Effects of feed form and feed particle size on growth performance,carcass characteristics and digestive tract development of broilers

This study was conducted to evaluate the effects of feed form(mash and crumble-pellet) and feed particle size(fine, medium and coarse) on growth performance, carcass characteristics and digestive tract development of broilers. A total of 1,152 one day-old Ross 308 mixed-sex broilers were used in a factorial arrangement(2×3) based on a completely randomized design with six replicates of 32 birds each.Higher average daily gain(ADG) and average daily feed intake(ADFI) were observed(P < 0.01) for birds fed the crumble-pellet diets(CPD) than for those fed the mash diets(MD) during starter, grower and the entire experiment period. From d 1 to 40, birds fed CPD had a higher(P < 0.01) body weight(BW) than those fed MD. Birds fed CPD had a lower(P < 0.01) feed:gain ratio(F:G) during the starter phase than those fed MD. Medium or coarse particle size increased(P < 0.01) ADG and ADFI during the starter phase, but birds fed fine particle size diets had lower(P < 0.01) F:G during the grower phase. In MD,medium and coarse particle sizes resulted in higher(P < 0.05) BW, ADG and ADFI than fine particle size during the whole experiment. In CPD, particle size had no significant effect on growth performance, as indicated by a feed form × particle size interaction(P < 0.05). At 41 days of age, ten birds per treatment were randomly selected and killed for slaughter yields and digestive tract characteristics determination.It was shown that particle size and feed form alone had no significant effect on slaughter yields, so changes was the feed form × particle size interaction. The relative empty weight of the gizzard was greater(P < 0.01) and the relative length of the ileum was longer(P < 0.05) in birds fed MD than in those fed CPD. Overall, CPD improved growth performance during the entire period of the study with effects being less evident during the finisher phase than during the starter and grower phases, and the effect of feed particle size varied depending on feed form.

Effects of phytonutrients on growth performance, antioxidative status,and energy utilization of broilers fed low energy diets

Two experiments were conducted to investigate the effects of phytonutrients(PN)on growth performance.antioxidant status,intestinal morphology,and nutrient utilization of birds fed low energy diets.In Exp.1.a total of 1.440 one-day-old Ross 308 male broiler chickens were randomly divided into 3 treatment groups,with 16 replicates per treatment(48 pens;30 birds per pen).Birds in treatment 1 were fed diets with normal energy content(NE).Birds in treatment 2 were fed NE diet but with 60 kcal removed(LE).Birds in treatment 3 were assigned to LE diet supplemented with PN(LE + PN).Results indicated that LE diet increased feed conversion ratio(FCR)compared with NE from d 1 to 38.while LE + PN diet prevented this response(P= 0.02).At d 26.birds in the LE + PN group had the highest ileal and jejunal villus height to crypt depth(VH:CD)ratio.At d 39.PN supplementation improved ileal and jejunal VH:CD ratio,compared with LE group.Moreover,birds fed PN diets received a better economic profit,In Exp.2,360 one-day-old Ross 308 male broiler chickens were used in a metabolism study.The treatments used in Exp.2 were the same as those in Exp.1,with 4 replicates(pens)and 30 birds in each replicate.Dietary apparent metabolism energy(AME),energy and protein digestibility were determined between 21 and 28 d of age.Results showed that chickens fed LE + PN diet tended to have greater AME(P= 0.02)and nictrogen-corrected apparent metabolism energy(AMEn)(P= 0.03)than birds fed LE diets.It was concluded that LE+ PN showed a potential advantage to improve feed conversion and gut health of broilers,as well as economic profits.