Impact of particle size, thermal processing, fat inclusion, and moisture addition on starch gelatinization of broiler feeds

Thermal processing of corn and physical form of broiler diets

This study aimed to assess the effect of preprocessing of corn and of physical form of diets on growth performance, carcass yield, and nutrient digestibility in broilers and also the influence of corn processing on pellet quality. A total of 1,080 male Cobb chicks from 1 to 35 D were evaluated. Birds were distributed according to a completely randomized design in a 3 × 2 factorial arrangement, with 3 types of corn processing (unprocessed, pelleted, or expanded), and 2 diet physical forms (mash or pelleted), totaling 6 treatments and 9 replicates with 20 birds. The data were submitted to ANOVA, and means were compared by Tukey's test (P < 0.05). There was no interaction between the physical form and preprocessing of corn for any of the studied variables (P > 0.05). The use of expanded corn in the diets before pelleting resulted in higher pellet durability index and lower amount of fines (P < 0.05) when compared with unprocessed corn. Broilers fed pelleted diets had higher feed intake (FI) and weight gain (WG; P < 0.001), higher amounts of abdominal fat (P < 0.05), and lower ileal digestible energy (IDE, P = 0.05) than those fed mash. There was no effect of the feed form on nutrient digestibility (P > 0.05). Broilers fed diets with unprocessed corn had higher FI when compared to those fed diets with expanded or pelleted corn (P < 0.001). The use of pelleted corn resulted in lower WG than the other processing methods (P < 0.01). The corn expansion process improved feed conversion ratio and adjusted feed conversion ratio (P < 0.001). Inclusion of expanded corn improved the coefficient of apparent ileal digestibility of DM, CP, starch, and IDE (P < 0.05) in comparison with unprocessed corn. It is concluded that pelleted diets improve broiler performance. The corn expansion can be used to improve physical quality of the diets and broilers growth performance and nutrient digestibility.

Feeding Complete Concentrate Pellets Containing Ground Grains or Blend of Steam-Flaked Grains and Other Concentrate Ingredients in Ruminant Nutrition – A Review

The feed industry has attempted to encourage the animal husbandry sector to feed complete concentrate pellets containing ground grains in ruminant nutrition and thus prevent farmers from making concentrate in their farms. Reducing particle size using pre-pelleting grinding and pressing materials during pellet formation, plus starch gelatinization by heat treatment in the conditioner are key factors determining the extent and rate of starch digestion in ingested pellets. If prepelleting grinding of corn and barley grain for using in the pelleted concentrate results in ground materials of less than 1.8 mm mean particle size (especially in the case of barley grain which is highly fermentable), then it increases the rate of fermentability in the rumen which in turn increases the acidosis risk. Such situation and dissatisfaction from pellets feeding to ruminant have directed farmers to produce homemade mash concentrate which may include steam-flaked form of grains in the concentrate mixture. Pelleting process increases the time needed to collapse the pellet in the rumen so delays the access of microbes to fermentable organic matter. This counterbalance property highly depends on pellet size with highest effect obtained using 10 mm diameter pellets for cattle. Feeding separately steam-flaked grains (plus other pelleted/mash non-grain ingredients of concentrate) may give results similar to the complete concentrate pellets having ground grains prepared according to optimized recommendations (pellet diameter and grain mean particle size). Nonetheless cost benefit studies are necessary to adopt one of the above two optimized technologies that has higher starch utilization and lower fecal starch excretion by animal. In the situation where consuming steam-flaked grains has priority of application in the diet, it is strongly recommended to pellet non-grain portions of concentrate for obtaining numerous pellet advantages such as reducing transportation cost, dust, sorting and bird removal.

Effect of different types and levels of fat addition and pellet binders on physical pellet quality of broiler feeds

Two experiments were conducted to evaluate the effects of different types and levels of mixer-added fat (soybean oil: SO and calcium fat powder: CFP) and pellet binders (PBs: calcium lignosulfonate (CaLS) and bentonite (Ben)) on physical pellet quality (PPQ) parameters. PPQ included pellet durability index (PDI), pellet hardness, and pellet length of broiler diets processed under short-term conditioning. The first experiment had 4 treatments arranged as a 2 × 2 factorial with 2 types (SO and CFP) and 2 levels (1.5 and 3%) of mixer-added fat. In the second experiment, 22 treatments, combinations of 2 types of mixer-added fat (SO and CFP) at 3 levels (0, 1.5 and 3%) and 2 types of PB (CaLS = 0, 0.5, and 1% and Ben = 0, 1, and 2%), were arranged by a completely randomized design. PDI was measured by 2 devices: Pfost Tumbling box (PDIT) and Holmen NHP tester (PDIH). The results showed that the diets containing 1.5% CFP without PB had significant differences in all PPQ parameters. The results revealed that adding 0.5% CaLS to the 3% SO diets significantly enhanced PDIH, pellet hardness, and pellet length compared to other treatments. Moreover, 1.5% CFP diets with 2% Ben had significantly higher PDIT, PDIH, and pellet hardness among the treatments. Based on contour plots, different levels of Ben in the diets containing SO failed to create optimum PDIT values (>96%). However, 1.5 to 2.50% CFP diets without Ben had the optimum PDIT values. The optimum PDIT value was achieved by the diets containing 3% SO in the range of 0.21 to 0.56% CaLS. Furthermore, adding 0.5% CaLS to the diets containing less than 2.86% SO resulted in suboptimal PDIT values (<96%). The diets containing 1.5 to 2.50% CFP without CaLS had the optimum PDIT values. However, increasing CaLS levels more than 0.38% led to suboptimal PDIT values. Overall, these results indicated that the selection of appropriate PBs should be based on type and level of mixer-added fat.