The ostrich (Struthio camelus) as a quasi-ungulate, part 5

Trophic limitations potentially imposed on any homeothermic herbivorous species (non-coprophagous) of a given body size, and the alternative adaptive strategies of digestion available to the animal.

Limitation:
poor quality of food

Responses:

• increased intake, with the effect of substitution of quantity for quality
• prolonged retention and fermentation of fine fraction (while passing the coarse fraction), which requires sacculation in diverticula rather than the main canal, and has the effect of compensating for limitations on gut-fill, or reliance on body-mobility
• prolonged retention and fermentation of all food, including coarse fraction, with the effect of microbial production of energy and protein from cellulose

Limitation:
poor quantity of food

Responses:

• fine comminution of food, with the effect of boosting the surface area for microbial and enzymatic digestion
• prolonged retention and fermentation, with the effect of extending the duration of microbial and enzymatic digestion

Limitation:
wide variation in quality of food

Responses:

• enlargement of hindgut rather than foregut, with the effect of avoiding wastage by fermentation of available digestible protein
• sacculation in diverticula, rather than main canal of gastrointestinal tract, with the effect of promoting the speed of passage of food when the rate of fermentation falls below a critical threshold (i.e. in response to a decrease in quality of food)

Limitation:
poverty of energy, rather than protein, in food

Responses:

• enlargement of hindgut rather than foregut, with the effect of provision for final assimilation in the small intestine

Limitation:
lack of moisture in food

Responses:

• fine comminution, with the effect of retrieval of water from faeces before defecation
• enlargement of hindgut rather than foregut, with the effect of retrieval of water from faeces before defecation

Posted on May 23, 2024 11:57 PM by milewski