Abstract
ABSTRACT: This study was designed to simulate productive and economic losses due to the withdrawal of antibiotic growth promoters (AGP) from pig diets. Articles that compared diets with AGP (AGP+) or without AGP (AGP–) for pigs were collected from electronic databases and the performance results were entered in a database. A meta-analysis was performed following the sequence: graphical analysis, correlation, and variance-covariance. The performance results observed in the meta-analysis, feed cost, and AGP costs were used to build equations to estimate the economic effect of withdrawing AGP. The database comprised 81 scientific articles containing 103 experiments totalizing 42,923 pigs. Avilamycin (24.7 %) was the most frequent AGP in the database, followed by Colistin (15.4 %), Tiamulin (11.7 %), Tylosin (8.0 %), Lincomycin (9.4 %), and Bacitracin (5.4 %). Weight gain (p < 0.05) increased in AGP+ diets during post-weaning (6.5 %). However, there was no effect of AGP on weight gain of growing-finishing pigs. There was better (p < 0.05) feed conversion in pigs fed AGP+ diets in all rearing phases. Weight gain and feed conversion improved (p < 0.05) with the addition of Avilamycin, Bacitracin, and Tylosin. AGP withdrawal in the post-weaning phase increased feed costs by US$ 0.86 per animal and in growing-finishing phase the increase was US$ 3.11. Thus, pigs fed AGP+ diets have a better performance than pigs fed AGP- diets and the withdrawal of AGP increases feed costs.
Highlights
Antimicrobial additives have been used in animal feed since the 1950s; changes in the use of antibiotics and antibiotic growth promoters (AGP) in several countries indicate a trend to reduce the use of these substances
The criteria for publication selection were: (1) in vivo experimental evaluation of diets with AGP (AGP+) or without AGP (AGP–), no other growth-promoting additive could be present in the AGP– diet; (2) antibiotics were used in subtherapeutic doses, as recommended for growth promoters (Sindirações, 2009); (3) the AGP used was allowed in the Brazilian standard legislation of 2016; (4) the experimental pigs were in post-weaning, growing, or finishing phases; (5) the rates of feed intake, weight gain, and feed conversion or feed efficiency were stated; (6) year of publication was between 1990 and 2018
A negative variation in weight gain was observed in 83 % of comparisons between the treatments AGP+ and AGPv (Figure 1)
Summary
Antimicrobial additives have been used in animal feed since the 1950s; changes in the use of antibiotics and antibiotic growth promoters (AGP) in several countries indicate a trend to reduce the use of these substances. The pressure to reduce and/or ban the use of antibiotics and AGP in animal production is linked to the selection of antibiotic-resistant bacteria, which results in environmental and economic problems worldwide (Tang et al, 2017; WHO, 2018). Other studies have reported positive effects of AGP on pig weight gain and feed conversion (Valchev et al, 2009; Yoon et al, 2014; Li et al, 2017; Silva et al, 2016)
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