Pecking Behavior in Conventional Layer Hybrids and Dual-Purpose Hens Throughout the Laying Period.

To avoid the killing of surplus male layer chickens, dual-purpose hybrids are suggested as an alternative approach. These strains may offer additional advantages compared to conventional laying hens, for instance, a lower tendency to develop injurious pecking behavior. The aim of this study was to assess the behavior, with focus on pecking behavior, of conventional layers (Lohmann Brown plus, LB+) and dual-purpose hens (Lohmann Dual, LD). About 1,845 hens per strain with intact beaks were housed in four stable compartments in aviary systems. Video-based scan sampling of general behaviors and continuous observations of pecking behavior were carried out between 25 and 69 weeks of life. With the exception of "dustbathing" and "scratching," hybrid × time during the laying period affected all of the observed general behaviors [F (2, 89) = 3.92-10.81, P < 0.001-0.05]. With increasing age, the LB+ hens performed more general pecking, more locomotion and less comfort and sitting behavior. General pecking and comfort behavior did not change over time in the LD hens, whereas inactive behaviors increased with age. During continuous observations, a significant hybrid x period interaction was found for all forms of pecking behavior [F (2, 89) = 4.55-14.80, P < 0.001-0.05]. The LB+ hens showed particularly more severe feather pecking (SFP), which increased with age. In contrast, SFP remained exceptionally low in the LD hens throughout production. Therefore, dual-purpose hybrids should be considered as an alternative to both avoid the killing of surplus male chickens and the development of SFP in laying hen production.

Activity Behaviour of Minipigs Transgenic for the Huntington Gene.

BACKGROUND: To increase the reliability of translating preclinical findings to humans, large animal models, such as the transgenic (tg) Libechov minipig, were established. As minipigs possess high genetic homology with humans and have similarities in anatomy, physiology and metabolism to humans, they are considered for studying neurodegenerative diseases longitudinally. Recently, sleep abnormalities and changes in circadian rhythm in Huntington's disease (HD) patients were acknowledged to present one of the early symptoms in HD. OBJECTIVE: The aim of the present study was to explore the activity behaviour of Libechov minipigs and to investigate whether tgHD and wildtype (wt) minipigs exhibit differences in activity behaviour. Furthermore, it was investigated whether activity assessments may serve as reliable endpoints for phenotyping minipigs transgenic for the Huntington gene. METHODS: Activity behaviour of minipigs was studied by video recording the stables twice a week over a total study period of five weeks for a cohort of five tgHD minipigs and five wt minipigs. Statistical analysis was performed using the linear mixed model. Once a week, the distances covered by two minipigs in focus (tgHD, wt) were measured using the VideoMotionTracker® software. RESULTS: Libechov minipigs showed a biphasic pattern of activity, spending most of the time inactive or grubbing in litter. Differences in activity behaviour (rooting, resting and standing) were detected between wt and tgHD minipigs. The influence of the genotype on behavioural patterns was observed during circadian monitoring. TgHD minipigs covered longer distances on average and during every 24 h observation period than wt minipigs. CONCLUSION: Activity behaviour may be a viable marker for phenotyping minipigs transgenic for the Huntington gene. Video recordings of behavioural patterns provide a non-invasive opportunity to capture potential disease signs. Phenotypic progression including the age of disease manifestation may be explored by documentation of circadian characteristics.

Vocalisation as a Viable Assessment for Phenotyping Minipigs Transgenic for the Huntington Gene?

BACKGROUND: Large animal models, such as the transgenic (tg) Huntington disease (HD) minipig, have been proposed to improve translational reliability and assessment of safety, efficacy and tolerability in preclinical studies. Minipigs are characterised by high genetic homology and comparable brain structures to humans. In addition, behavioural assessments successfully applied in humans could be explored in minipigs to establish similar endpoints in preclinical and clinical studies. Recently, analysis of voice and speech production was established to characterise HD patients. OBJECTIVE: The aim of this study was to investigate whether vocalisation could also serve as a viable marker for phenotyping minipigs transgenic for Huntington's disease (tgHD) and whether tgHD minipigs reveal changes in this domain compared to wildtype (wt) minipigs. METHODS: While conducting behavioural testing, incidence of vocalisation was assessed for a cohort of 14 tgHD and 18 wt minipigs. Statistical analyses were performed using Fisher's Exact Test for group comparisons and McNemar's Test for intra-visit differences between tgHD and wt minipigs. RESULTS: Vocalisation can easily be documented during phenotyping assessments of minipigs. Differences in vocalisation incidences across behavioural conditions were detected between tgHD and wt minipigs. Influence of the genotype on vocalisation was detectable during a period of 1.5 years. CONCLUSION: Vocalisation may be a viable marker for phenotyping minipigs transgenic for the Huntington gene. Documentation of vocalisation provides a non-invasive opportunity to capture potential disease signs and explore phenotypic development including the age of disease manifestation.

Behavioral Assessment of Stress Compensation in Minipigs Transgenic for the Huntington Gene Using Cortisol Levels: A Proof-of-Concept Study.

BACKGROUND: Huntington's disease (HD) is an autosomal-dominant, progressive neurodegenerative disorder with motor, cognitive, behavioral and metabolic symptoms. HD patients exhibit an altered response to stress which is reflected in changes of cortisol levels. Large animal models of HD such as the Libechov minipig are currently explored in preclinical studies to improve translational reliability and assessing behavior is of interest. OBJECTIVE: This study aimed to investigate whether cortisol metabolism and response to stress are changed in minipigs transgenic for the Huntington gene (tgHD) compared to wildtype (wt) animals suggesting that cortisol may be used as a marker for stress in minipigs. METHODS: Thirty-two Libechov minipigs (14 tgHD and 18 wt) were tested before, during and after a stressor, i.e., a hoof trimming procedure, was applied at baseline and after one year. A total of six saliva samples were collected at each assessment and cortisol was measured. In addition, body temperature and respiratory rate were assessed at three pre-determined points during each hoof trimming procedure. RESULTS: All minipigs showed a rise of cortisol in response to the hoof trimming stressor similarly to cortisol changes induced by stress observed in humans. No relevant differences were detected between tgHD and wt minipigs. CONCLUSION: Cortisol testing for the assessment of stress compensation, e.g., during hoof trimming, is feasible and well tolerated in wt and tgHD minipigs. To elucidate the time profile of cortisol responses to stressors further studies with assessments at multiple time points and exploration of the diurnal profiles of cortisol in minipigs are recommended.

Behavioral testing of minipigs transgenic for the Huntington gene-A three-year observational study.

BACKGROUND: Large animal models of Huntington's disease (HD) may increase the reliability of translating preclinical findings to humans. Long live expectancy offers opportunities particularly for disease modifying approaches, but also challenges. The transgenic (tg) HD minipig model assessed in this study exhibits a high genetic homology with humans, similar body weight, and comparable brain structures. To test long-term safety, tolerability, and efficacy of novel therapeutic approaches in this model reliable assessments applicable longitudinally for several years are warranted for all phenotypical domains relevant in HD. OBJECTIVE: To investigate whether the tests proposed assessing motor, cognitive and behavioral domains can be applied repetitively over a 3-year period in minipigs with acceptable variability or learning effects and whether tgHD minipigs reveal changes in these domains compared to wildtype (wt) minipigs suggesting the development of an HD phenotype. METHODS: A cohort of 14 tgHD and 18 wt minipigs was followed for three years. Tests applied every six months included a tongue coordination and hurdle test for the motor domain, a color discrimination test for cognition, and a dominance test for assessing behavior. Statistical analyses were performed using repeated ANOVA for longitudinal group comparisons and Wilcoxon-tests for intra-visit differences between tgHD and wt minipigs. RESULTS: All tests applied demonstrated feasibility, acceptable variance and good consistency during the three-year period. No significant differences between tgHD and wt minipigs were detected suggesting lack of a phenotype before the age of four years. CONCLUSIONS: The assessment battery presented offers measures in all domains relevant for HD and can be applied in long-term phenotyping studies with tgHD minipigs. The observation of this cohort should be continued to explore the timeline of phenotype development and provide information for future interventional studies.