Force-directed design of a voluntary closing hand prosthesis.

This paper presents the design of a body-powered voluntary closing prosthetic hand. It is argued that the movement of the fingers before establishing a grip is much less relevant for good control of the object held than the distribution of forces once the object has been contacted. Based on this notion, the configurations of forces on the fingers and the force transmission through the whole mechanism were taken as a point of departure for the design, rather than movement characteristics. For a good distribution of pinching forces on the object and a natural behavior, the prosthesis is made adaptive and flexible. To achieve good force feedback, the disturbing influences of the cosmetic glove are strongly reduced by a compensation mechanism. To further improve the transmission of forces, friction is reduced by furnishing the whole mechanism with rolling links. This force-directed design approach has led to a simple mechanism with low operating force and good feedback of the pinching force.

Starch supplementation of grass harvested at two stages of maturity prior to ensiling: intake, digestion, and degradability by dairy cows.

The effects of the maturity of grass prior to ensiling and the supplementation of starch to grass silage on apparent digestibility, degradability, rumen content, and feed intake by dairy cows were investigated using a Latin square design. Treatments were silages from early or late cut grass with or without 4 kg of supplemental flaked corn starch. The silage from early cut grass contained more N and sugars than did the silage from late cut grass but was lower in neutral detergent fiber (NDF). Degradation characteristics were not different between the two silages. Apparent digestibilities of dry matter (DM), organic matter (OM), and N in the silage from late cut grass were lower than those in the silage from early cut grass, but NDF digestibility was not affected. Starch supplementation increased the lag phase for DM and OM in both silages, but the rate of degradation was decreased for NDF. Starch supplementation did not influence digestibilities of DM and OM in silage from early cut grass but decreased the digestibilities of DM and OM in silage from late cut grass. Crude protein and NDF digestibilities were decreased for silages from early and late cut grass. Starch supplementation increased NDF in the rumen of cows fed the silage from early cut grass, but NDF was not affected by starch supplementation for cows fed the silage from late cut grass. Rumen-degradable starch negatively influences degradability and apparent OM digestibility; the extent of the decrease is related to the maturity of the NDF.

Influence of maturity of grass silage and flaked corn starch on the production and metabolism of volatile fatty acids in dairy cows.

An experiment employing a Latin square design was used to quantify the effects of two stages of maturity of grass silage (early cut and late cut) and three concentrations of flaked corn starch (0, 2, and 4 kg) on the molar proportion of rumen volatile fatty acids (VFA), the production of rumen VFA, and the net fluxes of VFA in the splanchnic tissue of cows. The molar proportions of VFA in rumen fluid were similar for cows fed both silages. When the silage diets were supplemented with starch, the proportion of propionic acid increased for cows fed diets containing early cut grass silage, but no effects were found for cows fed diets containing late cut grass silage. Estimated gastrointestinal production of acetate, propionate, butyrate, and branched-chain fatty acids plus valerate was related to intake of metabolizable energy and organic matter fermented into VFA. The portal release of acetate was approximately 14% lower than the estimated production of acetate by cows fed diets containing early cut grass silage, but cows fed diets containing late cut grass silage showed a variable difference between estimated production and portal release (31, 24, and 15%, respectively) as starch supplementation increased. The portal release of butyrate plus beta-hydroxybutyrate and the release of branched-chain fatty acids plus valerate were approximately 70 and 25%, respectively, of the estimated gastrointestinal production. Propionate production was similar to the portal release of propionate. Net flux measurements in splanchnic tissue in combination with gastrointestinal digestion and kinetics provide information that increases the knowledge of pathways and metabolism and quantifies the availability of individual nutrients for milk production in dairy cows.

Effects of source of starch on net portal flux of glucose, lactate, volatile fatty acids and amino acids in the pig.

The ileal digestibilities of maize starch and native pea starch do not differ. However maize starch is digested faster than pea starch and the ileal amino acid digestibility of a diet containing pea starch is lower. In the present study, the net portal fluxes of glucose, lactate, volatile fatty acids (VFA) and amino acids were measured for diets including 650 g maize starch or pea starch/kg. The diets were fed at a level 870 kJ digestible energy/kg0.75 twice daily (06.00 and 18.00 hours) to four female pigs in a crossover design. Portal vein blood flow did not differ between maize and pea starches (1620 and 1484 ml/min respectively; SED 100; P = 0.23). For maize starch portal glucose flux was significantly higher during the first 6 h after feeding, was not different 8 h after feeding and was significantly lower thereafter. Net portal glucose flux was higher for maize starch than for pea starch (1759 and 1265 mmol/12 h respectively; SED 182; P = 0.054). Net portal lactate flux was not significantly different between maize and pea starches (36.5 and 67.2 mmol/12 h respectively; SED 24.1; P = 0.27) and net portal VFA flux was lower for maize starch than for pea starch (169 and 218 mmol/12 h respectively; SED 18; P = 0.054). Net portal fluxes of valine, isoleucine, phenylalanine, tryptophan, arginine, serine, cystine, tyrosine, lysine, histidine and the sum of essential amino acids tended to be or were higher (P < 0.1 or P < 0.05) and net portal flux of aspartic acid tended to be lower for pea starch (P < 0.1). It can be concluded that, although ileal digestibility of both starches is equal, the rate of appearance of glucose in the portal vein was higher for maize starch, influencing the net portal flux of amino acids.

Effect of resistant starch on net portal-drained viscera flux of glucose, volatile fatty acids, urea, and ammonia in growing pigs.

Net portal-drained viscera (PDV) flux of glucose, VFA, ammonia, and urea was determined in pigs fed diets with or without resistant starch. Diets consisted of 65% cornstarch (diet CS), 32.5% cornstarch and 32.5% raw potato starch (diet CPS), or 65% raw potato starch (diet PS); the remaining 35% supplied all amino acids, fat, fiber, minerals, and vitamins. The diets contained twice the maintenance requirement for energy and were fed twice daily to four barrows (initial BW 56 kg) in three periods in a crossover design. The pigs were fitted with catheters in a mesenteric vein, a mesenteric-artery, and the portal vein, and net PDV flux was calculated by multiplying portal-arterial concentration differences and corresponding portal vein flow. Net PDV flux of glucose was significantly less after feeding diets CPS and PS, and portal absorption of ileally digested glucose was 89, 66, and 41% for diets CS, CPS, and PS, respectively. Net PDV flux of VFA was lowest after feeding diet CS and three to four times higher after feeding diets CPS and PS. Net PDV flux of ammonia was highest for diet CS and almost halved after feeding diets CPS and PS. There was a small negative net PDV flux of urea for diets CS and CPS, which significantly increased after feeding diet PS. These results suggest that excretion of nitrogen is shifted from urine to feces primarily by reduction of the net PDV flux of ammonia when resistant starch is fed.

[Dynamics of calcium metabolism in lactating cows when the calcium content of the rations is reduced (author's transl)]. / Dynamiek van de ca-stofwisseling van melkgevende koeien bij een verlaagd ca-aanbod uit het voer

From twenty-eight balance trials and supplementary findings on the state of health, milk production, body weight and composition of the bone, blood, saliva, milk, urine and faeces it is concluded that four cows of the Dutch-Friesian breed can conveniently live and produce for seven and, including the preliminary period, for sixteen months on a ration consisting of straw, potatoes and concentrates having an average calcium content (including calcium in drinking water) of 0.22 per cent (varying from 0.17 to 0.25 per cent) in the dry matter. There was found to be an inverse relationship between the calcium content of the ration and the absorption coefficient. The absorption coefficient of calcium ranged from 28.7 to 83.8 per cent when the calcium content of the ration varied from 0.44 to 0.17 per cent. For sixteen months, the calcium-phosphorus ratio of the ration varied from 0.4 to 0.8. Bone biopsy was successfully performed using a universal drill.