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.

ABSTRACT. The aim of this study was to evaluate the effect of conjugated linoleic acid (CLA) supplementation in diets with different energy levels in broiler performance. Birds were offered a starter (1-21 d), grower (22-35 d) and finisher (36-42 d) diets; wherein soybean oil was replaced by CLA. The study consisted of a 3 × 2 factorial arrangement with two CLA levels (0 and 1%) and three energy levels (3050, 3100 and 3150 ME kg-1 diet). During the grower and finisher periods, birds were fed diets with same energy level and CLA supplementation was maintained the same. Growth performance was assessed weekly, and carcass and cuts yield were assessed at 42d. Interaction effect of CLA by energy level was observed in broiler performance and carcass yield throughout the study (p > 0.05). During the overall period (1-42 d) broiler performance was not affected by CLA (p > 0.05).However, CLA supplementation (1%) decreased weight gain (p < 0.05) at 21d, regardless of energy level, with no effects on feed intake and feed conversation rate (p > 0.05). The increase in dietary energy was not able to compensate the negative effect on growth performance of broilers supplemented with 1% CLA at the starter period.

ABSTRACT: The effects of mycotoxins on the productive performance of growing pigs and broilers were evaluated using meta-analytical approach. Two databases were constructed: (1) Broilers, with information collected from 51,497 birds and published in 158 scientific papers from 1980 to 2016; and (2) Pigs, with information collected from 7,743 animals and published in 72 scientific papers from 1980 to 2015. The meta-analyses were performed independently for each specie, following three sequential analyses: graphical, correlation, and variance-covariance. Broilers and pigs challenged by mycotoxins reduced (p < 0.05) feed intake by 9 and 6 %, weight gain by 15 and 11 %, and feed efficiency by 6 and 4 % compared with non-challenged animals, respectively. Aflatoxins were the most studied mycotoxins in both databases. Birds and pigs challenged by aflatoxins reduced (p < 0.05) feed intake by 10 and 8 %, growth by 15 and 11 %, and feed efficiency by 6 and 7 % compared to non-challenged animals, respectively. In both databases, variation on growth performance due to mycotoxins showed a linear relationship (p < 0.05) with the feed intake variation caused by the challenge. The intercepts of the regression-based equations were different from zero and negative, which may indicate that mycotoxins altered the maintenance requirements in challenged animals. In conclusion, both broilers and growing pigs show losses in performance responses and worse nutritional efficiency when challenged by mycotoxins.

ABSTRACT We evaluated the effects of a protease supplementation on the growth performance and intestinal health of broilers. Cobb chicks (392; 1-42 d) were divided into four treatments (seven replicates of 14 birds each). There were two feed formulations: a standard diet (SD) and a low crude protein and digestible amino acids diet (Low CP&AA). The two diets were either supplemented (+P) or not (−P) with a protease (Jefo Protease; 1.25 g kg−1). Performance was evaluated by feeding phases (1-7, 8-21, 21-35, and 35-42 d). On day 28, ileum samples were analyzed by a morphometric index for histological alterations (I See Inside Scoring System – ISI). Broilers fed the Low CP&AA had a poor feed conversion ratio (FCR); however, the addition of the protease to the Low CP&AA positively affected FCR and body weight gain and promoted a performance similar to the group fed SD−P. Birds fed diets supplemented with the protease presented the best ISI morphological index, mainly as a result of the low number of alterations regarding the lamina propria, epithelial thickness, and enterocyte proliferation. It is possible to conclude that the enzyme improves feed conversion and lamina propria, epithelial thickness, and proliferation of enterocytes index of broiler chickens when added to a standard diet or with a low crude protein and digestible amino acids diet.

RESUMO Estudou-se a via de fornecimento de cloreto de sódio (NaCl) – água ou ração – sobre o desempenho de frangos de corte, consumo de água, desenvolvimento dos órgãos, metabolizabilidade da matéria seca (MMS), retenção de nitrogênio (RN), energia metabolizável aparente corrigida para nitrogênio (EMAn), matéria seca das excretas (MSex) e composição de carcaça. Foram utilizados 120 frangos da linhagem Ross 308, distribuídos em três tratamentos com quatro repetições de 10 aves cada, num delineamento completamente casualizado. De um a sete dias de idade foram submetidos a três formas de suplementação de NaCl (0,47% de Na): 100% na ração; 50% na ração e 50% na água (50% ração:50% água); e 100% na água. Durante o período de oito a 21 dias as aves receberam uma dieta única, com NaCl via ração. De um a sete dias não houve diferença no Consumo de Água, Consumo de Ração e Ganho de Peso; porém, NaCl via água proporcionou melhor CA do que por ambas as vias (p < 0,07). Aos 21 dias de idade não foram observadas diferenças significativas no desempenho, no peso relativo do coração, fígado e moela e no comprimento relativo do intestino. Não houve resposta à via de fornecimento para EMAn e MSex em pintos de quatro a sete dias de idade; no entanto, as aves que receberam o NaCl via água de bebida, exibiram menor MMS e RN (p < 0,05) no mesmo período. Conclui-se que o NaCl pode ser adicionado tanto na ração quanto na água, sem ocasionar prejuízos ao desempenho produtivo dos frangos de corte na fase pré-inicial.

SUMMARY It was investigated the way to provide NaCl -by water or feed- on performance, water intake, organs development, dry matter metabolizability (DMM), nitrogen retention (NR), apparent metabolizable energy corrected for nitrogen (AMEn), dry matter of excreta (DMEx) and carcass composition (CC) of broilers. One hundred twenty one-day-old male Ross 308 distributed in three treatments with four replications of ten birds each, in a completely randomized design, were subjected to three ways to supply NaCl (0.47% of Na): 100% in diet, 50% in diet and 50% in water (50:50), and 100% in water during the pre-starter period (one to seven days). During the starter period (eight to 21 days) the birds received a unique diet, with NaCl in diet. From one to seven days, there were no significant differences on water intake, feed intake and weight gain; but NaCl in water provided better feed conversion than in both ways (p < 0.07). At 21 d, there were no significant differences in performance, relative weight of heart, liver and gizzard, and relative length of intestine. There was no response to supply way for AMEn and DMEx in chicks from four to seven days; however, birds receiving NaCl via drinking water, exhibited lesser DMM and NR (P < 0.05) in the same period. It was concluded that NaCl can be added in both feed and water to pre-starter chicks.