Wilfried van Straalen

Schothorst Feed Research · Ruminant Research

Nine Holstein dairy cows were fed diets with increasing proportions of rapidly fermentable carbohydrates (RFCH) to investigate the effect on reticular pH, milk fat content (MFC), 18-carbon fatty acid proportions in blood plasma and milk, and bacterial community in buccal swab samples. Inter-animal variation was expected in terms of reticular pH res...

The current study was carried out to assess 2 hypotheses: (1) cows differ in susceptibility to a subacute ruminal acidosis (SARA) challenge, and (2) the milk fatty acid (FA) pattern can be used to differentiate susceptible from nonsusceptible cows. For this, 2 consecutive experiments were performed. During experiment 1, the milk FA pattern was dete...

In modern protein evaluation systems the protein unit (PU) of a feedstuff and the requirement of PU is expressed as true protein assumed to be absorbed from the small intestine. Total PU supply originates from feed protein escaping rumen degradation and from microbial protein synthesised in the rumen. Escape feed PU is calculated from crude protein...

Two experiments with rumen-fistulated dairy cows were conducted to evaluate the effects of feeding docosahexaenoic acid (DHA; C22:6 n-3)-enriched diets or diets provoking a decreased rumen pH on milk fatty acid composition. In the first experiment, dietary treatments were tested during 21-d experimental periods in a 4 x 4 Latin square design. Diets...

Increasing the availability of glucogenic nutrients relative to lipogenic nutrients has been hypothesized to decrease the production of milk fat, to improve the energy balance (EB), and to decrease the incidence and severity of metabolic and reproductive disorders in dairy cows in early lactation. Therefore, our objective was to evaluate the effect...

Metabolic problems related to negative energy balance suggest a role for the balance in supply of lipogenic and glucogenic nutrients. To test the effect of lipogenic and glucogenic nutrients on energy partitioning, energy balance and nitrogen balance of 16 lactating dairy cows were determined by indirect calorimetry in climate respiration chambers...

Two ring tests with five and three laboratories, respectively, were conducted to quantify variation within and among laboratories in an automated gas production technique. Single batches of the feeds soya bean meal (SBM), wheat grain (WG), grass silage (GS) and maize gluten meal (MG) were divided among the participating laboratories. Gas production...

Low energy balance increases the incidence of disease and contributes to poor reproductive performance. Monensin (an ionophore) increases energy precursors in the rumen. Monensin-treated cows had higher milk yield and lower serum ketone bodies, and thus better energy status, than control cows. This study aimed to validate a previously developed mod...

This study used a previously developed model to predict herd mean energy balance of the first 12 wk of lactation from test-day information. The predictions were compared with calculated energy balance based on feed analysis and to changes in body weight. Seven independent feeding trials including 43 diets (519 lactations, 254 cows; 1987 to 1996) we...

This study was conducted to (1) predict herd mean EB, and (2) investigate whether herd size affects the precision of prediction. In order to achieve the first goal, it was studied to what extent milk test day information, body condition scores, and blood and milk ketones can estimate energy balance at cow level. EB was calculated in 72 Holstein–Fre...

In situ incubations were carried out to investigate the effect of rate of nitrogen fertilization and season on rumen degradation of ryegrass. Samples of Lolium perenne of grazed herbage, fertilized at two levels of nitrogen (250 and 550 kg N/ha/year), were collected in May, July-August, September and October, and incubated in nylon bags in the rume...

The disappearance of total N, non-protein-N and amino acid-N after washing, rumen incubation and intestinal passage of sugarbeet pulp, maize-gluten feed, maize feed meal, palm kernel meal, soyabean hulls, soyabean meal, grass silage, maize silage and concentrate was measured in four dairy cows using nylon-bag techniques. Disappearance of amino acid...

In the Netherlands, the dairy husbandry is held responsible for a major part of the N-pollution of the environment. The objective of this thesis was to develop a model that predicts N flow in the animal and N excretion in faeces, urine and milk in order to reduce unnecessary N losses. The model was based on the concepts of modern protein evaluation...

A study was carried out to investigate which factors account for the variation in efficiency of milk protein production and to estimate the DVE-requirement for milkprotein production, To achieve the first goal, regression analysis was used on data from 29 production experiments with dairy cows. The efficiency was not constant and 91% of the variati...

A comparison was made of the effect of season and maturity on the in situ ruminal breakdown and intestinal protein digestion in dairy cows between intensively N-fertilized grass (whole sward) and moderately N-fertilized ryegrass and clover from a mixed sward. From May to September 1990, eight consecutive cuts were made, representing alternate harve...

In 1991 a new protein evaluation system replaced the Digestible Crude Protein (DCP) system in the Netherlands: the DVE/OEB-system. The system was mainly developed with the aim to prevent avoidable losses of nitrogen, by feeding according to more exactly defined requirements of dairy cows. A second aim was to predict milk protein production more acc...

Protein evaluation systems (crude protein (CP), digestible crude protein (DCP), protein digested in the intestine (PDI), amino acids truly absorbed in the small intestine (AAT), absorbed protein (AP), metabolizable protein (MP), crude protein flow at the duodenum (AAS) and digestible protein in intestine (DVE)) were validated using data from 15 pro...

Bij deze voederproef was de vraag of met een vergaande energiebeperking de ram- en ooilammeren op resp. 36 en 40 kg afgeleverd kunnen worden met een 2°-vetbedekking.

In een voederproef werd de invloed van het niveau en de duur van een energiebeperking op de groei, voederconversie en slachtkwaliteit onderzocht.

Ruminal, intestinal, and total tract digestibilities of CP in grass, grass silage, and clover were measured using the mobile nylon bag method. Total tract indigestibilities measured with this method were compared with indigestible CP predicted by in vitro, 14-d ruminal incubation, and 12-h followed by 14-d ruminal incubation methods. Indigestible C...

Growth performance of calves was estimated by means of heart girth measurements on 48 farms during winter housing (from December to the end of March). Level of exposure to nematode infection was measured by antibody titres, pepsinogen values, and faecal examinations. Half of each herd was treated with albendazole after housing. All infection parame...

Liveweight of calves on 89 dairy farms was measured at the end of the grazing season and related per herd to the level of exposure to nematode infection during the grazing season. There were significant between-herd variations in antibody titres against Ostertagia spp., Cooperia spp. and Dictyocaulus viviparus as well as in pepsinogen values. All b...

Liveweight of calves on 86 dairy farms was measured at the end of the grazing season and related per herd to the level of exposure to nematode infection estimated in October and December. There were significant between-herd variations in all the serological infection parameters measured. On average 20.5 larvae per gram faeces (geometric mean) were...