| In this study,120 AA broilers of 1-day age and similar body weight were randomly divided into 4 groups with 6 replications and 5 chickens in each group.Broiler chicken pellet diets were formulated using faba beans of different crushed particle sizes(565,625,796,and 901 μm).The particle size distribution and physical and chemical properties of broiler diets were determined by in vitro experiments;the effects of crushed broad bean particle size on broiler growth performance,gastrointestinal tract development,cecal microflora,and tibia development were explored based on the "gut-bone" axis through feeding experiments and then examined.The suitable crushing particle size of broad beans in feed further reveals the influence mechanism of feed crushing particle size on bone metabolism and bone development of broiler chickens and provides a theoretical basis for the scientific utilization of broad beans in broiler feed.Results1.Effects of particle size of Faba bean on the grain size distribution and physicochemical properties of diet in broilers.The Dgw of faba bean with sieve pore sizes of 3mm,4mm,5mm,and 6mm were 565,625,796 and 901 μm,respectively.Through granulation of powdered formula feed,the relative ratios of 1-14 d and 15-28 d broiler diets with particle sizes of 565 μm,625 μm,796 μm,and 901 μm were reduced by 1680,1191,841,and 420 μm,respectively,and the ratios of 594 and ≤ 250 μm were increased.The dietary hardness of broilers decreased significantly with the particle size of faba bean from 1 to 14 days(P < 0.05),but there was no significant difference among the four groups(P > 0.05).At p H=2.5,the dry matter solubility of 1-14 d broiler diets was decreased and the water retention capacity of 1-14 d and 15-28 d diets significantly increased with the faba bean particle size increase at p H=2.5.When p H=5,the dry matter solubility of 1-14 d and 15-28 d broilers increased significantly(P < 0.05).However,faba bean particle size did not affect the dry matter solubility of 15-28 d broiler diets at p H=2.5,and there was no significant difference in water retention capacity of faba bean particle size to 1-14 d and 15-28 d broiler diets at p H=5.2.Effects of Faba bean Particle size on growth performance and Gastrointestinal Development of broilers.The ADG of broilers in 1-14 days and 15-28 days increased with the faba bean particle size increase,while the FCR decreased.The ADFI of broilers in the 625 μm group was significantly higher than that of 565 μm,796 μm,and 901 μm.However,the faba bean particle size in 15-28 days had no significant effect on the ADFI of broilers.The apparent metabolic rate of dry matter,crude protein,crude fat,and energy of broilers was significantly affected by the particle size of faba bean from 1 to 14 days,and increased with the increase of the particle size of faba bean,but had no significant effect on the apparent metabolic rate of Ca.The apparent metabolic rate of total energy in the 565 μm group was significantly lower than that in the other three groups(P < 0.05).Still,there was no significant effect on other nutrients(P > 0.05).The group with 901 μm particle size of faba bean significantly increased the relative weight of muscle and stomach and decreased the relative weight of glandular stomach and cecum(P < 0.05).With the increase of the particle size of faba bean,the villus height and crypt depth of jejunum in the 901 μm group were significantly higher than those of 565 μm(P < 0.05),and the villus hidden ratio of 796 μm and901 μm was significantly higher than that of 565 μm(P < 0.05).In ileum morphology,villus height,and villus concealment ratio increased significantly with the increase of faba bean particle size(P < 0.05),but faba bean crushing size had no significant effect on the crypt depth of ileum,relative weight,and relative length of the small intestine(P > 0.05).3.Effects of particle size of Faba bean on cecal microflora and short-chain fatty acids in broilers.The contents of SCFAs,propionic acid,and butyric acid in cecum increased with the increase of faba bean particle size,in which the SCFAs of broilers in the 901 μm group was significantly higher than that in the 565 μm and 625 μm groups.The contents of propionic acid and butyric acid in the 901 μm group were significantly higher than those in the other three groups.The particle size of faba bean significantly affected the richness and diversity of the cecal microbial community.At the gate level,the relative abundance of Bacteroides in the intestinal flora of the 901 μm group increased significantly,while the relative abundance of thick-walled bacteria decreased significantly(P < 0.05).At the family level,the Clostridia＿UCG-014 of the901 μm group was significantly lower than that of 796 μm,and the number of lactic acid bacteria in cecal microorganisms of broilers increased gradually with the increase of faba bean particle size in the diet.At the genus level,the UCG-014 of Clostridium in the 625 μm and 796 μm groups was significantly higher than that in the 901 μm group(P < 0.05).With the increase of particle size of faba bean,the relative abundance of Vibrio succinate,UCG-005,and rumen cocci in cecum contents of broilers decreased significantly.4.Effect of Faba bean Particle size on tibia Development and Physicochemical Indexes of broilers.The diameter of the tibia in the 796 μm and 901 μm groups was significantly higher than that in the 565 μm group(P < 0.05),and the phosphorus content in the tibia in the 901 μm group was significantly higher than that in 625 μm group(P < 0.05).With the increase of faba bean particle size,the maximum bending deformation,maximum load,and the number of bone trabeculae of the tibia increased significantly(P < 0.05),and the bone mineral density of 565 μm and 901 μm group was significantly higher than that of 625 μm group(P < 0.05).The particle size of faba bean had no significant effect on the relative bone weight,relative bone length,Ash,and calcium content,elastic modulus,trabecular thickness,and trabecular separation of the tibia in broilers(P > 0.05).The contents of PⅠNP and OPG in the serum of broilers in the 901 μm group increased significantly.The content of TRACP-5b in the serum of the 625 μm group was significantly higher than that of the other three groups.With the increase of faba bean particle size,the expression of OPG increased significantly,while the expression of RANKL and TNF-αdecreased significantly,and the RANKL/OPG ratio of 625 μm broilers was the highest.The contents of calcium,phosphorus,OCN,ALP,I-CTX and the expression of Runx2 in the serum of broilers were not affected by the particle size of faba bean.When the particle size of faba bean was 796,901 μm,the metabolic rate of nutrients in broilers ADG and 1-14 d broilers was significantly increased,the FCR was decreased,and 901μm group promoted the development of muscle and stomach in broilers to some extent.Improve the intestinal morphology of jejunum and ileum,increase the contents of propionic acid and butyric acid in the cecum of broilers,and inhibit tibia bone resorption by inhibiting TNF-α and RANKL gene expression and up-regulating OPG gene expression,and finally promote tibia development and improve tibia quality. |
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