Influence of Sesame Meal on Meat Fatty Acid Profile, and Digestibility in Fattening Lambs of Baluchi Breed

Introduction:

 Sesame with the scientific name ‘Sesamum Indicum’ belongs to the Pedaliaceae family. Sesame seeds have high oil content (42-56%) and crude protein (20-25%), as well as a source of minerals, especially calcium, phosphorus, potassium and iron. The main fatty acids in sesame include: linoleic acid (40.4 to 47.9%), oleic acid (35.9 to 42.3%), palmitic acid (7.9% to 12%) and stearic acid (6.1 to 4.8 %). Historically, the purpose of agricultural research has been focused on increasing production efficiency so that less emphasis has been on improving the profile of food products. Therefore, scientists and producers are interested in research and agricultural activities that can improve the nutritional profile of food products. Changes in animal nutrition can significantly increase the concentration of bioactive components (such as conjugated linoleic acid and omega-3 fatty acids) in animal products. The most effective strategy is to supplement ruminants with different oils or oils rich in linoleic acid or linolenic acid.

Materials and Methods :

In this study, 21 lambs with average initial weight of 30 ±3 kg were used. The experiment was conducted in a completely randomized design with three treatments including 0, 6 and 12% replacement of sesame meal with soybean meal with 7 replicates for 75 days (14 days adaptation). Experimental diets were adjusted using the SRNS transcription software (NRC 2007). Feed was given daily at 8 am and 4 pm. After slaughter of animals, samples of Longissimus dorsi muscle (ribs 12 and 13) were removed from the left carcass and after packaging to measure fatty acids in Freezer-20 ◦C was maintained. The fatty acid composition of sesame meal and muscle were measured. The internal marker was used to determine apparent digestibility of nutrients.

Results and Discussion :

Replacing sesame meal (SM) with soybean meal had no effect on nutrient digestibility and performance (p> 0.05). The effects of added dietary fat on performance of ruminants are reported to be varied. Such variability could be associated with differences between experiments in terms of composition of the basal diet (i.e., energy density and level of grain), level of fat inclusion, fat type and composition (i.e. contents of free and saturated fatty acids), and whether diets were formulated to be isoenergetic. The fact that the rations with fat supplements were isoenergetic and isonitrogenous may explain the absence of significant differences in animal performance. SM supplementation affected the composition of FA in meat of lamb. The SM addition decreased SFA (p < 0.01), SFA: PUFA (p < 0.01) and AI (p < 0.01) while increased MUFA (p < 0.001), PUFA (p < 0.001), CLA and DFA (p < 0.001). Palmitic acid (C16:0) reduced in SM treatment. Since C16 fatty acid has been introduced as a hypercholesterolemic FA, its reduction in meat and adipose tissue is beneficial to human health. Also, stearic acid (C18:0) (p < 0.05) decreased. Endogenous synthesis of MUFA in adipose tissues involves a reduction of C16:0 and C18:0 FA catalyzed by the ∆9 –desaturase activity. It is reported that ∆9 –desaturase expression is influenced by polyphenolic compounds (46). Also, the increase in cis-9 C18:1 proportion in meat of lambs fed SM diets can be explained by the high dietary cis-9 C18:1 level in SM groups, probably combined with slow ruminal biohydrogenation. Oleic acid (cis-9 C18:1) with stearic acids (C18:0) and palmitic (C16:0) to be the most abundant. Palmitic acid increases while oleic acid decreases blood cholesterol, and stearic acid has no effect. The cis-9 C18:1 reduce human LDL-cholesterol and increase HDL-cholesterol concentrations in blood, which result in lower risk of coronary problems. CLA nutrition has been shown to have anti-cancer, anti-obesity, anti-inflammatory, and anti-atherogenic effects, as well as positive effects on serum lipids.

Conclusion :

The results of this study indicated that meat FA composition of lambs can be improved from a human health perspective by inclusion of SM, as a rich source of PUFA. Addition of SM up to 12 % in lambs diet, increased the proportion of CLA, MUFA, PUFA, MUFA: SFA and PUFA:SFA ratio and decreased SFA and AI in meat. However, further investigation is needed to optimize the level of SM incorporation in animal diet.