Effects of hay provision and presentation on cognitive development in dairy calves.

Kelsey C Horvath,Emily K Miller-Cushon,Garet P Lahvis

doi:10.1371/journal.pone.0238038

Abstract

In the dairy industry, feeding management has considerable influence on calf behavioral development, yet there is limited understanding of how aspects of diet or accommodating more varied feeding behavior may affect cognitive development in young calves. The objective of this study was to evaluate effects of provision and presentation of hay on the cognitive ability of pre-weaned dairy calves. Individually-housed Holstein heifer calves were assigned at birth to 1 of 3 treatments: pelleted starter only (n = 10), hay (chopped to 5 cm) and starter provided in separate buckets (n = 12), or hay and starter offered as a mixture (n = 11). During week 5 of age, calves were tested daily in a learning task consisting of a T-maze with a milk reward (0.2 L milk) placed in one arm. Calves were subjected to an initial learning and reversal learning stage, where the reward location was changed to the opposite arm of the maze. Calves received 5 sessions/d until they met learning criterion (moving directly to correct side in 3 consecutive sessions) for initial and reversal learning. Dietary treatment did not affect pass rate or the number of sessions required to pass the initial learning stage. During the reversal learning stage, calves provided only starter had a lower pass rate (0.038, during first 8 testing session) early during testing than calves provided hay separately (0.20; P = 0.020) and tended to have a lower pass rate than calves provided hay as a mixture (0.14; P = 0.057). Calves provided only starter also tended to require more sessions to meet the learning criterion (15.8) than both calves provided hay separately (10.8; P = 0.089) and as a mixture (11.8; P = 0.10). Calves provided hay also kicked less and spent more time sniffing or licking the testing area. The results of this experiment indicate that provision of hay may affect behavioral flexibility in dairy calves.

Highlights

Evidence across species points to an important role of early experience on behavioral development and cognition
Previous evidence suggests that individual ability in a reversal learning task was associated with increased exploratory behavior and reduced latency to begin feeding after movement to a novel housing environment [14]. While these results describe a correlation only, it is possible that factors which improve calf performance in a reversal learning task may have consequences for their subsequent ability to cope with environmental changes
To further evaluate the role of dietary factors in cognitive development in dairy calves, the objective of this study was to examine the effects of hay provision alone, either in a separate feeding location from a conventional pelleted calf starter or as a single diet mixed with starter, on the ability of calves to learn and relearn the location of a reward in a T-maze

Summary

Introduction

Evidence across species points to an important role of early experience on behavioral development and cognition. Calves are separated from the dam at birth, such that all aspects of housing and feeding are under human control and have considerable implications for behavioral development and cognition. Housing calves in social groups, compared to the industry norm of individual housing at birth, is known to broadly affect behavioral development and performance (reviewed by [1]). Dairy calf feeding and cognition individually from birth had impaired ability in a reversal learning task compared to calves housed with social contact [2,3], were more reactive in a novel environment [4], and did not habituate to a novel object over repeated testing [2]. In addition to aspects of social housing, the method of feeding young dairy calves has short and long-term influences on behavior and dietary learning [5] and feeding management factors which accommodate a broader range of natural feeding behavior may influence cognitive development

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