It has been proposed that Bos indicus when compared with Bos taurus embryos are more sensitive to cryopreservation procedures due to higher intracellular lipid content of the embryos. With cyropreservation of Bos indicus embryos increasing for export, it is essential to improve the viability of these cryopreserved embryos. In Experiment I, M-II oocytes from mice, pigs and cows were subjected to two different procedures to evaluate lipid content. The lipid content present in pig oocytes was significantly (P<0.05) higher when compared with mouse and cow oocytes. Pig oocytes had a lower settling point in the sucrose buoyant density gradient and higher Nile Red units, which indicated higher lipids present in the oocytes. In Experiment II, it was determined that M-II oocytes aspirated from superstimulated Brahman donors were significantly higher (P<0.05) in lipid content compared with English breed donors. The lipid content present in Brahman oocytes was higher when compared with English breeds when tested with a sucrose buoyant density gradient and Nile Red staining. In addition, donor females with higher body condition scores were significantly (P<0.05) higher in oocyte lipid content when compared with donor females of lower body condition scores. Furthermore, animal body condition scores, cholesterol and triglyceride levels prior to oocyte aspiration may be indicators of intracellular lipids in the oocytes and embryos. To our knowledge, this is the first report that evaluated intracellular lipid content of M-II oocytes of different beef breed types using a sucrose buoyant density gradient and Nile Red staining.

Health benefits of Lactobacillus acidophilus include providing immune support for infections or cancer, providing a healthy replacement of good bacteria in the intestinal tract following antibiotic therapy, reducing occurrence of diarrhea in humans, aiding in lowering cholesterol and improving the symptoms of lactose intolerance. Consumer demand exists for new dairy products. There are several types of yogurt like stir curd, set curd and drinkable yogurt and they all need to be refrigerated. Moreover there are very few dairy products that can be stored at room temperature and not many dairy foods are finger foods. A novel yogurt product like a yogurt jerkey with L.acidophilus could be a dairy product that is a finger food, which can be stored at room temperature and have health benefits. The objectives of the research were to study the effects of 0, 1, 10 and 100g of Lactobacillus acidophilus /gal of novel yogurt product on L. acidophilus, yogurt bacteria, coliform, yeast and mold counts and TPA (Texture Profile Analysis) hardness, springiness, chewiness, cohesiveness, and adhesiveness over 0, 1, 2 and 3 months of storage of the novel yogurt product at room temperature. The interaction effect of treatment and time was significant for all attributes studied except adhesiveness. Yogurt bacterial counts were significantly higher in all treatments at month 3 compared to control. With the use of 10g and 100g/gal addition of L.acidophilus there was a significant decrease in L.acidophilus counts at month 2 and month 3 when compared to month 0. Hardness of product with L.acidophilus use at 100g/gal was significantly lower when compared to the control and treatments 1, 10g/ gal over months 1, 2 and 3. Springiness and chewiness of all treated samples at month 2 were significantly higher than control. Cohesiveness was significantly higher with all levels of L.acidophilus compared to control. Use of probiotics favorably affected some characteristic of the novel yogurt product. Use of probiotic L.acidophilus at 100g/gal can be recommended in the manufacture of a healthy novel yogurt product such as a yogurt jerkey or bite sized chewable yogurt capable of being stored at room temperature.

Forty-eight calves (heifers n=20, bulls n=28) were randomly assigned one of four dietary treatments which included no additive (C); the yeast culture Saccharomyces cerevisiae (YC); the probiotics Bacillus lichenformis and Bacillus subtilis (P); and both yeast culture and probiotics (YCP). Calves were administered treatments from day 2 to 56 in starter and from day 57 to 84 in grower diets. Body weights were measured at birth and weekly thereafter until day 112 of age. Wither and hip heights were measured weekly. Feed intake, water intake, and fecal scores were recorded twice daily until day 56. Rumen fluid was collected on days 14, 28, 42, 56, 70, 84, and 112 for analysis of pH, VFA, and NH3. Blood was collected on d 28, 42, 56, 84, and 112 for analysis of BHBA concentrations. There was a sex*treatment interaction (P < 0.01) for starter intake. Males receiving P consumed less than other calves. Females consuming C ate less than males on the same diet. Females consuming YC ate more than males consuming YC. There was a tendency (P = 0.06) for calves receiving YC to consume more than calves not fed YC. Calves consuming P drank less water than all other calves (P = 0.01). There was a sex*time*treatment interaction for body weight (P < 0.05). Females consuming C and males consuming P showed a decreased body weight over time (P < 0.05). Calves consuming YC showed an increased body weight at week 6 and 8 (P < 0.05). There were no differences among treatment groups for hip and wither height (P > 0.1). Calves consuming YC had higher fecal scores than those with no YC (P < 0.05). There were no differences among treatments on pH, NH3, BHBA, butyrate, and propionate (P > 0.1). A sex*treatment*week interaction occurred for acetate (P < 0.05). Calves consuming P had an increase in acetate, with females showing a greater increase over males. Incorporating YC into starter may result in an increase in growth. However, this effect did not continue after weaning. Rumen development remains unaffected by addition of YC and P to grain diets.

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.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2000. / Thesis based on five papers, which are included. Includes bibliographical references.

Thesis (M. Agr. Sc.)--University of Queensland, 2002. / Includes bibliographical references.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2001. / Includes bibliographical references.

No description available.

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.