Phosphorus appetite in sheep: dissociating taste from postingestive effects

Area of Science:

• Animal Behavior
• Nutritional Physiology
• Animal Science

Background:

• Nutrient sensing is crucial for animal feed selection.
• The postingestive feedback of nutrients influences learned flavor preferences.
• Phosphorus (P) plays a vital role in animal metabolism and growth.

Purpose of the Study:

• To investigate if lambs can discriminate and associate postingestive effects of phosphorus (P) with feed flavors.
• To determine if learned flavor preferences are modified by P status.
• To test if P preference is inversely related to blood inorganic P concentration.

Main Methods:

• Lambs were depleted of P and conditioned to associate arbitrary flavors with intraruminal infusions of sodium dihydrogen phosphate (NaH2PO4), sodium chloride (NaCl), or water.
• Preference tests were conducted after conditioning and at intervals to assess flavor choices.
• Serum inorganic P levels were monitored throughout the study.

Main Results:

• Lambs initially preferred flavors paired with water, then NaCl, and lastly NaH2PO4 when P levels were high.
• As P levels decreased, lambs developed a preference for flavors associated with NaH2PO4 over NaCl.
• A significant negative correlation was found between flavor intake paired with NaH2PO4 and serum inorganic P levels.

Conclusions:

• Lambs can discriminate postingestive effects of NaH2PO4 and NaCl, associating them with specific flavors.
• Learned flavor preferences are modulated by the animal's physiological need for P.
• This associative learning allows lambs to regulate P intake based on postingestive feedback.