Relative Bioavailability of Niacin Supplements for Dairy Cows: Effects of Rumen Protection and of Feed Processing

The present study aimed to examine the effective systemic bioavailability of niacin— with particular focus on its galenic form—and feed processing. Experiment 1 was conducted with 35 dairy cows to investigate the effects of various doses of oral supplemented nicotinic acid (NA) either in differing galenic forms (non-rumen protected (nRP) vs. rumen protected form (RP)) on serum niacin concentrations. Experiment 2 was designed as a pharmacokinetic study examining the serum niacin kinetics over 24 h after giving a single oral bolus of 24 g nRP or RP NA admixed in either pelleted or ground concentrate. In both experiments, only the niacin vitamer nicotinamide (NAM) was detected. Results of experiment 1 showed that both galenic forms at a dose of 24 g/cow daily elevated NAM concentrations at the beginning of the experiment. Despite a daily supplementation, NAM concentrations decreased continuously towards the end of the experiment which was more steeply in nRP NA (p = 0.03). On experimental day 21, NAM concentrations were higher when feeding RP NA (p = 0.03) and the highest dose (24 g/day and cow) (p < 0.01). Results of experiment 2 indicated that nRP and RP were characterized by similar pharmacokinetic profiles resulting in similar areas under the curves as a net result of the kinetic counterbalancing alterations. Pelleting seemed not to influence the relative bioavailability

Suitability of n-alkanes and chromium (III) oxide as digestibility markers in calves at the end of the milk feeding period supplemented with a prebiotic

Prebiotics reveal positive effects on the growth performance of pigs and poultry, and might influence intestinal microflora. This, in consequence, could alter recovery rates of digestibility markers. In the current study, we evaluated the suitability of chromium (III) oxide (Cr2O3) and the synthetic alkanes n-dotriacontane (C32) and n-hexatriacontane (C36) as external markers for digestibility estimation compared with the standard total collection method in calves supplemented with galacto-oligosaccharides. Eight male German Holstein calves (average age ± SD = 57 ± 8 days) were divided into 2 milk replacer feeding groups (group receiving galacto-oligosaccharides [A] and control group [B]). Each of 2 groups of 4 individually fed calves received a distinct milk replacer with added markers for 14 days. They were fed twice daily restrictively with milk replacer, concentrate and hay. After an adaptation period of 10 days, total faeces were collected. Faecal marker recoveries (FMR, means ± SD) for C32 were (72 ± 14)% for A and (80 ± 12)% for B. Faecal marker recoveries for C36 was (82 ± 15)% and (88 ± 13)% for groups A and B, respectively. The FMR for Cr2O3 was (102 ± 11)% and (100 ± 1)% for groups A and B, respectively. There were no significant differences between total collection organic matter digestibility and marker based organic matter digestibility when using Cr2O3 and C36. But, when utilizing C32 to calculate nutrient digestibilities, results differed from the total collection method for organic matter, crude protein and ether extract. The results indicate that Cr2O3 and C36 can be applied in digestibility studies with calves and give accurate estimates for OM and nutrient digestibilities without correction for FMR. Keywords: Calves, Marker, Digestibility, Alkanes, Cr2O3, Galacto-oligosaccharide

Effects of Feed Particle Size and Hydro-Thermal Processing Methods on Starch Modification, Nutrient Digestibility and the Performance and the Gastrointestinal Tract of Broilers

Influences of feed particle size (coarse, fine) and hydro-thermal processing methods (HTPM) (without−non-compacted feed, pelleting, expanding and pelleting) on feeding value and the performance and digestive tract of 624 broilers were studied. HTPM increased the starch disintegration of feed. Starch disintegration and electron microscopy indicated the highest degree of starch modification in expanded and pelleted feed. HTPM affected ether extract digestibility (p < 0.05). A grinding-by-HTPM interaction was found in case of crude protein digestibility (p = 0.008). Non-compacted feed reduced daily feed intake (DFI) and body weight gain and increased the feed to gain ratio compared to compacted feeds (p < 0.001). Compacted feeds increased proventricular size and the risk of Isthmus gastrici dilatation compared to coarsely ground non-compacted feed, except for finely ground expanded and pelleted feed. Finely ground feed reduced proventricular weights compared to coarsely ground feed and pelleted feed compared to other feeds. Non-compacted feed increased gizzard weights compared to compacted feeds. Relationships between proventricular size and Isthmus gastrici dilatation and the DFI were detected. Summarizing, the beneficial effects of pelleted feed were mainly based on the reduction of feed wastage and selection. However, the high DFI caused by pellet feeding is also a main risk factor for proventricular dilatation

Free-air CO2 enrichment modifies maize quality only under drought stress

International audienceClimate scenarios show that atmospheric CO2 concentrations will continue to increase. As a consequence, more frequent and severe drought periods are expected. Drought will thus modify plant growth. Although maize is a major crop globally, little information is available on how atmospheric and climatic changes will change maize quality. Here, in a field experiment, maize was grown in 2007 and 2008 under ambient (380 ppm) and elevated CO2 (550 ppm) using free-air CO2 enrichment. In 2007, maize was grown under well-watered conditions only. In 2008, we applied a drought stress treatment in which the plants received only half the amount of water of the well-watered treatment. We measured the concentrations of minerals and quality-related traits in aboveground biomass and kernels at the end of each growing season. Results show first the absence of effect of elevated CO2 under well-watered conditions. By contrast, drought stress modified several traits and interactions under elevated CO2. These results support the hypothesis that the C4 plant maize does not react to an increase in atmospheric CO2 as long as no drought stress is prominent. This finding contrasts with the impact of elevated CO2 on C3 plants. Several drought stress effects found in our study will have important implications for food and feed use. However, the effects of drought stress on the traits were less pronounced under elevated CO2 than under ambient CO2 level. Hence, an elevated CO2 concentration mitigates the drought stress impacts on elemental composition and quality traits of maize

Effects of Prepartum Dietary Energy Level and Nicotinic Acid Supplementation on Immunological, Hematological and Biochemical Parameters of Periparturient Dairy Cows Differing in Parity

The periparturient period is critical according to health, productivity and profitability. As this period is fundamental for the success of the lactation period, the interest in improving periparturient health by dietary supplements increased in recent years. The present study investigated the effects of feeding nicotinic acid (NA) combined with varying dietary energy densities on immunological, hematological and biochemical parameters of periparturient cows differing in parity. Thirty-six multiparous and 20 primiparous dairy cows were enrolled in the study 42 days before expected parturition date until 100 days postpartum with the half of the cows being supplemented with 24 g of NA/d. After parturition a diet with 30% concentrate was fed to all cows which was followed by different concentrate escalation strategies. Dietary NA supplementation was ceased on day 24 postpartum. Dietary NA increased (P = 0.010) serum nicotinamide concentrations (mean of 3.35 ± 1.65 µg/mL), whereas NA could not be detected. Present data emphasize that periparturient cows are faced with major physiological challenges and that both parity-groups have different prerequisites to adapt to those changes irrespective of NA supplementation. The overfeeding of energy to cows which were similar in body condition score had only minor effects on periparturient immune system function and the metabolism of those cows

Effects of a Change from an Indoor-Based Total Mixed Ration to a Rotational Pasture System Combined with a Moderate Concentrate Feed Supply on Immunological Cell and Blood Parameters of Dairy Cows

In spring, transition from a total mixed ration (TMR) to a full grazing ration with moderate concentrate supply influences cow’s metabolism. It has been shown that feeding moderate amounts of concentrate during fulltime grazing did not prevent energy shortage and lipomobilization, alterations in energy metabolism, decreasing milk production and loss in body weight. As diet change and energy balance are closely related to immune reactivity, in this trial the effect of transition to pasture on specific immune parameters of cows was documented. Over a 12-week trial 43 dairy cows were observed during transition from confinement to pasture (PG; n = 22) and compared to cows fed TMR indoor (CG; n = 21). The CG stayed on a TMR based ration (35% corn silage, 35% grass silage, 30% concentrate; dry matter (DM) basis), whereas the PG slowly switched to a pasture -based ration (week 0 and 1 = TMR, week 2 = TMR and 3 h pasture·day−1, week 3 and 4 = TMR and 12 h pasture·day−1, and week 5 to 11 = pasture combined with 4.5 kg DM concentrate·cow−1·day−1). Inflammatory markers like blood haptoglobin or tryptophan to kynurenine ratio did not indicate acute phase reaction. Proportions of CD4+ (T-helper cells) and CD8+ cells (cytotoxic T-cells) remained uninfluenced as well. White blood cell concentration and its subpopulation of granulocytes increased over time in the PG. Stimulation ability of peripheral blood mononuclear cells to mount an oxidative burst significantly increased during the trial, too. The endogenous antioxidant state as characterized by glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity in blood of the PG did not change, whereas the vitamin E concentration reached the highest level at the end of the trial. The 25-CHO metabolites of vitamin D increased as soon as the PG had pasture access, whereas the other metabolite 25-ERG decreased. The results of this study indicate that transition to pasture affects immune related parameters. However, the consequences of the observed effects on health status of the pasture group need to be clarified in further studies with a defined concurrent immune challenge

Effects of a Change from an Indoor-Based Total Mixed Ration to a Rotational Pasture System Combined With a Moderate Concentrate Feed Supply on Rumen Fermentation of Dairy Cows

In spring, transition from a total mixed ration (TMR) to pasture requires rumen adaptions for the cow. It had been shown that transition period does not necessarily mean an increased risk for subacute ruminal acidosis (SARA). After adaption to pasture, however, supplying low amounts of concentrate did indicate increased risk, but caused no adverse effects on rumen morphology and absorption capacity. The present study aimed to investigate the effect of transition, and how a supply of 4.5 kg dry matter concentrate·cow−1 · day−1 during fulltime grazing influenced different rumen parameters. During a 12-week trial eleven rumen-cannulated dairy cows were observed during transition from confinement to pasture (PG; n = 6) and compared to cows fed TMR indoors (CG; n = 5). The CG stayed on a TMR based ration (35% corn silage, 35% grass silage, 30% concentrate; dry matter basis), whereas the PG slowly switched to a pasture-based ration (week 0 and 1 = TMR, week 2 = TMR and 3 h pasture·day−1, week 3 and 4 = TMR and 12 h pasture·day−1, and week 5 to 11 = pasture combined with 4.5 kg DM concentrate · cow−1·day−1). Papillae surface area decreased during transition and increased again during fulltime grazing, while the fractional absorption rate of volatile fatty acids (VFA) was not influenced. This suggests only a limited effect of papillae surface area on VFA absorption rate. Feeding changes resulted in different fermentation profiles of VFA. Changing ratio of starch to sugar during transition to fulltime grazing plus concentrate supply did not lead to lower rumen pH. In conclusion, the concentrate supply combined with high fermentable grass during fulltime grazing increased papillae surface area but did not affect absorption rate or rumen pH, so that risk for SARA was not increased

Effects of Different Concentrate Feed Proportions on Ruminal Ph Parameters, Duodenal Nutrient Flows and Efficiency of Microbial Crude Protein Synthesis in Dairy Cows During Early Lactation

The aim of the study was to examine different pH parameters, such as variations throughout the day, depending on differing concentrate feed proportions. Moreover, special attention was payed to individual variation in microbial efficiencies (microbial crude protein/fermented organic matter) and their relation to ruminal pH, nutrient flows and digestibilities. For this, cows were grouped according to microbial efficiency (more, n = 5, vs. less efficient cows, n = 4). After calving, thirteen ruminally cannulated pluriparous cows, including nine duodenally cannulated animals, were divided into groups offered rations with a lower (35% on dry matter basis, n = 7) or a higher (60% on dry matter basis, n = 6) concentrate feed proportion. Ruminal pH parameters were assessed continuously by using intraruminal probes. Nutrient flows, nutrient digestibility and microbial efficiency were determined for duodenally cannulated cows. For most ruminal pH parameters it seemed that individual variability was higher than the treatment effect. However, a positive relationship between actual concentrate intake and diurnal pH fluctuations was found. Besides, the effect of individually different microbial efficiencies was assessed. Again, there were no group differences for pH parameters. However, nutrient flows were significantly higher in more efficient cows, whereas digestibilities were lower in in more efficient cows

Effects of different concentrate fееd proportions on ruminal Ph parameters, duodenal nutrient flows and efficiency of Microbial Crude Protein Synthesis in Dairy Cows During early lactation

The aim of the study was to examine different pH parameters, such as variations throughout the day, depending on differing concentrate feed proportions. Moreover, special attention was payed to individual variation in microbial efficiencies (microbial crude protein/fermented organic matter) and their relation to ruminal pH, nutrient flows and digestibilities. For this, cows were grouped according to microbial efficiency (more, n = 5, vs. less efficient cows, n = 4). After calving, thirteen ruminally cannulated pluriparous cows, including nine duodenally cannulated animals, were divided into groups offered rations with a lower (35% on dry matter basis, n = 7) or a higher (60% on dry matter basis, n = 6) concentrate feed proportion. Ruminal pH parameters were assessed continuously by using intraruminal probes. Nutrient flows, nutrient digestibility and microbial efficiency were determined for duodenally cannulated cows. For most ruminal pH parameters it seemed that individual variability was higher than the treatment effect. However, a positive relationship between actual concentrate intake and diurnal pH fluctuations was found. Besides, the effect of individually different microbial efficiencies was assessed. Again, there were no group differences for pH parameters. However, nutrient flows were significantly higher in more efficient cows, whereas digestibilities were lower in in more efficient cows

Effects of a Change from an Indoor-Based Total Mixed Ration to a Rotational Pasture System Combined with a Moderate Concentrate Feed Supply on the Health and Performance of Dairy Cows

In spring, the transition from a total mixed ration (TMR) to pasture requires metabolic adaptions for the cow. It had been shown that supply of low amounts of concentrate after transition to full-time grazing caused energy deficits, resulting in a lower milking performance and changes in a variety of variables indicative for energy metabolism. The present study aimed to investigate how a moderate concentrate supply (4.5 kg dry matter cow/day) after transition to pasture influences health and production indicators. Over a 12-week trial period dairy cows were observed during transition from confinement to pasture (pasture group: PG) and compared to cows fed TMR indoors (confinement group: CG). On average, the PG consumed less feed and energy than the CG and mobilized body reserves, which is mirrored in a decrease of body condition and various fat depots. These effects were paralleled by elevated serum concentrations of non-esterified fatty acids and ketone bodies as well as an increase in liver fat content. The physical activity (elevated walking, eating, decreasing rumination time) of the PG was significantly higher than that of the CG, which intensified the energy deficiency and resulted in a lower milk yield. In conclusion, the moderate concentrate supply was insufficient to counterbalance the lower energy intake from pasture during transition