Lactobacillus delbrueckii ssp bulgaricus LB-12, Streptococcus salivarius ssp thermophilus ST-M5 and Lactobacillus acidophilus LA-K are dairy cultures widely used in the fermentation of dairy products. Homogenization is an essential process in dairy industry for making several products. High homogenization pressures (>50 MPa) are used to create stable emulsion, inactivate the pathogens and increase the protease activity of dairy cultures. Sparse literature is available on the influence of low homogenization pressures, and their effect on beneficial characteristics of dairy cultures is not well understood. The objective of this study was to determine the effect of low homogenization pressures on acid tolerance, bile tolerance, protease activity and growth characteristics of the three dairy cultures. The cultures were individually inoculated in cool autoclaved skim milk (4 C) and subjected to homogenization pressures of 0 MPa/ 0 psi (control), 3.45 MPa (500 psi), 6.90 MPa (1000 psi), 10.34 MPa (1500 psi) and 13.80 MPa (2000 psi) for 5 continuous passes. Growth and bile tolerance of samples were determined hourly for 10 hours; acid tolerance was determined every 20 minutes for 120 minutes; and protease activity was determined at 0, 12 and 24 hours of incubation. The experimental design was repeated measurements on complete randomized block. Data were analyzed using proc mixed model of statistical analysis system (SAS). Differences of least square means were used to determine significant differences at p<0.05 for main effect (homogenization pressure) and interaction effect (homogenization pressure * time). All low homogenization pressures improved acid tolerance of Lactobacillus delbrueckii ssp bulgaricus LB-12 but had no effect on protease activity and had negative effect on growth and bile tolerance of the bacterium. Low homogenization pressure of 6.90 MPa (1000 psi) improved the acid tolerance, bile tolerance, and protease activity but homogenization pressures had no effect on growth of Streptococcus salivarius ssp thermophilus ST- M5. Low homogenization pressures of 13.80 MPa (2000 psi), 6.90 MPa (1000 psi) improved acid tolerance, bile tolerance respectively of Lactobacillus acidophilus LA-K but had no effect on protease activity and growth of the bacterium. Some low homogenization pressures positively influenced some characteristics of the three dairy cultures.

Two experiments were conducted to study the effects of season and estradiol administration on dopaminergic input to the equine adenohypophysis. Experiment 1 began in the spring with 8 mares and 8 stallions and was repeated again in the summer, fall, and winter. Horses were given sulpiride injections of eight incremental doses (0.25 to 32 µg/kg BW). Within each group of 8 horses, half received the sulpiride in an increasing manner, the other half in a decreasing manner. Prolactin concentrations peaked in the first 15 to 30 min in all horses in all seasons. Prolactin areas under the curve increased (P < 0.001) with increasing doses of sulpiride, and were highest (P < 0.05) in March for stallions, but in June for mares. The calculated half-maximum values, which should be proportional to the dopaminergic input to the pituitary, were lowest (P < 0.05) in June and greatest in September. The variation in half-maximum values with season indicated a change in dopaminergic input to the pituitary, with lowest input occurring in June in both sexes. Experiment 2 was designed to determine if the degree of dopaminergic input to the adenohypophysis is altered by estradiol administration. Twelve geldings were used. On day 0, geldings received an i.m. injection of either estradiol cypionate (ECP; n = 6) or vegetable oil (n = 6) at one of two dose volumes (2 vs. 10 mL). On day 6, all geldings received an injection of sulpiride at 0.082 µg/kg BW in saline. Sulpiride injections were repeated every other day with the dose increasing each day, from 0.164 to 100 µg/kg BW. Estradiol pretreatment increased (P < 0.05) the prolactin response to sulpiride at the 2.56 µg/kg dose and higher. However, the half-maximum values for ECP-treated and control geldings did not differ, indicating that the amount of sulpiride needed to counterbalance the amount of dopamine reaching the pituitary was unaltered by estradiol treatment. It was concluded that estradiol likely stimulates prolactin production and secretion after sulpiride directly at the lactotrope level, rather than by decreasing hypothalamic dopamine input to the lactotropes.

Consumers are becoming conscious of their diet, increasing protein intake and avoiding carbohydrates and fats. Whey proteins have branch chain amino acids responsible for muscle building. Whey protein isolate (WPI) contains more than 90% protein. The effect of incremental addition of WPI on probiotic characteristics of pure cultures and cultures in yogurt and yogurt characteristics are not known. The hypothesis was that added WPI will influence the characteristics of yogurt culture bacteria in pure form and in yogurt. The objectives were: to determine the influence of added WPI on (1) acid and bile tolerance, growth and protease activity of pure cultures Streptococcus thermophilus ST-M5 and Lactobacillus bulgaricus LB-12, (2) growth, acid and bile tolerance of starter culture from manufactured plain yogurt, (3) the physico-chemical characteristics of yogurt over its shelf life and (4) the sensory attributes of yogurt. WPI was used at 0, 1, 2 and 3% w/v. Acid tolerance was conducted on pure cultures and cultures from manufactured plain yogurt at 30 minutes intervals for 2 hours of incubation and bile tolerance at 1 hour intervals for 5 hours. Yogurt was manufactured using 0 (control), 1, 2 and 3% WPI. For sensory evaluation, blueberry yogurt was manufactured using the same WPI concentrations. Physico-chemical analyses of yogurts were conducted every 7 days during 35 days of storage. Enumeration of yogurt cultures during yogurt´s shelf life was evaluated at 7, 21 and 35 days of storage. Sensory evaluation was conducted on yogurt 7 days after its manufacture. Data were analyzed using Proc Mixed model of SAS® 9.3 program and by analysis of variance (ANOVA) using Proc GLM. Significant differences between means were analyzed at α = 0.05 using Tukey´s adjustment. Use of 2% WPI improved acid tolerance of Streptococcus thermophilus ST-M5 in yogurt. Use of 2 and 3% WPI improved bile tolerance of Lactobacillus bulgaricus LB-12 over the 5 hours of incubation. WPI decreased syneresis of yogurts and improved sensory attributes of flavored yogurt. Overall liking scores were higher for 1% WPI yogurts compared to control. Overall, 1 or 2% WPI can be recommended in manufacture of higher whey protein yogurts.

Previous research has shown that rangeland forage production can be increased through fertilization. A study was conducted to determine if fertilization of various Utah range sites was economically feasible. Six range sites were selected for analysis. The addition of nitrogen increased forage production on three sites. Phosphorus had no effect in increasing production. Production functions of the form, Y = a + bN - cN2 , where Y is pounds of forage per acre and N is pounds of nitrogen per acre, were estimated for both fall and spring applications. Using current prices of Y and N the optimum rates of fertilization for maximum profit were determined. By comparing the profit per acre for fall and spring applications the most effective season of application was determined. On an irrigated tall wheatgrass (Agropyron elongatum) pasture the fall application was most profitable and the optimum rate of N was 215 lbs. / ac (assuming PN = $ .1207/lb. and PY = $ . 0073/lb.). On an intermediate wheatgrass (Agropyron intermedium) foothill site, fall was the most profitable season of application and 127 lbs. / ac of N was the optimum rate. On a crested wheatgrass (Agropyron cristatum) site (average precipitation of 11 to 12 inches) only the spring application was analyzed and the most profitable rate of application was 7 lbs. N / ac. The optimum rates of N were determined for various prices of nitrogen and forage in a sensitivity analysis.

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.

An increasing interest in fecal analysis as a method of determining diets of herbivores prompted research to determine if this method could be used successfully to determine diets of pronghorn antelope found in Utah's cold desert rangelands. In addition to fecal analysis, quantitative estimates of pronghorn diets were derived from rumen analysis and feeding site observations. Rumen samples were analyzed by three different methods : (1) microscopic, (2) gravimetric, and (3) point frame. In addition to field experiments, samples from a feeding trial with a diet of known composition were used to determine whether or not differential digestion of plant epidermis occurs. Fourteen male pronghorn antelope were collected between July, 1970 and June 4, 1971 on the Desert Experimental Range near Milford, Utah. A fecal sample was taken from the intestine of each. In addition, fecal samples and estimates of vegetative composition were collected at 14 sites. These, plus eight rumen samples collected from hunter kills during August 1970, were used to compare methods of rurren analysis and fecal analysis with the other conventional techniques used in this study. Of the methods used, the microscopic technique, as described in this study, provided the most accurate and efficient method of analyzing pronghorn rumen samples. fecal analysis results compared favorably to the other methods used. The known diet study indicated that differential digestion of epidermal fragments may occur under certain conditions.

An experiment was designed to study the effects of forage availability, season and intensity of grazing, and distribution and behavior of sheep on their forage preferences. Three grazing periods of 15 days each were used to study the effect of season. Each grazing period included a heavy and a moderate stocking intensity. Pastures were divided by a grid into 30.48 m x 30.48 m compartments. Each compartment was sampled for botanical composition of available herbage prior to and after grazing. Esophageally fistulated sheep were allowed to graze freely and positions of individual sheep with respect t o compartments were recorded at 5-minute intervals during the daily forage sample collection period. Immediately following collection of fistula samples, daily measurements were taken on leaf area index and height for all plant species. Estimates of aerbage yield and forage utilization were derived from heightleaf area measurements by regressions. Botanical composition of the diet was determined through microscopic analysis of plant cuticle fragments on dried, ground esophageal samples. Analysis of the dietary data indicated that season had no effect on the botanical composition of diets of sheep. However, grazing intensity significantly (P < 0. 20) affected diets of sheep. Significant differences (P < 0 . 01) were also found in proportion of plant species that comprised the diet at any particular time. Individual sheep were significantly (P < 0.01) different in their forage preferences . There were no significant changes in botanical composition of the compartments due to grazing. However. bare ground increased significantly (P < 0.10) more under heavy stocking than under moderate stocking. Herbage yield was found to be highly correlated with leaf area index and height (r2 = 0.85) in the ungrazed control pasture. Forage yield in the grazed pastures was a l so correl ated with leaf area index and height (r2 = 0.79) . Utilization was estimated as the difference between the two parameters . Sheep were observed to graze more heavily around the periphery of shrubs than in the interspaces. The heavily grazed areas around shrubs were found to be significantly larger in heavily stocked pastures (P < 0.10) . Observations of grazing behavior showed that sheep tended to orient themselves toward conspicuous objects . In so doing, they grazed a strip leading from one conspicuous object to another (ex. shrubs) . In an experiment designed to determine the role of such conspicuous objects in animal distribution and feeding behavior, sheep distribution, in relation to randomly-placed cardboard boxes. was found to be non-random and significantly (P < 0.05) related to the position of the boxes. It was also found that sheep grazed the herbaceous species to a certain height below which the plants became inaccessible to grazing. Micro-associations of plant species greatly influenced preferences. Sagebrush (Artemisia tridentata) plants exerted a negative effect on use of adjacent bitterbrush (Purshia tridentata) plants. This negative effect was determined by the distance between the two shrubs. This "critical distance" was found to be 56.1 ± 23.7 cm and was not affected either by season or stocking intensity . An equation was developed by multiple regression to predict diets of grazing sheep. This equation explained 52% of the variation in botanical composition of the diet. Visual orientation of individual sheep, while grazing, modified to a large extent their forage preferences.

The addition of the Streptococcus lactis culture in the pasteurized milk was studied, in an attempt to find the effects of the culture in prolonging shelf life of the milk. Various concentrations of the culture were tried to find the optimum concentration that would give favorable effect on keeping quality of the milk. It was found that the addition of Streptococcus lactis culture at the rate of 0.0001 percent has shown promising effects in prolonging shelf life of the milk at the storage temperature of 40 F. In addition to the above study, effects of added acid in the pasteurized milk, were studied. The adjustment of pH with the addition of the citric acid used in these studies, had no effect in extending the keeping quality of the pasteurized market milk. The acid treatment of the milk showed spoilage earlier than the control samples of the milk. Two temperatures, 40 F and 50 F were studied to find suitable temperature for storage of the milk. It was observed that the 50 F is not a desirable temperature for storage of pasteurized milk. A 40 F temperature was found better for storage of the milk. Bacteriological studies done simultaneously, on pasteurized milk stored at 40 F, showed that the coliform organisms did not multiply at that temperature. The initial bacterial counts on psycrophilic organisms were negative; but after seven days their presence was in large number. The number of organisms as determined by the Standard Plate Count, was not a reliable indicator of the keeping quality during storage temperature of 40 F.

This paper entails the economic and biological interpretation of the response of rangeland grasses to nitrogen fertilization. Six sites throughout Utah received graduated rates of fertilizer. The coefficients of the production function Y = a + bN - cN2 were identified. An initial production and a carry-over response were identified on sites recei ving greater than ten inches of annual precipitation. Optimum fertilization rates may be identified by equating the marginal physical product to the ratio of the price of nitrogen to the price of the forage. Forage response to nitrogen is reflected strongly in the early growth response in which fertilizer rates of 15 to 120 pounds of nitrogen per acre produce adequate forage for grazing 4 to 18 days prior to unfertilized range.

A reliable technique for obtaining late prophase, prometaphase and greater numbers of metaphase chromosomes is presented. The increased number of mitoses and high resolution chromosomes were obtained using a modification of the typical three-day blood c ulture technique in which the cell cycle was temporarily blocked at the G1 -s border with methotrexate. A high resolution G-band idiogram is presented using a system similar to the standardization of human chromosomes. The use of this technique and system of nomenclature will facilitate routine analyses of horse chromosomes and provide a basis for the identification and recording of chromosome aberrations in this species. C-bands and NORs of the domestic horse are also described. C-bands, NORs and high resolution G-bands of control horses were compared with those of horses affected with Hereditary Multiple Exostosis. No differences were found on NORs, C- and G-bands between control and exostosis horses.