Several studies suggest that the administration of GnRH near the time of insemination improves pregnancy rates in cattle. It has also been reported that there is greater improvement in repeat-breeder animals than at first service. The mechanism for this observation has not been established. Twenty-eight lactating Holstein cows that returned to estrus after one or more inseminations from the usu caine Dairy were used in the study. Anilrals were rarxiomly divide:i into tW'O treatment groups, intrarmJscular administration of 100 ug GnRH or saline oontrol at the tirre of insemination. Blood samples were collected at o, 1, 1.5, 2, 2.5, 3 and 4 hours post-insemination for LH determination and on days 0 through 7, 10, 16 and 22 for progesterone determination. Pregnancy status was detennined by rectal palpation 40 to 47 days post insemination. serum IR concentrations reached peak concentrations (9.33 ± 5.5 ng/ml) by one hour following GnRH administration. This was significantly different from saline controls (p Serum progesterone levels increased as expected. from day o to day 16 in all animals. Animals treated with GnRH that became pregnant tended to have the highest progesterone levels beginning from day 4. Animals treated with GnRH that were non-pregnant at 40 to 47 days tended to have the lowest progesterone levels from days 4 through 10 but were high on day 16. Pregnant animals had higher progesterone levels than non-pregnant animals from days 4 to 16. These differences approached significance (0.25 > p < 0.10). These results support the contention that GnRH administration affects progesterone levels rut do not conclusively establish increased early progesterone levels as the mechanism for improved pregnancy rates. Other hormonal andl functional factors may be involved.

Distributed Shared Memory (DSM) provides programmers with a shared memory environment in systems where memory is not physically shared. Clusters of Workstations (COWs), an often untapped source of computing power, are characterised by a very low cost/performance ratio. The combination of Clusters of Workstations (COWs) with DSM provides an environment in which the programmer can use the well known approaches and methods of programming for physically shared memory systems and parallel processing can be carried out to make full use of the computing power and cost advantages of the COW. The aim of this research is to synthesise and develop a distributed shared memory system as an integral part of an operating system in order to provide application programmers with a convenient environment in which the development and execution of parallel applications can be done easily and efficiently, and which does this in a transparent manner. Furthermore, in order to satisfy our challenging design requirements we want to demonstrate that the operating system into which the DSM system is integrated should be a distributed operating system. In this thesis a study into the synthesis of a DSM system within a microkernel and client-server based distributed operating system which uses both strict and weak consistency models, with a write-invalidate and write-update based approach for consistency maintenance is reported. Furthermore a unique automatic initialisation system which allows the programmer to start the parallel execution of a group of processes with a single library call is reported. The number and location of these processes are determined by the operating system based on system load information. The DSM system proposed has a novel approach in that it provides programmers with a complete programming environment in which they are easily able to develop and run their code or indeed run existing shared memory code. A set of demanding DSM system design requirements are presented and the incentives for the placement of the DSM system with a distributed operating system and in particular in the memory management server have been reported. The new DSM system concentrated on an event-driven set of cooperating and distributed entities, and a detailed description of the events and reactions to these events that make up the operation of the DSM system is then presented. This is followed by a pseudocode form of the detailed design of the main modules and activities of the primitives used in the proposed DSM system. Quantitative results of performance tests and qualitative results showing the ease of programming and use of the RHODOS DSM system are reported. A study of five different application is given and the results of tests carried out on these applications together with a discussion of the results are given. A discussion of how RHODOS’ DSM allows programmers to write shared memory code in an easy to use and familiar environment and a comparative evaluation of RHODOS DSM with other DSM systems is presented. In particular, the ease of use and transparency of the DSM system have been demonstrated through the description of the ease with which a moderately inexperienced undergraduate programmer was able to convert, write and run applications for the testing of the DSM system. Furthermore, the description of the tests performed using physically shared memory shows that the latter is indistinguishable from distributed shared memory; this is further evidence that the DSM system is fully transparent. This study clearly demonstrates that the aim of the research has been achieved; it is possible to develop a programmer friendly and efficient DSM system fully integrated within a distributed operating system. It is clear from this research that client-server and microkernel based distributed operating system integrated DSM makes shared memory operations transparent and almost completely removes the involvement of the programmer beyond classical activities needed to deal with shared memory. The conclusion can be drawn that DSM, when implemented within a client-server and microkernel based distributed operating system, is one of the most encouraging approaches to parallel processing since it guarantees performance improvements with minimal programmer involvement.

Endophytic fungi (A. coenophialum and A. lolii) which infect grasses produce ergot alkaloids that serve as the grasses' chemical defenses and enhance the vigor of the grass. Turf-type tall fescue with high endophyte levels has been deliberately developed to produce a greener, more vigorous, pest-resistant turf. Consumption of endophyte-infected grass causes various toxicity symptoms in livestock. Cattle in the southeastern and midwestern United States, where tall fescue is grown on 14 million hectares, often develop signs of toxicosis during summer months from grazing plants in fected by A. coenophialum. A more severe form of the disease, fescue foot, has been associated with cold environment and reported in late fall and winter months not only in the southeastern United States but also in the northwest United States. In New Zealand, where perennial ryegrass is grown on 7 million hectares of pasture, sheep often develop a condition called ryegrass staggers from grazing plants infected by A. lolii. New Zealand reports economic losses grazing plants infected by A. lolii. New Zealand reports economic losses associated with the sheep industry of $205 million per year. In the United States, economic losses associated with the beef cattle industry alone is estimated at $600 million per year. Range finding experiments and case studies of fescue foot and perennial ryegrass staggers (PRGS) were conducted on cattle and sheep under grazing and barn conditions. The main objective was to determine threshold levels of the endophyte toxins, ergovaline (EV) (appendix 1) and lolitrem B (appendix 2), associated with the diseases of fescue foot and PRGS respectively. Fescue foot was experimentally induced in cattle under barn studies in the spring with 825 ppb ergovaline. The ergovaline contaminated feed was given for a period of 42 days. Similar barn studies in sheep in spring to early summer did not produce clinical fescue foot with up to 1215 ppb. Field studies of natural fescue foot in a herd of sheep were conducted, (ie 540 ppb) values of ergovaline in the feed, but clinical disease was not produced in late fall through winter. A case study from a herd of sheep revealed 813 ppb dietary ergovaline had produced fescue foot in the months of fall (November). Fields of perennial ryegrass (PRG) where sheep received 2,135 ppb lolitrem B toxin were associated with clinical cases of PRGS in 42 sheep of 237 sheep (18 percent incidence rate) in the Willamette Valley of Oregon. Three months later, sheep on this same field which then had 1,465 ppb lolitrem B, did not have PRGS. These were the first range finding experiments undertaken in this locale to document threshold levels of endophyte toxins associated with fescue foot and PRGS. / Graduation date: 1994

Three experiments were conducted to determine the effects of supplementing wheat-based dry distillers grains with solubles (DDGS) on cow performance, forage utilization, and production costs. In the first two experiments, 48 dry, pregnant Black Angus cows (mean BW±SD; 598.2±4.2 kg) stratified by body weight (BW) and days pregnant were allocated randomly to one of three replicated (n=2) treatments. Cows were managed on stockpiled crested wheatgrass pasture (TDN=49.0, CP=7.3 (% DM)) in experiment one (EXP 1) and barley straw-chaff residue (TDN=45.4, CP=8.6 (% DM)) in experiment two (EXP 2). EXP 1 supplement treatments were (1) 100% DDGS (70:30 wheat:corn blend; DDGS); (2) 100% commercial supplement (COMM); or (3) control no supplement (CONT). EXP 2 supplement treatments were (1) 100% DDGS (70:30 wheat:corn blend; DDGS); (2) 50% DDGS + 50% rolled barley (50:50); or (3) 100% rolled barley grain (control; BARL). Forage utilization was measured for both trials using the herbage weight disappearance method. Cow BW, body condition score (BCS), and rib and rump fat were measured at the start and end of trial and cow BW was corrected for conceptus gain based on calving data. There was no effect (P > 0.05) of treatment on forage utilization in either experiment. In EXP 1, cow performance was not affected (P > 0.05) by supplement strategy. In EXP 2, BW change was 11.3, 6.8, and -6.5 (P < 0.01) for DDGS, 50:50, and BARL, respectively. Because forage utilization was not affected, the difference in cow BW was the result of supplement type. Costs per cow per day in EXP 1 were $0.66, $0.68, and $0.60 for DDGS, COMM, and CONT, respectively. In EXP 2, costs per cow per day were $0.79, $0.80, and $0.80 for DDGS, 50:50, and BARL treatments, respectively.<p> In experiment three (EXP 3), four ruminally cannulated beef heifers were individually fed a basal ration of 75% ground barley straw and 25% ground grass hay (TDN=46.3, CP=7.5 (% DM)). Heifers were supplemented with either (1) DDGS (70:30 wheat:corn blend; DDGS); (2) commercial range pellet (COMM); (3) barley grain and canola meal (BAR+CM); or (4) control no supplement (CONT). Forage intake, apparent total tract digestibility, and passage rate; rumen fermentation parameters; and the rate and extent of forage degradation were measured. Forage intake, passage rate, and apparent total tract digestibility of DM, NDF, and ADF were not affected (P > 0.41) by treatment. Apparent total tract digestibility of CP was increased (P = 0.02) by supplementation, but was not different between DDGS, COMM, and BAR+CM treatments. Ruminal pH was not affected (P = 0.20) by treatment diet, but rumen ammonia-N was increased (P < 0.01) by supplementation. The potentially degradable and undegradable forage fractions were affected (P < 0.02) by supplementation, reducing the extent of forage degradation. Also, there was a tendency (P = 0.06) for the rate of forage DM degradation to increase when supplements were fed. The results of these experiments indicate that wheat-based DDGS can be used as a supplement for beef cows consuming forages with similar or greater effects compared to a commercial pellet and barley grain. DDGS had similar effects on rumen metabolism as the commercial range pellet or barley grain and canola meal, suggesting DDGS can be substituted on a unit basis with these supplements. As such, the inclusion of wheat-based DDGS as a supplement for beef cows will depend on the initial price of the supplement.

Three experiments were conducted to determine the effects of supplementing wheat-based dry distillers grains with solubles (DDGS) on cow performance, forage utilization, and production costs. In the first two experiments, 48 dry, pregnant Black Angus cows (mean BW±SD; 598.2±4.2 kg) stratified by body weight (BW) and days pregnant were allocated randomly to one of three replicated (n=2) treatments. Cows were managed on stockpiled crested wheatgrass pasture (TDN=49.0, CP=7.3 (% DM)) in experiment one (EXP 1) and barley straw-chaff residue (TDN=45.4, CP=8.6 (% DM)) in experiment two (EXP 2). EXP 1 supplement treatments were (1) 100% DDGS (70:30 wheat:corn blend; DDGS); (2) 100% commercial supplement (COMM); or (3) control no supplement (CONT). EXP 2 supplement treatments were (1) 100% DDGS (70:30 wheat:corn blend; DDGS); (2) 50% DDGS + 50% rolled barley (50:50); or (3) 100% rolled barley grain (control; BARL). Forage utilization was measured for both trials using the herbage weight disappearance method. Cow BW, body condition score (BCS), and rib and rump fat were measured at the start and end of trial and cow BW was corrected for conceptus gain based on calving data. There was no effect (P > 0.05) of treatment on forage utilization in either experiment. In EXP 1, cow performance was not affected (P > 0.05) by supplement strategy. In EXP 2, BW change was 11.3, 6.8, and -6.5 (P < 0.01) for DDGS, 50:50, and BARL, respectively. Because forage utilization was not affected, the difference in cow BW was the result of supplement type. Costs per cow per day in EXP 1 were $0.66, $0.68, and $0.60 for DDGS, COMM, and CONT, respectively. In EXP 2, costs per cow per day were $0.79, $0.80, and $0.80 for DDGS, 50:50, and BARL treatments, respectively.<p> In experiment three (EXP 3), four ruminally cannulated beef heifers were individually fed a basal ration of 75% ground barley straw and 25% ground grass hay (TDN=46.3, CP=7.5 (% DM)). Heifers were supplemented with either (1) DDGS (70:30 wheat:corn blend; DDGS); (2) commercial range pellet (COMM); (3) barley grain and canola meal (BAR+CM); or (4) control no supplement (CONT). Forage intake, apparent total tract digestibility, and passage rate; rumen fermentation parameters; and the rate and extent of forage degradation were measured. Forage intake, passage rate, and apparent total tract digestibility of DM, NDF, and ADF were not affected (P > 0.41) by treatment. Apparent total tract digestibility of CP was increased (P = 0.02) by supplementation, but was not different between DDGS, COMM, and BAR+CM treatments. Ruminal pH was not affected (P = 0.20) by treatment diet, but rumen ammonia-N was increased (P < 0.01) by supplementation. The potentially degradable and undegradable forage fractions were affected (P < 0.02) by supplementation, reducing the extent of forage degradation. Also, there was a tendency (P = 0.06) for the rate of forage DM degradation to increase when supplements were fed. The results of these experiments indicate that wheat-based DDGS can be used as a supplement for beef cows consuming forages with similar or greater effects compared to a commercial pellet and barley grain. DDGS had similar effects on rumen metabolism as the commercial range pellet or barley grain and canola meal, suggesting DDGS can be substituted on a unit basis with these supplements. As such, the inclusion of wheat-based DDGS as a supplement for beef cows will depend on the initial price of the supplement.

La valutazione oggettiva del benessere negli allevamenti di bovine da latte, risulta peraltro molto complessa e controversa. I principali problemi riguardano la scelta degli indicatori da utilizzare nel modello e l’aggregazione dei risultati ottenuti con ciascun indicatore in un punteggio globale che sia espressione del benessere reale. Alla luce di queste considerazioni, è evidente che un modello applicativo di valutazione del benessere necessita di una validazione scientifica. I nostri risultati hanno mostrato che sono soprattutto i valori di fruttosamina riscontrati fra la 3a e la 5a settimana di lattazione quelli che maggiormente riflettono la glicemia media delle settimane precedenti, quindi l’entità del deficit energetico e della riduzione delle condizioni nutrizionali degli animali Nella valutazione del benessere animale un altro aspetto fondamentale è rappresentato dall’individuazione di un eventuale status di stress cronico, ricorrendo ad esempio alla cortisolemia plasmatica. Tra gli indicatori di tipo fisiologico che sono sembrati molto importanti per la validazione dei modelli di valutazione del benessere animale, troviamo i parametri relativi a fatti infettivo-infiammatori (proteine positive della fase acuta, tra cui si ricordano l’aptoglobina e la ceruloplasmina, e quelle negative, specialmente le albumine e il colesterolo). Viceversa, l’utilizzo contemporaneo di una serie di indicatori di tipo biochimico-fisiologico, potrebbe fornire indicazioni per una valutazione più completa dei diversi aspetti del benessere. Ciò al fine di accertare se i suddetti parametri possano fungere da indicatori “assoluti” per ottenere indicazioni più oggettive delle reali condizioni di benessere/malessere degli animali allevati, costituendo pertanto un valido “riferimento” per i modelli di campo. Le informazioni prodotte con questo tipo di analisi possono fornire utili indicazioni sia in termini teorici di validazione del benessere (soprattutto per meglio precisare i vari aspetti che lo compongono e che confluiscono nel benessere globale) e sia in termini applicativi di miglior ridefinizione dei pesi relativi con cui aggregare i diversi aspetti del benessere nel modello di campo. Altri parametri fisiologici utilizzati come riferimento, e risultati molto importanti, sono il cortisolo e la fruttosamina. In particolare, i risultati ottenuti con questo approccio multivariato, applicato ai parametri biochimico-fisiologici hanno mostrato un parziale accordo fra la valutazione del benessere ottenuta con il modello SDIB. / The objective assessment of lactating dairy cows welfare is complex and controversial. The main concerns are the choice of the model indicators and the aggregation of obtained results in a global score that represents the effective welfare. According to these considerations, the animal welfare determination needs a scientific validation. Our results shows that the value of fructosamine between the third and fifth week in lactation strongly reflects the average blood glucose in the previous weeks, therefore it shows the energetic deficit and the low nutritional status. The determination of chronic stress is also fundamental to determine the animal welfare, it can be measured by the plasmatic cortisolemic value. Some indicators of inflammators-infective stress, such as the positive proteins of acute phase (aptoglobins and ceruloplasmin) and the negative ones (albumins and cholesterol) are some of the best physiological indicators capable of validating the determination of animal welfare. On the contrary, the contemporary utilisation of different biochemical-physiological indicators could give more comprehensive determination of animal welfare. The latter could be used as “absolute” indicators to obtain more objective indications of the real conditions of breeding animals' welfare, therefore, being a valid “reference” for field models. These kind of analysis can give useful theorical indication to validate the welfare (above all considering the global view of it), and also in practical applications capable of defining the relative scores aggregating several aspects of welfare in field models. Also cortisol and fructosamine are very important physiological indicators. Particularly, the results obtained by this multivariate approach, which was applied to biochemical and physiological parameters, showed partial agreement between the welfare evaluation by SDIB model.

Thesis (M.S.)--Mississippi State University. Department of Animal and Dairy Sciences. / Title from title screen. Includes bibliographical references.

Diss. (sammanfattning) SLU : Sveriges lantbruksuniv., 2009. / Härtill 4 uppsatser.

Einleitung: L-Carnitin spielt eine zentrale Rolle im Energiestoffwechsel. Da dieser in der Frühlaktation bei Hochleistungskühen besonders beansprucht und z.T. überlastet wird, ergibt sich die Frage, ob durch L-Carnitinsupplementation ein stabilerer Stoffwechsel und damit bessere Leistungen erreicht werden können. Zielstellung: Es wurde geprüft, ob bei Hochleistungskühen mit einer mittleren Milchleistung von 12000 kg/Jahr die orale Supplementation von L Carnitin im peripartalem Zeitraum bei zwei verschiedenen Applikationszeiträumen Stoffwechsel-, Leistungs- und Gesundheitsverbesserung erbringt. Versuchsanordnung: Aus einer Gesamtherde von 322 Kühen wurden 81 Tiere randomisiert auf vier Gruppen aufgeteilt. Zwei dieser Gruppen erhielten L-Carnitin (Supplementationsgruppen) und die anderen zwei Gruppen stellten die Kontrollgruppen (KG 1 n = 14/ KG 2 n = 11) dar. Von den supplementierten Gruppen erhielt Car. 1 (n = 26) von 3 Wochen (Wo.) ante partum (a.p.) bis zur Kalbung über das Futter täglich 5g L Carnitin (Carnipas®). Post partum bekamen die Tiere 1g L Carnitin von der Kalbung bis vier Wo. p.p. Parallel wurden einer zweiten supplementierten Gruppe, Car. 2 (n = 30), täglich 5g L Carnitin 3 Wochen a.p. bis zur Kalbung verabreicht. Klinische und Blutkontrollen erfolgten 28 Tage (d) a.p., drei d p.p, 28 d p.p. sowie 56 d p.p. Es wurden das Gesamtcarnitin (GC, n = 5), das freie Carnitin (FC, n = 5), Carnitinester (CE, n = 5), FFS, BHB, Bilirubin, Glucose, Cholesterol, Harnstoff, TTP, Albumin, CK, AST, Pi, Ca, Fe bei allen Tieren analysiert. Zusätzlich erfolgte die Erfassung der Laktationsleistung, der Milchinhaltsstoffe, der Rastzeit (RZ), der Zwischentragezeit (ZTZ) und der Morbidität. Ergebnisse: Das GC, FC und die CE besitzen in den supplementierten Gruppen Car 1 drei d p.p. höhere Konzentrationen als die Kontrollgruppen, die bei Car. 2 (p < 0,05) im GC und FC auch im weiteren Verlauf beobachtet wurden. Ein deutlicher Konzentrationsabfall aller L-Carnitinfraktionen vier Wo. p.p. wurde in den supplementierten Gruppen beobachtet. In den Kontrollgruppen stiegen sie zur gleichen Zeit nicht einheitlich an. Acht Wochen p.p. sanken die L-Carnitinkonzentrationen im Blut sowohl in den Kontrollgruppen, als auch in der supplementierten Gruppen weiter ab. In allen Gruppen stiegen drei d p.p. die FFS-Konzentrationen an (p < 0,05), das BHB auch in den supplementierten Gruppen, die Glucose- und Cholesterolkonzentration fielen ab (p < 0,05). Vier und 8 Wo. p.p. ließen sich ein Abfallen der FFS- (p < 0,05) und der BHB-Konzentrationen (p < 0,05) erkennen. Die Cholesterol- (p < 0,05) und verzögert auch die Glucosekonzentration stiegen an. Drei d p.p. stiegen die Bilirubinkonzentration (p < 0,05) und die AST-Aktivität (p < 0,05) an, dem ein ebensolcher Abfall (p < 0,05) folgte. Präpartal trat in der supplementierten Gruppen Car. 2 eine höhere Bilirubinkonzentration als in der Kontrollgruppe (p < 0,05) auf, was bei den AST-Aktivitäten zwischen den supplementierten Gruppen postpartal (p < 0,05) der Fall war. Drei d p.p waren niedrigere Konzentrationen des Proteins (p < 0,05), des Albumins (p < 0,05) in Car. 2 und in der Kontrollgruppe sowie des Harnstoffs (p < 0,05) in den Kontrollgruppen zu beobachten. Die CK-Aktivität nahm drei d p.p. zu (p < 0,05), um vier Wo. p.p. wieder abzufallen (p < 0,05). Gleichzeitig war einen Anstieg des Proteins (p < 0,05) und des Albumins in den Kontrollgruppen (p < 0,05), verzögert auch in den supplementierten Gruppen (p < 0,05), messbar. In allen Gruppen waren drei d p.p. niedrigere Ca- (p < 0,05), Fe- (p < 0,05) und Pi- Konzentrationen (p < 0,05) auffällig, die später wieder anstiegen. Im Verlauf war die Ca-Konzentration bei Car. 2 gegenüber der Kontrollgruppe höher (p < 0,05). Die Leistungsparameter differierten weder bei den Milchleistungs-, noch bei den Fruchtbarkeitskennzahlen gesichert. Bezüglich der Morbidität war auffällig, dass das GC und FC bei gesunden Kühen a.p. gegenüber den im Laktationsverlauf erkrankten gesichert höher war (p < 0,05). Schlussfolgerungen: Orale L Carnitinapplikation bei Kühen mit hohem Milchleistungsniveau erbrachte keine Stoffwechsel-, Leistungs- und Morbiditätsunterschiede gegenüber den Kontrollgruppen. Die Ergebnisse entsprechen aber der Hypothese einer gesteigerten ß-Oxidation durch die Carnitinsupplementation mit erhöhten BHB-Konzentrationen als Folge. Post partum gesunde Kühe hatten a.p. signifikant höhere L-Carnitinkonzentrationen als kranke.

This dissertation evaluated nutritional approaches such as the addition of betaine, prebiotics, probiotics, transitional metabolic substrates, and β-mercaptoacetate (MAA; a compound which inhibits β-oxidation) to the diet of lactating dairy cows to determine their impact on physiological, metabolic, hormonal and production responses during thermal stress. The first objective was to evaluate the use of an organic osmolyte, betaine to reduce the impact of heat stress (HS). Cows were fed either 0 (control; CON), 57 mg/kg BW (mid) or 114 mg/kg (high; HI) body weight (BW) betaine and subjected to thermoneutral (TN) and HS conditions. There was an increase in milk yield during TN with HI betaine over controls (P< 0.01), but the advantage was lost during HS. Plasma glucose increased during HS in HI dose cows compared to control (P < 0.01) as did plasma insulin (P = 0.01). Betaine increased milk production during TN and plasma glucose in HS, but did not improve the HS response. Objective two evaluated the use of a probiotic or direct fed microbial (DFM), Calsporin (Bacillus subtilus C-3102) to decrease the effects of HS in dairy cows. We hypothesized that feeding Calsporin prior to and during HS would reduce pathogenic strains of bacteria, maintain commensal microbes, and improve ruminal anaerobic fermentation resulting in improved milk yield (MY). Milk yield was numerically increased (1.26 kg, P = 0.11) in cows fed Calsporin during TN but was reduced under HS (-2.67 kg, P < 0.01) and milk protein content was decreased (P = 0.05). The DFM tended to decrease somatic cell count (SCC) across periods (P = 0.07). Calsporin addition to the diet did not affect respiration rates and was associated with higher rectal temperature at 1800 in HS (P = 0.02). The expression of heat shock protein 27 (HSP27) was decreased with Calsporin treatment (P = 0.03) and in both HS and TN. The fecal microbial count did not change with the exception of the Calsporin strain in treated animals (P < 0.01). The third objective was to feed OmniGen-AF (OG) to dairy cows before and during thermal stress. We hypothesized that feeding OG to HS dairy cows will improve the immune response, and decrease production losses associated with HS. Cows fed OG maintained lower SCC compared to control (P < 0.01) during the recovery period. We did not detect differences between groups in serum calcium while serum non-esterified fatty acid (NEFA) concentrations (P = 0.10) tended to be greater in OG fed cows across the Agricultural Research Center (ARC) portion including HS. Serum Adrenocorticotropic hormone (ACTH) levels were greater in OG cows (P<0.0001) across all sample days. Feeding OG reduced the HS response including serum Cortisol. The final study measured the effects of the metabolic substrate β-hydroxybutyrate (BHB) during HS on feed intake and metabolites. Under TN conditions the cows received a bolus dose of BHB and dry matter intake (DMI) and metabolites were measured. The second part of this study used a bolus of MAA to limit the up-stream production of acetyl-CoA available for ketogenesis by inhibiting ß-oxidation. We proposed that dosing lactating dairy cows with BHB would decrease DMI, increase plasma insulin, decrease NEFAs and increase skin temperature by vasodilatation. The same cows were then subjected to HS and dosed with saline and MAA on different test days. The infusion of BHB increased skin temperature (time 0.5, 1, 2, 3 and 4°C r² =0.98 with serum BHB) and decreased serum NEFA levels (P < 0.01). There was no change in mean DMI, glucose or insulin. The bolus of MAA decreased feed intake, vaginal temperature, and insulin. There was an increase in serum BHB with the initial dose of MAA and an initial decrease in serum glucose (P < 0.0001) with MAA. Serum glucose increased as insulin decreased with MAA. The infusion of BHB did not alter feed intake in this study despite high plasma levels of BHB.