Research Article
Developmental changes in beef steers as influenced by fattening, age and type of ration
- H. C. Luitingh
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- 27 March 2009, pp. 1-47
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1. The effect of fattening, age and the ratio of concentrates to roughage in a ration on the development of beef steers was investigated. The specific purpose was to study developmental patterns during the short-term fattening of beef steers of different ages in order to ascertain to what extent beef steers improved in the proportions of the various body parts, offals, organs and tissues.
2. The experimental material consisted of 104 beef steers of three age-groups, namely, ± 8, ± 20 and ± 32 months old, fed on rations differing in the ratio of concentrates to roughage and 36 control steers of the same age-groups, slaughtered at the start of the experiment.
3. When the weights of the parts of the carcasses were expressed as a percentage of the carcass weight, it was found that with the exception of a few parts, the percentage which the parts constituted of the carcass remained remarkably constant in the various groups. The effect of age in both the fattened and unfattened groups was comparatively small, whilst the effect of fattening was of slightly greater magnitude. The effect of the ration concentration per se was negligible.
4. The parts where fat was deposited formed a significantly (P < 0·01) larger percentage of the carcass of the fattened than of the unfattened steers (kidney and channel fat, thin flank and cod, brisket, plate and neck).
5. The shoulder, chuck and buttock and rump, formed a significantly (P < 0·01) lower percentage of the carcasses of the fattened than of the unfattened steers.
Protein-bound iodine, erythrocytes and haemoglobin in the blood of beef steers and their relation to rate of gain
- H. C. Luitingh
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- 27 March 2009, pp. 287-290
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The serum protein-bound iodine concentration in the blood of beef steers varied between animals and was not correlated with the daily gain during the fattening period. The data, however, are insufficient to arrive at a definite conclusion.
The average erythrocyte counts of the blood were 7·86 (range: 5·89–8·75), 8·59 (range: 6·55–10·15), and 8·54 (range: 5·23–9·62) million per mm.3 for steers of 14, 26 and 38 months of age. The difference between the counts of the yearlings and that of the other age groups was statistically significant. The red cell fraction increased with live weight over the range 700–1230 lb. Although a significant (P < 0·01) correlation was found between the number of erythrocytes in the blood and the daily gain of the steers, the erythrocyte count cannot be employed to predict the possible gaining ability of single beef animals.
The haemoglobin content of the blood was found to be 14·02 (range: 9·8–17·4) in the case of the yearlings, 14·68 (range: 11·8–18·5)and 14·61 (range: 7·95–16·85) g./100 ml. blood in the case of the 2-year-olds and 3-year-olds respectively. These differences between age groups were not significant.
A correlation of 0·31 was found between the haemoglobin content and live weight of steers within the weight range of 600–1230 lb. The data suggest that for every 100% increase in weight, the haemoglobin in the blood increased by 17%. No correlation was found between the haemoglobin content and the rate of gain of the steers.
Loss of mineral nitrogen from soil
- K. Shaw
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- 27 March 2009, pp. 145-152
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1. The pattern of downward movement of nitrate in light soil is different from that in heavy clay soil of the kind used in this work.
2. In light sandy soils, where vertical structural fissures are absent, nitrate becomes distributed down the profile on leaching.
3. In heavy soils, which are well fissured and possess a gleyed horizon of partially decomposed plant debris at cultivation depth, most of the nitrate disappears from the profile after removal, by leaching or denitrification, from the cultivation layer.
4. There is little difference in the amount of rain required to remove nitrate from the surface layers of light or heavy soil.
5. Heavy and continuous rain is required to remove nitrate completely from either light or heavy soils.
6. Nitrification of ammonium sulphate is more rapid in summer than winter, but nitrification does proceed slowly during winter.
7. Ammonium nitrogen is not leached from the surface layer of either light or heavy soil.
The growth of the alimentary tract of the fowl and the goose
- E. G. Hallsworth, J. I. Coates
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- 27 March 2009, pp. 153-163
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A study has been made of the internal volume of the different parts of the alimentary tract of geese and fowls.
It has been shown that although the adult geese were two or three times as heavy as the adult fowls, the mean total gut capacity, exclusive of the crop, was proportionately less. Although the gizzard was much greater in weight than in the fowl, its capacity in proportion to body weight is only half that of the fowl, whilst the caeca are relatively even smaller. The distended oesophagus of the goose, which replaces the crop of the fowl, was at all times smaller relative to body weight.
The gut capacities of both chicks and goslings increased rapidly when they began to feed, and reached a maximum, relative to body weight, within the first fortnight after hatching. At 16 weeks, the capacity of the alimentary canal had almost the same relation to body weight as in the adult.
In both, the small intestine constitutes the major proportion of the volume in the adult, being 33–40% in the fowl and more than 50% in the goose.
Feeding a diet containing 21% crude fibre and supplemented with procaine penicillin G produced chicks with relatively greater gut capacities, and this effect was enhanced by the concurrent inclusion of procaine penicillin G, but where the fibre was reduced to 17·4%, the gut capacities were not significantly different, in relation to body weight, than in the control group.
Histological examination of the wall of the gut of chickens raised on different diets showed marked abrasion on high-fibre diets, and a much thinner intestinal wall in those birds receiving antibiotic.
The weight of the thyroid and pituitary glands and its relationship with rate of gain in beef steers
- H. C. Luitingh
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- 27 March 2009, pp. 291-294
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The daily live-weight gain of beef steers was not correlated with the weight of the pituitary gland. In the case of the thyroid gland a significant correlation was found between the absolute weight of the gland and the rate of gain. No correlation, however, was found between the relative weight of the thyroid gland and the rate of gain of the steers.
A highly significant correlation was found between the weight of both the pituitary and thyroid glands and the live weight of the steers (r = 0·44 and r = 0·55 respectively), and the slope of the regression lines showed that the weight of the pituitary gland varied with the power of 0·34 of live weight (0·34% increase in the weight of the pituitary for every 1% increase in live weight) whilst the weight of the thyroid gland varied with the power of 0·89 of the live weight.
No correlation was found between the weight of the pituitary and thyroid glands. The average weight of the pituitary was 1·89, 2·11 and 2·19 g. and the average weight of the thyroid was 16·81, 20·24 and 22·65 g. for steers of 14, 26 and 38 months respectively. The average live weights of the steers in the age groups concerned were 791, 893 and 1071 lb. respectively.
The apparent digestibility of the non-nitrogenous fraction of pig feeds
- J. Glover, H. W. Dougall
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- 27 March 2009, pp. 49-51
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A simple method for the estimation of the digestible non-nitrogenous fraction of normal pig feeds is described. It requires only knowledge of the digestibility coefficient of the crude protein contained in the dry matter of the feed.
More accurate estimates can be obtained by applying to this method a simple correction involving only the crude protein content of the dried feed. Attention is drawn to the intimacy of the relationship between the digestibilities of the non-nitrogenous and nitrogenous components of the diet.
Liquid manure as a grassland fertilizer. I. The response to liquid manure and to dry fertilizer
- M. E. Castle, A. D. Drysdale
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- 27 March 2009, pp. 165-171
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1. A small-scale plot experiment was conducted for a 3-year period, 1958–60, to study the comparative effect of applications of liquid manure, water and dry fertilizer on the yield and quality of an established meadow fescue and white clover sward.
2. The liquid manure was collected from a cowshed and contained on average 0·23% N, 0·003% P2O6 and 0·48%K2O.
3. The treatments applied each year were: (1) control, no fertilizer; (2) and (3) a low and a high rate of water equal in weight to the liquid manure applied in treatments (4) and (5) respectively; (4) a low rate of liquid manure supplying 75 lb. nitrogen and 159 lb. K2O; (5) a high rate of liquid manure supplying 150 lb. nitrogen and 318 lb. K2O/acre; (6) and (7) liquid manure as in (4) and (5) plus 82 lb. P2O6/acre; (8) a low rate of normal dry fertilizer supplying 87 lb. nitrogen, 82 lb. P2O6 and 84 lb. K2O/acre; and (9) a high rate supplying 174 lb. nitrogen, 82 lb. P2O5 and 168 lb. K2O/acre.
All treatments were applied in five equal dressings each year, one for each cut, except the P2O5 which was applied twice a year.
4. The yields of herbage dry matter and crude protein were not affected by the water treatments, but both the liquid-manure and dry-fertilizer treatments caused significant increases in yield. The application of phosphate on the liquid-manure treatments had no significant effect on yields.
5. The crude-protein contents of the herbage on the different treatments did not show any large or consistent differences.
6. The botanical compositions of the swards were significantly different at the end of the third experimental year. On the liquid-manure treatments the content of clover had increased and the meadow fescue and dicotyledonous weeds decreased compared with the control. The mean content of clover in the swards at the end of the trial was 32, 18 and 15% on the liquid-manure, dry-fertilizer and control treatments respectively.
7. There were no major differences between either the pH values or the contents of P2O5 in samples of soil on the different treatments after 3 years, but the average K2O value on the control and two water treatments was almost half that on the high liquid-manure treatment.
8. The mineral contents of the herbage were determined. In 2 of the 3 years the liquid-manure treatments produced herbage with high K and lowered Ca, Mg and Na contents. The Mg content of the herbage on the four liquid-manure treatments averaged 0·26%.
Comparative studies of meat. VIII. The percentage of fat in the fatty and muscular tissues of steers and the iodine number of the extracted fat, as affected by breed and level of nutrition
- E. H. Callow
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- 27 March 2009, pp. 295-307
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1. An investigation has been carried out concerning the percentage of fat in the subcutaneous and intermuscular fatty tissues and in the muscular tissues, and the iodine number of the extracted fat from eight anatomical joints (foreshin, neck, shoulder, thorax, loin, pelvis, leg and hindshin) and from the perinephric fatty tissue and psoas muscles of the carcasses from twenty-four animals. The animals were from three breeds (Hereford, Dairy Shorthorn and Friesian) and were on four levels of nutrition—high-high and medium-high, and high-medium and medium-medium. The first two groups—finished on concentrates—were younger than the second two groups—finished on grass.
2. Using an analysis of variance for the resultant data for percentage of fat and iodine number, it was found that breed had affected the percentage of fat in the tissues of the various joints significantly—on the average the order was Shorthorn (highest), Hereford and Friesian (lowest). This result could be predicted from the fact that this was the order of fatness of the carcasses (as measured by the percentage of fatty tissue in the carcass—see Callow, 1961).
3. The data for iodine number showed no significant effect for breed in either the subcutaneous or intermuscular tissues. The significant effect of breed in the case of muscle could be attributed to significant differences in the overall level of fatness (see Callow, 1961) of the carcasses of the three breeds.
4. A good correlation existed between the average percentage of fat in a joint and the average iodine number of fat extracted when the data for various joints was used to calculate straight lines of best fit. (In the case of muscular tissue, it was necessary to use the inverse of the percentage of fat to calculate the average—because the relation between the percentage of fat in muscular tissue and its iodine number is a rectangular hyperbola.)
5. Using such lines of best fit, it was possible to show that certain joints had tissues which gave abnormal values for iodine number. Thus, deepseated tissues, like psoas muscle and kidney fat, had unexpectedly low values, whilst tissues from the hindshin had unexpectedly high values. This was attributed to the effect of local temperature—a high local temperature in the body giving a lower iodine number and a low temperature a higher iodine number than would otherwise be expected. The special case of subcutaneous fat from the thorax—with a higher iodine number than expected—is explained by the presence of brisket fat (which has a high iodine number).
6. The data were used graphically to show the effect of growth gradients, thus the average percentage of fat in all the tissues is lowest in fore- and hindshins and highest in thorax (muscular and intermuscular tissues) and in the pelvis (subcutaneous tissue). Similar effects, but in the reverse direction, were shown by average values for iodine numbers.
7. There were systematic differences in the percentage of fat in the subcutaneous and intermuscular tissues of joints and in the iodine number of the extracted fat. These too showed marked growth gradients. Although the percentage of fat in the intermuscular tissue was greater than that in the subcutaneous tissue in the fore- and hindshins, it was less in the thorax, loin, pelvis and leg. In spite of this, the iodine number of the subcutaneous fat was always higher than that of the intermuscular fat. This is attributed to the former being a colder tissue than the latter.
8. It was shown that the relation between iodine number and percentage of fat in the various joints was different for the animals finished on grass (highmoderate and moderate-moderate levels of nutrition) as compared with those finished on concentrates (high-high and moderate-high levels). This was attributed to the rate of fattening being greater in the second case and to this giving rise to lower iodine numbers.
9. Beyond this effect of rate of fattening, no reason could be found for the fact that the general level of iodine numbers showed variation from animal to animal.
10. The extreme variation in percentage of fat in the tissues was (a) muscular tissue from 1·3 to 14·5%, (b) intermuscular tissue from 29·5 to 82·7%, and (c) subcutaneous tissue from 25·2 to 89·8%. For iodine number the variation was (a) 50·0 to 73·9, (b) 42·9 to 67·9 and (c) 46·3 to 67·9 It is thus clear that beef can be a very variable foodstuff.
The effect of rainfall and age on the yield of some unfertilized fodder crops in Kenya
- J. Glover, W. R. Birch
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- 27 March 2009, pp. 53-57
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Five perennial fodder crops and maize were grown for 11 years or more in unfertilized soil. The effect of rainfall, annual and seasonal, and age from planting was examined in detail. Increased rainfall, whether annual or seasonal, led to increased yields of all crops, although the extent of the increase depended on the type of crop, the nature of the rainy season, whether long or short, and in particular the age of the perennial crops. All the perennials aged at similar rates and ageing led to reduced yields. The depressing effect of age is thought to be due to overcrowding and possibly a concealed loss of fertility.
Fibre shedding and fibre-follicle relationships in the fleeces of Wiltshire Horn × Scottish Blackface sheep crosses
- J. Slee, H. B. Carter
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- 27 March 2009, pp. 309-326
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1. Changes in fleece structure produced by crossing the Wiltshire Horn and Scottish Blackface breeds of sheep have been analysed. Skin and fleece samples were available from lambs and adults of both parental breeds, and from the F1 F2 and back-cross genotypes. For the analysis, three types of fibre: kemps, hairs (both primaries) and secondary fibres were distinguished.
2. The frequency of kemp fibres was high in the Wiltshire and relatively low in the Blackface. The frequency of hair fibres was nil in the Wiltshire and fairly high in the Blackface. The crosses were intermediate between the parents. Despite these fibre type changes among the primary fibres there was no difference between the breeds or crosses in follicle population densities or in the relative proportions of primary and secondary follicles.
3. Kemp fibres were shorter and finer in the Wiltshire than in the Blackface. In the crosses they were intermediate. Hairs, when present in the crosses, were shorter and finer than in the Blackface. Secondary fibres were shorter in the Wiltshire than in the Blackface but in some of the crosses they were at least as long as in the Blackface. Wiltshire secondary fibres were remarkably coarse and strongly medullated and this notable characteristic was carried over to some extent in the crosses. Throughout the study comparison in these terms was always complicated by fibre shedding.
4. Fibre shedding was universal for all types of follicle in the Wiltshire. In the Blackface, primary central follicles appeared to shed their kemp fibres two or three times yearly. For hairs and secondary fibres shedding did not occur more than once per year and the frequency of shedding amongst these fibres was low. In the crosses the frequency of shedding in kemps and the incidence of shedding in hairs and secondaries were higher than in the Blackface. Increases in the incidence and frequency of shedding probably had some effect in decreasing the measurable fibre length in the crosses.
5. The mean length and diameters of the different fibre types were usually positively correlated within sheep. In this and other ways there was not much evidence of competition for fibre substrate between the different types of mature follicles, in this material.
6. Birth-coat classifications distinguished between the typically smooth Wiltshire and the hairy Blackface birth-coats. Birth-coats in the crosses were intermediate but showed partial dominance of the hairy type.
7. The most important of the observed changes in fibre and follicle morphology can be briefly summed up by considering how the Blackface phenotype was modified in the crosses by the introduction of the Wiltshire genotype, viz.
(a) The proportion of kemps was increased at the expense of hair fibres. This was brought about by kemp fibres tending to replace hairs in all primary central and in some primary lateral follicles.
(b) All primary fibres were diminished in length and thickness; secondary fibres increased in thickness. The general fibre population therefore became more uniform.
(c) The shedding frequency of kemps and the shedding incidence among hairs and secondaries were both increased.
(d) Follicle population density, follicle group structure and the S/P follicle ratio were unaltered.
(e) The degree to which changes occurred in the different crosses was generally proportional to the percentage of Wiltshire-derived genes present.
8. The fact that the relative frequencies of kemp and hair fibres could be altered without any concomitant changes in the follicle group pattern showed that a particular follicle type was not a priori bound to produce a particular fibre type. It seems clear therefore that the physiological activity of follicles can be altered genetically whilst their organization within the follicle group pattern remains invariant.
A new procedure for studying the release and fixation of potassium ions in soil
- B. C. Matthews, P. H. T. Beckett
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- 27 March 2009, pp. 59-64
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The relationship between the exchangeable potassium content of a soil and the activity ratio, aK/√(aCa+Mg), of the solution with which it is in ‘instantaneous equilibrium’ is a characteristic of the soil which is independent of the soil: solution ratio or the total electrolyte concentration (up to O·06 M) of the solution. It is unaffected by the transfer of substantial amounts of potassium ions to or from the fixed state. Hence instantaneous equilibrium curves provide a basis against which to measure the changes in exchangeable potassium content due to fixation and release. This procedure has the important advantages that all measurements are made in the solution phase and that the solutions in contact with the soil approximate to the natural soil solution.
The technique has been employed successfully in studying the fixation and release of potassium by several widely different soils.
The results confirm that fixation or release are determined by the extent to which the soil contains more or less exchangeable potassium than its equilibrium percentage potassium saturation. Seemingly the equilibrium percentage potassium saturation, and hence the equilibrium activity ratio of potassium in the soil solution aK/√(aCa+Mg), is regulated by the amounts or proportions of potassium in the fixed state. The amounts or proportions of potassium in the fixed state may be increased by repeated applications of potassium fertilizers and reduced by continued cropping.
The utilization of Hyparrhenia veld for the nutrition of cattle in the dry season III. Studies on the digestibility of the produce of mature veld and veld hay, and the effect of feeding supplementary protein and urea
- C. A. Smith
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- 27 March 2009, pp. 173-178
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Indigenous (Bos indicus) oxen fed ad lib. were used to measure the changes in the apparent digestibility of mature Hyparrhenia veld during the dry season, and also the apparent digestibility of late-cut veld hay and nitrogen-fertilized veld hay. The forages were those used in a field trial, and the present results complement previous work.
1. Mature Hyparrhenia veld harvested at the end of the rains as veld hay or green forage, contains approximately 50% digestible o.m. and 0·6% digestible c.p. The low level of approx. 3% c.p. resulted in a low apparent c.p. digestibility and consequent protein deficiency.
2. The nutritive value of the mature Hyparrhenia grassland as ‘standing hay’ progressively dropped to 38% digestible o.m. and negative c.p. digestibility by mid-dry-season in July.
3. There was an accompanying decline in voluntary intake of forage from approximately 12 lb. d.m./1000 lb. animal/day at the end of the rains to 8 lb. d.m./1000 lb. animal/day in mid dry season.
4. The seasonal drop in digestibility values is accentuated by the drop in dry-matter intake so that a diet of mature veld herbage in mid dry season is grossly deficient in both energy and protein.
5. The feeding of supplementary protein or urea resulted in a 40–60% increase in the intake of mature Hyparrhenia forage. Urea and groundnut meal were of equal value in their effect on herbage intake at the level of feeding used in this trial.
6. The main factor limiting the utilization of the mature Hyparrhenia veld appears to be a dietary protein deficiency. Increasing the dietary protein level, either by using nitrogen fertilizers to raise the herbage crude protein, per cent, or by supplementary feeding of protein or urea, not only relieved the dietary protein deficiency, but, due to the resultant increase in forage intake, also corrected the deficiency in dietary energy. The nutritive value of mature Hyparrhenia forage was thus raised from a submaintenance to a supra-maintenance level.
Development of penis and sheath in young dairy bulls, and its relationship to age and body weight
- B. R. Ashdown
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- 27 March 2009, pp. 65-69
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1. Eighty-six bull calves (fifty-two Friesian, twenty-two Ayrshire, twelve Shorthorn) were examined at intervals, during the first year of life, by a method which allowed classification of the degree of adherence between penis and sheath into five classes.
2. Mean age and weight at which separation between penis and sheath commenced and was completed are recorded for each breed. Significant breed differences were found.
3. The rate of separation accelerates as development proceeds.
4. The relationships between age, body weight, and commencement and completion of separation in the Friesian bulls are analysed by correlation methods. These analyses suggest that both age and body weight are important in sexual development.
5. An equation is given for the linear regression of age at completion of separation on age and weight at commencement of separation and weight at 10 weeks for the Friesian bulls.
The prediction of monthly rainfall as exemplified by data from south-east England
- D. A. Holland
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- 27 March 2009, pp. 327-331
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A study is made of 46 years' records of rainfall for each of the months April to September. Following the determination of the distribution of monthly rainfall recommendations are made as to the best method of specifying rainfall and of predicting the rainfall to be expected on the basis of previous observations.
The energy requirements of sheep for maintenance and gain. I. Pen fed sheep
- I. E. Coop
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- 27 March 2009, pp. 179-186
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Four experiments have been conducted with sheep, housed and fed in pens, to determine the maintenance and live-weight gain requirements of sheep under such conditions.
1. Fifteen Corriedale sheep of initial live weight 115 lb. were fed at maintenance for 13 weeks. Daily DOM (digestible organic matter) requirement for maintenance was 0·92 ± 0·07 lb.
2. Twelve Romney ewes of mean live weight 106 lb. over the period were fed for 5 months, six on submaintenance and six on super-maintenance levels. Daily DOM requirement for maintenance was 0·99 ± 0·05 lb., and requirement for gain 2·29 ± 0·20 lb. DOM per lb. gain or loss.
3. Thirteen Romney ewes of mean live weight 110 lb. over the period were fed at sub- and supermaintenance levels for 8 weeks yielding the result: daily DOM intake for maintenance 1·04 ± 0·13 lb. and for gain 2·25 ± 0·24 lb. DOM per lb. gain.
4. Twenty-four Romney ewes of initial live weight 107 lb. were randomized into five groups and fed fresh grass, dried grass, sheep pellets, lucerne hay and rye-grass straw for 11 weeks at slightly below maintenance. There were no significant differences between groups and the mean estimate of maintenance was 1·00 ± 0·11 lb. DOM per day.
Converting these estimates to those of a 100 lb. sheep using the ¾ power of live weight, and then taking the mean gives the final estimate for maintenance of a 100 lb. sheep 0·92 lb. DOM, 0·96 TDN or 0·89 lb. SE.
Adherence between penis and sheath in beef calves at the time of castration
- R. R. Ashdown
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- 27 March 2009, pp. 71-72
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1. 247 commercial beef calves were examined at ages ranging from 0–13 months.
2. Separation between penis and sheath commenced at about 3 or 4 months and was completed at about 9 or 10 months. Great differences were, however, found between animals of similar ages.
3. The degree of adherence present at castration was greater than that found in a previous survey at the time of slaughter. Evidence is presented to support the suggestion that separation between penis and sheath may take place after castration.
Comparative nitrogen digestibility in Brahman, Brahman × Shorthorn, Africander × Hereford, and Hereford Steers
- G. C. Ashton
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- 27 March 2009, pp. 333-342
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1. Eight nitrogen metabolism experiments, each with sixteen steers representing grade Brahman, Brahman x Shorthorn, Africander x Hereford and Herefords, were carried out. The steers were fed according to body weight to the power 0·73, on rations consisting of natural pasture hay alone or in combination with lucerne hay.
2. These experiments showed that the steers with zebu blood were significantly superior to the Herefords with regard to dry-matter digestibility and apparent nitrogen digestibility. The breed difference disappeared when nitrogen digestibility was calculated from the relationship feed nitrogen minus undigested faecal residue nitrogen, divided by feed nitrogen.
3. Two further nitrogen metabolism experiments with six Africander x Hereford and four Hereford steers fed natural pasture hay plus lucerne hay, and one experiment with two Brahman x Shorthorn, two Africander x Hereford and two Hereford steers fed chaffed wheat straw were carried out. The steers were fed an equal amount of ration, irrespective of body weight.
4. In these three experiments faecal nitrogen was fractionated into undigested residue nitrogen, non-dialysable centrifugable nitrogen, non-dialysable non-centrifugable nitrogen, and dialysable nitrogen. The breed groups differed significantly in the amount of dialysable faecal nitrogen excreted but not in any other component.
5. The amount of dialysable faecal nitrogen excreted on equal intake was very significantly negatively correlated with body weight (r = −0·807, P < 0·01).
6. It was found that in two experiments the mean difference between Africander x Herefords and Hereford steers, mean body weights 863 and 686 lb., respectively, was 1·81 ± 0·51 g. nitrogen per day. It was calculated that this would represent about 70 ± 20% of the body-weight difference between the breeds if the lost nitrogen was fully utilizable. This agreed well with the estimate of 65% derived from the square of the correlation coefficient.
The energy requirements of sheep for maintenance and gain. II. Grazing sheep
- I. E. Coop, M. K. Hill
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- 27 March 2009, pp. 187-199
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The intake of grazing sheep in terms of digestible organic matter, DOM, has been measured by faecal index methods, employing chromic oxide to measure faecal output and faecal nitrogen for digestibility of pasture. A regression equation for the prediction of digestibility from faecal nitrogen (organic matter basis) was developed from several series of digestibility trials with pasture, the equation being
digestibility of organic matter = 30·84 +
Four trials to measure maintenance and gain were conducted, as follows:
(i) Thirty-eight sheep, comprising twelve wethers of mean weight 112 lb., thirteen small or thin Romney ewes of mean live weight 110 lb. and thirteen large or fat Romney ewes of mean live weight 166 lb. were grazed all together for 17 weeks on a rye-grass-white clover sward at an intensity such that live weight was just maintained. Corrections to intake were made for small live-weight changes.
Daily DOM intake (lb.) for maintenance = 0·062 maintenance for a 100 lb. sheep becomes 1·48 ± 0·08 lb. DOM/day.
(ii) Thirty-six weaned Romney ewe lambs of mean initial live weight 56 lb. were grazed for 8 weeks on a rye-grass-white clover pasture and allowed to gain in weight. Regression of intake on gain gave the equation
daily DOM intake (56 lb. lamb) = 0·93 (±0·07) + 0·90 g
where g = gain in lb./day. Combining this lamb data with that of the previous trial yields the equation
DOM intake (lb.) for maintenance = 0·052
(iii) Forty ewes, comprising eight Southdowns, twelve Romneys, eight Border Leicesters and twelve Border-Romney crossbreds were grazed together on short pasture (rye-grass-white clover) for 12 weeks. The ewes were of widely differing live weight and the mean gains or losses of the groups over the period varied from + 1·5 to −4·5 lb.
Daily DOM intake (lb.) for maintenance = 0·061 which for a 100 lb. sheep becomes 1·63 ± 0·13 lb. DOM.
(iv) Seven Romney ewes were grazed in high and eight ewes in low intake groups for 8 weeks. Regression of intake on gain gave the equation
daily DOM intake (130 lb. ewe) = 1·58 (±0·06) + 1·98 g.
For a 100 lb. sheep this becomes 1·36 (± 0·06) lb. DOM/day for maintenance.
The three estimates of maintenance of a grazing sheep of 100 lb. live weight 1·48, 1·63 and 1·36 lb. DOM/day are greatly in excess of the estimate of 0·92 lb. DOM/day for pen-fed sheep. It is believed that this difference is outside experimental error and represents a true increase in energy cost due to grazing. It is suggested that the cause of this derives from the energy costs of walking and harvesting the pasture together with climatic factors wind, cold and rain. The exponent of live weight agrees well with the estimates of other workers based on pen-fed animals. The energy cost of gain is less than that of pen-fed sheep and it is suggested that this is due to the maintenance cost decreasing with increasing availability of pasture and with increasing gain.
Woburn irrigation, 1951–59 I. Purpose, design and weather
- H. L. Penman
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- 27 March 2009, pp. 343-348
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Part I, largely introductory, outlines the design of an experiment to measure the responses of ordinary farm crops to supplementary irrigation in a part of England where, from meteorological reasoning, the frequency of need was expected to be about 2 years in 3. The watering treatments were based on estimates of potential transpiration, made from weekly weather data collected on the site, and measured rainfall. The basis of the computation is restated, and the balance of rain and estimated transpiration plotted for each of the 9 years, week by week in summer, month by month in winter. The meteorological specification of frequency of need was satisfied in 5 of the years, during which twenty crops were taken. Of these, eighteen responded to irrigation. In the other years, four of the sixteen crops responded positively to irrigation, and a few of the remaining twelve responded negatively when early irrigation was followed by summer rainfall sufficiently in excess to cause leaching from irrigated plots.
The inter-relationships of individual proteins and carbohydrates during fermentation in the rumen of the sheep. II. The fermentation of starch in the presence of proteins and other substances containing nitrogen
- D. Lewis
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- 27 March 2009, pp. 73-79
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1. The inter-relationships of starch and proteins during fermentation in the rumen are measured by estimating volatile fatty acids, ammonia, lactic acid and amino acids after administering the starch and protein supplements alone or together.
2. The presence of casein stimulates the formation of volatile fatty acids from starch. Simpler nitrogen-containing compounds are less effective than casein; other proteins are as effective as casein provided they are fermented as rapidly in the rumen.
3. Proteins can be divided roughly into three groups on the basis of the rapidity with which they give rise to ammonia in the rumen: casein, gelatin, ground nut protein > soy protein, wheat gluten > bovine albumin, zein.
4. The proportion of acetic acid falls and of propionic acid and higher acids rises as proteins that are rapidly fermented are placed in the rumen.