<p> Silvopasture, the sustainable integration of livestock and trees on the same unit of land, may have the potential to contribute to agricultural productivity in the Northeastern United States and concurrently encourage the ecosystems services which trees provide. Extremely little is known regarding the ecological characteristics of silvopastures being utilized, their social and economic drivers, or their agricultural productivity. Silvopasture characteristics, management, and reasons for use were documented through a purposeful sample of silvopasture practitioners in New York and New England. Results document the functional role of silvopastures on regional farms. This research also investigated the ecological and production dynamics of silvopastures in the Northeastern United States, their management, and the reasons for their use. Forest conversion to silvopasture, open pasture, and heavily thinned forests were utilized to investigate the ecological and production dynamics during the establishment phase of forest conversion to pasture. Results suggest the potential for silvopasture as a competitive management option for forestland. This dissertation establishes a baseline for future investigations into the management of silvopastures in the Northeastern United States.</p>

<p> Resistance to synthetic anthelmintics has become a worldwide threat to various livestock species. The use of nutraceuticals and livestock management practices is being explored as an alternative to this issue. Foods containing a high amount of tannins are known to decrease gastrointestinal parasite infection. It is known that goats self-medicate by ingesting tannin-rich feed mixtures that they often avoid (Villalba et al. 2010). Studies have offered animals a particular mixture of feed that is known to be medicinal to decrease a parasite burden. In this study, we offered a tannin-rich plant in a concentrated pellet form so it could be more applicable to livestock management practices. We addressed our issue by using 20 kids that were separated into two groups. One group was dosed with parasites, PK, and another group was not dosed with parasites, NPK. These kids were observed in a 30-day experiment to determine if they dosed themselves efficiently with a tannin-rich plant, sericea lespedeza, Lespedeza cuneata, when the need arose. Each group was conditioned and given preference tests between alfalfa, a feed they were familiar with, and sericea lespedeza, the tannin-rich feed. Fecal samples (FEC) were taken periodically to monitor the eggs per gram of the gastrointestinal nematode, Haemonchus contortus. Eggs per gram decreased in the parasitized group throughout the experiment. The parasitized group was found to be self-medicating with the correct doses of sericea lespedeza specialized to their internal needs after they were conditioned, whereas there were no significant results that the non-parasitized group chose sericea lespedeza over alfalfa.</p>

<p> Two evaluations were conducted to evaluate the biological and economic production efficiency of retaining replacement females in a straight-bred Angus herd (HR) as opposed to purchasing crossbred replacements for a terminal sire production system (PR) where maximum maternal and individual heterosis is achieved. The first study was a comparison of the HR system versus PR system. It was modeled after a 100 hd, straight-bred Angus cowherd that raises their own replacement females. The (NASEM, 2016) model was used to determine the required metabolizable energy (ME)/animal for each stage of production. Stages were broken into segments including weaning &ndash; d 28, d 29 &ndash; breeding, breeding &ndash; mid-gestation. It was determined, that on the same ME resources, an operator can run 117 cows and produce 7,833 more kilograms in the PR system compared to the 100 cows in the HR system. Economically, the PR system produced $10,949 more dollars of net income than the HR system. In the second study, 25 Angus and 29 SimAngus heifers were placed in the South Dakota State University Cow Calf Education and Research Facility Insentec feeding system, where they were evaluated for dry matter intake, average daily gain, gain:feed, metabolizable energy intake, predicted dry matter intake, and residual feed intake based on NRC prediction equations. At the start of the trial there was no difference in initial BW. The first period (d 1 - 98) featured no difference in BW, DMI, G:F, ME intake, predicted DMI or RFI_NRC. However, Angus heifers exhibited a greater ADG (<i>P</i> &le; 0.02) than SimAngus heifers. During period 2 (d 99 - 167), heifer BW, G:F, and RFI_NRC were not different between breeds; however, Angus heifers had a greater ADG (<i> P</i> &le; 0.02), DMI (<i>P</i> &lt; 0.01), ME intake (<i> P</i> &lt;0.01) and predicted DMI (<i>P</i> &le; 0.04). Cumulatively (d 1 - 167) Angus heifers had greater ADG (<i>P</i> &lt; 0.01), DMI (<i>P</i> &le; 0.03), G:F (<i>P</i> &le; 0.05), ME intake (<i>P</i> &le; 0.03), and tended to have greater predicted DMI (<i>P</i> &le; 0.06) than SimAngus heifers, but no difference was observed in RFINRC. Contrary to our initial assumptions, these results show that in this herd, Angus heifers have the advantage in performance, feed intake and efficiency over SimAngus heifers. These results warrant further research with a larger sample size and greater genetic diversity, in order to draw compelling conclusions that explain these biological differences. </p><p>

<p> <i>Salmonella</i> is a major foodborne pathogen around the world and chickens are the major reservoir to transmit <i>Salmonella </i> into the human food chain. For decreasing the infection of <i> Salmonella,</i> we developed six attenuated live vaccines based on <i> Salmonella</i> Enteritidis (SE) and Typhimurium (ST) for testing the cross-serovar and cross-serogroup protection from the challenge of <i> Salmonella</i> Heidelberg and <i>Campylobacter jejuni.</i> One of the constructed vaccine strain showed ability to protect against challenge from <i>Salmonella</i> Heidelberg. Even though some preventive approaches are able to decrease <i>Salmonella</i> colonization in the gastrointestinal tract of chickens or other farm animals, <i>Salmonella</i> transmission mechanisms remain unclear. For analyzing <i>Salmonella</i> transmission routes and dynamics, we designed a series of <i>Salmonella</i> isogenic barcode-tagged strains by inserting six random nucleotides into a functionally neutral region on the chromosome of <i>Salmonella</i> Enteritidis. These barcode-tagged strains can be used as a tool for quantitative tracking of <i>Salmonella</i> transmission in the chicken flock by profiling the barcode regions using high-throughput sequencing. The efficiency of this novel approach has been estimated by chicken experiments and can be applied for further studies about <i>Salmonella</i> transmission and population dynamics. Due to the increasing pressure of using antibiotics as the growth promoter in the farm animals, probiotics is a suitable alternative to replace antibiotics by providing beneficial effects, such as promotion of animal health, decreased infection by pathogens, and improval of growth performance in poultry. In this study, 90 probiotic candidate strains were isolated and evaluated for decreasing the gut permeability in Caco-2 cell lines. The result from animal experiments indicated that a combined batch culture of 3 selected strains showed significant efficacy in controlling intestinal colonization of ST in neonatal turkey poults.</p><p>

<p> Although swine diseases and parasites cause significant losses to producers in Hawai&lsquo;i, limited information is available on changing disease patterns and related farm practices. The objectives of this study were to identify practices used on Hawai&lsquo;i swine farms and to determine if there is a relationship between those practices and the absence or presence of a disease. A management and biosecurity practices survey was administered to farmers (n = 27). Survey questions were analyzed by region, sow population, and disease presence. Most common practices included cooking food waste (94% of farmers feeding food waste), feral pig exclusion (74%), and administering an anthelmintic (63%). Challenges faced by farmers include biosecurity concerns of on-farm sales, limited access to veterinary specialists, and excluding vermin from the production area. In addition, serological samples (n = 414) from swine farms (n = 57 out of 200 farms) were tested and found positive for antibodies against Porcine Circovirus Type 2b (PCV ELISA; 98% positive), Senecavirus (SVA IFA; 58%), Porcine Epidemic Diarrhea (PED IFA; 33%) and Porcine Reproductive and Respiratory Syndrome (PRRS ELISA; 16%). Fecal flotation detected coccidia oocysts (63%) on every island; Oesophagostomum dentatum (26%), Ascaris suum (18%), Strongyloides (11%), Metastrongylus spp. (8%), and Trichuris suis (8%) ova were on a subset of islands. Analysis indicates that disease prevalence is regionally distributed. Kaua&lsquo;i, which is protected by a quarantine order, has remained negative for PED, and Moloka&lsquo;i, which sees less interisland traffic, is negative for PRRS, PED, and SVA. Geographical patterns in disease distribution assist biosecurity and management practice recommendations, the design of vaccination protocols, and the judicious use of antibiotics.</p><p>

<p> Finding ways to objectively measure welfare within different sectors of the beef industry is necessary to continually improve cattle welfare from birth to slaughter. The first objective of Study 1 was to benchmark cow-calf producer perspectives on management strategies and challenges that ultimately affect cattle welfare on ranches in the United States. The second objective of Study 1 was to quantify how producers are marketing their calf crop, their priorities when selecting replacements, and if producers saw value in handling and care guidelines. A total of 1,414 responses from cow-calf producers in 44 states were collected through a survey done in partnership with <i> BEEF</i> Magazine. Thirty questions were asked of producers to gather demographic information, producers&rsquo; current handling and health management practices, and how they prioritized industry challenges. As well as establish at what age and through what avenue producers are marketing their calf crop, and gauge producer perspectives on a quality assessment outlining handling and care guidelines.</p><p> After analyses of producer responses, it was concluded that the frequency of management methods and decisions are impacted by age, operation size, location, and BQA certification. A higher percentage of respondents who were BQA certified used electronic eartags, followed by freeze branding. A higher percentage of respondents not BQA certified used basic eartags and hot branding. 74.5% of respondents were preconditioning their calf crop. A higher percentage of respondents were preconditioning their calf crop that were BQA certified, than those who were not BQA certified. The most important beef industry challenge identified was cow-calf health and the biggest challenge to producer&rsquo;s own operation was identified as land availability/price. The most important animal health issues on producers&rsquo; operations were identified as Bovine Respiratory Disease, flies, Pinkeye, and reproductive health. By producer age, calf/neonate health was identified as the biggest challenge for respondents under the age of 30. Respondents age 55-70 responded that Veterinary Feed Directive (VFD)/regulations was more of a challenge than any other age group. Respondents with 50 head or less or more than 1,000 head more frequently retained their calf crop through finishing and respondents with 51 to 200 head and 201 head to 500 head more frequently backgrounded and then sold their calf crop. 13.5% of respondents answered yes, a veterinarian had offered to administer a drug for pain management when castrating or dehorning. Of those 13.5% who responded yes pain management had been offered, 54.55% of respondents chose to use a pain relief method. A higher percentage of producers that precondition also indicated that they use a pain relief method when castrating or dehorning more frequently, though it was still a low percentage. Overall, 46.3% of respondents saw value in handling and care guidelines and 54.9% of respondents saw value in a program including source and age verification, a vaccination plan, and handling and care guidelines. Respondents who were BQA certified, had a beef cow inventory of 501 to 1,000 head, who preconditioned their calves and backgrounded them before selling, and who lived in the West more frequently saw value in a quality assessment outlining handling and care guidelines.</p><p> The objective of Study 2 was to examine the effects of captive bolt length and breed type on post-stun leg activity in cattle. A total of 2,850 Holstein (HOL) and non-Holstein British/Continental bred (NHOL) steers and heifers were observed post-stunning at a large commercial slaughter facility. A penetrating pneumatic captive bolt stunner was used with three different bolt lengths: CON, 15.24 cm; MED, 16.51 cm; and LON, 17.78 cm. Hind limb kicking, forelimb activity, take away belt stops, carcass swing and number of knife sticks during exsanguination were recorded for each animal from video recording. Hind limb and forelimb kicks observed ranged from 0 to 25 and 0 to 8, respectively. A significant main effect of treatment, breed type and an interaction between treatment and breed type on hind limb activity was found. Analysis of post-stun hind limb and forelimb activity indicated that increasing pneumatic captive bolt length does not decrease post-stun leg activity but alternatively can increase kicking when using the longest bolt tested in particular types of cattle, i.e. Holsteins. Other parameters associated with the shackling and hoisting process were impacted by breed type as well. There was a higher percentage of cattle experiencing take away belt stops and carcass swing in HOL as compared with NHOL. (Abstract shortened by ProQuest.)</p><p>