STIMULATION OF IGG ANTIBODY RESPONSE IN VITRO BY T CELL-REPLACING FACTOR

A soluble factor (TRF) produced by mixtures of allogeneic mouse spleen, lymph node, and thymus cells functionally replaces T cells in a primary IgM antibody response to sheep blood cells in vitro. It is now shown that TRF can also reconstitute an IgG antibody response in T cell-deprived spleen cultures derived from preimmunized mice. The optimal time of addition and the amount of TRF required differ between primary and secondary in vitro systems

The Effects of Medium Chain Fatty Acids in Mash and Crumbled Pellet Diets on Growth Performance of Broilers

The objective of this experiment was to determine the effects of medium chain fatty acids (MCFA) in mash and crumbled pellet broiler diets. A total of 400 male chicks (Cobb 500; initial BW 0.092 lb) were housed in 4 Petersime batteries and used in an 18-d study. Treatments were randomly assigned to 80 cages within location block resulting in 8 cages per treatment with 5 chicks per cage at placement. Treatments were arranged in a 2 × 5 factorial with main effects of feed type (mash and crumbled pellet) and 0.5% MCFA inclusion (no inclusion, control; hexanoic acid, C6; octanoic acid, C8; decanoic acid, C10; and dodecanoic acid, C12). Fat inclusions in the diets were equalized using 0.5% soybean oil in the control diet. Prior to crumbling, diets were conditioned at 185°F for approximately 20 s and pelleted (CPM, model CL-5, Crawfordsville, IN) with a 5/32 × 7/8 in. ring die. Dietary treatments were fed for the full duration of the study. There was no evidence of feed form × MCFA interactions. From d 0 to 18, chicks fed pelleted diets had improved (P \u3c 0.001) body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR), and final BW compared to those fed mash diets. For the overall treatment period, there was no evidence of a MCFA effect (P \u3e 0.10) on broiler performance. Pelleting and crumbling feed improved growth performance regardless of MCFA inclusion. The MCFA inclusion did not positively influence growth performance of broilers

Decreasing Corn Particle Size Increases Metabolizable Energy When Fed to Gestating Sows

Previous research has demonstrated that reducing the particle size of corn improved metabolizable energy (ME) utilization in many phases of swine production. One phase that has had limited research thus far is the gestating phase for sows. The objectives of this paper were to determine the effects of corn particle size on the digestibility of gross energy (GE), and determine the digestible energy (DE) and ME in gestating sow diets. A total of 27 sows during the second phase of gestation (d 40 to 74) were chosen and fed a common diet with corn ground to 1 of 3 target average particle sizes (geometric mean diameter; dgw) of 400, 800, or 1200 μm. Corn was ground using a 3 high roller mill (RMS model 924). Titanium dioxide (0.25%) was included in the diet as an indigestible marker for index digestibility calculations. Sows were fed experimental diets for 7 d to allow for diet adaptation before a 2-d collection period. At the beginning of the collection period, sows were fitted with a urinary catheter and urine was collected in buckets containing 20 mL of sulfuric acid. Fecal grab samples were also collected from each sow during the collection period. Subsamples were taken, mixed, analyzed for GE, and titanium levels to determine digestibility of gross energy and to calculate DE and ME. The ME of corn was calculated by subtracting the ME of soybean meal (1,494 kcal/lb) and soybean oil (3,889 kcal/lb) from diet ME, utilizing the NRC 2012 values for those ingredients. Apparent total tract digestibility (ATTD) of GE and calculated DE, ME, and corn ME content increased (linear, P \u3c 0.001) as corn particle size was reduced from 1200 to 400 μm. The ME of the diet (88.5% DM) increased by 81 kcal/lb as the dgw was reduced from 1,200 to 400 μm. The calculated corn ME (88.5% DM) also increased by 103 kcal/lb as the dgw was reduced from 1,200 to 400 μm. Utilizing a linear regression model and the analyzed corn particle size data herein, it was determined that for every 100 μm reduction in corn dgw from 1,372 to 404 μm, the ME value of corn is increased by 10.7 kcal/lb

The Effects of Filter Type and Warm-Up Time on Pellet Durability Index Using the Holmen NHP100 Portable Pellet Tester

The Holmen NHP100 (TekPro Ltd, Norfolk, UK) is a portable forced air pellet tester commonly used by the feed industry to determine the pellet durability index (PDI). The objective of this study was to determine the effect of filter type and machine warm-up time on PDI. A corn-soybean meal-based grower diet was conditioned at 185°F for 30 sec and subsequently pelleted using a laboratory pellet mill (Model CL5 California Pellet Mill Co., Crawfordsville, IN) equipped with a 0.16- × 0.5-in die. Production rate was 120 lb/h. Once cool, pellets were analyzed for PDI using the NHP100 with a 60-sec run time. Air temperature and pressure within the NHP100 were recorded throughout the experiment. Treatments were arranged in a 3 × 8 factorial with varying filters (none, factory tissue filter, or commercial paper towel filter) and machine warm-up time (0, 3, 6, 9, 12, 15, 18, or 21 min). There were three replicates per treatment. Pellets were sifted before and after analysis for separation of fines and pellets using a U.S. #6 standard sieve. There was a filter × warm-up time interaction (P ≤ 0.05) for air temperature. The air temperature without warm-up time (0 min) was greater with the factory filter and paper towel compared to no filter. Air temperature remained similar regardless of filter type as the warm-up time increased from 6 to 21 min There was a filter × warm-up time interaction (P ≤ 0.05) for air pressure. At 0 min warm-up time, there were no differences in air pressure between none, factory and paper towel filters. At 3 to 21 min warm-up time, air pressure remained similar between factory and paper towel filters, while no filter was greater than the paper towel filter. There was a filter × warm-up time interaction (P ≤ 0.05) for PDI. For no filter, increasing warm-up time from 0 to 6 min increased PDI with no further increase from 6 to 21 min. However, there were no differences in PDI with increasing warm-up time when using the factory filter or paper towel. Using the factory filter or paper towel had similar PDI, but resulted in greater PDI compared to no filter. In conclusion, warm-up time did not influence air temperature, pressure, or PDI when using a filter. Therefore, it is suggested to use a filter when conducting PDI analysis using the Holmen NHP 100

The Effect of Screen Hole Diameter and Hammer Tip Speed on the Subsequent Particle Size of Ground Corn Analyzed With and Without Sieving Agent

Reducing the particle size of grains increases the ratio of surface area to volume which provides digestive enzymes greater access to nutrients, therefore improving utilization of the feed. Hammermills are a very cost-effective method of reducing grains to very fine particle sizes for feeding. A variety of settings can be changed on hammermills to achieve a target particle size. Thus, the objective of this experiment was to determine the effects of screen hole diameter, hammer tip speed, and the inclusion of a sieving agent on the particle size of corn. Treatments were arranged in a 4 × 6 × 2 factorial with screen hole diameter (10/64, 12/64, 16/64, 24/64 in.), hammer tip speed (20,500, 18,450, 16,400, 14,350, 12,300, and 10,250 ft/min), and particle size analytical method (with and without sieving agent). All treatments were ground using a Bliss Hammermill (Model 22115) equipped with a variable frequency drive (VFD) and a 25 HP motor. The screen hole diameter and hammer tip speed were randomized to reduce the effects of grinding and sampling order. There were 3 replicates per treatment. Samples were analyzed for geometric mean diameter (dgw) and standard deviation (Sgw) of the particle size. There was no evidence of a screen hole diameter × hammer tip speed × sieving agent interaction for all variables (P \u3e 0.327). There was a linear screen hole diameter × linear hammer tip speed interaction (P \u3c 0.001) for dgw. When increasing tip speed from 10,250 to 20,500 ft/min, the rate of decrease in dgw was greater as screen hole diameter increased from 10/64 to 24/64. There was a quadratic screen hole diameter × linear hammer tip speed interaction (P \u3c 0.035) for Sgw. When increasing the screen size from 10/64 to 24/64, the rate of increase in Sgw was greater as tip speed increased from 10,250 to 16,400 ft/min and was similar from 16,400 to 20,500 ft/min. There was no evidence of a screen hole diameter × hammer tip speed interaction for percent fines (P \u3e 0.153). There was no evidence of a screen hole diameter × sieving agent or hammer tip speed × sieving agent interaction for dgw or Sgw (P \u3e 0.540). There was a linear screen hole diameter × sieving agent interaction (P \u3c 0.001) for percent fines. When increasing the screen size from 10/64 to 24/64, the rate of decrease in percent of fine particles was greater when sieving agent was used compared to when it wasn’t used. The results of this trial indicate that the particle size range for a specified hammermill screen size can be altered by adjusting the hammer tip speed with a VFD. Additionally, particle size should be determined with the addition of sieving agent during analysis to more accurately characterize the particle size distribution, especially of finer particles that may influence flowability or animal intake

Decreasing Corn Particle Size Increases Metabolizable Energy When Fed to Gestating Sows

Previous research has demonstrated that reducing the particle size of corn improved metabolizable energy (ME) utilization in many phases of swine production. One phase that has had limited research thus far is the gestating phase for sows. The objectives of this paper were to determine the effects of corn particle size on the digestibility of gross energy (GE), and determine the digestible energy (DE) and ME in gestating sow diets. A total of 27 sows during the second phase of gestation (d 40 to 74) were chosen and fed a common diet with corn ground to 1 of 3 target average particle sizes (geometric mean diameter; dgw) of 400, 800, or 1200 μm. Corn was ground using a 3 high roller mill (RMS model 924). Titanium dioxide (0.25%) was included in the diet as an indigestible marker for index digestibility calculations. Sows were fed experimental diets for 7 d to allow for diet adaptation before a 2-d collection period. At the beginning of the collection period, sows were fitted with a urinary catheter and urine was collected in buckets containing 20 mL of sulfuric acid. Fecal grab samples were also collected from each sow during the collection period. Subsamples were taken, mixed, analyzed for GE, and titanium levels to determine digestibility of gross energy and to calculate DE and ME. The ME of corn was calculated by subtracting the ME of soybean meal (1,494 kcal/lb) and soybean oil (3,889 kcal/lb) from diet ME, utilizing the NRC 2012 values for those ingredients. Apparent total tract digestibility (ATTD) of GE and calculated DE, ME, and corn ME content increased (linear, P \u3c 0.001) as corn particle size was reduced from 1200 to 400 μm. The ME of the diet (88.5% DM) increased by 81 kcal/lb as the dgw was reduced from 1,200 to 400 μm. The calculated corn ME (88.5% DM) also increased by 103 kcal/lb as the dgw was reduced from 1,200 to 400 μm. Utilizing a linear regression model and the analyzed corn particle size data herein, it was determined that for every 100 μm reduction in corn dgw from 1,372 to 404 μm, the ME value of corn is increased by 10.7 kcal/lb

The Effects of Coarse Corn Inclusion in Broiler Diets on Pellet Quality

Previous research has demonstrated the benefits of including large grain particle size in poultry diets on gizzard and gastrointestinal tract development. However, including these larger particles may decrease pellet integrity. Therefore, the objective of this study was to evaluate the effect of coarse corn inclusion level on pellet quality. A corn soybean meal-based finisher broiler diet with 1.5% mixer added fat was used in this experiment. Treatments were created by replacing 600 μm corn with 1,200 μm coarse rolled corn at 0, 10, 20, or 30% of the diet. Mash treatments were pelleted using a 30-horsepower pellet mill (Model 1012-2 HD, California Pellet Mill) equipped with a 3/16 × 1 ¼ in. die. Pelleting order was randomized within each replicate with 3 replicates per treatment. Target conditioning temperature was 185°F for 30 s retention time at a 34 lb/min production rate. Samples were analyzed for hot pellet temperature (HPT), fine to pellet ratio (%fines) and pellet durability index (PDI) using the standard tumble box (STD) and Holmen NHP100 (NHP) for 60 s. Data were analyzed using the GLIMMIX procedure of SAS. There were no differences among analyzed variables as the inclusion level of coarse corn was increased (P \u3e 0.05). The %fines and PDI remained similar across treatments, regardless of method. In conclusion, increasing the concentration of coarse corn from 0 to 30% did not influence PDI