Effects of supplementing rumen-protected arginine on performance of transition cows.

An experiment was conducted to determine the effects of supplementing rumen-protected arginine (RPA) on productive performance in dairy cows. One-hundred and 2 cows were blocked by parity and then by energy-corrected milk (ECM) yield. Within block, cows were randomly assigned to control (CON) that received 200 g/d of a mixture of hydrogenated soybean oil and heat-treated soybean meal to supply 30 g of metabolizable protein (MP), or 200 g/d of a product containing 30 g of metabolizable arginine (RPA), which increased the dietary arginine from 5.7 to 7.5% of the MP from 250 d of gestation to 21 d postpartum. After 21 d postpartum, cows were fed the same diet and data were collected until 84 d postpartum. Cows fed RPA produced an additional 2.5 kg of colostrum (5.3 vs. 7.8 ± 1.0 kg) and 220 g more immunoglobulin G (526 vs. 746 ± 93 g) than CON cows. Supplementing RPA increased the yields of milk (32.8 vs. 34.9 ± 1.0 kg/d), ECM (37.8 vs. 40.9 ± 1.2 kg/d), and milk total solids (4.48 vs. 4.86 ± 0.14 kg/d) in the first 21 DIM. The benefits of RPA extended beyond the period of supplementation, with a 6.4% increase in yield of ECM per kg of dry matter consumed in all cows (1.88 vs. 2.00 ± 0.05 kg/kg) and an increase in ECM yield, but only in parous cows (44.2 vs. 48.5 ± 1.5 kg/d). Feeding RPA increased the concentrations of urea N in plasma pre- (12.5 vs. 13.9 ± 0.4 mg/dL) and postpartum (11.6 vs. 13.2 ± 0.4 mg/dL), and in milk during the first 21 d postpartum (11.0 vs. 12.0 ± 0.3 mg/dL). Treatment did not affect the concentrations of AA in plasma prepartum, but feeding RPA tended to increase citrulline (72.5 vs. 77.5 ± 2.7 µM), whereas RPA either tended to decrease isoleucine (129.5 vs. 120.9 ± 5.7 µM) or decreased the concentrations of leucine (181.3 vs. 170.2 ± 6.4 µM) and valine (293.2 vs. 276.7 ± 10.4 µM) postpartum. Feeding RPA increased the relative expression of transcripts involved in AA transport (SLC38A4), urea cycle (ARG1), and gluconeogenesis (PC, PEPCK, and G6PC) in hepatic tissue. Feeding diets to supply additional arginine as RPA during the transition period benefited productive performance in dairy cows that extended beyond the period of supplementation despite minor changes in plasma AA concentrations.

Dietary supplementation of rumen native microbes improves lactation performance and feed efficiency in dairy cows.

The objectives of this study were to determine the effects of 2 dietary microbial additives on productive performance and feed efficiency when supplemented to diets of Holstein cows. One hundred seventeen Holstein cows were enrolled at 61 d (31-87 d) postpartum in a randomized complete block design experiment. Cows were blocked by parity group, as nulliparous or multiparous cows and, within parity, by pretreatment ECM yield. Within block, cows were randomly assigned to one of 3 treatments administered as top-dress for 140 d. Treatments consisted of either 100 g of corn meal containing no microbial additive (CON; 15 primiparous and 25 multiparous), 100 g of corn meal containing 5 g of a mixture of Clostridium beijerinckii and Pichia kudriavzevii (G1; 4 × 107 cfu of C. beijerinckii and 1 × 109 cfu of P. kudriavzevii; 14 primiparous and 24 multiparous), or 100 g of corn meal containing 5 g of a mixture of C. beijerinckii, P. kudriavzevii, Butyrivibrio fibrisolvens, and Ruminococcus bovis (G2; 4 × 107 cfu of C. beijerinckii, 1 × 109 cfu of P. kudriavzevii, 1 × 108 cfu of B. fibrisolvens, and 1 × 108 cfu of R. bovis; 15 primiparous and 24 multiparous). Intake of DM, milk yield, and BW were measured daily, whereas milk composition was analyzed at each milking 2 d a week, and body condition was scored twice weekly. Milk samples were collected on d 60 and 62 in the experiment and analyzed for individual fatty acids. The data were analyzed with mixed-effects models with orthogonal contrast to determine the effect of microbial additive (MA; CON vs. 1/2 G1 + 1/2 G2) and type of microbial additive (TMA; G1 vs. G2). Results are described in sequence as CON, G1, and G2. Intake of DM (22.2 vs. 22.4 vs. 22.4 kg/d), BW (685 vs. 685 vs. 685 kg) and the daily BW change (0.40 vs. 0.39 vs. 0.39 kg/d) did not differ among treatments; however, feeding MA tended to increase BCS (3.28 vs. 3.33 vs. 3.36). Supplementing MA increased yields of milk (39.9 vs. 41.3 vs. 41.5 kg/d), ECM (37.9 vs. 39.3 vs. 39.9 kg/d), fat (1.31 vs. 1.37 vs. 1.40 kg/d), TS (4.59 vs. 4.75 vs. 4.79 kg/d), and ECM per kg of DMI (1.72 vs. 1.76 vs. 1.80 kg/kg). Furthermore, cows fed MA increased yields of preformed fatty acids in milk fat (>16C; 435 vs. 463 vs. 488 g/d), particularly UFA (367 vs. 387 vs. 410 g/d), such as linoleic (C18:2 cis-9,cis-12; 30.9 vs. 33.5 vs. 35.4 g/d) and α-linolenic acids (C18:3 cis-9,cis-12,cis-15; 2.46 vs. 2.68 vs. 2.82 g/d) on d 60 and 62 in the experiment. Collectively, supplementing G1 and G2 improved productive performance of cows with no differences between the 2 MA.

Rumen-protected choline reduces hepatic lipidosis by increasing hepatic triacylglycerol-rich lipoprotein secretion in dairy cows.

Objectives were to determine the effects of supplementing rumen-protected choline (RPC) on hepatic composition and secretion of triacylglycerol-rich lipoprotein when cows were subjected to feed restriction to develop fatty liver. It was hypothesized that RPC reduces hepatic triacylglycerol by enhancing secretion of hepatic lipoprotein. Pregnant, nonlactating parous Holstein cows (n = 33) at mean (± standard deviation) 234 ± 2.2 d of gestation were blocked by body condition (3.79 ± 0.49) and assigned to receive 0 g/d (CON), 25.8 g/d choline ion from a RPC product containing 28.8% choline chloride (CC; treatment L25.8), or 25.8 g/d of choline ion from a RPC product containing 60.0% CC (H25.8). Cows were fed for ad libitum intake for the first 5 d and restricted to 41% of the net energy for lactation required for maintenance and pregnancy from d 6 to 13. Intake of metabolizable methionine was maintained at 18 g/d during feed restriction by supplying rumen-protected methionine. Hepatic tissue was sampled on d 6 and 13 and analyzed for triacylglycerol and glycogen, and mRNA expression of hepatic tissue was investigated. On d 14, cows were not fed and received a 10% solution of tyloxapol intravenously at 120 mg/kg of body weight to block hydrolysis of triacylglycerols in very low density lipoprotein (VLDL). Blood was sampled sequentially for 720 min and analyzed for concentration of triacylglycerol and total cholesterol. Lymph was sampled 6 h after tyloxapol infusion, and analyzed for concentrations of fatty acids, ß-hydroxybutyrate, glucose, triacylglycerol, and total cholesterol. A sample of serum collected at 720 min after tyloxapol was assayed for the metabolome composition. The area under the curve (AUC) of serum triacylglycerol, VLDL cholesterol, and total cholesterol were calculated. Orthogonal contrasts evaluated the effect of supplementing RPC (CON vs. [1/2 L25.8 + 1/2 H25.8]) and source of RPC (L25.8 vs. H25.8). Least squares means and standard errors of the means are presented in sequence as CON, L25.8, H25.8. During feed restriction, supplementation of RPC reduced hepatic triacylglycerol (9.0 vs. 4.1 vs. 4.5 ± 0.6%) and increased glycogen contents (1.9 vs. 3.5 vs. 4.1 ± 0.2%). Similarly, supplementation of RPC increased the expression of transcripts involved in the synthesis and assembly of lipoproteins (MTTP), cellular autophagy (ATG3), and inflammation (TNFA), and reduced the expression of transcripts associated with mitochondrial oxidation of fatty acids (HADHA, MLYCD) and stabilization of lipid droplets (PLIN2). After infusion of tyloxapol, RPC increased the AUC for serum triacylglycerol (21,741 vs. 32,323 vs. 28,699 ± 3,706 mg/dL × min) and VLDL cholesterol (4,348 vs. 6,465 vs. 5,740 ± 741 mg/dL × min) but tended to reduce the concentrations of triacylglycerol in lymph (16.7 vs. 13.8 vs. 11.9 ± 1.9 mg/dL). Feeding RPC tended to increase the concentrations of 89 metabolites in serum, after adjusting for false discovery, including 3 acylcarnitines, 1 AA-related metabolite, 11 bile acids, 1 ceramide, 6 diacylglycerols, 2 dihydroceramides, 1 glycerophospholipid, and 64 triacylglycerols compared with CON. Feeding 25.8 g/d of choline ion as RPC mediated increased hepatic triacylglycerol secretion to promote lipotropic effects that reduced hepatic lipidosis in dairy cows.

Effect of source and amount of rumen-protected choline on hepatic metabolism during induction of fatty liver in dairy cows.

Objectives were to determine the effect of supplementing increased amounts of rumen-protected choline (RPC) from sources with low (L, 28.8%) or high (H, 60.0%) concentration of choline chloride on hepatic metabolism when cows were subjected to feed restriction to develop fatty liver. It was hypothesized that increased supplementation of RPC reduces hepatic triacylglycerol and enhances glycogen concentrations. Pregnant, nonlactating multiparous Holstein cows (n = 110) at mean (± standard deviation) 232 ± 3.9 d of gestation were blocked by body condition (4.01 ± 0.52) and assigned to receive 0 (CON), 12.9 (L12.9 or H12.9), or 25.8 (L25.8 or H25.8) g/d of choline ion. Cows were fed for ad libitum intake on d 1 to 5 and restricted to 50% of the NEL required for maintenance and pregnancy from d 6 to 13. Intake of metabolizable methionine was maintained at 19 g/d during the feed restriction period by supplying rumen-protected methionine. Hepatic tissue was sampled on d 6 and 13 and analyzed for triacylglycerol, glycogen, and mRNA expression of genes involved in choline, glucose, and fatty acids metabolism, cell signaling, inflammation, autophagy, lipid droplet dynamics, lipophagy, and endoplasmic reticulum stress response. Blood was sampled and analyzed for concentrations of fatty acids, ß-hydroxybutyrate (BHB), glucose, triacylglycerol, total cholesterol, and haptoglobin. Orthogonal contrasts evaluated the effect of supplementing RPC [CON vs. (1/4·L12.9 + 1/4·L25.8 + 1/4·H12.9 + 1/4·H25.8)], source of RPC [(1/2·L12.9 + 1/2·L25.8) vs. (1/2·H12.9 + 1/2·H25.8)], amount of RPC [(1/2·L12.9 + 1/2·H12.9) vs. (1/2·L25.8 + 1/2·H25.8)], and interaction between source and amount [(1/2·L12.9 + 1/2·H25.8) vs. (1/2·H12.9 + 1/2·L25.8)]. Least squares means and standard error of the means are presented in sequence as CON, L12.9, L25.8, H12.9, H25.8. Supplementation of RPC reduced hepatic triacylglycerol (9.3 vs. 6.6 vs. 5.1 vs. 6.6 vs. 6.0 ± 0.6% as-is) and increased glycogen contents (1.8 vs. 2.6 vs. 3.6 vs. 3.1 vs. 4.1 ± 0.2% as-is) on d 13 of the experiment. Feeding RPC reduced serum haptoglobin (136.6 vs. 85.6 vs. 80.6 vs. 82.8 vs. 81.2 ± 4.6 µg/mL) during the feed restriction period; however, blood concentrations of fatty acids, BHB, glucose, triacylglycerol, and total cholesterol did not differ among treatments. During feed restriction, supplementation of RPC enhanced the mRNA expression of genes related to choline metabolism (BHMT), uptake of fatty acids (CD36), and autophagy (ATG3), and reduced the expression of a transcript associated with endoplasmic reticulum stress response (ERN1). An increase in the amount of choline ion from 12.9 to 25.8 g/d enhanced the mRNA expression of genes associated with synthesis and assembly of lipoproteins (APOB100), and inflammation (TNFA), whereas it reduced the expression of genes linked to gluconeogenesis (PC), oxidation of fatty acids (ACADM, MMUT), ketogenesis (ACAT1), and synthesis of antioxidants (SOD1) on d 13 of the experiment. Feeding RPC, independent of the product used, promoted lipotropic effects that reduced hepatic lipidosis in dairy cows.

Induced endometritis in early lactation compromises production and reproduction in dairy cows.

Objectives of this experiment were to study the effect of infusing utero-pathogenic bacteria to induce endometrial inflammation on productive performance in early lactation and subsequent reproduction. Although endometritis is associated with perturbed reproduction, numerous factors may contribute to the observed association. It was hypothesized that induced endometrial inflammation, resulting in localized and systemic inflammatory responses, compromises production and reproduction. Holstein cows without clinical disease and with less than 18% polymorphonuclear leukocytes (PMN) in endometrial cytology on d 31 ± 3 postpartum had their estrous cycle synchronized. Cows were blocked by parity and genomic breeding value for cow conception rate and, within block, assigned randomly to remain as untreated controls (CON; n = 37) or to receive an intrauterine infusion of 5.19 × 108 cfu Escherichia coli and 4.34 × 108 cfu Trueperella pyogenes during the luteal phase to induce endometrial inflammation (INF; n = 48). Endometrial cytology was taken on d 2 and 7 after treatment to evaluate the proportion of PMN. Rectal temperature, dry matter intake, and yields of milk and components were measured in the first 7 d after treatment. Blood serum was analyzed for concentration of haptoglobin. Leukocytes were isolated from blood on d 2 and 7 after treatment and on d 19 after artificial insemination (AI) and mRNA was quantified for a select group of genes. Cows received AI and reproduction was followed for 300 d postpartum. Bacterial infusion induced endometrial inflammation with increased proportions of PMN in the endometrial cytology on d 2 (4.4 ± 0.7 vs. 26.3 ± 2.8%) and 7 (10.9 ± 1.7 vs. 17.4 ± 2.1%) after treatment, resulting in increased mean prevalence of subclinical endometritis (>10% PMN; 23.3 ± 6.3 vs. 80.9 ± 5.1%). Rectal temperature did not differ between CON and INF, but the concentration of haptoglobin in serum tended to increase in INF compared with CON (113 ± 14 vs. 150 ± 16 µg/mL). Induced endometrial inflammation reduced yields of milk (44.9 ± 0.8 vs. 41.6 ± 0.8 kg/d), protein (1.19 ± 0.03 vs. 1.12 ± 0.03 kg/d), and lactose (2.17 ± 0.04 vs. 2.03 ± 0.04 kg/d) and tended to reduce dry matter intake (20.7 ± 0.5 vs. 19.4 ± 0.6 kg/d) in the first 7 d after treatment. Indeed, the reduction in milk yield lasted 4 wk. However, treatment did not affect yields of energy-corrected milk or fat because treatment with INF increased the concentration of fat in milk (3.54 ± 0.10 vs. 3.84 ± 0.10%). Induced endometrial inflammation reduced pregnancy per AI at all inseminations (33.4 ± 5.1 vs. 21.6 ± 3.7%) and the hazard of pregnancy (0.61; 95% CI = 0.36-1.04), which extended the median days open by 24 d. Blood leukocytes from INF cows had increased mRNA expression of the pro-inflammatory gene IL1B on d 2 and 7 after treatment, but reduced expression of the IFN-stimulated genes ISG15 and MX2 on d 19 after AI. Induced endometrial inflammation depressed production and caused long-term negative effects on reproduction in lactating dairy cows.

Effect of source and amount of vitamin D on serum concentrations and retention of calcium, magnesium, and phosphorus in dairy cows.

The objectives of the experiment were to determine the effects of supplementing 2 amounts of 25-hydroxyvitamin D3 (calcidiol; CAL) compared with equal amounts of vitamin D3 (cholecalciferol; CHOL) on serum concentrations, absorptions, and retentions of Ca, Mg, and P in periparturient dairy cows. One hundred seventy-seven (133 parous and 44 nulliparous) pregnant Holstein cows were enrolled in the experiment. Cows were blocked by parity and previous lactation milk yield (parous) or genetic merit for energy-corrected milk yield (nulliparous) and assigned randomly to receive 1 or 3 mg/d of CAL or CHOL in a 2 × 2 factorial arrangement of treatments. Treatments were provided to individual cows as a top-dress to the prepartum diet from 250 d gestation until parturition. The prepartum diet had a dietary cation-anion difference of -128 mEq/kg of dry matter. All cows were fed a common postpartum diet containing 46 µg of vitamin D3/kg of dry matter without further supplementation of treatments. Concentrations of vitamin D metabolites, Ca, Mg, and P in serum were measured pre- and postpartum, in addition to total-tract digestibility and urinary excretion of Ca, Mg, and P in the prepartum period. Feeding 3 mg compared with 1 mg of CAL increased serum 25-hydroxyvitamin D3 (CAL1 = 94 vs. CAL3 = 173 ± 3 ng/mL). In comparison, the increment in serum 25-hydroxyvitamin D3 from feeding 3 mg compared with 1 mg of CHOL was small (CHOL1 = 58 vs. CHOL3 = 64 ± 3 ng/mL). Feeding CAL increased prepartum concentration of P in serum compared with CHOL (CHOL = 1.87 vs. CAL = 2.01 ± 0.02 mM), regardless of the amount fed, but neither source nor amount affected prepartum Ca or Mg in serum. Feeding CAL increased serum Ca and P for the first 11 d postpartum compared with CHOL (CHOL = 2.12 vs. CAL = 2.16 ± 0.01 mM serum Ca; CHOL = 1.70 vs. CAL = 1.78 ± 0.02 mM serum P) but the amount of vitamin D did not affect postpartum concentrations of Ca, Mg, and P in serum. Feeding CAL increased prepartum apparent digestibility of Ca compared with CHOL (CHOL = 26.6 vs. CAL = 33.5 ± 2.8%) but treatments did not affect Ca retention prepartum. Neither source nor amount of vitamin D affected Mg and P apparent digestibility, but CAL decreased the concentration of P excreted in urine during the prepartum period (CHOL = 1.8 vs. CAL = 0.8 ± 0.3 g/d). Calcidiol tended to increase the amount of Ca secreted in colostrum (CHOL = 9.1 vs. CAL = 11.2 ± 0.9 g/d) and Ca excreted in urine postpartum (CHOL = 0.4 vs. CAL = 0.6 ± 0.1 g/d) compared with CHOL. Collectively, feeding CAL at 1 or 3 mg/d compared with CHOL in the last 24 d of gestation is an effective way to increase periparturient serum P concentration and postpartum serum Ca of dairy cows fed a prepartum diet with negative DCAD.

Effect of prepartum source and amount of vitamin D supplementation on lactation performance of dairy cows.

The objectives of this experiment were to determine the effects of supplementing 25-hydroxyvitamin D3 (calcidiol, CAL) compared with vitamin D3 (cholecalciferol, CHOL) at 1 or 3 mg/d in late gestation on production outcomes of dairy cows. One hundred thirty-three parous and 44 nulliparous pregnant Holstein cows were enrolled in the experiment. Cows were blocked by parity and previous lactation milk yield (parous) or genetic merit (nulliparous) and assigned randomly to receive 1 or 3 mg/d of CAL or CHOL in a 2 × 2 factorial arrangement of treatments (CAL1, CAL3, CHOL1, and CHOL3). Treatments were provided to individual cows as a top-dress to the prepartum diet from 250 d in gestation until parturition. The prepartum diet had a dietary cation-anion difference of -128 mEq/kg of dry matter. Production and disease were evaluated for the first 42 d in milk, and reproduction was evaluated to 300 d in milk. Incidence of postpartum diseases did not differ among treatments. Feeding CAL compared with CHOL increased yields of colostrum and colostrum fat, protein, and total solids, resulting in an increased amount of net energy for lactation secreted as colostrum (CHOL = 7.0 vs. CAL = 9.0 ± 0.7 Mcal). An interaction between source and amount was observed for milk yield: CAL3 increased milk yield compared with CHOL3 (CHOL3 = 34.1 vs. CAL3 = 38.7 ± 1.4 kg/d) but milk yield did not differ between CAL1 and CHOL1 (CHOL1 = 36.9 vs. CAL1 = 36.4 ± 1.4 kg/d). Concentrations of serum calcidiol on day of calving and average serum Ca from d 2 to 11 postpartum were positively associated with milk yield in the first 42 d in milk. Interactions between source and amount of vitamin D were also observed for pregnancy after first AI: the percentage of cows receiving CHOL1 and CAL3 that became pregnant was smaller than that of cows receiving CHOL3 and CAL1. However, pregnancy per AI and pregnancy by 300 d in milk did not differ among treatments. Overall, CAL3 increased milk yield compared with CHOL3, whereas in cows fed 1 mg/d (CAL1 and CHOL1), the source of vitamin D generally had no effect. The effect of CAL3 may be explained in part by serum CAL concentrations and postpartum serum Ca, which were associated with milk yield.

Prepartum level of dietary cation-anion difference fed to nulliparous cows: Acid-base balance, mineral metabolism, and health responses.

Objectives were to determine the effects of 3 different levels of dietary cation-anion difference (DCAD) fed during the last 22 d of gestation to pregnant nulliparous cows on pre- and postpartum acid-base balance, mineral metabolism, and health responses. In all, 132 pregnant nulliparous Holstein cows were enrolled at 250 (248-253) d of gestation, blocked by genomic merit of energy-corrected milk yield, and assigned randomly to diets varying in DCAD: +200 (P200, n = 43), -50 (N50, n = 45), or -150 (N150, n = 44) mEq/kg of dry matter. Dietary treatments were fed until calving, after which cows received the same lactation diet for the first 100 d postpartum. Urine and blood were sampled throughout the prepartum period and in the first weeks postpartum, and urine was assessed for pH, whereas blood was analyzed for gases, measures of acid-base balance, minerals, and metabolites. Calcium (Ca) and magnesium (Mg) retention and phosphorus (P) digestibility were evaluated in the last week of gestation and first week of lactation. Incidence of diseases was evaluated for the first 100 d postpartum. Data are presented in sequence as P200, N50, N150 (LSM ± SEM). Reducing the DCAD reduced urine (8.17 vs. 6.50 vs. 5.51 ± 0.11) and blood pH (7.442 vs. 7.431 vs. 7.410 ± 0.004) and induced a state of compensated metabolic acidosis with a reduction in blood HCO3- (28.4 vs. 26.7 vs. 24.9 ± 0.3 mM) and partial pressure of CO2 (41.8 vs. 40.1 vs. 39.1 ± 0.4 mmHg) prepartum. Reducing the DCAD linearly increased blood ionized Ca (iCa; 1.224 vs. 1.243 vs. 1.259 ± 0.008 mM) and serum total Ca (tCa; 2.50 vs. 2.53 vs. 2.56 ± 0.02 mM) prepartum, blood iCa on the day of calving, and serum Mg in the first days postpartum. Reducing the DCAD linearly increased the apparent absorption of Ca (12.9 vs. 19.0 vs. 20.9 ± 1.4 g/d) and Mg (7.0 vs. 9.9 vs. 10.4 ± 1.4 g/d) prepartum, but apparent retention of both Ca (13.9 g/d) and Mg (3.4 g/d) did not differ with treatment. Treatment did not affect digestibility of P pre- or postpartum or retention of Ca or Mg postpartum. Treatment did not affect the incidence or prevalence of subclinical hypocalcemia, hepatic composition, or the prevalence of fatty liver. Reducing the DCAD had a quadratic effect on incidence of fever (46.5 vs. 17.6 vs. 33.9 ± 7.0%), uterine diseases (36.3 vs. 25.6 vs. 46.0 ± 7.3%), and morbidity (41.4 vs. 28.1 vs. 55.6 ± 7.3%). Feeding a diet with -50 mEq/kg of dry matter promoted moderate changes in acid-base balance, altered mineral metabolism, and benefited health of nulliparous cows; however, further reducing the DCAD to -150 mEq/kg negated the benefits to health.

Effect of source and amount of vitamin D on function and mRNA expression in immune cells in dairy cows.

Objectives were to determine the effect of supplementing 2 sources of vitamin D, cholecalciferol (CH) or calcidiol (CA), at 1 (1mg) or 3 mg/d (3mg) prepartum on concentrations of vitamin D metabolites in plasma, measures of innate immune function, and leukocyte mRNA expression. Parous Holstein cows (n = 99) were assigned to a daily treatment administered as top-dress containing either 1 or 3 mg of CH (CH1 or CH3) or of CA (CA1 or CA3) from 250 d of gestation until calving. Plasma concentrations of vitamin D, immune cell population in blood, cell adhesion markers, and granulocyte phagocytosis and oxidative burst were evaluated pre- and postpartum. The mRNA expression in leukocytes was determined at 270 d of gestation and 3 d postpartum for genes involved in cell migration, pathogen recognition receptors, cell signaling, cytokines, antimicrobial mechanisms, oxidative burst, and Ca and vitamin D metabolism. Concentrations of vitamin D3 increased in cows fed CH, whereas those of 25-hydroxyvitamin D3 increased in cows fed CA. Percentage of granulocytes from total leukocytes differed with amount of vitamin D pre- (1mg = 24.5 vs. 3mg = 37.9%) and postpartum (1mg = 22.0 vs. 3mg = 31.0%), thus shifting mononuclear cells in the opposite direction pre- (1mg = 75.5 vs. 3mg = 62.1%) and postpartum (1mg = 78.0 vs. 3mg = 69.0%). Granulocytes displaying phagocytosis (1mg = 69.0 vs. 3mg = 62.9%) and intensity of phagocytosis prepartum (1mg = 7.46 vs. 3mg = 7.28) tended to be less in cows fed 3mg compared with 1mg. During prepartum, CA increased mRNA expression of genes related to cell adhesion and migration (CD44, ICAM1, ITGAL, ITGB1, LGALS8, SELL), pathogen recognition receptor (NOD2, TLR2, TLR6), cell signaling (FOS, JUN, NFKB2), cytokine signaling (IL1B, IL1R1, IL1RN), antimicrobial mechanisms (CTSB, LYZ), and Ca metabolism (ATP2B1, STIM1, TRPV5) compared with CH. Similarly, postpartum, CA increased mRNA expression of genes related to cell adhesion and migration (CXCR2, SELL, TLN1), cell signaling (AKT2), cytokines (CCL2, IL1R1, ILRN), antimicrobial mechanisms (DEFB3), oxidative burst (RAC2), and calcium metabolism (CALM3) compared with CH. Feeding additional vitamin D in the last 3 wk of gestation changed the profile of blood leukocytes and attenuated granulocyte phagocytosis during the transition period, whereas supplementing CA prepartum increased mRNA expression of genes involved in immune cell function, including genes related to pathogen recognition and antimicrobial effects of leukocytes.

Prepartum level of dietary cation-anion difference fed to nulliparous cows: Lactation and reproductive responses.

Objectives were to determine the effects of 3 levels of dietary cation-anion difference (DCAD) fed prepartum to nulliparous cows on productive and reproductive performance. We enrolled 132 pregnant nulliparous Holstein cows at 250 (248-253) d of gestation in a randomized block design. Cows were blocked by genomic merit of energy-corrected milk yield and assigned randomly to diets varying in DCAD, +200 (P200; n = 43), -50 (N50; n = 45), or -150 (N150; n = 44) mEq/kg of dry matter (DM). Dietary treatments were fed during the last 22 d of gestation and, after calving, postpartum cows received the same lactation diet. Productive performance was evaluated for the first 14 wk of lactation, and reproduction was assessed until 305 d postpartum. Intake of DM prepartum decreased linearly (results presented in sequence as least squares means ± standard error of the mean, P200 vs. N50 vs. N150) with a reduction in DCAD (9.0 vs. 8.9 vs. 8.4 ± 0.1 kg/d), which resulted in linear decreases in net energy balance (0.34 vs. 0.20 vs. -0.36 ± 0.20 Mcal/d), body weight change (1.1 vs. 0.8 vs. 0.3 ± 0.1 kg/d), and mean body weight (652 vs. 649 vs. 643 ± 2 kg) prepartum. Treatment did not affect yield of colostrum (6.3 vs. 5.8 vs. 5.1 ± 0.6 kg) or the contents or yields of fat, protein, lactose, IgG, Ca, or Mg in colostrum. Intake of DM (19.4 vs. 19.2 vs. 19.0 ± 0.2 kg/d), yields of milk (36.6 vs. 36.7 vs. 35.8 ± 0.6 kg/d) or energy-corrected milk (36.7 vs. 36.3 vs. 35.9 ± 0.5 kg/d), feed efficiency (1.93 vs. 1.92 vs. 1.93 ± 0.03 kg of energy-corrected milk per kilogram of DM intake), and content and yield of milk components did not differ among treatments during the first 14 wk of lactation. Prepartum DCAD did not affect the cumulative milk yield by 305 d of lactation (9,653 vs. 10,005 vs. 9,918 ± 196 kg). Of the 132 cows, 40 P200, 45 N50, and 43 N150 received at least 1 artificial insemination (AI), and treatment did not affect pregnancy per AI at first (32.5 vs. 35.6 vs. 37.2%) or all AI (30.6 vs. 33.9 vs. 40.2%), although reducing the DCAD increased the proportion of cows pregnant by 305 d postpartum (76.7 vs. 88.9 vs. 93.2%) without altering the rate of pregnancy. Collectively, manipulating the DCAD of prepartum diets, from +200 to -150 mEq/kg of DM, fed to late gestation nulliparous cows did not affect subsequent lactation productive performance, but may have provided some benefit to reproduction, which warrants further confirmation.

Reversal of ß-Amyloid-Induced Microglial Toxicity In Vitro by Activation of Fpr2/3.

Microglial inflammatory activity is thought to be a major contributor to the pathology of neurodegenerative conditions such as Alzheimer's disease (AD), and strategies to restrain their behaviour are under active investigation. Classically, anti-inflammatory approaches are aimed at suppressing proinflammatory mediator production, but exploitation of inflammatory resolution, the endogenous process whereby an inflammatory reaction is terminated, has not been fully investigated as a therapeutic approach in AD. In this study, we sought to provide proof-of-principle that the major proresolving actor, formyl peptide receptor 2, Fpr2, could be targeted to reverse microglial activation induced by the AD-associated proinflammatory stimulus, oligomeric ß-amyloid (oAß). The immortalised murine microglial cell line BV2 was employed as a model system to investigate the proresolving effects of the Fpr2 ligand QC1 upon oAß-induced inflammatory, oxidative, and metabolic behaviour. Cytotoxic behaviour of BV2 cells was assessed through the use of cocultures with retinoic acid-differentiated human SH-SY5Y cells. Stimulation of BV2 cells with oAß at 100 nM did not induce classical inflammatory marker production but did stimulate production of reactive oxygen species (ROS), an effect that could be reversed by subsequent treatment with the Fpr2 ligand QC1. Further investigation revealed that oAß-induced ROS production was associated with NADPH oxidase activation and a shift in BV2 cell metabolic phenotype, activating the pentose phosphate pathway and NADPH production, changes that were again reversed by QC1 treatment. Microglial oAß-stimulated ROS production was sufficient to induce apoptosis of bystander SH-SY5Y cells, an effect that could be prevented by QC1 treatment. In this study, we provide proof-of-concept data that indicate exploitation of the proresolving receptor Fpr2 can reverse damaging oAß-induced microglial activation. Future strategies that are aimed at restraining neuroinflammation in conditions such as AD should examine proresolving actors as a mechanism to harness the brain's endogenous healing pathways and limit neuroinflammatory damage.

Meta-analysis of the effects of prepartum dietary protein on performance of dairy cows.

The objectives were to review the published literature and use meta-analytic methods to determine the effects of dietary protein fed prepartum on productive performance of dairy cows. The hypothesis was that responses to dietary protein prepartum would differ between nulliparous and parous cows, and performance would be maximized at a greater protein supply in nulliparous than in parous cows. The literature was systematically reviewed, searching randomized experiments in which the prepartum dietary content or degradability of protein was manipulated. Twenty-seven experiments including 125 treatment means and 1,801 cows were included in the meta-analysis. Of those, 8 experiments with 27 treatment means reported responses for 510 nulliparous cows. Data collected included the ingredient composition and chemical analyses of prepartum diets, parity group, and means and respective measures of variance for productive responses. Mixed model meta-analysis was conducted and statistical models investigated the effects of dietary crude protein (CP) or supply of metabolizable protein (MP) prepartum on performance. Supply of MP was predicted using the National Research Council Nutrient Requirements of Dairy Cattle (2001) model. The mean ± standard deviation and median (range) concentrations of dietary CP fed to cows prepartum were 14.4 ± 2.2 and 14.4% (8.9 to 20.9%), resulting in mean and median (range) intakes of CP prepartum of 1,720 ± 432 and 1,734 g/d (745 to 2,482 g/d). Predicted prepartum supply of MP averaged 822 ± 157 in nulliparous cows, ranging from 517 to 1,094 g/d, and 1,146 ± 316 in parous cows, ranging from 463 to 1,733 g/d. Increasing prepartum CP content or predicted supply of MP improved postpartum dry matter intake in nulliparous cows, but increasing prepartum CP content reduced prepartum dry matter intake in parous cows. Yields of milk and fat-corrected milk increased with increasing prepartum supply of MP in nulliparous but not in parous cows. Yields of fat and protein increased in nulliparous cows with increased CP content or supply of MP. Alternatively, in parous cows, yield of milk fat was not influenced by supply of MP but responded quadratically to dietary CP content and was maximized at approximately 14% CP. Dietary CP had no effect on protein yield in parous cows, but increasing the supply of MP improved protein yield only in cows from experiments with >36 kg/d of milk production, whereas MP supply had no effect on protein yield of parous cows from experiments with <28 kg/d of milk production. Performance of dairy cows was responsive to prepartum supply of MP and nulliparous benefited from diets with increased MP intake. Based on current results, production responses for nulliparous cows increased linearly up to the maximum MP intake of 1,100 g/d observed in the study, whereas for parous cows, only yield of milk protein in cows producing more than 36 kg of milk/d was influenced by supplying more than 800 g/d of MP.

Effect of timing of insemination after CIDR removal with or without GnRH on pregnancy rates in Nili-Ravi buffalo.

There are limited studies available on when to inseminate, if using CIDR or CIDR-GnRH protocols for optimal fertility in buffalo. Therefore, the objective of the present study was to determine the optimum time of AI in relation to CIDR removal with or without GnRH in buffalo. All buffalo (n=201) received CIDR on Day 0, PGF2α on Day 6 and CIDR were removed on Day 7. In 50 of these buffalo GnRH was administered 36 h after CIDR removal. Furthermore, CIDR (n=151) and CIDR-GnRH (n=50) were randomly divided to receive timed artificial insemination (TAI), either at 48, 60 or 72 h after CIDR removal. Ultrasonography was performed for follicular development and for pregnancy diagnosis. The results revealed that, mean interval to ovulation was shorter (P<0.05) in buffalo receiving CIDR-GnRH than CIDR (68.40 ± 1.73 compared with 76.13 ± 1.66 h, respectively). The pregnancy rates were higher (P<0.05) in buffalo inseminated either at 48 (50%) or 60 (59%) than at 72 h (18%) in CIDR-GnRH protocol; whereas, in CIDR buffalo pregnancy rates were higher (P<0.05), at 60 (37%) or 72 (40%) than at 48 h (10%). In conclusion, the optimal time of AI is between 48-60 h in CIDR-GnRH and between 60-72 h in CIDR protocol for enhancing fertility in buffalo.