Thyme and celery as potential alternatives to ionophores use in livestock production: their effects on feed utilization, growth performance and meat quality of Barki lambs

摘要

The effects of including thyme, celery or their mixture (as an alternative to salinomycin ionophore) on nutrient utilization and animal performance were evaluated using Barki lambs. Fifty-five lambs weighing 18.5 +/- 1.1 kg and about 90 +/- 5 days old were stratified into 5 treatment groups and fed: (1) a control diet of concentrates and maize fodder (600:400 on dry matter basis), or the control diet supplemented with (2) 15 g of thyme, (3) 15 g of celery, (4) 15 g of thyme and celery mixture, or (5) 1 g of salinomycin/lamb daily for 288 days. Additives significantly increased (P<0.05) both maize and total intakes, while thyme and thyme-celery significantly increased nutrient digestibility (P<0.05) compared with the control treatment. Celery, thyme-celery and salinomycin treatments decreased (P<0.05) serum cholesterol. Celery increased (P<0.05) final body weight, weight gain and average daily gain without affecting shrunk liveweight, hot carcass weight or dressing percent. Thymecelery mix increased fat thickness of the rib cuts (P<0.001), while thyme, thyme-celery and celery treatments increased (P<0.01) the longissimus muscle area. Salinomycin, celery and thyme treatments increased (P<0.05) the lean proportion and decreased the fat proportion. Thyme, celery and thyme-celery treatments decreased (P<0.001) protein of meat, while thyme and thyme-celery treatments increased (P<0.01) carcass water holding capacity. Salinomycin, thyme and celery treatments decreased (P<0.01) meat brightness score, while celery treatment increased (P<0.05) redness of meat without affecting yellowness, chroma or hue of meat. Overall, results in the present study showed that these natural additives had similar effects to salinomycin, but further studies are necessary to validate the results and their mechanism of action.