Behaviour and performance of growing and finishing pigs depending on different housing conditions and sire breeds
Doctoral thesis
Date of Examination:2022-08-30
Date of issue:2022-10-11
Advisor:Prof. Dr. Imke Traulsen
Referee:Prof. Dr. Imke Traulsen
Referee:Prof. Dr. Dr. Matthias Gauly
Files in this item
Name:Dissertation_Finale Pubversion.pdf
Size:1.42Mb
Format:PDF
Abstract
English
Conventional pig farmers and more particularly their pigs face many challenges throughout different production stages that can alter the welfare and health of the animals and impair the farmers economy and motivation in the long run. In Germany, all pig production stages are regulated but these regulations are seen increasingly critical by different stakeholders as they outline only minimum husbandry and management standards. On one hand, first amendments of the “Animal Welfare Livestock Husbandry Ordinance” (German: Tierschutz- Nutztierhaltungsverordnung), that for example decrease the duration of continuous confinement of lactating sows or prohibit the castration of piglets without anaesthesia, and on the other hand, the introduction of so-called animal welfare labels for livestock products, show both the willingness by government, trade and customers to improve husbandry conditions but it also increases the urge for substantiating research, as some problems like aggressive interactions at regrouping and tail-biting during rearing and finishing period are still unsolved for conventional housing practices. The objectives of this dissertation were to investigate the effects of different housing systems during suckling, rearing and finishing period and of different sire breeds on the behaviour and performance of growing and finishing pigs. In particular, the aim was to study whether loose-housing of lactating sows and their litters (single and group housing), reduced regrouping events (single-phased vs. two-phased rearing and/or fattening) or the use of traditional sire lines could improve the well-being of rearing and fattening pigs in terms of reducing skin lesions, tail lesions, tail losses, serum cortisol levels and maintain or at best increase average daily gains, especially for undocked pigs. Research Article One studied how farrowing and rearing systems affect skin lesions, serum cortisol, and aggressive behaviour as indicators for weaning stress of piglets. Therefore, 3144 piglets were weaned between May 2016 and March 2018 from three different farrowing systems: farrowing crates (FC), single-housing free-farrowing pens (FF), and group housing of lactating sows and litters (GH). After weaning and regrouping, the piglets were moved to conventional rearing pens (conv; 5.7 m2) or to so-called wean-to-finish pens (w-f; 12.4 m2). One day after weaning, the piglets’ behaviour was observed and the animals were assessed for skin lesions. One week before and one day after weaning the piglets were blood sampled in order to analyse the individual difference in serum cortisol. Significantly more piglets raised in FC and FF had moderate and severe skin lesions than piglets from GH. Also, piglets born in GH showed lower differences in serum cortisol, and fought less and for shorter durations than piglets born in FC and FF. Greater cortisol differences and significantly longer fights could be found in piglets that were weaned into w-f pens compared to piglets in conv pens. The first research study concluded, that group housing during the suckling period reduced the weaning stress for piglets with regard to skin lesions, serum cortisol, and aggressive behaviour. The greater space allowance of wean-to-finish pens showed no benefits concerning the studied parameters compared to the space allowance of conventional rearing pens. The first research article showed the potential of alternative housing systems for weaning stress, but no long-term effects were investigated, especially in regard to the housing of undocked pigs. The aim of Research Article Two was to present practicable alternatives to stressful weaning and tail-docking. Therefore, 1106 pigs were weaned from: conventional farrowing crates (FC), free-farrowing pens (FF), or group housing of lactating sows (GH) into either conventional rearing pens (Conv) or the piglets remained in their farrowing pens for rearing (Reaf). Batchwise, the tails of the pigs were docked or left undocked. For this study, all pigs were relocated and regrouped for the fattening period. Starting one day after weaning, the pigs were assessed weekly for tail lesions and losses and every two weeks during rearing period and every four weeks during fattening period for skin lesions. The average daily gain was calculated separately for the rearing and fattening period. The results showed that significantly less Conv-GH pigs had skin lesions than Conv-FC and Conv-FF pigs after weaning. After the regrouping for fattening, significantly less Reaf-GH pigs had skin lesions than Conv pigs, Reaf-FC and Reaf-FF. While the incidence of tail lesions of undocked Conv pigs reached its peak in week 4 (66.8 %), tail lesions of undocked Reaf pigs reached their maximum (36.2 %) two weeks later. At the end of fattening, almost all of the undocked Conv pigs (99.3 %) and less than half of the undocked Reaf pigs (43.1 %) endured tail loss. To conclude, the group housing of piglets during suckling period reduced the incidence of skin lesions. The incidence of tail lesions and tail losses of undocked pigs could be significantly reduced by rearing in the farrowing pen. Moreover, no housing system affected the performance negatively. As research article one and two revealed promising effects of the housing systems on the occurrence of injurious behaviour, i.e. on the incidence of skin and tail lesions and tail losses, the focus of Research Article Three was then to investigate the potential of different local, traditional sire breeds for the behaviour and performance of rearing pigs. Therefore, hybrid sows (BHZP Landrace x BHZP Large White) were paired with either Swabian-Hall (SH), Bentheim Black Pied (BB) or BHZP-Piétrain (Pi) boars. In total 1561 piglets were weaned of which tails were either left intact (43.5 %) or docked (56.5 %), and all male piglets were castrated. The piglets were housed conventionally on fully slatted plastic floors in mixed-sex groups. Starting on the first day after weaning, skin lesions were scored once and tail lesions and losses were scored weekly until the end of rearing. Also, the average daily gain was calculated for the rearing period and the activity behaviour was analysed for focus pens. The results showed that significantly fewer BB pigs had severe skin lesions on the front body than SH or Pi pigs. Moreover, significantly more BB pigs were assessed with no tail lesions and tail losses for the first four weeks of the rearing period, compared to SH and Pi pigs but these significant differences dissolve in the last four weeks of rearing. However, numerically more SH pigs were scored with moderate and severe tail losses at the end of rearing. In terms of performance, Pi pigs had significantly higher average daily gains than SH and BB pigs, whether docked or undocked. Against previous expectations, no significant effect of the sire breed or mean tail lesion score could be detected on the activity behaviour of the focus pens. In conclusion, the present dissertation could confirm that both, the housing system and the sire breed, have an effect on the behaviour and performance of growing and finishing pigs. The amount and duration of aggressive behaviour and thus the incidences of skin lesions could be decreased by reducing regrouping events at weaning through group housing during the suckling period and/or through litterwise rearing in the farrowing system, all without affecting the piglets’ expected performance. This decrease in weaning stress lowered the incidence of tail lesions and tail losses of undocked pigs significantly. Significantly fewer BB pigs had severe skin lesions compared to SH or Pi pigs. Also, significantly more BB pigs were scored without tail lesions and tail losses for the first four weeks of the rearing period. However, piglets from the two traditional sire breeds could not compete with docked and undocked Piétrain pigs in terms of performance which possibly might be compensated by an adjustment of the feeding regime.
Keywords: farrowing system; rearing system; aggressive behaviour; tail biting; local pig breed; pig welfare