Effects of Different Hay Feeders, Availability of Roughage on Abnormal Behaviors and Cortisol Circadian Rhythm in Horses Kept in Dry Lots.

The study examines the effects different types of hay feeders and the provision of roughage have on horse behavior and circadian cortisol rhythm, finding that free choice feeding leads to more food waste and weight gain, while slow and automated box feeders limit these issues but may cause adverse behavior changes.

Objective and Study Design

• The study aims to compare behavioural effects and cortisol circadian rhythm in horses when different feeding procedures are adopted: free-choice hay feeding, usage of a slow feeder, and an automated box feeder. Cortisol circadian rhythm (CCR) is the daily cycle of cortisol secretion in an animal’s body, and alterations in this rhythm could indicate stress or changes in behavior.
• The experiment followed a 3 × 3 Latin square design, with 15 polo horses divided into three groups, observed for 15 days under each treatment. This design is particularly useful when dealing with livestock since it can efficiently control for animal-to-animal variability.

Data Collection and Analysis

• Data on horse behaviour was collected through 24-hour continuous behavioural sampling (CBS), and blood samples were collected for CCR analysis every fifteen days. Their body weight was also measured during this time.
• Horses’ behaviours were observed, and the time spent on each was recorded. This data contributed to an analysis of the horses’ time budgets – the distribution of their time across different activities.
• The effects of the different feeding types on these metrics were then investigated using Analysis of Variance (ANOVA), a statistical method that determines whether there are significant differences between group means.

Outcomes

• The study found that horses on free choice feeding consumed and wasted more hay each day and experienced more significant weight gain than those on both slow feeders and automatic box feeders.
• It was observed that horses fed with free choice and slow feeding methods spent more than 50% of their time foraging, which mirrors the behaviour of horses in nature. In contrast, horses with box feeders spent less time eating.
• There were behavioural side effects noted in horses using box feeders. These horses were seen to spend their extra time standing, sniffing the ground, practicing coprophagy (eating of faeces), and displayed more aggression.
• No significant differences were seen in the cortisol circadian rhythm among the horses across various feeding methods, suggesting that none of the feeders induced a stress response.

In summary, while the slow feeder and automatic box feeder minimise waste and weight gain issues associated with free-choice feeding, there may be resultant trade-offs in terms of behavioural changes, especially for box feeders.