Phenylalanine requirement of the lactating sow

Area of Science:

• Animal Nutrition
• Swine Physiology
• Biochemistry

Background:

• Phenylalanine (Phe) and tyrosine (Tyr) are essential amino acids.
• Understanding their metabolic interplay is crucial for optimizing swine diets.
• Lactating sows have specific amino acid requirements for milk production and piglet growth.

Purpose of the Study:

• To determine the phenylalanine requirement in lactating sows when tyrosine is in excess.
• To evaluate the impact of varying phenylalanine levels on nitrogen metabolism and amino acid status.

Main Methods:

• A 6x6 Latin-square design experiment with six mature sows.
• Diets supplemented with L-Phe to provide levels ranging from 0.175% to 0.550%, with 0.47% Tyr.
• Measurements included sow milk yield, piglet weight gain, feed intake, and nitrogen balance parameters.

Main Results:

• Sow milk yield and piglet weight gain decreased with longer experimental periods.
• Low phenylalanine diets depressed feed intake and piglet weight gain.
• Nitrogen retention improved with increasing phenylalanine, with optimal levels around 0.285-0.307%.
• Plasma and urine urea nitrogen decreased with higher phenylalanine intake, indicating improved nitrogen utilization.

Conclusions:

• The phenylalanine requirement for lactating sows, in the presence of excess tyrosine, is estimated to be around 0.285% based on nitrogen utilization and urea excretion.
• Adequate phenylalanine levels are critical for efficient nitrogen retention and overall sow and piglet performance during lactation.