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Abstract

Non-nutritive oral behaviors (NNOBs), defined as abnormal oral behaviours not related to the ingestion of food, are frequently observed in artificially reared dairy calves. Cross-sucking is a common NNOB in calves and is frequently cited as a concern for farmers when making the decision to adopt social housing during the milk feeding period due to perceived risks of permanent teat injuries (i.e., often referred to as ‘blind quarters’) and disease transmission. Given the likely multifactorial cause of NNOBS, including cross-sucking, and the lack of a systematic synthesis of management factors, the primary objective of this thesis was to synthesize research findings on NNOBs. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and the Population, Intervention, Comparison, and Outcome (PICO) framework, literature searches resulted in 76 peer-reviewed studies included in the final dataset for synthesis, making this the most extensive evaluation of NNOB management interventions to date. Our systematic review of the available literature found that interventions mimicking natural behavior consistently reduced and prevented NNOBs, particularly those supporting the motivation to suckle. Feeding milk from a teat (real or artificial), providing high milk allowances (>8L/d) frequently and via a slow flow, along with providing forage, all resulted in a reduction in NNOBs. Although moving from individual to social housing may redirect solitary NNOBs toward pen-mates (cross-sucking), the feeding method often mitigated cross-sucking regardless of housing. Our findings suggest that it is best to implement management strategies to decrease NNOBs during the milk feeding period. This is the first review of the research to date on NNOBs that integrated all major management factors into a single framework. Future research should examine how social dynamics affect cross-sucking in socially housed calves and if certain individuals are more susceptible to engaging in, or receiving, the behaviour.