**3. Results**

#### *3.1. Growth Performance and Carcass Traits*

Growth performance was not affected (*p* > 0.05) by the addition of algae meal to the experimental rations (Table 1). According to HCW, 22% of the carcasses were classified as class A and 78% as class B, whereas according to fatness most carcasses were within type 2 (60% in comparison to 34% and 6% in types 3 and 1, respectively). The subjective carcass color was pale pink and pink in 65 and 35% of the carcasses, respectively. The lowest HCW and dressing percentage were observed (*p* < 0.05) in ALGMILK, while ALGCON treatment showed the highest values (Table 1). ALGCON treatment had lower and higher percentages of carcass muscle and fat, respectively, than NOALG (*p* < 0.05), while ALGMILK showed intermediate values.


**Table 1.** Growth performance and carcass characteristics of feedlot lambs fed a conventional diet alone (NOALG) or feedlot lambs with competent reticular groove reflex fed the same diet supplemented with 2.5% of algae meal, either mixed in the concentrate (ALGCON) or in the milk replacer (ALGMILK).

1 Within each treatment, 8 pens were used for determination of growth performance (2 animals per pen) and 16 animals were used for determination of carcass traits. 2 Calculated as hot carcass weight/final body weight. 3 Estimated by shoulder dissection. SEM: standard error of the mean. Means with different superscripts between treatments are significantly different (*p* < 0.05).

#### *3.2. Meat Quality Characteristics and Oxidative Stability*

The meat quality characteristics and oxidative stability results are shown in Table 2. Neither the treatment nor the ageing time affected meat pH or DL (*p* > 0.05). CL and WBSF parameters were not modified by the treatments (*p* > 0.05), but were reduced by ageing time (*p* < 0.05). The addition of algae meal to the diet did not affect meat color (*p* > 0.05), apart from the b\* coordinate, which was lower (*p* < 0.05) in NOALG. On the contrary, ageing time influenced (*p* < 0.05) the color coordinates, causing a significant increase in L\* and a\*, as well as a decrease in the b\*, C\* and h◦ parameters in all experimental groups.

The presence of algae meal in the diet tended to increase TBARS (*p* = 0.06), while ageing increased (*p* < 0.05) TBARS. At day 1 of ageing, the DPPH fat was higher (*p* < 0.05) in the ALGCON than in the ALGMILK treatment, with an intermediate value for NOALG, but the differences disappeared (*p* > 0.05) at day 6 of ageing. DPPH water did not differ (*p* > 0.05) among treatments, but decreased (*p* < 0.05) with ageing time. As regards the polyphenol content in the diets, the algae meal supplementation supplied 11.8 mg GAE/100 g, while the amount of GAE/100 g in the NOALG diet was 10.3 mg. The total polyphenols contents in meat were not affected by treatments or ageing.

Regarding oxidative stability, it is worth mentioning that marine algae increased total SFA levels in the ALGCON and ALGMILK treatments (40.3 and 40.2%, respectively, vs. 36.9% of total FA in the NOALG treatment), did not affect total MUFA (38.15, 37.86, and 36.60% of total FA in the NOALG, ALGCON, and ALGMILK treatments, respectively), and raised total omega-3 FA (1.45, 3.94 and 4.96 % of total FA in the NOALG, ALGCON, and ALGMILK treatments, respectively). The increases in the levels of omega-3 FA, EPA, DPA, and, most significantly, DHA, were higher when the algae meal was bottle-fed via RGR, in comparison to algae meal mixed in the concentrate [14].


**Table 2.** Quality characteristics and oxidative stability of meat samples from feedlot lambs fed a conventional diet alone (NOALG) or from feedlot lambs with competent reticular groove reflex fed the same diet supplemented with 2.5% of algae meal, either mixed in the concentrate (ALGCON) or in the milk replacer (ALGMILK).

1 In each time within each treatment, 16 samples were analyzed for each parameter. SEM: standard error of the mean. L\*: lightness; a\*: redness; b\*: yellowness; C\*: chroma; h◦: hue; WBSF: Warner–Braztler shear force; TBARS: thiobarbituric acid reactive substances; DPPH fat: 2-2 diphenyl picryl hydrazyl in fat extract; DPPH water: 2-2 diphenyl picryl hydrazyl in aqueous extract. Means with different superscript letters between treatments (capital) or ageing times (lowercase) are significantly different.
