Gene expression of hepatic gluconeogenic and fatty acid metabolism in early-lactation dairy cows as affected by dietary starch and monensin supplementation.

Our previously published companion papers demonstrated improved production performance and energetic metabolism in cows fed diets with increased propiogenic potential in early lactation. Study objectives were to further explore effects of dietary starch content and monensin on hepatic gene expression of key enzymes related to gluconeogenesis and fatty acid metabolism in early lactation. From d 1 to 21 postpartum, primiparous (n = 16) and multiparous (n = 33) Holstein cows were fed a high (HS; 26.2% starch, 34.3% neutral detergent fiber, 22.7% acid detergent fiber, 15.5% crude protein) or low (LS; 21.5% starch, 36.9% neutral detergent fiber, 25.2% acid detergent fiber, 15.4% crude protein) starch diet with a daily topdress containing either 0 (Con) or 450 mg/d monensin (Mon). Cows were randomly assigned to treatment. Liver biopsies were obtained from cows on d 7 postpartum for DNA and RNA quantification and mRNA expression analysis. In primiparous cows, Mon supplementation decreased CPT1A expression relative to controls, whereas in multiparous cows Mon increased its expression. Cows fed HS and Mon tended to have decreased HMGCS2 expression relative to cows fed HS and Con. In multiparous cows, Mon supplementation tended to increase PC and PCK1 expression relative to controls. Correlation analysis was performed for all gene expression variables. Overall, relationships were similar in directionality and magnitude between cows fed HS and LS and Con and Mon. However, for cows fed Con there was a positive relationship between HMGCS2 and PC and HMGCS2 and PCK1, whereas for cows fed Mon there was no relationship. There was a similar lack of relationship between HMGCS2 and PC for cows fed HS. Overall, results support changes in performance and energetic metabolism reported in our companion papers, indicating that cows fed diets of different starch content in early lactation with Mon supplementation throughout the transition period had alterations in hepatic gene expression consistent with increased hepatic propionate supply.

Associations of a liver health index with health, milk yield, and reproductive performance in dairy herds in the northeastern United States.

The objective was to evaluate a liver health index (LHI) by evaluating its association with negative health events, milk yield, and risk of pregnancy within 150 d in milk (DIM). In a retrospective cohort study, an LHI was calculated based on plasma albumin, cholesterol, and bilirubin concentrations for 265 primiparous and 611 multiparous cows 3 to 12 DIM enrolled across 72 farms in the northeastern United States. Mixed effects linear regression models were used to evaluate if (1) metritis (MET), (2) displaced abomasum (DA), (3) clinical ketosis (CK), (4) one or more of the 3 disorders (MET, DA, or CK), (5) 2 or more of the 3 disorders (MET, DA, or CK), or (6) culling within 30 DIM was associated with LHI. Mixed effects linear regression models were used to evaluate if LHI was associated with 305-d mature equivalent milk at the fourth test day (ME305; mean ± standard deviation: 114 ± 13 DIM) and a Cox proportional hazards model was used to evaluate if LHI was associated with pregnancy within 150 DIM. Cows that were diagnosed with MET, DA, CK, one or more of the disorders, 2 or more of the disorders, or were culled within 30 DIM had a lower LHI than cows that were not diagnosed with a disorder or culled. A 1-unit increase in LHI was associated with a 154 ± 38 kg increase in ME305 and a 8% increased risk of pregnancy within 150 DIM [hazard ratio (95% confidence interval): 1.08 (1.03 to 1.14)] for multiparous cows; however, we did not identify a relationship between LHI and ME305 or pregnancy within 150 DIM for primiparous cows. These results suggest that the LHI is associated with health, milk yield, and pregnancy within 150 DIM for multiparous cows and health for primiparous cows; therefore, the LHI can be used as a tool to evaluate transition cow success.

Neurogenesis in the neonatal rat hippocampus is regulated by sexually dimorphic epigenetic modifiers.

BACKGROUND: Neurogenesis in the hippocampus endures across the lifespan but is particularly prolific during the first postnatal week in the developing rodent brain. The majority of new born neurons are in the dentate gyrus (DG). The number of new neurons born during the first postnatal week in the DG of male rat pups is about double the number in females. In other systems, the rate of cell proliferation is controlled by epigenetic modifications in stem cells. We, therefore, explored the potential impact of DNA methylation and histone acetylation on cell genesis in the developing DG of male and female rats. METHODS: Cell genesis was assessed by quantification of BrdU + cells in the DG of neonatal rats following injections on multiple days. Methylation and acetylation were manipulated pharmacologically by injection of well vetted drugs. DNA methylation, histone acetylation and associated enzyme activity were measured using commercially available colorimetric assays. mRNA was quantified by PCR. Multiple group comparisons were made by one- or two-way ANOVA followed by post-hoc tests controlling for multiple comparisons. Two groups were compared by t test. RESULTS: We found higher levels of DNA methylation in male DG and treatment with the DNA methylating enzyme inhibitor zebularine reduced the methylation and correspondingly reduced cell genesis. The same treatment had no impact on either measure in females. By contrast, treatment with a histone deacetylase inhibitor, trichostatin-A, increased histone acetylation in the DG of both sexes but increased cell genesis only in females. Females had higher baseline histone deacetylase activity and greater inhibition in response to trichostatin-A treatment. The mRNA levels of the proproliferative gene brain-derived neurotrophic factor were greater in males and reduced by inhibiting both DNA methylation and histone deacetylation only in males. CONCLUSIONS: These data reveal a sexually dimorphic epigenetically based regulation of neurogenesis in the DG but the mechanisms establishing the distinct regulation involving DNA methylation in males and histone acetylation in females is unknown.

Effects of prepartum diets varying in dietary energy density and monensin on early-lactation performance in dairy cows.

Our objectives were to evaluate the effects of prepartum monensin supplementation and dry-period nutritional strategy on the postpartum productive performance of cows fed monensin during lactation. A total of 102 Holstein cows were enrolled in the experiment (32 primiparous and 70 multiparous). The study was a completely randomized design, with randomization restricted to balance for parity, body condition score, and expected calving date. A 2 × 2 factorial arrangement of prepartum treatments was used; the variables of interest were prepartum feeding strategy [controlled-energy diet throughout the dry period (CE) vs. controlled-energy diet from dry-off to 22 d before expected parturition, followed by a moderate-energy close-up diet from d 21 before expected parturition through parturition (CU)] and prepartum monensin supplementation [0 g/t (control, CON) or 24.2 g/t (MON); Rumensin; Elanco Animal Health, Greenfield, IN]. Lactation diets before and after the dry period contained monensin at 15.4 g/t. During the close-up period, cows fed CU had greater DM and NEL intakes than cows fed CE. Calf BW at birth tended to be greater for cows fed CU than for those fed CE but was not affected by MON supplementation. Diet did not affect calving difficulty score, but cows supplemented with MON had an increased calving difficulty score. We found a tendency for a MON × parity interaction for colostral IgG concentration, such that multiparous MON cows tended to have lower IgG concentration than CON cows, but colostral IgG concentration for primiparous MON and CON cows did not differ. Postpartum milk yield did not differ between diets but tended to be greater for cows supplemented with MON. Milk fat and lactose content were greater for cows fed CU than for those fed CE, and lactose content and yield were increased for cows supplemented with MON. Solids-corrected and fat-corrected milk yields were increased by MON supplementation, but were not affected by diet. Overall means for postpartum DMI did not differ by diet or MON supplementation. The CU diet decreased the concentration of nonesterified fatty acids during the close-up period but increased it postpartum. Neither diet nor monensin affected ß-hydroxybutyrate or liver composition. Overall, postpartum productive performance differed little between prepartum dietary strategies, but cows fed MON had greater energy-corrected milk production. In herds fed monensin during lactation, monensin should also be fed during the dry period.

Short communication: Model for metritis severity predicts that disease misclassification underestimates projected milk production losses.

The objective of this research was to determine the effect of disease misclassification on the estimated effect of metritis on milk production. Misclassification introduces bias that usually results in an underestimation of the association between exposure (disease) and the outcome of interest (milk production). This distorted measure of association results from the comparison of an affected population (some of which may not truly be affected) to a nonaffected population (which often includes affected subjects that are unidentified). A convenience sample of DairyComp305 (Valley Agricultural Software, Tulare, CA) data representing 1 yr of calvings (n = 3,277) from 1 Midwestern Holstein herd was used. This herd was chosen because of its ongoing efforts to consistently and completely record all clinical diseases, including the incidence of both mild and severe metritis cases. Metritis was defined as the presence of a flaccid uterus containing fetid fluids or a foul watery discharge within 14 d of calving. Cows that appeared clinically normal other than the discharge were considered mild and those with systemic signs of disease were classified as severe. The original data set included metritis recorded as mild, severe, or not recorded (NR), where no metritis was observed, and was considered to contain the metritis true severity (TrS). First, to evaluate the effect of misclassification bias, we retrospectively randomized 45% of mild metritis to be classified as NR to simulate inconsistent disease recording (IR); then, in a separate model, all mild metritis cases were changed to NR to simulate a situation of very poor disease recording (PR), where only the most severe cases are recorded. The TrS, IR, and PR data sets were analyzed separately in JMP (SAS Institute Inc., Cary, NC). An ANOVA was conducted for second test 305-d mature-equivalent milk projection (2nd305ME), and nonsignificant variables were removed, but the variable metritis was forced into all models. Based upon the TrS model, adjusting for effects of lactation group, month of calving, dystocia, twins, retained placenta, early-lactation mastitis, displaced abomasum, and significant interactions, a case of mild metritis was associated with 384 kg less 2nd305ME and a case of severe metritis was associated with 847 kg less 2nd305ME compared with no metritis. For the IR model, a case of mild metritis was associated with 315 kg less 2nd305ME and a case of severe metritis was associated with 758 kg less 2nd305ME compared with no metritis. For the PR model, severe metritis was associated with 680 kg less 2nd305ME compared with NR. The IR and PR models underestimated 2nd305ME loss for severe metritis cases by 89 and 166 kg/cow, and resulted in 180,441 and 330,256 kg of total milk loss unaccounted for at the herd level, respectively, compared with TrS. Overall, misclassification of metritis cases results in greater bias and largely underestimates the true association between metritis and the consequence costs of the disease.

Short communication: Field study to investigate the associations between herd-level risk factors for milk fat depression and bulk tank milk fat percent in dairy herds feeding monensin.

Fat is the most variable milk component, and maintaining milk fat continues to be a challenge on commercial dairy farms. Our objectives were to establish associations between herd-level risk factors for milk fat depression and bulk tank milk fat content in commercial dairy herds feeding monensin. Seventy-nine Holstein commercial dairy herds in the northeast and Upper Midwest United States were enrolled in an observational study. Data were collected on herd characteristics, total mixed ration (TMR) samples, all component silage samples, and bulk tank milk samples. The unconditional univariable association of each explanatory variable and bulk tank milk fat percentage was evaluated using simple linear regression and multivariable regression models. Milk fat content of trans-10 C18:1 had an exponentially negative relationship to herd milk fat percentage. In general, milk fat content of fatty acids synthesized de novo in the mammary gland were positively related to herd milk fat, and the content of several trans-C18:1 fatty acids, which would be products of alternate pathways of ruminal biohydrogenation, were negatively related to herd milk fat. Variables related to TMR composition did not have univariable relationships with herd milk fat percentage. Herds that had >49.8% of the TMR particles on the middle screen of the Penn State particle separator had higher milk fat percentage than those with ≤49.8%, and herds with >54.0% of TMR particles in the bottom pan had lower milk fat percentage than herds with ≤54.0%. Dietary content of monounsaturated fatty acids (C16:1 and C18:1) had negative relationships with herd milk fat percentage; however, no single diet component accounted for more than 11% of the variation in herd-level milk fat percentage. Univariable monensin dose was not associated with herd milk fat percentage. The relative lack of significant univariate relationships with herd-level milk fat suggests many factors contribute to milk fat content, and herds experiencing low milk fat will need to examine many potential risk factors when working to troubleshoot this challenge.

Effect of abomasal carbohydrates and live yeast on measures of postruminal fermentation.

Two studies were conducted to evaluate the effects of abomasal carbohydrate infusion on nutrient digestibility and fecal measures. In Exp. 1, 5 Holstein steers were assigned to a Latin square with 1-wk periods and were abomasally infused on a single day at the end of each period with water alone, a single pulse dose of water with 1 g/kg BW oligofructose or cornstarch, or 4 pulse doses of water with 0.25 g/kg BW oligofructose or cornstarch administered every 6 h. Total tract nutrient digestibility was not affected by treatment except for a tendency for a decrease in starch digestibility in response to the 1 g/kg BW dose of cornstarch ( < 0.10). Compared with the control, both oligofructose and starch infusions caused similar decreases in fecal pH ( < 0.05) and increases in fecal short-chain fatty acids ( ≤ 0.01) measured 12 h after the first infusion, with the single 1 g/kg BW infusions causing a greater magnitude of pH change compared with the four 0.25-g/kg BW infusions ( < 0.01). All treatments increased concentration of fecal lipopolysaccharide compared with the control for at least 1 time point following the infusion ( < 0.05), with a greater increase observed for the 0.25 g/kg BW infusions of oligofructose compared with the other treatments ( < 0.05). Results of Exp. 1 indicate that both oligofructose and cornstarch infusions increased carbohydrate fermentation in the intestines and can be used as a method to evaluate the impact of excessive intestinal fermentation on intestinal health. In Exp. 2, 6 Holstein steers received abomasal pulse doses of 0 (control) or 10 g/d live var. (SB) according to a crossover design with 18-d periods. Abomasal infusions of 4 pulse doses of 0.25 g/kg BW oligofructose administered every 6 h were conducted on d 16 of each period. During the baseline period prior to the oligofructose challenge, there were no effects of SB on fecal measures except for an increase in apparent total tract NDF digestibility ( < 0.05), suggesting that SB increased intestinal fiber fermentation. During the oligofructose challenge, SB increased fecal score ( = 0.03) and tended to reduce fecal short-chain fatty acids ( = 0.10). Results of Exp. 2 suggest that abomasal SB modestly stabilized the intestinal environment during increased carbohydrate fermentation.

Associations between the degree of early lactation inflammation and performance, metabolism, and immune function in dairy cows.

The objective of the current study was to determine associations between the severity of systemic inflammation during the early postpartum period and performance, energy metabolism, and immune function in dairy cows. Cows were assigned to categorical quartiles (Q; Q1=0.18-0.59, Q2=0.60-1.14, Q3=1.15-2.05, and Q4=2.06-2.50 g of haptoglobin/L) based on the highest plasma haptoglobin (Hp) concentration measured during wk 1 postpartum. Although cows were assigned to different categories of inflammation during the postpartum period, we detected a quadratic relationship of inflammation on prepartum dry matter intake (DMI) and body weight (BW) such that cows in Q2 had lower prepartum DMI and cows in Q2 and Q3 had lower prepartum BW compared with cows in the other quartiles. We also detected a quadratic association of inflammation with postpartum DMI and BW such that cows in Q2 and Q3 also had generally lower postpartum DMI and BW compared with cows in Q1. There was a tendency for a Q × time interaction for milk yield and Q × time interactions for 3.5% fat-corrected milk and energy-corrected milk yields; quadratic relationships suggested decreased milk yield for Q2 and Q3 cows. We also found Q × parity and Q × time interactions for plasma glucose and insulin concentrations, suggesting alterations with differing degrees of inflammation. There was also a Q × time interaction for plasma nonesterified fatty acids concentration. In addition, alterations in liver triglyceride and glycogen contents for cows with inflammation as well as alterations in [1-(14)C]propionate oxidation in vitro were observed. Although we observed limited effects of inflammation on neutrophil and monocyte phagocytosis at d 7 postpartum, inflammation appeared to alter neutrophil and monocyte oxidative burst. Overall, cows with any degree of elevated haptoglobin in the first week after calving had alterations in both pre- and postpartum intake and postpartum metabolism.

Effects of monensin and starch level in early lactation diets on indices of immune function in dairy cows.

The objective of this study was to evaluate the effect of dietary starch level and monensin on immune function. Prior to parturition, primiparous (n=21) and multiparous (n=49) Holstein cows were fed a common controlled energy close-up diet with a daily topdress of either 0 or 400 mg/d monensin. From 1 to 21 d in milk (DIM), cows were fed a high-starch (HS; 26.2% starch) or low-starch (LS; 21.5% starch) total mixed ration with a daily topdress of either 0 or 450 mg of monensin/d continuing with prepartum topdress assignment. From 22 through 63 DIM, all cows were fed HS and continued with assigned topdress treatment until 63 DIM. Endometrial cytology and whole-blood immune function were assessed at 8 DIM and on 1 d between 40 and 60 DIM. At 8 DIM, cows fed HS had an increased percentage (%) of phagocytic monocytes and tended to have a greater phagocytosis index (% of positive cells × mean fluorescence intensity) in monocytes compared with cows fed LS. At 8 DIM, cows fed HS also tended to have a higher percentage of monocytes involved in oxidative burst and a higher monocyte oxidative burst index compared with LS cows. At 8 DIM, blood polymorphonuclear neutrophils (PMN) isolated from cows fed monensin during the periparturient period tended to have higher PMN glycogen content compared with control cows. At 40 to 60 DIM, the incidence of cytological endometritis as diagnosed by uterine cytology was not affected by dietary treatment. However, at 40 to 60 DIM, cows fed monensin had an increased percentage of Escherichia coli-stimulated PMN, tended to have a greater percentage of monocytes involved in oxidative burst, and tended to have an increased E. coli-stimulated monocyte oxidative burst index. At 40 to 60 DIM, blood PMN isolated from cows fed HS during early lactation had higher PMN glycogen content compared with cows fed LS during early lactation. Overall, results suggest that feeding higher starch diets postpartum and peripartal supplementation with monensin may have some beneficial effects on immune function, although uterine cytology was not affected by treatment.

Associations between hepatic metabolism of propionate and palmitate in liver slices from transition dairy cows.

Multiparous Holstein cows (n=95) were used to evaluate changes in hepatic propionate and palmitate metabolism and liver composition over time during the transition period, along with the relationships of these variables with cumulative increases in nonesterified fatty acids and ß-hydroxybutyrate during the periparturient period. Data from 3 previous experiments were used to address the study objectives, accounting for a total of 95 multiparous Holstein cows. Liver slices from biopsies on d -21, 1, and 21 relative to parturition were used to determine conversion of [1-(14)C]palmitate to CO2 and esterified products (EP) and the conversion of [1-(14)C]propionate to CO2 and glucose. Hepatic glycogen content was highest on d -21 and was 26.9 and 36.5% of prepartum values on d 1 and 21, respectively. Liver triglyceride content was lowest at d -21 and was 271 and 446% of prepartum values on d 1 and 21, respectively. We detected no difference in the capacity for the liver to oxidize [1-(14)C]palmitate to CO2 between d -21 and d 1; however, on d 21, oxidation was 84% of prepartum values. The capacity of the liver to convert [1-(14)C]palmitate to EP was 148 and 139% of prepartum values on d 1 and 21, respectively. The capacity of liver to convert [1-(14)C]propionate to CO2 was 127 and 83% of prepartum values on d 1 and 21, and the capacity of liver to convert [1-(14)C]propionate to glucose was 126 and 85% of prepartum values on d 1 and 21, respectively. Correlation relationships suggest that overall, cows with elevated prepartum liver triglyceride content had elevated triglycerides throughout the transition period along with increased [1-(14)C]palmitate oxidation and conversion to EP and a decreased propensity to convert [1-(14)C]propionate to glucose. Cows with increased [1-(14)C]propionate oxidation had increased conversion of [1-(14)C]propionate to glucose throughout the transition period. Overall, conditions that lead to impairments in fatty acid metabolism during the transition period appear to be associated with impaired postpartum hepatic propionate metabolism.

Short communication: concentrations of nonesterified fatty acids and ß-hydroxybutyrate in dairy cows are not well correlated during the transition period.

The objective was to use longitudinal data of blood nonesterified fatty acids (NEFA) and ß-hydroxybutyrate (BHBA) concentrations to describe the relationship between NEFA and BHBA in dairy cows during the periparturient period. Blood NEFA and BHBA concentration data collected from d 21 prepartum to 21 postpartum for 269 multiparous Holstein cows were selected from 4 different studies carried out within our research groups. Overall, NEFA concentrations were increased beginning near parturition with a relatively steady elevation of NEFA through d 9, after which concentrations gradually decreased. Prepartum BHBA concentrations began to increase beginning several days before parturition, continued to increase during the first week after parturition, and remained elevated through d 21 postpartum. Of the 269 cows included in the data set, 117 cows (43.5%) had at least one postpartum hyperketonemic event (BHBA ≥1.2mmol/L), and 202 cows (75.1%) had at least one event of elevated postpartum NEFA concentrations (≥0.70mmol/L) between 3 and 21 d in milk. Area under the curve (AUC) was used to investigate relationships between metabolites over time. Overall, the correlations between transition period NEFA and BHBA AUC were weak. We detected a negative correlation between prepartum BHBA AUC and postpartum NEFA AUC (r=-0.26). A positive correlation existed between postpartum NEFA AUC and postpartum BHBA AUC; however, the correlation coefficient was low (r=0.26). Large variation was found between the day of maximum NEFA concentration within the first 21 d in milk and day of maximum BHBA concentration for the same period. The mean and median times of maximum NEFA concentration were 6.8 and 6 d, respectively, whereas the mean and median times of maximum BHBA were 9.6 and 8 d, respectively; however, the range in days for both the mean and median day of maximum concentrations was very large. Overall, our data set indicates a weak relationship between blood concentrations of NEFA and BHBA during the periparturient period of dairy cows, suggesting that elevated concentrations of one should not be extrapolated to suggest elevated concentrations of the other metabolite.

Performance of early-lactation dairy cows as affected by dietary starch and monensin supplementation.

The objective of this study was to evaluate the effect of postpartum dietary starch content and monensin supplementation throughout the periparturient period and into early lactation on production performance of dairy cows during early lactation. Prior to parturition, primiparous (n=21) and multiparous (n=49) Holstein cows were fed a common controlled-energy close-up diet with a daily topdress of either 0 or 400mg/d monensin. From d 1 to 21 postpartum, cows were fed a high-starch (HS; 26.2% starch, 34.3% NDF, 22.7% ADF, 15.5% CP) or low-starch (LS; 21.5% starch, 36.9% NDF, 25.2% ADF, 15.4% CP) total mixed ration with a daily topdress of either 0mg/d of monensin or 450mg/d monensin (MON), continuing with prepartum topdress treatment assignment. From d 22 through 63 postpartum, cows were fed HS and continued with their assigned daily topdress. Interactions of starch content and MON supplementation were not significant for any of the variables measured. Cows fed HS from wk 1 to 3 postpartum had higher early-lactation milk yields (starch × week interaction) compared with LS cows, but HS cows also had lower percentages of milk fat, true protein, lactose, and total solids during the same period, resulting in similar yields of energy-corrected milk (ECM) between starch treatments. Cows fed HS had higher early-lactation dry matter intake (DMI; starch × week interaction) and lost less body condition score during wk 1 to 3, contributing to improved energy balance postpartum. No effect of starch treatment was observed on apparent total-tract dry matter or starch digestibilities assessed during d 18 to 19 (±2) postpartum, although cows fed the LS diet had greater apparent total-tract NDF digestibility compared with cows fed the HS diet. Cows fed MON had higher DMI and higher milk yields during the first 9 wk of lactation. However, all cows had similar yields of ECM because of trends for lower milk fat content during early lactation. In part because of similar yields of ECM between these treatments and higher DMI for cows fed MON, ECM per DMI during the first 9 wk of lactation was not affected by MON treatment. There was no effect of MON treatment on apparent total-tract dry matter, NDF, or starch digestibilities. Overall, cows fed more propiogenic diets in early lactation (HS or MON) had increased milk yield and DMI during the immediate postpartum period, indicating that diets with greater propiogenic capacity do not have detrimental effects on early-lactation DMI.

Metabolism of early-lactation dairy cows as affected by dietary starch and monensin supplementation.

The objective of this study was to evaluate the effect of dietary starch content and monensin (MON) on metabolism of dairy cows during early lactation. Before parturition, primiparous (n=21) and multiparous (n=49) Holstein cows were fed a common controlled-energy close-up diet with a daily topdress of either 0 or 400mg/d monensin. From d 1 to 21 postpartum, cows were fed a high-starch (HS; 26.2% starch, 34.3% neutral detergent fiber, 22.7% acid detergent fiber, 15.5% crude protein) or low-starch (LS; 21.5% starch, 36.9% neutral detergent fiber, 25.2% acid detergent fiber, 15.4% crude protein) total mixed ration with a daily topdress of either 0mg/d monensin (CON) or 450mg/d monensin (MON), continuing with prepartum topdress assignment. From d 22 through 63 postpartum, all cows were fed HS and continued with the assigned topdress treatment until d 63. Cows fed HS had higher plasma glucose and insulin and lower nonesterified fatty acids (NEFA) than cows fed LS during d 1 to 21 postpartum. Cows fed LS had elevated early-lactation ß-hydroxybutyrate (BHBA) compared with cows fed HS. Cows fed HS had greater insulin resistance and increased plasma haptoglobin in the early lactation period. There was no effect of MON on postpartum plasma NEFA. Cows fed MON had higher plasma glucose compared with CON cows, which was driven by a MON × parity interaction in which primiparous cows fed MON had greater plasma glucose concentrations than cows fed CON. Cows fed MON had lower plasma BHBA compared with CON, which was contributed to by a MON × parity interaction in which primiparous cows fed MON had lower BHBA concentrations than CON. Starch treatment had no effect on overall liver triglyceride content. Primiparous cows fed MON had increased liver triglyceride content compared with CON primiparous cows, and multiparous cows fed MON had decreased liver triglyceride content compared with CON cows. Multiparous cows fed LS with MON had higher liver glycogen content than multiparous cows fed the LS without MON, with no effect of MON treatment for multiparous cows fed HS. There was no effect of starch or MON treatment on liver capacity to oxidize propionate to CO2, and effects of starch on gluconeogenesis were not significant. Cows fed MON tended to have greater capacity to convert propionate to glucose than CON. Supplementation with MON increased the ratio of glucose to CO2, which indicated that cows fed MON had a greater propensity to convert propionate to glucose. Overall, cows fed more propiogenic diets in early lactation (high starch or monensin) exhibited improved energy metabolism during early lactation.

Sex- and age-dependent effects of androgens on glutamate-induced cell death and intracellular calcium regulation in the developing hippocampus.

Hippocampal neurons must maintain control over cytosolic calcium levels, especially during development, as excitation and calcium flux are necessary for proper growth and function. But excessive calcium can lead to excitotoxic cell death. Previous work suggests that neonatal male and female hippocampal neurons regulate cytosolic calcium differently, thereby leading to differential susceptibility to excitotoxic damage. Hippocampal neurons are also exposed to gonadal hormones during development and express high levels of androgen receptors. Androgens have both neuroprotective and neurotoxic effects in adults and developing animals. The present study sought to examine the effect of androgen on cell survival after an excitatory stimulus in the developing hippocampus, and whether androgen-mediated calcium regulation was the governing mechanism. We observed that glutamate did not induce robust or sexually dimorphic apoptosis in cultured hippocampal neurons at an early neonatal time point, but did 5days later - only in males. Further, pretreatment with the androgen dihydrotestosterone (DHT) protected males from apoptosis during this time, but had no effect on females. Calcium imaging of sex-specific cultures revealed that DHT decreased the peak of intracellular calcium induced by glutamate, but only in males. To determine a possible mechanism for this androgen neuroprotection and calcium regulation, we quantified three calcium regulatory proteins, plasma membrane calcium ATPase1 (PMCA1), sodium/calcium exchanger1 (NCX1), and the sarco/endoplasmic reticulum calcium ATPase 2 (SERCA2). Surprisingly, there was no sex difference in the level of any of the three proteins. Treatment with DHT significantly decreased PMCA1 and NCX1, but increased SERCA2 protein levels in very young animals but not at a later timepoint. Taken together, these data suggest a complex interaction of sex, hormones, calcium regulation and developmental age; however androgens acting during the first week of life are implicated in regulation of hippocampal cell death and may be an underlying mechanism for sexually dimorphic apoptosis.

Brain activation by an olfactory stimulus paired with juvenile play in female rats.

We have previously shown that reward experienced during social play at juvenile age can be paired with artificial odors, and later in adulthood facilitate olfactory conditioned partner preferences (PP) in female rats. Herein, we examined the expression of FOS immunoreactivity (FOS-IR) following exposure to the odor paired with juvenile play (CS+). Starting at day P31 females received daily 30-min periods of social play with lemon-scented (paired group) or unscented females (unpaired group). At day P42, they were tested for play-PP with two juvenile males, one bearing the CS+ (lemon) and one bearing a novel odor (almond). Females were ovariectomized, hormone-primed and at day P55 tested for sexual-PP between two adult stud males scented with lemon or almond. In both tests, females from the paired group displayed conditioned PP (play or sexual) toward males bearing the CS+. In the present experiments females were exposed at day P59 to the CS+ during 60 min and their brains processed for FOS-IR. One group of female rats (Play+Sex) underwent play-PP and sexual-PP, whereas a second group of females (Play-only) underwent exclusively play-PP but not sexual-PP. Results showed that in the Play-only experiment exposure to the CS+ induced more FOS-IR in the medial prefrontal cortex, orbitofrontal cortex, dorsal striatum, and ventral tegmental area as compared to females from the unpaired group. In the Play+Sex experiment, more FOS-IR was observed in the piriform cortex, dorsal striatum, lateral septum, nucleus accumbens shell, bed nucleus of the stria terminalis and medial amygdala as compared to females from the unpaired group. Taken together, these results indicate mesocorticolimbic brain areas direct the expectation and/or choice of conditioned partners in female rats. In addition, transferring the meaning of play to sex preference requires different brain areas.

Epigenetic contributions to hormonally-mediated sexual differentiation of the brain.

It has been long established that hormones exert enduring influences on the developing brain that direct the reproductive response in adulthood, although the cellular mechanisms by which organisational effects are maintained have not been determined satisfactorily. Recent interest in epigenetic modifications to the nervous system has highlighted the potential for hormone-induced changes to the genome that could endure for the lifespan but not be transmitted to the next generation. Preliminary evidence suggests that this is indeed possible because sex differences in the histone code and in the methylation of CpGs in the promoters of specific genes have been identified and, at times, functionally correlated with behaviour. The present review provides an overview of epigenetic processes and discusses the current state-of-the-art, and also identifies future directions.

The effect of an exogenous amylase on performance and total-tract digestibility in lactating dairy cows fed a high-byproduct diet.

The objective of this experiment was to determine the performance and digestibility response of lactating dairy cows fed a reduced-starch diet containing a commercial amylase product. Treatments consisted of a normal-starch total mixed ration (NS-), a reduced-starch total mixed ration (RS-), and a reduced-starch total mixed ration with exogenous amylase (RS+) added to the concentrate. Treatments were assigned according to a replicated 3 × 3 Latin square design with 28-d periods. Twenty-three cows completed the study. Starch concentrations in NS-, RS-, and RS+ total mixed rations were 27.7, 23.5, and 22.7%, respectively. Effects of treatment on intake, milk production, milk composition, and total-tract apparent nutrient digestibility were evaluated during the last week of each period. Effects of amylase on in vitro starch digestibility of the NS- and RS- grain mixes were also measured. We hypothesized that the reduction in dietary starch in the RS- ration would decrease diet digestibility and limit milk production compared with NS- due to a decrease in available energy, and that RS+ would alleviate some of this decrease by increasing nutrient digestibility. Contrary to this hypothesis, the RS- diet did not affect intake or milk production relative to the NS- diet, except for increased milk urea nitrogen and a tendency for a decrease in milk protein yield. This lack of response is attributed to both low milk fat concentrations across treatments and greater than predicted dietary energy content preventing the energy deficit that was intended to occur with the reduced-starch rations. Cows fed the RS+ ration had the lowest production performance, with reduced milk, fat-corrected milk, protein, and lactose yields relative to cows fed NS-. Cows fed RS+ also had reduced lactose yield and tended to have reduced milk and fat-corrected milk relative to cows fed RS-. Despite the negative effects of the RS+ treatment on performance, exogenous amylase did increase both in vitro and in vivo measurements of digestibility. Although amylase increased nutrient digestibility, this did not translate into improved milk performance, likely due to the relatively high energy content of experimental diets compared with cow requirements.

Complications after patello-femoral versus total knee replacement in the treatment of isolated patello-femoral osteoarthritis. A meta-analysis.

PURPOSE: Both patellofemoral arthroplasty (PFA) and total knee arthroplasty (TKA) are successful in treating isolated patellofemoral osteoarthritis, but the complication rates after PFA are concerning. We performed a meta-analysis to compare the incidence of complications, re-operations, and revision following PFA and TKA for patellofemoral osteoarthritis. METHODS: We systematically identified publications with patients who underwent PFA or TKA for patellofemoral osteoarthritis with minimum 1.5 year follow-up. Demographics, implant (TKA, first [1G] or second-generation [2G] PFA), complications, and cause of re-operations were extracted. Random-effects meta-analysis was used to pool incidence data, which was compared between groups using logistic regression to adjust for length of follow-up. RESULTS: Twenty-eight observational studies and no randomized trials were included in this meta-analysis, which limits its generalizability. There was a higher likelihood of any re-operation (odds ratio 8.06) and revision (OR 8.11) in PFA compared to TKA. Re-operation (OR 4.33) and revision (OR 4.93) were more likely in 1G-PFA than 2G-PFA. When comparing 2G-PFA to TKA, there was no significant difference in re-operation, revision, pain, or mechanical complications. CONCLUSIONS: Patients who undergo PFA rather than TKA are more likely to experience complications and require re-operation or revision, but subgroup analysis suggests a relation to implant design. There is no significant difference in re-operation, revision, pain, or mechanical complications between 2G-PFA and TKA. LEVEL OF EVIDENCE: Systematic review of Level III therapeutic studies, Level III.

Milestones on Steroids and the Nervous System: 10 years of basic and translational research.

During the last 10 years, the conference on 'Steroids and Nervous System' held in Torino (Italy) has been an important international point of discussion for scientists involved in this exciting and expanding research field. The present review aims to recapitulate the main topics that have been presented through the various meetings. Two broad areas have been explored: the impact of gonadal hormones on brain circuits and behaviour, as well as the mechanism of action of neuroactive steroids. Relationships among steroids, brain and behaviour, the sexual differentiation of the brain and the impact of gonadal hormones, the interactions of exogenous steroidal molecules (endocrine disrupters) with neural circuits and behaviour, and how gonadal steroids modulate the behaviour of gonadotrophin-releasing hormone neurones, have been the topics of several lectures and symposia during this series of meetings. At the same time, many contributions have been dedicated to the biosynthetic pathways, the physiopathological relevance of neurosteroids, the demonstration of the cellular localisation of different enzymes involved in neurosteroidogenesis, the mechanisms by which steroids may exert some of their effects, both the classical and nonclassical actions of different steroids, the role of neuroactive steroids on neurodegeneration, neuroprotection, and the response of the neural tissue to injury. In these 10 years, this field has significantly advanced and neuroactive steroids have emerged as new potential therapeutic tools to counteract neurodegenerative events.

Striatal origin of the pathologic beta oscillations in Parkinson's disease.

Enhanced oscillations at beta frequencies (8-30 Hz) are a signature neural dynamic pathology in the basal ganglia and cortex of Parkinson's disease patients. The mechanisms underlying these pathological beta oscillations remain elusive. Here, using mathematical models, we find that robust beta oscillations can emerge from inhibitory interactions between striatal medium spiny neurons. The interaction of the synaptic GABAa currents and the intrinsic membrane M-current promotes population oscillations in the beta frequency range. Increased levels of cholinergic drive, a condition relevant to the parkinsonian striatum, lead to enhanced beta oscillations in the striatal model. We show experimentally that direct infusion of the cholinergic agonist carbachol into the striatum, but not into the neighboring cortex, of the awake, normal rodent induces prominent beta frequency oscillations in the local field potential. These results provide evidence for amplification of normal striatal network dynamics as a mechanism responsible for the enhanced beta frequency oscillations in Parkinson's disease.