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

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

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

The influence of the method of preservation of forages on the digestion in dairy cows. 2. Digestion of organic matter, energy and amino acids in forestomachs and intestines.

2. Two dairy cows with duodenal reentrant and rumen cannulae were given diets containing artificially dried and pelleted grass (GP), grass silage treated with formic acid (GSF), grass silage treated with a mixture of formic acid and formaldehyde (GSFF) or grass silage without additive (GS). DM intake was 14.8 to 16.0 kg/day and about 30% of the N in the diets was from grass pellets or silages. Between 45 and 57% of the apparently digested organic matter and between 26 and 41% of the apparently digested energy disappeared before the intestines. The higher values were found with GSF and GS.Total amino acid N reaching the duodenum was between 104 and 134% of intake, highest with GP and GSFF. The amounts of individual amino acids reaching the small intestine were from 75 to 270% of the amounts ingested. High values (>150%) were found for glycine, lysine, methionine and tyrosine; low values

Effect of the roughage/concentrate ratio on nitrogen entering the small intestine of dairy cows.

The effect of different roughage:concentrate ratios on N entering the small intestine was studied in groups of 2 to 5 cows with a rumen fistula and re-entrant cannulae at the beginning of the small intestine. In 3 series there were 10 treatments in which DM intake ranged between 3.8 and 15.7 kg daily; the proportion of long roughage in the diet was from 29 to 81%. The apparent digestibility of organic matter (O), crude fibre (XF) and nitrogen-free extracts (XX) was 76, 69 and 81%, respectively. The proportion of the digestion taking place in the stomach was 59, 94 and 76%. A larger proportion of the apparently digestible organic matter tended to be digested in the stomach when there was a larger proportion of long roughage in the diet. The contribution of microbial N to the intestinal N was estimated. From this the efficiency of microbial protein synthesis was estimated and related to the amount of carbohydrates (XF + XX) fermented in the stomach. Per kg carbohydrates fermented, 32 plus or minus 1.5 g microbial N was produced. The percentage of dietary N not degraded in the stomach averaged 30 plus or minus 1.5. Varying the ratio between long roughage and pelleted concentrates seemed to have little effect on the degradation of dietary protein or on the efficiency of microbial protein synthesis. With long roughage in the diet between 29 and 81% there seems little effect of varying the roughage:concentrate ratio on the protein supply in dairy cows. (Abstract retrieved from CAB Abstracts by CABI’s permission

Actualisatie excretiecijfers landbouwhuisdieren voor forfaits regeling Meststoffenwet

LNV heeft de Commissie van Deskundigen Meststoffenwet (CDM) gevraagd voor de diercategorieën uit de meststoffenwet de excretiecijfers te valideren en zo nodig te actualiseren. De hiervoor in het leven geroepen werkgroep heeft de forfaits uit de meststoffenwet kritisch vergeleken met de excretiecijfers uit recente rapporten (o.a. CBS) en met de gemiddelde excretiecijfers zoals die met de nu beschikbare informatie worden berekend. De door de CDM verwachte gemiddelde excretie van N en P door melkkoeien in de periode 2006-2009 is hoger dan de in de praktijk gerealiseerde gemiddelde excretie, voornamelijk doordat bij de vaststelling van de verwachte excretie met een geringer aandeel snijmaïs in het rantsoen rekening is gehouden dan in de praktijk nu wordt gerealiseer