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Dietary available phosphorus levels effect in the bone strength of 94 to 125 kg gilts.
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With the objective to evaluate levels of available phosphorus (aP) in diets with or without ractopamine, 112 gilts with high genetic potential for meat deposition with initial weigh of 94.0±2.28 kg were allotted in a completely randomized block design, in a 4 × 2 factorial arrangement (0.109, 0.209, 0.309, and 0.409% aP and 0 or 5 ppm of ractopamin...
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This experiment was conducted to determine the requirement of available phosphorus (aP) for pigs kept in hot environment. Seventy-two pigs (36 castrated males and 36 females) with initial weight of 15.10±0.31 kg were allotted in a completely randomized block design with six treatments (0.107, 0.214, 0.321, 0.428, 0.535, and 0.642% of aP), six repli...
Citations
... These authors recommended that RAC diets should be supplemented with additional available phosphorus to maintain the same bone mineral content as control pigs. Contrary to these results, Campos et al. (2012) fed 4 different levels of available phosphorus to control and RAC pigs, and concluded that feeding RAC at 5 mg/kg for 34 d did not affect bone strength or the percentage of bone phosphorus, calcium, or ash. Pardo et al. (2004) evaluated the effects of phytase and inorganic phosphate in pigs fed 0 or 10 mg/kg of RAC for 28 d and reported that RAC did not adversely affect bone traits compared to control pigs. ...
This review summarizes the effects of ractopamine hydrochloride (RAC) dose (5, 7.5, 10, and 20 mg/kg) on market weight pig welfare indicators. Ractopamine hydrochloride (trade name Paylean) is a β-adrenergic agonist that was initially approved in the U.S. in 1999 at doses of 5 to 20 mg/kg to improve feed efficiency and carcass leanness. However, anecdotal reports suggested that RAC increased the rate of non-ambulatory (fatigued and injured) pigs at U.S. packing plants. This led to the addition of a caution statement to the Paylean label, and a series of research studies investigating the effects of RAC on pig welfare. Early research indicated that: (1) regardless of RAC administration, fatigued (non-ambulatory, non-injured) pigs are in a state of metabolic acidosis; (2) aggressive handling increases stress responsiveness at 20 mg/kg RAC, while 5 mg/kg reduces stress responsiveness to aggressive handling. Given this information, dosage range for Paylean was changed in 2006 to 5 to 10 mg/kg in market weight pigs. Subsequent research on RAC demonstrated that: (1) RAC has minimal effects on mortality, lameness, and home pen behavior; (2) RAC fed pigs demonstrated inconsistent prevalence and intensity of aggressive behaviors; (3) RAC fed pigs may be more difficult to handle at doses above 5 mg/kg; and (4) RAC fed pigs may have increased stress responsiveness and higher rates of non-ambulatory pigs when subjected to aggressive handling, especially when 20 mg/kg of RAC is fed.
... Some studies showed that lower RAC levels did not change ADFI (Pereira et al., 2008;Patience et al., 2009;E. C. Almeida et al., 2010;Campos et al., 2012;Hinson et al., 2012). On the other hand, higher doses of RAC (above 20 or 30 mg/kg) may decrease the ADFI (Watkins et al., 1990;Yen et al., 1990;Crome et al., 1996;Carr et al., 2005;Garbossa et al., 2013). ...
The effect of ractopamine (RAC) supplementation on growth, carcass, and meat quality traits of finishing pigs was studied using a meta-analytical approach. The database was composed of 57 studies published from 2004 to 2016. The dependent variables extracted for the meta-analysis included final BW, ADG, ADFI, feed:gain ratio, HCW, dressing percentage, carcass length, lean yield, back fat thickness, loin muscle area, loin depth, postmortem pH, meat brightness, redness, and yellowness. The studies were grouped by similarity in 3 clusters (C1, C2, and C3) by hierarchical clustering on principle components. The main differences observed between clusters were those of animal initial weight, which increased from C1 through C3. Linear mixed models were used to analyze the data, where studies were assumed as random effect, whereas the total amount of RAC in the diet, cluster, and sex category were considered fixed effects. The interactions between cluster and sex category (barrows, gilts, and mixed sex) and RAC level were also evaluated. Dietary RAC was effective in improving final weight (P < 0.0001), ADG (P < 0.0001), and feed:gain ratio (P < 0.0001) and had a positive effect on HCW (P < 0.0001), lean yield (P = 0.0081), loin muscle area (P = 0.0190), and loin depth (P < 0.0001). In addition, a relatively limited effect on pork quality was observed in the current study. The RAC supplementation was more effective, mainly when pigs started supplementation with higher initial weight, although different responses were observed according to sex category (P < 0.05). There is ample indication that growth and carcass traits could be improved by dietary RAC supplementation. Ractopamine supplementation did not influence the pork quality.
