Immediate effects of transcutaneous electrical nerve stimulation on gait patterns in chronic stroke survivors: A single group, pretest-posttest clinical trial.

BACKGROUND: Transcutaneous electrical nerve stimulation (TENS) has been used to reduce muscle spasticity and improve locomotion in stroke survivors. We speculate that acute changes in gait performance after TENS mediate functional improvement in the long-term. However, no previous study has investigated the effect of TENS on ankle kinetics and kinematics during walking in stroke survivors. PURPOSE: We aimed to investigate whether TENS applied over the paretic leg could rapidly improve the plantar flexion moment and ankle kinematics in chronic stroke survivors with lower limb paresis. METHODS: Twenty chronic stroke survivors were recruited. They underwent 30 min of TENS over the area innervated by the common peroneal nerve on the paretic leg. Three-dimensional (3D) motion capture was performed and ankle plantar flexor spasticity was assessed before and immediately after stimulation. Ankle kinematics and kinetic and spatiotemporal data were collected using 3D motion capture. Ankle plantar flexor spasticity was assessed using the Modified Tardieu Scale. PRINCIPAL RESULTS: A significant increase in the ankle plantar flexion moment of the paretic side during the pre-swing phase was observed immediately after stimulation (p = 0.009, maximal mean difference = 0.035, 95%CI = 0.0125 to 0.0575). The step length of the paretic limb also increased significantly after stimulation (p = 0.023, mean difference = -0.02, 95%CI = -0.04 to -0.004). TENS had no immediate effect on paretic ankle spasticity, as measured by the Modified Tardieu Scale, or on other temporo-spatial parameters. CONCLUSION: The findings support the use of TENS to improve the motor function and gait pattern in chronic stroke survivors. The study indicated that the application of TENS to the paretic leg before gait training might improve rehabilitation outcomes. Future studies investigating the effects of TENS on functional outcomes, the optimal stimulation duration, and assessing spasticity using more sensitive measures are warranted.

Effect of fish oil and canola oil supplementation on immunological parameters, feed intake, and growth of Holstein calves.

Supplemental n-3 fatty acids (FA) may support better immune responses than n-6 and n-9 FA in dairy calves. The objective was to evaluate the effect of n-3 FA, supplemented as a fish oil product (FO) in the milk replacer (MR), in comparison to n-6 and n-9 FA, supplemented as canola oil (CO), on body weight (BW), daily gain, and immunological parameters of preweaning Holstein calves. The study was conducted from September to December 2019. Calves were randomly allocated to a control group (n = 15; BW = 36.2 ± 1.5 kg; mean ± SEM) supplemented daily with 30 mL of CO and to an experimental group (n = 15; BW = 36.3 ± 1.5 kg) supplemented with 60 g of a product containing 30 g of FO. Both treatments were added to the MR during the morning feeding. All calves were fed 4 L of MR at 12.5% solids at 0700 and 1600 h for wk 1, 6 L from wk 2 to 7, and 3 L once daily (0700 h) during wk 8 until weaning (56 d). Blood samples were collected at 7, 14, 21, 28, 35, 42, 49, and 56 d of age for serum haptoglobin, TNF-α, IL-1ß, and protectin. Dry matter intake was recorded in all experimental calves daily. Seroneutralization titers to vaccination against viral diseases (infectious bovine rhinotracheitis, parainfluenza 3, bovine viral diarrhea, and bovine respiratory syncytial virus) were determined. Mixed models for repeated measures were developed to analyze variables over time. Seroneutralization titers were analyzed by the Kruskal-Wallis test. The other variables were compared by a generalized linear model. Serum FA profile at 35 d of age showed that FO supported higher concentrations of n-3 FA than CO. Final BW [65.2 vs. 62.0 kg, standard error of the mean (SEM) = 2.1 kg] and average daily gain (0.52 vs. 0.46 kg/d, SEM = 0.1 kg/d) tended to be higher for the FO than the CO group. An interaction of treatment × day for dry matter intake was observed, especially during weaning (2.17 kg vs. 1.94 kg, SEM = 0.158 kg, for FO and CO group, respectively). Blood lactate (mmol/L) was higher in the CO than in the FO group at d 7. Haptoglobin and IL-1ß were higher for the CO group on d 14 than the FO group. The TNF- α concentrations for the FO group were reduced over time, whereas the concentrations in the CO group remained constant. Protectin was higher in the FO group on d 14, but was lower on d 28, 35, and 49. Seroneutralization antibody titers postvaccination for the PI3 virus were higher for the FO than the CO group. In conclusion, calves supplemented with FO had lower concentrations of blood lactate, haptoglobin, IL-1ß and TNF-α than calves supplemented with CO during the study period. The FO supplementation had a higher DMI than CO supplementation. Results of this trial should be interpreted with caution due to the lack of a negative control group as well as the lower birth weight and growth rate observed under heat stress conditions.

Effects of evaporative cooling and dietary zinc source on heat shock responses and mammary gland development in lactating dairy cows during summer.

The objective of this study was to examine the effects of evaporative cooling and dietary supplemental Zn source on heat shock responses and mammary gland development of lactating dairy cows during summer. Seventy-two multiparous lactating Holstein cows were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement. Cows were either cooled (CL) or not cooled (NC) and fed diets supplemented with 75 mg of Zn/kg of dry matter (DM) from Zn hydroxychloride (IOZ) or 35 mg of Zn/kg of DM from Zn hydroxychloride plus 40 mg of Zn/kg of DM from Zn-Met complex (ZMC). The 168-d trial included a 12-wk baseline phase when all cows were cooled and fed respective dietary treatments, and a subsequent 12-wk environmental challenge phase when NC cows were deprived of evaporative cooling. Plasma was collected from a subset of cows (n = 24) at 1, 3, 5, 12, 26, 41, 54, 68, 81 d of the environmental challenge to measure heat shock protein (HSP) 70 concentration. Mammary biopsies were collected from another subset of cows (n = 30) at enrollment (baseline samples) and at d 7 and 56 of the environmental challenge to analyze gene expression related to heat shock response, apoptosis and anti-oxidative enzymes, and to examine apoptosis and cell proliferation using immunohistochemistry. Supplemental Zn source did not affect milk yield but NC cows produced less milk than CL cows. Supplemental Zn source had no effect on mammary gene expression of HSP27, 70, and 90 or plasma concentrations of HSP70. The NC cows had greater mammary gene expression of HSP than CL cows. Circulating HSP70 of NC cows gradually increased and was higher at 81 d of environmental challenge compared with CL cows. Relative to IOZ, ZMC cows tended to have lower total mammary cell proliferation but greater mammary apoptosis. There was a tendency of greater TNFRSF1A mRNA expression for ZMC compared with IOZ cows, which may suggest upregulated extrinsic apoptosis. At d 7 of environmental challenge, NC cows had numerically higher mammary apoptosis than CL cows although not statistically significant. The NC cows tended to have greater mRNA expression of CAT and SOD3 regardless of time, and had greater mRNA expression of GPX1 at d 56 and FAS at d 7 of the environmental challenge than CL cows. Relative to CL cows, mammary cell proliferation rate was higher for NC cows at d 56 of the environmental challenge. In conclusion, dietary source of supplemental Zn has substantial effect on mammary cell turnover in lactating dairy cows, and prolonged exposure to heat stress increases mammary cell proliferation.

Symposium review: One-carbon metabolism and methyl donor nutrition in the dairy cow.

The present review focuses on methyl donor metabolism and nutrition in the periparturient and lactating dairy cow. Methyl donors are involved in one-carbon metabolism, which includes the folate and Met cycles. These cycles work in unison to support lipid, nucleotide, and protein synthesis, as well as methylation reactions and the maintenance of redox status. A key feature of one-carbon metabolism is the multi-step conversion of tetrahydrofolate to 5-methyltetrahyrofolate. Homocysteine and 5-methyltetrahyrofolate are utilized by vitamin B12-dependent Met synthase to couple the folate and Met cycles and generate Met. Methionine may also be remethylated from choline-derived betaine under the action of betaine hydroxymethyltransferase. Regardless, Met is converted within the Met cycle to S-adenosylmethionine, which is universally utilized in methyl-group transfer reactions including the synthesis of phosphatidylcholine. Homocysteine may also enter the transsulfuration pathway to generate glutathione or taurine for scavenging of reactive oxygen metabolites. In the transition cow, a high demand exists for compounds with a labile methyl group. Limited methyl group supply may contribute to inadequate hepatic phosphatidylcholine synthesis and hepatic triglyceride export, systemic oxidative stress, and compromised milk production. To minimize the perils associated with methyl donor deficiency, the peripartum cow relies on de novo methylneogenesis from tetrahydrofolate. In addition, dietary supplementation of rumen-protected folic acid, vitamin B12, Met, choline, and betaine are potential nutritional approaches to target one-carbon pools and improve methyl donor balance in transition cows. Such strategies have merit considering research demonstrating their ability to improve milk production efficiency, milk protein synthesis, hepatic health, and immune response. This review aims to summarize the current understanding of folic acid, vitamin B12, Met, choline, and betaine utilization in the dairy cow. Methyl donor co-supplementation, fatty acid feeding strategies that may optimize methyl donor supplementation efficacy, and potential epigenetic mechanisms are also considered.

Pre- and postnatal heat stress abatement affects dairy calf thermoregulation and performance.

Prenatal heat stress during late gestation exerts long-term effects on growth and productivity of the dairy calf. Further, direct exposure to heat stress during the preweaning period impairs calf thermoregulation and performance. We examined the effects of heat stress abatement during the prenatal period, postnatal period, or both on calf performance. We hypothesized that calves exposed to pre- and postnatal heat stress abatement would perform most optimally in terms of thermoregulation, growth, and health responses when compared with calves that are heat-stressed at any time in the pre- or postnatal periods. Holstein calves born to heat-stressed (HT) or cooled (CL) dams during late gestation (44 ± 5 d; prenatal HT or CL) were exposed to heat stress or cooling postnatally for 56 d (postnatal HT or CL), resulting in 4 treatments: HT-HT, HT-CL, CL-HT, and CL-CL; n = 12/treatment. Calves were administered 4 L of pooled colostrum and after 2 d of age allotted 10 L/d milk replacer and up to 3 kg/d concentrate in automatic feeder group pens (n = 6/pen). Postnatal cooling was achieved by 2 fans (average wind speed 2 m/s). Thermoregulatory responses (respiration rate and heart rate; rectal, body, and skin temperature), feed intake, growth parameters including average daily gain and medication events were recorded, and blood samples were collected weekly. Thermoregulatory responses were lower in postnatal CL calves compared with postnatal HT. In the afternoon, HT-HT calves had the highest respiration rate and rectal temperature, HT-CL calves had the lowest respiration rate, and CL-HT calves had the lowest heart rate compared with the other treatment groups. Prenatal CL calves weighed more at birth and weaning with a tendency for greater average daily gain compared with prenatal HT calves, whereas postnatal CL calves had increased milk replacer and concentrate intake and a tendency for reduced fever, infection, and total medication events relative to postnatal HT. Prenatal HT calves were esophageal tube fed more often than prenatal CL. Blood hematocrit and 24-h serum IgG concentration were greater in prenatal CL calves relative to prenatal HT. Prenatal heat stress abatement improves weight gain, hematocrit, and immunoglobulin transfer, whereas postnatal heat stress abatement modulates thermoregulatory responses, feed intake, and calf health. This study is the first to characterize the combined effects of pre- and postnatal heat stress or active cooling on the dairy calf.

Effects of acute and chronic heat stress on feed sorting behaviour of lactating dairy cows.

Nutritional strategies to mitigate the negative effects of heat stress on animal welfare and productivity often involve changes in ration formulation. However, cattle commonly sort their ration in favour of certain components, and it is not clear how feed sorting responds to heat stress. This study investigated the association between heat stress and feed sorting behaviour. Lactating Holstein dairy cows (n = 32; parity = 2.8±1.2; mean±SD) were housed in a free stall barn and milked 3×/day. Cows were fed individually using the Calan Broadbent Feeding System and offered ad libitum access to a total mixed ration (containing on a dry matter basis: 3.3% ryegrass hay, 16.5% ryegrass baleage, 24.7% corn silage, 11.1% brewers grains, 19.7% ground corn, 19.8% concentrate and 4.9% protein/mineral supplement), provided 1×/day. Beginning at 186±60 days in milk, cows were exposed to either: heat stress conditions (HT; n = 15) (average temperature-humidity index: 77.6), or evaporative cooling (CL; n = 17), consisting of misters and fans over the freestall and feed bunks. Data were collected during a 4-day baseline period, and two 4-day experimental periods: starting at 10 days after implementing treatments (defined as acute heat stress for HT cows), and at 62 days after implementing treatments (defined as chronic heat stress for HT cows). Daily feed intake and physiological responses to heat stress (body temperature, respiration rate) were recorded. Samples of fresh and refused feed were collected daily from individual cows for particle size analysis. The particle size separator had three screens (19, 8 and 1.18 mm) and a bottom pan, resulting in 4 fractions (long, medium, short and fine particles). Feed sorting was calculated as the actual intake of each particle size fraction expressed as a percentage of the predicted intake of that fraction. During both heat stress periods, HT cows sorted for long particles more than CL cows (105.0% v. 100.6%; SE = 1.1). During acute heat stress, HT cows sorted to a greater extent than CL cows against medium and short particles, whereas sorting of these fractions did not differ during chronic heat stress. Body temperature and respiration rate were associated across treatments with the extent of sorting for long particles and against short particles during acute heat stress. These results suggest that feed sorting is particularly influenced during acute heat stress, and that sorting for longer particles may increase in heat stress.

Effect of varying prepartum dietary cation-anion difference and calcium concentration on postpartum mineral and metabolite status and milk production of multiparous cows.

Eighty-two multiparous Holstein cows were enrolled 28 d before expected calving and assigned to 1 of 4 dietary treatments in a randomized block design experiment with a 2 × 2 factorial arrangement of treatments to determine the effect of feeding a neutral or acidogenic diet varying in Ca concentration on prepartum and postpartum intake, blood mineral and metabolite concentrations, and postpartum milk production. Prepartum diets were formulated to provide a dietary cation-anion difference (DCAD) of -21 (negative, NEG) or -2 (neutral, NEU) mEq/100 g of dry matter with either 1.3% or 1.8% Ca. After calving, cows remained on trial through 63 d in milk (DIM) and were fed a common lactation diet. Urine pH was lower for NEG compared with NEU and tended to be lower for 1.8% Ca compared with 1.3% Ca. Fractional excretion of Ca and Mg in urine was greater for NEG than for NEU. Prepartum plasma bicarbonate was lower and P was higher for NEG compared with NEU. Prepartum plasma P and blood urea nitrogen to creatinine ratio was higher for 1.3% compared with 1.8% Ca. Postpartum, concentrations of plasma total protein, albumin, blood urea nitrogen, Mg, and ionized Mg (iMg) were higher and Na was lower for NEU compared with NEG. An interaction of DCAD and Ca was observed for plasma creatinine, which was highest for cows fed NEU and 1.3% Ca compared with all other treatments. Interactions of DCAD and DIM were observed for plasma bicarbonate and iMg. Bicarbonate was higher at 3 DIM and lower at 14 DIM for NEU compared with NEG. Concentrations of iMg were higher at 1, 2, and 14 DIM for NEU compared with NEG. Interactions of Ca and DIM were observed for plasma Ca, Cl, and anion gap. Compared with cows fed 1.5% Ca, those fed 1.3% Ca had lower Ca and anion gap and higher Cl at 1 DIM and lower Cl and higher anion gap at 14 DIM. No differences were observed in body weight or body condition score due to DCAD or Ca. Prepartum dry matter intake (DMI) was lower for NEG compared with NEU and lower for 1.8% compared with 1.3% Ca. Postpartum DMI was not different among treatments. An interaction was observed for DCAD and DIM due to higher milk yield after 45 DIM for NEG compared with NEU. No differences were observed in milk component percentage or yield among treatments. There was an interaction of DIM and Ca for milk urea concentrations, which were higher at 5 wk and lower at 6 wk for 1.3% Ca compared with 1.8% Ca. These results suggest that feeding NEG prepartum alters plasma and urine mineral concentrations compared with feeding NEU and supports increased milk yield after 45 DIM. Feeding 1.8% Ca prepartum only improved plasma Ca at 1 DIM. Feeding either NEG or 1.8% Ca reduced DMI prepartum compared with NEU or 1.3% Ca.

Short communication: Blood mineral and gas concentrations of calves born to cows fed prepartum diets differing in dietary cation-anion difference and calcium concentration.

Eighty-two multiparous Holstein cows were fed diets differing in dietary cation-anion difference (DCAD) and Ca concentrations in a randomized block design experiment beginning 4 wk before anticipated calving to determine the effects on colostrum yield and quality and acid-base balance and mineral status of newborn calves. Treatments were arranged as a 2 × 2 factorial to provide 2 DCAD [-22 mEq/100 g of dry matter (NEG) or -3 mEq/100 g of dry matter (NEU)] and 2 supplemental Ca concentrations (1.3 or 1.8% of dry matter). After calving, cows were milked within 2 to 8 h and colostrum yield was recorded. Calves were fed 200 g of IgG of a commercial colostrum replacer within 4 h of birth. No differences were observed in birth weight or dystocia score among treatments, which averaged 42.7 kg and 1.12, respectively. Colostrum yield was not different among treatments and averaged 8.75 kg. Colostrum quality, as measured using a Brix refractometer, was not affected by DCAD but was higher for 1.3% compared with 1.8% Ca: 21.58% and 19.87%, respectively. Colostrum IgG concentrations were higher for NEG compared with NEU and for 1.3% compared with 1.8% Ca. No differences were observed in concentrations of serum IgG, Ca, P, K, Cl, anion gap, or whole-blood pH, partial pressure of O2, or SO2 of calves among treatments. Serum Mg and lactate concentrations were higher and CO2 tended to be lower for calves born to cows fed 1.3% compared with 1.8% Ca. Interactions of DCAD and Ca were observed for serum Na and Cl, which were higher for NEU-1.3% Ca and NEG-1.8% Ca compared with NEU-1.8% Ca and NEG-1.3% Ca. Whole-blood partial pressure of CO2, and HCO3 exhibited an interaction of DCAD and Ca and tended to be lower for NEU-1.3% Ca and NEG-1.8% Ca compared with NEU-1.8% Ca and NEG-1.3% Ca. Results of this trial indicate that feeding prepartum diets with 1.8% compared with 1.3% supplemental Ca reduced colostrum quality and serum concentrations of Mg and lactate in calves immediately after birth. Feeding NEG supported higher colostrum IgG concentrations. Blood mineral concentrations and blood gas balance tended to differ, but the effects were not consistent across DCAD and Ca.

Effects of heat stress and dietary zinc source on performance and mammary epithelial integrity of lactating dairy cows.

Dietary Zn and heat stress alter gut integrity in monogastric animals. However, effects of Zn on mammary epithelial integrity in heat-stressed lactating dairy cows have not been studied. Multiparous lactating Holstein cows (n = 72) were randomly assigned to 1 of 4 treatments with a 2 × 2 factorial arrangement to study the effects of environment and Zn source on performance and mammary epithelial integrity. Treatments included 2 environments [cooled (CL) or not cooled (NC)] and 2 Zn sources [75 mg/kg of supplemental Zn as Zn hydroxychloride (IOZ) or 35 mg/kg of Zn hydroxychloride + 40 mg/kg of Zn-Met complex (ZMC)]. The experiment was divided into baseline and environmental challenge phases of 84 d each. All cows were cooled during the baseline phase (temperature-humidity index = 72.5), whereas NC cows were not cooled during environmental challenge (temperature-humidity index = 77.7). Mammary biopsies were collected on d 7 and 56 relative to the onset of environmental challenge to analyze gene expression of claudin 1, 4, and 8, zonula occludens 1, 2, and 3, occludin, and E-cadherin and protein expression of occludin and E-cadherin. Deprivation of cooling increased respiration rate (64.8 vs. 73.9 breaths/min) and vaginal temperature (39.03 vs. 39.94°C) and decreased dry matter intake (26.7 vs. 21.6 kg/d). Energy-corrected milk yield decreased for NC cows relative to CL cows (24.5 vs. 34.1 kg/d). An interaction between environment and Zn source occurred for milk fat content as CL cows fed ZMC had lower milk fat percentage than other groups. Relative to CL cows, NC cows had lower concentrations of lactose (4.69 vs. 4.56%) and solids-not-fat (8.46 vs. 8.32%) but a higher concentration of milk urea nitrogen (9.07 vs. 11.02 mg/mL). Compared with IOZ, cows fed ZMC had lower plasma lactose concentration during baseline and tended to have lower plasma lactose concentration during environmental challenge. Plasma lactose concentration tended to increase at 3, 5, and 41 d after the onset of environmental challenge in NC cows relative to CL cows. Treatment had no effect on milk BSA concentration. Cows fed ZMC tended to have higher gene expression of E-cadherin relative to IOZ. Compared with CL, NC cows had increased gene expression of occludin and E-cadherin and tended to have increased claudin 1 and zonula occludens 1 and 2 gene expression in the mammary gland. Protein expression of occludin and E-cadherin was unchanged. In conclusion, removing active cooling impairs lactation performance and affects gene expression of proteins involved in the mammary epithelial barrier, and feeding a portion of dietary zinc as ZMC improves the integrity of the mammary epithelium.

Effects of feeding betaine-containing liquid supplement to transition dairy cows.

Betaine is a natural compound found in sugar beets that serves as a methyl donor and organic osmolyte when fed to animals. The objective was to evaluate the effect of feeding betaine-containing molasses on performance of transition dairy cows during late summer in 2 trials. In early September, cows were randomly assigned to betaine (BET) or control (CON) groups either shortly after dry off (trial 1; n = 10 per treatment) or 24 d before calving (trial 2; n = 8 per treatment) based on parity and previous mature equivalent milk yield. Cows were fed common diets supplemented either with a liquid supplement made of molasses from sugar cane and condensed beet solubles containing betaine [BET, 89.1 g/kg of dry matter (DM)] or a sugar cane molasses-based liquid supplement without betaine (CON) until 8 wk postpartum. The liquid supplements had similar nutrient contents and were fed at a rate of 1.1 and 1.4 kg DM/d for pre- and postpartum cows, respectively. Starting at their entry in the studies, cows were housed in the same freestall barn without a cooling system. After calving, all cows were housed in the same barn cooled by misters and fans and milked thrice daily. Intake was recorded daily and body weight and body condition score were assessed every 2 wk. Milk yield was recorded at each milking and composition was analyzed weekly. Blood samples were collected weekly from a subset of cows to assess concentrations of metabolites and AA. No treatment effects were apparent for DM intake and body weight in the prepartum and postpartum periods. For cows enrolled at dry off, BET supported higher milk yield (45.1 vs. 41.9 kg/d) and fat content (4.78 vs. 4.34%) and elevated plasma concentrations of nonesterified fatty acids and ß-hydroxybutyrate in early lactation compared to CON. However, no differences were observed for milk yield, most milk component contents and yields, and blood metabolites between treatments for cows enrolled during the close-up period. Compared to cows in the CON group, BET cows enrolled during the far-off period tended to have lower plasma concentrations of Met, Thr, and Trp during the pre- and postpartum periods. They also had lower plasma concentrations of Lys and Phe before calving but higher plasma Gly concentration after parturition. In conclusion, feeding a betaine-containing liquid supplement from far-off through early lactation improves lactation performance but increases adipose tissue mobilization and production of ketone bodies in early lactation.

In utero heat stress decreases calf survival and performance through the first lactation.

Calves born to cows exposed to heat stress during late gestation (i.e., the dry period) have lower birth weight and weaning weight and compromised passive immune transfer compared with those born to dams that are cooled. However, it is unknown if heat stress in utero has carryover effects after weaning. The objective was to evaluate the effect of heat stress (HT) or cooling (CL) in late gestation dairy cows on the survival, growth, fertility, and milk production in the first lactation of their calves. Data of animals obtained from previous experiments conducted during 5 consecutive summers in Florida were pooled and analyzed. Cows were dried off 46d before expected calving and randomly assigned to 1 of 2 treatments, HT or CL. Cooled cows were housed with sprinklers, fans, and shade, whereas only shade was provided to HT cows. Within 4h of birth, 3.8 L of colostrum was fed to calves from both groups of cows. All calves were managed in the same manner and weaned at 49d of age. Birth weight and survival of 146 calves (HT=74; CL=72) were analyzed. Additionally, body weight, growth rate, fertility, and milk production in the first lactation from 72 heifers (HT=34; CL=38) were analyzed. As expected, HT calves were lighter (means ± SEM; 39.1±0.7 vs. 44.8±0.7kg) at birth than CL calves. Cooled heifers were heavier up to 1yr of age, but had similar total weight gain (means ± SEM; 305.8±6.3 vs. 299.1±6.3kg, respectively) compared with HT heifers. No effect of treatment was observed on age at first insemination (AI) and age at first parturition. Compared with CL heifers, HT heifers had a greater number of services per pregnancy confirmed at d 30 after AI, but no treatment effect was observed on number of services per pregnancy confirmed at d 50 after AI. A greater percentage of CL heifers reached first lactation compared with HT heifers (85.4 vs. 65.9%). Moreover, HT heifers produced less milk up to 35wk of the first lactation compared with CL heifers (means ± SEM; 26.8±1.7 vs. 31.9±1.7kg/d), and no difference in body weight during lactation was observed (means ± SEM; HT: 568.4±14.3kg; CL: 566.5±14.3kg). These data suggest that heat stress during the last 6wk of gestation induces a phenotype that negatively affects survival and milk production up to and through the first lactation of offspring.

Short communication: Effect of maternal heat stress in late gestation on blood hormones and metabolites of newborn calves.

Maternal heat stress alters immune function of the offspring, as well as metabolism and future lactational performance, but its effect on the hormonal and metabolic responses of the neonate immediately after birth is still not clear. The objective of this study was to investigate the blood profiles of hormones and metabolites of calves born to cows that were cooled (CL) or heat-stressed (HS) during the dry period. Within 2 h after birth, but before colostrum feeding, blood samples were collected from calves [18 bulls (HS: n=10; CL: n=8) and 20 heifers (HS: n=10; CL: n=10)] born to CL or HS dry cows, and hematocrit and plasma concentrations of total protein, prolactin, insulin-like growth factor-I, insulin, glucose, nonesterified fatty acid, and ß-hydroxybutyrate were measured. Compared with CL, HS calves had lower hematocrit and tended to have lower plasma concentrations of insulin, prolactin, and insulin-like growth factor-I. However, maternal heat stress had no effect on plasma levels of total protein, glucose, fatty acid, and ß-hydroxybutyrate immediately after birth. These results suggest that maternal heat stress desensitizes a calf's stress response and alters the fetal development by reducing the secretion of insulin-like growth factor-I, prolactin, and insulin.

Effect of maternal heat stress during the dry period on growth and metabolism of calves.

Preliminary studies suggest that maternal heat stress (HS) during late gestation exerts carryover effects on a calf's insulin response after weaning, but a comprehensive evaluation of how maternal HS affects calf intake, growth, and metabolic response from birth to weaning is lacking. Our objective was to evaluate the effects of maternal HS during the dry period on dry matter intake, growth, and metabolism from birth to weaning. After birth, 20 heifers born to either HS (n=10) or cooled (CL, n=10) dry cows were immediately separated from their dams and fed 3.8 L of colostrum from a common pool within 4h of birth. All heifers were managed identically and weaned at 49 d of age (DOA). Calf starter intake was recorded daily, and body weight was assessed at birth and every 2 wk from birth to 56 DOA. Blood samples were collected twice a week until 56 DOA to assess hematocrit and concentrations of insulin and metabolites. To evaluate metabolic responses to maternal HS, a glucose tolerance test, insulin, and epinephrine challenge were performed on 3 consecutive days for all heifers at 8, 29, and 57 DOA. Maternal HS during the dry period did not affect heifer birth weight. Compared with HS, CL calves consumed more starter (0.53 vs. 0.34kg/d) from birth to 56 DOA and were heavier (71.7 vs. 61.4kg) at 56 DOA. Relative to HS calves, CL calves tended to have higher hematocrit (27.4 vs. 24.7%). No differences were found between treatments in plasma concentrations of insulin and glucose, but HS calves had higher nonesterified fatty acids and ß-hydroxybutyrate concentrations after 32 DOA. Compared with CL, HS calves had a faster glucose clearance after a glucose tolerance test and a slower insulin clearance after an insulin challenge. In conclusion, maternal HS during late gestation reduces calf starter intake and growth, alters blood metabolite profile, and increases noninsulin-dependent glucose uptake.

Effect of heat stress during late gestation on immune function and growth performance of calves: isolation of altered colostral and calf factors.

Calves born to cows exposed to heat stress during the dry period and fed their dams' colostrum have compromised passive and cell-mediated immunity compared with calves born to cows cooled during heat stress. However, it is unknown if this compromised immune response is caused by calf or colostrum intrinsic factors. Two studies were designed to elucidate the effects of colostrum from those innate to the calf. The objective of the first study was to evaluate the effect of maternal heat stress during the dry period on calf-specific factors related to immune response and growth performance. Cows were dried off 46 d before expected calving and randomly assigned to 1 of 2 treatments: heat stress (HT; n=18) or cooling (CL; n=18). Cows of the CL group were housed with sprinklers, fans and shade, whereas cows of HT group had only shade. After calving, the cows were milked and their colostrum was frozen for the subsequent study. Colostrum from cows exposed to a thermoneutral environment during the dry period was pooled and stored frozen (-20 °C). Within 4h of birth, 3.8L of the pooled colostrum from thermoneutral cows was fed to calves born to both HT and CL cows. Day of birth was considered study d 0. All calves were exposed to the same management and weaned at d 49. Blood samples were collected before colostrum feeding, 24h after birth and twice weekly up to d 28. Total serum IgG concentrations were determined. Body weight was recorded at birth and at d 15, 30, 45, and 60. Relative to CL calves, HT calves were lighter at birth (38.3 vs. 43.1 kg), but no difference in weight gain was observed at d 60. Additionally, HT calves had lower apparent efficiency of IgG absorption (26.0 vs. 30.2%), but no differences were observed for total IgG concentration. The objective of the second study was to evaluate the isolated effect of the colostrum from HT cows on calf immune response and growth performance. The experimental design was identical to the first study, but all calves were born to cows under thermoneutral conditions during the dry period. At birth, calves were blocked by sex and birth weight and then randomly assigned to 1 of 2 treatments, which meant they received pooled colostrum from HT cows or CL cows. No treatment effect was observed on passive immune transfer or on postnatal growth. Thus, heat stress during the last 6 wk of gestation negatively affects the ability of the calf to acquire passive immunity, regardless of colostrum source.

Short communication: Maternal heat stress during the dry period alters postnatal whole-body insulin response of calves.

Heat stress during the dry period not only negatively affects a cow's performance but also affects her offspring. Previous studies indicate that calves born to cows heat-stressed during late gestation have lower birth weight but similar overall weight gain during the prepubertal period compared with those cooled in utero. However, it is unclear if whole-body insulin response, and thus metabolism, of calves is altered in their postnatal life after in utero heat stress. The aim of the present study was to examine the effects of maternal heat stress during the dry period on whole-body insulin response of calves after weaning. Calves (10/treatment) were born to cows exposed to heat stress (HT) or cooling (CL) when dry. Calves were immediately separated from their dams and fed 3.8L of high-quality colostrum within 1h after birth and then 1.9L 12h later. All calves were fed 1.9 to 3.8L of pasteurized milk in the morning and afternoon from 2 to 42 d of age and then only in the morning until weaning at 49 d. Calf starter and water were offered ad libitum starting at 2 d of age. All calves were managed in the same manner throughout the study. All calves were subjected to a glucose tolerance test (GTT) and an insulin challenge (IC) at 55 d of age. Calves heat-stressed in utero were born lighter (40 ± 1.4 vs. 45 ± 1.4 kg) compared with CL calves. Both groups of calves had similar weaning weights (HT: 68 ± 3.2 kg; CL: 71 ± 3.3 kg) and body weight gain from birth to weaning (HT: 28 ± 2.2 kg; CL: 26 ± 2.3 kg). Compared with those cooled in utero, HT calves had a similar insulin response to GTT and insulin clearance during IC but faster glucose clearance during GTT and IC. In conclusion, in addition to impaired fetal growth, maternal heat stress during the dry period enhances the whole-body insulin response of calves after weaning, which suggests the possibility of accelerated lipogenesis and fat deposition in early life.

Source apportionment of polycyclic aromatic hydrocarbons in surface soil in Tianjin, China.

Principal component analysis and multiple linear regression were applied to apportion sources of polycyclic aromatic hydrocarbons (PAHs) in surface soils of Tianjin, China based on the measured PAH concentrations of 188 surface soil samples. Four principal components were identified representing coal combustion, petroleum, coke oven plus biomass burning, and chemical industry discharge, respectively. The contributions of major sources were quantified as 41% from coal, 20% from petroleum, and 39% from coking and biomass, which are compatible with PAH emissions estimated based on fuel consumption and emission factors. When the study area was divided into three zones with distinctive differences in soil PAH concentration and profile, different source features were unveiled. For the industrialized Tanggu-Hangu zone, the major contributors were cooking (43%), coal (37%) and vehicle exhaust (20%). In rural area, however, in addition to the three main sources, biomass burning was also important (13%). In urban-suburban zone, incineration accounted for one fourth of the total.

Stephanotic acid, a novel cyclic pentapeptide from the stem of Stephanotis floribunda.

The stem of Stephanotis floribunda afforded a new cyclic pentapeptide stephanotic acid (1), possessing a novel 6-(leucin-3'-yl) tryptophan skeleton. The structure of 1 was assigned on the basis of extensive NMR experiments and a chemical reaction and shown to be closely related to the bicyclic octapeptide moroidin (3), a toxin from Laportea moroides.

[The further studies on the pharmacological actions of Bupleurum smithii var. parvifolium].

Bupleurum smithii var. parvifolium grown widely in Ningxia, had a long history as a common medicinal herb. Its crude saponin had significant protective effect in hepatic damage caused by CCl4 in mice, its ether extract had significant analgesic effect. The ether extract also had significant immunological facilitation effect in mice, it could increase the thymus gland weight and the serum IgG content. These results were similar to or better than that of B. chinense and indicated that B. smithii var. parvifolium could be used as B. chinense.

Hazard assessment of germanium supplements.

Germanium-containing dietary supplements became popular in the 1970s in Japan and later in other countries, as elixirs for certain diseases (e.g., cancer and AIDS). Germanium is not an essential element. Its acute toxicity is low. However, at least 31 reported human cases linked prolonged intake of germanium products with renal failure and even death. Signs of kidney dysfunction, kidney tubular degeneration, and germanium accumulation were observed. Other adverse effects were anemia, muscle weakness, and peripheral neuropathy. Recovery of renal function is slow and incomplete even long after germanium intake was stopped. The total dose of ingested germanium (as dioxide, carboxyethyl germanium sesquioxide, germanium-lactate-citrate, or unspecified forms) varied from 15 to over 300 g; the exposure duration varied from 2 to 36 months. In laboratory animals, elevated germanium in tissues and impaired kidney and liver function were observed in a life-time drinking water (5 ppm germanium) study. Other toxicities associated with ingested germanium products in human cases were also demonstrated in animal studies with germanium dioxide and sometimes other germanium compounds. Based on the evidence of persistent renal toxicity associated with germanium dioxide, the lack of conclusive findings of differential nephrotoxicity of organic germanium compounds, and the possibility of contamination of the organic germanium products with inorganic germanium, it is clear that germanium products present a potential human health hazard.