The proteins found in milk are largely important in the functionality of many dairy products and dairy processes. The casein micelle system in milk is a complex and highly studied system. The micelle is thought to be a sponge like structure containing four caseins, αs1, αs2, β, and κ casein, and bound together with colloidal calcium phosphate. When a chelating agent such as a citrate, phosphate, or polyphosphate are added to milk systems, the CCP is bound to the chelator and removed from the micelle. It has been shown through past research that the use of calcium chelating agents disrupts the calcium phosphate equilibrium and allows for the dissociation of the casein micelle and release of the individual caseins. Once the caseins are disrupted from micellar form and in solution, it may be possible to separate out different casein streams for functional usage in dairy products using common separation techniques. This thesis project seeks to evaluate the feasibility of separating milk treated with calcium chelators using various separation techniques to evaluate the individual casein fractions of this disrupted system. Four separation methods (ultracentrifugation, membrane filtration, heat coagulation, and coagulation based on pH) were employed to separate out the caseins based on selected properties, specifically density, molecular weight, and solubility. In ultracentrifugation, three speeds were tested, the heat coagulation study tested two temperatures, and pH based coagulation tested four different pHs to determine their impact on overall protein levels and individual casein yields. Skim milk powder was reconstituted and chelator was added at 1, 50, or 100 mEq/L treatment level. These samples were then separated using aforementioned techniques, and the supernatant or permeate was analyzed for total protein content, individual casein composition, turbidity, and mean particle size. Analysis of centrifugal separation studies shows the interaction between chelator type, chelator level, and centrifugation speed had a significant impact on the amount of protein released from the casein micelle (p Coagulation trials based on pH were also shown to have a significant interaction between chelator type, chelator level, and sample pH effecting the protein levels and casein composition (p Membrane filtration showed low protein yields in permeate, however trisodium citrate 100 mEq was still shown to have significantly higher permeate % protein levels (p The use of heat based coagulation as an individual casein separation technique for chelated samples is not recommended, as the casein micelle system itself is extremely heat stable, and the use of calcium chelators only increases the heat stability further. Because of the increased heat stability, no coagulum was formed in samples upon heating, and therefore, no separation and analysis could be done. Improving our knowledge of pretreatment of milk prior to separation and the effectiveness of different separation methods on chelated milk products may result in information leading to the ability to separate out milk fractions that provide unique or improved properties for product applications.

Forty high producing early to mid lactation Holstein cows were blocked according to stage of lactation and previous two-week milk yield (experiment 1) . Eight ruminally and duodenally cannulated nonlactating Holstein cows were used for experiment 2. The objective was to determine the effects of the ration's high fat content (11.53%) when rumen degradable or rumen undegradable protein is fed with or without added niacin. Cows received one of five treatments: 1) basal ration (TMR); 2) basal ration with added rumen undegradable fat (RUF) (1.6 kg); soybean meal (SBM) (1.73 kg), and niacin (12 g); 3) same as treatment 2, without niacin; 4) same as treatment 2 but replacing the soybean meal with undegradable protein (UIP) (1.9 kg ) ; and 5) same as treatment 4, without niacin. Rations and water were offered ad-libitum for 10 weeks. Intake for experiment 2 was limited to 18 kg TMR, 0 .76 kg RUF, 0 .88 kg SBM or UIP, and 6 g niacin. All cows in experiment 2 received the five treatments by the end of five collection periods separated by 21 d adaption. RUF increased dry matter intake (22.95 vs. 23 . 72 kg/d ) and mean body weight (607 vs. 637 kg ) , but decreased milk protein, lactose and SNF (proportion and yield); and 4% FCM without affecting daily milk yield. RUF, SBM, and N did not affect milk production. Milk protein percentage, protein yield, lactose percentage, SNF percentage, and yield were decreased by UIP supplementation. Niacin had a negative effect on milk fat percentage and yield, and milk protein percentage when fed with RUF and UIP . Supplements did not affect milk protein components. RUF increased plasma glucose (56.8 vs. 63.5). RUF addition increased AD and ND digestibility while decreased fatty acid digestibility. UIP improved ND digestibility in the lactation trial. For experiment 2, UIP increased rumen propionate percentage, thus reducing acetate to propionate ratio. Niacin increased total VFA production (128.6 vs. 114.3 umol/ml) . RUF, UIP, and niacin increased total bacterial population. RUF reduced cellulolytic bacteria in rumen fluid. Nutrient rate of passage and digestibility were unaffected by treatments except for dry matter and RUF digestibility that were reduced by RUF supplementation.

Roughage is the cheapest source of nutrients for herbivorous animals, and alfalfa is the best of the roughages because animals consuming alfalfa as a major part of their diet have an adequate supply of protein energy, and a considerable proportion of needed vitamins.

One hundred eighty-seven survey questionnaires asking for reproductive information for 1985 were sent to dairymen in Utah and Southeastern Idaho. Forty- two herds with current DHI information and whose owners or managers completed and returned the questionnaire were used to estimate economic losses due to reproductive problems, especially excessive days open, in Utah and Southeastern Idaho. Average days open for herds surveyed were 122.4 days with a standard deviation of 22.6 days, and a range of 89 to 177 days. Several factors were significantly correlated with days open including services per conception, previous calving interval, and missed heats. Missed heats accounted for most of the variability in days open with an r2 of .82. Surveyed dairymen were losing an average $1.22 per cow per day due to excessive days open beyond 90 days. In addition they were losing approximately $22.87 per cow per year due to reproductive levels inferior to the top expected levels and veterinary costs associated with reproductive problems other than excessive days open. Although this is the estimated average loss in Utah and Southeastern Idaho, dairymen should try to determine losses in their own herds due to reproductive problems because of the extreme variability which exists among herds. Utah and Southeastern Idaho dairymen are suffering se rious economic losses due to excessive days open and they need to improve their heat detection methods to r educe these losses .

Sixteen lactating regularly cycling dairy cows (14 primiparous, 2 multiparous) were used to determine the effects of somatotropin administration on basal, peak, and pulse luteinizing hormone concentrations during the breeding period. In addition, the effects of somatotropin administration on the pituitary response to a gonadotropinreleasing hormone challenge was studied. The experimental group received daily somatotropin treatments (25mg) for 24 days. The control group received a daily placebo. All animals were treated with three injections of prostaglandin F2-alpha (25 mgjtreatment) for estrus synchronization. Somatotropin and placebo treatments began with the second prostaglandin injection. Sixty hours following the final prostaglandin injection, all cows were catheterized via a jugular vein. Blood samples were collected at 15-minute intervals for 24 hours. The estimated mean time to the preovulatory luteinizing hormone peak was 62.5 +/- 1.8 (SE) hours among 6 of 16 animals responding. Mean plasma peak luteinizing hormone concentration (regardless of treatment) was 13.49 +/- 4 .18 (SE) ng/ml. On Day 10 of the subsequent estrous cycle, blood samples were collected at 20-minute intervals for 6 hours to determine basal levels of luteinizing hormone. Immediately fo llowing this collection period, a gonadotropin-releasing hormone challenge (100 ug) was administered intravenously. Blood samples were collected at 15-minute intervals for an additional 8 hours. BST did not affect basal, peak, or pulse luteinizing hormone concentrations . There were no differences in basal luteinizing hormone concentration, pulse amplitude, pulse interval, or pulse frequency. BST did not affect the pituitary response to a gonadotropin-releasing hormone challenge. Time to peak, time to return to basal, peak concentration, peak width, and peak luteinizing hormone amplitude were not different among treatment groups following the gonadotropin-releasing hormone challenge. Milk production of BST-treated cows was increased 7% (2.1 kg/d) over controls.

Milk serum proteins have been shown by other workers to be partially protected from heat denaturation by the presence of milk solids (8, 15, 16) and whole caseinate (14). This study revealed that some serum proteins (B-lactoglobulin), as shown by the Harland-Ashworth test (14, 17), were more readily denatured in skimmilk than in rennet whey. A comparison of the heat denaturation rate of serum proteins in whey as opposed to those in whey containing 2.5 percent isoelectric casein was also studied. A striking protection of serum proteins seemed apparent in the presence of isoelectric casein. However, it was learned that isoelectric casein interferes with results of the Harland-Ashworth test, and by taking this interference into account, that isoelectric casein has no affect on the heat denaturation rate of serum proteins. Some proteins are more sensitive to heat in the presence of miceller casein than in the presence of isoelectric casein or no casein at all. The addition of sulfhydryl-group blocking agents (P-chloromercuribenzoic acid and N-ethylmaleimide) inhibited serum protein denaturization in both skimmilk and rennet whey. Reactions of sulfhydryl groups following their liberation by heat resulted in much of the physical instability measured by the Harland-Ashworth test. The complex between B-lactoglobulin and K-casein, if it had any affect at all, was not one of the significant sulfhydryl-group reactions involved in the heat denaturation of the serum proteins.

Thirty-six dairy calves were observed for four months to determine the effect of three housing methods, group, individual and isolated on body weight gain, feed consumption, age when started to consume grain, daily activity patterns, open field test of behavior and social rank. Six calves were assigned to each of the three treatments in two separate trials of eighteen calves. These calves were raised in their treatment for approximately two months and then weaned and placed together in a group of eighteen for two more months. Treatments ranked in order from high to low according to least squares means for weight gain over four months were: group, individual and isolated. The differences were, however, not significant (P>.05). There was a significant difference in weight gain from weaning until four months between the group calves and the isolated calves, with the group calves gaining weight faster during this weaned period (P<.05). Group calves began consuming grain at a younger age (P<.Ol) than the calves on the other two treatments, but total feed consumed over the first 10 weeks was not significantly different (P>.05). Isolated calves tended to spend a greater portion of the time lying down than calves in the other two treatments but the difference was not significant (P>.05). In the open-field test isolated calves entered more squares than the group or individual calves, but the group calves were the most vocal of the calves in the three treatments (P<.Ol). The group calves placed higher in the social order and won a higher percentage of encounters (P<.Ol) than the individual or isolated calves during the weaned period.

One hundred sixteen third- and fourth-service lactating dairy cows from five cooperating herds were used to compare the pregnancy rate of cows given Gonadotropin Releasing Hormone five minutes following insemination with pregnancy rate of control cows. In addition, milk production level, age at service and days in milk at time of service were used to compare pregnancy rates. Milk production level was expressed as relative value (percent of herd mature equivalent production). There were no differences between treated and untreated control cows in pregnancy rate. In addition, there were no differences between service number (3 or 4), relative value group, age at service, days in milk at time of service, treatment by service, treatment by relative value, service by relative value, age squared and days in milk squared in pregnancy rate.

Livestock have been fed yeast as a feed supplement for more than 100 years Stone, C. 00). Yeast is a microscopic, single cell fungi of the plant kingdom. Of the 50,000 species of fungi, only 60 different genera of yeast representing about 500 different species exist. A few of these are used commercially in the animal feed industry as active dry yeast or yeast culture (Kreger, van Rij, 1984). Yeast culture consists of live yeast cells, plus the medium on which yeast is grown. Yeast products are commonly fed as pro-biotics, but little is known about their effects. Some studies have reported that yeast products increased milk yield and milk fat percentage; however, other studies found that yeast products had no effect on any of these factors (Middelveld. H 1998). A three phase trial, starting August 2003 and ending February 2005, was conducted at the Western Kentucky University Agricultural Research and Education Complex (Dairy facilities), in Bowling Green, Kentucky. Trial 1 evaluated the affect of dietary yeast, (WY) a, fed to cows in early lactation during heat stress conditions. Trial 2 evaluated the effect of dietary yeast WY fed to pre and post-partum cows during weather stress conditions. Trial 3 evaluated milk yield of cows fed post-partum cows 2 different types of yeast, (CC5)b or (YS)C, versus a no yeast control group (CG)d, during weather stress conditions to post-partum cows. Cows in trials 1 and 2 were fed a total mixed ration (TMRs) consisting of corn silage, alfalfa hay and haylage, grain mix, whole cottonseed and controlled access to alfalfa pasture; while the third trial cows received a TMR of corn silage, alfalfa hay, whole cottonseed and grain mix. In all trials, milk weights were captured and recorded at each milking using electronic weigh meters, which download into a computer. Seven day average milk weights were used for the analysis in all the trials. Data were analyzed using SPSS 13 and Microsoft Excel XP 2006, standard statistical analysis software. In trial one milk yield and energy corrected milk (ECM)were statistically higher (p<0.05) in the Holstein WY group. The limited Jersey sample size did not provide adequate statistical data for analysis. In the second trial, milk yield and ECM were statistically higher in the Jerseys in trial WY versus the Jerseys in the CG group. There was no significant statistical difference in Holsteins treated WY versus the Holsteins in the CG group. In the third trial, ECM was statistically significant at (p= 0.05) in the CC5 groups versus the CG group. The CC5 group differed from YS group at the (p= 0.05) level in the Holstein groups as well as in the Jersey groups. The statistical difference in ECM may be due to the different composition of the yeast used in the diet plus the stress caused by environment. The CC5 group and YS groups were statistically higher in average milk yield (p=0.05) han the CG group. A positive response on milk yield appears to be found in those groups feed yeast. Based on these completed trials, the usage of yeast has a moderate impact on milk production as well as milk composition. These heat and transition trials suggest positive economical returns based on ECM from the usage of yeast.

Extensive research has been conducted to decrease the environmental impacts of dairy farming by using forages containing condensed tannins (CT). In this study, it was hypothesized that feeding CT-containing birdsfoot trefoil (Lotus corniculatus, BFT) to lactating dairy cows would result in a decrease in N degradation in the rumen, causing a shift in N partitioning into milk and manure outputs, compared with alfalfa hay. Urine N is more volatile and harmful to the environment compared with fecal N. By reducing urine N, overall N utilization efficiency can improve. It was our goal to verify how the changes in N partitioning would affect the overall N utilization efficiency by dairy cows fed BFT hay-based high-forage diet. The results in this report showed that feeding BFT-hay diet reduced protein degradation in the rumen, decreased N excreted to milk and urine, and increased N excretion into feces, resulting in decreased urinary-N:fecal-N ratio due to feeding BFT-hay diet. However, the change in the N excretion routes was not associated with N utilization efficiency, which may have resulted from poor nutritive quality of BFT hay. Although the BFT hay fed in the current study was in a very mature condition and was of poor quality, DM intake and milk yield were similar in both treatments. Therefore, it is implied that BFT hay can replace alfalfa hay in dairy rations, because even poor quality BFT hay compared with alfalfa hay led to similar lactational performance and a beneficial shift in N excretion into environment.