One of the most important factors that determine feed utilization by chickens is the feed form. Although it is generally believed that pellet diets have a positive effect on chicken growth, there are some studies that have indicated no difference between pellet and mash on chickens performance. This study was conducted to assess the effects of feed form on production performance, egg quality, nutrient metabolism and intestinal morphology in two breed laying hens. Two hundred and sixteen 25-week-old Hy-Line brown (n = 108) and Hy-Line grey (n = 108) hens were selected. Each breed was randomly allocated into two treatments with 6 replications (9 birds in each replication), which were fed mash and pellet diets, respectively. Production performances were recorded daily and egg quality traits were measured every two weeks. At 42 weeks of age, one bird per replication from each experimental group was selected for metabolism determination and intestine morphology observation. Compared with mash diets, pellet diets improved laying rate (p < 0.05), ADFI (average daily feed intake, p < 0.05), egg weight, shell strength, yolk proportion and Haugh unit (p < 0.05) in both breeds and reduced the FCR (feed conversion ratio, p < 0.05) in Hy-Line grey. The apparent digestibility of DM% (dry matter) and CP% (crude protein) were significantly higher (p < 0.05) in both breed laying hens fed pellet than those fed mash. The apparent digestibility of P% (phosphorus) and Ca% (calcium) was higher in Hy-Line grey fed pellet and was higher in Hy-Line brown fed mash. Compared to mash diets, pellet diets increased the VH (villus height), CD (crypt depth) and VCR (ratio of villus height to crypt depth) of the small intestine of Hy-Line grey, and increased the VH and CD of duodenum and ileum of Hy-Line brown. Overall, pellet diets improved production performance and nutrition metabolism through positive changes in the laying rate, feed intake, egg albumen quality and apparent digestibility of laying hens. The current findings provided support for the advantages of feeding pellets during the peak egg laying period for the two popular laying hen strains, Hy-Line brown and Hy-Line grey.
Effects of essential oil/palygorskite composite on performance, egg quality, plasma biochemistry, oxidation status, immune response and intestinal morphology of laying hens
