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Barrows and gilts (n = 210/gender) were used to test the effects of crystalline AA supplementation of reduced CP diets on fatty acid composition of the LM and subcutaneus fat from the jowl from growing-finishing pigs. Animals were blocked by BW, and pens (6 pigs/pen) within each block and gender were assigned randomly to either corn-SBM diets (C) devoid of crystalline LYS and formulated to 95% SID AA requirements or 1 of 4 reduced crude protein (RCP) diets. During the last 3-wk feeding phase, 10 mg/kg of ractopamine clorhidrate were included in all diets. Jowls and a subsample of whole pork loins (2 loins/pen) were captured during carcass fabrication, and the LM and s.c. fat from each jowl was freeze-dried for determination of fatty acid composition.
The LM from barrows had greater (P < 0.001) proportions of SFA than the LM from gilts, whereas LM MUFA content increased in the LM of barrows but decreased in the LM of gilts with decreasing dietary CP (linear RCP × gender, P = 0.037). Conversely, LM PUFA composition increased in gilts and decreased in barrows with decreasing dietary CP (linear RCP × gender, P = 0.056). Jowl fat from barrows had more (P = 0.008) SFA and less (P <0.001) PUFA than jowl fat from gilts, whereas the proportions of SFA –particularly palmitic and stearic acids– and PUFA –specifically linoleic acid– in jowl s.c. fat decreased (linear, P = 0.019) with decreasing dietary CP. Also, weight percentages of all MUFA, especially oleic acid, increased (linear, P <0.001) as dietary CP was reduced in the diet.
Results indicate that the fatty acid composition of pork lean and fat were altered by reducing dietary CP, and the pattern of increased MUFA composition of jowl s.c. fat may imply enhanced de novo synthesis in pigs fed RCP diets supplemented with crystalline AA.
Young, A.N., Apple, J.K., Yancey, J.W., Johnson, T.M., Tsai, T.C. and Maxwell, C. V. 2014. Effects of amino acid supplementation of reduced crude protein (RCP) diets on fatty acid compositions of subcutaneous fat and muscle. J. Anim. Sci Vol. 92, E-Suppl. 2. Page 619, abstract 1247.