The Effect of Concentrate Feeding on Calcium Metabolism and Plasma Gastrin Concentration in Parturient Cows

The effect of concentrate feeding on calcium metabolism was studied in pregnant cows. The concentrate (5 kg/day) was added to the diet about three weeks before expected calving. A control group was fed only hay during the whole dry period. It was earlier observed in sheep that concentrate feeding was followed by a disturbance in calcium homeostasis, but no such disturbances were observed in the cows. The concentrate fed cows consumed 50 % more calcium than the controls and were found to mobilize less calcium from the skeleton immediately after calving. There was no evidence for the theory that the gastro-intestinal hormone gastrin is involved in calcium homeostasis in the parturient cow.     

Effect of folic acid supplements on homocysteine concentration in plasma of gestating sows

An experiment comprising 19 German Landrace sows was established to evaluate the effect of folic acid supplements (10 mg/kg concentrate) on homocysteine and folic acid concentration in plasma and serum, respectively, of highly pregnant sows as compared to an unsupplemented control (basal diet contained 0.62 mg folic acid/kg concentrate). Blood samples were taken between day 75 and 110 of gestation for homocysteine analysis and on day 100 of gestation for folic acid determination. Due to the folic acid supplements serum folic acid concentration increased significantly (104 nmol/1 in controls and 140 nmol/1 in supplemented sows). In contrast, homocysteine concentration in the plasma was not significantly influenced by folic acid supplements (16.6 μmol/1 in controls and 15.2 μmol/1 in supplemented sows). Further investigations seem to be necessary to clarify the physiology of homocysteine metabolism in swine.     

Effect of the rate of increase in concentrate allowance with concentrates high or low in starch on the performance of dairy cows in early lactation

The effect of the rate of increase in concentrate allowance after calving with two concentrate mixes (A and B) differing in composition was evaluated using 64 Finnish Ayrshire cows during the first 100 days of lactation. After calving, the concentrate allowance of multiparous cows was increased stepwise from 4 to 17 kg/day, and of primiparous cows from 3 to 13.5 kg/day over 12 days (F rate of increase; multiparous 1.08 kg/day, primiparous 0.88 kg/day) or 24 days (S rate of increase; mutiparous 0.54 kg/day, primiparous 0.44 kg/day). The concentrates were formulated to have similar crude protein and metabolizable energy concentrations but differing starch and NDF concentrations. For concentrate A the starch and NDF concentrations were 421 and 167 g/kg dry matter (DM) and for concentrate B 258 and 251 g/kg DM. All cows received grass silage ad libitum. The higher concentrate intake during weeks 1 to 4 of lactation with F compared with the S rate of increase caused higher DM, energy and protein intake. The higher concentrate intake for F than for S treatment in early lactation did not cause a large decrease in silage intake (8.8 v. 8.3 kg DM/day). The intake of concentrate A and B after calving did not differ for S treatment. However, for F treatment the intake of fibrous concentrate B increased faster than starch-rich concentrate A during weeks 1 to 4 of lactation. The concentrate composition had no effect on energy-corrected milk (ECM) yield during weeks 1 to 4 of lactation for S treatments, but with F treatments the cows fed B concentrate produced more milk. The F rate of increase in concentrate allowance compared with the S rate increased the calculated energy balance after calving. The rate of increase in concentrate feeding post partum or concentrate composition had no effect on DM, energy or protein intake during the whole 100-day experiment. The average ECM yield over days 1 to 100 of lactation was higher for S than for F treatments and tended to be higher with concentrate B than A. Results of this study showed that by the fast rate of increase in concentrate allowance after calving on a grass silage diet, it was possible to improve the energy status of the cows in early lactation. This had, however, no effect on production later in lactation.     

The calcium requirement and factors causing calcium loss

Studies carried out under strictly controlled conditions during different calcium intakes in adult males have shown that the average calcium balance was only slightly positive (+22 mg/day) during a calcium intake of 800 mg/day, the recommended dietary calcium intake, not taking into consideration dermal losses of calcium. During this calcium intake, the calcium balances were negative in 34% of the subjects studied. Increasing the calcium intake to 1200 mg/day resulted in a significant increase of the calcium balance; further increases to different intake levels up to 2300 mg/day did not improve the calcium balance further. Increasing the phosphorus intake up to 2000 mg/day as well as increasing the protein intake from 1 g/kg body weight to 2 g/kg, given as meat, did not have an adverse effect on calcium metabolism. A variety of drugs, notably aluminum-containing antacids, induced calcium loss. Increasing the calcium intake more than 10-fold from 200 to 2500 mg/day did not lower the blood pressure in a large number of normotensive patients and in a small number of hypertensive patients studied.     

Effect of ipriflavone on bone changes induced by calcium restricted, vitamin D deficient diet in rats

The preventive effect of ipriflavone, 7-isopropoxy-isoflavone, on the development of experimental osteopenia in rats was studied. Male Wistar rats (4 weeks old) on a calcium restricted, vitamin D deficient diet were given a daily oral administration of ipriflavone. The administration of ipriflavone (100 mg/kg BW/day) for 40 days significantly inhibited a decrease in the cortical thickness (14.0 +/- 1.6 vs. 17.1 +/- 2.9%, mean +/- SD, p less than 0.05) and bone calcium content (62 +/- 4 vs. 67 +/- 2 mg, p less than 0.05) in the femora of rats induced by a mild calcium restricted (0.3%), vitamin D deficient diet. This compound did not affect serum calcium levels in this condition. But a dose of 20 mg/kg BW/day of ipriflavone was insufficient to inhibit a decrease in bone calcium content. In rats fed on a more severe calcium restricted (0.03%), vitamin D deficient diet, the administration of ipriflavone (100 mg/kg BW/day) did not significantly affect the cortical thickness or calcium content. Intestinal calcium absorption measured by the in situ loop method was not significantly different between rats fed with a severe calcium restricted (0.03%), D deficient diet with or without ipriflavone (20 or 100 mg/kg BW/day) These results demonstrate that the new compound, ipriflavone, partially prevents bone calcium loss induced by a mild calcium restricted (0.3%), vitamin D deficient diet in rats. However, the precise mechanism of action of this compound remains unknown.     

Evaluation of concentrate factors affecting silage intake of dairy cows: a development of the relative total diet intake index

The aim of this work was to develop an index describing the relative intake of the total diet by dairy cows, and hence the ability to predict intake responses to changes in both forage and concentrate variables. An evaluation of concentrate factors affecting silage dry matter (DM) intake of dairy cows was conducted based on dietary treatment means from milk production experiments. The data were divided into four subsets according to concentrate treatments used within the experiments: the amount of concentrate supplementation (n = 217), protein supplementation (n = 336), carbohydrate composition (n = 114) and fat concentration of the concentrate (n = 29). The data were subjected to mixed-model regression analysis. Increased concentrate DM intake (CDMI) decreased silage DM intake (SDMI) quadratically. The substitution rate (substitution of silage DM for concentrate DM) increased with improved silage intake potential. SDMI increased quadratically with concentrate protein intake, the response being negatively related to the effective protein degradability (EPD) of concentrates. Replacement of starchy concentrate ingredients with fibrous supplements had a small positive effect on silage intake, whereas increased concentrate fat concentration slightly decreased SDMI. The outcome of concentrate factors influencing total DM intake (TDMI) was used to create a relative CDMI index as follows: CDMI index = 100 + 10 × [(CDMI - 0.1629 × CDMI - 0.01882 × CDMI2 - 5.49) + ((0.9474 × CCPI - 0.4965 × CCPI2) - 2.017 × (CEPD - 0.74)) + 0.00225 × (CNDF - 250) - 0.0103 × (40 - Cfat) - 0.00058 × (CDMI - 8.0) × (SDMI index - 100)], where CDMI = concentrate DM intake (kg/day), CCPI = supplementary concentrate CP intake (kg/day; CP>170 g/kg DM), CEPD = concentrate EPD (g/g), CNDF = concentrate NDF concentration (g/kg DM), Cfat = concentrate fat concentration (g/kg DM) and SDMI index is the relative intake potential of silage (Huhtanen, Rinne and Nousiainen 2007. Animal 1, 758-770). TDMI index was calculated as SDMI index + CDMI index - 100 to describe the relative intake potential of the total diet. For the whole data set (n = 943), one TDMI index unit was equivalent to 0.095 kg/day DM intake, i.e. close to the default value of 0.100 kg. The CDMI index explained proportionally 0.88 of the variation in TDMI within a study with a 0.27 kg/day residual mean-square error (n = 616). The corresponding values for the TDMI index were 0.81 and 0.37 kg/day (n = 943), respectively. The residual mean-square errors in cross-validation were marginally higher. The developed TDMI index can be used to estimate the intake responses to diet changes. It provides an improved basis for practical dairy cow ration formulation and economic evaluation.     

Gastrointestinal development of dairy calves fed low- or high-starch concentrate at two milk allowances

The objective was to study the effect of type of concentrate with varying starch and fibre content on growth and gastrointestinal development in preweaned dairy calves. Thirty-two newborn Danish Holstein male calves were allocated to four treatment groups in eight blocks of four calves. An experimental low-starch, high-molasses, high-fibre (EXP) concentrate or a traditional high-starch (TRA) concentrate were fed either at a high (HIGH; 2 × 3.2 kg/day) or a low (LOW; 2 × 1.6 kg/day) whole milk allowance in a 2 × 2 factorial design. TRA contained 350 and EXP 107 g starch/kg dry matter (DM), whereas the NDF content was 136 and 296 g/kg DM, respectively. Metabolizable energy (ME) was 11.2 and 12.2 MJ ME/kg DM in EXP and TRA, respectively. All calves had free access to artificially dried grass hay (9.8 MJ ME/kg DM). Four calves were culled during the experiment. The calves were euthanized either at 38 (12 calves) or 56 days (16 calves) of age. Evaluated across both slaughter ages, there was no difference between TRA and EXP in concentrate and hay intake, rumen weight and papillation. EXP resulted in increased villi number in duodenum and jejunum compared with TRA. Concentrate intake and reticulo-rumen weight was higher for LOW compared with HIGH milk allowance, whereas live weight gain was 20% lower. The results show that a low-starch, high-molasses, high-fibre concentrate with 8% lower ME content tended to reduce daily gain compared with a traditional calf starter concentrate, but resulted in similar ruminal development in preweaned calves both on a high and a low milk allowance fed along with grass hay. Furthermore, the results suggest that the experimental concentrate stimulated intestinal villi growth over that of the traditional concentrate.     

Influence of weather conditions on milk production and rectal temperature of Holsteins fed two levels of concentrate

Twelve lactating Holstein cows in 2nd lactation were allocated randomly, six each, to two feeding treatments: high concentrate (1 kg dairy concentrate to 2 kg milk produced) and low concentrate (1 kg dairy concentrate to 4 kg milk produced) from 7 to 106 days postcalving. Forage and water were provided adalibitum. Milk and butter fat yields and rectal temperatures were examined in relation to 9 weather variables (minimum, maximum and mean temperatures, relative humidity, temperature-humidity index (THI), radiation, wind velocity and mean temperature of the previous day). Averages for milk yield, fat yield and rectal temperature were respectively 20.4 kg, 0.7 kg and 38.9°C for the high concentrate treatment and 18.4 kg, 0.6 kg and 38.6°C for the low concentrate treatment. Weather conditions accounted for 5.6%, 0.8% and 10.8% of the day to day variation in milk yield, fat yield and rectal remperature, respectively, for the high concentrate group and 29.4%, 9.7% and 0.6%, respectively, for the low concentrate group. Only measures of ambient temperature, especially mean temperature, were closely associated with these traits.     

Effects of dietary mannanoligosaccharide on performance, some blood parameters, IgG levels and antibody response of lambs to parenterally administered E. coli O157:H7

Forty-eight male lambs were used to evaluate the effect of dietary supplementation of mannanoligosaccharide (MOS) with or without parenteral Escherichia coli injection on their growth performance, feed conversion efficiency, blood metabolites, total serum immunoglobulin G (IgG) levels and antibody response. Lambs were randomly assigned to four groups of 12 animals each. In groups C (control) and CE (E. coli challenged), animals were fed commercial concentrate pellets and hay (50:50), and in groups M (MOS) and ME (MOS + E. coli challenged), animals were fed commercial concentrate pellets including MOS at 0.2% and hay (50:50). At day 15 and 30, animals in groups CE and ME were injected subcutaneously with 1 ml of phosphate buffered saline (PBS) suspension containing 10(6) cfu of heat inactivated non-toxigenic E. coli O157:H7, while animals in C and M groups were injected subcutaneously with 1 ml of PBS. The experimental period was 45 days. Data indicated that body weight of lambs at the end of the study were statistically non-significant among the groups. Blood metabolites, i.e. total protein, albumin, calcium and phosphorus concentrations were not affected significantly by MOS supplementation. However, administration E. coli lowered (p < 0.05) total protein, albumin and calcium concentrations in the serum on day 30. The IgG level was not different between groups. However, on day 45, the total IgG level was found to be higher (p < 0.05) in lambs that had received MOS and E. coli than in other groups. Application of MOS did not have any effect on the antibody response to E. coli as OD values.     

Effect of replacing ground corn and soybean meal with licuri cake on the performance,digestibility, nitrogen metabolism and ingestive behavior in lactating dairy cows

Licuri (Syagrus coronate) cake is a biodiesel by-product used in ruminant feed as a beneficial energy source for supplementation in managed pastures. The objective was to evaluate the performance, digestibility, nitrogen balance, blood metabolites, ingestive behavior and diet profitability of eight crossbred Holstein (3/4)×Gyr (5/8) multiparous cows (480±25 kg BW and 100 days milking) grazing and supplemented with licuri cake partially replacing ground corn and soybean meal in concentrate (0, 200, 400 and 600 g/kg in dry matter (DM)), distributed in an experimental duplicated 4×4 Latin square design. Licuri cake partially replacing ground corn and soybean meal increased (P<0.01) the intake and digestibility of ether extract and decreased the non-fiber carbohydrates; however, there were no influences on the intakes of DM, CP, NDF and total digestible nutrients (TDN). The digestibilities of DM, CP and NDF were not influenced by licuri cake addition. There was a decrease trend on TDN digestibility (P=0.08). Licuri cake replacing ground corn and soybean meal in concentrate did not affect the intake; fecal, urinary and mammary excretions; N balance; and triglycerides concentrations. However, the blood urea nitrogen (P=0.04) concentration decreased with the licuri cakes inclusion in cow supplementation. There was an increasing trend for serum creatinine (P=0.07). Licuri cake inclusion did not affect body condition score, production, yield, protein, lactose, total solids and solid non-fat contents of milk and Minas frescal cheese. There was a linear decrease in average daily weight gain (g/day). The milk fat concentration and cheese fat production (P<0.1) presented a linear increase with partial replacement of ground corn and soybean meal with licuri cakes. The addition of licuri cake did not alter the time spent feeding, ruminating or idling. There was an increasing trend in NDF feeding efficiency (P=0.09). The replacing of ground corn and soybean meal with licuri cake up to 600 g/kg decreased the concentrate cost by US$0.45/cow per day. Licuri cake replacing corn and soybeans (400 g/kg) in concentrate promoted a profit of US$0.07/animal per day. Licuri cake is indicated to concentrate the supplementation of dairy cows with average productions of 10 kg/day at levels up to 400 g/kg in the concentrate supplement because it provides an additional profit of US$0.07/animal per day and increased milk and Minas frescal cheese fat without negative effects on productive parameters.     

Daily copper supplement effects on copper balance in trained subjects during prolonged restriction of muscular activity

The aim of this study was to assess the effect of a daily intake of copper supplements on negative copper balance during prolonged exposure to hypokinesia (decreased number of kilometers per day). During hypokinesia (HK), negative copper balance is shown by increased, not by decreased, serum copper concentration, as it happens in other situations. Studies were done during a 30-d prehypokinetic period and a 364-d hypokinetic period. Forty male trained volunteers aged 22–26 yr with a peak oxygen uptake of 66.4 mL/min/kg and with an average of 13.7 km/d running distance were chosen as subjects. They were equally divided into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SACS and SHKS groups took 0.09 mg copper carbonate/kg body weight daily. The SHKS and UHKS groups were maintained under an average running distance of 1.7 km/d, whereas the SACS and UACS groups did not experience any modifications in their normal training routines. During the 30-d prehypokinetic period and the 346-d hypokinetic period, urinary excretion of copper, calcium, and magnesium and serum concentrations of copper, calcium, and magnesium were measured. Copper loss in feces and copper balance was also determined. In both UHKS and SHKS groups, urinary excretion of copper, calcium, and magnesium and concentrations of copper, magnesium, and calcium in serum increased significantly when compared with the SACS and UACS groups. Loss of copper in feces was also increased significantly in the SHKS and UHKS groups when compared with the UACS and SACS groups. Throughout the study, the copper balance was negative in the SHKS and UHKS groups, whereas in the SACS and UACS groups, the copper balance was positive. It was concluded that a daily intake of copper supplements cannot be used to prevent copper deficiency shown by increased copper concentration. Copper supplements also failed to prevent negative copper balance and copper losses in feces and urine in endurancetrained subjects during prolonged exposure to HK.     

The effect of concentrate allocation on traffic and milk production of pasture-based cows milked by an automatic milking system

Increased economic, societal and environmental challenges facing agriculture are leading to a greater focus on effective way to combine grazing and automatic milking systems (AMS). One of the fundamental aspects of robotic milking is cows’ traffic to the AMS. Numerous studies have identified feed provided, either as fresh grass or concentrate supplement, as the main incentive for cows to return to the robot. The aim of this study was to determine the effect of concentrate allocation on voluntary cow traffic from pasture to the robot during the grazing period, to highlight the interactions between grazed pasture and concentrate allocation in terms of substitution rate and the subsequent effect on average milk yield and composition. Thus, 29 grazing cows, milked by a mobile robot, were monitored for the grazing period (4 months). They were assigned to two groups: a low concentrate (LC) group (15 cows) and a high concentrate (HC) group (14 cows) receiving 2 and 4 kg concentrate/cow per day, respectively; two allocations per day of fresh pasture were provided at 0700 and 1600 h. The cows had to go through the AMS to receive the fresh pasture allocation. The effect of concentrate level on robot visitation was calculated by summing milkings, refusals and failed milkings/cow per day. The impact on average daily milk yield and composition was also determined. The interaction between lactation number and month was used as an indicator of pasture availability. Concentrate allocation increased significantly robot visitations in HC (3.60±0.07 visitations/cow per day in HC and 3.10±0.07 visitations/cow per day in LC; P<0.001) while milkings/cow per day were similar in both groups (LC: 2.37±0.02/day and HC: 2.39±0.02/day; Ns). The average daily milk yield over the grazing period was enhanced in HC (22.39±0.22 kg/cow per day in HC and 21.33±0.22 kg/cow per day in LC; P<0.001). However the gain in milk due to higher concentrate supply was limited with regards to the amount of provided concentrates. Milking frequency in HC primiparous compared with LC was increased. In the context of this study, considering high concentrate levels as an incentive for robot visitation might be questioned, as it had no impact on milking frequency and limited impact on average milk yield and composition. By contrast, increased concentrate supply could be targeted specifically to primiparous cows.     

Effect of daily concentrate intake at weaning on performance of Belgian Blue double-muscled rearing calves

Weaning at a different daily concentrate intake was investigated during a 140-d experimental period, using 54 male and 68 female newborn Belgian Blue double-muscled animals. They were divided into three comparable groups and received milk at 10% of their birth weight up to weaning. Concentrate was levelled off at a maximum daily intake of 3 kg, while grass hay was freely available. Weaning occurred at a daily concentrate intake level (CL) of 0.5, 0.75 and 1.0 kg, respectively. Weaning at an increased CL prolonged the milk-feeding period by 13.1 and 14.6 days, and resulted in a higher pre- and post-weaning growth rate (p < 0.05). Daily gain during the entire experimental period averaged 0.84, 0.85 and 0.88 kg for the respective groups (p = 0.065). Daily concentrate intake was not different among groups, with only a small effect of CL on intake around weaning. Early weaning resulted in a significant reduction of hay intake (p = 0.032). Total daily net energy intake increased slightly with a higher CL at weaning, so that energy conversion was slightly improved, amounting to 17.7, 17.6 and 17.4 MJ/kg gain, respectively. Energy balance during the first week after weaning was negative for CL 0.5 kg (-22%), while it was close to 0 for CL 0.75 kg (-2%) or positive for CL 1.0 kg. Most effects of CL at weaning were similar for males and females, but male calves tended to have a higher intake and a faster growth rate than females. It can be concluded that weaning should be delayed until Belgian Blue double-muscled calves consume at least 0.75 kg per day or more for reasons of welfare, although performance was hardly improved by weaning at a daily concentrate intake of more than 0.5 kg per day.     

Changes in the regulation of calcium metabolism and bone calcium content during growth in the absence of endogenous prolactin and during hyperprolactinemia: a longitudinal study in male and female Wistar rats

Since endogenous prolactin has been shown to enhance food consumption, calcium absorption, and bone calcium turnover in the pregnant rat, the role of endogenous prolactin in the regulation of calcium metabolism was investigated in 3-day balance studies of female Wistar rats from the age of 3 to 11 weeks. The study was divided into two parts. In part I, calcium metabolism in males and females was compared. In part II, 3-week old female rats were divided into 5 groups: (i) control animals receiving 0.9% NaCl; (ii) animals receiving 6 mg bromocriptine/kg/day (- PRLendo group); (iii) animals receiving 2.5 mg ovine prolactin/kg/day (+PRLexo); (iv) sham-operated animals receiving 0.9% NaCl, and (v) animals with two extra pituitaries implanted under the renal capsule, receiving 0.9% NaCl (AP group). Results showed that rapid growth occurred between 3 and 6 weeks with maximum fractional calcium absorption and calcium retention at 5 weeks of age in both sexes. The data also showed a physiological significance of endogenous prolactin in enhancing calcium absorption and retention in 5 week old rats. In an absence of prolactin, peak calcium absorption was delayed in 7-week old animals, and vertebral calcium content of 11-week old animals was reduced by 18%. Hyperprolactinemia in the AP group was found to enhance fractional calcium absorption and calcium retention at 7, 9, and 11 weeks and increased the femoral calcium content by 16%. It could be concluded that a physiological role of prolactin is the stimulation of calcium absorption and maintainance of bone calcium content during growth and development.     

Calcaemic responses in the yellow monitor, varanus flavescens to vitamin D3 administration

The effect of a daily intramuscular injection of vitamin D3 (2000 IU/100 g b.wt) on serum calcium level was investigated in Varanus flavescens. This treatment evoked hypercalcaemia on day 3 which progressed up to day 7. At day 14 a decline was noticed in the serum calcium level which was followed by a rise from day 21 to day 28.     

1 alpha-Hydroxyvitamin D2 is less toxic than 1 alpha-hydroxyvitamin D3 in the rat

An LD50 of 0.2 mg/kg body wt has been determined for 1 alpha-hydroxyvitamin D3 in the rat. In comparison, the LD50 for 1 alpha-hydroxyvitamin D2 is between 3.5 and 6.5 mg/kg. In terms of chronic toxicity, 1 alpha-hydroxyvitamin D3 at a dose of 5 micrograms/kg/day causes death of one-half the animals in a 4-week period. On the other hand, 20 micrograms/kg/day of 1 alpha-hydroxyvitamin D2 is required to induce similar toxicity. The body weight record and renal calcium accumulation during chronic treatment support the above conclusion. It therefore appears that 1 alpha-hydroxyvitamin D2 is between 5 and 15 times less toxic than 1 alpha-hydroxyvitamin D3. This surprising result prompted a reexamination of the relative biological activity of 1 alpha-hydroxyvitamin D2 and 1 alpha-hydroxyvitamin D3. Both compounds are equally potent in the stimulation of intestinal calcium transport, bone calcium mobilization, in the elevation of serum phosphorus, and in the healing of rickets in the rat. The reason for lower toxicity of 1 alpha-hydroxyvitamin D2 is unknown. The results suggest that 1 alpha-hydroxyvitamin D2 might represent a therapeutically superior compound.     

Investigations on the effect of a niacin supplementation to three diets differing in forage-to-concentrate ratio on several blood and milk variables of dairy cows

The objective of this study was to investigate the influence of a niacin supplementation to three diets with different forage-to-concentrate ratios on blood and milk parameters. Seven midlactation (102 ± 18 days in milk) and three dry cows of the Holstein-Friesian breed, equipped with cannulas in the dorsal sac of the rumen and proximal duodenum, were used. On a dry matter basis the rations applied consisted of either ? concentrate and ? forage (LC), ½ concentrate and ½ forage (MC), or ? concentrate and ? forage (HC). They were fed for one period without and in the following with a supplementation of 6 g niacin (nicotinic acid) per cow per day. The basal niacin content was 35.0 mg/kg for LC, 34.6 mg/kg for MC and 34.4 mg/kg for the HC diets on a dry matter basis. Blood was sampled before, then three and six hours after first morning feeding from the vena jugularis externa. Milk samples were obtained on two days. Niacin feeding enhanced concentrations of glucose and urea in serum (p < 0.05). No effect of supplemental niacin was seen on serum non-esterified fatty acids or ß-hydroxybutyrate concentrations. Increasing the proportion of concentrate and niacin supplementation enhanced serum nicotinamide concentration (p < 0.01). Nicotinamide concentrations or amounts excreted via milk were influenced by forage-to-concentrate ratio (p < 0.05), but not by niacin supplementation. Milk fat composition showed an effect of additional niacin, as the proportion of oleic acid increased in milk of niacin supplemented cows (p = 0.04). For all parameters analysed, no significant interaction between forage-to-concentrate ratio and niacin supplementation was found.     

Analysis of nutrient concentrations in the diet,serum, and urine of giraffe from surveyed North American zoological institutions

The objectives of the present research were to conduct a survey to investigate the health history and feeding practices of giraffe in captivity in North America and to obtain samples of hay, concentrate, browse, urine, and serum to compare across zoos, possible factors relating to the development of urolithiasis. Forty‐one out of 98 institutions contacted responded, representing 218 giraffe. All responding zoos fed concentrate and alfalfa hay was the primary forage. Sixty‐five percent of zoos fed browse and 43 different species of browse were listed. Six zoos reported a history of urolithiasis, seven reported wasting syndrome, and 10 reported sudden death. The median daily amount (as fed) of concentrate and hay offered were 5.45 kg (range of 2.73–9.55 kg) and 6.82 kg (range of 2.53–12.50 kg), respectively. The concentrate:hay ratio of the offered diet ranged from 0.22 to 3.47 with a median value of 0.79. Forty‐three percent of the institutions offered a ratio greater than 1:1. Samples of concentrate and hay (six zoos), serum (five zoos), and urine (seven zoos) were obtained for chemical analyses. Analyzed nutrient content of the consumed diet, measured by weighing feed and orts for three consecutive days, met recommendations for giraffe, but was excessive for crude protein and P. Concentrate:hay and serum P were positively correlated (r=0.72; P<0.05). High dietary P content and a high level of concentrate relative to hay may be contributing factors to urolith formation and warrant further investigation. Zoo Biol 29:457–469, 2010. © 2009 Wiley‐Liss, Inc.     

Prevention of processes coupled with free radical formation prevents also the development of calcium-resistance in the diabetic heart

Recently it was shown that besides their negative role in pathogenesis of diabetes, reactive oxygen species (ROS) and particularly the products of non-enzymatic glycation of proteins (NEGP) may also participate in some processes of adaptation of the myocardium to diabetes, such as in the mechanism of development of calcium resistance of the heart. Our study revealed that the hearts of rats with experimentally induced diabetes (single dose of streptozotocin, 45 mg/kg i.v., 6 U/kg insulin daily) develop considerable resistance against calcium overload (induced by means of Ca-paradox). On the day 63 after the beginning of experiment, when the diabetic cardiomyopathy became fully developed but the hearts were still not failing, their calcium resistance was increased to 83.33%. Our results provide evidence that, when applied in a special regimen, resorcylidene aminoguanidine (RAG, 4 mg/kg) prevented both, the formation of fructosamine (a source of ROS generation), and also that of the advanced Maillard products, in the heart sarcolemma of diabetic rats. The effect of RAG was accompanied by a decrease in calcium resistance in the group of rats with chronic diabetes (63 days) from 83.3 to 46.7%. It is concluded that NEGP and ROS formation are inevitably needed for development of calcium resistance in the diabetic hearts.     

Serum calcium level of freshwater snake, Natrix piscator, in response to vitamin D3 administration

The effect of i.m. injection of vitamin D3 (25 IU/100 g b.wt) on serum calcium level was investigated in Natrix piscator. This treatment evokes hypercalcemia at day 3 which progresses up to day 5. Thereafter, a decline was observed in the serum calcium level at day 10 and day 15.