Indicator Of Energy Status Research Articles

Influence of Energy Balance on Reproductive Performance and Milk Production of Dairy Cows at Pre-partum and Early Lactation Periods

The objective of this study was to evaluate the influence of energy balance in dairy cows at pre-partum and early lactation periods on their subsequent reproductive and productive performance. High producing, Ayrshire cows were randomly selected from the heavy pregnant, dry cow herd of Ambewela dairy farm in Up-Country, Sri Lanka. The serum NEFA (non esterifie fatty acid) and milk BHBA (beta hydroxyl butyric acid) concentrations were used as indicators of energy status of the cows. Days for the first AI, open days and conception rate were used to evaluate the reproductive performance. Sub-clinical ketosis (milk BHBA≥200 μmol/L BHBA level in milk during the lactation period from 10 to 60 days took longest period for the first AI and had the highest open days. Only 36% cows were pregnant at 100 days post-partum. Further, none of the cows showed sub-clinical ketosis during 100 days post-partum was pregnant. They had higher circulating NEFA levels at 5 days pre-partum and 10 days post-partum periods and significantly lower (p<0.05) in milk production compared to their pregnant counterparts. This study indicated that the magnitude and duration of the prepartum energy status (i.e., negative energy balance) has a detrimental effect on subsequent reproductive and productive performances in high producing dairy cows.

Does β-hydroxybutyrate concentration influence conception date in young postpartum range beef cows?1

Cows in negative energy balance after calving often have reduced reproductive performance, which is mediated by metabolic signals. The objective of these studies was to determine the association of serum metabolites, days to first postpartum ovulation, milk production, cow BW change, BCS, and calf performance with conception date in spring-calving 2- and 3-yr-old beef cows grazing native range. In Exp. 1, cows were classified by conception date in a 60-d breeding season as early (EARLY; conceived in first 15 d of breeding) or late conception (LATE; conceived during the last 45 d of breeding). Beginning on d 35 postpartum, blood samples were collected twice per week for serum metabolite analysis and progesterone analysis to estimate days to resumption of estrous cycles. As a chute-side measure of nutrient status and glucose sufficiency, whole-blood β-hydroxybutyrate (BHB) concentrations were measured 14 ± 2 d before breeding. In Exp. 2, cows were classified by subsequent calving date resulting from a 55 ± 2 d breeding season as conceiving either early (EARLY; conceived in first 15 d of breeding) or late (LATE; conceived during the remaining breeding season). Blood samples were collected in 2 periods, 30 ± 4 d before calving and 14 ± 3 d before the initiation of breeding, to determine circulating concentrations of IGF-I and BHB. In Exp. 1, BHB and serum glucose concentrations were less (P ≤ 0.04) in EARLY cows than LATE cows. Serum insulin concentrations were greater (P = 0.03) in EARLY cows relative to LATE cows. Milk production and composition did not differ (P ≥ 0.24) by conception date groups. In Exp. 2, cow age × sample period × conception date interaction (P < 0.01) occurred for serum BHB concentrations. Serum BHB concentrations were similar (P > 0.10) for 2-yr-old cows (in greater nutritional plane compared with Exp. 1) regardless of their conception date classification and sampling period. However, precalving serum BHB concentrations were greater (P < 0.01) for LATE than EARLY in 3-yr-old cows with no difference (P = 0.86) at prebreeding. Serum IGF-1 concentrations were greater (P < 0.01) for EARLY cows relative to LATE cows at precalving and prebreeding. This study indicates that blood BHB concentrations during times of metabolic dysfunctions may provide a more sensitive indicator of energy status than body condition, predicting rebreeding competence in young beef cows as measured by interval from calving to conception.

Association between energy status early postpartum and subsequent embryonic mortality in high-yielding recipient cows

High-yielding Holstein-Friesian recipients (n = 43) were used in order to investigate the relation between energy balance status during the early postpartum period and subsequent embryonic mortality after transferring good-quality frozen embryos. Blood samples were collected during the second, third, fourth, fifth, sixth and seventh weeks postpartum in order to measure energy status indicators. These indicators include β hydroxyl butyric acid (BHBA), non-esterified fatty acid (NEFA), total cholesterol (T-chol), glucose and blood urea nitrogen (BUN). Moreover, body condition scores (BCS) were assessed during the same period. Pregnancy diagnosis by ultrasonography at the 28th day postestrus and embryo viability was ascertained until 45 days postestrus in order to detect late embryonic mortality (LEM). The pregnancy rate on day 28 was 44.2% (19/43); however, five cows (11.6%) experienced LEM by day 45. Based on the non-return rate at day 24, non-pregnant animals, as diagnosed by ultrasonography, were allocated into animals with longer estrus intervals than 24 days (32.5%; mid-embryonic mortality (MEM) group) and animals returning to estrus by day 24 postestrus (23.5%; early embryonic mortality (EEM) group). At week 5 postpartum, BCS was significantly (P < 0.05) lower in the LEM group than that of pregnant (PREG), EEM and MEM groups. NEFA was significantly higher in animals that experienced LEM (LEM group) at week 7 postpartum (289.6 ± 47.0 µEq/L; P < 0.01) than that of PREG (196.8 ± 16.0 µEq/L), EEM (157.2 ± 18.6 µEq/L) and MEM groups (191.5 ± 14.4 µEq/L). In conclusion, lower BCS at week 5 postpartum and higher NEFAs at week 7 postpartum may be associated with subsequent LEM in high-yielding recipient cows.

Effect of parity and stage of lactation on feed sorting behavior of lactating dairy cows

The objectives of this study were to determine if feed sorting differs between primiparous (PP) and multiparous (MP) cows, if sorting changes from the period of peak lactation to peak dry matter intake (DMI), and whether feed sorting affects efficiency of production. Data on DMI, milk production, feed sorting (particle size of offered and refused feed), and energy status (plasma nonesterified fatty acid, β-hydroxybutyrate, insulin and glucose concentration) were collected on 30 PP and 30 MP lactating Holstein dairy cows, individually housed and fed in tie-stalls, during 3 wk (wk 2, 6, and 10) over 10 wk of a lactation study. Cows averaged 53, 81, and 109±10 d in milk (DIM) at the beginning of each of the 3 recording weeks. To determine sorting, feed samples were separated with a particle separator that had 3 screens (19, 8, and 1.18mm) and a bottom pan, resulting in 4 fractions (long, medium, short, fine). Over the study period, MP cows consumed more DM and produced more milk than did the PP cows, but had similar efficiency of production (kg of milk/kg of DMI), and similar levels of plasma indicators of energy status. Across the study period, DMI increased, whereas milk yield decreased, resulting in decreased efficiency of milk production as cows moved further into lactation. All cows had higher nonesterified fatty acid and lower insulin concentrations in plasma at 53 DIM compared with at 81 and 109 DIM, suggesting they were mobilizing more body fat at that earlier stage of lactation. Across periods, all cows sorted against the longest ration particles, did not sort the medium ration particles, and sorted for fine ration particles; as a result, all cows consumed less neutral detergent fiber (NDF) and physically effective NDF (proportion of NDF retained on the 19- and 8-mm screens of the particle separator) than predicted. Greater selection against the longest ration particles was associated with greater efficiency of milk production; however, this sorting pattern also tended to be associated with lower milk fat percentage. The extent of the observed sorting against the longest, physically effective ration particles and for the finest ration particles was greater for PP cows than for MP cows across all 3 observation periods. Feed sorting remained consistent in cows across the DIM evaluated in this study and that this sorting behavior can affect the efficiency of milk production as well as milk fat percentage. Further, PP cows engage in more sorting of their ration than MP cows.

Contrasts In Energy Status and Marine Foraging Strategies of White-Winged Scoters (Melanitta FUSCA) and Surf Scoters (M. Perspicillata)

ABSTRACT. White-winged Scoters (Melanitta fusca) and Surf Scoters (M. perspicillata) are often assumed to rely on similar marine resources. To evaluate the accuracy of this assumption, we contrast seasonal distributions, foraging effort, and indicators of energy status (body mass and composition, plasma metabolites) in three major foraging sites in Puget Sound, Washington, for these rapidly declining sea duck congeners. For Surf Scoters, distributions and energy status indicated that a mussel-dominated site was relatively important in early winter, but that importance shifted during late winter and spring to seagrass sites that provided either herring spawn or epifaunal invertebrates. As winter progressed, movements among foraging sites and increased foraging effort by Surf Scoters were accompanied by greater variability in their energy status compared with White-winged Scoters; body mass declined over winter by >9% in about one-third of past studies for Surf Scoters, well above the range of losses observ...

Relationships between endometritis and metabolic state during the transition period in pasture-grazed dairy cows

The primary objective of this study was to identify relationships between endometritis and metabolic state during the calving transition and early lactation periods. A subset of mixed age and breed dairy cows (n=78) from a seasonal, pasture-grazed herd of 389 cows was examined. The selected cows were grouped as having endometritis at d 42 postpartum or being unaffected by endometritis. Endometritis was defined as >6% (upper quartile) of uterine nucleated cells being polymorphonuclear cells (H-PMN; n=38); unaffected by endometritis was defined as ≤1% of nucleated cells being polymorphonuclear (L-PMN; n=40). Milk yield was determined at each milking, and milk composition (fat and protein) was determined at 2-wk intervals. Blood samples collected on d −14, 0 (d of calving), 4, 7, 14, 28, and 42 were analyzed for indicators of energy status (nonesterified fatty acids, glucose, and urea), liver function (albumin, globulin, glutamate dehydrogenase, and aspartate aminotransferase), inflammation (haptoglobin), and mineral status (Ca and Mg). Samples collected weekly from d 21 to 63 or 70 were analyzed for progesterone content. The postpartum anovulatory interval was defined to end on the first day postpartum that plasma progesterone concentration was ≥1 ng/mL. A greater percentage of H-PMN cows failed to ovulate before d 63 or 70 (34%) compared with L-PMN cows (10%), although the proportions of cows ovulating within either polymorphonuclear group was similar through d 56 postpartum. Plasma concentrations of albumin and the albumin:globulin ratio were consistently lower in H-PMN cows. Plasma Mg was lower, whereas glutamate dehydrogenase and aspartate aminotransferase were higher, in H-PMN cows during early lactation compared with L-PMN cows. Circulating metabolites indicative of energy status (nonesterified fatty acids, glucose, and urea) were not different between polymorphonuclear groups. Among 3- to 5-yr-old cows, daily milk yield for the first 42 d after calving was lower for H-PMN cows than for L-PMN cows. Among cows >5 yr old, protein percentage was lower in H-PMN cows compared with L-PMN cows. In summary, endometritis at 42 d postpartum in the herd studied was associated with an increased likelihood of remaining anovulatory. These cows had lower albumin concentrations throughout the calving transition period, perhaps indicating impaired liver function, with lower plasma Mg and evidence of hepatocellular damage in early lactation. Similar profiles of nonesterified fatty acids and glucose indicated that energy status was not a risk factor for endometritis.

The effect of body condition score at calving and supplementation with Saccharomyces cerevisiae on milk production, metabolic status, and rumen fermentation of dairy cows in early lactation

The objective of this study was to examine the effects of live yeast (LY) supplementation and body condition score (BCS, 1–5 scale) at calving on milk production, metabolic status, and rumen physiology of postpartum (PP) dairy cows. Forty Holstein-Friesian dairy cows were randomly allocated to a 2 × 2 factorial design and blocked by yield, parity, BCS, and predicted calving date. Treatments were body condition at calving (low for BCS ≤3.5 or high for BCS ≥3.75; n=20) and supplementation with LY (2.5 and 10g of LY/d per cow for pre- and postcalving, respectively; control, no LY supplementation; n=20). The supplement contained 109 cfu of Saccharomyces cerevisiae/g (Yea-Sacc1026 TS, Alltech Inc., Nashville, TN). Daily milk yield, dry matter intake, milk composition, BCS, body weight, and backfat thickness were recorded. Blood samples were harvested for metabolite analysis on d 1, 5, 15, 25, and 35 PP. Liver samples were harvested by biopsy for triacylglycerol (TAG) and glycogen analysis on d 7 precalving, and on d 7 and 21 PP. Rumen fluid was sampled by rumenocentesis for all cows on d 7 and 21 PP. Supplementation with LY had no effect on milk yield, dry matter intake, rumen fluid pH, or blood metabolites concentration of dairy cows with high or low BCS at calving. Feeding LY increased rumen acetate proportion and protozoal population, tended to increase liver glycogen, and decreased rumen ammonia nitrogen during early lactation. Over-conditioned cows at calving had greater body reserve mobilization and milk production and lower feed intake, whereas cows with a moderate BCS at calving had greater feed intake, lower concentrations of nonesterified fatty acids and β-hydroxybutyrate, lower liver TAG and TAG:glycogen ratio, and faster recovery from body condition loss. Additionally, the data suggest that concentrations of liver enzymes in blood might be used as an indicator for liver TAG:glycogen ratio. Results indicate that in the case of this experiment, where the control treatment was associated with an acceptable rumen pH, feeding yeast did not significantly improve indicators of energy status in dairy cows.

Body condition and indicators of energy status of cows in advanced gravidity and early stage of lactation

The objective of the investigations was to establish the validity of certain metabolic and endocrine indicators of energy metabolism in comparison with the body condition of cows during the final stage of pregnancy and the early stage of lactation. For the investigations, three groups of eight cows each were chosen during the dry period (15 days before the expected date of calving), in early puerperium (15 days after calving) and on the 100th day of lactation. All the animals included in the experiment were primipara or at their second delivery. The body condition of the cows in advanced pregnancy and lactation was evaluated according to the Elanco Animal Health Bulletin AI 8478 system. Concentrations of glucose and beta-hydroxybutyric acid (BHB) were determined in samples of fresh blood, and concentrations of total bilirubin, urea, triiodothyronine and thyroxine in samples of blood serum. The blood samples were taken during the dry period, in early puerperium, and on the 100th day of lactation. On the grounds of the obtained results, a high degree of correlation was determined between the body condition of cows in early puerperium and BHB concentrations in blood established 15 days prior to calving (r = 0.898; p &lt; 0.01). Contrary to this, a significant correlation was established between the body condition of cows in the dry period and the concentration of total bilirubin in cow blood 15 days after calving (r = 0.603; p &lt; 0.05). Furthermore, a high degree of correlation was established between the difference in the body condition of cows in the dry period and in early puerperium (X = 0.49 ? 0.21 pints) and BHB concentration in the blood of cows prior to calving (r = 0.800; p &lt; 0.02). It can be concluded on the grounds of the obtained results that changes in the body condition of cows that occur in the peripartal period are in significant correlation with BHB concentration in the blood of cows in the dry period and the concentration of total bilirubin in early puerperium. .

Regulation of food intake and energy expenditure by hypothalamic malonyl-CoA

Energy balance is monitored by the hypothalamus. Malonyl-CoA, an intermediate in fatty acid synthesis, serves as an indicator of energy status in the hypothalamic neurons. The cellular malonyl-CoA level is determined by its rate of synthesis, catalyzed by acetyl-CoA carboxylase (ACC), and rate of removal, by fatty acid synthase (FAS). Malonyl-CoA functions in the hypothalamic neurons that express orexigenic and anorexigenic neuropeptides. Inhibitors of FAS, administered systemically or intracerebroventricularly to mice, increase hypothalamic malony-CoA and suppress food intake. Recent evidence suggests that the changes of hypothalamic malonyl-CoA during feeding and fasting cycles are caused by changes in the phosphorylation state and activity of ACC mediated via 5'-AMP-activated protein kinase (AMPK). Stereotactic delivery of a viral malonyl-CoA decarboxylase (MCD) vector into the ventral hypothalamus lowers malonyl-CoA and increases food intake. Fasting decreases hypothalamic malonyl-CoA and refeeding increases hypothalamic malonyl-CoA, to alter feeding behavior in the predicted manner. Malonyl-CoA level is under the control of AMP kinase which phosphorylates/inactivates ACC. Malonyl-CoA is an inhibitor of carnitine palmitoyl-CoA transferase-1 (CPT1), an outer mitochondrial membrane enzyme that regulates entry into, and oxidation of fatty acids, by mitochondria. CPT1c, a recently discovered, brain-specific enzyme expressed in the hypothalamus, has high sequence similarity to liver/muscle CPT1a/b and binds malonyl-CoA, but does not catalyze the prototypical reaction. This suggests that CPT1c has a unique function or activation mechanism. CPT1c knockout (KO) mice have lower food intake, weigh less and have less body fat, consistent with the role as an energy-sensing malonyl-CoA target. Paradoxically, CPT1c protects against the effects of a high-fat diet. CPT1cKO mice exhibit decreased rates of fatty acid oxidation, consistent with their increased susceptibility to diet-induced obesity. We suggest that CPT1c may be a downstream target of malonyl-CoA that regulates energy homeostasis.

Strategies to improve fertility of high yielding dairy farms: Management of the dry period

Reproductive performance of dairy cattle has been related to a wide variety of indicators of energy status, e.g., extent of negative energy balance, time of energy balance nadir, body weight loss, body condition score, and body condition score loss. Energy balance begins to decrease during the last few weeks prior to calving primarily due to a 30–35% reduction in feed intake. Cows typically remain in negative energy balance for five to seven weeks postpartum. Nutritional strategies to improve energy balance during the transition period include fat supplementation and feeding additional nonfiber carbohydrate. Unfortunately, neither approach is likely to markedly enhance energy status, although fat supplementation may increase reproductive efficiency independent of any effect on energy balance. Alternative management strategies may be required to improve fertility of dairy cows. Shortening or eliminating the dry period may improve energy status of dairy cows and increase reproductive efficiency. Shortening or eliminating the dry period may enhance dry matter intake during the transition period, decrease milk energy output, or both. A preliminary study using small animal numbers indicated that reducing dry period length to 28 or 0 days may decreases days to first ovulation, increase first service conception rate, and decrease days open. A follow-up study employing large animal numbers confirmed that reducing dry period length from 55 to 34 days can decrease days to first ovulation and decrease the percentage of anovular cows. The reduction in days open was greater for older cows than second parity cows. The reduction in days open was not related to effects of treatment on milk yield. Shortening or eliminating the dry period may be a more successful approach to improving reproductive efficiency than diet manipulation.

Milk production responses to pre- and postcalving dry matter intake in grazing dairy cows

Sixty-eight multiparous grazing dairy cows were randomly allocated to two precalving pasture allowances to achieve differential dry matter intakes (DMI) for 29 ± 7.7 d precalving (Low or High DMI; 4.8 or 11.9 kg DM). At calving, cows within each precalving treatment were randomly allocated to one of two levels of feeding (Low or High DMI; 8.6 or 13.5 kg DM) for 35 d postcalving in a completely randomized design and a 2 × 2 factorial arrangement of treatments. Following treatments all cows grazed together and were fed pasture and pasture silage. Daily milk yields were recorded, and fat, protein and lactose concentrations determined weekly for 15 weeks. Blood was sampled weekly pre- and postcalving and analysed for indicators of energy status, growth hormone (GH) and insulin-like growth factor-1 (IGF-1). Body condition score (BCS) at calving was reduced by precalving restriction (P < 0.001; 2.8 and 3.0 for precalving Low and High treatment groups, respectively). Precalving restriction reduced milk fat production by 8.4% during the first 5 weeks postcalving, but differences were not significant subsequently. Postcalving feed restriction reduced yield of fat corrected milk (FCM), fat and protein by 23, 21 and 28%, respectively, during the first 5 weeks postcalving. Decreased (P < 0.05) yields of FCM, fat and protein (11, 10 and 9%, respectively) were also evident for 10 weeks after the feed restriction finished. There was a tendency (P < 0.1) for a precalving × postcalving DMI interaction in milk protein yield during the first 5 weeks of lactation with no effect of precalving level of feeding in cows that were restricted postcalving. The plasma concentrations of non-esterified fatty acids (NEFA), β-hydroxybutyrate (BOH) and GH were elevated in restricted cows precalving, and IGF-1 concentration was reduced. Plasma NEFA and BOH concentrations were elevated postcalving in restricted cows, but no effect of postcalving DMI on GH or IGF-1 concentration was evident. Results suggest that under grazing systems milk production responses to precalving DMI are small, but energy restrictions in early lactations result in significant carryover effects in milk production.

The Role of Hypothalamic Malonyl-CoA in Energy Homeostasis

Energy balance is monitored by hypothalamic neurons that respond to peripheral hormonal and afferent neural signals that sense energy status. Recent physiologic, pharmacologic, and genetic evidence has implicated malonyl-CoA, an intermediate in fatty acid synthesis, as a regulatory component of this energy-sensing system. The level of malonyl-CoA in the hypothalamus is dynamically regulated by fasting and feeding, which alter subsequent feeding behavior. Fatty acid synthase (FAS) inhibitors, administered systemically or intracerebroventricularly to lean or obese mice, increase hypothalamic malonyl-CoA leading to the suppression of food intake. Conversely, lowering malonyl-CoA with an acetyl-CoA carboxylase (ACC) inhibitor or by the ectopic expression of malonyl-CoA decarboxylase in the hypothalamus increases food intake and reverses inhibition by FAS inhibitors. Physiologically, the level of hypothalamic malonyl-CoA appears to be determined through phosphorylation/dephosphorylation of ACC by AMP kinase in response to changes in the AMP/ATP ratio, an indicator of energy status. Recent evidence suggests that the brain-specific carnitine:palmitoyl-CoA transferase-1 (CPT1c) may be a regulated target of malonyl-CoA that relays the "malonyl-CoA signal" in hypothalamic neurons that express the orexigenic and anorexigenic neuropeptides that regulate food intake and peripheral energy expenditure. Together these findings support a role for malonyl-CoA as an intermediary in the control of energy homeostasis.

Relationship between fat accumulation in the liver and energy intake, milk fat yield and blood metabolites in dairy cows

ABSTRACTIn the present study, 42 multiparous Holstein cows were used to investigate the relationship between fat accumulation in the liver and dry matter intake, milk yield and blood metabolites. Based on the percentage of fat in the liver cell at 2 weeks post‐parturition, the cows were classified into three groups. These groups were: (i) less than 10% of fat (normal group, n = 29); (ii) 10–20% of fat (mild group, n = 6); and (iii) more than 20% of fat (moderate group, n = 7). The bodyweight of the moderate group was high (771 kg) before calving. The sufficiency rates of total digestible nutrients (TDN) were remarkably decreased (approximately 65%) in early lactation. The milk fat yield and milk fat composition of the moderate group were higher (P &lt; 0.05) than the other groups at 1 and 2 weeks post‐parturition. It was suggested that non‐esterified fatty acids (NEFA) mobilized from adipose tissues was directly used by the mammary gland for synthesis of milk fat. The percentage of bromsulfalein (BSP) retention of the moderate group was high (21.1%) at 30 min, and it showed that the BSP clearance function was significantly decreased. The concentrations of NEFA, β‐hydroxybutyric acid and glucose were appropriate indicators of energy status; however, aspartate aminotransferase, γ‐glutamyl transpeptidase and total bilirubin were not sensitive indicators of a moderate fatty liver. Thus, high‐yielding cows that calve in an overweight condition are more likely to develop excessive fat accumulation in the liver because of great mobilization from adipose tissues post‐parturition. In cows with a moderately fatty liver, a decrease in TDN sufficiency rates, an increase of milk fat yield and a reduction of liver function were observed in early lactation. The increase of serum NEFA and milk fat composition resulting from mobilization of adipose tissues helped to diagnose moderate fatty liver.

Preoperative feeding preserves heart function and decreases oxidative injury in rats

Objective The nutritional status of a patient has been implicated as an important factor in the development of postoperative complications. Fasting before an operation may have detrimental effects on the metabolic state. We hypothesized that there was a positive correlation between preoperative nutritional status and postoperative organ function. Methods Preoperative feeding was compared with fasting with respect to effects on organ function and biochemical parameters in an animal model of extensive large abdominal surgery. Male Wistar rats were fed ad libitum or fasted for 16 h, after which the arteria mesenterica superior was clamped for 60 min followed by 180 min of reperfusion. Results After the ischemic period, heart function was significantly better in animals that were fed ad libitum than in fasted animals. Moreover, after intestinal ischemia and reperfusion, fed rats showed significantly higher levels of intestinal adenosine triphosphate and a significantly higher malondialdehyde concentration in the intestine and lung than did fasted rats. The ratio of adenosine triphosphate to adenosine diphosphate in the liver, an indicator of energy status, in fed rats was similar to that in a sham group, whereas fasted animals showed a significantly lower value. Conclusions Preoperative nutrition in contrast to fasting may attenuate ischemia/reperfusion-induced injury and preserve organ function in the rat.

Fasting Ghrelin Levels in Physically Active Women

1915 Ghrelin is a peripheral metabolic signal of energy status involved with the regulation of hunger, food intake, body weight, and energy balance. While recent evidence supports a potential physiological role of ghrelin in reproductive function, the relationship of ghrelin to exercise-associated menstrual disturbances and other endocrine adaptations to low energy availability has not been evaluated. PURPOSE: To test whether differences in fasting ghrelin levels exist in exercising women exhibiting alterations in metabolic status and menstrual cycle abnormalities. METHODS: Menstrual cycle status, defined as ovulatory, luteal phase deficient (LPD), anovulatory, or amenorrheic, was determined through daily urine collections examining estrone conjugates (E1C), pregnanediol-3-glucuronide (PdG), and luteinizing hormone (LH) for two to three consecutive cycles or equivalent time periods in 10 sedentary and 30 moderately active women. Both groups were matched for age (27.7 1.2 yrs), body mass (60.2 3.3 kg), menstrual cycle length (28.4 0.9 days), and reproductive age (14.4 1.2 yrs). A blood sample was collected once during the follicular phase of each menstrual cycle or on an arbitrary day in amenorrheic subjects and analyzed for total ghrelin, insulin, total T3, and leptin concentrations. Each subject was classified according to individual exercise status and the predominant menstrual cycle status displayed in at least two of the three, or two of the two, menstrual cycles evaluated. This classification resulted in 10 sedentary ovulatory subjects (SedOvul), 11 exercise ovulatory subjects (ExOvul), 11 exercise LPD or anovulatory subjects (ExLPD/ANOV), and 8 exercise amenorrheic (ExAmen) subjects. RESULTS: Ghrelin was significantly elevated in the ExAmen category (723.7 ± 40.8 pmol/L) when compared to all other categories (p<0.001), SedOvul (392.8 ± 32.0 pmol/L), ExOvul (418.0 ± 34.6 pmol/L), and ExLPD/Anov (380.4 ± 31.4 pmol/L). Leptin levels were lower in all groups versus SedOvul (P <0.001), while insulin was lower in both ExLPD/Anov and ExAmen categories versus SedOvul and ExOvul (p<0.018). Total T3 was lower in ExAmen compared to all other groups (P<0.001) with concentrations in ExLPD/Anov and ExOvul exceeding those in SedOvul (p<0.05). CONCLUSION: These data indicate a metabolic hormonal profile consistent with low energy availability in exercising women across a range of menstrual abnormalities. This study also introduces ghrelin as a potential additional indicator of energy status that uniquely discriminates amenorrheic athletes from athletes with other more subtle menstrual disturbances.

Hypothalamic malonyl-CoA as a mediator of feeding behavior.

Previous studies showed that i.p. administration of C75, a potent inhibitor of fatty acid synthase (FAS), blocked fasting-induced up-regulation of orexigenic neuropeptides and down-regulation of anorexigenic neuropeptides in the hypothalami of mice. As a result, food intake and body weight were drastically reduced. Here we provide evidence supporting the hypothesis that hypothalamic malonyl-CoA, a substrate of FAS, is an indicator of global energy status and mediates the feeding behavior of mice. We use a sensitive recycling assay to quantify malonyl-CoA to show that the hypothalamic malonyl-CoA level is low in fasted mice and rapidly (< or = 2 h) increases (approximately 5-fold) on refeeding. Intracerebroventricular (i.c.v.) administration of C75 to fasted mice rapidly (< or = 2 h) increased (by 4-fold) hypothalamic malonyl-CoA and blocked feeding when the mice were presented with food. Moreover, prior i.c.v. administration of an acetyl-CoA carboxylase inhibitor, 5-(tetradecyloxy)-2-furoic acid, rapidly (although only partially) prevented the C75-induced rise of hypothalamic malonyl-CoA and prevented the C75-induced decrease of food intake. These effects correlated closely with the rapid (< or = 2 h) and reciprocal effects of i.c.v. C75 on the expression of hypothalamic orexigenic (NPY and AgRP) and anorexigenic (proopiomelanocortin) neuropeptide mRNAs. Previous results showing that C75 administered i.c.v. rapidly activates hypothalamic neurons of the arcuate and paraventricular nuclei are consistent with the results reported in this paper. Together these findings suggest that level of hypothalamic malonyl-CoA, which depends on the relative activities of acetyl-CoA carboxylase and FAS, is an indicator of energy status and mediates feeding behavior.

Induction of heat shock protein 72 mRNA in skeletal muscle by exercise and training.

In response to stress, cells synthesise heat shock proteins (HSP) to maintain protein homeostasis. To study whether exercise and training induce expression of HSP72 in the middle gluteal muscle, 10 Finnhorses performed a submaximal 60 min exercise test on a treadmill. Test A was performed after 3 months of training, and the other two tests 2 (B) and 5 (C) weeks later. Blood samples were taken during and after the tests, and biopsy samples before, immediately after and 23 h after each test. HSP72 mRNA was analysed using a digoxigenin-labelled probe. Blood lactate concentration in the 3 tests varied between 7.2 and 10.2 mmol/l. Training increased HSP72 mRNA, as indicated by increases in samples taken at rest (A<B<C). Exercise also tended to increase HSP72 mRNA transiently but, 23 h later, values had returned to pre-exercise levels. HSP72 mRNA was expressed in all muscle fibres. After exercise, HSP72 mRNA correlated positively with the peak concentration of blood lactate, but not with indicators of energy status. Therefore, acidosis rather than energy depletion was the major inducer of HSP72 expression after moderate intensity exercise. Because HSP72 may protect cells against stress, knowledge about their expression may help in planning optimal trainng regimes.

Dry Matter Intake from Parturition to Midlactation

Six years of data from the Purina Research Center were summarized to quantitate relationships among DMI, DIM, BW, and 4% FCM. Cows were fed individually and housed in a tie-stall barn from parturition to 21 wk postpartum. Best overall equation predicting DMI was kg DMI = .008037 × kg BW + .3134 × kg 4% FCM + .2286 × DIM – .002176 × (DIM)2 + .00000705 × (DIM)3, R2 = .64, CV percentage = 11.1. Data were best fit when separate equations were developed for each week postpartum up to 6 wk and then for periods including 6 to 8, 9 to 13, and 14 to 20 wk. The commonly used equation, kg DMI = .02 × kg BW + .33 × kg 4% FCM, overestimated DMI until wk 10 but underestimated DMI thereafter. The NRC multifactor DMI estimates could be lower or higher than equations developed up to wk 8, depending on values chosen within range of several factors. At wk 8 and beyond, NRC estimates were lower than equations developed, even when highest level within range of several factors was chosen. Calculated energy balances resulted in greater and extended energy deficit for cows in their second or later lactation compared with first lactation. Loss of BW alone was a poor indicator of energy status in early lactation.

Nutrition and postpartum rebreeding in cattle.

Body weight and condition score, although perhaps imprecise or subjective, are functional indicators of energy status and rebreeding performance after calving. Inadequate precalving and(or) postcalving energy or protein nutrition lowers pregnancy rates as well as first-service conception rates and extends postpartum intervals in suckled postpartum beef females. Normal nutritional regimens for dairy cows that are fed for maximal lactation do not exhibit long postpartum intervals or reduced fertility. Yet excessive protein intake may depress postpartum rebreeding performance, especially in older dairy cows. Feeding of ionophores, with increased ruminal propionate levels in the rumen, results in an earlier return to estrus postpartum. Underfeeding of the postpartum cow extends the period of ovarian inactivity. The underfed postpartum cow's lack of ovarian activity appears to be due to a suppression of the pulsatile release of LH from the anterior pituitary gland, which in turn is controlled by release of GnRH from the hypothalamus. Some metabolic compound(s) presumably act on the hypothalamic-pituitary-ovarian axis as the nutritional state of the animal is altered.

Food stamps and the energy status of the U.S. elderly poor

The energy status of poor elderly individuals in relation to the nonpoor elderly was examined using data from NHANES I and II. Within the poor population, the status of Food Stamp Program participants was compared with that of nonparticipants. The indicators of energy status used were weight (adjusted for height), triceps skinfold, subscapular skinfold, and energy intake. Energy status was examined by analyses of variance; the effects associated with sex, race, age, geographic region, and other potentially confounding variables were included in the model. In both surveys, there were interactions of income and food stamp use with sex. That is, poor women had greater means for weight and triceps skinfold than the nonpoor. Among the poor women, the Food Stamp Program participants weighed more than the nonparticipants, and their triceps skinfold mean was greater in NHANES II than in NHANES I. The poor men had a lower mean for triceps skinfold than the nonpoor, but there was no difference between the program participants and nonparticipants. Hence, for the poor elderly in NHANES I and II, food stamp use was not consistently associated with differences in energy status, as indicated by weight, skinfold, and energy intake.