Impacto do índice de durabilidade do pelete e da dureza da ração no desempenho e outros fatores dos frangos de corte

Abstract

Feed production in the poultry industry worldwide has always faced great challenges, thus motivating the research development aimed to improving the physical and chemical characteristics of the food supplied to broilers and their performance. The feed mill is the most important factor within the poultry production, as 70% of the total costs are attributed to the feed. Thus, it is necessary to develop production techniques that ensure better availability and homogeneity of nutrients in the feed, enabling its efficient utilization by broilers. This study aimed to evaluate the impact of the pellet durability index (PDI) and the feed hardness on the performance and other factors of broilers through a systematic review. Scientific publications on the effect of PDI and hardness on performance and other parameters of broilers were searched in databases. The study was carried out based on 30 articles selected from the databases of the CAPES journals portal: Isi Web of Science, PubMed, Science Direct, Scielo and Scopus. Articles published from 2004 to 2019 were selected (15 years). There were a total of 16,446 broilers aged 1-21, 7-21, 22-42, 14-21, 1-42, and 25-42 days. The most represented aspects were the performance parameters (feed intake (FI), weight gain (WG), feed conversion (FC) and metabolizable energy (ME) of the diet). Metabolizable energy (ME), nitrogen-corrected metabolizable energy (MEn), ileal digestibility coefficient of dry matter (IDCDM), apparent ileal digestibility coefficient of dry matter (AIDCDM), ileal amino acid digestibility coefficient (IDCAA), breast yield, proventricle, gizzard and pancreas weight, proventricular pH and gizzard, starch gelatinization, cecal microbiota and feed mill productivity. The data were adjusted to Pearson's linear statistical model (r) (p <0.05; p <0.01 and p <0.001), in order to measure the correlation degree between the variables. For PDI of 14-21 days and for CR it was 0.75 (p <0.05), WG 0.60 (p <0.05) and FC 0.29 (p <0.05) which were considered low, although significant. For FI of 22-42 days the correlation was -0.67 (p <0.05) and for WG 0.63 (p <0.05). For MEn of 1-21, it was -0.99 (p <0.01), and this is due to the fact that, in this period, the GIT is immature which leads to a highly negative effect. For the IDCAA, from 7 to 21 days the correlation was 0.90 (p <0.01). In this phase, chickens have a greater nutrient utilization due to the digestion kinetics and nutrients absorption, promoting the breakdown of amino acids. For gelatinization of 21-42 days, it was 0.96 (p <0.01), a positive response where the pelletizing temperature is directly proportional to the pellet quality, besides favoring the breakdown of amino acids in the ileum. For the hardness and FI of 14-21 and 22-42 days the correlation coefficient was 0.62 (p <0.05) and 0.74 (p <0.01), although from 7-21 d the correlation was negative -0, 66 (p <0.01). For WG 14-21 and from 22 to 42 d it was 0.55 and 0.78 (p <0.05 and p <0.01). From 7-21 d it was a significant negative of -0.87 (p <0.01), being a consequence of the slow adaptive process of the GIT. For CR 22-42 it was -0.86 (p <0.001). For DM from 1-21 and 7-1 from 0.90 and 0.94 (p <0.001), respectively. AIDCDM and IDCAA of 1-2 d was 0.68 (p <0.01), where chickens showed a decrease in feed selectivity leading to saving more energy during this growth phase. For gelatinization of 1-21d the correlation was 0.70 (p <0.01), a positive result where higher temperature leads to an increase in the surface pellets tension increasing their hardness. The PDI and the feed hardness have a positive or negative impact on the performance and other physiological factors of broilers, considering aspects such as the benefits at the GIT, and the and the organ development in addition to defining the feed mill productivity.