Effect of daily movement of dairy cattle to fresh grass in morning or afternoon on intake, grazing behaviour, rumen fermentation and milk production

Twenty Holstein cows were split into two equal groups to test the effect of daily move to a previously ungrazed strip after morning milking (MA) or afternoon milking (AA) on herbage intake, grazing behaviour, rumen characteristics and milk production using a randomized block design with three periods of 14 days each. Milking took place at 06.00 and 16.00 h. The chemical composition of grass was similar between treatments, but an interaction between treatment and time of sampling was found in all variables except acid detergent lignin (ADL). The most pronounced differences existed in sugar content. Grass sugar content was greatest following afternoon milking. However, the difference in sugar content in grass was much larger in MA (158 v 114 g/kg dry matter (DM) at 16.00 and 06.00 h, respectively) than in AA (147 v 129 g/kg DM at 16.00 and 06.00 h, respectively). Neutral detergent fibre (NDF) was significantly higher at 06.00 h than at 16.00 h (469 v 425 g/kg DM) in AA, but was equal between morning and afternoon in MA (453 g/kg DM). Herbage intake, determined using the n-alkane technique, did not differ between treatments. Grazing behaviour observed using IGER graze recorders were similar between treatments, except for ruminating time, bite rate and the number of ruminations and boli per period of the day. However, interactions between treatment and time in grazing behaviour variables were found. Grazing time was longer and number of bites was greater following allocation to a new plot (after milking in the morning in MA or milking in the afternoon in AA) when compared to allocation to the same plot after the subsequent milking per treatment (after milking in the afternoon or morning in MA and AA, respectively). In comparison to AA, grazing time in MA was more evenly distributed during the day but lower during the night. The combined effects of differences in grazing behaviour and chemical composition of the grass between treatments in different periods of the day probably caused higher intake of sugars in AA, resulting in a significantly higher non-glucogenic to glucogenic volatile fatty acid ratio (NGR) in the rumen in AA than MA. Milk fat content was lower in MA than AA, but milk production and milk protein and lactose content did not differ. In conclusion, time of allocation to a fresh plot altered the distribution of grazing behaviour variables over the day, and affected NGR and milk fat content, but herbage intake and milk production were not change

Start-up inertia as an origin for heterogeneous flow

For quite some time non-monotonic flow curve was thought to be a requirement for shear banded flows in complex fluids. Thus, in simple yield stress fluids shear banding was considered to be absent. Recent spatially resolved rheological experiments have found simple yield stress fluids to exhibit shear banded flow profiles. One proposed mechanism for the initiation of such transient shear banding process has been a small stress heterogeneity rising from the experimental device geometry. Here, using Computational Fluid Dynamics methods, we show that transient shear banding can be initialized even under homogeneous stress conditions by the fluid start-up inertia, and that such mechanism indeed is present in realistic experimental conditions

Required Evidence for Clinical Applications of Liquid Biopsy Using Especially CTCs in Lung Cancer

As therapies have become more and more dependent on tumor as well as patient characteristics, obtaining tumor material has become of great importance. Liquid biopsies hold much potential as shown by a large amount of evidence across several studies. Clinical applications for circulating tumor cells (CTCs) are unfortunately still lacking. In part this is due to a lack of studies comparing liquid biopsies to conventional diagnostics and response measurements as well as studies showing that liquid biopsies can be used to switch therapies leading to improved outcomes. However, liquid biopsies using ctDNA for specific markers such as EGFR, ALK, ROS1 or RET have clinical applications because specific drugs are available

Meer melk bij vaker omweiden

Tijdens weidegang is voldoende voeropname essentieel voor hoge melkproducties. Vaker omweiden zorgt voor een hogere voeropname, maar alleen bij voldoende gewashoogte, zo blijkt uit een promotiestudie van Wageningen Universiteit. Het effect van ’s avonds in plaats van ’s ochtends inscharen is beperk

The Meal Criterion Estimated in Grazing Dairy Cattle: Evaluation of Different Methods

The meal criterion (MC) has been found a useful tool to pre-treat intake behaviour data in dairy cows. It was defined as the longest interval between bouts that belong to the same meal (Tolkamp & Kyriazakis, 1999), necessary to cluster bouts to meals. The method of Yeates et al. (2001) calculating the loge-transformed intervals between bouts and using the Gaussian-Gaussian-Weibull (GGW) model to calculate the MC was found to provide the best estimation of the MC in biological as well as statistical terms. However, in grazing dairy cattle the MC-estimation has only been carried out by Rook & Huckle (1997) using a broken stick method. The aim of this study was to estimate the MC in grazing dairy cattle with the recently developed estimation methods

Effect of Perennial Ryegrass Cultivars on the Fatty Acid Composition in Milk of Stall-Fed Cows

Herbage provides bulk feed for ruminants and plant lipids, especially C18:3, are a major source of benefical fatty acids (FA) in milk. There are very few direct comparisons allowing a precise evaluation of the effects of the basal forage diet on milk FA composition. Grass quality differences can affect rumen metabolism and there could be opportunities to change the composition of ruminant products through choice of grass cultivar. To test this hypothesis, six cultivars were fed to dairy cows in a stall-feeding trial with fresh grass to evaluate the effect of grass cultivar on rumen VFA and milk FA composition during the growing season

Modelling Animal Systems Paper: Update of the Dutch protein evaluation system for ruminants: the DVE/OEB2010 system

In the current Dutch protein evaluation system (the DVE/OEB1991 system), two characteristics are calculated for each feed: true protein digested in the intestine (DVE) and the rumen degradable protein balance (OEB). Of these, DVE represents the protein value of a feed, while OEB is the difference between the potential microbial protein synthesis (MPS) on the basis of available rumen degradable protein and that on the basis of available rumen degradable energy. DVE can be separated into three components: (i) feed crude protein undegraded in the rumen but digested in the small intestine, (ii) microbial true protein synthesized in the rumen and digested in the small intestine, and (iii) endogenous protein lost in the digestive processes. Based on new research findings, the DVE/OEB1991 system has recently been updated to the DVE/OEB2010 system. More detail and differentiation is included concerning the representation of chemical components in feed, the rumen degradation characteristics of these components, the efficiency of MPS and the fractional passage rates. For each chemical component, the soluble, washout, potentially degradable and truly non-degradable fractions are defined with separate fractional degradation rates. Similarly, fractional passage rates for each of these fractions were identified and partly expressed as a function of fractional degradation rate. Efficiency of MPS is related to the various fractions of the chemical components and their associated fractional passage rates. Only minor changes were made with respect to the amount of DVE required for maintenance and production purposes of the animal. Differences from other current protein evaluation systems, viz. the Cornell Net Carbohydrate and Protein system and the Feed into Milk system, are discussed