of uterine prolapses is 0.20-0.30. Robustness traits of finishers will be improved by selection for survival of piglets and finishers. Variation in daily feed intake is used as an indicator of robustness and expresses the resilience of an animal (less variation in daily feed intake = more robust and more resilience). Natural selection against the Porcine Reproductive and Respiratory Syndrome (PPRS) is under development and gene-editing is in this respect in discussion. The technique is promising in this respect, but the societal opinion is at least in the European Union negative.
The European Food Safety Authority (EFSA) express the societal concern in recommendations towards breeding companies for the welfare of pigs: to avoid excessive competition within a litter, the litter size should not exceed the number of functional teats of a sow. To improve the longevity of a sow the EFSA believes that the average number of piglets born alive should not exceed 12-14. Breeding companies should anticipate on free farrowing systems with selection on piglet weight and viability, and on maternal behaviour, good leg conformation and good udder quality of sows.
Castration of boars is or will be banned in developed countries and therefore (genomic) selection against boar taint is required. Biting behaviour is still a point of concern. Research is performed by breeding companies with video techniques to study behaviour and to find the biters and the victims.
Fortunately, the technological developments create opportunities to record new selection traits intensively and to extend the breeding goal with new traits that meet societal wishes and improves health and welfare of sows and finishers.