Search

1. Two experiments were performed to assess the effect of different amounts of dietary polyunsaturated fatty acids (PUFA) on fatty acid composition of chickens. The contribution of de novo fatty acid synthesis to fatty acid profile was also estimated. 2. In trial 1, different fat sources were blended in different ratios allowing a gradient of dietary PUFA (from 15 to 61  g/kg), keeping added fat constant (9%). In trial 2, PUFA-rich oil was added at increasing inclusion rates (2, 4, 6 and 8%), achieving a dietary PUFA content ranging between 27 and 59  g/kg. 3. Increasing dietary PUFA inclusion resulted in an increase in PUFA deposition, with higher efficiency when dietary fat also provided saturated (SFA) and monounsaturated (MUFA) fatty acids (trial 1). 4. Increasing dietary PUFA in both trials resulted in a decrease in SFA and MUFA concentration in the whole body. 5. The estimated deposition of fatty acids from de novo synthesis was reduced when dietary fat content increased from 0 to 10%, varying between 35·34 and 17·66% for SFA and between 52·70 and 7·01% for MUFA in the whole body. The greater variation range for the MUFA supports the existence of a mechanism maintaining the SFA: (MUFA  +  PUFA) ratio within a specific range in biological membranes. [ABSTRACT FROM AUTHOR]

Abstract: The effects of n-3 fatty acids (FA) on serum thyroid hormones (T3, and T4), lipoprotein lipase (LPL), glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme (ME), and L-3-hydroxyacyl-CoA-dehydrogenase (L3HOAD) activities were studied in chickens fed three diets: a basal diet low in fat and energy (BS) and two diets rich in n-3 polyunsaturated FA (10% linseed oil; LO) or in saturated FA (10% tallow; TA). Dietary FA profiles resulted in different profiles of FA in the tissues as expected. The BS diet caused lower LPL activity and fat deposition compared to the other diets. Chickens fed the LO diet showed lower abdominal fat deposition and higher L3HOAD activities (β-oxidation) and serum T3 levels than those fed the TA diet. There were no differences in lipid synthesis. Lipid β-oxidation may be more relevant than synthesis of FA in the lower fat deposition caused by n-3 FA compared to saturated FA in chicken diets. Higher serum T3 suggest a possible role of this hormone in the lower fat deposition caused by LO. [Copyright &y& Elsevier]

One hundred ninety-two female broiler chickens were randomly distributed into 16 experimental treatments as a result of the combination of 4 levels of dietary polyunsaturated fatty acids (PUFA) (15, 34, 45, and 61 g/kg) and 4 levels of supplementation with αtocopheryl acetate (α-TA) (0, 100, 200, and 400 mg/kg), to determine the modification of the amount and type of fatty acids (FA) deposited in raw and cooked chicken tissues. At 44 d, quantified FA of thighs and breasts were not affected by dietary supplementation with α-TA. Total FA content of breast was less than 15% of the total FA content of thigh. However, increasing the PUFA content of the diet by 46 g, from 15 to 61 g/kg, decreased total FA of thigh 17%, but did not affect FA content in breast meat. Monounsaturated fatty acid (MUFA) and saturated fatty acid (SFA) content of thigh (y) decreased linearly as the inclusion of dietary PUFA (x) increased (MUFA: y = 89.34 - 0.92x, R² = 0.70; SFA: y = 53.81 - 0.43x, R² = 0.57), whereas the relationship between PUFA content of feed (x) and thighs (y) was exponential (y = 92.03 92.03e(-0.0155x), R² = 0.75). A similar response was observed in breast, with less variation and more incorporation of PUFA than thigh. Cooking of thigh meat led to a reduction in total FA content that affected SFA, MUFA, and PUFA in a similar proportion. [ABSTRACT FROM AUTHOR]