Doctor of Philosophy / Department of Animal Sciences and Industry / Barry J. Bradford / The ability of nutritional supplements to generate responses in productive animals at different physiological stages, and their interaction with the particular gastrointestinal tract of ruminants have created the necessity to explore effects beyond productivity. Modulation of immune function and inflammatory processes, modifications of nutrient metabolism, and interactions with the ruminal microbial population are effects attributed to supplements that encouraged the formulation of the set of experiments described in this dissertation. The first experiment was designed to test the effects of arachidonic and docosahexaenoic acids supplemented in milk replacer for Holstein calves during the pre-weaning period on the immune system, lipid and glucose metabolism, and growth performance when animals underwent a vaccination protocol. Neither supplemental fatty acid source affected productivity, cytokine production, antibody production, or CD4 and CD8 cell proliferation. A treatment effect on glucose and NEFA plasma concentration was observed. Polyunsaturated fatty acids, mainly DHA, lowered glucose and NEFA levels compared to control; moreover, a dose effect was observed indicating that increasing amounts of PUFA decreased plasma glucose level. The second experiment tested the effects of Co carbonate (CoCarb) and Co glucoheptonate (CoGH) at different concentrations of Co on in vitro fermentation rate, fermentation end-products, and DM and NDF disappearance. Dry matter and NDF disappearance increased with CoGH relative to CoCarb at 1.0 ppm Co or less. CoCarb at > 3.0 ppm appeared to stimulate the biohydrogenation of long-chain fatty acids whereas CoGH had limited effects on this process. Finally, the third study evaluated responses to chromium propionate during peak lactation and interactions between chromium and rumen-protected lysine and methionine. Chromium propionate increased feed intake and tended to increase energy-corrected milk yield. Primiparous cows showed greater responses in feed intake and milk protein yield than multiparous cows. In this study, feeding chromium propionate near peak lactation increased feed intake and tended to increase productivity but no benefits of supplementing rumen-protected lysine and methionine were observed. Overall, nutritional supplements helped to regulate different biological functions in ruminants; their utilization is not always is feasible, but the results of these experiments provide guidance about effectiveness during different physiological situations.

The use of microfiltration as an alternative to pasteurisation to reduce the microbial load of raw skimmed milk is a well established technology. However, its application in reducing bacteria from highly viscous dairy based solutions has not due to issues of low flux and high fouling tendency. This study involves the application of microfiltration to remove spores from high solids content Milk Protein Isolate (MPI) solutions. MPI feeds were inoculated with Bacillus mycoides spores a safer alternative to Bacillus cereus, a psychrotrophic spore forming bacteria found in dairy feeds. Suitable protocols for MPI resolubilisation, Bacillus mycoides cell and spore preparations were established and the membranes, MPI and spores were fully characterised by scanning electron microscopy (SEM), particle size distribution, rheology and pure water flux (PWF) measurements. Feed and permeate samples collected during experiments were analysed for solids content by oven drying, protein content using the Bradford assay and spore content using PetrifilmTM Aerobic count plates. To try and determine an optimum protocol for MPI filtration, a variety of filtration rig set-ups, modules and membranes were tested. Experiments were carried out at different MPI concentrations (4 – 16 wt%), cross flow velocities (CFV’s) (0.7 – 2.0 m s-1) and transmembrane pressures (TMP’s ) (1 and 2 bar). The filtration of 15 wt% MPI proved challenging. The best set of results were obtained using the 12.0 μm membrane at 1.4 m s-1, producing a 27 LMH flux, 96.5% protein transmission and a 2.1 log spore reduction. These results indicate that large pore ceramic microfiltration may be a suitable technology to replace or augment pasteurisation for high solids content dairy feeds. The effect of backwashing using different durations and frequencies was investigated. Backwashing parameters of 10 seconds every 5 minutes at 1 bar were found to be the most effective. The optimum cleaning regime found for MPI fouled ceramic membranes involved a long rinsing backflush at 1 bar, acid and alkali steps without backwashing, which produced a 99.6% flux recovery.

Digitized by Kansas Correctional Industries

Doctor of Philosophy / Department of Animal Sciences and Industry / Barry J. Bradford / Jeffrey S. Stevenson / Four experiments were conducted to assess nutritional and hormonal strategies to improve fertility in lactating dairy cows. In experiment 1, metabolites (-4, -2, +1, +2, +5, and +7 wk) and steroid hormones in ovarian follicular fluid (FF) and blood serum (BS) were examined in Holstein cows (n = 59) individually fed Saccharomyces cerevisiae fermentation product from -4 through +7 wk (calving = wk 0). Neither metabolites nor hormonal concentrations in BS or FF differed between treatments. In experiment 2 a rumen-protected glucose (RPG) product was supplemented at varying doses in the diet of lactating dairy cows with the objective to increase concentrations of glucose and insulin resulting in decreased activity of liver cytochrome P450 2C and P450 3A, thus increasing blood progesterone concentration. Neither pre-feeding nor post-feeding concentrations of glucose differed among treatments. Pre-feeding insulin did not differ among treatments, but a difference in the concentration of insulin (postprandial minus pre-prandial) was detected (P = 0.01). The increase in insulin was greater in control cows relative to the mean of the 3 RPG doses. We conclude that the insulin response to the RPG diets was diminished relative to the control. Supplementation with RPG did not impact concentrations of progesterone. Experiment 3 tested: (1) a shortened version of Ovsynch (SS: GnRH-1 -7 d - PGF2α - 24 h - PGF2α - 32 h - GnRH-2 - 16 h - AI) that excluded GnRH-1 to resynchronize ovulation in cows bearing a corpus luteum (CL) after a non-pregnancy diagnosis (NPD); (2) the value of including progesterone-releasing intravaginal insert + Ovsynch (OVS + CIDR) in absence of a CL compared with presence of a CL + OVS; and (3) the accuracy of detecting a functional CL by transrectal ultrasonography. Pregnancy per AI (P/AI) risk tended (P = 0.09)) to be greater for OVS than SS but did not differ from OVS + CIDR at 32 d (30.3% [n = 644], 25.7% [n = 678], and 25.9% [n = 270]), respectively. In SS cows, P/AI was greater (P = 0.01) when cows had a functional CL (progesterone was ≥ 1 ng/mL) vs. a nonfunctional CL at d 0, but did not differ from OVS cows. Short synch is a viable alternative to an entire OVS treatment when CL status is accurately detected. Experiment 4 was performed in 2 herds to determine if administering PGF2α concurrent with timed artificial insemination in lactating dairy cows would enhance P/AI. Pregnancy per AI at d 32 and 80 did not differ between treatments. Cows treated with PGF2 alpha in one herd produced more twins than control cows (11.7 vs. 3.2%), whereas no treatment difference was detected in the second herd (5.6 vs. 5.6%), respectively. We conclude that i.m. treatment of lactating dairy cows with 10 mg of PGF2α concurrent with timed AI did not improve P/AI or embryo survival, but increased twinning in one herd. Further research is warranted to determine nutritional and hormonal strategies to improve fertility.

No description available.

No description available.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Titus O. Awokuse, Dept. of Food & Resource Economics. Includes bibliographical references.

The purpose of this study was to describe the herd antibody status to Salmonella Typhimurium as estimated from co-mingled milk samples and to describe the resulting geographical patterns found in Texas dairy herds. Bulk tank milk samples were collected from 852 Grade A dairies throughout Texas during the summer of 2001. An indirect enzyme-linked immunosorbent assay (ELISA) using S. Typhimurium lipopolysaccharide was performed with signal to noise ratios calculated for each sample. The ELISA ratio was used in fitting a theoretical variogram and kriging was used to develop a predicted surface for these ratios in Texas. A spatial process with areas of higher risk located in the panhandle and near Waller County was apparent. Lower risk areas included Atascosa, Cooke, Collin, Titus, Comanche and Cherokee Counties. Subsets representing large dairy sheds in northeast Texas, the Erath County area, and the Hopkins County area were also evaluated individually. Each result illustrated a spatial process with areas of low and high ELISA ratio predictions. Cluster analysis was performed for the entire state with cases defined as herds having milk ELISA ratios greater than or equal to 1.8. Using this cutoff, the prevalence of herds with positive bulk tank milk ELISAs was 4.3%. Significant clustering of cases was demonstrated by the Cuzick and Edward's test. The spatial scan statistic then identified the two most likely clusters located in and near the Texas Panhandle. This study demonstrated that the distribution of S. Typhimurium antibodies in bulk tank milk in Texas is describable by a spatial process. Knowledge of this process will help elucidate geospatial influences on the presence of S. Typhimurium in dairy herds and enhance our understanding of the epidemiology of salmonellosis.

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.

Dairy production technologies