bluuebunny/crossref_metadata_2025 huggingface dataset:
Identical twins and developmental stability
Authors: Taylor C. S.
Published: September 2010

1. The stability with which dairy cattle develop in body size up to 2 years of age was studied in 60 pairs of uniformly treated identical twins, i.e. an assessment was made of the influence of season, genotype, mean size of twin pair, age and degree of maturity on the level of within-pair variability.

2. The frequency distributions of size differences shown by one-egg twins were in many cases decidedly leptokurtic.

3. The similarity in size of the identical twins studied was only slightly, if at all, influenced by season. Within-pair variability under free outdoor grazing was certainly not any greater than under semi-controlled conditions indoors.

4. The stability with which cattle grew appeared to depend on their genotype. Identical twins of the Shorthorn breed were somewhat more alike in size than were the twins of other breed-types; crossbreds were, on average, 50 % less stable than purebreds in average size () ; although crossbreds grew with somewhat greater stability ().

5. Whatever their mean size, all pairs of identical twins of the same breed appeared to grow postnatally with more or less equal stability (). Small, slow growing pairs showed a greater disparity in average size ().

6. Stability of development continually changed with age but not violently. Each body measurement appeared to have its own characteristic age trend. It is false to believe that variation automatically increases with increasing age. As they grew older, identical twins tended to become less alike in their later maturing body measurements whereas their early maturing body measurements tended to decline in variability. There was an overall trend with degree of maturity; variability steadily increased to a maximum and subsequently declined.

7. It is suggested that environmentally induced instability of development may remain at a minimum level so long as growth curves are not seriously distorted from their exponential path to maturity.
Inbreeding depression in grazing Blackface sheep
Authors: Doney J. M.
Published: September 2010

Four Scottish Blackface rams were mated with a group of their own daughters and a similar number of non-related ewes. The matings were made in three successive years. All ewes were maintained under normal hill conditions. Female progeny from the matings entered the ewe flock unculled. Records of birth type, birth weight, fleece and live-weights throughout life were obtained.

Inbred lambs had lower mean values for all measured characters than did their non-inbred half-sibs and there was a greater number of apparently barren ewes amongst the flock ewes which were expected to produce inbred lambs. The inbred progeny, also maintained in the normal hill flock, showed a higher incidence of barrenness and lower lamb survival rates at all ages than did their non-inbred contemporaries in the same environment. In the final year of the observations, when the standard of nutrition during late pregnancy was raised, the neo-natal mortality rate in both groups was reduced.
The representation of yield of dressed carcass
Authors: Seebeck R. M. , Tulloh N. M.
Published: September 2010

1. Because dressing percentage increases as body weight increases, an adjustment for body weight is necessary when the dressing percentages of animals of different body weights are being compared. Instead of comparing animals on this basis, it is suggested that the power function y = axb, relating carcass weight and body weight, when computed in the logarithmic form, provides a suitable method for making adjustments of this kind.

2. Using this function, differences in yield of carcass have been shown, between breeds and between seasons, in a study involving Hereford, Aberdeen Angus and Beef Shorthorn cattle.

3. A similar function has been used to describe the relationship between fat content of carcass and carcass weight and body weight, using data from the same breed study.
Coat structure and seasonal shedding in goats
Authors: Ryder M. L.
Published: September 2010

Monthly coat and skin samples were taken from three goats for one year in Australia, and from six others for two years in Scotland. The coat appeared to have a simple cycle of active growth in summer followed by inactivity in winter.

The kemp fibres of the outer coat formed brush ends at about the time of the autumn equinox and remained dormant until late spring. Follicles developed first in the foetus formed a brush first. No moult was obvious because new kemps grew before all the old ones had shed, the only manifestation of shedding being a shortening of the coat. The old wool tended to be lost before growth of the new, so that wool was completely lacking in the coat during summer.

Observations on skin sections showed that the majority of both kemp (primary) and under-wool (secondary) follicles become active immediately after the longest day, although there was a tendency for re-growth of wool fibres to be delayed, particularly in females.

Whereas the proportion of kemps with brush ends during winter reached 100%, the proportion among wool fibres was as low as 50%. A complete explanation for this is not yet evident. The bad winter of 1963 apparently caused a greater proportion of secondaries to form brush-ends earlier and to remain inactive longer.

Details are given of some of the histological features of brush formation.
A note on the performance of growing-finishing swine in an open front pole barn
Authors: Curtis R. J.
Published: September 2010

Open front pole barns have proved to be very economical for the housing of feeder cattle, dry stock and, in certain areas, milking cows in Canada. In California, Heitman and Hughes (1949), Heitman, Kelly and Bond (1958) and Heitman, Kelly and Hughes (1949) investigated the effect of ambient temperatures (40 to 110° F.) and humidity on rate of gain in swine. Optimum temperatures for rate of gain were 73·5° F. and 61° F., for pigs of 100 lb. and 300 lb. live-weight, respectively. Hazen, Currie and Giese (1950), at Iowa State College, showed that growing swine weighing under 100 lb. are less severely affected by cold weather (34 to 40° F.), when protected from wind and wet, than heavier animals are by high temperatures.
A note on copper retention by pigs fed on various protein sources
Authors: O'Donovan P. B. , Spillane T. A. , O'Grady J. F.
Published: September 2010

Since, under Irish conditions, the source of protein used in pig rations often varies from one area to another, an experiment was conducted to determine the accumulation of copper in the tissues of pigs given the commonly-used

protein sources in diets containing 250 ppm of supplemental copper. The protein sources compared were (a) white-fish meal (370 ppm Cu), (b) soya bean meal (17 ppm. Cu), (c) roller-dried skim milk (2 ppm Cu), and (d) a mixture of soya bean meal and meat and bone meal (5 ppm Cu) (Table 1). The minerals, vitamins and copper sulphate were premixed with about 5 kg. of barley and distributed over the total feed before mixing. The copper sulphate was sieved to remove coarse particles. Analyses of complete feed mixtures are shown in Table 1. As far as possible, the rations were balanced for crude protein, calcium and phosphorus.
Effects of divergent selection for body weight on fibre number and diameter in two mouse muscles
Authors: Hanrahan J. P. , Hooper A. C. , McCarthy J. C.
Published: September 2010

The effects of selection for increased or decreased body weight in mice, at 5 or 10 weeks of age, on the fibre number, fibre diameter and weight of the m. sternomastoideus and m. anterior tibialis muscles were studied. Unselected control mice were also included. Significant effects were detected in the case of each of the traits. However, the magnitude of any particular correlated response to selection varied between muscles and between selection ages in an unsystematic fashion. Most of the changes in muscle weight resulting from selection were attributable to positively correlated changes in fibre number but they were also accompanied by changes in fibre diameter in some cases.

The correlated responses described indicate the difficulty of predicting how selection for body weight changes will influence cellular structure of any given muscle.

Phenotypic correlations between muscle fibre number and diameter were essentially zero. The phenotypic correlations between muscle weight and fibre number and fibre diameter were positive.

Sex had no effect on fibre number but had an effect on fibre diameter which depended on the particular muscle and the age of the animal.
A note on the effect of interbreeding among backcrosses of sheep breeds
Authors: Aboul-Naga A. , Galal E. S. E.
Published: September 2010

The records of 873 lambs from Ossimi and Barki backcrosses to Merino, and the first and second generations of their interbreeding were analysed. The traits included were: birth, weaning and yearling weights, first fleece weight and lamb mortality.

The interbred groups had about 10–15% lower body and fleece weights than their backcross parents, and almost double the lamb mortality. Differences between the interbred groups and the back-cross parents were predicted from the performance of purebreds, first crosses and backcrosses. There was good agreement between prediction and observation for birth and fleece weights, fair agreement for weaning and yearling weights, but lamb mortality increased more than expected.

Maternal heterosis seems to be more important than individual heterosis for body weight, and the reverse for fleece weight. Both components are large for lamb viability.
A note on the progressive carcass-weight changes of fattening store lambs
Authors: Rutter W.
Published: September 2010

Two experiments involving the sequential slaughter of intensively fattened store lambs were each carried out over a period of 12 weeks. In the first experiment the lambs were offered a concentrate diet ad libitum. In the second experiment they were offered swede turnips ad libitum with a limited amount of concentrates.

In each experiment, similar groups of lambs were slaughtered at equal intervals in order to measure progressive changes in live weight, carcass weight and dry-matter intake. Carcass-weight gain as a proportion of live-weight gain was found to be 74% in the first experiment and 86% in the second experiment.
Genetic relationships of reproduction with growth and with carcass traits in British pigs
Authors: Morris C. A.
Published: September 2010

Data werfe analysed of litters from Large White and Landrace herds which were tested at central stations in Great Britain for growth and carcass traits. Information on reproductive performance of young females was combined with data on their relatives at central stations in order to calculate genetic relationships of reproduction with growth and with carcass traits. Progeny testing of boars for both sets of traits was the most efficient of the methods considered for this analysis.

In general, the estimated genetic correlations of reproductive performance with growth and with carcass traits were alike in sign for the two breeds, and the signs of the matrix of values were internally consistent. For example, combining data for litter sizes in the Large White breed, genetic correlations were −0·15 (food conversion ratio), 0·06 (daily gain), −0·18 (average backfat depth), −0·63 (killing-out percentage) and −0·41 (hind quarter percentage). When the growth and carcass traits were combined as total points score in a selection index, the genetic correlation between this score and reproductive performance was very small, with a range from −0·04 to 0·02. Calculations showed that inclusion of reproductive performance in the index would increase the rate of genetic improvement by only 0·55%.
Protein levels in diets for European pigs in the tropics. 1. The effect of methionine supplementation on the protein requirement of growing pigs
Authors: Fetuga B. L. , Babatunde G. M. , Oyenuga V. A.
Published: September 2010

One hundred and twenty-eight Landrace and Large White pigs were allocated on the basis of sex, litter origin and initial weight to one of 16 treatments, made up of four basal 16, 18, 20 and 22% protein diets, each supplemented with either 0·00, 0·10, 0·15 or 0·20% synthetic DL-methionine, at a common digestible energy level of 3740 kcal/kg. Pigs were reared between 8 and 50 kg live weight. Growth rate of pigs and efficiency of feed conversion were significantly improved as the protein levels were increased up to the 20% protein level, optimal performance being on the 20% protein diet, with added 0·15% methionine, giving a total methionine+cystine level of 0·65% and a lysine level of 1·07%. Addition of synthetic methionine to the diets resulted in significant improvement in the rate and efficiency of gain only at the 16 and 18% protein levels.

Carcass leanness and fatness increased and decreased respectively over the whole range of protein levels. Graded addition of DL-methionine within each protein level did not influence carcass characteristics.

Nitrogen retention showed optimal utilization of dietary nitrogen to be at the 18% protein level, with a total dietary methionine + cystine level of 0·61%, which was at variance with the levels indicated by both growth and feed efficiency.
A note on the performance at pasture of British Friesian steers previously offered dried grass or concentrates
Authors: Marsh R. , Murdoch J. C.
Published: September 2010

Three experiments are described in which castrated male (steer) calves previously reared to 6 to 7 months of age on dried grass ad libitum gained weight faster, following turnout to pasture, than calves previously reared on a cereal/protein concentrate ad libitum. Rate of gain at pasture was found to be more an effect of previous rate of gain than of diet per se. There were indications that calves whose growth rate had been previously restricted ate more herbage per unit live weight than calves whose growthrate had not been restricted.
Effect of concentrate: roughage ratio on the production of beef from Israeli-Friesian bulls slaughtered at different live weights
Authors: Levy D. , Holzer Z. , Folman Y.
Published: September 2010

The effects of roughage level (15 and 35% of the ration) and of slaughter weight (400,450 and 500 kg) were studied in an experiment of 2 x 3 factorial design. Daily live-weight gains and carcass gains were significantly higher on the lower roughage levels, but there was no difference in degree of fatness of the carcass. Dry-matter intake expressed as a percentage of body weight was 2·91 on 35% roughage compared with 2·53 and 15% roughage, i.e. 15% higher on the highroughage diet. This compensated the animals on the high-roughage diet for the lower energy content of their feed. Rate of gain increased with an increase in slaughter weight. The percentage of fat trim and of saleable meat increased, while that of bone decreased significantly with an increase in slaughter weight. The animals on the lowroughage diet were approximately 11% more efficient than the others in converting metabolizable energy into live weight.
Calf mortality in pure and crossbred Zebu cattle and Murrah buffaloes reared artificially from birth
Authors: Sharma K. N. S. , Jain D. K. , Noble D.
Published: September 2010

Mortality to one year of age was studied in artificially-reared calves of Tharparkar, Sahiwal and Red Sindhi breeds together with Murrah buffaloes and Brown Swiss x Sahiwal and Brown Swiss x Red Sindhi. Data covered 6267 animals over the period 1952–71. There were significant breed differences with the Brown Swiss crosses and buffaloes suffering higher losses than the Zebu breeds. Age effects (0 to 1, 1 to 3, 3 to 6 and 6 to 12 months) showed that losses were greatest in the first month of life and declined thereafter. There were significant year effects but seasons (summer, monsoon and winter) showed no significant effects although a tendency to higher losses in winter did exist. Sex effects showed no differences. Pneumonia was the major cause of loss to 6 months accounting for 30 to 40% of deaths with scours and enteritis being the second most serious factor (15 to 35% of losses).
A comparison of farm and station performance testing of boars
Authors: McPhee C. P.
Published: September 2010

By fitting a range of numerical values to a model, genetic responses from performance testing male pigs (boars) were examined in a population in which pig farms either conduct their own tests or send boars to a central station for testing. Where selection intensities are the same for station and farm tests the former almost always has an advantage over the latter. Factors which lead to this advantage are genetic differences between farms, genetic sampling within farms and limitations on the accuracy of performance measurement in farm tests. In a large station test response in a trait of 50% heritability is expected to be 15% greater than in tests comprising boars from 10 effective parents on farms whose average genotype contributes 5% of the total genetic variation and whose environmental variation is 25% greater than in the station. In populations with limited station testing space available, farm tests should be able to compensate for their lower efficiency by increasing selection intensities.
A Note on the effect of herbicides on the metabolism and performance of lambs
Authors: Abou Akkada A. R. , Hassan M. A. , Naga M.
Published: September 2010

The inclusion of 60 p.p.m. of 2,4-dichlorophenoxy acetic acid (2,4-D) or of M15† in the diet of lambs had no effect on the concentrations of volatile fatty acids and ammonia in rumen liquor, on the contents of haemoglobin, protein and non-protein nitrogen in blood or on the composition of the blood serum proteins. Over weeks 1 to 6 of experiment, there was a significant increase in live-weight gain in lambs receiving a diet containing M1S but the effect had disappeared at the end of 12 weeks. Inclusion of 2,4-D in the diet had no effect on live-weight gain.
Studies in sow reproduction 5. The effect of lactation length of the sow on the subsequent embryonic development
Authors: Varley M. A. , Cole D. J. A.
Published: September 2010

Forty-five female pigs (sows) were allocated at random to one of three lactation lengths: 7 days, 21 days, 42 days. All sows were remated at the first post-weaning oestrus and were slaughtered at 20 days post coitum. The reproductive tracts were removed, dissected and examined. Ovulation rates as determined by luteal count were similar for all three groups, but the number of viable embryos decreased significantly (P < 0·05) from 13·0 for the 42-day lactation group to 9·2 for the 7-day lactation group. This difference was reflected in a significant (P < 0·01) reduction in the percentage embryo survival rate as lactation length was reduced. Uterine lengths for the 7-day lactation group were significantly (P < 0·05) shorter than the other two groups. Six sows in each treatment group were blood sampled: at weaning, at remating, at 2 days post-mating, at 10 days post-mating and at 20 days post-mating. The plasma samples obtained were assayed for progesterone. No differences were observed between treatment groups for plasma progesterone concentration at any of the sampling times. It is concluded that the reduction of the litter size at the next farrowing following a short lactation length is largely a result of increased embryo death in the first 20 days of gestation.
Dried sugar-beet pulp as a roughage substitute for pregnant ewes
Authors: Dickson I. A. , Laird R.
Published: September 2010

In 1968-69 for a mean period of 101 days before lambing, 72 cross-bred ewes, and in 1969-70 for a mean period of 88 days, 107 ewes were given roughage daily in the form of (a) 0·91 kg field-cured hay (b) 0·45 kg of hay plus 0·23 kg dried sugar-beet pulp nuts, or (c) 0·45 kg of pulp nuts. Each diet was supplemented by a concentrate allowance. From the 6th week before lambing was due to start, this allowance was progressively and uniformly increased.

There was no evidence that the dried sugar-beet pulp had adversely affected performance in terms of ewe body-weight change, lamb numbers, litter weight at birth or 4 weeks of age, fleece weight or general health. It is therefore concluded that dried sugar-beet pulp can be used safely as a replacement for hay in supplying up to 67% of the energy needed for maintenance by ewes.
A note on the association between transferrin types and some productive traits in Iranian sheep
Authors: Pasdar M. , Makarechian M. , Farid A.
Published: September 2010

An investigation was made of the association of transferrin types with birth weight, weaning weight and average daily gain from birth to weaning in three breeds of Iranian sheep. Transferrin type was not a significant source of variation in weight.
Tissue growth in the pig
Authors: Cole D. J. A. , White M. R. , Hardy B. , Carr J. R.
Published: September 2010

Growth coefficients were determined for muscle, bone and fat in the side and in the ham, for six muscles of the ham, and for the femur, using data obtained from the dissection of 66 carcasses of female pigs weighing from 25 to 65 kg live weight.

Irrespective of the independent variable taken for regression, the coefficients showed bone in the side to be earlier developing than muscle, which in turn was earlier than fat. There is good agreement between these coefficients and corresponding values reported for cattle, sheep and pigs.

There was little evidence that the ham as a whole or its muscle, bone and fat components grew disproportionately to the corresponding components of the whole side.

The growth coefficients of the six muscles of the ham agreed closely with those reported for cattle, sheep and pigs with the exception of that for the m. adductor, which was lower.

The combined weights of the m. biceps femoris and m. adductor were related almost as closely to the weight of muscle in the side as was the weight of total muscle in the ham. Of the six muscles taken individually the weight of the m. biceps femoris was most closely related to muscle in the side.
A note on the utilization by calves of maize and potato diets in liquid suspension or in dry form
Authors: Hinks C. E. , Whittemore C. T.
Published: September 2010

Forty British Friesian male calves were pair-fed creep feeds containing 67% of either cooked potato or cooked maize in the form of a dry coarse meal or finely ground in liquid suspension.

Although dry maize diets were more acceptable than dry potato diets, daily gains were unaffected by either diet composition or drymatter content.

Calves on liquid-fed diets produced faeces of significantly lower dry-matter content.
A note on the relationship between ultrasonic fat measurement and performance in beef cattle
Authors: Moran J. B. , Holmes W.
Published: September 2010

The development of subcutaneous fat as measured by ultrasonics was determined in 28 Angus, 46 Hereford and 42 Charolais bulls, performance-tested on a barley/grass diet. The ultrasonic fat measurements were then examined for possible relationships with feed intake, growth rate and feed conversion efficiency. There were apparent breed differences in the rate of increase in subcutaneous fat thickness with changing live weight but ultrasonic measurements bore little relationship to performance parameters within any of the three breeds tested.
A note on live-weight adjustment for pregnancy in cows
Authors: Silvey M. W. , Haydock K. P.
Published: September 2010

Since comparison of live-weight change of breeding cows is complicated by pregnancy and reproductive synchrony, possible analytical methods for overcoming these problems were reviewed. It was concluded that correction of cow live-weight by subtracting the weight of the gravid uterus and products of conception was biologically and practically meaningful. Two exponential models using polynomial coefficients were derived from published data to predict the fresh weights, at any time during gestation, of the foetus (calculated from calf birth weight) and the gravid uterus and foetal membranes and fluids.
A note on the comparative performance of pigs sired by Piétrain × Large White and Large White boars
Authors: Smith W. C. , Toft C. R. , Handscombe N.
Published: September 2010

A Piétrain × Large White boar and a Large White boar were placed on each of 12 farms where the breeding females were crossbred white sows. Cooperators were requested to obtain 10 litters by each sire and record their performance to slaughter at 60 kg live weight. Breed of sire did not affect litter size or piglet body weight at birth or at weaning, age of progeny at slaughter, carcass mid-line fat depths or colour and condition of the ‘eye muscle’. Piétrain crosses had higher carcass yields (1·8%) and larger eye muscles in cross-section (13·2%) than Large White crosses. They also had less depth of fat above the eye muscle (14 %) but this did not confer any advantage in commercial evaluations.
Short-term fluctuations in the live weight of identical twin cattle
Authors: Taylor C. S. , Griffiths R. G. , Donald H. P.
Published: September 2010

Two pairs of uniformly treated identical twins were weighed four times daily for 16 days. In addition, daily growth rate was analysed for 10 pairs of identical twins kept on high and low planes of nutrition over a 16-week period.

Identical twins fluctuated in body weight from hour to hour and day to day in a significantly more similar manner than did unrelated animals. The greater similarity found when all animals were uniformly treated still persisted when identical twins were placed on different planes of nutrition.
Bull beef production from suckler herds of traditional breed type
Authors: Robertson I. S. , Lowman B. G.
Published: September 2010

The feasibility of producing bull beef in suckler herds of traditional breed type was investigated in two parts. A controlled feeding experiment (Part 1) was carried out with weaned bull and steer calves slaughtered at 398, 432 and 466 kg live weight. Bulls and steers were compared on a standard level of feeding and in addition a group of bulls was given a ration providing a 20% higher daily intake of metabolizable energy. This latter group grew significantly faster than the control bulls and steers, and consumed similar total amounts of metabolizable energy when slaughtered at the same final weight. Carcasses from both groups of bulls were significantly leaner than those of steers. With regard to weight of lean produced per day of age the ranking was bulls on the high energy diet > other bulls > steers.

In Part 2 the performance and management demands from birth to slaughter of bulls and steers were compared in a number of spring and autumn-calving herds. Bulls gained live weight more rapidly than steers and although they were taken to heavier slaughter weights their carcasses were significantly leaner. Some readjustment of management practices, e.g. separation of male and female calves with their dams was required. No serious behavioural problems were encountered during the suckling or finishing stages.

A consumer acceptance trial showed that, in relation to steaks normally purchased, 61% of local consumers judged bull steaks as average or above in eating quality compared with 91% for steer steaks. It is concluded that although bull beef production is feasible a market outlet is an essential prerequisite.
Studies in sow reproduction 6. The effect of lactation length on pre-implantation losses
Authors: Varley M. A. , Cole D. J. A.
Published: September 2010

Thirty Landrace × (Landrace × Large White) sows were used to investigate the importance of pre-implantation losses in the embryonic mortality of the early-weaned sow. The sows were allocated at random to one of two lactation lengths, namely, 7 or 42 days. Following weaning and remating the sows were slaughtered at 9 days post coitum. Ovulation rates were similar for both groups (15·3 and 15·1 for the 7-day and 42-day weaned groups respectively). Numbers of embryos present at 9 days post coitum were 12·5 for the 42-day group and 11·2 for the 7-day group and the difference was non-significant. Percentage embryo survival was 83·5% for the 42-day group and 74·3% for the 7-day group; the difference was non-significant. It was concluded that the bulk of embryo loss in the early-weaned sow occurred after the pre-implantation stage and was probably at or around implantation.
The performance of sows and litters penned individually or grouped in late lactation
Authors: Petchey A. M. , Dodsworth T. L. , English P. R.
Published: September 2010

Piglets in litters reared in groups from 3 to 7 weeks of age weighed less at weaning (7 weeks) than piglets in which litters were penned individually. Some of the difference between the two management systems was created within the week after grouping. Grouping sows and their litters did not initiate oestrus in lactation. The subsequent litter size of the grouped sows was reduced but between-treatment differences for this trait failed to reach significance at the 5% level.
A time-controlled feeding system for cattle
Authors: Shaw R. A.
Published: September 2010

A system of time-controlled feeding has been developed to give a considerable degree of control over the food intake of animals without eliminating individual variation.

The system is based on the Calan-Broadbent electronic feeding doors and animals are conditioned by certain electrical and sound stimuli to use the doors only during prescribed periods. Clock mechanisms control the time intervals when electric power to the doors is on or off.

Times and durations of feeding can be adjusted so that a predetermined level of intake is obtained, and a heavy demand on labour is avoided.

In the present trial, British Friesian and Jersey cattle on a time-controlled feeding regime were compared with animals given access to food ad libitum. A significant reduction in food intake due to time-controlled feeding was detected in both breeds over a 6-month period.There was no evidence to suggest that the particular time-controlledfeeding regime restricted one breed more than the other.
Substitution rates in steers fed on low quality grass hays supplemented with maize grain
Authors: Torres F. , Boelcke Cristina
Published: September 2010

To estimate the effect of supplementation on hay: grain substitution rates, 18 experimental rations were evaluated in digestibility trials, each using four steers (300 kg live weight) housed in metabolism stalls. Four hays (digestible dry matter = 40 to 62 %) were given to appetite, supplemented with maize grain plus urea at several different levels, up to 2·5% of animal live weight, and substitution rates were estimated as the slope of the linear regression of hay intake on grain intake. General substitution rates were independent of hay quality, and the pooled rate was 830 g (Sb = 0·036) per kg of grain dry matter. Nevertheless, the analysis of the observed partial substitution rates and those in the literature, suggests a possible interaction between the effects of hay digestibility and grain level on substitution rates.
Effect of dietary lysine levels on performance, nitrogen metabolism and plasma amino acid concentrations of lactating sows
Authors: Chen S. Y. , d'Mello J. P. F. , Elsley F. W. H. , Taylor A. G.
Published: September 2010

During lactation 30 sows were given a basal diet containing 0·39% lysine or the same diet supplemented with 0·1, 0·2, 0·3 or 0·4% Llysine. In addition a group of six sows was given a high protein/high lysine control diet containing 17% crude protein and 1·06% lysine. Piglet weight gain, sow milk yield, milk contents of total solids, protein, fat and energy and efficiencies of utilization of energy and protein for milk production increased progressively as dietary lysine levels were raised to 0·59 %. Sows receiving the lysine-supplemented diets had markedly higher efficiencies of conversion of dietary protein into milk protein and lower efficiencies of energy utilization than those given the high protein/high lysine control diet.

Nitrogen retention and biological value of the dietary protein increased quadratically with increasing dietary lysine concentrations, reaching maximum values at 0·59% lysine.

Apparent digestibilities of isoleucine, lysine, methionine, threonine and valine in the basal diet were closely correlated with digestibility of nitrogen. Plasma lysine concentrations remained depressed and relatively constant at low dietary levels of lysine, but increased sharply at 0·59 % dietary lysine coinciding with a marked drop in circulating concentrations of other essential amino acids.
Changes in the body composition of cattle exhibiting compensatory growth and the modifying effects of grazing management
Authors: Baker R. D. , Young N. E. , Laws J. A.
Published: September 2010

Friesian steer calves born in August were reared from 3 to 7 months of age on either a low (OL) or high (OH) plane of nutrition. A further group born in October (YH) was also reared on a high plane. At grazing, the performance of calves of the same age but different weights (OL v. OH) or the same weight but different ages (OL v. YH) were compared at two levels of herbage allowance, either 30 or 60 kg dry matter per kg live weight. During the winter, the H groups received silage and concentrate and the L group was given silage only. The OL group had a higher concentration of fat and a lower concentration of water in the empty body at the end of the winter than did the OH and YH groups respectively.

Compensatory growth was exhibited by the OL group at both herbage allowances. Differences in the live-weight and empty body-weight gains of OL and OH cattle could be explained almost entirely by differences in the energy content of the gains whereas this was only partially so when the OL and YH groups were compared. The results indicate that YH cattle had lower herbage intakes even though they were of similar weight to OL cattle.

It was concluded that silage nitrogen is used less efficiently by cattle than is generally assumed and that the levels of gut fill and energy content of the live-weight gains in this experiment were not consistent with the general values suggested by the Agricultural Research Council (1980).
The effects of level of maize gluten feed in the diet on pig performance and carcass quality
Authors: Edwards Sandra A. , Prescott Nicola J. , MacDougall D. B.
Published: September 2010

Diets containing 0, 100, 200 or 300 g/kg of maize gluten feed were formulated, using standard tables of ingredient values, to have similar levels of digestible energy (12·9 MJ/kg) and lysine (8·9 g/kg). Each diet was scale fed to four pens of eight pigs, entire males and females, from 37 kg until slaughter at about 85 kg.

There were no problems with diet palatability and no significant differences in live-weight gain, food conversion efficiency or killing-out proportion. With increasing maize gluten feed, dietary lysine increased (8·5, 8·6, 8·9, 9·0 g/kg) and backfat thickness decreased (P1 + P3 = 28·6, 27·2, 25·5, 24·9 mm, P < 0·05). Fat samples were taken from the last rib position on each side of all carcasses. With increasing maize gluten inclusion the fat (inner layer) became darker (P < 0·001) and yellower (P < 0·05). Increasing maize gluten feed also increased levels of linoleic acid (170·4, 195·8, 224·8, 247·7 g/kg total fatty acids; P < 0·001) indicating that progressively softer fat would be produced. The results show that inclusion rates of maize gluten feed up to 300 g/kg did not adversely influence pig performance or carcass characteristics but the appearance and keeping quality of the fat might be adversely affected by higher levels.
Variance of body weights and daily weight gains of weaner pigs housed at various stocking densities in confinement
Authors: Kornegay E. T. , Notter D. R. , Bartlett H. S. , Lindemann M. D.
Published: September 2010

Body weight and gain data from eight studies conducted with weaner pigs to determine the relationship between stocking density and performance were used to evaluate the effect of various stocking densities on several factors which measure variation within pens. The initial weight of the pigs ranged from 5·7 to 8·3 kg and final weight ranged from 17·7 to 32·1 kg. There were 244 pens of pigs with floor space ranging from 0·11 to 0·28 m2 per pig. Average daily gain and body weight were depressed as stocking density increased. Natural logarithms of variance, coefficients of variation and ranges of average daily gains and body weights were not increased by stocking density. Body weights and daily gains appeared equally effective in measuring variance of weaner pigs housed at various densities. These results indicate that increasing stocking density within the range of densities tested does not cause a greater variation in body-weight gains.
Scope for selecting many breeding stocks of possible economic value in the future
Authors: Smith C.
Published: September 2010

Current animal improvement deals largely with selection of stocks for current economic objectives. However, there is uncertainty about how well these objectives will hold in the future, since husbandry and marketing needs and conditions may change unpredictably over time. The scope for developing alternative stocks, selected for different chosen sets of objectives, is considered, so that by substitution or crossing it may be possible to reduce the uncertainty and better meet future needs and conditions. The reduction in uncertainty is modelled by including risk or uncertainty in the discount rate in assessing benefits over time from one cycle of selection. From the national viewpoint, the costs of developing alternative selection stocks are small relative to the possible returns. Thus, if the uncertainties were reduced by having them, a large number of such alternative stocks would be justified. The expected benefits to the community from animal breeding would also be increased thereby.
A note on the critical temperature of the fasted and fed early-weaned pig
Authors: Jordan J. W. , McAllister A. , Weatherup S. T. C.
Published: September 2010

The heat production of fasted and fed littermate pairs of pigs weaned at 10, 17 and 24 days of age was determined between 16 to 34°C. Up to and including 34°C the post-weaning heat production of fasted pigs at 10 and 17 days of age decreased with rising temperature. Rectal temperatures of all 24-day-old fasted pigs were higher at 34°C than at 31°C. For fed pigs weaned at 10 days of age the heat production continued to decrease up to and including 34°C. The decrease between 28°C and 31°C and between 31°C and 34°C was comparatively small and rectal temperatures were slightly elevated at 34°C. The results indicated that for fed pigs weaned at 17 and 24 days the thermoneutral zone was in the region of 31°C and the lower critical temperatures were about 28°C.
Influence of liver fat on post-partum hormone profiles in dairy cows
Authors: Watson Elaine D. , Williams Linda A.
Published: September 2010

Cows (no. = 11) were classified from liver biopsies taken 7 to 10 days after calving as having mild (FL1, no. = 6), or moderate (FL2, no. = 5) fatty infiltration of the liver. Blood samples were collected from the jugular vein: (1) three times weekly and assayed for progesterone and oestradiol; (2) at 10-min intervals for 8-h periods on three occasions during the early post-partum period and assayed for LH; (3) every 2 h, with ovarian palpation performed every 4 h around the second or third post-partum ovulation, and assayed for LH and oestradiol.

Mean weekly concentrations of oestradiol were not significantly different between FL1 and FL2 cows. FL2 cows tended to have short (< 17 days) first cycles (3/4 FL2 v. 0/5 FL1) with significantly lower concentrations of plasma progesterone (P < 0·05). Mean basal concentrations of LH in the samples collected at 10-min intervals tended to be lower in FL2 than in FL1 cows; however, the difference was significant only in the 2nd week of sampling (P = 0·05). Mean basal concentrations of LH were significantly higher in weeks 3 and 4 than in week 2 in FL1 but not in FL2 cows (P < 0·05). The frequency and amplitude of LH pulses were not affected by week of sampling or by fat content of the liver. The total area under the profile of LH during the pre-ovulatory surge was lower in FL2 than in FL1 cows (P < 0·05) but peak plasma concentrations of pre-ovulatory oestradiol and timing of ovulation after the LH surge were similar.
Cereal straw in diets for beef cattle: effects of pattern of growth and diet formulation on growth rate and food conversion efficiency
Authors: Macdearmid A. , Williams P. E. V. , Brewer A. C.
Published: September 2010

Five groups of Hereford × Friesian steers (initial weight 340 kg) were given either a diet of rolled barley and ammonia-treated barley straw (AS) in the ratio 60: 40 ad libitum (ASB) to support continuous growth, or were offered over a 143-day period diets of either (i) AS alone (diet AS) (ii) untreated straw (US) plus cassava (diet USC) (iii) US plus grass silage (diet USS) or US plus fish meal (0·27 kg fish meal per day) (diet USF). Both the AS and US were offered ad libitum and allowances of cassava and silage adjusted to allow the USC and USS steers to match the growth of AS steers. Steers i n the restricted groups (AS, USC, USS and USF) were then given freshly cut grass ad libitum until they reached slaughter weight; some steers required additional hay and barley to reach slaughter weight. Steers in group ASB consumed 7·4 kg dry matter (DM), gained 1·16 kg live weight per day taking 112 days to achieve the 455 kg slaughter weight. AS, USC and USS animals maintained body weight over the restricted period, whereas the USF group tended to lose weight and daily DM intakes were 4·63 kg AS (AS steers); 3·81 kg US plus 0·95 kg cassava (USC steers); 0·86 kg US plus 3·31 kg silage (USS steers); 3·5 kg US plus 0·27 kg fish meal (USF steers). When grass or grass followed by barley plus hay was given the live-weight gains of the previously restricted cattle did not differ (mean 1·0 (s.e. 0·10) kg/day). AS provided proportionately 0·30 of the metabolizable energy used to produce growth rates in excess of 10 kg/day or if given as the sole food maintained cattle without supplementation.
Effect of level of food intake at mating on the reproductive performance of ewes passively immunized against testosterone
Authors: Rhind S. M. , Morris B. A. , Clayton Jill , Gittus G.
Published: September 2010

In a 2 × 2 × 2 experiment, 296 Scottish Blackface ewes were fed to achieve one of two levels of body condition (high: condition scores ^2·75; low: condition scores ^2·50) by 2 weeks before joining with rams. Half of the ewes of each condition score were fed dried grass pellets ad libitum and 300 g hay per head daily, between 2 weeks before and 8 days after joining, while the remaining ewes were offered a live-weight maintenance ration comprising 750 g pellets and 400 g hay per head daily. From 8 days after joining the intake of all ewes was gradually changed, over a 2-week period, to 1250 g pellets and 400 g hay per head daily. Two days before joining, half of the ewes of each condition/intake group were passively immunized against testosterone. A total of 99 ewes were slaughtered 18 days after joining and their ovulation rate at the first mating determined. Ovulation rates were significantly affected by immunization (immunized: 2·31, control: 1·86, pooled s.e. = 0·055; P < 0·01) and food intake (ad libitum: 2·24, maintenance: I 92, pooled s.e. = 0·055; P < 0·05) but not by body condition at mating (high: 2·15, low: 2·02, pooled s.e. = 0·059; P > 0·05). Lambing rates were dependent on treatment (immunized: 1·82 control: 1·62, pooled s.e. = 0·044; P < 0·01), food intake (ad libitum: 1·85, maintenance: 1·59, pooled s.e. = 0·043; P < 0·01) and body condition (high: 1·82, low: 1·62, pooled s.e. = 0·044; P < 001). In ewes in a high body condition at mating, the effects of intake and immunization were additive but in ewes in low condition, immunization induced little improvement in performance in ewes fed ad libitum. Circulating antibody titres were lower in ewes fed ad libitum than in ewes offered a maintenance ration (1: 416 v. 1: 534, pooled s.e. = 14; P < 0·001), but ovulation rates and litter sizes were not related to titres.
Evaluation of large White and Duroc boars as terminal sires under two different feeding regimes
Authors: Simpson S. P. , Webb A. J. , Dick S.
Published: September 2010

Large White and Duroc semen was used to form a three-breed cross from Large White x Norwegian Landrace dams. A pair of sibs from each litter was fed ad libitum and a further pair on a time-based scale at the Meat and Livestock Commission testing station at Stirling, Scotland. A total of 241 litters was tested. At the end of testing the pigs were slaughtered and standard carcass measurements were made. One side of the carcass of each of a sample of 60 pigs was fully dissected. The Duroc progeny grew faster and had better food conversion efficiency than the Large White progeny when fed ad libitum but there was no difference between the breeds when feeding was restricted. The Large White progeny produced a better trimming yield and were slightly longer. There was no significant difference in fat depths. The proportions of lean, fat and bone tissues did not differ greatly between the breeds although the Large White progeny had slightly more lean tissue and the Duroc progeny were more heavily boned and had more intermuscular fat. The Duroc terminal sires gave an economic advantage of £1·70 per pig when fed ad libitum but a loss of £0·35 when fed to a restricted scale. This was primarily due to the superior growth rate and food conversion efficiency of the Duroc progeny when fed ad libitum.
A genetic analysis of litter traits in Bauscat and Giza White rabbits
Authors: Khalil M. H. , Owen J. B. , Afifi E. A.
Published: September 2010

An analysis of doe productivity traits was carried out on 884 litter records including 52 sires and 210 daughters (paternal half sisters) of Bauscat (B) and Giza White (G) rabbits. Traits examined included litter size and weight at birth and at weaning, pre-weaning mortality and mean weight of young at weaning. Year-of-kindling affected most litter traits but no pattern of parity effects on litter size and pre-weaning mortality was observed. Litter weight and mean weight of young at weaning generally increased linearly as parity advanced. Litter size and weight and mean weight of young tended to increase as month of kindling advanced from October to March, and to decrease again during April and May. Pre-weaning mortality decreased as month of kindling advanced up to March and increased thereafter during April and May. The sire of the doe affected all litter traits studied, with the exception of litter size at birth and pre-weaning mortality in the B breed. Estimates of heritability for most of the litter traits were moderate or high. Genetic and phenotypic correlations among litter size traits and between litter size and litter weight traits were positive and relatively moderate or large. Litter weight traits were positively correlated both genetically and phenotypically. The genetic and phenotypic correlations between litter size traits and mean weight of young at weaning were negative and relatively moderate or large.
A note on the effect of marketing route on weight loss in lambs sent for slaughter
Authors: Evans D. G. , Sains A. G. , Corlett I. K. , Kilkenny J. B.
Published: September 2010

It is widely believed that marketing route—time and distance between farm and abattoir—influences live weight and carcass weight loss in lambs and thus killing out. Killing out s i defined as the ratio of carcass weight to live weight but the value depends upon the live weight and carcass weight used. Differences may exist between the farm live weight immediately before loading, live weight in the market, live weight on arrival at the abattoir and live weight immediately before slaughter. Killing out is influenced by the weight of gut contents, whether the carcass is weighed hot or cold, type of feeding system, maturity (age) of the lamb, breed, conformation and fatness. It may also be influenced by environmental factors such as wetness and fleece contamination. Buyers' estimates of killing out are important when they bid for lambs in auction markets and carcass weight is important in determining price paid to dead-weight sellers.