Showing papers in "The Journal of Agricultural Science in 1977"
TL;DR: In this article, an artificial fiber bag technique was evaluated for assessing the proportions of dietary D. M. and N which disappear in the rumen and the most important factor determining the variability in disappearance from bags incubated together was the sample size in relation to bag size.
Abstract: The artificial fibre bag technique was evaluated for assessing the proportions of dietary D. M. and N which disappear in the rumen. The most important factor determining the variability in disappearance from bags incubated together was the sample size in relation to bag size. For incubation of 5 g air dry feed, a bag size of 17 ✗ 9 cm was found to be adequate. There were also variations in substrate disappearance between animals and between days of incubation. It was estimated that three sheep and the measurement of substrate disappearance twice were necessary in order to obtain acceptable repeatability.The technique was found to be satisfactory as a simple and rapid guide for measuring nutrients disappearance in the rumen such as protein degradation and carbohydrate fermentation. It has been used in subsequent work to measure the effect of features of the rumen environment, such as pH and NH3 concentration, on rate of fermentation.
804 citations
TL;DR: The results show that it should be easier for breeders to select for high nitrogen uptake from among heavy than from among light genotypes, and although dwarf genotypes tended to be light, none of the correlations found was strong enough to render it impossible to produce dwarf genotype capable of giving high yields of high-protein grain.
Abstract: In a field experiment with 47 wheat genotypes, plant samples were taken at anthesis and maturity and analysed for nitrogen. Taking means over all genotypes, the plants contained at anthesis 83 % of the total present at maturity, while at maturity 68 % of the plant nitrogen was present in the grain.There was significant genetic variation in most of the component attributes determining nitrogen uptake. At anthesis, the heaviest plants contained most nitrogen. Because the nitrogen concentration in the leaves (average 2·8%) was much greater than in the stems and ears (average O8 %) and the leaves comprised, on average, 37 % of the plant weight at anthesis, variation in leanness was the main cause of variation in the nitrogen content of plants of a given weight. During grain filling, plants which lost the most dry weight from their stems and leaves took up the least nitrogen.It is suggested that the strong positive correlation between the accumulation of dry matter and of nitrogen, both until anthesis and during grain filling, occurred because both carbon assimilation and nitrate reduction depend on energy made available from chloroplasts. In addition, assimilate is required to sustain the growth of roots which is necessary for continued nitrate uptake.The results show that it should be easier for breeders to select for high nitrogen uptake from among heavy than from among light genotypes. However, although dwarf genotypes tended to be light, none of the correlations found was strong enough to render it impossible to produce dwarf genotypes capable of giving high yields of high-protein grain.
242 citations
TL;DR: Ninety-nine Finnish Landrace x Dorset Horn ewes in lamb to Suffolk rams were used in a comparative slaughter experiment to assess the effects of numbers of foetuses on the growth of the products of conception, and the mathematical model implies that the differences originate in early pregnancy, when the factor is very close to unity, and that the mean weights gradually diverge.
Abstract: Seventy-nine Finnish Landrace x Dorset Horn ewes in lamb to Suffolk rams were used in a comparative slaughter experiment to assess the effects of numbers of foetuses on the growth of the products of conception. The mean number of foetuses was 2·7, with a range from 1 to 5. The ewes were individually penned and given a standard diet with metabolizable energy concentration 7·7 MJ/kg and N concentration 21 g/kg, rationed at 2 kg/day during the first month and 1·25 kg/day during the second and third. Allowances beyond that time were on two scales and depended on the number of foetuses being carried as diagnosed by radiography. The ewes were slaughtered between 50 and 145 days of gestation. The gravid uterus was dissected into foetal, placental, foetal fluid and empty uterus components. Equations were fitted to the weights of each component to describe the effects of stage of gestation, litter size and ewe weight. For the mean weight per foetus (Y, kg) the preferred equation isIn (Y)= 2·419–17·574e-0.01976t–00079ft+0–0046w,where tis the time in days from conception, / is the number of foetuses and wis the weight (kg) of the ewe at mating. This is a version of the Gompertz equation, with additional terms to express the effects of / and w.The weights of the placenta and of the empty uterus were similarly fitted by versions of the Gompertz equation but the mean weight of fluids per foetus (Z, kg) or, rather, its natural logarithm was best described by a third degree polynomial, which isIn(Z) = –11·518 + 0–326t;–0·00316t2+0·0000102t3.None of the weights was significantly affected by the level of feeding in late pregnancy.Estimates of mean weights from the equations and of daily rates of gain in weight from the first differentials of the equations are tabulated against stage of gestation and litter size, and the forms of the weight, growth rate and specific growth-rate curves are illustrated graphically.The equation for foetal weight estimates that at the end of pregnancy the mean weight per foetus is reduced by a factor of 0–89 for each additional foetus being carried. The mathematical model implies that the differences originate in early pregnancy, when the factor is very close to unity, and that the mean weights gradually diverge. In the absence of direct evidence this would appear to be the simplest hypothesis, rather than the assumption in most of the earlier literature that the effect is entirely confined to the last 4 or 5 weeks of gestation.Just before parturition the total daily weight gain of quadruplet foetuses was about 250 g and was associated with a similar gain in weight of foetal fluids, the ratio of fluid weight to foetal weight appearing to increase with litter size. The ewes were clearly under considerable physical stress. It is suggested that this aspect must be closely considered when greater prolificacy is sought.
170 citations
TL;DR: Nitrogen anabolism was reduced by parasitism, but pair-feeding showed that reduced food intake rather than a specific effect on protein metabolism was responsible.
Abstract: Four groups of eight sheep, 4 months of age and reared parasite-free from birth, were used to investigate the effect of the abomasal parasite Ostertagia circumcincta on the intake and efficiency of utilization of food. One group (CI) was killed initially as control. Two further groups (ALC and ALI) were offered ad libitum a complete ruminant diet. The ALI group was dosed daily for 14 weeks with 4000 infective larvae. Sheep in a further group (PF) were individually paired to members of the ALI group and offered the same amount of food as was consumed by their pair. Balances of N, Ca and P, and the digestibility of energy and N were determined for the ALI and PF groups during weeks 2–3, 7–8 and 12–13. After 14 weeks of dosing the sheep were killed and the bodies of these and the CI sheep analysed for water, fat, N, Ca and P contents. Parasitism caused a 20% reduction of food intake by week 2 which was maintained throughout the experiment. Apparent digestibility of nitrogen was reduced from 60 to 44% at weeks 2—3 but subsequently showed a gradual recovery. Nitrogen balances of infected sheep were inferior to those of controls which, with the exception of the first trial during which urinary N excretion of infected sheep was increased, was entirely related to the reduced digestibility. Energy digestibility was reduced by 2 percentage units during all trials. Weight gain of ALI sheep was only 80% of that of PF sheep. Nitrogen anabolism was reduced by parasitism, but pair-feeding showed that reduced food intake rather than a specific effect on protein metabolism was responsible. Fat deposition was markedly reduced. It was calculated that the gross efficiency of utilization of metabolizable energy for growth was reduced by 30% compared with either ALC or PF controls. Mineral deposition (Ca or P) in the skeleton of the ALI sheep was reduced to about 35 and 50% of that in ALC and PF groups, respectively.
119 citations
TL;DR: Moisture content responses on a weight basis, together with air-filled porosity responses, showed large differences between treatments particularly at the time of crop emergency, indicating substantial alterations in the soil profile hydrology.
Abstract: Soil responses to deep (30–35 cm) and normal (15–20 cm) mouldboard ploughing, chisel ploughing and zero-tillage have been compared for 7 years in a field experiment growing continuous spring barley near Edinburgh. The soil was of variable texture, from moderately well-drained sandy loam overlying loam to imperfectly to poorly drained sandy clay loam overlying clay loam, classified as stagnogleyic brown earth to cambio stagnogley soil. Soils of this type derived from Carboniferous till are widely used for cereal production in south-east Scotland. Measurements of soil physical properties were made at crop emergence, midseason and at harvest to characterize seasonal and long-term responses to tillage and traffic. After the first 3 years bulk density responses varied little within or between seasons, showing a compacted horizon from 0–15 cm under zero-tillage and a looser horizon from 21–33 cm under deep ploughing compared with normal ploughing. Immediately below the depth of normal ploughing there was no difference in bulk density between this treatment and zero-tillage while in some years the chisel-ploughing treatment was denser. Moisture content responses on a weight basis, together with air-filled porosity responses, showed large differences between treatments particularly at the time of crop emergency, indicating substantial alterations in the soil profile hydrology. Expressed on a volume basis the increased moisture content near the surface under zero-tillage became more pronounced and the other effects disappeared. Cone resistance responses were proportionately larger than those for bulk density and showed one major difference in that below the depth of ploughing cone resistance was greater for zero-tillage than normal ploughing in the sixth and seventh seasons, but not previously. For bulk density, but probably not for cone resistance, there were no increases after the third season of zero-tillage, the soil reaching an equilibrium density for the current management practices and machinery usage.
109 citations
TL;DR: The quantitative digestion of the energy, carbohydrate and nitrogen moieties of the three diets and the production of volatile fatty acids and microbial protein within the rumen were measured using five sheep fitted with re-entrant cannulae at the proximal duodenum and terminal ileum.
Abstract: S.24 perennial ryegrass was conserved by ensiling directly (control) and after treatment with a solution of formaldehyde at the rate of 6 g HCHO/100 g crude protein. After storage for 90 days, part of the formaldehyde-treated silage was dried in a high-temperature drier.The quantitative digestion of the energy, carbohydrate and nitrogen moieties of the three diets and the production of volatile fatty acids and microbial protein within the rumen were measured using five sheep fitted with re-entrant cannulae at the proximal duodenum and terminal ileum.Treatment with formaldehyde depressed organic matter and energy digestion within the rumen compared with untreated silage (P < 0·001) and a further depression was observed on the dehydrated material. Both formaldehyde-treated silages showed enhanced flows of total amino acids into the small intestine compared with the control silage and net absorption from the small intestine was elevated by 13 and 21% respectively on these two diets. On the untreated silage over 71% of the protein entering the small intestine was microbial in origin whereas, due to depressed microbial growth and increased protection of feed protein from rumen fermentation, microbial protein comprised only 17% of duodenal protein on the two formaldehyde-treated silage diets. Fifteen and 81 % of the dietary protein passed undegraded through the stomachs to the duodenum on the control and the two formaldehyde-treated silage diets respectively.Total VFA production within the rumen was not significantly influenced by the treatments imposed, but on the untreated silage only 56% of the energy apparently digested in the rumen was converted to VTA energy whilst a mean value of 74% was recorded on the other two diets.Estimates of the total energy absorbed gave values of 10·6, 11·9 and 10·7 MJ/kg D.M. for the control, formaldehyde and dried, formaldehyde silage diets with absorbed protein energy representing 21, 22 and 26% of the total absorbed energy respectively.
93 citations
TL;DR: In this paper, the effect of methods of tillage on soil properties (strength, bulk density, nutrient distribution and fauna) and the effects on root development and the absorption of nutrients from different depths in the soil were investigated.
Abstract: This paper gives measurements of soil physical conditions and root growth made in the experiment described in the previous paper. The effect of methods of tillage on soil properties (strength, bulk density, nutrient distribution and fauna) and the effects on root development and the absorption of nutrients from different depths in the soil were investigated. The procedures used for these measurements are described.Greater soil compaction occurred in all years after direct drilling. The growth of seminal roots of young plants was reduced by direct drilling in each year but only in the first year were there significant differences in root development between treatments at later stages of growth. Similarly, in each year early shoot growth was reduced by direct drilling but, with the exception of the first year, the plants were subsequently able to compensate adequately. Direct drilling resulted in more earthworms being present in the soil, and caused the surface soil to be more friable and contain a higher concentration of available phosphorus and potassium.
92 citations
TL;DR: Climbing beans were superior to bush beans in acetylene reduction and specific nodule activity, but differed little in nodule development, and two varieties, Cargamanto and Sangretoro, were outstanding in fixation.
Abstract: Twenty cultivars of P. vulgaris differing in growth habit, and inoculated with an efficient strain of R. phaseoli, were sampled weekly in the period 22—99 days after planting. Acetylene reduction and specific nodule activity were similar to or better than those reported for other grain legumes, and were higher than achieved by a soya-bean cultivar. Though the period of active fixation was limited, nitrogen gains estimated at 25—30 kg/ha/growing cycle were obtained. Climbing beans were superior to bush beans in acetylene reduction and specific nodule activity, but differed little in nodule development. Two varieties, Cargamanto and Sangretoro, were outstanding in fixation. Differences between varieties in nodule to root ratio, and in rate of N accumulation in the leaves were shown. Both groups of plants stored appreciable starch in the stem after flowering. The results are related to the need for N fertilization in Latin America.
85 citations
TL;DR: It is concluded that tillers, during their initiation and early growth, compete with the mainshoot for a limited supply of resources, thus reducing the size of the main shoot.
Abstract: Barley plants normally produce some tillers which die at an early stage, without bearing an ear. To investigate the proposition that these non-ear-bearing tillers may be wasteful of plant resources, two experiments were made in which the effect of tiller growth on the growth and final size of the main shoot was assessed. In one experiment, tillers were removed at a very early stage when they were a few mm long, or later when they were just emerging from the subtending leaf sheath. In the other experiment the main shoot was removed from the embryo and the size of the coleoptile tiller which grew in its absence was measured.Tiller removal affected the growth and final size of the main shoot. Leaves emerged more quickly on the main shoot of the detillered plants and were bigger and sometimes more in number. The main shoot of the detillered plants was heavier and it bore a greater weight of grain because the ear had more and heavier grains. In the experiments where the main shoot was removed the coleoptile tiller produced more leaves, which emerged more rapidly and it bore more grains than the coleoptile tiller of the intact plants.It is concluded that tillers, during their initiation and early growth, compete with the main shoot for a limited supply of resources, thus reducing the size of the main shoot. As some of the resources of the plant are used to produce tillers which die at an early stage and make no contribution to the final grain yield, it appears that they should be regarded as wasteful and that their production may reduce the final grain yield. The physiology of the initiation, growth and early death of these non-ear-bearing tillers requires further investigation.
79 citations
TL;DR: In this article, the authors suggest that water supply may be a more important factor controlling yield than either solar radiation or plant competition, with the period following pod setting being especially vital.
Abstract: Field experiments, using Vicia faba cvs Herz Freya and/or Maris Bead were made in 1972–5. Population densities were varied and shading treatments were applied. Soil moisture content was monitored throughout. Maximum dry-matter production per plant and per unit area were similar in 1973 and 1974, but lower in 1975. Variations in growth were associated with variations in soil moisture content. When pods began to fill, plants reached maximum total water content and root growth ceased.Increasing density enhanced, and shading retarded both leaf senescence and seed maturation. Maximum potential seed yield (5–6 t/ha) in 1974 was obtained at 32plants/m2. In 1975, yields of 7–9 t/ha were obtained at 66 plants/m2, probably as a result of retention of many pods by the plants. Since total dry-matter production was lower in 1975 than in 1974 we conclude that photosynthetic potential did not limit yield in the earlier year.From the patterns of rainfall, soil moisture and plant water content, we suggest that water supply may be a more important factor controlling yield than either solar radiation or plant competition, with the period following pod setting being especially vital. At this time plant water requirement may often be in excess of supply.
76 citations
TL;DR: The digestibility of the herbage ingested exerted a dominant influence on herbage organic matter (OM) intake, which increased at a constant rate as organic matter digestibility (OMD) increased throughout the range observed, 55–81% in Expt 1 and 53–63% inExpt 2.
Abstract: Experiments were carried out at the Grassland Research Institute, U.K. (Expt 1) and the Universidad Central de Venezuela, Maracay (Expt 2), to study the influence of sward characteristics upon the herbage intake of young grazing cattle. In both studies the animals were strip-grazed in small groups on a series of plots, at a generous herbage allowance.The digestibility of the herbage ingested exerted a dominant influence on herbage organic matter (OM) intake, which increased at a constant rate as organic matter digestibility (OMD) increased throughout the range observed, 55–81% in Expt 1 and 53–63% in Expt 2. Intakes were similar in the two experiments at 60–65% OMD, but the rate of decline with decreasing digestibility was much greater in Expt 2 than in Expt 1.Intake was affected to a small extent in Expt 2 by the weight of herbage, the proportion of green material, and the extended height of the sward. In Expt 1 the intake from plots of primary growth was approximately 10% greater than that from secondary growths at equivalent digestibility and crop weight.The implications of these observations to techniques of grazing management are discussed.
TL;DR: In this paper, the digestibility of grass cell wall constituents determined in a digestion trial were compared with those obtained by suspending various isolated cell wall preparations in nylon bags in the rumen of a sheep.
Abstract: The digestibilities of grass cell wall constituents determined in a digestion trial were compared with those obtained by suspending various isolated cell wall preparations in nylon bags in the rumen of a sheep. Particular attention was paid to acetyl groups and to individual sugars, which were determined in both cases by gas liquid chromatography.For dried grass and hay in the digestion trial the cell wall constituents showed digestibilities decreasing in the following order: arabinose, galactose, glucose, xylose, acetyl, lignin.For a leaf cell wall preparation derived from all cell types except mesophyll, the nylon bag technique allowed the same order of digestibilities; rhamnose and uronic acids were also measured and found to be rapidly digested. Mesophyll cell walls placed in nylon bags were more readily digested than non-mesophyll. All the sugars, and also acetyl groups, were digested to the same extent.In a grass cell wall preparation isolated from sheep faeces, tested similarly, xylose and glucose were digested to the same extent, but acetyl groups were less digested.Removal of acetyl groups, using sodium ethoxide, which left the sugar composition and lignin content unchanged, increased the digestibility particularly of the cell walls from faeces.The results are discussed with reference to the relationship between cell wall composition and digestibility.
TL;DR: In this paper, the potential acetylene reducing activity per plant varied little from year to year and environmental factors such as water supply exerted increasing effects on activity, such as shading prolonged activity and delayed nodule senescence.
Abstract: N fixation data, estimated by the acetylene reduction technique and by total N content are given for the field experiments reported by Sprent, Bradford & Norton (1977).Maximum potential acetylene reducing activity per plant varied little from year to year. At low population densities a maximum rate of activity was observed shortly after flowering. As density increased this maximum became less pronounced and environmental factors (such as water supply) exerted increasing effects on activity. Shading prolonged activity and delayed nodule senescence.Total plant N continued to increase almost to seed maturation. As plants aged, the acetylene reduction technique progressively underestimated N accumulation. Maximum Nfixed/ha/year was over 600 kg. Itis concluded that the potential for N fixation in this crop is sufficient to sustain high yields.
TL;DR: There had been a progressive increase in the efficiency of energy utilization for the production of edible meat and the need to differentiate between the live-weight maintenance needs of fast and slow growing animals which may be of similar live weights but differing ages is drawn.
Abstract: Groups of Bos indicus (Boran) and Bos taurus (Hereford) × Bos indicus steers were kept at constant live weights of 185, 275 and 450 kg for periods of up to 24 weeks. Maintenance of these live weights was achieved by control of the daily ration of a diet having an energy concentration of 10·477 MJ metabolizable energy (ME)/kg d.m. AS time progressed it was noted that less of the diet had to be fed daily to maintain constant live weight. Body composition of steers slaughtered at 0, 12 and 24 weeks showed that the live weights had been maintained by the compensating effect of empty body weight gains and digestive tract content-weight losses.No significant differences were found between slaughter groups for the energy values of the boneless carcass meat nor the internal deposits of empty digestive tract, omental and mesenteric fat. It was therefore concluded that there had been a progressive increase in the efficiency of energy utilization for the production of edible meat.The percentage reduction of daily food intake from 3 to 24 weeks necessary to maintain the prescribed live weights ranged from 51·8% for the 185 kg Borans to 17·9% for the 450 kg ¾ Boran × Hereford cross-breds.Comparison with published estimates for maintenance of live weight showed that after 24 weeks at constant live weight the 185 and 275 kg Borans and the 450 kg ¾ Borans needed 50·5, 37·9 and 34·2% less and the 275 kg Hereford × Boran cross-breds and 450 kg ¾ Herefords 40·8 and 37·9% respectively less food than estimated.Correction for age effects on the fasting metabolic rates of the 185 and 275 kg weight groups reduced the difference between theoretical and actual maintenance requirements from 50·5, 37·9 and 40·8% to 37·3, 29·3 and 33·8% respectively.Attention is drawn to the need to differentiate between the live-weight maintenance needs of fast and slow growing animals which may be of similar live weights but differing ages.
TL;DR: It is concluded that choice of primary tillage system on this chalk downland soil was not a significant factor in the production of either spring barley or winter wheat.
Abstract: The results are reported of two experiments made on a silt loam soil over chalk on downland in southern England. Three primary tillage treatments (ploughing, deep or shallow tine cultivation) were compared with direct drilling for their effects on the growth of spring barley during the years 1969–74 and winter wheat during 1974–8.No significant differences in barley population density or early growth were recorded. In the first 2 years more grain was produced on the shallow tined and direct-drilled plots than on those that were ploughed, but the differences did not persist into subsequent years. The mean yield of each treatment over the 4 years did not differ.Significant differences in population density and winter mortality of wheat occurred but these were not consistently associated with differences in yield. In this crop also the mean yields of the cultivation treatments over the 4 years were not significantly different.It is concluded that choice of primary tillage system on this chalk downland soil was not a significant factor in the production of either spring barley or winter wheat.
TL;DR: The results of analyses of yield variability in more than 500 trials of varieties of spring oats, spring wheat, spring barley and winter wheat are presented to provide guidance in planning future series of trials.
Abstract: This paper presents the results of analyses of yield variability in more than 500 trials of varieties of spring oats, spring wheat, spring barley and winter wheat. A table of critical percentage yield differences has been constructed for guidance in planning future series of trials.
TL;DR: In this paper, the acute thermoregulatory responses of normally feathered (control) and poorly feathered laying hens were studied in the ambient temperature range from 0 to 38 °C.
Abstract: The acute thermoregulatory responses of normally feathered (control) and poorly feathered laying hens were studied in the ambient temperature range from 0 to 38 °C.Core body temperature in the poorly feathered birds began to fall at between 15 and 20 °C but this difference from the controls was significant only at 0 and 5 °C, when there was severe hypothermia. The temperature on the skin of the back was significantly lower at 20 °C and below, but the comb temperatures did not differ.The rate of oxygen consumption in the poorly feathered hens was significantly higher than that of the controls at 30 CC and below; at the acclimation temperature (20–25 °C) the difference was about 62%. The rate of increase of heat production with falling ambient temperature was 2–6 W/ma/°C in the poorly feathered group and 1–0 W/ma/°C in the controls.Absolute rates of evaporative heat loss did not differ between the two groups.The ratio of the coefficients of dry heat transfer in the poorly feathered and control birds at 0–30 °C was 2–1:1.
TL;DR: Observations on acid-base balance and water intake indicated that inclusions of NaCl or NaHCO3 up to 20 g Na/kg D.M. were well tolerated by calves, and above this level there was a sharp increase in water intake, and with NaH CO3 there is a large base excess and high pH in the blood.
Abstract: Calves were reared on milk replacer up to 5 weeks of age and given ad libitum access to pellets and chopped straw from 1 to 10 weeks of age. Major ingredients of the pellets were ground barley (B) or ground barley and grass meal in a 6:4 ratio (G). Included in these two basal diets were NaCl or NaHCO 3 , each at 2, 11, 20 or 29 g Na/kg D.M. Calves on G diets ate more than those on B diets but grew at a similar rate. The replacement value of grass meal for ground barley was 1·36:1. Most responses to Na inclusions were unaffected by the basal diets. Before weaning there were linear increases in food intake and growth rate related to Na level in the diet. At 29 g Na/kg D.M., total D.M. intake/kg 0.75 and growth rate were respectively 31 and 23% greater than at 2 g Na/kg D.M. After weaning there were differential responses to the two salts. With NaHC0 3 there were linear increases in food intake and growth rate up to 20 g Na/kg D.M., at which level total D.M. intake/kg 0.75 and growth rate were respectively 36 and 44% greater than at 2 g Na/kg D.M. With NaCl the only significant response was that total D.M. intake at 11 g Na/kg D.M. was 16% higher than at 2 g Na/kg D.M. Observations on acid-base balance and water intake indicated that inclusions of NaCl or NaHCO 3 up to 20 g Na/kg D.M. were well tolerated by calves. Above this level there was a sharp increase in water intake, and with NaHCO 3 there was a large base excess and high pH in the blood.
TL;DR: It is concluded that in individually fed ewes a nutritional state characterized by plasma 3-hydroxybutyrate concentrations of 1·1 mmol/1 would constitute an acceptable compromise between an uneconomically high energy input and an excessive reduction in lamb birth weight.
Abstract: Individual feed intakes of housed mature Greyface (Border Leicester × Scottish Blackface) ewes were adjusted weekly to maintain plasma 3-hydroxybutyrate concentrations during the final 6 weeks of pregnancy at the following values: treatment 1 (adequately nourished; 17 ewes) less than 0·7 mmol/1; treatment 2 (moderately undernourished; 15 ewes) at about 1·1 mmol/1; treatment 3 (severely undernourished; 15 ewes) at about 1·6 mmol/1.The mean energy intakes (MJ metabolizable energy (ME)/day) required to maintain the prescribed nutritional states in single- and twin-bearing ewes were: treatment 1, 14·3 and 16·3; treatment 2, 10·6 and 11·6; treatment 3, 8·1 and 10·0 respectively.The moderate degree of undernourishment had no significant effect on the birth weight of single lambs, but reduced the birth weight of twins by 8·2%, while the more severe undernourishment reduced the birth weights of singles and twins by 21·5 and 25·8% respectively.Foetal energy requirements, estimated by regression analysis, appeared to decrease from more than 2 MJ ME/kg/24 h at 35 days prepartum to 1·54 MJ ME/kg/24 h in the week before parturition.The amounts of energy required to sustain the nutritional states of treatments 1–3 in non-pregnant ewes were calculated to be 348, 271 and 231 kJ ME/kg0.75/24 h, compared with a maintenance requirement, determined in this experiment, of 344 kJ ME/kg0.75/24h.It is concluded that in individually fed ewes a nutritional state characterized by plasma 3-hydroxybutyrate concentrations of 1·1 mmol/1 would constitute an acceptable compromise between an uneconomically high energy input and an excessive reduction in lamb birth weight.
TL;DR: In this paper, whole barley grains were either soaked in dilute sodium hydroxide solutions or sprayed with concentrated solutions, then incubated in bags in the rumen of sheep.
Abstract: Whole barley grains were soaked in dilute sodium hydroxide solutions or sprayed with concentrated solutions, then incubated in bags in the rumen of sheep. Rate of digestion was increased by the alkali, and spraying with 35 g NaOH/kg was concluded to be the optimum treatment. Whole barley treated in this way was as well consumed and digested by cattle as rolled barley, and better digested than untreated whole grain, but promoted a rumen pH one unit higher. Oats, wheat and maize were also treated successfully, as judged by digestion in bags. Urea added with NaOH remained stable; treated grain could be stored at 19% moisture without deterioration.
TL;DR: There are large differences in the pattern of rumen fermentation between wild and domestic mixed-feeding ruminants which reflect their respective food preferences.
Abstract: The relationship between the selected food and rumen fermentation was investigated in Thomson's gazelle, Grant's gazelle, impala and Maasai haired sheep and goats. All animals were shot in the same grass-bushland area within 1 week during the dry season.According to rumen contents, sheep were almost exclusively grazers. In goats, Thomson's gazelle and impala, grass accounted for about 70% of all plant parts identified. In Grant's gazelle, browse including Acacia seed constituted 68% of rumen ingesta. The two gazelle species showed a very marked preference for green grass leaves.In sheep and goat rumens, concentrations of NH3-N and volatile fatty acids, and in vitro fermentation rates (262 and 272 μmoles gasNTPD/g D.M./h, respectively) were lowest. In the wild ruminants, concentrations of fermentation end-products were higher and the rate of fermentation significantly (P < 0·05) faster, namely 420 in Thomson's gazelle, 356 in Grant's gazelle and 376 in impala. Rumen pH was not significantly different between species, with mean values ranging between 6·3 and 6·0. Total VFA concentrations ranged between 124 and 178 m-equiv/1 in the rumen and around 25 m-equiv/1 in the abomasum. Acetic acid accounted for about 75% of the total VFAs.It is concluded that there are large differences in the pattern of rumen fermentation between wild and domestic mixed-feeding ruminants which reflect their respective food preferences.
TL;DR: In this paper, the authors studied the fermentation characteristics of rumen in sheep fitted with rumen cannulae and found that the fermentation phase of the rumen was never completely O2-free, and that whilst a stable rumen fermentation existed in sheep fed the hay diet, and on this last mentioned diet abnormal values for rumen gas composition and VFA proportions were produced from time to time.
Abstract: Rumen fermentation characteristics were studied using sheep fitted with rumen cannulae. Diets of 100% hay and 20% hay:80% cooked flaked maize (concentrate diet) were fed at the maintenance level of energy intake as two equal portions per day. Both the gas and liquid phases of the rumen were continuously sampled over 33-h periods.Concentrations of O2 and N2 in rumen gas inoreased during feeding, whilst concentrations of CO2 and CH4 decreased. Thereafter the concentrations of both CO2 and CH4 rapidly increased. The CO2: CH4 ratio increased rapidly following feeding; it declined to baseline levels 2–4 h after feeding the hay diet, but with the concentrate diet the decline took longer. O2 concentration declined rapidly following feeding and was stable within the range 1–3% for long periods. At no stage was O2 absent from the rumen gas phase. H2 comprised 100–1500 μ1/1 and 100–6000 μ1/1 of the gas phase in sheep fed the hay or concentrate diets respectively and its concentration increased very rapidly with the onset of eating. CO concentration varied between 2 and 16 μ1/1 in the rumen gas of hay-fed animals and was not related to time after feeding. In concentrate-fed animals CO comprised 0—130 μ1/1 of rumen gas and increased very slowly after feeding.Eh and rH values ranged between —150 and —260 mV and 8·0 and 5·0 units respectively for rumen contents from animals fed the two diets. A diurnal cycle was evident, with the most oxidizing state being attained just before feeding, and the most reducing state just after feeding. The diurnal cycles were better denned by rH than by Eh. The magnitude of the decrease in rH (and pH) during feeding was greater for animals fed the concentrate than the hay diet. At no stage during feeding did Eh or rH change towards more oxidizing conditions. Changes in the concentration of H2 in rumen gas were related to changes in the rH of rumen contents.VFA molar proportions showed no changes during the 24-h cycle with hay-fed animals but showed erratic variation with concentrate-fed animals. When two sheep fed the concentrate diet were sampled daily for 21 days, it was shown that VFA molar proportions were not constant.It was concluded that the gas phase of the rumen was never completely O2-free, and that whilst a stable rumen fermentation existed in sheep fed the hay diet the fermentation appeared to be continuously changing in the concentrate-fed sheep, and on this last mentioned diet abnormal values for rumen gas composition and VFA proportions were produced from time to time.
TL;DR: It is concluded that genotypes which produce few large tillers having a high rate of survival should be able to achieve relatively high yields in drought conditions without sacrificing yield potential under optimal conditions.
Abstract: The effects of several detillering treatments on dry-matter production and grain yield in barley were investigated in a series of pot experiments using two water regimes. When ample water was provided, even quite severe reductions in the number of tillers only slightly reduced grain yield in spite of large effects on total shoot dry weight. When all the plants were grown with the same amount of water, however, the plants with few tillers tended to have greater grain yield, higher water use efficiency (in terms of grain yield) and higher harvest index than the plants permitted to tiller freely. This effect was probably related to the greater transpiration rates from the freely tillering plants which led to their suffering a greater degree of water stress than the plants with few tillers. This led to the freely tillering plants having a greater proportion of sterile ears and a lower harvest index. Water stress apparently had no effect on the grain yield of the main shoot or first tiller. It is concluded that genotypes which produce few large tillers having a high rate of survival should be able to achieve relatively high yields in drought conditions without sacrificing yield potential under optimal conditions.
TL;DR: It is suggested that for cows of moderate yield potential fed to Woodman's standards (Evans, 1960) the actual pattern of feeding a predetermined amount of concentrates has little effect on the yield or quality of milk.
Abstract: Ninety-six Friesian cows were used to determine the effects of pattern of allocation of a fixed amount of concentrates on milk yield during the treatment and residual periods (weeks 1–20 and 21–44 respectively) and on the whole lactation. Thirty-two were in their second and the remainder in their third or later lactation. Second-lactation cows were used to form separate blocks.Four treatments were imposed for the first 20 weeks of lactation; these were Graded (G), Woodman (W), High Fixed (HF), and Low Fixed (LF). The first three treatments involved the same total amount of concentrate but fed in different daily amounts. Treatment W received Woodman's standard (Evans, 1960) amounts of feed according to a predetermined lactation curve derived from earlier experience in the herd; treatment G reallocated the same allowance by feeding more than W in weeks 1–12 and less during weeks 13–20; the HF treatment was a fixed daily amount of 6·4 kg, in total also equal to W total. LF was a fixed daily amount of 4·0 kg/day. The maintenance allowance was the same for all cows within a block and based on hay, dried sugar-beet pulp and barley meal. During weeks 21–44 all cows within a block received the same treatment; either grazing or self-fed silage and supplementary concentrates according to the time of year.There were significant differences in milk yield during the treatment period resulting from plane of feeding (W, G and HF greater than LF; P < 0·001) but no significant differences arising from the pattern of feeding. In the residual period (weeks 21–44) there was no significant difference between the yields of second-lactation treatment groups. Thus for the whole lactation the yields of treatments G, W and HF were significantly greater than LF. However, for the older cows there were differences in the residual period and treatment groups G and LF gave significantly more milk than group W (P < 0·001 and P < 0·05 respectively). Over the whole lactation treatment group G gave significantly more milk than LF (P < 0·001), W (P < 0·01) and HF (P < 0·05). Furthermore, the increase in total lactation yield of G compared with W was 4·5 times the increase observed in weeks 1–20.Cows of both age groups on treatment HF, unlike those on treatments W and G, never achieved a distinct peak yield but their mean weekly rate of decline was significantly less.Live-weight changes varied between treatments and between age groups and were significantly correlated with milk yield in weeks 1–20.There were no significant effects of treatments on milk composition in either age group at any stage of the lactation. The minimum value for solids-not-fat content for the cows on the LF treatment was unacceptably low.It is suggested that for cows of moderate yield potential fed to Woodman's standards (Evans, 1960) the actual pattern of feeding a predetermined amount of concentrates has little effect on the yield or quality of milk. For cows of high potential a redistribution of concentrates to allow earlier more generous feeding will increase milk yield.The rate of decline of milk yield is a characteristic of both cow potential and pattern of feeding and an adoption of a standard 2½% a week should be viewed with caution.
TL;DR: In this paper, the molar composition of rumen volatile fatty acids (VFA) with straw diets was high in acetate (64-68%), with barley diets high in propionate (32-36%) and with molasses diets with high in butyrate (28-34%).
Abstract: Rumen fermentation, duodenal digesta flow and N balance were studied in three sheep fed diets which contained urea or fishmeal as nitrogen supplement and either barley straw, barley + corn starch or molassed wheat straw (60% molasses) as carbo-hydrate source.The molar composition of rumen volatile fatty acids (VFA) with straw diets was high in acetate (64–68%), with barley diets high in propionate (32–36%) and with molasses diets high in butyrate (28–34%). Rumen ammonia concentrations (RAC) were low and constant with fishmeal diets (< 10 mM) but varied with carbohydrate source with urea diets. RAC was very high (24 mM) after feeding molasses + urea.With barley and molasses diets 73–75% of digestible dry matter (DDM) was digested in the stomach, but only 54–59% with ground and pelleted straw diets. For all diets less N passed the duodenum than was eaten. The lowest daily duodenal N passage was with molasses + urea. Daily urinary N output was highest (P < 0·01) for this diet and nitrogen balance lowest.Daily intakes of amino acids differed widely between diets but differences in duodenal passage were not so great. Molasses + urea provided the lowest values for daily duodenal amino acid flow. The amino acid content of duodenal N (mM amino acid/16 g N) was relatively constant despite broad variation between diets. Digesta alanine and valine (mM/16 g N) were higher for barley than for straw diets (P < 0·05). Digesta methionine (mM/16 g N) was lower for fishmeal than for urea diets (P < 0·01).Very little sucrose reached the duodenum with any diet.It was concluded that the form of energy-yielding nutrient inuflenced duodenal N flow by affecting ammonia-N capture in the rumen, but that the amino acid content of duodenal N was little affected. The interaction between molasses and urea was not beneficial to efficient use of urea-N in this work when molasses was the major carbohydrate component of the diet.
TL;DR: Grain yields of 14 spring oat varieties grown at two levels of nitrogen in three seasons at two locations were compared as discussed by the authors, and a genotype × environment analysis demonstrated that the more recent varieties not only had higher yields but also were better adapted to high yielding environments.
Abstract: Grain yields of 14 spring oat varieties grown at two levels of nitrogen in three seasons at two locations were compared. A genotype × environment analysis demonstrated that the more recent varieties not only had higher yields but also were better adapted to high-yielding environments. Modern varieties demonstrated a yield improvement of 30% over the older varieties. Examination of components of yield by a series of simple correlations indicated that improvement in varieties by breeding has been associated with shortened straw and higher harvest indices. Within varieties, 1000-grain weight was the most stable character and harvest index the character which varied most consistently with variations in grain yield.
TL;DR: In this paper, five barley cultivation systems for spring-sown barley were tested on a clay to sandy-clay loam for 4 years and their cumulative effects on soil and crop measured.
Abstract: Five cultivation systems for spring-sown barley were tested on a clay to sandy-clay loam for 4 years and their cumulative effects on soil and crop measured. Four primary cultivations in the autumn, shallow (7·5 cm), medium (15 cm) and deep (23 cm) tine cultivation and mouldboard ploughing (23 cm deep) followed in spring by secondary cultivations and sowing, were compared with direct drilling seed into uncultivated soil after controlling weeds with herbicides. At the same rates of seed and fertilizer for all systems, direct drilling and shallow cultivation yielded significantly less grain than deeper tillage in the second year only; over 4 years the differences in mean yield were small and non-significant. In terms of crop output per unit of implement net energy (estimated) direct drilling was eight times more efficient than ploughing.Direct drilling and shallow cultivation caused concentration gradients of ‘available’ phosphorus and potassium to form in the top soil. Soil strength and to a lesser extent bulk density were greater without than with cultivation but these changes had only a relatively small effect on root distribution in the profile. In untilled soil the proportion of the root system was less in the surface 2·5–12·5 cm and greater in the 12·5–32·5 cm horizon than in shallow or deep tilled soil.Mean nitrogen uptake by the crop in the third and fourth seasons was least in direct - drilled barley probably due to lower rates of mineralization of soil nitrogen in compacted than tilled soil. It was deduced that for spring barley the ‘yield plateau’ was the same for each system but that optimal rates of nitrogen would be higher for crops in untilled than tilled soils.
TL;DR: In this paper, a consideration of input-output relationships relating energy intake to its probable utilization for growth, condition and lactation by dairy cows leads to a series of equations describing observable responses.
Abstract: A consideration of input-output relationships relating energy intake to its probable utilization for growth, condition and lactation by dairy cows leads to a series of equations describing observable responses. Energy is expressed in terms of units of milk equivalent, common to all equations, and the lactation curve, yn = ano e−cn is shown to be capable of biological interpretation, having regard to the subordinate equations from which it is derived. This expression relates milk production yn during a time interval n through the parameters a, b and c. The validity of the steps by which the function is developed is examined by reference to published work.
TL;DR: It is concluded that a naturally short daily feeding time and an independence of activity from the environmental heat load on the animals are advantageous characteristics for a species under domestication in a hot semi-arid environment.
Abstract: Studies of the day-time activity of night-enclosed eland, oryx, buffalo and cattle in a hot, semi-arid area in Kenya showed that, on average, eland spent 70% of the day feeding, oryx 60% and buffalo and cattle 52%.The distribution of activity throughout the day of all species was similar and the mobile activities of feeding and walking tended to be concentrated in the early morning and late evening.Correlation and multiple regression analyses were used to investigate changes in the activity of the animals in relation to changes in meterological and vegetative factors. The activity of both eland and buffalo was found to be particularly sensitive to the meterological factors.The duration of feeding for cattle and buffalo was related to the state of the vegetation, but that of the oryx was not. Similar analyses were not possible for eland.The activity of each species could be related to mouth size, feeding habits and the effectiveness of the animals' coat in dealing with conditions of high heat load.It is concluded that a naturally short daily feeding time and an independence of activity from the environmental heat load on the animals are advantageous characteristics for a species under domestication in a hot semi-arid environment.
TL;DR: In this article, the effect of protein protection on milk yield and milk composition was investigated in Jersey cows in their 6th and 8th week of lactation. But the results showed that the milk yield response to the protein supplements was mainly due to a higher daily intake of herbage.
Abstract: Twenty-one Jersey cows in their 6th–8th week of lactation grazed Chloris gayana pastures fertilized with nitrogen and were treated in three ways, no casein (control), casein (1 kg/cow/day) or formal-casein (1 kg/cow/day) in seven 3 x 3 Latin squares to measure the effect of protein protection on milk yield and milk composition. Additional animals fitted with oesophageal and rumen fistulae were used to determine composition of the diet selected and rumen characteristics on three treatments.Cows ingested herbage containing 20% crude protein with a protein solubility of 40%. The untreated casein supplement increased milk yield by 3%, fat 5% and protein 2·4%. Formal-casein produced 20% (3·3 kg/day) more milk than the control, a 13% higher yield of butterfat and 27% more protein. Rumen ammonia concentrations in the afternoon were similar for the control and formal-casein supplemented cows (21 and 23mg/100ml) but significantly higher when casein was fed (74 mg/100 ml) indicating extensive deamination of the untreated protein.Yields of C4–C16 fatty acids in milk fat were 8 and 21% higher for the casein and formal-casein treatments than for the controls, which together with the higher live weight of formal-casein supplemented cows indicated that the milk yield response to the protein supplements was mainly due to a higher daily intake of herbage.