Problem and its importance: Starter is the "heart" of the cheese making industry. only by proper handling of starter can good quality cheese be made. The economic loss from contaminated starter may prove disastrous to a cheese plant if proper corrective measures are not taken. Milk usually contains a variety of bacteria. Under plant conditions some of these bacteria get into the mother starter or bulk starter unless extreme caution is used. Comparatively little is known about how one organism influences another when grown in milk. This problem is important in the cheese industry. Purpose: The purpose of this research project is to determin the effect of some common contaminants on cheese starters. Some of the off flavors and slow acid production found in cheese making may be due to the results of contaminant organisms growing with the starter organisms. If this be true, more information on this subject will prove valuable. Some organisms have detrimental effects on milk. The question arises: What will two different organisms do when grown together in milk? Streptococcus lactis is important in the cheese industry because it satisfactorily produces the acid necessary in cheese making. If some organism inhibits or stimulates this acid production when grown with Streptococcus lactis, it is important that the cheesemaker know this. Scope: Only those contaminants commonly found in dairy products are considered in this project. Simulated plant conditions are used; that is, the starter being tested is contaminated one evening and the results checked and read the next day. Commercial lactic acid cheese starter from the Hansen's Laboratories and milk from the Utah State Agricultural College Creamery are used to propagate the starter. Different percentages of the contaminant are added to the starter to determine the effects of varying numbers of the contaminant on the starter organisms. A control starter is incubated and tested along with the contaminated starter. After the starters have been incubated at 70°F. Overnight, the following tests are run on each one: activity, acidity, pH, creatine, odor and appearance, and microscopic count. Starter vitality may be determined by the above tests; however, these do not indicate how the contaminant organisms affect cheese when carried on into the cheese making process. Therefore, this project is limited to the effects of contaminants on the starter and not on cheese. This latter problem is reserved for future investigators.

Conservation tillage production systems for flue-cured tobacco (Nicotiana tabacum L.) have been studied for many years. Inadequate chemical weed control and lack of acceptable pesticide and fertilizer application resulted in consistently lower yields and inferior cured leaf quality. The development of new conservation tillage equipment, improved methods of fertilizer application, and new herbicides, have resulted in a renewed interest in conservation tillage labeled for tobacco. This research investigated management practices to address slow early season growth characteristic of strip-tillage tobacco production. Objectives of the first study were to evaluate the methods of starter fertilizer application and determine the optimal rate. A transplant water treatment (11 kg ha⁻¹) and 3 rates (11, 22, and 45 kg ha⁻¹) of injected 9-45-15 (N:P₂O₅:K₂O) water soluble starter fertilizer were evaluated for early season plant growth and time of topping. Starter fertilizer treatments increased tobacco root weight by 22% and leaf area up to 41%. Earlier topping was observed as a result of starter fertilizer with 23 and 6% more plants topped during the initial topping date in 1999 and 2000, respectively. Starter fertilizer did not consistently increase the yield of either strip-tillage or conventional tillage tobacco. The objectives of the second study were to compare the use of raised beds with flat-planting and investigate cover crop residue management techniques. Residue management treatments minimized residue within the strip-tilled area with an early hooded spray application (strip-killed) of a burndown herbicide as opposed to the traditional broadcast burndown application. The use of raised beds for strip-tillage production of tobacco showed no clear benefit when compared to flat-planting. Strip-tillage plots were similar to conventional tillage for cured leaf quality and yield. Early season strip-kill burndown herbicide applications proved beneficial in reducing difficulties incorporating residue into the strip-tilled area thus improving the quality of the prepared seed bed. This research has added to the present knowledge regarding strip-tillage tobacco production, and refined necessary cultural practices. Transplant starter fertilizer is recommended to overcome the typical slow early season growth characteristic of strip-tilled tobacco. However, increased rates (greater than 11 kg ha⁻¹) or under-row injection of the material had no added benefit. The research also demonstrated that the use of raised beds should not be considered a necessary practice with the use of a strip-till implement that incorporates under-row subsoil tillage. This research has demonstrated that tobacco yields and quality comparable to conventional tillage can be realized using strip-tillage production techniques. / Master of Science

No description available.

No description available.

No description available.

Master of Science / Department of Agronomy / Dorivar Ruiz Diaz / Corn (Zea mays) response to fertilization and placement methods has been studied extensively; however studies on soybean [Glycine max (L.) Merr.] response to placement have been limited. Three studies were completed to evaluate different aspects of crop response. The objective of the first study was to evaluate the effect of starter and broadcast fertilizer application on corn and soybean, in a typical corn-soybean rotation in Kansas. Treatments were unfertilized control, starter (N, P and K), broadcast P and K using mono ammonium phosphate (MAP) and potassium chloride (KCl) and the combination of starter and broadcast. Corn and soybean yield generally was not affected by starter and broadcast treatments. Thus fertilization may be recommended only under specific conditions. The objectives of the second study were (i) to evaluate the effect of residual and direct fertilization on soybeans after corn under a corn-soybean rotation system, and (ii) study the effect of fertilizer P and K application on soil test P (STP) and soil test K (STK) changes over time. Direct fertilization increased soybean yield while residual fertilizer did not. Therefore maintenance rates may be effective to improve soybean yield and likely maintain STP and STK levels. Application of P and K fertilizer generated significant increases in STP and STK after one year of application. The rate of P and K fertilizer required to increase 1 mg kg-1 yr-1 was between 2.8 - 5.1 kg ha-1 for P and between 1.0- 2.5 kg ha-1 for K, respectively. The objective of the third study evaluate both corn and soybean response to direct P fertilization including starter and broadcast. The treatments were a control, two starter fertilizers (with N-P and N only), five P rates (9.8, 19.6, 29.3, 39.1, 48.9 kg P ha-1) and one treatment with starter fertilizer in addition to the broadcast fertilizer application. Corn grain yield was not significantly affected by any broadcast or starter treatments. Broadcast application rates significantly increased soybean yield on low STP levels. Results of this study show that large corn or soybean yield response to starter and broadcast P application are likely with low STP levels.

Master of Science / Department of Animal Sciences and Industry / R. Scott Beyer / Three experiments were conducted to evaluate the effects of gelatinized starch created during the pelleting process. Effects of gelatinization were first broadly tested to find if either increased or decreased gelatinization levels would increase broiler weight gain and feed efficiency during the starter period, 0 to 21 days of age. Results of the first experiment indicated a decrease (P<0.05) in broiler performance with increased levels of gelatinization, and a significant effect when the inclusion of gelatinized starch in the diet increased from 0 to 35%. A second experiment was conducted using a smaller range, 0 to 21% versus 0 to 35% inclusion of gelatinized starch in the diet and a smaller increment of increase, 3 versus 5%. Results of this experiment confirmed the results of the first experiment, and regression analysis was performed on the data. A linear decrease in body weight gain and quadratic increase in feed:gain (P<0.05) was observed as gelatinized starch was increased from 0 to 21% of the diet. A survey of the literature was conducted showing that most of the simulated levels of gelatinization were larger than those achieved with typical pelleted broiler diets. A third experiment was designed to investigate the levels of gelatinization observed in a pelleted diet and combined with three corn particle sizes, small (466 μm), medium (878 μm), and large (1240 μm), to find if any interactions existed. Chicks fed with the highest gelatinization level of 20%, (7.86% inclusion of pregelatinized starch) had lower body weight gains (P<0.05), and higher feed:gain (P<0.05) compared to chicks fed with 0% gelatinization. Small particle size had the lowest live body weight gain and lowest pen feed intake (P<0.05). There were no interactions found between gelatinization level and particle size (P>0.10). The results demonstrated a negative effect on chick body weight gain and feed efficiency by gelatinization of starch.

The effects of starter cultures on short- to medium-chain free fatty acid contents am sensory attributes of different batches of summer sausages were determined. The summer sausages were from range ram mutton, and formulated after grinding to contain 23% fat. Commercial starter cultures from different sources, including Micrococcus varians or Micrococcus species and Lactobacillus plantarum, commercial microbial lipase, an indigenous Micrococcus isolate or encapsulated lactic acid were used to prepare the summer sausages. Three batches were made, each batch receiving six different treatments. Three consumer panels evaluated the sausages for acceptability and a trained screened panel evaluated the products using the flavor profile test. Encapsulated lactic acid treatment significantly improved the sensory acceptability of the sausages. Presence of mutton flavor was not detected in indigenous Micrococcus isolate and L. plantarum treatment. Gas chromatography was used to quantify all short- to medium-chain fatty acids from the sausages. Common fatty acids, C6 through C12, were identified by retention data. Increased C6 and C8 levels due to addition of lipase were associated with increase in mutton and rancidity flavors of the product. The relationships among the level of major fatty acids and the sensory parameters were mostly negative.

Graduation date: 1994

Zugl.: Berlin, Techn. Univ., Diss., 2009