Change-over Experiment Research Articles

Helium to hydrogen changeover experiments in JET

In fusion devices a part of the hydrogen retained by implantation has been demonstrated to be accessible during plasma operation and can be removed from the wall by He or isotope exchange with plasma. Starting with a wall devoid of H2 and D2 due to 2weeks of He campaign a series of change over experiments from He to H2 has been carried out in JET. Hydrogen plasma concentrations up to 85–90% have been reached after only 7 pure H pulses, for a total of ∼210s of plasma operation whilst an accessible wall inventory of ∼2.0×1023D (∼1g of T) has been evaluated. Extrapolation to ITER shows that accessible T content would be 21.3g, 2.63g and 1.63g respectively for C, C/Be/W and Be/W as materials facing the plasma. Finally, these quantities are “small” compared to retention by codeposition which will dominate the retention with time since this is a cumulative process.

Nitrogen metabolism in dairy cows fed restricted amounts of grass–clover silage supplemented with seeds from narrow-leafed lupin or pea

Twelve dairy cows in mid to late lactation were fed iso-nitrogenous diets (161 g CP/kg DM, forage:concentrate ratio 65:35) where rolled barley and coarsely ground seeds from either narrow-leafed lupin or field pea supplemented grass–clover silage. Feed allowance was individually restricted and fixed (18.8 ± 0.6 kg dry matter/day) throughout the experiment to avoid refusals. The experiment was of 2 × 2 change-over design and utilized a previous change-over experiment with 3 periods as covariate. Nitrogen balance was assessed by quantitative urine sampling and fecal spot sampling in eight cows whereas rumen metabolism was studied in four cannulated cows. Production of energy corrected milk was 24.3 kg/day with the lupin diet and 23.2 kg/day with the pea diet ( P < 0.05). Daily milk fat yield was also higher ( P < 0.05) with the lupin diet. Proportion of feed N excreted in milk did not differ between diets. Milk urea concentration, as well as the amounts of total urinary N and urinary urea were higher ( P < 0.05) for the lupin diet, while urinary N proportion of feed N only tended ( P = 0.08) to be higher with the lupin diet. N balance was lower with the lupin diet. Digestibilities of organic matter, neutral detergent fiber and crude protein did not differ between diets and neither did ruminal pools of these constituents. In addition, there were no differences between the diets with respect to the ruminal concentrations of NH 3-N and total volatile fatty acids, and only minor differences in ruminal pH and ruminal concentrations of iso-acids and α-amino-N. It is concluded that the higher fat content in lupins compared to peas is an advantage in typical Scandinavian home-grown rations and probably explains the higher milk yield in this experiment. Differences in protein utilization between lupins and peas are of small magnitude when fed ground without thermal processing. In practical feeding, ad libitum forage allowance may create response differences between lupin seeds and peas not observed in this experiment.

Effects of restriction of silage fermentation with formic acid on milk production

The study was conducted to evaluate the effects of silage fermentation quality and type of supplementation on milk production. Thirty two Finnish Ayrshire dairy cows were used in a cyclic change-over experiment with four 21-day experimental periods and 4 × 2 × 2 factorial arrangement of treatments. Silage fermentation was modified with formic acid (FA), which was applied at the rates equivalent to 0 (FA0), 2 (FA2), 4 (FA4) or 6 (FA6) litres t-1 grass of pure formic acid (as 100% FA). Dietary treatments consisted of four silages, a protein supplementation (no supplement or rapeseed meal 1.8 kg d-1) and a glucogenic substrate (no supplement or propylene glycol 225 g d-1). Increasing the application rate of FA restricted silage fermentation curvilinearly, as evidenced by higher concentrations of ammonia N and butyric acid in FA4 than FA2 silage. Similarly the use of FA resulted in curvilinear changes in the silage dry matter intake and milk yield. The highest milk and protein yields were achieved with FA6, while the milk yield with FA2 was higher than with FA4. Interactions were observed between silage type and supplementation. Rapeseed meal increased milk yield irrespective of the extent of silage fermentation, but the magnitude of response was variable. Propylene glycol was most beneficial with restrictively fermented silages FA4 and FA6. In conclusion, restriction of silage fermentation with a high rate of formic acid is beneficial in milk production. Interactions between silage composition and concentrate types suggest that the responses to supplementary feeding depend on silage fermentation characteristics.;

The effect of cutting time of grass silage in primary growth and regrowth and the interactions between silage quality and concentrate level on milk production of dairy cows

Two silages were prepared from the primary growth (PG) of timothy-meadow fescue sward at early (E) and late (L) stage of growth. The subsequent regrowth (RG) areas were further harvested at early (EE and LE) and late (EL and LL) stages of growth resulting in six silages in total. The silages were fed ad libitum to 24 lactating Finnish Ayrshire cows and supplemented with 8 or 12 kg concentrate per day in a cyclic change-over experiment with four 21-day periods and 6 × 2 factorial arrangement of treatments. The quality of silages varied markedly within and between the harvests although variation was greater within PG than RG. Postponing the harvest in PG decreased silage dry matter (DM) intake by 0.48 kg and energy corrected milk yield (ECM) by 0.61 per 10 g decrease in silage D-value (concentration of digestible organic matter in DM), while responses and the range between the diets were clearly smaller when RG silages were fed. On average, ECM yield was higher when PG rather than RG silages were fed. The mean response to increased concentrate DM intake was 0.62 kg ECM using diets based on PG. The response increased with increasing growth stage of grass being 0.34 and 1.01 kg ECM / kg additional concentrate DM for E and L, respectively. The difference was mainly mediated by the differences in substitution rates (reduction in silage DM intake per increase in concentrate DM intake, kg/kg), which were 0.71 and 0.22 for E and L, respectively. The ECM response to increased concentrate allowance was on average greater when RG rather than PG silages (0.92 vs. 0.62 kg/kg concentrate) were fed. Milk production of dairy cows reflected the intake of metabolizable energy and no differences in the utilization of it were found between diets based on silages harvested from PG and RG. However, intake of RG silages was slightly lower than that of comparable PG silage, but definite reasons for that could not be identified.

Exocrine pancreatic secretion in pigs fed sow's milk and milk replacer, and its relationship to growth performance1

The objective of this study was to quantify and compare the effects of sow's milk and 2 milk replacer diets (containing clotting or non-clotting protein sources) on exocrine pancreatic secretion, plasma cholecystokinin, and immunoreactive cationic trypsin in pigs. In addition, the relationship between exocrine pancreatic secretion and growth in milk-fed pigs was studied. In a changeover experiment, 9 chronically catheterized pigs of 6.6 +/- 0.19 kg of BW were studied for 3 wk. Pigs were assigned to each of 3 diets. Exocrine pancreatic secretion was measured from the third to the seventh day on each diet. The protein content and trypsin activity of the pancreatic juice were measured. Blood samples were taken at 10 min before and after milk ingestion and were analyzed for cholecystokinin and immunoreactive cationic trypsin. Pancreatic protein and trypsin secretion did not differ between pigs fed sow's milk and those fed milk replacer, but the volume secreted was less for the pigs fed sow's milk (0.75 vs. 1.03 mL x kg(-1) x h(-1); P < 0.01). A postprandial response to milk intake was not observed. The 2 milk replacer diets did not affect exocrine pancreatic secretion differently. The average exocrine pancreatic secretion (volume, 0.94 mL x kg(-1) x h(-1); protein, 4.28 mg x kg(-1) x h(-1); trypsin, 1.65 U x kg(-1) x h(-1)) was intermediate between literature values for suckling and weaned pigs. Plasma cholecystokinin was elevated (approximately 18 pmol x L(-1)) and showed low correlations with the pancreatic secretion traits. Plasma immunoreactive cationic trypsin was not significantly related to any of the pancreatic secretion traits and should therefore not be used as an indicator for exocrine pancreatic function in milk-fed pigs. Exocrine pancreatic secretion varied substantially among individual pigs (protein, 0.22 to 13.98 mg x kg(-1) x h(-1)). Pancreatic protein and trypsin secretion showed a positive, nonlinear relationship with performance traits. It was concluded that neither specific sow's milk ingredients nor the protein source are responsible for a low pancreatic protein secretion in suckling pigs. Exocrine pancreatic secretion was positively correlated with ADG in pigs at an identical milk intake.

The effect of fermentation quality on the voluntary intake of grass silage by growing cattle fed silage as the sole feed1

This study was designed to separate the effect of fermentation quality on voluntary intake of grass silage from other feed factors affecting intake. Variations in DMI were quantified, and the impact on intake was modeled. The relationships between individual silage components and intake were examined. A partially balanced changeover experiment with 30 Norwegian Red steers (137 +/- 16.4 kg of BW) was carried out to determine the intake of 24 silages and of hay harvested from the same parent crop within 60 h. Five forages were fed at a time in each of five 3-wk periods. Every 3-wk period was preceded by 2 wk of feeding a standard silage. Silage DMI ranged from 1.79 to 2.65, with a mean of 2.38 kg x 100 kg of BW(-1) x d(-1). Hay DMI averaged 2.43 kg x 100 kg of BW(-1) x d(-1). Ranges (mean) for the composition of silages were as follows: DM, 166 to 237 (213) g/kg; water-soluble carbohydrates, 16.3 to 70.9 (33.0) g/kg of DM; acetic acid, 11.5 to 64.7 (28.6) g/kg of DM; propionic acid, 0 to 5.2 (1.0) g/kg of DM; butyric acid, 0 to 25.1 (6.0) g/kg of DM; lactic acid, 2.2 to 102 (49.3) g/kg of DM; and NH3-N (not corrected for additive-derived N), 89.3 to 255 (153) g/kg of total N. Silage DMI was closely (P < 0.05) related to DM, ADL, VFA, lactic acid, total acids, the lactic acid:total acids ratio, ADIN, NH3-N (not corrected), histamine, tryptamine, cadaverine, and the total sum of amines (the explained variation in intake ranged from 14 to 53%). The 2 best models describing silage DMI included concentrations in the silage of propionic acid, butyric acid, and lactic acid, and these models explained 75 and 84% of the variation in DMI. The strong correlation (r = 0.84, P < 0.05) between total NH3-N and butyric acid concentrations in silages indicates that these variables described the same variation pattern. The inclusion of NH3-N in the equations describing the effect of fermentation quality on DMI of low-DM grass silage was less useful than that of butyric acid. This was due to the confounded relationship between the NH3-N concentration in silages and the use of ammonium-containing preservatives and to difficulties in correcting for the added ammonium.

Effects of protective gates at concentrate feed stations on behaviour and production in dairy cows: A brief note

Concentrate feed stations for dairy cows improve feeding management allowing frequent individual feeding. Concentrates are highly valued by cows and then a cause for competition and aggression. The production and cow welfare may be compromised because of frequent displacements of cows visiting the feed station. A comparison was made between two concentrate feeding stations with two groups of 20 cows each in a change-over experiment lasting for 18 weeks. One feeding stations was equipped with protective gates, which closed while the cow in the feeding station was fed concentrates which eliminated displacement of this cow. No difference in milk production was obtained. The number of visits to the feeding station with protective gates was fewer than to the control (12.7 versus 15.9; P < 0.001) as was the number of unrewarded visits (without feed supply) (3.7 versus 5.3; P < 0.01). The number of aggressions directed towards cows in the concentrate feeding station was reduced by 65% in the feed station with protective gates as was the number of displacements of cows from the concentrate feeding station by 67%. It was concluded that the protective gates reduced competition and made concentrate feeding more efficient.

The effects of mirrors on the welfare of caged rabbits

AbstractMirrors can enrich the environment of some social animals kept in isolation. In this study, the effect of mirrors on the behaviour of isolated, or partially isolated, caged rabbits was tested. In a changeover experiment, four treatments were investigated: isolated without mirrors; partially isolated (with a conspecific housed behind a partition) without mirrors; isolated with mirrors; and partially isolated with mirrors. Behaviour was recorded during the first hour for which the rabbits were in the cages with the stimuli, and then again after one week. Initially, the rabbits' alertness increased, which may be because they perceived the mirror image to be a potential threat. The mirrors also stimulated investigation by the rabbits, which initially scraped them rapidly with their forepaws (scrabbling) and sniffed them. Although sniffing was maintained until the end of the week, scrabbling was not, probably because the rabbits failed to elicit the normal reactions of a conspecific from their mirror images. Mirrors also reduced the time rabbits spent sitting in their living area looking out of the cage, and increased their behavioural complexity, as determined from the number of behaviours performed per minute. In a second experiment, the responses of seven rabbits to four stimuli were recorded: a conspecific; a toy animal; a mirror; and a blank card. The rabbits were presented with pairs of stimuli at either end of a marked board. The responses of the rabbits to mirrors were more similar to their responses to a blank card or to a soft toy than to a conspecific. Although the rabbits did not respond to mirror images as if they were conspecifics, the mirrors may have had benefits to the complexity of behaviour of rabbits in small cages.

Effect of forage conservation method, concentrate level and propylene glycol on the fatty acid composition and vitamin content of cows' milk

Based on potential health benefits, there is a need to develop effective strategies for enhancing milk fat concentrations of cis-9 18:1, 18:3 n-3 and conjugated linoleic (CLA) content in milk without compromising the sensory or storage characteristics of processed milk or dairy products. Sixteen Finnish Ayrshire dairy cows were used in a cyclic change-over experiment with four 21-d experimental periods and a 4 x 2 x 2 factorial arrangement of treatments to evaluate the effects of forage conservation method, concentrate level and supplements of propylene glycol (PG), and their interactions on milk fatty acid composition and vitamin content. Experimental treatments consisted of four conserved forages offered ad libitum, supplemented with two levels of a standard concentrate (7 or 10 kg/d) and PG (0 and 210 g/d) fed as three equal meals. Primary growths of timothy and meadow fescue sward were conserved by ensiling with none (NA), an inoculant enzyme preparation (IE) or a formic acid based (FORM) additive or as hay 1 week later. Conservation of grass by drying rather than ensiling resulted in lower forage 18:2n-6, 18:3n-3, total fatty acid and fat-soluble vitamin concentrations. In spite of lower intakes, milk fat 18:2n-6 and 18:3n-3 content was higher (P < 0.05) for hay than for silage diets (12.1, 9.6, 9.6 and 9.3 and 5.00, 3.51, 4.27 and 2.93 g/kg total fatty acids, for hay, NA, IE and FORM silages, respectively). Forage conservation method had no clear effects on milk trans 18:1 or CLA content. Compared with silage, hay diets resulted in milk containing lower (P < 0.001) riboflavin, alpha-tocopherol and beta-carotene concentrations, but had no effect on ascorbic acid, thiamine, pyridoxine or retinol content. Feeding more concentrates had no effect on milk fatty acid composition or milk vitamin content, other than lowering (P < 0.001) 16:0 concentrations from 348 to 338 g/kg fatty acids. Supplements of PG led to small (P < 0.05) increases in milk 13:0 anteiso and 15:0 content from 1.06 and 11.3 to 1.22 and 12.6 g/kg fatty acids and reduced (P < 0.05) the concentrations of ascorbic acid (16.1 v. 15.1 g/kg milk).

Nitrogen balance, microbial protein production, and milk production in dairy cows fed fodder beets and potatoes, or barley.

Fourteen multiparous midlactation dairy cows were used in a change-over experiment with 3 periods and 3 diets to evaluate the effects of fodder beets and potatoes on N metabolism, microbial protein production, and milk production. A basal ration of alfalfa/grass silage offered ad libitum, 1 kg of grass hay and 1 kg of heat-treated rapeseed cake was supplemented with 5 kg DM of either rolled barley/raw potatoes 80:20 (BAP), fodder beets/raw potatoes 80:20 (BEP) or rolled barley (BA). Urine and feces were collected quantitatively from 8 cows and ruminal samplings, and evacuations were performed on 4 cannulated cows. Intake and production did not differ between BAP and BA, but the BEP diet lowered intake of both silage and total ration by 0.9 kg DM. Daily yield of energy-corrected milk (ECM) was decreased by 1.7 and 2.3 kg compared with BAP and BA, respectively. Milk urea concentration was 1 mM lower with the BEP diet. The proportion of feed N recovered in milk was 20 to 21% for all diets. With the BEP diet, urinary N amount and proportion were reduced correspondingly to the lower total N intake. Fecal N amount remained unchanged, and hence nitrogen apparent digestibility decreased by 5 percentage units with the BEP diet. Microbial protein production, assessed by allantoin excretion, tended to be highest with the BAP diet. Acetate proportion of VFA was lowered by the BEP diet, while proportions of propionate and butyrate both tended to increase. Different fermentation patterns, probably related to differences in rumen microbiota, could explain why changes in energetic efficiency and milk composition reported in the literature did not occur in the actual experiment when roots replaced barley. Compared with barley, roots appeared to have a greater negative effect on silage intake in conjunction with a prewilted silage with high intake potential allowed ad libitum and this decreased milk production by a magnitude corresponding to the lower intake of ME.

Optimum dietary amino acid pattern and limiting order of some essential amino acids for growing-furring blue foxes (Alopex lagopus)

AbstractThe optimum pattern and limiting order of some essential amino acids for growing-furring blue foxes were assessed from nitrogen (N) retention responses. Total tract digestibility and N balance trials were carried out on 24 weaned blue fox males in an 8 ✕ 5 cyclic change-over experiment. Eight experimental diets were prepared by removing proportionately about 0·4 of each of the amino acids studied – methionine + cystine, lysine, threonine, tryptophan and histidine – successively from the amino acid control diet. The main source of protein in the amino acid control diet was casein and an amino acid mixture was added to bring the calculated crude protein (CP) content up to the level of 170 g/kg dry matter (DM). Low-protein (CP 95·7 g/kg DM) and high-protein (CP 166·6 g/kg DM) diets, the protein proportion of which was casein protein, served as negative and positive control diets, respectively. The reduction in N retention when one amino acid in turn was deleted from the amino acid control diet was calculated, and a regression analysis was made between N retention and relative amino acid intake. Data on the animals’ intake of each limiting amino acid and those on the amino acid control diet were used. The optimum amino acid pattern, expressed relative to lysine = 100, proved to be: methionine + cystine 77, threonine 64, histidine 55 and tryptophan 22. The first-limiting amino acids were methionine + cystine. Blue fox responses (N retention, weight gain) to deletion of methionine + cystine from the diet were very severe and exceeded those to deletion of any other amino acid. Moreover, removing methionine + cystine from the diet significantly impaired the apparent digestibility of organic matter, reducing it to a level even lower than that of the low-protein diet. After methionine + cystine, the next-limiting amino acid in casein-based diets was threonine, followed by histidine and tryptophan. The results show the importance of verifying the sufficiency of dietary methionine + cystine in the practical feeding of blue foxes.

Comparison of heat-treated rapeseed expeller and solvent-extracted soya-bean meal as protein supplements for dairy cows given grass silage-based diets

AbstractSixteen early to mid lactation Finnish Ayrshire dairy cows were used in a cyclic change-over experiment with four 21-day experimental periods and a 4 5 2 factorial arrangement of treatments to evaluate the effects of heat-treated rapeseed expeller and solvent-extracted soya-bean meal protein supplements on animal performance. Dietary treatments consisted of grass silage offered ad libitum supplemented with a fixed amount of a cereal based concentrate (10 kg/day on a fresh weight basis) containing 120, 150, 180 or 210 g crude protein (CP) per kg dry matter (DM). Concentrate CP content was manipulated by replacement of basal ingredients (g/kg) with either rapeseed expeller (R; 120, 240 and 360) or soya-bean meal (S; 80, 160 and 240). Increases in concentrate CP stimulated linear increases (P &lt; 0·05) in silage intake (mean 22·5 and 23·8 g DM per g/kg increase in dietary CP content, for R and S, respectively) and milk production. Concentrate inclusion of rapeseed expeller elicited higher (P &lt; 0·01) milk yield and milk protein output responses (mean 108 and 3·71 g/day per g/kg DM increase in dietary CP content) than soya-bean meal (corresponding values 62 and 2·57). Improvements in the apparent utilization of dietary nitrogen for milk protein synthesis (mean 0·282 and 0·274, for R and S, respectively) were associated with higher (P &lt; 0·05) plasma concentrations of histidine, branched-chain, essential and total amino acids (35, 482, 902 and 2240 and 26, 410, 800 and 2119 µmol/l, respectively) and lower (P &lt; 0·01) concentrations of urea (corresponding values 4·11 and 4·52 mmol/l). Heat-treated rapeseed expeller proved to be a more effective protein supplement than solvent-extracted soya-bean meal for cows offered grass silage-based diets.

The value of malt distillers’ grains ensiled with molassed sugar beet pellets as a feed for dairy cows

AbstractIn one experiment twenty‐four Holstein Friesian cows, average 43 d post‐partum, were used in a changeover design experiment to evaluate the replacement of a cereal‐based concentrate supplement (C) by an ensiled mixture (MGBP) of malt distillers’ grains and molassed sugar beet pellets. The cows were offered grass silage ad libitum [dry matter (DM) content 170 g kg−1, crude protein (CP) concentration 160 g kg DM−1, metabolizable energy (ME) concentration 10·9 MJ kg DM−1] and either C or MGBP at one of three levels (3, 6, 9 kg DM d−1). The composition of C and MGBP were DM content: 853 and 296 g kg−1, CP concentration: 202 and 187 g kg DM−1, ME concentration: 12·6 and 10·8 MJ kg DM−1 respectively. The cows ate all the C supplement but the intakes of MGBP were 2·7, 4·9 and 6·4 kg DM d−1 for the 3, 6 and 9 kg DM d−1 levels of MGBP respectively. Total DM intakes (kg d−1) were 12·5, 15·6, 18·2 for treatments 3‐C, 6‐C and 9‐C and 13·1, 14·4 and 15·9 (s.e., 0·90) for treatments 3‐MGBP, 6‐MGBP and 9‐MGBP respectively. Milk yields (kg d−1) for treatments 3‐C, 6‐C and 9‐C were 19·9, 23·2 and 24·2, respectively, and for treatments 3‐MGBP, 6‐MGBP and 9‐MGBP were, 20·3, 21·3 and 23·0 respectively (s.e., 1·05). Milk fat contents (g kg−1) for treatments 3‐C, 6‐C and 9‐C were 42·8, 42·3, 43·5 respectively and for treatments 3‐MGBP, 6‐MGBP and 9‐MGBP were 39·5, 38·7 and 38·2 (s.e, 1·86), respectively, and milk protein contents (g kg−1) for treatments 3‐C, 6‐C and 9‐C were 30·5, 30·6, 31·8, respectively, and for 3‐MGBP, 6‐MGBP and 9‐MGBP were 30·0, 30·8 and 31·2 (s.e., 0·66) respectively. Milk yield and milk protein contents were significantly higher for the higher levels of supplementary feeding but there was no difference between the types of supplement. The milk fat contents were significantly lower on the MGBP than C supplements.In a second experiment fifteen Holstein Friesian cows, average 126 d post‐partum, were used in a changeover experiment to evaluate the replacement of all (treatment M) or half (treatment MS) of the grass silage (S) in their diet by a mixture of MGBP and straw. All cows received 5·1 kg DM d−1 of concentrate feed. Forage DM intakes were 8·3, 11·2 and 14·2 kg DM d−1 for the S, MS and M treatments respectively. Milk yields (kg d−1) for S, MS and M treatments were 17·0, 19·4 and 20·0 (s.e., 0·56) respectively. Corresponding contents of milk fat and protein (g kg−1) were 42·0, 41·4, 38·6 (s.e., 0·37) and 33·8, 34·1, 34·2 (s.e., 0·42).Ensiled mixtures of malt distillers’ grains and molassed sugar beet pellets can be used to replace some of the conventional concentrates or grass silage for dairy cows giving moderate yields without a loss of production.

Effect of molassed sugar beet pulp on nutrient utilisation and metabolic parameters during exercise.

The aim of this study was to investigate the effect of partly replacing oats with molassed sugar beet pulp in a traditional hay/oat diet on nutrient utilisation and metabolic parameters in exercising horses. In a change-over experiment, 4 Standardbred geldings were fed a hay and oat-based diet (Oat diet) and a hay and oat-based diet where oats was partially replaced with molassed sugar beet pulp (MSBP diet). Each experimental period was 21 days during which total collection of faeces and urine was made and an exercise test (ET) performed. The crude fat digestibility was lower on the MSBP diet (P<0.05), while there were no differences in digestibility of other nutrients and energy and in the urinary excretion of nitrogen and energy. At rest plasma insulin were lower (P<0.05) 60 and 90 min postprandially on the MSBP diet, while no differences were found in plasma glucose and insulin between the diets during the ET. The peak plasma and muscle lactate values were lower (P<0.05) on the MSBP diet and the content of muscle glycogen was higher (P<0.05) after the ET on the MSBP diet. In conclusion, the metabolic response differed between diets giving a lower lactate response and a higher glycogen content in muscle after exercise on the MSBP diet. This suggests that the dietary carbohydrate composition may influence the rate of glycogenolysis with lactate production and support the hypothesis that MSBP can replace oats in a hay based diet without impairing nutrient utilisation and metabolic response in exercising horses.

Effect of forage conservation method, concentrate level and propylene glycol on intake, feeding behaviour and milk production of dairy cows

AbstractThe current study was conducted to establish if effects on animal performance due to differences in forage composition resulting from conservation method could be compensated for by increases in concentrate feeding or supplements of a gluconeogenic substrate. Thirty-two Finnish Ayrshire dairy cows were used in a cyclic changeover experiment with four 21-day experimental periods and a 4 ✕ 2 ✕ 2 factorial arrangement of treatments to evaluate the effects of forage conservation method, concentrate level and propylene glycol (PG), and their interactions, on intake, feeding behaviour and milk production. Experimental treatments consisted of four conserved forages offered ad libitum, supplemented with two levels of a cereal-based concentrate (7 or 10 kg/day) and PG (0 and 210 g/day) offered as three meals of equal size. Forages were prepared from primary growths of timothy and meadow fescue swards and ensiled using no additive (NA), an inoculant enzyme preparation (IE) or a formic-acid based (FA) additive or conserved as hay 1 week later. Cows given silage-based diets had higher (P 0·001) forage dry-matter (DM) intakes (mean increase 0·76 kg/day), spent less (P 0·001) time eating and chewing (mean response -159 and -119 min/day, respectively) and produced more (P 0·05) energy-corrected milk (ECM), milk fat and milk lactose (respective mean responses 1·52, 0·098 and 0·033 kg/day) than animals given hay-based diets. Use of an additive during ensiling further improved (P 0·05) silage DM intake, ECM yield and milk protein secretion (mean 0.72, 0.70 and 0.038 kg/day, respectively). Dietary inclusion of PG decreased forage DM intake for hay, IE and FA silage-based diets (mean –0·14, –0·16 and –0·42 kg/day, respectively) but elicited positive responses (mean 0·57 kg/day) for cows given NA silage. Furthermore, PG supplementation had no (P &gt; 0·05) effects on ECM yield or milk protein output but depressed (P 0·05) mean milk fat content from 46·6 to 45·6 g/kg. Increases in concentrate feeding were associated with a reduction in the total amount of time cows spent eating, chewing and ruminating and elicited (P 0·001) mean DM intake, ECM yield, milk fat and milk protein responses of 1·5, 1·62, 0·061 and 0·064 kg/day, respectively. Use of a gluconeogenic substrate or increases in concentrate feeding were unable to compensate for variations in animal performance due to forage conservation method.

Effect of forage conservation method, concentrate level and propylene glycol on diet digestibility, rumen fermentation, blood metabolite concentrations and nutrient utilisation of dairy cows

The current study was conducted to establish if variations in nutrient supply due to forage conservation method could be compensated for by increases in concentrate feeding or supplements of a glucogenic substrate. Thirty two Finnish Ayrshire dairy cows were used in a cyclic change-over experiment with four 21-day experimental periods and a 4×2×2 factorial arrangement of treatments to evaluate the effects of forage conservation method, concentrate level and propylene glycol (PG), and their interactions, on digestibility, rumen fermentation, blood metabolite concentrations and nutrient utilisation. Experimental treatments consisted of four conserved forages offered ad libitum, supplemented with two levels of a cereal-based concentrate (7 or 10 kg per day) and PG (0 and 210 g per day) fed as three equal meals. Forages were prepared from primary growths of timothy and meadow fescue swards and ensiled using no additive (NA), an inoculant enzyme (IE) preparation or a formic acid (FA)-based additive or conserved as hay 1 week later. Forage conservation method had only minor effects on digestibility. Increases in concentrate feeding reduced the digestibility of neutral detergent fibre (NDF) while PG supplements tended to decrease that of nitrogen. Rumen fermentation of grass silage-based diets was characterised by higher molar proportions of butyrate and branched chain volatile fatty acids (BCVFA) and lower proportions of acetate compared with hay-based diets. Use of an ensiling additive reduced molar proportions of butyrate, while relative to FA silage, rumen fermentation of IE silage was associated with lower proportions of acetate and higher proportions of propionate and BCVFA. Increases in concentrate feeding resulted in a shift towards butyrate at the expense of acetate, while PG supplementation resulted in a rumen fermentation with higher proportions of propionate and lower proportions of acetate. Relative to silage fed animals, cows receiving hay-based diets had higher plasma concentrations of glucose and lower concentrations of insulin and beta-hydroxybutyrate (β-OHB). Increases in concentrate feeding tended to increase glucose concentrations while PG supplements elevated glucose but lowered plasma β-OHB concentrations. Differences in rumen fermentation associated with the ingestion of forages conserved using different methods were sufficient to suggest an important role on subsequent nutrient utilisation. Increases in concentrate feeding or supplements of a glucogenic precursor were unable to compensate for variations in nutrient supply due to forage conservation method.

Effects of level of nitrogen fertilizer application and various nitrogenous supplements on milk production and nitrogen utilization of dairy cows given grass silage-based diets

AbstractSixteen Finnish Ayrshire dairy cows were used in a cyclic change-over experiment with four 28-day experimental periods and a 4✕2 factorial arrangement of treatments to evaluate the effects of dietary nitrogen (N) source on dry-matter (DM) intake, diet digestibility, milk production, blood metabolite concentrations and N utilization. Experimental treatments consisted of two silages prepared from timothy and meadow fescue swards fertilized with either 52 or 104 kg N per ha (SLand SH, respectively) offered ad libitum supplemented with one of four concentrate supplements offered at 10 kg/day. A basal concentrate (control) was formulated from (g/kg on an air-dry basis) barley (307), oats (460), molassed sugar-beet pulp (200) and vitamins and minerals (33). Three isonitrogenous concentrates were prepared by replacement of basal concentrate ingredients (g/kg) with urea (14·4), wheat-gluten meal (WGM; 57·2) and heat-moisture treated mechanically expelled rapeseed cake (RSC; 188), respectively. Harvesting of secondary growths receiving higher applications of fertilizer N increased silage N content (19·2 and 23·6 g/kg DM, for SLand SH, respectively) but decreased water-soluble carbohydrate concentrations (respective values 149 and 93 g/kg DM). Increases in N fertilizer had no effect on silage DM intake, output of energy-corrected milk, milk fat or milk protein secretion, while provision of additional N in concentrate supplements improved all of these parameters. However, the magnitude of silage DM intake responses to additional N in concentrates was higher (P&lt; 0·05) for SLthan SHsilage-based diets. Increases in dietary N content derived from silage or inclusion of urea, WGM or RSC in concentrate supplements led to a decline in the proportion of N intake secreted in milk. Relative to N derived from silage or urea, WGM and RSC supplements had beneficial effects on milk production. Both the quantity and quality of dietary N sources should be considered in future attempts to improve the efficiency of on-farm N utilization.

Ileal apparent digestibility of amino acids in growing pigs given a cassava root meal diet with inclusion of cassava leaves, leucaena leaves and groundnut foliage

AbstractIleal apparent digestibility of amino acids (AA) in a cassava root meal and soya-bean meal diet without and with an inclusion (150 g/kg) of sun-dried cassava leaves, ensiled cassava leaves, leucaena leaves and groundnut foliage was studied in a change-over experiment (5 ✕ 5) with post-valve T-caecum cannulated growing pigs.The ileal apparent digestibility of dietary crude protein (CP) and AA were unaffected by the inclusion of groundnut foliage (P&gt; 0·05). In contrast, when sun-dried and ensiled cassava leaves, and leucaena leaves were included in the diet the ileal apparent digestibility of dietary CP and AA were significantly reduced (P&lt; 0·05).The estimated ileal apparent digestibilities of essential and non-essential AA in groundnut foliage were higher (P&lt; 0·05) than those of the other leaf products and there were no differences among cassava leaves and leucaena leaves (P&gt; 0·05). On average ileal apparent digestibility of essential AA was 0·71 in groundnut meal and 0·56 in cassava and leucaena leaves.It was concluded that, under tropical conditions, groundnut foliage has the potential to improve the dietary protein and AA supply and to replace partially soya-bean meal, in low fibre diets for growing pigs. Further, when conventional protein-rich foods are not available, cassava and leucaena leaves may also have the potential to improve the protein and AA supply for pigs.

Comparison of hydrogen and tritium uptake and retention in JET

During previous Joint European Torus (JET) deuterium-to-tritium change-over experiments, subdivertor tritium concentrations were compared with those measured at the strike point region and found to differ significantly during the first few discharges, which was correlated with wall saturation. New deuterium-to-hydrogen fueling experiments in JET have been made and are compared to these previous experiments. Rates of hydrogenic species exchange are similar to those found in previous tritium experiments, granting differences in divertor configuration and mass ratio. In the new experiments, measurements of the CD and CH molecular band intensities near the divertor strike point monitor an intermediate stage of particle exchange between the plasma and wall. The CD/CH ratio correlates well with both the plasma and subdivertor concentration. The neutral transport code EIRENE and the wall hydrogen trapping and diffusion code WDIFFUSE have been used to evaluate the wall saturation. It appears that chemically-related processes play a role in mediating the plasma–wall exchange.

Competition for Total Mixed Diets Fed Restrictively Using One or Four Cows per Feeding Station

A study was made of feed intake, behaviour and production in 16 dairy cows with one and four cows per feeding station (treatment 1c and 4c, respectively) with a restricted amount of a total mixed diet. The computerized feeding stations comprised continuously weighed feed-troughs placed at feeding gates. The cows were divided in two groups and were studied in a change-over experiment in which each group was submitted to each treatment twice. Video recordings and the computerized feeding system were used to collect data on the order of social dominance, aggression levels, time budgets and the consumption of feed and water. The effects of individual dominance value (DV), age, eating rate and energy requirements were recorded on ingestive behaviour. The cows on treatment 4c visited the feeding stations more often (106% more visits and 76% more meals) and shortened their feeding times by 50%, resulting in higher consumption rates compared with treatment 1c. In addition, aggression increased, resulting in a greater number of displacements at feeding. It is concluded that the investigated combination of competition for feeding space and restricted amounts of feed cannot be recommended.