| Abstract: |
This thesis explores research published between 2013-2017 and focuses on welfare issues in Italian pig production. This sector is characterized by animals (heavy pigs) slaughtered for dry-cured products at a minimum of nine months and 160 kg (compared to 110-115 kg of other EU systems). The first set of studies investigated the feasibility of avoiding tail docking under different husbandry conditions (Trial A and Trial B), besides the benefit of providing straw enrichment by racks (Trial A). Surgical tail docking within the first week of life is the routine solution in several EU countries to prevent tail biting, an abnormal behaviour causing stress, pain and tail injuries. In Trial A, tail presence did not significantly increase the risk of tail lesions, the level of acute phase proteins (i.e. blood markers of inflammation), or impair the health status (mortality, lung and gastric lesions) over the 30 weeks of fattening. Small amounts of straw (70 g/day per pig) increased the motivation for pigs to explore the environment, reduced serum haptoglobin (i.e. the inflammatory state) and reduced the risk of tail biting (at weeks 3, 9, 18) and ear biting (at weeks 3, 9). At slaughter, the straw group revealed a gastric ulcer risk ~ 70% lower than the one without straw (OR: 0.27). Males were at higher ulcer risk than females (OR: 1.52). In Trial B, tail presence had no effect on blood markers, conflicts, or ear and tail biting behaviours, both at the weaner and fattening phase. At fattening, however, undocked animals showed a higher prevalence of mild tail lesions (P<0.01) and a lower frequency of belly nosing behaviour (P<0.05). Blood samples taken from the animals in trial A and trial B were found to have a variable degree of spurious haemolysis. The release of free haemoglobin can bias the quantification of several analytes. Therefore, a further study evaluated the effect of physical haemolysis in 3 aliquots (on a scale of 1+ to 3+) of 30 non-haemolytic sera, in order to assess the threshold of acceptability for a panel of 27 blood analytes at increasing levels of haemolysis. A further issue explored was the assessment of heavy pig welfare at the time of slaughtering, in a European project which enabled the gathering of data with other Countries (Spain, Portugal, Finland, Brazil). Welfare Quality Protocol® was applied in nine Italian abattoirs, providing information for reference values of several animal-based indicators. Finally, the impact of sexual maturity in heavy female pigs was investigated, on the basis of previous studies on light pigs. They reported mounting and agonistic behaviour to affect animal welfare in both males and females, due to sexual activity. In the study, a reduction was found (P<0.05) in immunocastrated vs. entire females for aggressive interactions, haptoglobin levels, serum cortisol levels and back lesions at given timepoints throughout fattening. There was no effect on slaughter performances (back fat thickness and percentage of lean tissue). Taken together, the outcomes of all these studies highlighted the presence of specific welfare concerns in the Italian pig sector, due to the heavier final live weight (problematic during certain slaughtering phases) and the achievement of sexual maturity (leading to increased aggression of females). Similarly to other EU systems, tail biting was manageable with proper enrichment material; it occurred mostly at an early age and under poor health conditions. The studies have also brought practical implications in routine blood testing (by overcoming the unsuitability of blood measures due to haemolysis) and in investigating the role of gastric ulcers as an innovative stress marker.
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