## 3 Results and Discussion
### Total Lipid, Cholesterol and Fatty Acid Composition
Genotype is also a source of variation; it was demonstrated that slow-growing chickens have a higher desaturation activity which allow them to efficiently convert the dietary FA precursor of the n-3 family (linolenic acid) into long-chain PUFAs such as eicosapentaenoic (C20:5, EPA) and docosahexaenoicenoic (C22:6, DHA) acids (Stein  
different effects of pea administration on FA profile could be due to the different kind of pea seeds used (micronized-dehulled pea, irradiated pea seeds or raw pea seeds), the levels of inclusion in the diet, the broiler chicken genotype and also the rearing conditions. An interaction effect of diet and genotype (\(p\) = 0.064) on the eicosadienoic acid (C20:2 n-6) content was observed. This result highlights that the pea inclusion lowered the levels of C20:2 in both genotypes, however the reduction was more marked among KB birds (KB-SOY: 0.45%; NR-SOY: 0.34%; KB-PEA: 0.34%; NR-PEA: 0.32%; \(p\) = 0.064). In the present study, the genotype slightly affected the FA profile of breast muscle. Meat from the KB group showed a higher content of ALA (\(p\) < 0.05) and of eicosadienoic acid (C20:2 n-6) (\(p\) < 0.01) as compared with the NR group. The predominant FAs in breast muscle in all experimental groups were palmitic (C16:0) and stearic (18:0) acids such as SFA, oleic acids (C18:1n-9) such as MUFA, and linoleic (C18:2 n-6, LA) and arachidonic (20:4n-6, ARA) acids such as PUFA. As reported in a recent review [37], medium-growing and even more slow-growing chickens showed: i) a greater expression of fatty acid desaturase 1 and 2 (FADS1 and FADS2, involved in the metabolism of long-chain PUFA, LC-PUFA); ii) a higher activity of delta-6 and delta-5 desaturases which introduce double bonds in essential FA to obtain LC-PUFA; consequently, a higher LC-PUFA in the breast meat compared to fast-growing chickens. It has also been reported that there are many factors affecting PUFA metabolism and the substrate preference of the delta-6 desaturase for LA or ALA, such as species, genotype, age, sex, diet, and rearing system (reviewed in [PERSON] et al. [41]). The nutritional ratios were significantly affected by diet. The pea diet increased (\(p\) < 0.05) the n-6/n-3 ratio in broiler meat (from 16.43 to 18.92); these values are particularly high considering the current nutritional recommendations for human diets, which suggest that this ratio should not exceed 4.0. On the contrary, [PERSON] and [PERSON] [30] found a significant decrease of this ratio in pea group as compared to soy group (8.57 vs. 9.88, respectively). The P/S ratio was higher (\(p\) < 0.01) in pea-fed birds as compared with soy-fed ones. However, the P/S values observed in the present study are favourably high (ranging from 0.78 to 0.89). From a nutritional point of view, a higher P/S ratio is recommended; indeed, it should be increased to above 0.4 [42]. The AI and TI represent criteria for evaluating the level and interrelation through which some FA may have atherogenic or thrombogenic properties, respectively. Diet and genotype did not affect the AI and TI indices (\(p\) > 0.05). Similarly, [PERSON] and [PERSON] [30] did not find any significant effect of pea inclusion on the above-mentioned indices with similar values for AI (0.55 and 0.58 for soy and pea, respectively), but lower values for TI (0.55 and 0.56, respectively) as compared to our results. The AI and TI values found in the current study can be considered similar with those reported by [PERSON] et al. [43] in ducks fed yellow lupin.