List of references related to welfare issues with beta-agonists

Scientific studies relevant to animal welfare when the beta-agonists zilpaterol and ractompamine are fed to pigs, cattle, or sheep (listed from the earliest to the most recent)

Marchant-Forde, J.M., et al (2003). The effects of ractopamine on the behavior and physiology of finishing pigs. Journal of Animal Science. 81:415-422.

Ractopamine fed at a relatively high dose made pigs "more difficult to handle and potentially more susceptible to handling and transport stress." This required more pats, slaps, and pushes to move them.
Baszcrak, J.A., et al (2006). Effects of ractopamine supplementation on the behavior of British, Continental, and Brahman crossbred steers during handling. Journal of Animal Science. 84:3410-3414.

Slight differences during handling in a squeeze chute when fed at dose of 200 mg per steer per day. Ractopamine steers entered the chute more rapidly.
Montgomery, J.L. et al (2008). Effects of dietary zilpaterol hydrochloride on feedlot performance and carcass characteristics of beef steers fed with and without monensin and tylosin. Journal of Animal Science. 87:1013-1023.
Cattle fed zilpaterol for 35 days had significantly higher death losses.
Poletto, R. et al (2008). Effects of step up ractopamine feeding program, sex, and social rank on growth performance, hoof lesions, and Enterobacteriaceaae shedding in finishing pigs. Journal of Animal Science. 87:304-313.
Pigs fed 5 mg/kg for two weeks and 10 mg/kg for two weeks of ractopamine had increased hoof lesions.
Grandin, T. (2010). Improving animal welfare: A practical approach.
Described problems at the slaughter plant with sore footed stiff gait in cattle fed beta-agonists.
Poletto, R. et al (2010). Aggressiveness and brain amine concentration in dominant and subordinate finishing pigs fed B-adrenoreceptor agonist ractopamine. Journal of Animal Science. 88:3107-3120.
The pigs were fed 5 mg/kg for two weeks and 10 mg/kg for two weeks of ractopamine. Feeding ractopamine at these doses made gilts more aggresive.
Marcias-Cruz, U. et al (2010). Effect of Zilpateral hydrochloride on feedlot performance and carcasss characteristics of ewe/lambs during heat stress conditions.
Each were fed 10 mg/day/per ewe of Zilpateral. Skin temperature higher in ewe fed Zilpateral.
Blaine, K.L. et al (2011). The effects of shade on the performance, carcass classes, and behavior of heat stressed feedlot cattle at the finisher phase. Tropical Animal Health and Production. 43: 609-615.
Shade improved average daily gain in cattle fed Zilpaterol. Shade also reduced panting compared to no shade.
Grandin, T. (2013). Making slaughter houses more humane for cattle, pigs, and sheep. Annual Review of Animal Biosciences. 1:491-512.
Described observations of stiff sore footed, heat stressed, cattle fed beta-agonists. All these observations were made at the packing plant.
Catalano, D. et al (2013). Physiopathological changes related to the use of ractopamine in swine: Clinical and Pathological investigation. Livestock Science. 144:74-81.
Pigs fed 10, or 20, or 40 mg/kg/diet for the last 3 days had some changes in the dimensions of some internal organs.
James, B.W. et al (2013). Effects of dietary L Carnitine and Ractopamine HCI on metabolic response to handling in finishing pigs. Journal of Animal Science. 91:4426-4439.
Ractopamine was fed at 20 mg/kg for four weeks. Rough handling was compared to quiet gentle handling. The authors concluded "These results suggest that pigs fed 20 mg/kg of RAC are more susceptible to stress when handled aggressively compared to pigs not fed RAC."
Athagde, N.B. et al (2013). Stress susceptibility in pigs supplemented with ractopamine. Journal of Animal Science. 91:4180-4187.
Pigs were fed either 0 or 5 mg/kg or 10 mg/kg for 28 days . Ractopamine had no effect on cortisol, lactate, or skin lesions. Creatine kinase was increased. The authors suggest that this may be due to muscular disorders and more research is needed.

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