• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.707-715
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• 2020

An experiment was designed to assess ractopamine supplementation on growth, meat quality and carcass, and fecal scores of pigs. The 96 crossbred pigs ([Yorkshire× Landrace] × Duroc) had an average body weight of 72.8 ± 2.5 kg. Randomized allocation was followed in the allotment of the pigs according to their body weight into 1 of 2 dietary treatments: 1) CON, basal diet and 2) RAC (ractopamine hydrochloride), CON + 1% ractopamine with 12 replication pens per treatment including equal numbers of barrows (2) and gilts (2) per pen. At the end of the experiment, the lean meat percentage was higher (p < 0.05) for the RAC group compared to the CON group. Dietary ractopamine supplementation did not influence (p > 0.05) the growth performance and fecal score throughout the experimental period. In regard to sensory evaluation, higher (p < 0.05) scores for color and firmness were observed in the RAC group than in the CON group. Drip loss (p < 0.05) was higher in the ractopamine fed diet group compared to the control diet group at day 1. Additionally, longissimus muscle was improved (p < 0.05) in the ractopamine treated diet group than in the control diet group. In conclusion, in the early stage, ractopamine supplementation may not influence the growth performance, but it improves the leanness in the meat of finishing pigs.

• Animal Bioscience
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• v.34 no.9
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• pp.1552-1558
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• 2021

Objective: This work was carried out to evaluate the effects of zilpaterol hydrochloride (ZH) and ractopamine hydrochloride (RH) combined with immunocastration on the welfare traits of feedlot Nellore cattle. Methods: Ninety-six Nellore males (average body weight [BW] = 409±50 kg; average 20 mo of age) were divided into two groups according to BW; half of the animals in each group received two doses of an immunocastration (ImC) vaccine in a 30 day interval, and the other half did not receive the vaccine (NoC). Afterward, the animals were housed and fed a common diet for 70 days. Then, they were split into three groups and fed one of the following diets for 30 additional days: control (CO) diet, with no β-AA; ZH diet, containing 80 mg/d ZH; and RH diet, containing 300 mg/d RH. Welfare traits were assessed by monitoring body surface temperature using infrared thermography (IRT) and plasma cortisol and temperament measurements. Results: There was no interaction between sexual condition and diet for any trait. The ImC and NoC groups did not differ in rectal and ocular temperatures. The ImC animals had higher flight speeds (p = 0.022) and tended to have higher cortisol levels (p = 0.059) than the NoC animals. Animals fed ZH and RH did not differ in cortisol levels, respiratory rate, rectal temperature, temperature measured by IRT, or temperament behaviour. Conclusion: The ImC animals showed a less stable temperament during handling practices than NoC, whereas ZH and RH supplementation had no adverse effects on animal welfare.