scholarly journals Kinetic aspects of calcium metabolism in lactating sheep offered herbages with different Ca concentrations and the effect of protein supplementation

1989 ◽  
Vol 61 (1) ◽  
pp. 45-58 ◽  
Author(s):  
J. S. Chrisp ◽  
A. R. Sykes ◽  
N. D. Grace
Keyword(s):  
White Clover ◽  
Calcium Metabolism ◽  
Lolium Multiflorum ◽  
Kinetic Studies ◽  
Protein Supplementation ◽  
Relative Contribution ◽  
Protein Status ◽  
Rate Of Absorption ◽  
The Subject ◽  
Protein Supply

1. Two experiments are described in which kinetic aspects of calcium metabolism were studied in housed lactating sheep consuming different fresh herbage species. The importance of protein supply was also investigated.2. In Expt. 1, two groups (n 4) were offered, ad lib., a freshly cut ryegrass (Lolium perenne L.)-white clover (Trifolium repens L.) pasture containing 5·48 g Ca/kg dry matter (DM). One group was supplemented daily with 100 g protected casein. A third group (n 4) was offered, ad lib., freshly cut oats-Tama ryegass (Lolium multiflorum L.) herbage which had a lower Ca content of 3·07 g Ca/kg DM. Stable Ca and nitrogen balances were carried out during the first 7 weeks of lactation. At this stage 180 μCi45Ca were administered for Ca kinetic studies.3. In Expt 2, eight sheep were offered, ad lib., a fresh ryegrass–white clover pasture, and paired on the basis of their udder size. One member of each pair was supplemented daily with 100 g casein via the abomasum and the amount of milk removed was equalized between pairs. Ca and N balances (12 d) and Ca kinetic studies (280 μCi 45Ca) were carried out during weeks 2 and 5 of lactation.4. Rate of absorption of Ca increased, while rate of Ca secretion in milk and resorption from bone decreased as lactation progressed. Ca balances changed from negative to positive as lactation progressed in sheep offered ryegrass–white clover, but, while improving, were always negative in sheep offered oats–Tama ryegrass. Protein supplementation increased (18%) milk production of the ewes in Expt 1 and their retention of N in Expt 2.5. The proportion of utilized Ca derived from the diet, as opposed to the skeleton, tended to increase as a result of protein supplementation.6. Availability of Ca from ryegrass–white clover ranged from 0.19 to 0.32, even though only 50% of the net Ca requirement was derived from the diet. Availability of Ca from the oats–Tama ryegrass diet was similar, though in this case less than 20% of the net Ca requirement was derived from the diet. It was concluded that availability of Ca from forage diets may be lower than previously anticipated.7. Faecal endogenous loss ranged from 16 to 40 mg Ca/kg body-weight per d, and was similar on both diets.8. These and other findings are used to discuss more fully the subject of Ca nutrition in sheep, in particular, the implications of the strong homeostatic control of Ca absorption and the influence of protein status on the relative contribution of the diet and the skeleton in meeting the net Ca requirement of the ewe during lactation.

Calcium metabolism in red deer (Cervus elaphus) offered herbages during antlerogenesis: kinetic and stable balance studies

1987 ◽  
Vol 109 (2) ◽  
pp. 357-364 ◽  
Author(s):  
P. D. Muir ◽  
A. R. Sykes ◽  
G. K. Barrell
Keyword(s):  
Cervus Elaphus ◽  
White Clover ◽  
Maximum Rate ◽  
Calcium Metabolism ◽  
Red Deer ◽  
Kinetic Studies ◽  
The Body ◽  
Ruminant Species ◽  
Antler Growth ◽  
Exchangeable Ca

SummaryKinetic studies of Ca metabolism, using 45CaCl32, were carried out on two mature red deer stags during the period of maximum rate of Ca deposition in the antlers. They were offered green-feed oats to provide energy for maintenance; the diet provided approximately 42mg Ca/kg W per day.Ca appeared to be irreversibly lost from the circulation into the antlers and could be treated for kinetic purposes in the same way as loss of Ca from the body in milk. The size of the rapidly exchangeable Ca pool in the body, excluding the antlers, was 0·21 g/kg W, similar to estimates for lactating cattle. Rates of Ca deposition in the antlers of the two stags, calculated from the model of Ca metabolism, were 58·4 and 38·6 mg Ca/kg W per day. Net endogenous loss was 6–7 mg Ca/kg W per day, much lower than estimates available for other ruminant species. Only 25–40% of Ca requirement or 11–24 mg Ca/kg W per day was derived from the diet, suggesting that the availability of Ca in greenfeed oats is much lower than current estimates for forages. Bones removed on completion of the experiment showed evidence of considerable skeletal demineralization.In other stags subjected to stable Ca balances at the same stage of antler growth, while consuming ryegrass-white clover forage, 60–80% of Ca requirement was derived from the diet, with calculated rates of true absorption of 32–46 mg Ca/kg W per day. These rates of Ca absorption are low compared with values observed in other ruminants at times of high Ca demand such as during lactation.

Chromosomal Patterns of Microsatellite Variability Contrast Sharply in African and Non-African Populations of Drosophila melanogaster

Genetics ◽  
2002 ◽  
Vol 160 (1) ◽  
pp. 247-256
Author(s):  
M Kauer ◽  
B Zangerl ◽  
D Dieringer ◽  
C Schlötterer
Keyword(s):  
Chromosomal Polymorphism ◽  
Background Selection ◽  
Selective Sweeps ◽  
X Chromosomes ◽  
Evolutionary Forces ◽  
Relative Contribution ◽  
African Populations ◽  
Neutral Variation ◽  
Colonization Process ◽  
The Subject

Abstract Levels of neutral variation are influenced by background selection and hitchhiking. The relative contribution of these evolutionary forces to the distribution of neutral variation is still the subject of ongoing debates. Using 133 microsatellites, we determined levels of variability on X chromosomes and autosomes in African and non-African D. melanogaster populations. In the ancestral African populations microsatellite variability was higher on X chromosomes than on autosomes. In non-African populations X-linked polymorphism is significantly more reduced than autosomal variation. In non-African populations we observed a significant positive correlation between X chromosomal polymorphism and recombination rate. These results are consistent with the interpretation that background selection shapes levels of neutral variability in the ancestral populations, while the pattern in derived populations is determined by multiple selective sweeps during the colonization process. Further research, however, is required to investigate the influence of inversion polymorphisms and unequal sex ratios.

scholarly journals Studies on antagonism.―I. The effect of the presence of salts of monovalent, divalent, and trivalent kations on the intake of calcium and ammonium ions by potato tuber tissue

1933 ◽  
Vol 112 (778) ◽  
pp. 451-472 ◽  
Keyword(s):  
Chemical Analysis ◽  
Physical Properties ◽  
Absorption Rate ◽  
Initial Rate ◽  
Final Position ◽  
Ammonium Ions ◽  
Conductivity Method ◽  
Tuber Tissue ◽  
Rate Of Absorption ◽  
The Subject

The intake of salts by storage tissues has been worked out at some length by Stiles using both the conductivity method and chemical analysis to determine the alteration in concentration of the solution supplied to the tissue. Results of these investigations as well as those of other workers on the subject point to the fact that salts are not taken in as such, but as their constituent ions, which may be absorbed to a very different degree. Stiles (1924) found that the ions were absorbed comparatively rapidly at first, for a period lasting up to 10 hours, after which there was a gradual falling off in the absorption rate so that after 24 hours absorption was only proceeding very slowly. It was also suggested that the initial rate of absorption depended more on the physical properties of the ions, such as their mobility and the coefficients of diffusion of their salts, and bore, it was found, no relationship to the final position of equilibrium (Stiles, 1919).

Effects of forage type and protein supplementation on voluntary intakes and particle breakdown of forages by dry dairy cows

1998 ◽  
Vol 1998 ◽  
pp. 207-207
Author(s):  
R.J. Dewhurst ◽  
D.W.R. Davies ◽  
W.J. Fisher ◽  
I.J. Thomas ◽  
A.T. Adesogan
Keyword(s):  
Close Association ◽  
Primary Objective ◽  
Protein Supplementation ◽  
Residual Effects ◽  
Dry Period ◽  
Particle Size Reduction ◽  
Holstein Friesian ◽  
Forage Intake ◽  
Forage Type ◽  
Protein Supply

There is now considerable evidence of residual effects of both energy and protein supply during the dry period on performance in the next lactation. Changes in forage intake and eating/rumination behaviour in the dry period have been implicated in predisposition to metabolic disorders in the subsequent lactation. In particular, there is a close association between intake either side of calving (Grummer, 1995). The primary objective of this experiment was to identify the effects, and interactions, of pre-partum energy and protein supply on forage intake and particle size reduction (as an index of rumination behaviour) of cows in the dry period.Fifty-two Holstein-Friesian cows, calving from September to November 1996, were used in a continuous design experiment The cows were dried off 8 weeks before their anticipated calving date and grazed on bare pasture for one week before training to use Calan gates (using grass silage only).

Muscles versus bones: catfishes as a case study for a discussion on the relative contribution of myological and osteological features in phylogenetic reconstructions

2004 ◽  
Vol 54 (4) ◽  
pp. 373-391 ◽  
Author(s):  
Rui Diogo
Keyword(s):  
Morphological Variation ◽  
Phylogenetic Trees ◽  
High Reliability ◽  
Phylogenetic Analyses ◽  
Data Sets ◽  
Large Set ◽  
Relative Contribution ◽  
Phylogenetic Reconstructions ◽  
The Subject

AbstractThe levels of homoplasy and phylogenetic reliability of different types of data sets have since long intrigued evolutionary scientists. This paper provides, to the author's knowledge, the first assessment of the relative contribution of a large set of myological and osteological characters in simultaneous phylogenetic analyses. The biological taxon used as a case study for this comparison was the highly diverse and cosmopolitan teleost Siluriformes (catfishes) which, with 34 families, about 437 genera and more than 2700 species, represents about one third of all freshwater fishes and one of the most diverse vertebrate groups. Such a direct comparison of the relative contribution of these two types of data sets has the advantage that the homoplasy levels and the phylogenetic trees being compared refer to the same group and, more importantly, to the very same terminal taxa. The overall analysis of the results presented in this work seems to indicate that: (1) osteological structures display a greater morphological variation than myological ones; (2) this difference (which is very likely overenhanced by the fact that the phylogenetic variation of osteological structures has historically been the subject of many more studies and descriptions than myological ones) is particularly notable in small taxa, such as genera or species; (3) myological characters provide, however, a high proportion of informative characters for disclosing the relationships between larger taxa, and, thus, for disclosing the phylogeny of the higher clades in which these taxa are included. These results raise some puzzling, general questions. For instance, what are the reasons for the seemingly greater morphological variation of osteological structures? And why is this greater morphological variation of osteological structures in relation to myological structures particularly pronounced in low ranking taxa? Does natural selection eventually act, in certain cases, more on bones than on muscles? Is the development of myological structures eventually more constrained than that of osteological features? What explains the apparently high reliability of muscular characters to disclose the higher-level phylogeny of higher taxa? More direct comparisons, either of other major groups of teleosts or of vertebrates in general, are clearly needed to infer if the patterns found in the direct comparison of this work correspond to a more general phylogenetic pattern, or instead refer to a particular situation found in the order Siluriformes.

Degradability of crude protein from clover herbages used in irrigated dairy production systems in northern Victoria

2001 ◽  
Vol 52 (3) ◽  
pp. 415 ◽  
Author(s):  
D. C. Cohen
Keyword(s):  
Protein Content ◽  
White Clover ◽  
Crude Protein ◽  
Nutritive Value ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Crude Protein Content ◽  
Persian Clover ◽  
Protein Supply ◽  
In Sacco

An in sacco (nylon bag) technique was used to estimate the degradability of dry matter (DM) and crude protein, and to estimate the effective rumen degradability of protein (ERDP), for 3 irrigated clover herbages. Pasture characteristics (nutritive values and leaf: stem ratios) were also described, and relationships to ERDP established. The nutritive value characteristics and degradabilities of white clover (Trifolium repens L.), Persian clover (Trifolium resupinatum L.), and subterranean clover (Trifolium subterraneum L.) were also compared for various regrowth periods (of 3, 4, 6, and 12 weeks). Nutritive value characteristics of clover herbages varied from 9.9 to 11.9 MJ/kg DM for metabolisable energy, 153 to 304 g/kg DM for crude protein, and 209 to 377 g/kg DM for neutral detergent fibre. The leaf: stem ratio correlated well with the crude protein content of the clovers, with herbages consisting of more leaf generally having superior crude protein content (R2 = 0.64, P < 0.001). The effective rumen degradability of protein for clover herbages ranged from 60 g/kg DM for mature (12 week regrowth) subterranean clover to 195 g/kg DM for vegetative (3 weeks regrowth) Persian clover. For clover herbages with a 3-week regrowth period, after initial cutting to 5 cm, and at ruminal outflow rates of 0.08/h, the effective rumen degradability of protein varied from 136 to 195 g/kg DM. A positive relationship between crude protein and ERDP (R2 = 0.82) suggested that ERDP could be estimated for clover herbages that have been previously assessed for crude protein content, obviating the need for in sacco studies. Calculated degradabilities were lower for all clovers when higher ruminal outflow rates were assumed. Using the metabolisable protein system, metabolisable protein supply and metabolisable protein in excess of animal requirements were calculated. Ruminal losses of nitrogen were also estimated for cows consuming white clover of varying regrowth periods in both early and late lactation. It was concluded that metabolisable protein supply is unlikely to limit production in these examples. At regrowth periods of 3 weeks, metabolisable protein contributions from microbial and dietary sources were similar, and twice that required by the animal. Ruminal losses of nitrogen were substantial and amounted to 66—23% of nitrogen intake. In the experiments reported here, if all of the energy required to excrete excess protein (as urea) could instead be used for the production of milk, cows may have produced 0.5mp;mdash;2.0 kg more milk per day. Such losses could potentially be reduced if the protein content and/or degradabilities of clover herbages were reduced, and/or energy rich supplements were offered.

scholarly journals MANAGEMENT OF COVER CROPS FOR WEED CONTROL BETWEEN PLASTIC MULCH IN PEPPERS (CAPSICUM ANNUUM)

HortScience ◽  
1993 ◽  
Vol 28 (4) ◽  
pp. 257E-257
Author(s):  
Francis X. Mangan ◽  
Mary Jane Else ◽  
Stephen J. Herbert
Keyword(s):  
White Clover ◽  
Cover Crops ◽  
Cover Crop ◽  
Lolium Multiflorum ◽  
Field Research ◽  
Soil Surface ◽  
Winter Rye ◽  
Weed Species ◽  
Plastic Mulch ◽  
Crop Species

Field research was conducted in Deerfield, Mass. to study the effects of different cover crop species seeded between plastic mulch on weed pressure and pepper yield. A complete fertilizer was applied before plastic was laid on Sept. 13, 1991. Two cover crop treatments were seeded Sept. 13, 1991: white clover (Trifolium repens) alone and hairy vetch (Vicia villosa) in combination with winter rye (Secale cereale). On May 27, 1992 the vetch and rye were mow-killed with the biomass left on the soil surface. Annual rye (Lolium multiflorum) was then seeded on the same day as the third cover crop treatment. The remaining two treatments were a weedy check and a hand-weeded check. Peppers were transplanted into the plastic on May 31. Both the annual rye and clover were mowed three times over the course of the experiment with the biomass left between the plastic mulch. The white clover and annual rye were much more competitive with weed species than the dead mulch of vetch and rye. The three cover crop treatments had pepper yields that were severely depressed compared to the hand-weeded treatment. Among the three cover crop treatments, only the annual rye yielded more peppers than the weedy check.

scholarly journals Efficacy of several organic herbicides and glyphosate formulations under simulated rainfall

2005 ◽  
Vol 58 ◽  
pp. 157-163 ◽  
Author(s):  
T.K. James ◽  
A. Rahman
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Dry Matter ◽  
Lolium Multiflorum ◽  
Simulated Rainfall ◽  
Annual Ryegrass ◽  
Plant Type ◽  
Test Species ◽  
Elytrigia Repens ◽  
Glyphosate Formulations

Glasshouse studies were conducted to determine the efficacy and rainfast interval of several organic and glyphosatebased herbicides marketed for use in home gardens The test species used were white clover (Trifolium repens) annual ryegrass (Lolium multiflorum) and couch (Elytrigia repens) After spraying the 6weekold plants some pots were set aside and received no simulated rainfall while others were placed under the rainfall simulator (11 mm rain over 30 minutes) at 2 3 or 6 h after application Plants were visually assessed for herbicide efficacy and after 4 weeks all the new growth was harvested and dry matter measured Rainfall applied 2 or 3 h after application did not reduce the efficacy of organic herbicides In the case of glyphosate rain applied at 2 h after spraying reduced efficacy by 440 while rain 6 h after application reduced it by 020 depending on formulation and plant type

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