Received: 01-05-2017 / Accepted: 09-06-2017
For establishment of the legal documents for controlling the use of Ractopamine (Ract) and Salbutamol (Salb) as feed additives in pig production, the experiment was carried out to evaluate the impact of supplementation of Ractopamine and Salbutamol on growth performance, and more importantly, the excretion behaviors of these additives and their residues in some edible tissues. The tested diets were (i) basal diet without any supplementation of either Ract or Salb (Control diet), (ii) basal diet added with 10ppm Ract (Ract diet), and (iii) basal diet added with 8 ppm Salb (Salb diet). Forty five fattening pigs with initial average body weight of 60 ± 3,0 kg were randomly allocated to the three treatments. Pigs were fed the experimental diets for the first 30 days (phase 1) following by a common basal diet to all the three treatment groups for another 30 days (phase 2). Each treatment consisted of three replicates with 5 pigs each. The nutrient requirements of the basal diet were formulated according to recommendation for the commercial pigs raised under the condition of Vietnam. Growth performance and carcass quality were accessed and Ract and Salb residues in urine and some tissues were tested after withdrawing the supplemented additives (phase 2). The results showed that supplementation of either Ract and Salb to the finisher diet significantly enhanced performance in pigs in terms of weight gain by 13.2% and 16%, respectively) but decreased FCR by 15.8% and 20.6%, respectively. Moreover, the Racr and Salb supplementation to diet improved some carcass traits as well as lean meat colour. Regarding urinary excretion, pigs fed Ract and Salb needed five and seven days, respectively, to completely excrete via urine. After withdrawing, the residues were still detectable in the fat and lean tissues in pigs fed either Salb or Ract until 5 days and became negative on 6 days in both groups. This result should be taken into consideration for establishing the protocol in controlling these prohibited substances as feed additives in pig production.
