Brucella is a genus of Gram negative, facultative intracellular pathogens which cause brucellosis, one of the most wide spread zoonotic diseases. Brucellosis causes a severe economic burden due to reproductive loss in animals and human infection. Vaccination of animals has proven to be the most effective means of controlling brucellosis; however the current live-attenuated vaccines are not considered ideal. The live-attenuated vaccines Brucella abortus Strain 19 and RB51 remain pathogenic to humans, and the former interferes with diagnostic tests due to induction of antibodies against the O-polysaccharide. DNA vaccination with single antigens has proven to be successful at protecting mice against B. abortus challenge, however this method is less effective in large animals. Immunization with a combination of antigens has been shown to provide more protection than single antigens. In an attempt to develop a better DNA vaccine, two multivalent multi-epitope plasmids were constructed using known protective antigens and bioinformatics technologies. Epitopes predicted to induce cell-mediated immunity were selected from Cu/Zn superoxide dismutase, outer membrane protein (Omp) 16, Omp19, ribosomal subunit L7/L12, BP26, ribosomal subunit L9, and Omp25. The plasmids were transfected into Chinese hamster ovary (CHO K1) cells, and PCR was used to confirm presence of the sequences in the genome. The transcription of the BabV1 and BabV2 genes to RNA was confirmed using RT-PCR. Finally, Western blots using sera from Strain 19 infected goats suggest the protein is not recognized by the humoral response of vaccinated animals. Further research is required to determine if the p425/BabV1 and p425/BabV2 vaccines are recognized by the cell-mediated immune response of infected or vaccinated animals.

Parasites cause considerable economic losses in all fields of agriculture. In the poultry industry, coccidia infections are of major significance costing billions of dollars every year. Research on condensed tannins (CT) has been shown to be effective against various parasites such as gastrointestinal nematodes and Eimeria spp. in small ruminants. This study tested the effects of the CT containing forage, sericea lespedeza (SL), on broiler chickens infected with live Eimeria spp. oocysts. In Study 1, 300 Ross 708 broiler chicks were divided into 6 groups (negative control, positive control w/BioCox, 0% SL, 5% SL, 10% SL, 15% SL). In Study 2, 250 Ross 708 broiler chicks were divided into 5 groups (negative control, positive control w/BioCox, positive control w/Corrid, 0% SL, 10% SL). Chicks were grown for 18 days in battery cages. All groups, except the negative control, were infected with a high dose (approximately 100,000 oocysts per chick) of oocysts at day 4 via gavage. SL was fed to the appropriate groups from day 0 to day 18. Data analysis included fecal oocyst count (FOC), weight, feed conversion, lesion scoring and histopathology. Results from Study 1 indicated that 10% and 15% SL, significantly decreased FOC. Reduced body weight (BW) and feed conversion for all SL fed chicks were also noted. Lesion scoring was not of value. Histopathology suggested a potential mechanism of action of CT, in that only the SL fed chicks had developing stages in the intestinal mucosa. Therefore, CT may act to slow development allowing the immune response to mature. In Study 2, FOC was not affected by the 10% SL treatment. Reduced BW and feed conversion were also observed as in Study 1. Feeding broiler chicks, a diet containing SL may be beneficial for controlling Eimeria spp. infection, but production was negatively affected. Therefore, feeding SL should not be recommended at this time pending further research to address the production issues.

Two experiments evaluated using an estrous-detection patch to identify animals that are in standing estrus at split-timed AI (STAI) and the necessity of a gonadotropin-releasing hormone (GnRH) injection at STAI on a 7-Day CO-Synch + CIDR protocol. In experiment 1 (n=216) and in experiment 2 (n=101), multiparous lactating crossbred beef cows were stratified by age, BW, BCS, and post-partum interval to 2 treatment groups: CTRL=timed-AI (TAI) at 72h post CIDR removal, or TRT=STAI at 72 or 84h post CIDR removal. All females received GnRH plus a CIDR on d0, prostaglandin-F2α, CIDR removal, and an Estrotect estrous-detector patch on d7. At 72h post-CIDR removal, a patch score was assigned (PS1 <50% removed; PS2 ≥ 50% removed) to all females. Cows in the CTRL group were administrated a second GnRH injection at 72h TAI. Cows in the TRT group with a PS2 were not administrated GnRH at TAI. At 84h, the remaining TRT cows were given a second PS and cows with a PS1 received a GnRH injection and cows with a PS2 did not. Blood samples for Progesterone concentration were collected on d-11 and 0 to determine percent of cows cycling. Data were analyzed using Proc Genmod with treatment and AI technician as fixed effects, sire as a random effect, and BW, BCS, age, and PPI as covariates. In experiment 1, TAI pregnancy rates were similar (P=0.81) between the CTRL (40.8%) and TRT (43.4%) groups. Pregnancy rates tended to be greater (P=0.07) for cows with a PS2 (50.3%) compared with a PS1 (29.4%). However, by extending TAI to 84h in unresponsive cows, 82.0% of the TRT cows did not receive a second injection of GnRH at TAI. In experiment 2, TAI pregnancy rates were similar (P=0.80) between the CTRL (32.3%) and TRT (38.6%) groups. Pregnancy rates were greater (P=0.04) for cows with a PS2 (70.6%) compared with a PS1 (19.4%). By extending TAI to 84h in unresponsive cows, 37.1% of the TRT cows did not receive GnRH at TAI. Using a heat-detector can reduce the percentage of cows that require GnRH at TAI without compromising pregnancy rates.

This thesis is based on the evidence of the use of range by laying hens from two separate studies that were carried out on commercial flocks. The first study involved a direct observation of 6 flocks of laying hens whereas the second study was carried out on a single flock of laying hens using a still digital camera. Mapping of the outdoor range into three zones, namely; apron (0-10metres), enriched (10-50metres) and range (beyond 50metres), was carried out in both studies determine whether it influenced the distribution, behaviour, nearest neighbour distance (NND) and feather condition of the hens. Based on the estimates of the total number of hens recorded outdoors, it was found that 14.5% of the hens used the range in the first study, with 6.0% of the hens seen in the apron, 4.8% in the enriched and the remaining 3.7% in the outer range zone. This ranging pattern was further confirmed by the quadrat head counts, where the hens used the apron most but showed a significant decrease in the use of other outdoor zones as distance increased from the shed (p < 0.001). The results of the two studies showed that range use peaked in the morning and decreased significantly in the afternoon (p < 0.001). Range use was found to increase significantly with age (p < 0.001) in the first study, although there was a significant decrease in the number of hens outside the shed as the flocks got larger (p < 0.001). The age effect reported in the six-flock study was complemented by the significant positive effect of the week of outdoor access on the ability of the hens to use the range (p < 0.001) in the single flock study. Range use increased as outdoor temperature rose in the six-flock study whereas increased outdoor temperature resulted in a decline in range use in the single flock study. NND of the hens was ii measured in the six-flock study and was found to decrease significantly towards the shed (p < 0.001) and as the hens aged (p < 0.001). There was evidence that the use of distant and less crowded outdoor locations by the hens in the first study was associated with improved feather conditions. The evidence presented in the two studies presented in this thesis showed that the hens were unevenly distributed in the range, with reduced hen density (hen/m2) towards the outer range and that an improvement in the use of distant parts of the range may have beneficial effects on the hens.

This study focused on testing the effects of agricultural education on urban high school students’ career choices. It looked into how students view agriculture, how they perceive their peers view agriculture, how their demographics are related to career choice, and if their career choice was changed to a different career upon completion of the study. The study showed a positive relationship between completing an agricultural education class in animal science and interest in going into an agricultural career. Further, females in the study were more likely to choose an agricultural career. After the completion of a school-based agricultural education program, both students and their peers had a more positive outlook on agriculture and its possibilities as a career. Students also increased their career self-efficacy score during the completion of an animal science agricultural education course. They became more confident in their ability to make decisions related to their future career.

A study was conducted to determine the feasibility of concentrating the wastewater of a butter/powder factory for use as an animal feed. Two concentrated products were evaluated: recovered milk product (RMP), which is the direct factory waste stream; and formulated recovered milk product (FRMP), which is a product made by combining RMP and separator de-sludge in a 3:1 ratio. Three pilot scale dryer systems were used to concentrate the product: a spray dryer, a roller dryer, and a pulse combustion dryer. Dried samples were analyzed for fat, moisture, protein, ash, nitrates, chloride, pH, calcium, phosphorus, sodium and amino acids. Values for total digestible nutrients, nitrogen free extract and lactose were calculated. Functional properties were measured by free-fat, insolubility index, wettability, and particle size distribution. Additionally, the microstructure was examined using environmental scanning electron microscopy (ESEM). The objectives to this study were to: 1) further concentrate and dry RMP into a powder to reduce hauling cost, improve consistency, and increase the storage life of the product; 2) add other by-products to the RMP to improve the nutrient profile; and 3) compare three drying systems as to the effect to the nutrient profile, functional properties, and microstructure of the dried product. The protein content in the FRMP was significantly (P<0.05) higher than in the RMP. The nitrate (NO3) concentration in the RMP was significantly (P<0.05) higher than the NO3 concentration in the FRMP. The Mojonnier fat determination test resulted in higher fat content for the products dried on the spray and pulse dryer compared to the Soxhlet fat determination method. The roller drier produced a powder that was significantly (P<0.05) higher in free-fat compared to the other two drier systems. The pulse combustion dryer produced the most soluble product as determined by the insolubility index. The available lysine concentration in the product dried on the roller dryer was significantly (P<0.05) lower than the available lysine concentrations in the product dried on the spray and pulse combustion dryers. The microstructure of the powders was different for each of the dryers when examined using ESEM.

Two experiments were conducted to determine the effects of growth hormone (GH) or melatonin on the reproductive axis of the stallion. In Experiment 1, nine stallions were treated with GH (20 µg/kg BW) or saline for 21 d starting in January. During the last week of treatment, stallions were subjected to low and high dose injections of luteinizing hormone (LH), as well as low and high dose combined injections of gonadotropin releasing hormone (GnRH) and thyrotropin releasing hormone (TRH). Two months after the onset of GH treatment, semen was collected from all stallions every other day for 2 weeks. Treatment with recombinant equine GH increased (P < 0.001) daily IGF-I concentrations, but had no effect (P > 0.1) on concentrations of LH, follicle stimulating hormone (FSH), or testosterone. The testosterone responses to injections of LH were similar (P > 0.1) between treatments. Likewise, the LH, FSH, prolactin, and testosterone responses to the injections of GnRH/TRH were similar (P > 0.1) between groups. Stallions treated with GH exhibited greater volumes of gel-free semen (P < 0.01) and gel (P < 0.05) and had decreased time until ejaculation (P < 0.05). In Experiment 2, nine stallions were given corn syrup containing either melatonin (0.06 mg/kg BW) or nothing for 90 d starting in July. Between d 68 and 75 of treatment, stallions were given injections of LH and combined injections of GnRH and TRH, similar to Experiment I. Semen was collected from all stallions for three days during the last week of treatment. Treated stallions exhibited decreased daily concentrations of prolactin (P < 0.01) and FSH (P < 0.05), and tended to have lower (P = 0.07) LH concentrations for the first 30 d. Testosterone concentrations were similar between groups. In treated stallions, the low dose administration of GnRH/TRH was not as effective (P < 0.01) at increasing plasma concentrations of FSH and testosterone, and the response in plasma prolactin concentrations to a high dose administration of GnRH/TRH was decreased (P < 0.01). Melatonin treatment did not alter seminal characteristics or libido. In conclusion, GH may alter the long-term accessory gland contribution to seminal volume, but does not appear to interact with other constituents of the reproductive axis in the stallion. Long-term melatonin administration decreases plasma concentrations of gonadotropins and prolactin, but the role of melatonin in perturbation of hypothalamic interaction with the pituitary deserves further study.

A series of experiments were conducted to produce transgenic goats by somatic cell nuclear transfer (NT). In all experiments, donor cells were electrically fused to enucleated metaphase II oocytes, then chemically activated. In a preliminary study to evaluate embryonic development following NT with proliferating or quiescent fibroblast or cumulus cells, significantly more embryos reconstructed with quiescent cumulus cells fused (77%) compared with proliferating cumulus cells (41%), proliferating fibroblasts (36%) or quiescent fibroblasts (37%). Improved development to the eight- to sixteen-cell stage was observed when fibroblast cells were serum starved (serum starved 39% vs. serum fed 15%). However, there was no benefit of serum starvation for cumulus cells nor was there a difference among the treatments for development to the blastocyst stage. Next, the in vivo developmental potential of NT embryos produced from the fusion of quiescent transgenic donor cells with cytoplasts prepared from either FSH-stimulated ovaries or nonstimulated abattoir-derived ovaries was compared. There was no difference in the number of transferable embryos produced, nor was there a difference in the number of pregnancies established per recipient between either treatment. All pregnancies from both groups culminated in the births of five healthy female kids. In the third and fourth experiments, proliferating and quiescent donor cells from two different transfected fibroblast cell lines were used to generate cloned goats capable of producing human recombinant antibodies in milk. There was no difference in the number of transferable embryos produced from proliferating donor cells compared with quiescent cells, nor was there a difference in the number of pregnancies established per recipient between either treatment. A twin pregnancy from the quiescent treatment resulted in the birth of two healthy transgenic kids. In the final study, oocytes were harvested either from FSH-stimulated ovaries or from nonstimulated abattoir-derived ovaries to generate transgenic goats by NT using fetal fibroblast cells transfected with the MSP-142 gene. Following transfer of the reconstructed embryos to recipient females, one healthy transgenic kid was produced. There was no effect of oocyte source on the number of pregnancies established or on the number of offspring produced. In total, eight transgenic goats were produced.

An experiment was conducted to determine the effects of dihydrotestosterone (DHT) and estradiol benzoate (EB) given simultaneously on concentrations of FSH and LH and the associated follicular activity, and to monitor the subsequent recovery of the gonadotropes and follicular growth following treatment with either DHT or EB. Twelve mares were assigned to daily treatments of DHT (150 Fg/kg BW) plus EB (22 Fg/kg BW) from d 0 through 30 (Phase I). Beginning on d 31, mares were randomly assigned to one of three treatment groups: 1) oil, 2) DHT (150 Fg/kg BW), or 3) EB (22 Fg/kg BW). On d 30, 44, and 58, GnRH was administered to determine the response of FSH and LH. In phase I, DHT plus EB decreased (P = 0.0001) concentrations of LH and FSH. In phase II (d 31 to 66), DHT decreased (P = 0.0001) LH and FSH concentrations. Estradiol benzoate decreased (P= 0.0001) concentrations of FSH but increased (P = 0.0001) concentrations of LH. There was a significant treatment x day x minute interaction of FSH (P = 0.0001) and LH (P = 0.0002) concentrations in response to administration of GnRH on d 30, 44, and 58. The number of medium follicles (P = 0.0001), large follicles (P = 0.0012) and the size of the largest follicle per day (P = 0.0001) decreased during phase I. During phase II, there was a treatment x day interaction (P = 0.0001) for medium follicles and large follicles. Control mares had more large follicles on d 57 through d 63 whereas EB treated mares had more large follicles on d 45, 49, and 51. Control mares had increased size of the largest follicles at d 57 to 63. Mares in the DHT and EB groups had prolonged (P = 0.01) ovulation intervals as compared with controls. It is concluded that the combination of DHT plus EB suppresses gonadotropin concentrations and the associated follicular activity in mares. Also, concentrations of both gonadotropins must be restored to normal for growth of an ovulatory size follicle and the subsequent ovulation of that follicle.

The first objective of these two studies was to evaluate genetic trends for bulls that have comprised the LSU AgCenter Dean Lee performance bull test for the past 55 years. Data included birth weight (BW), initial weight, 112-day weight, average daily gain (ADG), adjusted yearling weight, and scrotal circumference (SC), on 7,488 yearling bulls of 34 breeds on 112d of test for the last 55 years. The top 4 represented bull breeds with greater than 500 animals (Angus, Charolais, Hereford, and Simmental) were included in this analysis. Analyses revealed that growth traits for all bulls regardless of breed demonstrated a linear increase across the years with BW and SC being the lone exceptions. Birth weight demonstrated a decrease over the years. Hereford and Simmental breeds displayed the greatest decrease in birth weight. For start weight and 112-day weight, Simmental and Angus exhibited the greatest increase in weight over the years. Adjusted yearling weight had the greatest increase in the Simmental breed. Simmental breed exhibited the greatest decrease for SC over the years. The second objective was to test the association of single nucleotide polymorphisms (SNPs) on three candidate genes calpastatin (CAST), somatotropin (GH1), and insulin-like growth factor 1 (IGF-1) with growth and performance traits in bulls participating in a forage based performance bull test. Of the 49 SNP genotyped, 20 were chosen for CAST, 9 for GH1, and 20 for IGF-1. These SNP were genotyped on 47 purebred Angus, Braford, and Brahman bulls against traits including average daily gain, birth weight, weaning weight, initial weight, final weight, hip height, backfat (BF), intramuscular fat %, ribeye area (REA), and scrotal circumference (SC). The mixed model procedure of SAS was utilized to evaluate associations of the 49 SNPs and measured traits. Insulin-like growth factor 1 markers (rs133980322, rs137651874, rs132665612, rs132951819, rs110959643, rs109022910, rs110266103, rs109199979 and rs109327701) were determined to be associated with growth and performance traits, including weaning weight, initial weight, final weight, average daily gain, backfat, intramuscular fat %, hip height and scrotal circumference. GH1 marker rs10927590 was significantly associated with weaning weight, initial weight, and final weight.