Ingestive Behavior and Feeding Practices in Horses

Chapter Contents

  • Ingestive behavior
    • The transition from milk to solids
    • Behavior associated with ingestion
    • Food selection and rejection
    • The relationship between nutrition and behavior
    • Grazing
    • Dysphagia
    • Taste tests
    • Anorexia and hypophagia
    • Hyperphagia
    • Natural influences on food intake
    • Social factors
    • Lactation and seasons
    • Time-budgeting
    • Human influences on food intake
    • Oral stereotypies
    • Drinking
    • Variety
    • References

The Transition from Milk to Solids

  • Foals begin nibbling grass from the first day of life, often choosing grass on raised ground to avoid spreading their forelegs.

  • Gradual increases in exploration and intake of solid foods occur as foals develop techniques to access vegetation, particularly flexing their knees to reach ground-level food.

  • The initial phase of interacting with grass and drinking water is very brief, often lasting less than one day.

  • Significant increases in time spent grazing do not typically happen until around 4 months of age.

  • Consumption of non-grass substrates, such as clay, bark, twigs, leaves, and humus, has been observed in adult equids, suggesting that moderate intake may be adaptive and provide essential trace elements or improve gut motility.

  • The importance of learning about food sources can heavily impact biological fitness; for instance, a study showed that male foals had higher neonatal mortality rates during nutritionally poor years compared to better years.

  • Foals develop the ability to select safe foods, avoiding poisonous plants while usually feeding when mothers are present. Domestic foals may steal from their dam's feed or be provided separate concentrate feeds.

  • A balanced diet is necessary for bone formation, but concentrated feeds must be restricted to avoid gastric acidity issues. Care must be taken to prevent developing stereotypic behaviors related to diet composition.

    • Study by Nicol et al: Foals fed a starch-and-sugar diet were more distressed and less settled than those on a fat-and-fiber diet during weaning, indicating significant behavioral differences related to diet.

Behavior Associated with Ingestion

  • Grazing as a foraging method develops more efficiency as foals mature. Juveniles learn to avoid areas where adults eliminate waste.
  • The mechanism of food selection involves using the upper lip to isolate chosen plants and then passing them to the teeth for chewing.
  • Social facilitation enhances food selection learning; horses learn faster in groups than alone from observational learning, improving their efficiency in finding food.
  • Foals between 1-6 weeks engage in exploratory grazing, mouthing plants, with coprophagy peaking during exploration to learn about food through tasting maternal feces.
  • Spatial memory is developed as valuable food patches are revisited over time, aiding in environmental navigation and foraging efficiency.

Food Selection and Rejection

  • Horses possess preferences and aversions to maintain correct nutrition while avoiding toxic plants, greatly influenced by post-ingestive feedback.

  • The concept of specific hunger indicates that horses may select foods that alleviate specific nutrient deficiencies, though they may also eat for pleasure.

  • Studies have shown that ponies change their feeding habits in response to diet dilution by increasing meal sizes while decreasing frequency.

  • Sensory analysis through visual and olfactory qualities, followed by gustatory feedback, aids in differentiating beneficial from harmful feeds. A learned aversion can occur if food provides negative post-ingestive consequences.

  • The relationship between food and illness can create strong aversions, potentially leading to rejection of certain foods in the future.

Grazing

  • Grazing is preferred in adult horses, but browsing is also used when grass is scarce. Horses typically favor legumes, and young plant materials over less beneficial options.
  • Concerns related to pasture management include selective grazing leading to nutrient deficiencies caused by fecal contamination.

Natural Influences on Food Intake

  • Group size and social hierarchy significantly impact feeding behavior, with leaders affecting grazing timing.
  • Mares tending to increase grazing time during lactation while social influences affect feeding time and behavior.
  • Seasonal variation and environmental factors like biting flies and weather significantly shift grazing patterns and durations.

Time-Budgeting

  • Free-ranging horses graze for 16-17 hours daily, with peaks during early morning and late afternoon. Time spent grazing decreases significantly with low forage availability.
  • Horses’ stereotypical feeding patterns are disrupted in stabling situations where movement and social facilitation are constrained.

Human Influences on Food Intake

  • Domestic feeding practices significantly alter natural behaviors, often leading to digestive issues when traditional feeding ratios of concentrates vs. forage are disturbed.
  • Environmental enrichment (like providing forage at varying heights) may help promote natural behavior. Changes in diet composition also lead to behavior modifications, such as oral stereotypies.

Oral Stereotypies

  • Included behaviors like crib-biting and wood-chewing, mostly linked to feeding management practices and dietary deficiencies.

Dysphagia

  • Causes range from dental issues to poisoning affecting swallowing and oral function.

Anorexia and Hypophagia

  • Pain and social hierarchy changes influence intake, with management focusing on diet modifications to improve consumption in ill horses.

Hyperphagia

  • The horse’s tendency to have substantial appetites can lead to colic and metabolic disorders due to rapid consumption of food.

Conclusion

  • Dietary influences are pivotal in shaping nutritional needs and subsequent behaviors in horses; understanding these relationships can enhance animal welfare and management practices.

References

  • The notes are based on various studies and research on equine ingestive behaviors and feeding practices, providing insights into the physiological and behavioral implications of equine nutrition.