Nutrição in ovo: inoculação de carboidratos em ovos embrionados de frangos de corte - revisões sistemáticas e metanálises

Abstract

The increase in reproductive capacity resulting from genetic improvement in broilers has increased the need for an adequate nutritional intake for the embryonic stage, since the amount of nutrients in the egg may not meet the needs to achieve optimal post-hatching performance. Therefore, the aim of this study was the development of systematic reviews and meta-analyses that could contribute to evaluate the use of carbohydrates in the in ovo nutrition of broiler chicken, demonstrating the effects of the technique on hatchability rate and performance. To this end, two systematic reviews and meta-analyses were performed. In the first one, we tried to define which carbohydrates and the best methodology for in ovo inoculation of these nutrients based on the hatchability parameters (hatchability and hatch weight) and/or post-hatching (performance) in broiler chickens. The search for scientific articles was carried out in September 2021 in eight databases (Embase, Academic Google, Scielo, Science Direct, Scopus, Capes Periodicals, Pubmed and Web of Science), using the following combination of keywords: (carbohydrate AND "in ovo"). We only selected the articles that described the carbohydrates inoculation in embryonated broiler eggs, which used a placebo group and presented the variables of interest. The meta-analysis was performed using the random effects model to calculate the confidence interval (CI) between the differences in the carbohydrate inoculated group and the placebo control. Publication bias was assessed using a funnel plot. The most studied carbohydrate was glucose (57% of the studies). Most carbohydrates, with the exception of dextrin and maltose, reduced (P<0.05) hatchability. Excluding dextrin, all carbohydrates increased (P<0.05) hatch weight. Dextrin or glucose inoculation increased (P<0.05) weight gain after hatching. Only glucose increased (P<0.05) feed intake. There was no effect (P>0.05) of carbohydrate inoculation on the feed conversion ratio. Amnion inoculation increased (P<0.05) weight gain and reduced (P<0.05) feed conversion, however, it decreased (P<0.05) hatchability, as well as air chamber inoculation and in the egg yolk. On the other hand, albumen inoculation increased (P<0.05) hatching weight and weight gain and reduced (P<0.05) feed conversion. The inoculation of solutions between the 7th and the 10th day of incubation, using deionized water as a vehicle improved (P<0.05) all performance parameters without influencing (P>0.05) hatchability. In the second meta-analysis, only articles containing glucose inoculation were analyzed, aiming to determine the most appropriate amount and best methodology for using this nutrient in ovo. The methodology of this meta-analysis was similar to that described above. In ovo inoculation of 75 and 100 mg of glucose increased birth weight and weight gain, without influencing hatchability. The dose of 75 mg/egg, in addition to improving the mentioned parameters, reduced the feed conversion rate. It is concluded that in ovo inoculation with carbohydrates can be used to improve the performance of broiler chickens, with dextrin being the most suitable carbohydrate, followed by glucose (at a dose of 75 mg/egg) and maltose. The solutions should be inoculated into the albumen between the 7th and the 10th day of incubation, using deionized water as a dilution vehicle.