Biomedical subjects

R W Hemken

Publications and source records attributed to R W Hemken.

At least 37 records · Page 2Linked to original sources

PubMed1991

Tall fescue endophyte: effect on congenital development and pup growth in mice.

This study was designed to assess effects of a diet containing endophyte (Acremonium coenophialum)-infected tall fescue seed on litter growth and development in mice. Twenty pairs of mature CD-1 mice were allocated to dietary treatments containing 50% (wt/wt) rodent chow plus either 50% endophyte-infected tall fescue seed or seed that was not infected. At parturition, six pups of approximately equal BW and sex ratio were selected from each litter and fostered to each of the dams for suckling, resulting in four suckling groups. Pups born to dams fed the infected diet weighed less at birth and experienced developmental delays in BW gain and in eye opening (16.7 vs. 13.7 d) regardless of the foster dam's diet. Pups born of dams fed the diet that was not infected attained the greatest growth rates and weaning weights; those suckling dams fed the diet that was not infected demonstrated the largest gains. Pups born of and suckled by dams fed the infected diet demonstrated greatly reduced growth rates and weaning weights compared with the other groups. Results suggest that the congenital effect on pups born of dams fed an infected diet was significant in lowering the growth rate of the pups during suckling. The dam's ability to provide nourishment to the pups also was lowered when fed this diet. When these two factors were combined, the differences were greater than for either factor separately.

Acremonium↗

PubMed1991

Influence of calcium chloride on systemic acid-base status and calcium metabolism in dairy heifers.

Twenty heifers (12 Holsteins and 8 Jerseys) ranging from 15 to 22 mo of age (SD = 2.2 mo) and weighing 271 to 486 kg (SD = 72 kg) were offered diets containing 0, .5, 1, and 1.5% CaCl2 for 3 wk followed by a 1-wk readjustment period to evaluate the effect of CaCl2 on acid-base status, diuresis, and Ca metabolism. These evaluations were conducted under conditions simulating changes in dietary cation-anion balance that potentially can be utilized as prophylaxis for parturient paresis during transition from dry cow period to lactation. Free proton concentration in blood increased and blood bicarbonate decreased with increasing dietary CaCl2. Plasma protein and blood hematocrit were unaffected by dietary CaCl2. Plasma Ca and urinary hydroxyproline excretion also were unaffected, but urinary Ca excretion rose with increasing dietary CaCl2, possibly reflecting either increased bone mobilization or intestinal absorption of Ca. Elevating dietary Cl increased both plasma Cl and urinary Cl excretion. During the readjustment period, all differences caused by CaCl2 disappeared. Based on the responses of acid-base status and Ca metabolism to the different dietary concentrations of CaCl2, we suggest that feeding 1% CaCl2 to dry cows for 3 wk prepartum could be a suitable method to prevent parturient paresis without causing detrimental acid-base disturbances.

Acid-Base Equilibrium↗

PubMed1991

Endotoxin mastitis in cows milked four times daily.

As part of a project to identify the pathophysiological cause or causes of mastitic hypogalactia, midlactation cows were infused in two homolateral quarters with 10 micrograms of endotoxin while being milked four times daily to resolve better the temporal changes in mammary synthetic activity during endotoxin mastitis. Milk fat was decreased by the first milking (5 h) postinfusion and then recovered rapidly. In contrast, milk yield and the yields of protein and lactose were not significantly inhibited until the second milking, and these yields recovered slowly thereafter. The decline in milk yield by infused quarters was only 20% greater than the decline by uninfused quarters in this experiment. Mammary inflammation developed rapidly in infused quarters as milk serum albumin concentration was maximal at the first milking. Milk SCC and NAGase were also elevated at this time, and maximal levels occurred at milkings 2 to 4. Increased temperature, increased cortisol, and a mild anorexia were apparent at the first milking only. Endotoxin treatment had no effect on serum prolactin or glucose. These data suggest that the delayed hypogalactia is consequent to the mammary inflammation and systemic responses following endotoxin infusion. The results indicate that different pathophysiological events may inhibit synthesis of the different milk components.

Animals↗

PubMed1991

Role of magnesium in the dietary cation-anion balance equation for ruminants.

Eight midlactation Holstein cows (four primiparous) were assigned to replicated 4 x 4 Latin squares with a 2 x 2 factorial arrangement of treatments. The basal diet was formulated to contain 0 milliequivalents (Na + K) - Cl/100 g of diet DM. Treatment diets of high and low dietary cation-anion balance were achieved by adding appropriate amounts of supplemental Na + K (added on an equivalent basis) or Mg to the basal diet. Milk and protein yield were increased as well as DMI and FCM for Na + K diets The high concentration of cation increased milk fat percentage. The cation-anion balance (using Mg as a cation) had no effect on any of the production parameters observed. The higher cation-anion balances increased blood bicarbonate levels and plasma Na. Urinary Ca excretion was increased for the Mg diets. Urinary pH increased with both the source of cation (Na + K) and the concentration of cation (high) in the diet. other minerals were unaffected in milk, plasma, or urine. Responses measured in this trial reflect treatments calculated using the equation milliequivalents (Na + K) - Cl/100 g diet DM or (Na + K) - (Cl + S)/100 g diet DM, suggesting that Mg plays a minor role in dietary cation-anion balance.

Animal Feed↗

PubMed1991

Effects of copper status on neutrophil function, superoxide dismutase, and copper distribution in steers.

Twelve Holstein steers in a completely randomized block design were fed either a basal diet (concentrate:silage or hay at a DM ratio of 35:65) plus Cu sulfate at 20 ppm of Cu (Cu-supplemented diet) or a basal diet plus ammonium molybdate to obtain 10 ppm of Mo (Cu-depleting diet) on a DM basis in the whole diet for 8 mo. Supplemental Mo was utilized in the Cu-depleting diet to develop a Cu-deficient group. Molybdenum slowly accumulated in the liver in the group fed the Cu-depleting diet. Copper concentrations in the liver and polymorphonuclear neutrophils decreased in the Cu-deficient group compared with the Cu-sufficient group. Plasma Cu concentration did not change during the trial for the Cu-sufficient group. In the Cu-deficient group, plasma Cu concentrations increased during the first 3 mo of the trial, then declined, and remained unchanged for the last 5 mo. Superoxide dismutase activities in red blood cells, polymorphonuclear neutrophils, and whole blood decreased in the Cu-deficient group. Phagocytic capacity was not affected by Cu status, but killing capacity was decreased by low Cu status in the Cu-deficient group by the end of the trial. Glutathione peroxidase activity was unaffected by Cu status. Clinical symptoms of Cu-deficiency were not observed in this trial; there was no evidence of blood hemoglobin or BW gain difference between the two groups. In this study, Cu status affected its distribution in the tissues and related enzyme activities as well as bactericidal function of neutrophils.

Animals↗

PubMed1991

Effects of copper sources and dietary cation-anion balance on copper availability and acid-base status in dairy calves.

Twenty-four Holstein and Jersey calves (14 Holstein), 4 to 11 d of age, were assigned randomly to six treatments in a 2 x 3 factorial arrangement to examine the effects of Cu sources and dietary cation-anion balance on Cu availability and acid-base balance. Treatments were cationic basal diet (20 meq of dietary cation-anion balance on a DM basis), cationic basal diet supplemented with CuO, cationic basal diet supplemented with CuSO4, anionic basal diet (-10 meq), anionic basal diet supplemented with CuO, and anionic basal diet supplemented with CuSO4. Copper sources did not show any effect on growth of calves. The cationic diet increased calf growth compared with the anionic diet at wk 12 of the experiment. Blood pH was increased by the cationic diet in comparison with the anionic diet at wk 8 and 12. Blood pH also was increased by CuSO4 compared with CuO treatment in the early period of the treatment. Blood bicarbonate concentration was decreased by CuO and the anionic diet. Interactions between Cu sources and cation-anion balance were found for blood pH and bicarbonate concentration. Liver Cu concentration was increased by CuSO4 but not by CuO supplementation compared with control. Therefore, CuSO4 was found to be highly available, whereas CuO was a very poorly available source of Cu for young calves.

Acid-Base Equilibrium↗

PubMed1991

Reduced lactational performance following intravenous endotoxin administration to dairy cows.

Nonpregnant lactating cows were given 100 micrograms of endotoxin via the jugular vein to determine effects of intravenous endotoxin administration on mammary inflammation and lactational performance. At the first milking (11 h) posttreatment, milk yield was reduced 33%. Milk fat percentage was elevated at this time, but lactose concentration was decreased. Milk yield and composition returned to pretreatment levels within 2 d. Clinical mastitis was not induced by endotoxin treatment, but milk SCC, NAGase, serum albumin, and lactoferrin were increased by 50%. This increase was small compared with increases during mastitis and may have resulted from lower milk volume. These results support the hypothesis that part of the reduced lactational performance during endotoxin mastitis is mediated by systemic pathophysiological responses and indicate that intravenous endotoxin administration may be a useful model to study adverse effects of infectious disease on lactational performance.

Animals↗

PubMed1991

Suppression of milk production during endotoxin-induced mastitis.

Healthy, midlactation cows were given intramammary infusions of 10 micrograms of endotoxin in two homolateral quarters. Productive, inflammatory, and systemic responses were studied to investigate the pathophysiological effects of mastitis on lactational performance. Endotoxin suppressed milk yield in all quarters of treated cows. A more severe and prolonged suppression occurred in infused quarters compared with uninfused quarters. The fat percentage of milk from all quarters was increased with a greater increase occurring in infused quarters. The protein composition of milk was elevated, and the lactose concentration was depressed in infused quarters. Mammary inflammation--as measured by milk SCC, NAGase, serum albumin, and lactoferrin--was limited to infused quarters. Changes in milk NAGase closely paralleled changes in milk SCC. Daily feed intake was unaffected, and serum glucose levels did not decline following infusion. The lactose concentration of urine increased rapidly after infusion. Reduction in milk yield in all quarters, but varying changes in milk composition in infused versus uninfused quarters suggest that mastitic hypogalactia is mediated by multiple pathophysiological events and is not solely due to inflammatory damage to the mammary epithelium. Part of the reduced lactational performance may result from escape of milk components from the udder into the circulation.

Acetylglucosaminidase↗

PubMed1991

Effect of dietary energy and previous bovine somatotropin on milk yield, mastitis, and reproduction in dairy cows.

Thirty multiparous lactating Holstein cows were blocked according to time of calving and assigned to a 2 x 3 factorial arrangement of treatments in a randomized complete block design to evaluate the effects of two dietary energy concentrations either without or with bST (20.6 mg/d per cow) administered to cows that had not or had received bST during the preceding lactation. Subcutaneous injection of bST began 28 to 35 d postpartum and continued for 39 wk. The dietary energy concentration x bST interaction was not significant for any response variable. Compared with DMI of control cows, DMI was higher for cows receiving bST, being 1.6 and 2.4 kg/d higher for cows receiving bST for one and two lactations, respectively. Milk, fat, and protein yields were higher for cows receiving bST than for controls. Those receiving bST for a second lactation also produced more milk than controls until wk 20; thereafter, milk yields were similar to those of controls. Somatotropin administration had no adverse effect on udder health. Cows receiving bST tended to ovulate less regularly than controls, which may be attributed to their higher milk yield. However, BW gains during lactation were similar for all treatments, indicating that bST-treated cows built energy reserves for the subsequent lactation. Although energy concentrations of the diets had no significant impact on yield, the higher energy diet tended to depress milk fat concentration. Administration of bST to dairy cows for a second, consecutive lactation yielded responses similar for the first 20 wk of the study to those receiving bST for the first time. However, after wk 20, milk yield was less than that by cows receiving bST for the first lactation but similar to that of control cows.

Animals↗

PubMed1990

Interactions of dietary cation-anion balance and phosphorus: effects on blood, bone and faecal phosphorus concentration in dairy calves.

Dietary levels of cations and anions are shown to have an effect on concentrations of phosphorus (P) in blood, bone and faeces of dairy calves between 9 and 19 weeks of age. Calves fed diets high in anions, demonstrated higher concentrations of P in blood and faeces than calves whose diets were high in cations, and at the same time demonstrated lower concentrations of P in bone. Compared to diets with high cation levels, diets high in anions produced significantly (p less than 0.05) higher concentrations of total P in the faeces at different stages in the experiment, higher serum inorganic phosphorus (SiP) concentrations and lower P concentrations in the bone, which were significant at the end of the trial (P less than 0.06). When the diet was low in P (0.22%), the cation-anion balance of the diet seemed to have the greatest effect, so that the interaction of dietary P and dietary cation-anion balance (DCAB) was responsible for changes in blood, bone and faeces.

Animal Feed↗

PubMed1989

Effects of feeding endophyte infected tall fescue seed on reproductive performance of female CD-1 mice via competitive breeding.

This study was conducted to determine the effects of feeding endophyte-infected (Acremonium coenophialum ) tall fescue (Festuca arundinacea ) seed on the growth and reproductive performance of female CD-1 mice via competitive breeding. One hundred sixty female mice were randomly allocated to groups of ten and fed one of two diets. Diet 1 consisted of 50% mouse chow and 50% noninfected Ky-31 tall fescue seed (w/w). Diet 2 contained 50% chow and 50% tall fescue seed that was 80% infected with A. coenophialum . After 50 d of preconditioning on their respective diets, a single male was introduced into each group of 10 females and allowed to cohabitate for 96 h. The males were removed after the cohabitation period and the females continued through gestation on their respective diets. Body weight of dams and litter weights were recorded at parturition. There were no differences (P>0.05) in pregnancy rates between dietary Treatments 1 and 2 (50% vs 48.8%, respectively). However, the average number of pups born per litter (11.10 pups) and average total litter weight (17.21 g) was greater for those females consuming Diet 1 than for females consuming Diet 2 (9.33 pups per litter and 13.97 g total litter weight). The incidence of dead and cannibalized pups was more frequent with Diet 2 than Diet 1 (0.13 vs 0.0 dead; 0.21 vs 0.03 cannibalized, respectively). The obtained data suggest that although the pregnancy rate was similar between the two dietary treatments, the reproductive capacity (litter size and litter weight) of female CD-1 mice was affected by the consumption of endophyte infected fescue seed.

Journal Article↗

PubMed1989

Physiological responses in rats fed extracts of endophyte-free and endophyte-infected tall fescue seed relative to some known ergot alkaloids.

Ethanol and ethanol-water extracts of endophyte-infected tall fescue seed were effective for extracting toxin(s) responsible for feed intake and average daily weight gain (ADG) depression in Sprague Dawley rats. Although the ethanol extract of endophyte-infected seed depressed serum prolactin (Prl) concentrations, the data were less reflective of overall toxicity than feed intake and weight gain. Inclusion of commercially available ergonovine maleate, ergocryptine and ergotamine tartrate had no effect on rat feed intake, ADG or serum Prl at the levels tested. Dietary addition of a recombination of hexane, ethanol and ethanol-water extracts caused a toxicity response (depressed feed intake, ADG, and serum Prl) equivalent to that of the whole seed. The toxic factor(s) were extracted primarily in more polar solvents such as ethanol and ethanol-water. Rat assays can be used successfully in lieu of cattle assays as a routine evaluation of toxic components in endophyte-infected tall fescue. However, species differences dictate that eventually all suspected toxins be evaluated in the bovine.

Animals↗

PubMed1989

Effect of reactivity rate and particle size of magnesium oxide on magnesium availability, acid-base balance, mineral metabolism, and milking performance of dairy cows.

Four ruminally fistulated Holstein cows were arranged in a 4 x 4 Latin-square design. Treatments consisted of a control diet and three diets containing 4% MgO (DM basis) with increasing reactivity rates (A, B, C). Diets contained corn silage and concentrate at a 40:60 ratio (DM) and were fed at 95% of ad libitum intake. Total acid-consuming capacity and solubility of MgO in vitro paralleled particle size and agreed with the solubilities in the rumen. Milk fat percentage, but not milk yield, was increased by all three MgO diets. Ruminal pH was elevated by the MgO diets across all 8 h postfeeding. MgO, reactivity A diet tended to increase ruminal acetate, total VFA production, milk yield, milk fat yield, and milk fat percentage. Effect of time postfeeding on acetate and propionate production was significant; 2 to 6 h postfeeding was the period most responsive to the diets. No significant influence on blood acid-base balance was observed. On the basis of urinary excretion of Mg, MgO sources with smaller particles are more available to cattle. Both Ca and Cl metabolism appeared to be affected by reactivity rate of MgO.

Acid-Base Equilibrium↗

PubMed1989

Effects of sodium bicarbonate and sodium sesquicarbonate on animal performance, ruminal metabolism, and systemic acid-base status.

Six rumen-fistulated lactating Holstein cows were arranged in a replicated 3 x 3 latin square design with 3-wk periods and offered diets containing concentrate and corn silage in a 60:40 ratio (DM basis). Treatments were: 1) basal diet, 2) basal diet with 1% NaHCO3, and 3) basal diet with 1% sodium sesquicarbonate. There were no differences among treatments in milk production, milk protein, or 3.5% FCM, but sodium sesquicarbonate increased milk fat percentage (3.89, 3.94, 4.06%) compared with that of the control. Rumen pH was higher for cows fed buffered diets than for control cows. Urine pH was higher for cows fed NaHCO3 diet than for those fed sodium sesquicarbonate and control diets. No differences were detected among treatment means for molar percentage of isobutyrate, isovalerate, or total VFA, Dietary sesquicarbonate addition increased molar percentage of acetate, decreased propionate, and resulted in a higher acetate:propionate ratio compared with the cows fed NaHCO3. However, molar percentage of butyrate and valerate decreased in cows fed sodium sesquicarbonate when compared with those fed the control diet. No differences among treatment means were detected for blood pH, pCO2, or HCO3.

Acid-Base Equilibrium↗

PubMed1988

Effects of feeding endophyte-infected (Acremonium coenophialum ) KY-31 fescue hay on the reproductive development of Holstein bulls.

This study was designed to assess the effect of endophyte-infected (Acremonium coenophialum ) tall fescue (KY-31) on reproductive development in bulls. Eighteen Holstein bull calves (2 mo old) were randomly allocated to one of two dietary treatments consisting of 1) noninfected KY-31 fescue hay (NON) supplemented with grain (n=9) and 2) infected (67% infected by Acremonium coenophialum ) KY-31 fescue hay (INF) supplemented with grain (n=9). Both dietary treatments consisted of equal amounts of hay and grain. Data were collected every 14 d. Body weight, hip height and scrotal circumference did not differ (P>0.05) in the two treatments. Mean rectal temperatures also were not different in bulls (P = 0.12); however the infected bulls experienced higher rectal temperatures in all but four collection periods. Animals were sacrificed at 13 mo of age. Testicular weight and dimensions, epididymal weight and length as well as seminal vesicle weight were not different (P>0.05). Maturity of spermatozoa taken from each cauda epididymides was assessed by the incidence of cytoplasmic droplets and was not different (P>0.05) between treatments. Daily sperm production potential was not different (P>0.05) between treatments; however, large variations were noted among the infected bulls. Blood testosterone levels were not different (P=0.29) between the two dietary treatments, but were different over time (P<0.001) with NON and INF bulls having 2.14 +/- 0.21 and 2.41 +/- 0.22 ng/ml, respectively. Prolactin levels were different (P<0.02) between the NOn and INF bulls, 29.35 +/- 3.35 vs 18.31 +/- 3.39 ng/ml, respectively; and over time (P<0.001). The data generated in this study showed some important biological trends. Overall, the results indicate that endophyte infected KY-31 fescue hay fed to growing bulls did not appear to have severe detrimental effects on body growth or reproductive development. However, additional studies will be necessary to further delineate the patterns established in this study.

Journal Article↗

PubMed1988

Lactation in mice fed endophyte-infected tall fescue seed.

This study was conducted to assess the effects of endophyte-infected Acremonium coenophialum tall fescue (KY-31) seed (80% infected) on lactation in CD-1 dams and suckling performance of pups as measured by pup survival and growth rates. Twenty-four pairs of mature CD-1 mice were randomly allocated to four dietary treatments: 1) 100% mouse chow ad libitum; 2) 40% endophyte-infected tall fescue seed and 60% mouse chow (w/w); 3) reduced intake (100% chow), adjusted daily to the intake level of Treatment 2; and 4) 60% infected tall fescue seed and 40% chow. The mice were preconditioned on their respective diets for 100 d prior to 96 h of cohabitation between pairs of males and females. At parturition the litters were removed, and each dam was given a litter of six pups of equal weight, size and sex ratio to suckle for 15 days. All pups given to all the dams were born to other mice that were not part of the study and had not been exposed to endophyte-containing diets. Dams and litter weights were measured daily for 15 consecutive days. The combined body weight measurements of litters from dams fed the tall fescue containing diets (Treatments 2 and 4) were significantly lower (2.07 +/- 0.41 g/d) than that of litters from dams fed the chow containing diets (Treatments 1 and 3) during the suckling trial (P<0.05). Similarly, nine of ten (90%) dams fed the chow containing diets maintained five or more pups (5.5 +/- 0.2) throughout the study as compared to five of nine (55.6%) dams fed the tall fescue containing diets that maintained less than five pups (4.5 +/- 0.2).

Journal Article↗

PubMed1988

Reproductive responses in male rats fed extracts of fescue seed infected by the endophytic fungus Acremonium coenophialum.

This study was undertaken to determine whether a methanol extract of endophyte-infected tall fescue seed contained the factor(s) that were responsible for the decrease in male reproductive potential when rats were fed toxic tall fescue seed. Twenty-four Sprague-Dawley male rats (ca. 225 g.) were randomly allocated to one of three dietary treatments containing 50% (w/w) rodent chow and 50%: (1) noninfected tall fescue seed; (2) noninfected tall fescue seed treated with concentrated methanol effluent from serial methanol extraction of infected seed; and (3) the extracted seed residue of seed that was greater than 95% infected by Acremonium coenophialum. Parameters assessed were testicular weight, epidydimal weight, parenchymal weight, progressive sperm motility, sperm motility, sperm count and daily sperm production potential. Significant reduction (P less than 0.05) for feed intake, average daily gain, testicular weight, epidydimal weight and daily sperm production potential were observed for treatment 2. These data suggest that the serial methanol extract contains the factor(s) responsible for the lowered reproductive potential in male rats. The extract contained 15,578 micrograms/ml of pyrrolizidine alkaloids and only trace amounts of ergopeptides. These results suggest that N-formyl and N-acetyl loline may play an important role in the fescue toxicity noted in the exposed rats.

Acremonium↗

PubMed1988

Effect of feeding tall fescue seed infected with endophytic fungus (Acremonium coenophialium) on the estrous cycle in CD-1 mice.

The objective of this study was to assess the effects of endophyte-infected tall fescue (G1-307) seed (80% infected, by Acremonium coenophialum) on the estrous cycle in CD-1 mice. Twelve 60-day-old CD-1 female mice were randomly allocated to one of two dietary treatments containing 50% laboratory chow and (1) 50% endophyte-free (noninfected) fescue seed; (2) 50% endophyte-infected fescue seed. All mice were fed ad libitum. On day 35 of the study all mice were allowed access to a diet containing 100% laboratory chow for 7 days. Vaginal smears of each female were prepared daily throughout the 42 day trial period. All vaginal smears were stained and evaluated to determine phase of the estrous cycle. The days (+/- SE) to the first abnormal occurrence in the estrous cycle for treatments one and two were 27.0 +/- 5.6 and 16.7 +/- 5.2, respectively. The percent abnormal cycles of the total cycles observed between treatments one and two were 20.5 +/- 6.1 and 39.3 +/- 12.5, respectively. Mice on treatment two exhibited a greater frequency of abnormal sequences of the phases of the estrous cycle and greater cycle length (P less than 0.05). The results suggest that the infected fescue seed had a significant effect on the estrous cycle of the mouse (P less than 0.05).

Acremonium↗