The maternal behaviour of the pig in the farrowing crate
Appleyard, Stephen John
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One of the main objectives of this thesis was to move towards an understanding of what constitutes adaptive, good maternal behaviour (Chapter 1). The wider goal of this research is the development of sows with improved maternal characteristics through selective breeding. To this end, it was necessary to quantify and describe stable behavioural traits that have functional consequences in terms of the survival of piglets. The easiest way of doing this was to look for correlations between sow maternal behaviour and piglet mortality, and infer that good maternal behaviour is not doing these behaviours.The majority of sows in this, and many other countries, give birth in the farrowing crate (Chapter 1). The farrowing crate was designed to reduce the impact of careless lying behaviour on piglet crushing, however, it still suffers from a high piglet mortality rate (Chapter 1). It was not known whether the improvement of sow maternal behaviour would alter the number of piglet mortalities in the crate system. This thesis has indicated that stable behavioural traits of the sow do influence the number of piglet mortalities in the farrowing crate. The results contained in this thesis suggest that it might be possible to reduce the incidence of crushing by not breeding from sows that frequently stand up and lay back down again in the crate. Further research is necessary to assess whether these behavioural traits are heritable.Importantly, the thesis has also identified that the behavioural strategy of looking out for piglets, and moving them aside if necessary, is an aspect of good maternal behaviour that does not reduce crushing in the crate. Therefore, the cost of using a system designed to limit the impact of poor maternal behaviour is that the impact of good maternal behaviour is also limited. Consequently, sows that adopt the strategy of frequent but careful posture changing are likely to have more piglet mortalities in the crate system than what they would do if they were in a farrowing pen.This thesis has also showed that it is possible to identify the maternal type of a sow before parturition starts. Thus, savaging gilts were identified from their nesting behaviour, whilst a low responsiveness towards piglets (a stable behavioural trait) was associated with sows that were difficult to move into the crate. The identification of gilts with good maternal behaviour would be most useful prior to service. Therefore, further work would need to focus on behavioural tests that can be performed prior to service and which correlate with the stable maternal traits identified here.