Impact of purified lignin on performance, rumen health, oxidative stress control and meat quality of lambs fed a high-concentrate diet

This study aimed to evaluate the influence of purified lignin as an additive in high-concentrate diets on performance, ruminal health, meat traits, and oxidative stress control in lambs. Thirty-two crossbred Dorper x Santa Ines sheep with an initial live weight and age of 23 +/- 6.3 kg and 60 days, respectively, were kept in individual pens and fed a diet composed of Cynodon sp. hay (10%) and concentrate (90%). The experimental design was a randomized block with four treatments: control, no additives; MON, 15 mg/kg DM of monensin, a known ionophore; LKR, 12.5 g/kg DM of Kraft lignin; SeE, 0.33 mg/kg of selenium and 100 IU/Icg DM of vitamin E, which are known antioxidants. Blood samples were collected at the beginning and after 29 and 54 days of feeding for the evaluation of antioxidant enzyme activity. After 55 days of feeding, the lambs were slaughtered and the incidence of rumenitis and papillary morphology were evaluated, as well as carcass and meat traits and shelf life. The data were analyzed using the MIXED model of the SAS 9.3 program at a 5% level of significance. The treatments exerted no effect on performance or carcass traits. Animals fed LKR showed a higher incidence of lesions on the rumen wall (P = 0.03). There was no interaction between time and treatment. The treatments exerted no effect on the activity of most enzymes evaluated, but higher peroxidase activity was observed after 29 days of feeding in LKR animals compared to the MON (P = 0.005) and SeE (P = 0.015) groups. After 29 days of feeding, lower catalase activity (P = 0.030) was observed in animals fed MON compared to control, and MON animals showed lower activity compared to SeE after 54 days (P = 0.042). The SeE treatment was effective in maintaining low lipid peroxidation since this treatment exhibited the lowest values throughout the period of simulated display (P = 0.005). Kraft lignin exerted no protective effect on the rumen wall mucosa nor a positive effect on performance but increased the activity of peroxidases, indicating antioxidant activity.