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  • 1
    Publication Date: 1976-03-09
    Description: The frequencies of the first four sloshing internal wave modes in two superposed fluid layers contained in a circular channel are calculated for two positions of the free surface and for various ratios of the depths of the two layers. Flow patterns are given for the first four sloshing modes for the case in which the fluids occupy a semicircular space and the depth of the upper layer is one-quarter of the radius. It is hoped that the results obtained will provide a guide for estimating the frequencies of sloshing internal wave modes in long lakes. © 1976, Cambridge University Press. All rights reserved.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 2
    Publication Date: 1977-09-27
    Description: The stability of time-periodic flows in a circular pipe is investigated. The disturbance is assumed to be axially symmetric and to have a small amplitude, so that the governing differential equation is linear. Calculations are carried out for the first ten modes for a range of values of the frequency of the primary motion, of the wavenumber of the disturbance, and of the Reynolds number of the primary flow. In the ranges of the parameters for which the calculations have been carried out, the flows are found to be stable and, as for Stokes flows (von Kerczek & Davis 1974), it is conjectured that the flows under study here are stable for all frequencies and all Reynolds numbers. © 1977, Cambridge University Press. All rights reserved.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 3
    Publication Date: 2016-08-18
    Description: SUMMARYThe objective of the present study was to evaluate the effects of isovalerate supplementation on growth performance and ruminal fermentation in pre- and post-weaning dairy calves. Forty-eight Chinese Holstein male calves at 15 days of age and 45·1 ± 0·36 kg body weight (BW) were assigned randomly to four groups. The treatments were: control, low-isovalerate, moderate-isovalerate (MIV) and high-isovalerate (HIV) with 0, 3, 6 and 9 g isovalerate per calf per day, respectively. Isovalerate was hand-mixed into milk in pre-weaning calves and the concentrate portion in post-weaning calves. The study lasted 75 days, including a 15-day adaptation period followed by a 60-day sampling period. Weaning was conducted when calves were 60 days old. Six calves were chosen from each treatment at random and slaughtered at 30 and 90 days of age. Average daily weight gain increased linearly whether during pre-weaning or post-weaning period with increasing isovalerate supplementation. Dry matter intake linearly increased at 90 days of age with increasing isovalerate supplementation. During weaning, ruminal pH and ammonia nitrogen (N) decreased linearly, whereas total ruminal volatile fatty acid concentration increased linearly with increasing isovalerate supplementation. The ratio of acetate to propionate increased linearly with increasing isovalerate supplementation due to increased acetate concentration and the unchanged propionate concentration. Activities of caboxymethyl-cellulase, cellobiase, xylanase and pectinase linearly increased at 90 days of age, α-amylase and β-amylase activities linearly increased at 30 and 90 days of age. Relative quantities of Butyrivibrio fibrisolvens, Ruminococcus albus, Fibrobacter succinogenes and Ruminococcus flavefaciens increased linearly with increasing isovalerate supplementation. Ruminal fermentation, enzyme activities and cellulolytic bacteria were higher for HIV and MIV than for the control. The present results indicate that isovalerate accelerated growth of calves by improving ruminal fermentation, microbial enzyme activities and cellulolytic bacteria growth during weaning. In the experimental conditions of the current trial, the optimum isovalerate dose was about 6·0 g isovalerate per calf per day.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 4
    Publication Date: 2010-05-28
    Description: SUMMARYThe objective of the present study was to evaluate the effects of betaine supplementation on rumen fermentation, lactation performance and plasma characteristics in dairy cows. Twenty multiparous Holstein dairy cows (597±11·8 kg body weight (BW), 88±4·5 days in milk (DIM) and average daily milk production of 26·3±0·5 kg/cow) were used in a replicated 4×4 Latin square experiment. The treatments were: control (without betaine), low-betaine (LB), medium-betaine (MB) and high-betaine (HB) with 0, 50, 100 and 150 g supplemental anhydrous betaine/cow/day, respectively. Betaine was hand-mixed into the top one-third of the daily ration at feeding. Experimental periods were 30 days with 15 days of adaptation and 15 days of sampling. Dry matter (DM) intake was not affected with increasing the betaine supplementation. There were linear increases in milk yield and fat-corrected milk yield (corrected to 40 g fat/kg) and a linear and quadratic increase in milk fat concentration with increasing the betaine supplementation, whereas the proportion and yield of milk protein and lactose, and feed efficiency, were not affected. Ruminal pH and ammonia N linearly decreased, whereas total volatile fatty acid (VFA) concentration linearly and quadratically increased with increasing the betaine supplementation. The ratio of acetate to propionate (A:P) linearly increased from 3·06 to 3·53 as betaine supplementation increased. Digestibility of DM linearly increased, whereas digestibilities of organic matter (OM), crude protein (CP), neutral detergent fibre (NDF) and acid detergent fibre (ADF) in the total tract were quadratically increased with increasing the betaine supplementation. Plasma concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) were lower for betaine supplementation than for control, and were linearly decreased by betaine supplementation. The results indicate that supplementation of mid-lactation dairy cow diets with betaine increased milk yield through increased feed digestion. Betaine supplementation may benefit lactation performance when methionine supply is limiting.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 5
    Publication Date: 2009-01-23
    Description: SUMMARYThe objective of the current study was to evaluate the effects of calcium propionate supplementation on rumen fermentation, urinary excretion of purine derivatives (PD) and feed digestibility in the total gastrointestinal tract of steers. Eight ruminally cannulated Simmental steers (462±14 kg) were used in a replicated 4×4 Latin square arrangement of treatments with experimental periods of 21 days. The treatments were: control (without calcium propionate), LCaP (calcium propionate – low), MCaP (calcium propionate – medium) and HCaP (calcium propionate – high) with 100, 200 and 300 g calcium propionate per steer per day. Diet consisted of 0·60 maize stover and 0·40 concentrate (dry matter (DM) basis). DM intake (average 9 kg/day) was restricted to a maximum of 0·90 of ad libitum intake. Ruminal pH (range of 6·7–6·5) linearly (P
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 6
    Publication Date: 2012-03-01
    Description: SUMMARYThe high molecular weight glutenin subunits (HMW-GS) and glutenin macropolymer (GMP) in wheat grain are important characteristics that affect the quality of wheat products. Light intensity, as one of the environmental factors affecting grain yield and quality, has been studied extensively; however, little is known about its impact on HMW-GS and distribution of GMP granules in wheat grain. In the present study, two strong-gluten winter wheat cultivars with different subunit compositions were used to evaluate the effect of shading at different grain-filling stages on changes in HMW-GS and distribution of GMP granules in wheat grains. No effects of shading on initial formation time of each individual subunit were found; they responded similarly to shading with an increase in relative content, though the accumulation amount per grain of each individual subunit was decreased due to a decrease in grain weight induced by shading. Shading at different grain-filling stages, especially at the middle grain-filling stage, led to a significant increase in GMP content during grain filling; however, the proportions (by volume, number and surface area) of the larger GMP granules were increased by shading at middle and late grain-filling stages and decreased by shading at early grain-filling stage. It was also found that the content of total HMW-GS was positively correlated with volume proportions of larger GMP granules and negatively correlated with volume proportions of small GMP granules, which indicated that the pattern of response of distribution of GMP granules to shading was closely related to the regulatory effect of shading on the HMW-GS.
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    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 7
    Publication Date: 2017-08-15
    Description: SUMMARYThe current experiment was conducted to evaluate the effects of different dietary protein levels and rumen-protected folic acid (RPFA) supplementation on ruminal fermentation, microbial enzyme activity, bacterial populations and urinary excretion of purine derivatives (PD) in growing beef steers. Low-protein (LP) or high-protein (HP) diets were fed to eight ruminally cannulated first-generation cross-bred (Blonde d'Aquitaine × Simmental) beef steers with or without RPFA supplementation. Steers were fed a total mixed ration, and dietary concentrate to maize silage ratio was 50 : 50 (dry matter (DM) basis). No interaction between dietary crude protein (CP) levels and RPFA supplementation was observed during the experiment. Ruminal pH was unaffected by RPFA supplementation, but decreased with increasing dietary CP levels. Ruminal total volatile fatty acid concentration increased with increasing dietary CP levels or RPFA supplementation. Molar proportion of acetate increased with RPFA supplementation, but tended to decrease with increasing dietary CP levels. The proportion of propionate decreased with RPFA supplementation, but was unaffected by dietary CP levels. As a result, the acetate to propionate ratio increased with RPFA supplementation, but tended to be lower for the HP diets than the LP diets. Ammonia-nitrogen content decreased with RPFA supplementation, but increased with increasing dietary CP levels.In situruminal degradability of maize straw and concentrate increased with increasing dietary CP levels or RPFA supplementation. Microbial enzyme (carboxymethyl-cellulase, cellobiase, xylanase, pectinase,α-amylase and protease) activity, bacterial populations (Ruminococcus albus,Ruminococcus flavefaciens,Butyrivibrio fibrisolvens,Prevotella ruminicola,Fibrobacter succinogenesandRuminobacter amylophilus) and urinary PD excretion increased with increasing dietary CP levels or RPFA supplementation. The current study showed that increasing dietary CP levels from 109·1 to 130·7 g/kg DM or supplementing 75 mg RPFA improved ruminal fermentation and microbial protein synthesis by increasing bacterial population and microbial enzyme activity.
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    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 8
    Publication Date: 2014-12-05
    Description: SUMMARYBatch cultures of mixed rumen micro-organisms were used to evaluate varying enzyme products with high xylanase activity (EPX), four of which were recombinant single xylanase activity developmental enzyme products (EPX1–EPX4, products of xylanase genes derived from Trichoderma harzianum, Trichoderma reesei, Orpinomyces and Aspergillus oryzae, respectively), for their potential to improve in vitro ruminal fermentation of three forages [maize (Zea mays) stover (MS), rice (Oryza sativa) straw (RS) and Guimu No. 1 grass (Pennisetum americanum×Pennisetum purpureum, GM)]. The enzyme product EPX5, derived from Trichoderma longibrachiatum, was used as a positive control that could improve in vitro fermentation of forages. Enzymes were supplied at dose rates of 0 (control), 20 (low), 50 (medium) and 80 (high) enzymic units of xylanase/g of dry matter (DM). There were no interactions between EPX and dose for the fermentation characteristics evaluated. Increasing EPX dose linearly increased gas production (GP) kinetic characters [i.e. asymptotic GP (VF), half time when GP is half of the theoretical maximum GP (t0·5), and initial fractional rate of degradation (FRD0)] and methane (CH4) production from RS and GM at 24 h, and increased degradability of DM at 24 h for MS and RS. A linear increase in degradability of neutral detergent fibre (NDF) of the three forages at 24 h was observed with increasing dose of EPX, but at 48 h only NDF degradability of RS was increased. There were differences in the effects of EPX on degradability of DM and NDF from RS at 24 h, with EPX4 having the highest and EPX1 having the lowest. In addition, increasing EPX dose linearly increased acetate proportion at 24 h and total volatile fatty acids (TVFA) at 48 h in MS. Increasing EPX dose linearly increased TVFA at 24 h, and ammonia-nitrogen (NH3-N) concentration at 48 h in RS. For GM, linear or quadratic effects of dose on acetate and butyrate concentration were observed at 24 and 48 h. The present study indicates that applying EPX to low-quality forages has the potential to improve rumen degradability and utilization. Furthermore, EPX from different sources differed in their effects when applied at the same dose rate, with the responses being forage-specific. For RS, the EPX derived from A. oryzae showed the greatest positive effects on forage degradation; whereas for MS and GM, the source of micro-organism where EPX gene was derived did not affect the degradation, with little difference among the EPX evaluated.
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    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 9
    Publication Date: 2018-03-01
    Description: The present study evaluated the effects of isovalerate supplementation on the development of the small intestinal mucosa in dairy calves. Forty-eight Chinese Holstein bull calves at 15 days of age and 45.1 ± 0.36 kg of body weight were assigned randomly to four groups. The treatments were control, low-isovalerate, moderate-isovalerate and high-isovalerate with 0, 3, 6 and 9 g isovalerate per calf per day, respectively. The study comprised 75 days with a 15-day adaptation period followed by a 60-day sampling period. Calves were weaned at 60 days of age. Six calves were chosen from each treatment at random and slaughtered at 30 and 90 days of age. The small intestine morphology and activities of amylase and trypsin improved significantly with increasing age. No interaction between treatments and age was observed. The small intestine length, mucosa layer thickness, villus height and crypt depth increased linearly with increasing isovalerate supplementation. However, the ratio of villus height to crypt depth was not affected by treatment. Activities of amylase and trypsin increased linearly. The lactase activity increased linearly during the 75-day period and for pre-weaned calves but was unaltered for post-weaned calves. The relative mRNA expressions of growth hormone receptor, insulin-like growth factor-1 receptor and sodium-glucose co-transporter-1 in the small intestine mucosa increased linearly, and a similar pattern was observed for the expression of peptide transporter-1 in the duodenum and proximal jejunum. The results suggested that small intestine development was promoted by isovalerate in a dose-dependent manner.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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