Effect of Formulation Density, Moisture, and Surfactant on Feed Manufacturing, Pellet Quality, and Broiler Performance

Transcription

1 2002 Poultry Science Association, Inc. Effect of Formulation Density, Moisture, and Surfactant on Feed Manufacturing, Pellet Quality, and Broiler Performance J. S. Moritz,* K. J. Wilson,* K. R. Cramer,* R. S. Beyer, 1, * L. J. McKinney, W. B. Cavalcanti, and X. Mo Department of Animal Science and Industry, Kansas State University, Manhattan, KS 66506; and Department of Grain Science and Industry Primary Audience: Feed Mill Managers, Nutritionists, Broiler Producers, Researchers SUMMARY Past research has illustrated that moisture addition to corn-soybean-based diets at the mixer can increase pellet durability and decrease pellet mill energy usage. Broiler feeding trials that used pelleted diets produced by the moisture addition process have illustrated that 3-to-6-wk feed efficiencies of male broilers can be significantly improved over diets manufactured without moisture. However, in these trials feed efficiency calculations were adjusted to account for variations in nutrient densities caused by moisture addition. Furthermore, variations in types of moisture additives were not explored. The current study determined the effects of different types of moisture additives (water/surfactant solution vs. water) and different formulation densities (NRC density vs. adjusted high density) on feed manufacturing, pellet quality, and 3-to-6-week male broiler performance. Control treatments, consisting of two diets with different nutrient densities without moisture additives, were also manufactured and fed. Adjusted high density broiler diets that included moisture were found to significantly increase pellet mill production rates compared to NRC control diets while maintaining similar pellet quality. Moreover, broilers fed these adjusted high density diets with moisture exhibited improved live weight gains above broilers fed diets formulated to NRC specifications with or without added moisture. Key words: broiler performance, feed manufacturing, moisture, nutrient density, pellet durability 2002 J. Appl. Poult. Res. 11: DESCRIPTION OF PROBLEM Broiler chickens are fed pelleted diets because these diets are easier to handle and result in improved bird performance [1]. Feed manufacturers strive to produce a high quality product with minimum production expense [2]. Fairchild and Greer [3] have demonstrated that increasing feed mash moisture at the mixer by 3% can increase pellet durability by 10% and decrease pellet mill energy usage by 2.3%, resulting in improved pellet quality and reduced milling expense. Research has shown positive relationships between pellet quality and broiler feed efficiency (FE) [4, 5]. Moritz et al. [6] reported 1 To whom correspondence should be addressed: jmoritz@oznet.ksu.edu and sbeyer@oznet.ksu.edu.

2 156 that increased pellet durability, gained through moisture additions to mash feed in the mixer, significantly increased 3-to-6-wk adjusted broiler FE [low moisture adjusted FE (0.515 g/ g) high moisture adjusted FE (0.529 g/g)]. The investigators adjusted FE to account for a nutrient dilution created by the addition of moisture. The objectives of the current study were to evaluate the addition of moisture to diets that were adjusted in nutrient content so as to be practical for feeding poultry and to examine different types of moisture additives. The use of a surfactant in moisture additives has been thought to facilitate the absorption of water into grain. However, research comparing the processing and nutritional effects of moisture additives with and without a surfactant has not been conducted. The impact of these processing methods was measured in terms of feed manufacturing efficiency, pellet quality, and 3- to-6-wk male broiler performance. MATERIALS AND METHODS Diet Compositions and Feed Manufacturing (Experiment 1) Experiment 1 consisted of manufacturing experimental broiler grower diets for use as feeding treatments in Experiment 2. Experimental grower diets consisted of two different nutrient-dense formulations arranged in a factorial structure with two different types of moisture additives. One formulation reflected National Research Council (NRC)-recommended values [7] for all nutrients prior to moisture addition. In a second formulation, all nutrients were increased 5% compared with the initial formulation, also prior to moisture addition. Each formulation had the same ingredient profile (Table 1). Moisture additions were made with either a commercial surfactant and water mixture or ordinary tap water. Two control grower diets were also manufactured, representing the two diets of different nutrient densities without any moisture additives. Moisture additions were made at the mixer [8] by using a commercial moisture application system [9]. Moisture was added to an inclusion of 5% of the diet. Immediately after moisture addition, the mash diets were mixed for 3 min followed by soybean oil addition and another JAPR: Research Report 3-min mix cycle. The mash was conveyed to the pellet mill and subsequently steam conditioned with a short-term conditioner [ m (1 3 ft) 10-s retention] set at a constant temperature of 82.2 C (180 F). Pellets were formed using a California Pellet Mill with a mm (5/ in.) die [10]. All diets were pelleted at the same pellet mill motor load. The six experimental grower diets were manufactured in four replicates, in a randomized complete block design. Blocking criterion was designated as time of manufacturing, and the experimental unit was one batch of feed (454 kg). Feed manufacturing was conducted over 2 consecutive d. During the manufacturing of each grower diet, measurements of pellet mill relative electrical energy usage [11], production rate [12], and hot pellet temperature [13] were collected. Immediately after each diet was manufactured, a representative sample of the run was collected and analyzed for bulk density [14], pellet durability [14], and percentage fines. These same samples were next analyzed for moisture [15] and starch gelatinization [16]. The samples were analyzed in duplicate, and averages were calculated, thus providing a mean for each replicate. All diets were bagged in kg (50 lb) allotments and stored for 1 wk before feeding. The six broiler grower diets were used as treatments for the second experiment. Broiler Performance (Experiment 2) In Experiment 2, commercial broilers were reared on the floor in a curtain-sided positivepressure ventilated house. Male, Cobb-Vantress, 1-d-old chicks were allotted to each floor pen [ m ( ft)], which was defined as the experimental unit. Pens contained fresh wood shavings, nipple drinkers, and a Choretime feed pan adapted to a hopper. All pens received the same mash starter diet for the first 3 wk. At the end of the third week, 45 birds were randomly assigned to each pen. From Weeks 3 through 6, each of the six grower diets were fed to 10 replicate pens (450 birds/ diet). Diets were randomly assigned to pens in each block, and blocks consisted of groupings of six pens within the house. At the conclusion of the sixth week, pen weights and feed con-

3 MORITZ ET AL.: MOISTURE ADDITIONS TO FEED 157 TABLE 1. Experimental grower diet compositions prior to moisture addition Ingredient NRC Formulation (%) Adjusted formulation (%) Yellow corn Soybean meal (47.5%) Meat and bone meal (47.9%) Soybean oil Limestone Salt Lysine Methionine Poultry premix A Defluorinated phosphate Monensin B BMD C Nitro D Calculated composition ME (kcal/kg) 3,143 3,300 Crude protein (%) Methionine (%) Lysine (%) Crude fat (%) Calcium (%) Available phosphorus (%) Analyzed composition Crude protein (%) Crude fat (%) A Supplied per kilogram of diet: manganese, 0.02%; zinc, 0.02%; iron, 0.01%; copper, %; iodine, %; selenium, %; folic acid, 0.69 mg; choline, 386 mg; riboflavin, 6.61 mg; biotin, 0.03 mg; vitamin B 6, 1.38 mg; niacin, mg; panthothenic acid, 6.61 mg; thiamine, 2.20 mg; menadione, 0.83 mg; vitamin B 12, 0.01 mg; vitamin E, IU; vitamin D 3, 2,133 ICU; vitamin A, 7,716 IU. B Monensin sodium 110 g/tonne inclusion (80 g/lb) (Elanco Animal Health, Indianapolis, IN). C Bacitracin methylene disalicylate 50 g/tonne inclusion (50 g/lb) Alpharma ( D Roxarsone 45.4 g/tonne inclusion (90 g/lb) (Alpharma). sumption were recorded, and live weight gains (LWG), feed intakes, FE, and mortality percentages were calculated for the 3-to-6-wk period. All FE values were calculated with mortality weights. Throughout the experiment, feed and water were provided ad libitum. All birds were reared according to protocols established by the Kansas State University Animal Care and Use Committee. The study was conducted during March and April. Throughout the experiments, temperature was regulated thermostatically by starting chicks at 35 C (95 F) and decreasing the temperature by 2.8 C (5 F) each subsequent week. During periods of high temperature when the 2.8 C(5 F) temperature decrease could not be achieved, the buildings curtains were opened, and fans were run to maximize bird comfort. Statistical Analyses Due to the treatment structures, two separate analyses were run for the feed manufacturing and broiler performance experiments. A formulation density type of moisture additive factorial analysis was run to explore the main effects and their interactions. A second analysis was then run, which included all six treatments. This analysis enabled comparisons to be made between the treatments and the two controls. Additionally, preplanned linear contrasts were performed to explore specific comparisons. All statistics were calculated with the GLM AN- OVA procedure of the Statistical Analysis System [17]. Significant effects were further explored using Fisher s least-significant difference test to determine differences among treatment means (α = 0.05).

4 158 RESULTS AND DISCUSSION Experiment 1 Table 2 describes the milling parameters and pellet qualities produced in Experiment 1. Treatments having adjusted formulation densities produced numerically higher rates of production as compared to formulations that were not adjusted, but differences were not significant (P = ). This finding may be the result of the high soybean oil content of the adjusted formulations that would aid in lubricating the pellet die. Thomas et al. [18] concluded that fat addition during pelleting improved pellet mill production due to the lubricating effect of added fat on the mash-die interface. In designing the experiment, a high oil formulation was necessary to increase the energy content of the adjusted formulation treatments without creating amino acid imbalances. Experimental treatments had the greatest impact on pellet quality (Table 2). Nutrient density of the formulations had an effect on pellet durability (P = ), modified pellet durability (P = ), and the percentage of fines (P = ). Adjusted formulation treatments produced pellets of significantly lower durabilities and higher percentages of fines as compared to NRC-formulated treatments. Moisture additive types had no significant effect on pellet quality (Table 2); however, when the experimental treatments pellet qualities were compared to their respective controls (Table 3), the use of either moisture additive significantly improved durabilities and decreased the percentage of fines. Although, only adjusted formulation treatments demonstrated a significant decrease in fines percentages (P = ). These findings are especially important with regards to the adjusted formulation treatments, which contained high percentages of soybean oil. Past research has shown that increasing fat above 2% in a corn-soybean broiler diet before pelleting will decrease pellet quality with respect to durability and the percentage of fines [19]. The current study demonstrates that adding fat at 6.5% prior to pelleting, in conjunction with added moisture, can produce pellets of 75% durability and less than 31% fines (Tables 1 and 2). JAPR: Research Report Pellet durability might have been improved in treatments containing moisture additives compared to control treatments because of significantly increased starch gelatinization (Table 3). Hoover defines starch gelatinization as an order-disorder phase transition that includes diffusion of water into a granule, hydration and swelling, uptake of heat, loss of crystallinity, and amylose leaching [20]. As gelatinized starch cools, the dispersed matrix forms a gel or paste-like mass, which may function as an adhesive or binding agent [21]. The presence of water is a prerequisite to initiate gelatinization and may be a limiting factor to fully gelatinize starch [18]. Lund [21] postulated that a water to starch ratio of 0.3:1 is required for gelatinization, and a ratio of 1.5:1 would be required for complete gelatinization. The data presented here support the theory of a graded relationship between starch gelatinization and moisture content (Table 3). It was also observed that gelatinization percentages were greater for diets of NRC density compared to adjusted density diets (P = , Table 2). This result may be due to the fatty adjuncts of soybean oil, which could complex with the amylose, consequently repressing swelling and solubilization [21]. The results of Experiment 1 show that the addition of 5% moisture, even if ordinary tap water, can increase pellet quality. The data also show significantly increased production rates (P = ) and pellet durabilities (P = ) as well as significantly decreased percentages of fines (P = ) when moisture additions of 5% were added to diet formulations of 5% higher nutrient density over NRC recommendations. Formulations of this type can be useful in solving problems associated with broiler grower diets that have high amounts of fat prior to pelleting. NRC formulations that incorporated moisture additions appeared to be superior in pellet quality; however, past research has shown that these diluted diets have a negative impact on broiler performance [6]. Relative electrical energy and production rates were not significantly affected due to treatment main effects or their interaction (Table 2). These findings were most likely a result of variability among experimental pelleting runs. Precise control among pel-

5 MORITZ ET AL.: MOISTURE ADDITIONS TO FEED 159 TABLE 2. Influence of moisture type and formulation density on milling parameters and pellet quality (Experiment 1) Production PDI A Modified PDI B Peak gel Starch Bulk density REE E Fines HPT F rate PMC G (%) (%) temperature C ( C) gel D (%) (kg/m 3 ) (kwh/mt) (%) ( C) (MT/h) (%) NRC + surfactant and water a a ab ab NRC + water a a a a Adjusted + surfactant and water ab b bc b Adjusted + water b ab c b LSD H Probability Main effects and interactions Moisture type Formulation density Interaction a,b Means within a column with no common superscript differ significantly (P < 0.05). A Pellet durability index. B Modified pellet durability index (using five 13-mm hex nuts for added pressure on pellets). C Peak temperature of starch gelatinization determined by differential scanning calorimetry (DSC). D Starch gelatinization determined by DSC and calculated on a dry matter basis. E Relative electrical energy of the pellet mill (kilowatt hour/tonne); MT = tonne. F Hot pellet temperature. G Pellet moisture content. H Fisher s least significant difference value.

6 160 JAPR: Research Report TABLE 3. Treatment effects on milling parameters and pellet quality (Experiment 1) Peak gel Bulk Production PDI A Modified PDI B temperature C Starch density REE E Fines HPT F rate PMC G (%) (%) ( C) gel D (%) (kg/m 3 ) (kwh/mt) (%) ( C) (MT/h) (%) NRC + surfactant and water a a ab ab c ab NRC + water a a b a bc a Adjusted + surfactant and water b b b c b c Adjusted + water b b a cd bc bc NRC (no added moisture) b b b bc bc d Adjusted (no added moisture) c c a 5.52 d a e LSD H Probability Comparisons of all treatments Linear contrast P-values NRC vs. NRC moisture treatments Adjusted vs. adjusted moisture treatments NRC vs. adjusted moisture treatments a e Means within a column with no common superscript differ significantly (P < 0.05). A Pellet durability index. B Modified pellet durability index (using five 13-mm hex nuts for added pressure on pellets). C Peak temperature of starch gelatinization determined by differential scanning calorimetry (DSC). D Starch gelatinization determined by DSC and calculated on a dry matter basis. E Relative electrical energy of the pellet mill (kilowatt hour/tonne); MT = tonne. F Hot pellet temperature. G Pellet moisture content. H Fisher s least-significant difference value.

7 MORITZ ET AL.: MOISTURE ADDITIONS TO FEED 161 TABLE 4. Influence of moisture type and formulation density on broiler performance, 3-to-6-wk data (Experiment 2) Live wt Feed intake Feed efficiency A Mortality gain (g) (pen) (kg) (g/g) (%) NRC + surfactant and water 1,604 b ab b 2.89 NRC + water 1,606 b a b 2.67 Adjusted + surfactant and water 1,643 a b a 2.44 Adjusted + water 1,650 a b a 1.56 LSD B Probability Main effects and interactions Moisture type Formulation density Interaction a,b Means within a column with no common superscript differ significantly (P < 0.05). A Body weight gain/feed consumption. B Fisher s least-significant difference value. leting runs was difficult due to differences in ambient temperature and downtime between runs. Pellet manufacturing was further complicated due to the use of 454-kg (1,000 lb) batches of feed, which required a finite time to reach pellet mill steady-state conditions. Experiment 2 Experiment 2 focused on bird performance at 3 to 6 wk to corroborate past research that found significant moisture addition effects on broiler performance during this same period [6]. Table 4 illustrates the performance data collected during the 3-to-6-wk period. Nutrient density was the predominate reason for any differences in performance. Live weight gain was greater for adjusted high-density formulation treatments compared to NRC formulation treatments (P = ). This effect was probably a result of a nutrient dilution effect in NRC diets, created by moisture addition. This finding was similar to results found in a previous study on moisture addition [6]. The adjusted formulation treatments in the current study were originated to counteract this dilution effect. Broilers fed diets of adjusted density that included moisture gained more weight than any other experimental treatment or control (P = , Table 5). This discovery was most likely an additive effect of moisture addition and the high nutrient density formulation (Tables 4 and 5). The adjusted density compensated for potential nutrient dilution effects, whereas added moisture increased pellet durability (P = ) and decreased the percentage of fines (P = , Table 3). Broilers fed higher quality pellets may improve their performance due to increases in productive energy and decreased feed wastage [4, 5, 6, 22]. Nutrient density also affected feed intakes (P = ) and FE (P = ); however, type of moisture additive had no significant effect (Table 4). Broilers fed NRC-formulated diets that incorporated moisture additives ate significantly more feed and had significantly lower FE than broilers fed adjusted diets containing moisture additives (Table 4). These findings could be attributed to the nutrient dilution effect of the NRC formulated diets, which would require the broilers to eat more of the diluted feed to meet their energy requirements. Additionally, the high crude fat percentages contained in the adjusted diets (Table 1) could have contributed to more efficiently produced fat tissue. FE was less for diets with moisture additives respective to each control diet (Table 5). It should be noted, however, that broilers fed adjusted-density control diets consumed less feed than any other treatment, which resulted in the lowest numerical weight gain. The current FE data differed from the previous moisture study [6], in which moisture additions resulted in increased adjusted FE. A possible explanation for this contrast could be that the current study was conducted in March and April, with ideal broiler-rearing outside temper-

8 162 JAPR: Research Report TABLE 5. Treatment effects on broiler performance, 3-to-6-wk data (Experiment 2) Live wt Feed intake Feed efficiency A Mortality gain (g) (pen) (kg) (g/g) (%) NRC + surfactant and water 1,604 b ab c 2.89 NRC + water 1,606 b a c 2.67 Adjusted + surfactant and water 1,643 a bc b 2.44 Adjusted + water 1,650 a bc b 1.56 NRC (no added moisture) 1,610 b c b 2.67 Adjusted (no added moisture) 1,585 b d a 2.89 LSD B Probability Comparisons of all treatments Linear contrasts NRC vs. NRC moisture treatments Adjusted vs. adjusted moisture treatments NRC vs. adjusted moisture treatments a d Means within a column with no common superscript differ significantly (P < 0.05). A Body weight gain/feed consumption). B Fisher s least significant difference value. atures; whereas broilers in the previous study were reared during the much colder months of November and December. Ideal outside environmental temperatures could lessen the need for broiler maintenance energy. Nir et al. [4] define productive energy as net feed energy less bird maintenance energy. Although improved pellet quality would be expected to increase productive energy, this energy gain could be in excess relative to low-maintenance energy requirements, as well as the fixed protein content of the diet. Other research has also illustrated that broilers raised from 3 wk to market- ing during favorable outside environmental temperatures demonstrated decreased FE despite improved pellet quality [23]. Mortality percentages were not affected by either type of moisture additive (P = ) or by variation in nutrient density (P = ). Additionally, control treatment mortalities did not differ from any mortality results of any experimental treatment. Adjusted density broiler grower diets that include moisture additives of either type before conditioning and pelleting may improve 3-to-6-wk performance without affecting broiler survivability. CONCLUSIONS AND APPLICATIONS 1. Adding moisture to an adjusted density corn-soybean-based broiler diet may significantly increase pellet mill production rates while maintaining statistically similar pellet durabilities and fine percentages respective to typical corn-soybean based NRC diets without added moisture. 2. Increasing the water to starch ratio prior to pelleting significantly improved starch gelatinization, which may aid in creating a more durable pellet. 3. Problems of poor pellet quality associated with diet formulations that incorporate high amounts of oil may be resolved through the addition of moisture to pre-processed mash. 4. Adding ordinary tap water in the mixer to an adjusted-density corn-soybean-based mash diet and subsequently pelleting the diet may result in significant increases in broiler LWG in the 3- to-6-wk grower period. 5. Future studies should expand upon the idea of adding moisture to broiler diets by exploring the effects of graded levels of moisture addition and formulation adjustment on milling parameters, pellet quality, and bird performance.

9 MORITZ ET AL.: MOISTURE ADDITIONS TO FEED 163 REFERENCES AND NOTES 1. Briggs, J. L., D. E. Maier, B. A. Watkins, and K. C. Behnke Effect of ingredients and processing parameters on pellet quality. Poult. Sci. 78: Mommer, R. P., and D. K. Ballantyne Reasons for pelleting. Pages 3 6 in A Guide To Feed Pelleting Technology. Hess and Clark, Inc., Ashland, OH. 3. Fairchild, F., and D. Greer Pelleting with precise mixer moisture control. Feed Int. 20(8): Nir, I., Y. Twina, E. Grossman, and Z. Nitsan Quantitative effects of pelleting on performance, gastrointestinal tract and behavior of meat-type chickens. Br. Poult. Sci. 35: Moran, E. T., Jr Effect of pellet quality on the performance of meat birds. Pages in Recent Advances in Animal Nutrition. W. Haresign and D.J.A. Cole, ed. Butterworths, London. 6. Moritz, J. S., R. S. Beyer, K. J. Wilson, K. R. Cramer, L. J. McKinney, and F. J. Fairchild Effect of moisture addition at the mixer to a corn-soybean based diet on broiler performance. J. Appl. Poult. Res. 10: National Research Council Nutrient Requirements of Poultry. 9th rev. ed. Natl. Acad. Press, Washington, DC. 8a. Sprout Waldron Model B-37, double ribbon mixer with a shaft speed of 34 rotations per minute and a capacity of 454 kg (1,000 lb). Sprout-Waldron Manufacturing Engineers, Muncy, PA. 9. Agrichem, Inc., Ham Lake, MN. 10a. California Pellet Mill Master Model HD Series CPM Co., Crawfordsville, IN. 11. Relative electrical energy was measured specifically on the pellet mill (Amprobe Instrument model DMI, Core Ind., Inc., Lynbrook, NY). 12. Production rate was calculated by dividing tonnes of pellets produced by total production time in hours. 13. Hot pellet temperature was taken on a sample of pellets collected directly after pellets were purged from the die. 14. American Society of Agricultural Engineers ASAE S269.4, Cubes, Pellets, and Crumbles Definitions and Methods for Determining Density, Durability, and Moisture. Standards Am. Soc. Agric. Eng., St. Joseph, MI. Due to the use of a 5/ in. die, pellets were sifted in a No. 6 American Society for Testing and Materials (ASTM) screen. Five hundred grams of sifted pellets was placed in a dust-tight enclosure and tumbled for 10 min at 50 rotations per minute. The enclosure was of the following dimensions: in., with a 2-9-in. plate affixed diagonally along one of the in. sides. The tumbled samples were then sifted again [No. 6 (ASTM)] and weighed. The pellet durability index was calculated by dividing the weight of pellets after tumbling by the weight of pellets before tumbling then multiplying by 100. The modified pellet durability index was determined in a similar manner with the exception of adding five 13- mm hex nuts to the pretumbled sample in order to obtain added pellet pressure. 15. American Association of Cereal Chemists Moisture Air-Oven Method. AACC Method 44-15A. Approved Methods of the American Association of Analytical Chemists Vol II. Am. Assoc. Anal. Chem., St. Paul, MN. 16. Starch gelatinization was determined through differential scanning calorimetry (DSC) (DSC7, Perkin-Elmer, Norwalk, CT) and calculated on a dry matter basis. Enthalpy values were determined by a computer integrator for peaks in the approximate temperature range for cornstarch. The percentage of starch gelatinization was determined by subtracting the enthalpy of the unprocessed mash sample from the enthalpy of processed pellet sample and dividing the difference by the enthalpy of the unprocessed mash sample. The method used for this analysis included: holding the sample for 1 min at 30 C, then heating from 30 to 130 C by10 C per min. 17. SAS Institute The SAS System for Windows Release 8.1. SAS Institute Inc., Cary, NC. 18. Thomas, M., T. van Vliet, and A. F. B. van der Poel Physical quality of pelleted animal feed 3. Contribution of feedstuff components. Anim. Feed Sci. Technol. 70: Richardson, W., and E.J. Day Effect of varying levels of added fat in broiler diets on pellet quality. Feedstuffs (May 17): Hoover, R Starch retrogradation. Food Rev. Int. 11: Lund, D Influence of time, temperature, moisture, ingredients and processing conditions on starch gelatinization. CRC Crit. Rev. Food Sci. Nutr. 20: Jensen, L. S., L. H. Merill, C. V. Reddy, and J. McGinnis Observations on eating patterns and rate of food passage of birds fed pelleted and unpelleted diets. Poult. Sci. 41: Acar, N., E. T. Moran, Jr., W. H. Revington, and S. F. Bilgili Effect of improved pellet quality from using a calcium lignosulfonate binder on performance and carcass yield of broilers reared under different marketing schemes. Poult. Sci. 70: Acknowledgments This study was financed part by state and Hatch funds allocated to Kansas State University and by Agrichem Inc. The authors acknowledge Myron Lawson and Robert Resser for their assistance with animal husbandry. Contribution No J from the Kansas Agricultural Experiment Station.