Influência da utilização de fibra insolúvel no bem-estar de poedeiras comerciais em dois sistemas de criação

Abstract

The pecking of feathers among laying hens remains one of the main problems faced by the modern poultry industry as it is responsible for cannibalism, a relevant behavior that depresses the welfare of the laying hens and causes economic losses to the farm. The use of lignocellulose in animal diets has been gaining prominence in research, as it contributes to the improvement of feed ingestion and digestion capacity, and may be related to the well-being of laying hens. It was hypothesized that the inclusion of insoluble fibers in the diet increases feed related behavior, prolonging satiety, reducing feather pecking and improves the feathering condition and welfare. Therefore, this experiment was conducted to investigate the effects of the inclusion of insoluble fiber (lignocellulose) in laying diet in two rearing systems: conventional cage system and free-range alternative system on feather damage (feathering score), poultry performance, egg quality, food and social behavior, and physiological parameters. A total of 360 semi-heavy laying hens (Hisex Brown) were used, the experimental design was completely randomized with four treatments in a 2x2 factorial scheme. The treatments were: Treatment 1 = 0.0% lignocellulose in the diet and laying hens in a free-range system; Treatment 2 = 1.0% lignocellulose in the diet and laying hens in a free-range system; Treatment 3 = 0.0% lignocellulose in the feed and laying in cages; Treatment 4 = 1.0% lignocellulose in the feed and laying in cages. Each fiber inclusion level was applied in six replications, the free range replication consisted of a picket with 24 layers, and the cage system was composed of 12 laying, housed in two cages containing six laying hens each. The laying hens were fed a balanced diet according to the nutritional recommendations of the lineage manual, based on ground corn and soybean meal, water and feed available ad libitum. It was evaluate: hen performance, egg quality, feeding behavior and socialization among hens through filming, physiological parameters indicative of welfare as a heterophile:lymphocyte and serum corticosterone, and feather damage score. The data were submitted to analysis of variance and when significant compared by the F test at 5% probability. Free-range hens had higher egg production, feed intake and better feed conversion than laying hens kept in cages. Egg weight was influenced by the inclusion of fiber in the diet, with fiber inclusion the birds in cage system presented heavier eggs, and without the fiber inclusion the birds in the free-range system obtained heavier eggs. The egg density was higher when the birds were kept in cages. It was verified that the laying hens in free range system presented better warping score and lower heterophile:lymphocyte ratio, compared to hens in cages. Plasma corticosterone concentration was lower in the diet with fiber inclusion, regardless of the type of rearing system. The severe pecking and gentle pecking behaviors were more frequent in hens kept in a cage system and consuming a diet without fiber inclusion. Laying hens kept in a free-range system presented a greater variety of behavior inherent to the species, regardless of the inclusion of fiber in the diet.