BHBA Levels Research Articles

β-Hydroxybutyric acid inhibits growth hormone-releasing hormone synthesis and secretion through the GPR109A/extracellular signal-regulated 1/2 signalling pathway in the hypothalamus.

β-Hydroxybutyric acid (BHBA) has recently been shown to regulate hormone synthesis and secretion in the hypothalamus. However, little is known about the effects of BHBA-mediated hormone regulation or the detailed mechanisms by which BHBA regulates growth hormone-releasing hormone (GHRH) synthesis and secretion. In the present study, we examined the expression of the BHBA receptor GPR109A in primary hypothalamic cell cultures. We hypothesised that BHBA regulates GHRH via GPR109A and its downstream signals. Initial in vivo studies conducted in rats demonstrated that GHRH mRNA expression in the hypothalamus was strongly inversely correlated with BHBA levels in the cerebrospinal fluid during postnatal development (r = -0.89, P < 0.01). Furthermore, i.c.v. administration of BHBA acutely decreased GHRH mRNA expression in rats. Further in vitro studies revealed a decrease in GHRH synthesis and secretion in primary hypothalamic cells after treatment with BHBA; this effect was inhibited when hypothalamic cells were pretreated with pertussis toxin (PTX). BHBA had no effect on GHRH synthesis and secretion in GT1-7 cells, which do not exhibit cell surface expression of GPR109A. Furthermore, BHBA acutely decreased the transcription of the homeobox gene for Gsh-1 in the hypothalamus in both in vivo and in vitro, and this effect was also inhibited by PTX in vitro. In primary hypothalamic cells, BHBA activated the extracellular signal-regulated kinase (ERK)1/2, p38 and c-Jun N-terminal kinase mitogen-activated protein kinase (MAPK) kinases, as shown by western blot analysis. Moreover, inhibition of ERK1/2 with U0126 attenuated the BHBA-mediated reduction in Gsh-1 expression and GHRH synthesis and secretion. These results strongly suggest that BHBA directly regulates GHRH synthesis and secretion via the GPR109A/ERK1/2 MAPK pathway, and also that Gsh-1 is essential for this function.

Plasma parameters related to energy and lipid metabolism in periparturient Modenese and Italian Friesian cows.

The aim of this work was to compare energy and lipid metabolism during the peripartum period between Modenese (MO) and Italian Friesian (IF) cows. The study was carried out on 33 pluriparous pregnant cows, 19 IF and 14 MO, reared together in the same herd and kept under equal conditions of management and nutrition. Blood was sampled from jugular vein starting 4 week before expected calving date until 4 week post-calving, once weekly. Plasma was analysed for glucose, NEFA, BHBA, triglycerides and cholesterol concentrations. Body condition score (BCS) was assessed weekly after blood sampling. Data from antepartum (a.p.) and post-partum (p.p.) periods were separately analysed as repeated measures by a linear mixed models with the effect of breed, time and their interaction as main factors and random cow within breed. The energy status differed between the two breeds during the peripartum period. We observed higher BCS a.p. and p.p. and lower BCS variations p.p. in MO compared to IF group. Modenese cows showed lower glucose and cholesterol concentrations (p < 0.001), but higher NEFA values, NEFA to cholesterol and NEFA to albumin ratios (p < 0.001) during a.p.; on the contrary, IF cows had higher (p < 0.05) cholesterol, NEFA, BHBA levels and NEFA to albumin ratio than MO ones during p.p. The differences observed between the two breeds suggest how MO cows are subjected to lipid mobilization during late gestation; on the contrary, IF cows are predisposed to mobilize their lipid reserves at the beginning of lactation to support high production. The results indicate a diverse ability to cope with metabolic stress and suggest the hypothesis that the differences in concentrations of plasma parameters and their variation amplitude around the calving period might depend on the different genetic merit for milk production between the two breeds.

Association of digital cushion thickness with sole temperature measured with the use of infrared thermography

The main objective of this study was to investigate the association between digital cushion thickness and sole temperature measured by infrared thermography. Data were collected from 216 lactating Holstein cows at 4 to 10d in milk (DIM). Cows were locomotion scored and sole temperature was measured after claw trimming (a minimum delay of 3min was allowed for the hoof to cool) using an infrared thermography camera. Temperature was measured at the typical ulcer site of the lateral digit of the left hind foot. Immediately after the thermographic image was obtained, the thickness of the digital cushion was measured by ultrasonography. Rumen fluid samples were collected with a stomach tube and sample pH was measured immediately after collection. Additionally, a blood sample was obtained and used for measurements of serum concentrations of β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and haptoglobin. To evaluate the associations of digital cushion thickness with sole temperature, a linear regression model was built using the GLIMMIX procedure in SAS software (SAS Institute Inc., Cary, NC). Sole temperature was the response variable, and digital cushion thickness quartiles, locomotion score group, rumen fluid pH, rumen fluid sample volume, environmental temperature, age in days, and serum levels of NEFA, BHBA, and haptoglobin were fitted in the model. Only significant variables were retained in the final model. Simple linear regression scatter plots were used to illustrate associations between sole temperature (measured by infrared thermography at the typical ulcer site) and environmental temperature and between NEFA and BHBA serum levels and haptoglobin. One-way ANOVA was used to compare rumen fluid pH for different locomotion score groups and for different digital cushion quartiles. Results from the multivariable linear regression model showed that sole temperature increased as locomotion scores increased and decreased as digital cushion thickness increased. These results were adjusted for environmental temperature, which was significantly associated with sole temperature. Serum levels of NEFA, BHBA, and haptoglobin were not associated with sole temperature. However, significant correlations existed between serum levels of NEFA and haptoglobin and between serum levels of BHBA and haptoglobin. Rumen fluid pH was not associated with either locomotion score or digital cushion thickness. In conclusion, we show here that digital cushion thickness was associated with sole temperature in cows at 4 to 10 DIM.

Correlations between Milk and Plasma Levels of Amino and Carboxylic Acids in Dairy Cows

The objective of this study was to investigate the relationship between the concentrations of 19 amino acids, glucose, and seven carboxylic acids in the blood and milk of dairy cows and their correlations with established markers of ketosis. To that end, blood plasma and milk specimens were collected throughout lactation in two breeds of dairy cows of different milk yield. Plasma concentrations of glucose, pyruvate, lactate, α-aminobutyrate, β-hydroxybutyrate (BHBA), and most amino acids, except for glutamate and aspartate, were on average 9.9-fold higher than their respective milk levels. In contrast, glutamate, aspartate, and the Krebs cycle intermediates succinate, fumarate, malate, and citrate were on average 9.1-fold higher in milk than in plasma. For most metabolites, with the exception of BHBA and threonine, no significant correlations were observed between their levels in plasma and milk. Additionally, milk levels of acetone showed significant direct relationships with the glycine-to-alanine ratio and the BHBA concentration in plasma. The marked decline in plasma concentrations of glucose, pyruvate, lactate, and alanine in cows with plasma BHBA levels above the diagnostic cutoff point for subclinical ketosis suggests that these animals fail to meet their glucose demand and, as a consequence, rely increasingly on ketone bodies as a source of energy. The concomitant increase in plasma glycine may reflect not only the excessive depletion of protein reserves but also a potential deficiency of vitamin B6.

Prevalence of subclinical ketosis and relationships with postpartum diseases in European dairy cows

Subclinical ketosis (SCK) is defined as concentrations of β-hydroxybutyrate (BHBA) ≥1.2 to 1.4mmol/L and it is considered a gateway condition for other metabolic and infectious disorders such as metritis, mastitis, clinical ketosis, and displaced abomasum. Reported prevalence rates range from 6.9 to 43% in the first 2mo of lactation. However, there is a dearth of information on prevalence rates considering the diversity of European dairy farms. The objectives of this study were to (1) determine prevalence of SCK, (2) identify thresholds of BHBA, and (3) study their relationships with postpartum metritis, clinical ketosis, displaced abomasum, lameness, and mastitis in European dairy farms. From May to October 2011, a convenience sample of 528 dairy herds from Croatia, Germany, Hungary, Italy, Poland, Portugal, Serbia, Slovenia, Spain, and Turkey was studied. β-Hydroxybutyrate levels were measured in 5,884 cows with a handheld meter within 2 to 15 d in milk (DIM). On average, 11 cows were enrolled per farm and relevant information (e.g., DIM, postpartum diseases, herd size) was recorded. Using receiver operator characteristic curve analyses, blood BHBA thresholds were determined for the occurrence of metritis, mastitis, clinical ketosis, displaced abomasum, and lameness. Multivariate binary logistic regression models were built for each disease, considering cow as the experimental unit and herd as a random effect. Overall prevalence of SCK (i.e., blood BHBA ≥1.2mmol/L) within 10 countries was 21.8%, ranging from 11.2 to 36.6%. Cows with SCK had 1.5, 9.5, and 5.0 times greater odds of developing metritis, clinical ketosis, and displaced abomasum, respectively. Multivariate binary logistic regression models demonstrated that cows with blood BHBA levels of ≥1.4, ≥1.1 and ≥1.7mmol/L during 2 to 15 DIM had 1.7, 10.5, and 6.9 times greater odds of developing metritis, clinical ketosis, and displaced abomasum, respectively, compared with cows with lower BHBA blood levels. Interestingly, a postpartum blood BHBA threshold ≥1.1mmol/L increased the odds for lameness in dairy cows 1.8 (95% confidence interval: 1.3 to 2.5) times. Overall, prevalence of SCK was high between 2 to 15 DIM and SCK increased the odds of metritis, clinical ketosis, lameness, and displaced abomasum in European dairy herds.

Comparing the Urine Ketone Strip Test and the Handheld Ketone Meter to Diagnose Ketosis in Early Lactation Dairy Cows

Ketosis is a common metabolic disease in fresh dairy cows. Clinical and subclinical ketosis (SCK) can cause reduced milk yield, decreased milk protein, reduced reproductive capacity, and increased risk of displaced abomasum. Usually, diagnosing ketosis is performed by measuring acetoacetate or BHBA levels in the blood, urine, or milk samples. Measuring BHBA in serum or plasma is considered the gold standard diagnostic test for subclinical ketosis, because this method has stability, but the price for ketone strips is approximately $0.08/strip while the price for the electronic BHBA measuring system is approximately $1.00. UF/IFAS researchers conducted a study to compare the two, using 72 Holstein cows between 14–40 days in milk from three dairy farms in north-central Florida with 450–800 lactating dairy cows. The key finding for this experiment is that no difference exists in BHBA concentration between cows that had a trace or small in the ketone strip reading. This 3-page fact sheet was written by Klibs N. Galvão, Achilles Vieira Neto, Gustavo Peña, Joao Bittar, and Lucas Ibarbia, and published by the UF Department of Veterinary Medicine-Large Animal Clinical Sciences, October 2012. VM186/VM186: Comparing the Urine Ketone Strip Test and the Handheld Ketone Meter to Diagnose Ketosis in Early Lactation Dairy Cows (ufl.edu)

Fluctuations in energy-related metabolites during the peri-parturition period in Lori-Bakhtiari ewes

This study describes the fluctuations in serum energy-related metabolites during a period of 2 weeks before, to 2 weeks after parturition in Lori-Bakhtiari ewes. The effect of parity was also studied. Blood profiles were determined in 60 healthy pregnant ewes with single (n=30) and twin (n=30) lambings. Blood was collected from each ewe on days 14 and 7 prepartum, and days 7 and 14 postpartum to determine the serum non-esterified fatty acid (NEFA), β-hydroxybutyrate (BHBA), glucose, cholesterol, blood urea nitrogen (BUN) and calcium (Ca) levels. The age of the ewes had no significant effect on the energy metabolism indicators. Serum NEFA, BHBA, glucose, BUN and calcium concentrations recorded peak levels 7 days before parturition. However, NEFA and BHBA recorded significant changes (P<0.05) during the peri-parturition period. All metabolites changed significantly in ewes carrying twin-bearing ewes, compared to single-bearing ewes. Serum BHBA concentrations recorded positive correlations with the serum NEFA (P<0.01) and cholesterol (P<0.05), while blood glucose had negative correlations (P<0.01) with NEFA, BHBA and Ca. Blood NEFA and BHBA recorded positive correlations (P<0.05) with the BUN levels and negative correlations (P<0.05) with Ca. The results showed that blood NEFA and BHBA levels are sensitive indicators of the energy balance during the peri-parturition period in ewes.

Serum acute phase proteins in control and Theileria annulata infected water buffaloes (Bubalus bubalis)

This study was carried out to ascertain the changes in acute phase proteins (APPs) and pro-inflammatory cytokines in Theileria annulata infected water buffalo. Thirty infected water buffaloes and 20 parasitologically free were used. In the present study there was significant (P≤0.05) increase in haptoglobin (Hp), serum amyloid A (SAA), ceruloplasmin, α1-acid glycoprotein (AGP) and fibrinogen levels (2.18±0.29g/l, 156.58±3.48mg/l, 31.23±1.25mg/dl, 370.23±33.21mg/l and 16.17±1.18g/l, respectively) in T. annulata infected water buffaloes when compared to healthy ones (0.13±0.01g/l, 23.9±0.56mg/l, 21.23±1.21mg/dl, 240.53±22.45mg/l and 4.2±0.16g/l, respectively). Moreover, there was significant (P≤0.05) increase in the levels of TNF-α, IL-1α, IL-6, IL-12, IL-1β and IFN-γ (2.55±0.12ng/ml, 98.32±4.21pg/ml, 152.32±5.62pg/ml, 26.44±1.43ng/ml, 240.33±20.45pg/ml and 123.65±5.67pg/ml, respectively) in T. annulata infected water buffaloes when compared to healthy ones (0.42±0.04ng/ml, 55.32±3.21pg/ml, 88.23±3.21pg/ml, 7.45±0.67ng/ml, 98.33±3.45pg/ml and 34.76±1.56pg/ml, respectively). There was also significant decrease (P≤0.05) in the Hb content, PCV%, RBCs and WBCs counts in the diseased water buffaloes compared to the control ones. Neutropenia, eosinopenia, lymphopenia, monocytopenia and thrombocytopenia were also recorded. The biochemical changes revealed significant (P≤0.05) elevation in the levels of AST, ALT, ALP, LDL-c, VLDL-c, BHBA and NEFA, with significant (P≤0.05) decrease in the levels of total proteins, albumin, globulins, cholesterol, triglyceride, glucose, G6PD, calcium and phosphorus in T. annulata infected water buffaloes when compared to healthy ones. It could be concluded that APPs and pro-inflammatory cytokines could be used as a valuable biomarkers in T. annulata infected water buffaloes (Bubalus bubalis).

The association of serum metabolites in the transition period with milk production and early-lactation reproductive performance

The objective was to examine the associations of peripartum concentrations of nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and calcium with milk production in early lactation and pregnancy at the first artificial insemination (AI) across different management systems. Fifty-five Holstein freestall dairy herds located across the United States and Canada were visited weekly for blood sample collection from 2,365 cows. For each week of sampling (from wk −1 through wk 3 relative to calving) and for each metabolite, serum concentrations were dichotomized at various thresholds to identify the thresholds with the best negative associations with milk production and pregnancy at first AI. These thresholds were used to categorize the serum concentrations into higher and lower risk categories. Repeated-measures ANOVA and multivariable logistic regression were conducted for milk production and pregnancy at the first AI data, respectively, considering cow as the experimental unit and herd as a random effect. In the week before calving, serum NEFA ≥0.5mEq/L, BHBA ≥600μmol/L, and calcium ≤2.1mmol/L were associated with 1.6 to 3.2 kg/d milk loss across the first 4 Dairy Herd Improvement Association (DHIA) milk tests. High levels of NEFA and BHBA in wk 1 and 2 after calving (≥0.7 and ≥1.0mEq/L for NEFA, and ≥1,400 and ≥1,200μmol/L for BHBA), and low levels of calcium (≤2.1mmol/L) in wk 1, 2 and 3 after calving were associated with milk loss at the first DHIA milk test. Serum concentrations of NEFA and BHBA were not associated with pregnancy at first AI in any sampling week, whereas calcium <2.2 to 2.4mmol/L from wk 1 through wk 3 postpartum were associated with reduced pregnancy at first AI. In conclusion, high serum concentrations of NEFA, BHBA, and low concentrations of calcium around parturition were associated with early lactation milk loss, and low calcium concentration around parturition was associated with impaired early lactation reproduction.

Estimation of herd-basis energy status in clinically healthy Holstein cows: Practical implications of body condition scoring and shortened metabolic profiles

The objective of the study was to estimate herd-basis energy status (ES) using body condition scoring (BCS) and shortened metabolic profiles in multiparous clinically healthy dairy cows and to evaluate if such profiles can be informative in herd investigation to indicate on metabolic herd problems. A total of 180 Holstein cows from commercial herd were clinically examined and assigned to one of 3 equal groups: dry cows (15 days before expected calving), puerperal (10 days after calving) and cows at day 60 of lactation. Blood were sampled and analyzed for total protein, albumin, urea nitrogen (UN), β-hydroxybutyrate (BHBA), glucose and total bilirubin. Liver samples by percutaneous biopsies were obtained at puerperal period and tested for lipid content. The cows had a mean BCS of 3.92±0.03 at dry period, 3.08 ± 0.03 at puerperal period and 2.82 ± 0.02 at day 60 of lactation. Average total protein, albumin and glucose concentrations were within the physiological range, whereas UN was higher than physiologically accepted, at all examined periods. BHBA levels increased after calving and 61.66% of puerperal cows had BHBA levels above 1 mmol/L. Average total bilirubin concentration after calving was higher than recommended. Concentrations of UN, BHBA and total bilirubin were positively correlated, whereas concentrations of total protein and glucose were negatively correlated with fatty liver degree. Albumin concentration was not correlated with fatty liver degree. In conclusion, although clinically healthy the examined cows were not in adequate ES during the transition period. Consequently, 55% of the cows had moderate to severe fatty liver. A sufficient number of highly significant correlations suggest that employed metabolic profiles may offer an indirect means of estimation energy status on a herd basis. Key words: Cow, energy status, metabolic profile, body condition score.

Effects of turning to 100% organic feed on metabolic status of Swedish organic dairy cows

Since January 2008 the ration for organic herds has been required to be 100% organic (Regulation No. 889/2008). However, this may not satisfy the high energy demands of early lactation cows. We thus investigated the possible effects of 100% organic feed on the energy balance in Swedish organic dairy herds as indicated by the following blood parameters (n=739 observations): Beta-hydroxybutyrate (BHBA), non-esterified fatty acid (NEFA) and insulin, and the occurrence of clinical ketosis (n=8769 observations). Thirteen organic and 13 conventional herds were visited and blood samples from 81 cows around parturition (≥3 cows per herd) were used. The metabolic status of the same herds under the previous rules was available for comparison. The BHBA, NEFA and insulin levels were different before and after the change of legislation, but the effects were similar in organic and conventional cows. The incidence of clinical ketosis was not associated with herd type or the change of legislation. Thus the change in legislation did not appear to have had any detrimental effects on the metabolic profiles of organic cows in early lactation and there was no evidence that organic cows were metabolically more challenged or had a severe negative energy balance.

Effects of divergent Holstein-Friesian strain and diet on diurnal patterns of plasma metabolites and hormones

Commonly measured metabolite and hormone concentrations used to describe the metabolic status of lactating cows undergo diurnal variation resulting in distinct patterns. Studies have shown that feeding events can modulate these diurnal patterns as cows respond to the nutrient intake. What is less clear is the extent to which cow genetics and diet interact to modify the diurnal patterns of specific nutritionally related metabolites and hormones. The objective of this study was to investigate diurnal patterns in circulating metabolite and hormone concentrations in divergent strains of Holstein-Friesian cows (North American, NA; and New Zealand, NZ) offered either fresh pasture (FP) or a total mixed ration (TMR). Plasma concentrations of growth hormone (GH), insulin-like growth factor-1 (IGF-1), glucose, insulin, β-hydroxybutyrate (BHBA), and non-esterified fatty acids (NEFA) were determined at 4-h intervals for a minimum of three consecutive days. All of the above metabolites and hormones exhibited within-day variability. Main effects of genetic strain and diet were observed for plasma IGF-1, and a strain by diet interaction was observed for GH. Time of day x diet interactions were observed for both glucose and insulin. Three-way interactions (time of day x diet x strain) were observed for BHBA and NEFA. These data indicate different levels of diurnal variation, with glucose, insulin, NEFA and BHBA having the largest daily variation. These diurnal patterns need to be considered in future investigations of these metabolites and hormones.

Evaluation of the Change of Serum Copper and Zinc Concentrations of Dairy Cows with Subclinical Ketosis

Ketosis in dairy cows can lead to poor reproductive success and decreased milk production. Since the serum concentrations of copper (Cu) and zinc (Zn) are closely associated with the health status of cows, we investigated whether serum concentrations of Cu and Zn differed in dairy cows with subclinical ketosis and healthy dairy cows. Blood samples of 19 healthy dairy cows and 15 subclinically ketotic dairy cows were collected from three farms, and the concentrations of β-hydroxybutyrate (BHBA), glucose, non-esterified fatty acids (NEFA), Cu, and Zn were determined. Subclinically ketotic dairy cows had significantly higher BHBA and NEFA levels (p < 0.01) and lower glucose (p < 0.01) than healthy dairy cows. Likewise, serum concentrations of Zn were significantly decreased (p < 0.05) in dairy cows with subclinical ketosis. There was no significant difference observed for serum Cu concentration between healthy and subclinically ketotic dairy cows. This study suggests that a decreased serum Zn concentration could be a cause of decreased reproductive performance in subclinically ketotic dairy cows.

Impact of postpartum milking frequency on the immune system and the blood metabolite concentration of dairy cows

The transition from pregnancy to lactation is marked by metabolic, hormonal, and immunological changes that have an impact on the incidence of infectious and metabolic diseases. The aim of this study was to evaluate the effect on immune function and blood metabolite concentration of limiting milk production in early lactation to reduce negative energy balance. Twenty-two multiparous Holstein cows were milked either once a day (1×) or twice a day (2×) for the first week postpartum. All cows were milked twice daily for the rest of lactation. Blood concentrations of nonesterified fatty acids (NEFA), β-hydroxybutyric acid (BHBA), calcium, bilirubin, urea, phosphorus, glucose, leptin, stanniocalcin-1, and 17β-estradiol were determined in samples collected from 5 wk before scheduled calving to 5 wk after calving. Polymorphonuclear leukocytes (PMNL) were isolated from blood to conduct assays for chemotaxis, phagocytosis, and respiratory burst. Peripheral blood mononuclear cells (PBMC) were isolated to evaluate lymphocyte proliferation and cytokine production (tumor necrosis factor-α, IL-4, and interferon-γ). Cows milked 1× produced 31% less milk than cows milked 2× during the first week of lactation. Over the following 13 wk of lactation, the milk production of cows milked 1× during the first week was 8.1% lower than for cows milked 2×. However, because the percentages of fat and protein were greater in the milk from 1× cows, the yields of milk components and energy-corrected milk were similar. Calving induced an increase in the concentrations of NEFA, BHBA, urea, and bilirubin. The increases in levels of NEFA and BHBA were greater in cows milked 2× than in cows milked 1×. During the same period, the serum glucose concentration decreased but remained greater in cows milked 1×. Serum calcium on d 4 and serum phosphorus on d 4 and 5 were greater in cows milked 1×. The differences between the 2 groups persisted beyond treatment until postpartum d 24 for NEFA and glucose and until postpartum d 14 for BHBA. After calving, the concentrations of leptin and stanniocalcin-1 decreased. During the first week postpartum, the decrease of leptin was less marked in cows milked 1×. The immune functions of PBMC and PMNL isolated from experimental cows and incubated using a standard medium did not show clear-cut peripartum immunosuppression. These variables were not significantly affected by the treatments, with the exception of interferon-γ secretion, which was greater on d 5 and 14 in cows milked 1×. In conclusion, limiting milk production in early lactation had positive effects on metabolite concentration, but larger studies are necessary to establish if this could reduce disease incidence.

Metabolic adaptations associated with irreversible glucose loss are different to those observed during under-nutrition

In this study the hypothesis that irreversible glucose loss results in an ‘uncoupling’ of the somatotrophic axis (increasing plasma GH levels and decreasing plasma IGF-I) was tested. During periods of negative energy balance the somatotrophic axis respond by increasing plasma GH and decreasing plasma IGF-I levels. In turn, elevated GH repartitions nutrient by increasing lipolysis and protein synthesis, and decreases protein degradation. Irreversible glucose loss was induced using sub-cutaneous injections of phloridizin. Seven non-lactating cows were treated with 8 g/day phloridizin (PHZ) and seven control animals (CTRL, 0 g/day), while being restricted to a diet of 80% maintenance. PHZ treatment increased urinary glucose excretion ( P < 0.001), resulting in hypoglycemia ( P < 0.001). As a response to this glucose loss, the PHZ treated animals had elevated plasma NEFA ( P < 0.005) and BHBA ( P < 0.001) levels. Average plasma insulin concentrations were not altered with PHZ treatment ( P = 0.059). Plasma GH was not different between the two groups ( P > 0.1), whereas plasma IGF-I levels decreased significantly ( P < 0.001) with PHZ treatment. The decline in plasma IGF-I concentrations was mirrored by a decrease in the abundance of hepatic IGF-I mRNA ( P = 0.005), in addition the abundance of hepatic mRNA for both growth hormone receptors (GHR(tot) and GHR(1A)) was also decreased ( P < 0.05). Therefore, the irreversible glucose loss resulted in a partial ‘uncoupling’ of the somatotrophic axis, as no increase in plasma GH levels occurred although plasma IGF-I levels, hepatic IGF-I mRNA declined, and the abundance of liver GH receptor mRNA declined.

Effect of administration of live Saccharomyces cerevisiae on milk production, milk composition, blood metabolites, and faecal flora in early lactating dairy goats

The effects of live Saccharomyces cerevisiae (CNCM I-1077) supplementation to 72 Saanen dairy goats in early lactation were investigated. Animals were divided into treatment and control groups balanced for parity and milk production in the first 3 weeks of lactation. Treated animals received 0.2 g/day yeast supplement (Levucell SC20) corresponding to 4 × 10 9 cfu/day S. cerevisiae, beginning week 3 of lactation, and lasting 15 weeks. Dry matter intake (DMI), body condition score (BCS), milk production and composition were recorded to day126 postpartum. Milk samples were analysed weekly for fat, protein, lactose, urea and SCC. Blood samples were analysed monthly for glucose, BHBA, NEFA, GOT and GGT. Intestinal microflora were assessed monthly in faeces, assaying total bacteria, enterobacteria, E. coli, coliform bacteria, clostridia, lactobacilli, molds and yeast. BCS was not affected by the treatment, but treated animals had greater DMI (2.71 kg/day versus 2.35 kg/day, S.E. ±0.12, P < 0.001) and produced more ( P < 0.05) milk (2.38 kg/day versus 2.08 kg/day, S.E. ±0.14) of lower fat content ( P < 0.05). Plasma metabolites and liver enzymes (GOT, GGT) were similar between groups, although BHBA levels tended to be lower ( P = 0.06) in treated animals. Faecal E. coli were reduced (0.72 log 10 cfu/g versus 2.39 log 10 cfu/g, S.E. ±0.38, P < 0.05) and lactobacilli increased ( P < 0.05) by the treatment. Yeast faecal levels were higher ( P < 0.001) in treated animals during supplementation. In this study, live yeast supplementation to early lactating dairy goats significantly increased milk production, in relation to increased DMI, without decreasing BCS. Plasma metabolites (glucose, BHBA and NEFA) were consistent with the BCS findings (no differences between groups) and in addition there was a significant reduction of faecal E. coli content together with increase in lactobacilli in the treated animals, suggesting greater stability of the intestinal ecosystem. Results suggest that the inclusion of Saccharomyces cerevisae in the diet of early lactating dairy goats can be recommended under field conditions.

Comparative Plasma and Urine Chemistry of Fasting White-Tailed Prairie Dogs (Cynomys leucurus) and American Martens (Martes americana): Representative Fat- and Lean-Bodied Animals

American martens and white-tailed prairie dogs are mammals of similar body mass, exposed to periods of food deprivation, but of vastly different body fat content. While both species demonstrated a protein conservation phase during a short-term fast, martens had a greater reliance on protein as depicted by greater loss of body weight, higher daily urine volume, and glomerular clearance rates, as well as higher daily urinary urea excretion. Protein use was calculated to be 3.15 and 1.23 g/d for martens and prairie dogs, respectively. Martens did not hydrolyze a greater amount of urea as they were hypothesized to do in order to conserve water. Urinary beta-hydroxybutyrate (BHBA) excretion decreased during the fast in both species but prairie dogs had higher plasma levels of BHBA, which suggests that regulation of protein catabolism may be in part from ketone bodies. By using fat and protein in a ratio of about 2:1, martens may maintain suficient hydration, extend their fat stores, and retain muscle integrity during short-term fasts.