The poultry meat industry is faced with various quality issues related to variations in the ultimate pH of breast meat, according to a group of researchers in France led by Cécile Berri of INRA in Nouzilly and including others from Institut Technique de l’Aviculture and Provimi France.

The aim of their study, published in Poultry Science, was to evaluate the possibility to control breast ultimate pH by distributing finishing diets varying in amino acid (AA) and energy content for a short period before slaughter.

Experimental diets were distributed to PM3 broilers on the last three days before slaughter (36 days of age).

They consisted of:

• a control (C) diet (3,150kcal per kg; 200g per kg of crude protein; 10.0g per kg of true digestible lysine (Lys) with adequate amounts of other amino acids (AA) other than lysine
• six diets isocaloric with the control diet including:
  • three lysine-deficient (8.0g per kg) diets with an adequate (Lys−/AA), low (Lys−/AA−) or high (Lys−/AA+) amount of other essential AA calculated in relation to lysine and
  • three lysine-rich (12.0g per kg) diets with an adequate (Lys+/AA), low (Lys+/AA−) or high (Lys+/AA+) amount of other essential AA calculated in relation to lysine, and
• two diets isoproteic with the control but with a higher (3,300kcal per kg; E+) or lower (3,000kcal per kg; E−) energy content.

Broiler feed consumption and growth performance were slightly affected by amino acid and energy content during the finishing period.

Feed intake (days 33 to 36) was lower with the Lys+/AA+ and E+, and FCR between 24 and 36 days was higher with the Lys−/AA− and E− than with the C diet.

Bodyweight on day 36 was lower in Lys−/AA−, Lys+/AA+ and E+ than in C, whereas the breast meat yield and abdominal fatness were not affected by diet.

Lower pH values were observed in broilers fed lysine-deficient diets containing a high level of other amino acids (Lys−/AA+) than in broilers fed diets containing low (AA−) or adequate (AA) amounts of other amino acids.

Berri and co-authors concluded their study shows that it is possible to alter the pH of breast meat by changing amino acid profile over a short period before slaughter, with limited impact on broiler growth and carcass composition.

In their comments, the researchers report that it is possible to raise the pH and improve the processing ability of the meat by increasing the dietary supply of lysine while reducing other amino acids for a short period before slaughter. This opens up new scope for improving and reducing the variation in the quality of poultry meat through nutrition, they suggested.

However, they added, improving feed acceptability and modeling the metabolic response thresholds of the birds to changes in amino acid content is essential before considering the introduction of this new concept in feeding strategies for poultry species. They had noted that dietary treatment had affected feed pellet hardness, which may have affected their results.

Reference

Guardia S., Mi. Lessire, A. Corniaux, S. Métayer-Coustard, F. Mercerand, S. Tesseraud, I. Bouvarel and C. Berri. 2014. Short-term nutritional strategies before slaughter are effective in modulating the final pH and color of broiler breast meat. Poultry Science. 93(7): 1764-1773. doi: 10.3382/ps.2013-03768

July 2014