The effect of environmental enrichment on behaviour, production parameters and meat quality of finishing lambs in a feedlot

Thesis (MScAgric)--Stellenbosch University, 2017.ENGLISH ABSTRACT: The effect of environmental enrichment in the form of a wooden platform on the production parameters, social, maintenance and feeding behaviour, frequency of stereotypical behaviours and meat quality of Merino lambs in an indoor feedlot was assessed. In the first study, the effect of the wooden platform on weight gain, maintenance behaviour, social interactions and stereotypical behaviours was assessed. Two lambs were infected with footrot (infectious pododermatitis) prior to arrival at the feedlot and the effect of this disease on production parameters and behaviour was also included in the analyses. Lambs infected with footrot had the same final weight as healthy lambs, although they gained weight at a slower rate (y=1.27x+34.33 of infected lambs (n=13) versus y=2.06x+34.24 of healthy lambs (n=34)). This study found no differences in maintenance or stereotypical behaviours between lambs in treatment pens and lambs in control pens. Lambs in treatment pens did, however display a higher frequency of affiliative interactions of which the frequency increased over the fattening period. When correlations within the treatment pens were assessed, there was a significant positive correlation between affiliative interactions and the use of the platform and a significant negative correlation between the use of the platform and aggressive interactions. During the second study, the effect of the wooden platform on production parameters (ADG and FCR), social interactions, stereotypical and feeding behaviours as well as physical meat quality indicators was assessed. In this study the lambs were housed in an indoor feedlot of which one side had large open windows. It became clear that these windows also had an impact on the welfare of animals and was thus included in the analyses. Lambs in treatment that were in treatment groups on the open side of the shed showed the highest ADG and the most desirable FCR, while lambs in control pens on the open side performed intermediately and lambs on the closed side (both control and treatment pens) had the least desirable FCR and lowest ADG. The wooden platform had no effect on the meat quality, however, lambs on the open side of the pen side had heavier carcasses, lower initial pH, more back fat and a higher drip loss percentage. Lambs in control pens showed higher frequencies of stereotypical behaviours and less affiliative interactions. These lambs also had a lower frequency of feeding bouts than lambs in treatment groups, however, there were no differences in dry matter intake between the groups. All lambs fed more during the morning than in the afternoons and the feeding bouts as well as time spent feeding declined over the fattening period. However, once again there were no differences in feed intake over the fattening period and lambs most likely fed more during the night when temperatures were lower. Differences in temperaments and individual personalities of lambs most likely have a very large effect on whether or not the wooden platform will serve to improve animal welfare. Although the indicators measured did not prove the wooden platform to be overwhelmingly successful as a method of improving animal welfare, it had no detrimental effects on the lambs and it could be optimised to serve as an economical form of environmental enrichment in lamb feedlots.AFRIKAANS OPSOMMING: Die effek van omgewings verryking in die vorm van ‘n hout platform op die produksie parameters, sosiale, onderhouds en voedings gedrag, frekwensie van stereotipiese gedrag en vleis kwaliteit van Merino lammers in ‘n binnenshuise voerkraal was geanaliseer. Gedurende die eerste studie is die effek van die hout platform op gewigs toename, onderhouds gedrag, sosiale interaksies en stereotipiese gedrag geanaliseer. Met die aankoms by die voerkraal was twee lammers reeds geïnfekteer met ‘n aansteeklike vorm van vrotpootjie (infectious pododermatitis) en die effek van hierdie siekte op produksie en gedrag is toe ingelsuit by die analise. Lammer wat geïnfekteer was met vrotpootjie het dieselfde finale gewig gehad as gesonde lammers, alhoewel die gesonde lammers gewig opgetel het teen ‘n hoër tempo as siek lammers (y=1.27x+34 versus y=2.06x+34.24 van gesonde lammers). Die studie het geen verskille gekry in die onderhouds of stereotipiese gedrag tussen lammer in kontrole kampe en behandelings kampe nie. Lammer in behandelings kampe het wel ‘n hoër frekwensie van “affiliative” interaksies getoon. Hierdie frekwensie het ook toegeneem oor die periode in die voerkraal. Daar was ‘n positiewe korrelasie tussen “affiliative” interaksies en die gebruik van die hout platform en ‘n negatiewe korrelasie tussen die gebruik van die platform en aggressiewe interaksies. In die tweede studie is die effek van die hout platform op produksie parameters (gemiddelde daaglikse toename en voeromset verhouding), sosiale interaksies, stereotipiese en voedings gedrag asook fisiese vleis kwaliteit indikators geanaliseer. Tydens hierdie studie was die lammers gehuisves in ‘n skuur waarvan die een kant groot, oop vensters gehad het. Dit het duidelik geword dat hierdie vensters ook ‘n vorm van omgewings verryking bied en die effek hiervan is ingesluit in die analise. Lammers in die behandelings groepe aan die oop kant van die skuur het die hoogste gemiddelde daaglikse toename getoon sowel as die mees gewensde voeromset verhouding, terwyl lammers in kontrole groepe aan die oop kant intermediêre resultate gelewer het en die lammers aan die toe kant van die skuur (beide die in kontrole en behandelings kampe) die laagste gemiddelde daaglikse toename en die hoogste voeromset verhouding gehad het. Die houtplatform het geen effek gehad op vleis kwaliteit nie, maar lammers aan die oop kant van die skuur het wel swaarder karkasse, laar aanvanklike pH, meer vet op die kruis en ‘n hoër vog verlies persentasie gehad. Lammers in die kontrole groepe het ‘n hoër frekwensie van stereotipiese gedrag en minder “affiliative” interaksies getoon. Hierdie lammers het ook minder gegaan na die voerbakke en minder tyd spandeer aan voeding. Daar was egter geen verskille tussen die innames van die onderskeie groepe nie. Al die lammers het meer gevoed in die oggend teenoor die middag en die voedings het afgeneem oor tyd. Daar was egter nie verskille in die daaglikse voerinname nie en lammers het waarskynlik meer in die nag gevoed wanneer temperature laer was. Verskille in temperamente en individuele se persoonlikhede het waarskynlik ‘n baie groot effek op die effektiwiteit van die hout platform as ‘n vorm van omgewings verryking. Alhoewel die analises nie oorweldigende bewyse gelewer het dat die hout platform wel lammers se welsyn kan verbeter nie, het dit geen nadelige uittwerkings gehad op die lammers nie en kan dit tog geoptimiseer word om te dien as ‘n ekonomiese vorm van omgewings verryking in lammer voerkrale