bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of genetic change in farm livestock using field records
Authors: Smith Charles 
Published: September 2010

This paper describes the estimation of genetic changes in farm livestock using field data. The method proposed depends on a difference in rate of change in performance of the population and of the successive progenies of individual sires. The change in the population with time is taken as t+g, where t represents environmental change and g represents genetic change, while the within-sire change is taken as t+½g. Their difference measures half the genetic change.This principle can be applied, with certain precautions, tofielddata where there is some spread of sires over time. The method has two advantages over other methods in that past as well as current changes can be measured and no additional facilities are required. However, selection among sires may bias the estimates of genetic change. Approximate sampling errors of the estimates of change can be obtained and hence the rate of genetic change which a certain body of data will demonstrate to be significant can be estimated.The method was applied to a set of pig records collected over nine years by a private pig breeder. There was considerable change with time in all six traits examined and in at least three of them there appeared to have been a substantial genetic change accounting for the whole of the observed change.
An experiment with a constant environment for the domestic fowl
Authors: Greenwood Alan W. 
Published: September 2010

A pilot experiment is described to observe the effect of a constant environment (temperature 65° F., relative humidity, 60%, artificial light for 12 hours daily alternating with 12 hours darkness, and constant diet) on the subsequent reproductive performance of fowls maintained under these conditions from hatching to the end of the 3rd annual cycle of egg laying.The elimination of normal seasonal moulting of the plumage both at the beginning and at the end of the pullet laying year gave an advantage of 57 eggs for experimental birds over a group of sisters maintained under a more normal system of intensive husbandry.This advantage in eggs laid was much reduced in succeeding years owing to a persistent and continuing decrease in rate of lay of hens in the constant environment.All eggs were incubated and, although no differences in fertility, dead germs and hatchability were observed over the first full year of production in the birds in contrasting environments, the deleterious effects of a constant environment became increasingly apparent with age.It is suggested that control of the environment induces a premature senility in the domestic fowl.
Insemination before and after the onset of heat in sows
Authors: Hancock J. L. , Hovell G. J. R. 
Published: September 2010

Counts were made before and after fixation of the numbers of fertilised and unfertilised ova recovered from 3 mated sows, 7 unmated sows and from 34 sows inseminated at varying times before and after the onset of heat.The percentages of fertilised ova for sows inseminated the day before heat (day — 1) on the first day of heat (day 0) the second day of heat (day 1) and the third day of heat (day 2) are respectively for unfixed and fixed ova: 7·1 and 9·8, day – 1 ; 55·9 and 68·8, day 0; 63·4 and 98·2, day 1; 20·1 and 15·2, day 2. No fertilised ova were recorded from unmated sows; the percentages for mated sows were 94·3 and 95·5.It is concluded that failure of fertilisation is likely to be the greatest source of loss of fertility in inseminations made before heat and late in heat.Most ova from sows inseminated on day — 1 and from sows inseminated in day 2 had no spermatozoa on the zona pellucida. A few ova from sows inseminated on day 2 had very large numbers of spermatozoa present.It is suggested that failure of the spermatozoa to reach the site of fertilisation rather than their loss of fertilising capacity is likely to be the cause of the low fertility of early inseminations.
The measurement of the flow of food to the duodenum of sheep
Authors: Harris L. E. , Phillipson A. T. 
Published: September 2010

1. A comparison of the performance of Scottish Blackface ewe hoggets with and without an exteriorised flow to the duodenum was carried out while the animals were fed on hay with a low nitrogen content and added salt. No evidence was found from the food and water consumed, from the weight changes or from a comparison of the organic matter, nitrogen and ash contents of the food and the faeces that the operation caused any permanent disturbance to digestion.2. Regular measurements of the flow of abomasal contents to the duodenum established a pattern of flow that was influenced by feeding. A relationship between the quantities passed per hour from the abomasum and the time devoted to rumination was found, but the relationship appeared to be dissociated in time so that increased rumination preceded the increased passage of contents.3. The mean quantity of abomasal contents passed from four animals was 398 ml./hour. According to the quantities of chromium sesquioxide administered by mouth, passed from the abomasum, and excreted in the faeces this value represents not more than 90% and not less than 86% of the flow that can normally be expected.4. The quantities of organic matter that disappear in the stomach were calculated and represent about half or more of the total disappearance in the alimentary tract.5. Substantially more nitrogen left the abomasum than was eaten in the food daily. Of the nitrogen passing to the duodenum the greater part disappeared in the intestines.6. About twice as much ash left the stomach as was present in the food and about two-thirds of the ash entering the duodenum disappeared in the intestines.
The maternal effects on size at birth and weaning in Landrace-Native pig crosses
Authors: Joubert D. M. 
Published: September 2010

Reciprocal matings between large, improved Swedish Landrace and small, primitive South African Native pigs produced strong evidence of a maternal effect at birth. However, compared with purebred Landrace piglets, the crossbred offspring out of large dams weighed less; conversely, compared with purebred Native piglets, the crossbred offspring out of small dams were heavier at birth. Differences between the various mean weights were all statistically significant.At weaning (eight weeks of age), the weights of crossbred pigs out of large Landrace sows equalled those of purebred Landrace pigs. Crossbred pigs out of Native-pig sows occupied an intermediate position between the above-mentioned and purebred Native pigs. The differences between the latter group means remained significant statistically.
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 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-usedprotein 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

SUMMARYThe 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

SUMMARYThe 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

SUMMARYTwo 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

SUMMARYData 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

SUMMARYOne 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

SUMMARYThree 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

SummaryThe 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

SummaryMortality 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

SummaryBy 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

SummaryThe 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.