Effect of Enogen^® Feed Corn on Pelleting Characteristics of a Poultry Diet and Subsequent Broiler Growth Performance and Carcass Traits^*

MATERIALS AND METHODS

This research was conducted according to the experimental protocols approved by the Institutional Animal Care and Use Committee at Kansas State University.

Twelve hundred male broiler chicks (Cobb-Vantress, Siloam Springs, AR) were used in a 45-d randomized complete block experiment with treatments arranged as a 2×2 factorial, with factors consisting of corn source [conventional (CON) and EFC] and conditioner retention time (30 and 80 sec). Corn was ground to 700 μm in the starter phase and 900 μm in the grower and finisher phases using a hammermill (Bliss, Model 22115). Starter, grower and finisher broiler diets were mixed in a 907 kg Hayes and Stolz horizontal counterpoise mixer (Table 1). For treatments containing EFC, conventional corn was replaced by EFC on a kg:kg basis.

For the pelleting trial, diets were steam conditioned (Wenger twin staff pre-conditioner, Model 150) for 30 or 80 sec at 75°C and subsequently pelleted using a 30-horsepower pellet mill (1012-2 HD Master Model, California Pellet Mill) equipped with a 4-32 mm pellet die. Production rate was set at 10 kg per min, approximately 65% of the rated throughput for the pellet mill. Pelleting of the starter, grower and finisher diets provided three replications for each treatment; therefore, diet served as the blocking factor. Conditioner retention times were calculated by adjusting the conditioner screw speed and dividing the amount of feed in the conditioner by the production rate. For each run, a conventional corn-soybean meal flush diet was used to warm the mill up to 75°C, the first treatment was pelleted and the mill was shut down to allow the pelleted feed to cool and to adjust conditioner screw settings for the next treatment. Conditioning temperature, hot pellet temperature (HPT) and production rate were recorded at 3 time points during each run (Table 2). Pellet mill amps and volts were also monitored throughout each run to calculate energy consumption.

Prior to pelleting, a total of 10 mash samples per treatment were collected for analysis of soluble starch. During each processing run, 3 conditioned mash and 3 pellet samples were collected throughout the run. Conditioned mash samples were immediately analyzed for soluble starch and pellets were immediately placed in an experimental counter-flow cooler for 10 min. Once pellets were cool, they were analyzed for soluble starch and pellet durability index (PDI).

For the performance trial, chicks were maintained on a 24 h lighting schedule in a thermostatically controlled room with ad libitum access to feed and water. Chicks were housed in 1.2×2.4 m floor pens with 7-10 cm of pine shavings. Each pen was fitted with single hanging feeder and 4 nipple waterers. Chicks were randomly allocated to groups of 15, weighed and randomly assigned to 1 of 80 floor pens. Treatments were randomly assigned to pens and blocked by location for a total of 20 replications per treatment. Chicks were fed a common diet from 0-4 days of age before initiation of the experiment. Therefore, day 0 of the experiment corresponded with 5 days of age for the chicks. A starter diet was fed from study day 0-10, a grower diet from day 11-24 and a finisher diet from day 25-45. In the case of mortality, chick weight, feeder weight, treatment and pen number were recorded. Pen weights and feed consumption were measured on day 11, 25, 39 and 45 for calculation of body weight gain, feed intake and feed efficiency (Table 3). Additionally, half of the chicks from each treatment were harvested on day 39 and the remaining half were harvested on day 45 for determination of carcass weight and dressing percentage (Table 4). Data were analyzed using the GLIMMIX procedure in SAS 9.4 with pen as the experimental unit and pen location as the blocking factor. Main effects included corn type and conditioner retention time. Results were considered significant if p≤0.05 and were considered marginally significant between p>0.05 and p≤0.10.