Effects of Chia Seeds on Growth Performance, Carcass Traits and Fatty Acid Profile of Lamb Meat

{"Background": "Red meat is an important dietary component in Western countries but is typically low in n-3 fatty acids and high in saturated fatty acids (SFAs) and n-6 fatty acids. Saturated fatty acid synthesis in ruminants is linked to extensive biohydrogenation of dietary unsaturated fatty acids by rumen microbiota, which are then absorbed and deposited as fat in meat. Dietary manipulation strategies, such as including oilseeds rich in polyunsaturated fatty acids (PUFAs), have been used to enhance the fatty acid profile of sheep meat for human consumption. Chia seeds (Salvia hispanica L.) are native to central Mexico and Northern Guatemala and are rich in omega-3 fatty acids (\u03b1-linolenic acid), soluble and insoluble fibers, proteins, minerals, and antioxidants. The seeds contain approximately 35% lipids, 18% protein, and 23% fiber, with chia seed oil containing 64.1 g/100 g total fatty acids as n-3 PUFAs. While chia seeds have been studied in monogastric animals such as poultry and rabbits, studies in ruminants are scarce. This trial aimed to evaluate the inclusion of chia seeds in lamb diets and analyze its effect on growth performance and the fatty acid profile of lamb meat (Longissimus thoracis).", "Methods": "The experiment was conducted in March and April 2021 in Salinas de Hidalgo, San Luis Potos\u00ed, Mexico (22\u00b036'39\" N, 101\u00b042'45\" W, 2100 m elevation, semiarid climate, mean temperature 18.7 \u00b0C, 391 mm annual rainfall). Eighteen male Rambouillet lambs (25 \u00b1 2.4 kg; 3 months of age) were housed in individual cages (1.5 m \u00d7 1.0 m) in a ventilated barn. Three total mixed rations (TMRs) were formulated with 0, 50, or 100 g chia seeds per kg dry matter (DM), with a 50:50 forage-to-concentrate ratio, and randomly assigned to animals (n = 6 per treatment). Lambs had a 14-day adaptation period followed by a 60-day experimental period with ad libitum water and feed offered twice daily at 8:00 and 16:00 h. Feed intake was measured daily allowing up to 10% orts. Lambs were weighed every 15 days before morning feeding. Weight gain was calculated by subtracting initial from final weight; average daily gain (ADG) was calculated from bodyweight changes; feed conversion ratio (FCR) was calculated as dry matter intake (DMI) divided by ADG. After 60 days, feed and water were removed for 12 h, then lambs were desensitized by electrocution and slaughtered via exsanguination. Hot carcass and non-meat component weights were recorded. The hot carcass was refrigerated at 4 \u00b0C for 24 h and cold carcass weight was recorded. Longissimus thoracis muscle samples from the 10th to 13th rib were collected, packed in polyethylene bags, and stored at \u221230 \u00b0C. Fatty acid profiles were analyzed by gas chromatography of methyl-esters using a Stabilwax capillary column (60 m \u00d7 0.25 mm \u00d7 0.25 \u00b5m). Data were analyzed using a completely randomized design with one-way ANOVA (diet as fixed effect) using SAS v.9.2. Growth performance data were analyzed using the 'mixed' SAS procedure with heterogeneous autoregressive (ARH(1)) covariance structure. Significant differences were accepted at p < 0.05.", "Key Results": "Initial bodyweights (25.7, 25.3, 23.3 kg for 0, 50, 100 g chia/kg DM, respectively) and final bodyweights (42.4, 45.3, 43.2 kg) did not differ between treatments (p > 0.05). Total weight gain showed significant differences (p < 0.05): 16.7 kg (0 g), 20.0 kg (50 g), and 19.9 kg (100 g), with both chia-supplemented groups differing from control but not from each other. ADG also differed (p < 0.05): 0.28 kg/d (0 g), 0.33 kg/d (50 g), 0.33 kg/d (100 g). DMI was similar across treatments (1.74, 1.85, 1.78 kg/d; p > 0.05). FCR was 6.2, 5.5, and 5.3 kg DM/kg gain (p > 0.05). Hot carcass weights (18.4, 18.4, 18.6 kg) and all non-meat components (heart, intestines, liver, kidneys, lungs, rumen, testicles, penis, trachea, head, skin) showed no significant differences between treatments. For fatty acid profiles, stearic acid (C18:0) significantly decreased with increasing chia seed inclusion: 56.8 g/100 g fat (0 g), 46.7 g/100 g (50 g), 41.4 g/100 g (100 g) (p < 0.001). Oleic acid (C18:1 n:9) significantly increased: 15.6 g/100 g (0 g), 23.7 g/100 g (50 g), 28.2 g/100 g (100 g) (p < 0.001). Total SFAs decreased significantly: 79.3 g/100 g (0 g), 72.1 g/100 g (50 g), 67.5 g/100 g (100 g) (p < 0.001). Total MUFAs increased significantly: 20.0 g/100 g (0 g), 27.4 g/100 g (50 g), 32.3 g/100 g (100 g) (p < 0.001). Total PUFAs were 0.8, 0.8, and 0.3 g/100 g (p < 0.05). Linolenic acid (C18:3 n-3) remained at 0.1 g/100 g across all treatments (p > 0.05). Palmitic acid (C16:0) increased with chia inclusion: 17.2, 19.8, 21.8 g/100 g (p < 0.05).", "Clinical Implications": "This study demonstrates that supplementing lamb diets with up to 100 g/kg DM of chia seeds can favorably modify the fatty acid profile of lamb meat by reducing total SFAs (from 79.3% to 67.5%) and increasing MUFAs (from 20.0% to 32.3%), particularly oleic acid. These changes may offer cardiovascular health benefits to consumers by improving the fatty acid composition of red meat. However, the lack of increase in PUFAs, particularly \u03b1-linolenic acid, suggests extensive ruminal biohydrogenation limits direct transfer of chia seed omega-3 fatty acids to meat. The absence of negative effects on growth performance and carcass characteristics supports the feasibility of using chia seeds as a feed ingredient. The authors note that higher inclusion levels than those tested might be needed to significantly increase omega-3 concentrations in intramuscular fat."}