Biology subjects

Hazard, D.

Publications and source records attributed to Hazard, D..

3 recordsLinked to original sources

bioRxiv2020

Maternal reactivity of ewes at lambing is genetically linked to their behavioral reactivity in an arena test

In sheep, the bond between the dam and her lambs is established during the first hours of a lamb s life. Genetic variability for behavioral reactivity of ewes assessed in an arena test performed 24 h after lambing has already been reported. However, there is no evidence that this reactivity represents the ewe s maternal reactivity at lambing in outdoor conditions. The objective of this study was to investigate whether or not the behavioral reactivity of ewes in the arena test is genetically related to their maternal reactivity measured at lambing. A total of 935 Romane ewes were studied. The maternal reactivity of ewes at the outdoor lambing site was recorded in response to a human approach and to the handling of the lambs. Their behavioral reactivity was also recorded 24 h post-lambing in the arena test that involved a separation from the litter and a human presence. Flight distance, aggressive reaction, time to restore contact with the litter at the lambing site and maternal behavior scores were moderately heritable (0.18 to 0.34), and vocalizations were slightly heritable (0.16). All of these behaviors were genetically correlated with the behavioral reactivity in the arena test. The highest genetic correlations (from 0.60 to 0.90) were found for maternal behavioral scores, flight distance and high-pitched bleats. In conclusion, behavioral reactivity in the arena test can be used to assess early maternal reactivity in standardized conditions. Such phenotyping could be used for genetic improvement of maternal behavior in sheep.

genetics↗

bioRxiv2020

A non-invasive radar system for automated behavioural tracking: application to sheep

Automated quantification of the behaviour of freely moving animals is increasingly needed in ethology, ecology, genetics and evolution. State-of-the-art approaches often require tags to identify animals, high computational power for data collection and processing, and are sensitive to environmental conditions, which limits their large-scale utilisation. Here we introduce a new automated tracking system based on millimetre-wave radars for real time robust and high precision monitoring of untagged animals. To validate our system, we tracked 64 sheep in a standard indoor behavioural test used for genetic selection. First, we show that the proposed radar application is faster and more accurate than conventional video and infrared tracking systems. Next, we illustrate how new behavioural estimators can be derived from the radar data to assess personality traits in sheep for behavioural phenotyping. Finally, we demonstrate that radars can be used for movement tracking at larger spatial scales, in the field, by adjusting operating frequency and radiated electromagnetic power. Millimetre-wave radars thus hold considerable promises for high-throughput recording of the behaviour of animals with various sizes and locomotor modes, in different types of environments.

animal behavior and cognition↗

bioRxiv2020

PhenoBR: a model to phenotype body condition dynamics in meat sheep

In situations of negative energy balance (NEB) due to feed scarcity or high physiological demands, body energy reserves (BR), mainly stored in adipose tissues, become the main sources of energy for ruminants. The capacity to mobilize and restore such BRs in response to different challenges is of major concern in the current context of breeding for resilience. Body condition score (BCS) is a common, practical indicator of BR variations throughout successive productive cycles, and quantitative tools for characterizing such dynamics at the individual level are still lacking. The main objective of this work was to characterize body condition dynamics in terms of BR mobilization and accretion capacities of meat sheep during their productive lifespan through a modelling approach. The animal model used in this work was the reproductive meat ewe (n = 1478) reared in extensive rangeland. Regular measurements of BCS for each productive cycle were used as the indicator of BR variations. A hybrid mathematical model and a web interface, called PhenoBR, was developed to characterize ewes BCS variations through four synthetic and biologically meaningful parameters for each productive cycle i: BR accretion rate [Formula], BR mobilization rate [Formula], plus the time of onset and the duration of the BR mobilization, [Formula] and {Delta}Ti, respectively. The model converged for all the ewes included in the analysis. Estimation of the parameters indicated the inter-individual variability for BR accretion and mobilization rates, and for the length of the mobilization period. Body reserve mobilization rates were closely correlated between productive cycles. Significant correlations between BR mobilization and accretion rates suggest that the two processes are biologically linked. Parameters kp and kb decreased as parity increased. BR mobilization rate and duration increased as litter size increased, while BR accretion rate decreased. Individual characterization of animals by these parameters makes it possible to rank them for their efficiency in the use of body reserves when facing NEB challenges. Such parameters could contribute to better management and decision-making by farmers and advisors, e.g. by adapting feeding systems to the individual characteristics of BR dynamics, or by geneticists as criteria to develop future animal breeding programs including BR dynamics for more robust and resilient animals.

physiology↗