bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships between size, live-weight change and milk production characters in early lactation in dairy cattle
Authors: Wood P. D. P. , King J. O. L. , Youdan P. G.
Published: September 2010

Live weight, milk yield, fat, protein and lactose percentage of 236 cows and heifers of four breeds of dairy cattle were recorded at 2-week intervals, starting within a week after calving, during the winter and spring of 1972/73. Lactation curves of the form X(n) = Xnb ecn were fitted to each animal's records, where X, b, c are constants, e the base of natural logarithms and X(n) the value of the character at the nth 2-week interval. Correlations between the curves, and between deviations from the curves, showed that the production of milk, fat, protein and lactose was negatively correlated with live-weight change in the long term, but that deviations from the curves were not correlated. There were significant positive correlations between milk yield and size, and between potential compositional quality and size (the values of × in the model). Of the four breeds studied, Friesian, Ayrshire, Guernsey and Jersey, adult Friesian cows required less dietary energy per kg of total solids produced than any other group, according to the principles of the metabolizable energy system of calculating energy requirements. During the period of negative energy balance, an average 10% to 15% of energy output in the form of milk was derived from the mobilization of body reserves.
The significance of breed in the prediction of lamb carcass composition from fat thickness measurements
Authors: Wood J. D. , MacFie H. J. H.
Published: September 2010

Fat thickness and measurements of the m. longissimus (‘eye’ muscle) were taken at the last rib in 350 lambs' carcasses which were fully dissected. The lambs were from two ewe breeds, Clun and Colbred, and two ram breeds, Suffolk and Hampshire, and the carcass weight range was 15 to 21kg. Castrated males and females, and singles and twins, were evenly represented.

Rib fat thickness (J) was a slightly more precise predictor of the weights of lean, subcutaneous fat and subcutaneous plus intermuscular fat, when used in a multiple regression equation along with carcass weight, than fat thickness directly above the greatest depth of the ‘eye’ muscle (C). Both of these were more precise predictors than ‘eye’ muscle width and depth. Accounting for breed, either by allowing for different intercepts or completely different regression lines, did increase the proportion of variation in tissue weights explained by carcass weight and J or C, but to a small and, it was considered, commercially unimportant extent. This was despite differences in conformation between the breeds, reflected in this work by smaller ‘eye’ muscles in the ewe than the ram breeds and also in maturity, which might have been expected to influence tissue, including fat, distribution.

The results indicate that breed differences in partition and distribution within and between the carcass fat depots in sheep are smaller than those between the carcass and intra-abdominal fat depots.
Induction of puberty in gilts 2. The effect of boars on maintenance of cyclic activity in gilts induced to ovulate with pregnant mare's serum gonadotrophin and human chorionic gonadotrophin
Authors: Paterson A. M. , Lindsay D. R.
Published: September 2010

In two experiments prepubertal gilts were injected with a combination of 400 international units pregnant mare's serum gonadotrophin and 200 international units human chorionic gonadotrophin. The gilts were housed either in contact with or isolated from mature boars. Data were obtained of ovarian activity determined immediately after gonadotrophin treatment and at the anticipated time of the second oestrus.

All treated gilts ovulated in response to the treatment and 83% displayed oestrus. Ovulation rate varied both within and between experiments, in experiment 1 the range being 7 to 19 corpora lutea and in experiment 2, between 5 to >30 corpora lutea. Four distinct types of behaviour were observed at the time of the second cycle: ovulation associated with oestrus; ovulation without oestrus; oestrus but no ovulation; and a return to a prepubertal state with no oestrus or ovulation. The presence of boars enhanced the maintenance of cyclic activity. Overall, more gilts displayed a second oestrus (33/39 v. 19/41, X2 = 11·2, P<0·001), and more had a second ovulation (32/39 v. 24/41, X2=4·2, P<0·05) when boars were run with the gilts.
Induction of puberty in gilts 3. Ovulation, plasma oestradiol and progesterone in gilts injected with pregnant mare's serum gonadotrophin and human chorionic gonadotrophin
Authors: Paterson A. M. , Martin G. B.
Published: September 2010

Nineteen prepubertal gilts were injected with a combination of 400 international units pregnant mare's serum gonadotrophin and 200 international units human chorionic gonadotrophin. Blood was sampled throughout the ensuing oestrous cycle and assayed for progesterone and oestradiol-17β.

Eighteen gilts had vulval development consistent with oestrus within 5 days and had ovulated by day 12. Oestradiol levels in the plasma were elevated between days 2 and 6, and progesterone concentration increased between days 6 and 10 due to the establishment of functional corpora lutea. Progesterone concentration in the luteal phase was related to ovulation rate (r = 0·72, P<0·001).

Three types of cyclic activity followed the luteal phase and a characteristic hormone profile was established for each. Five gilts exhibited a second ovulation accompanied by signs of oestrus. They had a second peak of oestradiol around days 24 to 26 and a subsequent rise in progesterone concentration. Four gilts displayed vulval development at this time but did not ovulate. A peak of oestradiol was detected. The remaining gilts did not display oestrus, nor did they ovulate. Oestradiol and progesterone concentrations remained basal in these gilts. The ovaries of prepubertal gilts treated with this combination of gonadotrophins produce normal patterns and levels of oestradiol and progesterone. Cyclic activity is not always maintained, probably due to differences in the maturity of the hypothalamic-pituitary-ovarian axis.
A note on seasonal changes in litter size of Finn × Awassi ewes
Authors: Amir D. , Schindler H. , Genizi A.
Published: September 2010

The twinning rate of Finn × Awassi ewes in a breeding management system which included three breeding periods a year, namely, June, September and December-January, was studied in animals mated at their natural or induced oestrus.

A similar number of lambs per ewe lambing was obtained from the ewes mated either at the induced oestrus in June or September, or at their natural oestrus in December. A significant decrease was found in the twinning rate of the ewes mated in January after hormone treatment. The conception rate was highest in the ewes mated in December-January.
A note on the variability of hormone concentrations in twice-weekly blood samples taken from heifer calves during the first 110 days of life
Authors: Hart I. C. , Morant S. V. , Roy J. H. B.
Published: September 2010

To assess the variability of hormone values obtained from calves at an early age, plasma concentrations of prolactin, growth hormone, insulin and thyroxine were measured in blood samples taken twice-weekly from seven heifers maintained under commercial conditions during their first 110 days of life. With the possible exception of thyroxine, there was considerable variation in the concentration of each hormone in each animal throughout the period of sampling, thus indicating that twice-weekly sampling was inadequate for investigating differences in hormonal concentrations between cattle of different production potential. Although there were trends in the pattern of plasma hormone concentrations as the calves progressed from the pre-ruminant to ruminant states, few of the changes during the pre-weaning, weaning and post-weaning periods were consistent between animals.
Comparison of terminal sire breeds for growth and carcass traits in crossbred lambs
Authors: Cameron N. D. , Drury D. J.
Published: September 2010

Performance records for the progeny of matings of Oxford, Texel, Texel-Oxford, Charollais, Charmoise and Meatlinc rams with crossbred ewes were analysed. The lambs, born from 1980 to 1982, were randomly allocated to three slaughter groups: (1) slaughter at fixed weights of 36 and 38 kg for ewe and castrated lambs; (2) slaughter according to estimated fat cover; (3) slaughter at a fixed age of 4·5 or 5·5 months with half-carcass dissection. The analyses were by least squares and effects were fitted for terminal sire breed, breed of maternal grand sire, year of birth, age of dam at lambing, birth-rearing type and sex of lamb and all two-way interactions. The results followed a well-established pattern where weight for age rankings were constant from birth, through weaning, to slaughter. Progeny of Oxford rams were the heaviest, followed by Texel-Oxford, Meatlinc and Charollais, Texel and Charmoise in that order. Lambs sired by rams of low mature weight reached a fixed weight at a later age than those sired by rams of high mature weight. They also reached a similar degree of fat cover at an earlier age and at lighter weights than the larger breeds. The carcass traits indicated that Texel crosses had a higher lean and lower fat proportion than would be expected from their growth and mature weight.

The comparative performance of crossbred lambs from 15 terminal sire breeds was assessed, at the same proportion of carcass subcutaneous fat, by combining the results of three experiments.
A note on the relationship between undernutrition and luteinizing hormone release in the ewe
Authors: Crump Alison D. , Rodway R. G. , Lomax M. A.
Published: September 2010

The effects of a moderate level of undernutrition on the release of luteinizing hormone (LH) at oestrus and after luteinizing hormone releasing hormone (LHRH) treatment was investigated. Plasma levels of glucose, non-esterified fatty acids (NEFA), cortisol and prolactin were also investigated.

During the early breeding season 10 mature ewes were placed on either a maintenance (M) or a restricted (R) diet. After 50 days of dietary treatment their oestrous cycles were synchronized and blood samples were taken over the oestrous period. Eight days later LHRH was administered and blood samples were taken for the following 6 h.

After 50 days of treatment mean body- weights were 66 (s.e. 4) and 53 (s.e. 3) kg, and mean body condition scores were 3·5 and 2·0 for the M and R groups respectively. The pre-ovulatory and LHRHinduced LH peaks were similar in both groups as were the prolactin profiles. However, plasma NEFA levels were elevated and glucose and cortisol levels were reduced in the restricted group.

It is concluded that the reduction in energy intake achieved in this experiment, although sufficient to cause significant metabolic changes had no effect on the release of LH either at oestrus or after LHRH treatment.
A notes on nutrient digestibility and nitrogen retention in ewes fed whole grains of triticale, wheat and maize
Authors: Felix A. , Hill R. A. , Winchester W.
Published: September 2010

Two digestion trials were conducted using sheep fed whole grains of triticale, wheat or maize on an equal amount or an isonitrogenous basis. Nine ewes were used in a 10-day collection period for each trial. Both trials consisted of three treatment groups of three animals each. Each ewe received daily either 1200 g of a diet containing 740 g (per kg diet) triticale, wheat or maize (trial 1) or 900 g of a diet containing 650, 650 and 600 g (per kg diet), respectively, of the above grains. Digestibilities of various nutrients, dry matter and organic matter were generally similar among treatments. However, apparent digestibility of crude fibre was significantly higher for ewes fed triticale than for those fed maize or wheat diets.
Feeding of dairy cows: a survey of the concentrate usage of high yielding cows during the winter
Authors: Rickaby C. D.
Published: September 2010

(1) A survey was conducted to determine the concentrate usage during the winter (1962–63) of each of 125 high-yielding dairy cows. The bulky foods consumed by each cow were also recorded.

(2) On average the cows were given 3.64 lb. concentrates per gallon of milk produced, and their intake of starch equivalent in excess of that needed for maintenance was 2.54 lb. per gallon. The margin per month (milk sales less cost of concentrates) was £14 13s Od.

(3) The implications of the results of the survey are discussed in relation to the feeding of dairy cows.
The interpretation of genotypic ratios in domestic animal populations
Authors: Robertson Alan
Published: September 2010

If, from a population, samples of individuals are drawn with a small number of parents, it is shown that there will be on average an apparent excess of heterozygotes above the number calculated from the gene frequency in each sample. The apparent proportional excess is where M and F are the number of male and female parents. This is independent of the number of alleles at the locus concerned. The use of the usual significance tests will also be affected. If analyses are done within herds of domestic livestock, particularly cattle, the number of sires in use at any time is likely to lead to a bias of a size which is of biological importance. The conditions under which genotypic ratios can usefully be examined are discussed.
The use of station and field tests for the improvement of milking performance in dairy cattle. I. Variation in milk yield and butterfat in test station records
Authors: Hinks C. J. M.
Published: September 2010

A study of variation in milk yield and butterfat has been undertaken, using the test station records of almost 5 000 first-calf cows of three dairy breeds.

The general object of the investigation was to provide a background for a more comprehensive examination of the important productive characteristics of dairy cattle, and of the use of different sire-testing procedures for their improvement; the specific object was to consider the possible causes of large sire components and heritability estimates that have been observed in all analyses of test station production data, and the reasons why the station and field tests of a bull do not always correspond.

Large heritability estimates for milk yield, fat yield and fat percentage were obtained in the Danish Red and Black Pied breeds, but the corresponding estimates in the Jerseys (0·31, 0·48 and 0·58 respectively) were similar in size to the values normally obtained for these traits in field data.

The pre-selection of heifer recruits to the stations, and breed differences in the intensity of selection applied to the productive characteristics, were considered and dismissed as causes of abnormal sire components, in the light of results obtained from field data which indicated that the heritability of milk yield in the Jerseys was not lower than in the other two breeds (0·26, 0·37 and 0·36 in Danish Reds, Black Pied and Jersey).

It was suggested that differences between records made in test stations and records made in farmers' herds may be caused by differences in milking efficiency, by differences in culling practices in the two environments, and by the effects of age, season at calving and contemporaneity. Other investigations have established that these factors may have a large influence on the variance components of the production traits, and all of them would repay further investigation.
Time taken to mature in relation to mature weight for sexes, strains and species of domesticated mammals and birds
Authors: Taylor C. S.
Published: September 2010

The relationship between mature weights of domestic species and the times they take to mature in live weight is extended to breeds and strains within a species and to sex differences within a breed or strain. Results based on the Gompertz growth curve are found to be essentially the same as those based on Brody's growth curve. Both confirm the relationship of proportionality between the time a species takes to mature in live weight and its mature weight raised to the power 0·27 or some power close to this. The overall weighted average coefficient was 0·273 ± 0·029 for Brody's (1945) growth curve data and 0·276 ± 0·030 for the Gompertz growth curve data of Laird (1966). The weighted average coefficients of 0·358 ± 0·098 for strains within a species and 0·343 ± 0·049 for sexes within a strain, although not significantly greater than 0·27, suggest that a coefficient of ⅓ might be a better value to adopt when the relationship is confined within species.

Birds as a class matured significantly more rapidly than expected from their mature weight and mammals significantly more slowly. Body temperature could account for this class difference in maturing time but not for deviations of individual species or strains. Relative to their mature weight, some species appeared to take much less time to mature than others, with possibly a 2- to 3-fold genetic difference between extremes of the range.

The main use of the relationship obtained lies in providing a ‘metabolic’ age scale on which animals or species can be examined for differences in immature physiological characteristics such as maturing time, body composition or efficiency of food utilization independently of differences in adult size.
Studies on the nutrition of ruminants. 3. The substitution of soya bean meal by urea in diets containing ground roughage and cereal
Authors: Swan H. , Lamming G. E.
Published: September 2010

Thirty-two yearling Friesian steers were used in a 2 × 2 factorial experiment. The treatment variables were source of supplementary nitrogen and physical form of the diet. The diets contained 30% ground barley straw, ground maize, a nitrogen supplement, and minerals and vitamins. Urea was compared with soya bean meal as the nitrogen supplement and both diets were given as cubes or meal. There was no significant difference between treatments in daily live-weight gain, feed intake or commercial carcass acceptability.

Digestibility trials with wethers showed the apparent digestibility of nitrogen and dry matter of the diet containing urea to be significantly lower than that of the diet containing soya bean meal (nitrogen 72·8 ν. 76·3, P < 0·001; dry matter 70·2 ν. 75·3, P < 0·01). The results are discussed in relation to the digestibility of the diets used, the source of supplementary nitrogen and the physical form of the diet.
The use of station and field tests for the improvement of milking performance in dairy cattle. III. Breed differences in the yield of milk and butterfat from the fore and rear quarters of the udder
Authors: Hinks C. J. M.
Published: September 2010

The analysis was concerned with selective advantage as a possible cause of differences between breeds and individual animals in the relative proportions of milk obtained from the fore and rear quarters of the udder.

Danish Jersey cattle were found to yield a significantly higher proportion of milk from the fore quarters than Danish Red and Danish Black Pied cattle (47% ν. 45% and 44% respectively).

Very strong genetic relationships between the proportion of milk obtained from the fore quarters and lactation yields of milk and butterfat (rg = 0·92, 0·85) in the Jerseys, and correspondingly weak genetic relationships in the other two breeds, suggest that breed differences have arisen as a result of selection for productive performance operative upon different genetic relationships between production and the process controlling the partition of milk in the udder. It is suggested that differences between the breeds are likely to increase in the future.
A note on difficult birth in Scottish hill flocks
Authors: Gunn R. G.
Published: September 2010

An exceptionally high incidence of difficult birth (29% of ewes giving birth to single lambs) in a Cheviot sub-flock in 1957 was reported by Gunn and Robinson (1963). To analyse some of the factors contributing to variation in the incidence of difficult births, observations were made on three farms over a seven-year period from 1958 to 1964. The farms are Sourhope, Roxburghshire, in the Cheviot Hills, with 1000 Cheviot and 350 Blackface ewes on predominantly Festuca-Agrostis, Nardus and Molinia pastures, with no regular provision of supplementary feed; Glensaugh in the East Grampians in Kincardineshire, with 550 Blackface ewes on predominantly heather (Calluna) pasture on free draining ground, with regular provision of supplementary feed during winter and spring; Lephinmore on Loch Fyne in Argyll, with over 600 Blackface ewes on mixed pasture mostly overlying peat, with limited provision of supplementary feed during winter and spring. Further details are given in the H.F.R.O. report (1958).
Food intake and live-weight gain comparisons of Bos indicus and Bos taurus steers on a high plane of nutrition
Authors: Rogerson A. , Ledger H. P. , Freeman G. H.
Published: September 2010

1. The voluntary dry-matter and water intakes of indigenous and exotic cattle on high plane rations have been compared under similar conditions of management.

2. At similar live weights, exotic cattle have a much higher feed intake
relative to maintenance than indigenous cattle.

3. Water intake was closely related to dry-matter intake, irrespective of live weight, and varied only very slightly between the two types of cattle.

4. Exotic cattle were more than twice as efficient as indigenous cattle in converting feed into live-weight gain. It is suggested that this is largely a reflection of the increased feed intake, relative to maintenance requirements.

5. Stage of maturity, degree of fatness and their relation to conversion
efficiency are discussed.
Factors affecting the shape of the lactation curve in cattle
Authors: Wood P. D. P.
Published: September 2010

The lactation curve in cattle has been explained by the expression
yn = Anbe-cn
where yn is the average daily yield in the nth week, and A, b, and c are constants. In general, in a sample of 859 Friesian lactations recorded during 1964–65 daily yield was depressed during the winter months (18·8% in January) and stimulated during the spring (14·7% in May) to an extent which was independent of the stage of lactation. Winter calvers on the other hand tended to produce more in total lactation than spring calvers (14·5% for animals calving in November as opposed to those calving in April).

Using a suitable technique it is possible to predict month by month output from a cow, or herd, accurately enough to furnish a basis for forward planning.
The association of food conversion ratio, age at slaughter and carcass quality in pigs fed ad libitum
Authors: Owen J. B. , Morton J. R.
Published: September 2010

Data from a boar progeny testing scheme based on ad libitum feeding were analysed to test the hypothesis that the resultant correlations of food conversion ratio with related factors would differ from those found under conditions of restricted feeding.

The results support the hypothesis, showing that the primarily genetic correlations derived from boar effects for growth and conversion ratio, are lower than those reported elsewhere for restricted feeding. It was also shown that these primarily genetic correlations could vary between breeds, the leanness associated with rapid growth in Wessex not being found in Large White, and that the correlations due to residual effects containing a greater environmental component varied widely from test to test.

It is concluded that the parameters used in the design of a genetic improvement scheme should be derived specifically for each breed and feeding system. However, if the marked variability in phenotypic correlations noted here is generally applicable, this could present a difficult problem in the design of pig improvement programmes with multiple objectives.
Effect of unwilted and wilted silages and hay, supplemented with different amounts of concentrate, on live-weight gain of calves
Authors: Bartholomew P. W. , McLauchlan W. , Chestnutt D. M. B.
Published: September 2010

Three experiments were carried out to investigate the effect of different forage types on the performance of male British Friesian calves up to 6 months of age. Unwilted and wilted silages were compared in all experiments, and in experiment 1 hay was also compared with the two silages. All the forages were compared at different levels of concentrate supplementation ranging, in different experiments, from none to ad libitum.

Calves fed wilted silage consumed 490, 90 and 200g/kg more forage dry matter respectively than those fed unwilted silage in the three experiments but this extra intake was generally not reflected in an increased rate of gain. Hay which was of lower digestibility than silage gave significantly lower live-weight gain. Quantities of silage consumed at an early age were small, with a mean daily intake over the first five weeks of 0·13 kg dry matter. Concentrate reduced silage dry-matter intake by 0·49 kg/kg concentrate dry matter consumed. Estimated mean concentrate intake required to achieve a daily gain of 0·75 kg in 1- to 6-month-old calves with silage offered ad libitum was 0·83 kg dry matter.
Reproduction in the gilt 4. The effect of rearing gilts with contemporary castrated males or intact males on the attainment of puberty
Authors: Cole D. J. A. , Dyck G. W. , Nathan S.
Published: September 2010

Sixty-six Landrace × (Landrace × Large White) gilts were allocated at 70 days of age to one of three rearing treatments of housing with gilts, contemporary castrated males or contemporary intact males. Half the experiment was completed in winter and half in spring. At 159 days of age all gilts were subjected to a change of pen and, from 160 days of age, daily exposure to mature vasectomized boars. The rearing treatments had a small but significant effect on the time interval from boar exposure to puberty, with gilts housed with gilts averaging 8·9 days to puberty compared with 7·1 days and 7·4 days for gilts housed with castrates and boars, respectively (p < 0·05). In addition, there was a seasonal effect on the time interval to puberty. Gilts receiving mature boar exposure during the winter months had a longer interval to puberty than gilts exposed to boars during the spring (8·8 days v. 6·9 days; P < 0·01). These results indicated no habituation effects of gilts housed with contemporary males but, rather, the possibility of a slightly earlier induction of puberty.
The effects of birth weight and level of feeding in early life on growth and development of muscle and adipose tissue in the young pig
Authors: Campbell R. G. , Dunkin A. C.
Published: September 2010

Forty-two piglets were used to study the effects of heavy and light birth weight, and of four levels of feeding, ranging from 37 to 91 g dry matter per kg M0 75 per day, on growth between 5 days of age and 6·5kg live weight, and on body composition, and the cellularity of muscle and subcutaneous adipose tissue, at the latter weight. The effects of birth weight and level of feeding to 6·5 kg on performance between 6·5 and 11 -5 kg, and on body composition at 11·5 kg, were also investigated.

Light birth weight piglets grew more slowly to 6·5 kg than those of heavy birth weight (P< 0·05). However, birth weight had no effect on food conversion efficiency or on body composition.

Each increment in feeding level resulted in increases in growth rate (P< 0·01), body fat content (P< 0·01) and average fat-cell diameter (P< 0·01) at 6·5 kg, but in decreases in body protein and water (P< 0·01).

The weight of the m. semitendinosus at 6·5 kg was unaffected by either birth weight or level of feeding. However, the deoxyribonucleic acid content of the muscle at both 6·5 and 11·5 kg was less in light birth weight piglets fed at the lowest level prior to 6·5 kg (P< 0·05). These piglets also exhibited poorer growth performance subsequent to 6·5 kg than their heavier birth weight counterparts.

Nevertheless, piglets of both light and heavy birth weight, fed at the lowest level to 6·5 kg, grew faster and more effficiently between 6·5 and 11·5kg (P< 0·05), and were leaner at 11·5kg than those previously fed at the highest level (P< 0·01). Average fat-cell diameter at 11·5kg was also less in pigs fed at the lowest level prior to 6·5kg (P< 0·01). Total deoxyribonucleic acid in subcutaneous adipose tissue at 11·5kg was unaffected by either birth weight or level of feeding prior to 6·5 kg.
A note on growth rates and maturation rates in beef bulls
Authors: Webster A. J. F. , Ahmed A. A. M. , Frappell J. P.
Published: September 2010

Values for weight and age of beef bulls at stud have been used to describe growth beyond the point of inflexion of the growth curve. Using the concept of ‘metabolic age’ it was shown that the maturation rate in Aberdeen Angus and Friesian bulls was close to a reported interspecies mean value. Hereford and Charolais bulls both matured relatively rapidly. Variation between individuals within a breed was consistent with the hypothesis that it is possible to select for rapid growth rate without necessarily selecting for an increase in mature size.
A note on a computer program for independent culling
Authors: Saxton A. M.
Published: September 2010

Calculating optimal truncation values for independent culling selection procedures has been difficult. Previously published charts took much of the tedium out of the calculations but the charts are difficult to read with accuracy and are not available for all possible parameter values. Therefore a computer program was written to calculate optimal truncation values for two-trait independent culling, with the option of restricting the genetic change of one or both traits. The program is described and an example of its use is given.
Calving dates and subsequent intercalving intervals in New Zealand beef herds
Authors: Morris C. A.
Published: September 2010

The calving dates of spring-calving cows in New Zealand Angus and Hereford herds, taken from 350 and 240 herd-years respectively, and the intercalving intervals (CI) of cows in 95 Angus and 73 Hereford herds have been summarized. The relationships of each CI with the calving date which initiated it were also analysed. Results for each breed were analysed taking account of district, herd, year and cow age (in years), a total of 35 890 Angus and 22 397 Hereford records being used. The first-calving date (FCD) was identified for each herd-year, and 0·82 of Angus and 0·75 of Hereford cows were recorded as calving within 60 days of the FCD. On a herd basis, proportionately only 0·27 of Angus and 0·15 of Hereford herds had calving spreads of 80 days or less (defined as the time from the FCD to the last calving date). With barren years ignored, the CIs of cows averaged 370 days (Angus) and 368 days (Hereford). Two-year-old cows had on average a CI of 12 (Angus) or 7 days (Hereford) longer in 1974-75 than older cows, and the differences were both 12 days in 1975-76. Regression analyses showed that, on average, the later the calving date within a herd-year and age group, the shorter the subsequent CI. For cows calving early in the first year, the CI increased by 7 days for Angus and 5·4 days for Herefords for each 10 days before the mean calving date for the breed. There were significant effects of district and cow age on the regression estimates. The overall regressions were not consistent with those derived from British beef industry data.
Effect of daylength at birth and lunar phase on the occurrence of first oestrus in beef heifers
Authors: Greer R. C.
Published: September 2010

Data records from 556 beef heifers which included age at first oestrus (AFE) were used to test the null hypotheses: 1) daylength at birth is not a determinant of AFE in beef females; and 2) there is not an association between the day on which first oestrus occurred and the lunar phase.

The effect of daylength at birth was measured by forming a variable, X1 where X1 = sine (X1′ 360/365·25)°, and including it among the set of variables in a multiple linear regression equation with AFE as the dependent variable. The resultant estimated coefficient on X1 was -3·617 with a standard error of 21·32, and led to the conclusion that daylength at birth was not a factor which affected AFE in this group of beef heifers.

The lunar phase hypothesis was tested by forming the frequency distribution of the 556 observations of first oestrus over the 30-day lunar cycie. The chi-square test was applied with the theoretical (hypothesized) distribution being the uniform distribution. The value of the test statistic was such that the null hypothesis would not be rejected even with an a value approaching 0·50. Additionally, coefficients of autocorrelation calculated for lag phases of 7, 14 and 21 days were quite small. Thus it was concluded that the occurrence of first oestrus was uniformly distributed over the lunar cycle.
Responses in lamb performance from selection on sire 100-day weight
Authors: Cameron N. D. , Smith C.
Published: September 2010

Forty-one Texel and Texel-Oxford sires were selected over 5 years (1978-82) on high and low adjusted 100-day weight from 174 ram lambs artificially reared from birth and performance tested. The correlated responses to selection were measured in 1103 crossbred progeny, out of an experimental group of crossbred ewes, the progeny being naturally reared in field conditions. Hierarchical analysis of variance was performed, fitting the usual fixed effects and interactions. Co-heritabilities (rAh2h2; rA is the genetic correlation between traits with heritabilities h12 and h22) were estimated from offspring-parent regression and from the realized responses to selection. The selection differentials achieved (1·70 standard deviations in 100-day weight between high- and low-weight sires) were lower than expected, due to mating difficulties, mortality and other requirements for the stock. The co-heritabilities for growth traits were generally positive but small (mean 0·08; s.e. 0·08). Though not statistically significant, lambs slaughtered at a fixed weight from the high-weight rams were slaughtered earlier with lighter and leaner carcasses, as expected. Similarly, lambs slaughtered according to fat cover from high-weight rams were slaughtered later with heavier slaughter and carcass weights. Generally, the co-heritabilities for carcass traits were not significantly different from zero for either slaughter group. On the basis of these results, selection on ram 100-day weight with artificial rearing may not offer any advantage over natural rearing in the improvement of lamb growth and carcass traits.
Bovine growth hormone in lambs: effects on carcass composition and tissue distribution in crossbred females
Authors: Butler-Hogg B. W. , Johnsson I. D.
Published: September 2010

Thirty-two Dorset Down × Finn Dorset female lambs were reared from 8 to 20 weeks on an ad libitum concentrate diet. They comprised four groups of eight lambs, one on each of the following treatments: (1) control, no injections; (2) daily subcutaneous injection of 0-1 mg bovine pituitary growth hormone (bGH) per kg live weight; (3) daily subcutaneous injection of 1 mg bromocriptine mesilate (Br); (4) daily injections of both bGH and Br at the same rates as treatments (2) and (3).

There were no important differences in carcass composition or tissue distribution between the +bGH and +bGH+Br lambs or between the control and +Br lambs. The +bGH lambs (+bGH and +bGH+Br lambs pooled) contained significantly greater proportions of lean and bone compared with the −bGH lambs (control and +Br lambs pooled). Although carcass composition was altered by bGH treatment, the distribution of individual tissues (lean, bone and fat) was not influenced significantly.

Carcass quality was improved markedly by bGH treatment: subcutaneous fat depth was reduced and the area of the m. longissimus lumborum increased. +bGH carcasses would be ranked one fat class less on the Meat and Livestock Commission fatness scale than −bGH carcasses at the same carcass weight.
The use of station and field tests for the improvement of milking performance in dairy cattle. IV. Culling effects in herd and station records
Authors: Hinks C. J. M.
Published: September 2010

The effects of culling, natural wastage and different correction and exclusion procedures on estimates of lactation parameters have been examined in test station records of 1042 Danish Red cows. A total culling rate of 20% was applied to the initial material, of which 11% represented obligatory culling for disease, injury and infertility and 9% ‘paper’ culling for performance at four different stages of lactation.

Exclusion and correction of short records generally resulted in overestimates of the sample mean and underestimates of the selection differential produced by culling. In all instances, the variance of the sample prior to culling, and the loss of variance attributable to culling, was underestimated in samples containing short or corrected records.

It was concluded that field data cannot provide material suitable for objective studies of selection and that a reappraisal of the effects of age, lactation, season, etc., in the controlled conditions of test stations may well be justified. An absence of culling in test stations contributes to the large estimates of variance and heritability characteristic of station material.
The development and structure of, and seasonal change in, the coat of some Wiltshire sheep
Authors: Ryder M. L.
Published: September 2010

Coat and skin samples were taken monthly from three Wiltshire ewes for two years, and then fortnightly between the spring equinox and the autumn equinox of 1968.

The fleece comprised kemp and wool, having a weight of 1·1 kg and a length of 50 mm. In summer all the primary fibres had a latticed medulla, and although the secondaries were smaller than the primaries, they were relatively coarse and often medullated, over one-third having a latticed medulla at the peak period. The overall mean S/P ratio was 3·5.

Follicle development was studied in four lambs from birth to 84 days. Only 27% of the secondaries lacked fibres at birth, and all had fibres at 14 days. There was a trend of increasing medullation in the primary fibres. Shedding primary follicles were seen from birth onwards, and shedding secondaries from 28 days, although obvious casting of the birth coat did not begin until 84 days (at the beginning of June).

There was a basic seasonal cycle of follicle activity starting in March and lasting until September; inactivity began in September, reached 100%, and continued at this level until March. Subsidiary cycles suspected from the monthly samples were confirmed by the fortnightly samples. Thus peaks of inactivity in June and August separated three cycles of growth of two months duration. Only 80% of the primaries and 50% of the secondaries became inactive in June, with 50% of the primaries and 30% of the secondaries, in August.
Testing regression models for pig feeding systems
Authors: Dent J. B. , English P. R. , Raeburn J. R.
Published: September 2010

Regression equations have been tested relating average daily gains in pigs to average daily intake of crude protein, lysine, and TDN for each of three growth stages. The tests were based on output contour curves representing 1 lb, 1·4 lb and 1·75 lb live-weight gain per day in the three stages. On each contour, while crude protein intake was held constant, points were selected to represent the economically optimum combination of lysine and TDN intakes, a ‘high energy-low lysine’ combination and a ‘low energy-high lysine’ combination. For the latter two points, least cost mixes of feed ingredients were computed. Four feed mixes were computed at the economically optimum combination of lysine and TDN intakes. Comparisons were made between the performance of pigs given the six different mixes to assess the validity both of the slope of the output contour and its position and to examine the influence on growth performance of the ingredient specification of diets formulated to the same nutrient levels.

Using the six diets formulated on each contour, 12 feeding systems were developed all of which theoretically would take the pig from 50 to 200 lb in the same number of days. Six of these systems maintained the same diet type for each period; the others involved a change of diet type at least once during the three stages of growth. Diets formulated to meet the economically optimum combination of nutrients based largely on maize and groundnut meal stimulated inferior daily gains compared with alternative formulations. Both diets with a larger percentage of their lysine supplied from synthetic sources (the economically optimum combination based on maize and groundnut meal, and a low energy-high lysine combination) led to inferior daily gains. Pig performance was generally poorer than expectation, particularly from 50 to 150 lb live weight.

No differences could be attributed to differing ingredient composition in equi-nutrient diets. Similarly, no significant differences in growth rate were found between those systems which maintained a constant diet type throughout the three stages of growth. Pigs on systems which involved a change in diet type from one stage of growth to another grew in general slower than those pigs which had a fixed-diet type throughout.

Pigs on both diet combinations with a high percentage of weatings (a high cost formulation and a low energy-high lysine combination) had the best carcass results.
Beef production from grass and silage with autumn-born calves. 1. The influence of grazing intensity on efficiency of herbage utilization and live-weight gain of cattle
Authors: Wilkinson J. M. , Prescott J. H. D.
Published: September 2010

1. Two experiments are described in which groups of 12 autumn-born calves were strip-grazed at different intensities. In Experiment 1 (1966), ‘standard’ and ‘high’ grazing intensities were compared. In Experiment 2 (1967), ‘standard’ and ‘low’ intensities were compared. In both experiments the same meadow fescue—ryegrass ley provided 0·24 ha per head for grazing and conservation; herbage surplus to grazing requirements was conserved as silage.

2. The grazing season was divided into three parts according to the type of grazing, and estimates were made of daily herbage allowances, herbage quality, efficiency of herbage utilization and the live-weight gain of the cattle.

3. Grazing intensity was regulated by controlling daily herbage allowances by strip-grazing. Within grazing seasons, differences in grazing intensity had little effect on the digestibility of the herbage dry matter on offer. Dead herbage accumulation was low (10%) in the early and late parts of the season, but rose to 25% in mid-season.

4. The efficiency of herbage utilization was estimated in three ways: from sample cuts of herbage on offer and refused; from measurements of herbage intake; and from feeding standards for maintenance and gain. Efficiency was highest for the ‘high’ group of Experiment 1 and lowest for the ‘low’ group of Experiment 2. The validity of efficiency estimates is discussed in relation to measurements of pasture yield, herbage intake and the assessment of the nutrient requirements of growing cattle.

5. Live-weight gain over the whole season was 0·59 and 0·89 kg/head per day for the ‘high’ and ‘standard’ groups of Experiment 1, respectively. In Experiment 2, the ‘low’ and ‘standard’ groups gained weight at 0·95 and 0·84 kg/head per day, respectively.
Crossbreeding Sinhala cattle with Jersey and Friesian in Ceylon
Authors: Wijeratne W. V. S.
Published: September 2010

A crossbreeding trial was conducted in the hot wet tropical zone of Ceylon at Karagoda-Uyangoda. Sinhala cows were mated to Jersey, Friesian and Sinhala bulls. A few reciprocal matings were done with the Jersey breed.

The milk yields of the Friesian crosses were higher than those of the corresponding Jersey crosses which were higher than those of the Sinhala. The ½ Sinhala ½ Friesian also had a longer lactation and larger body size than the Jersey cross or purebred Sinhala. A decline of about one-third of the milk yield of the F1was evident in the F2generation.

The liability to perinatal mortality increased from the F1generation calves to F3calves.
A comparison of the performance of suckled lambs with lambs weaned at seven weeks of age and either grazed or given concentrates
Authors: Rutter W.
Published: September 2010

1. Seventy-two Blackface ewes with 96 Greyface (Border Leicester ♂ × Blackface ♀) lambs were allocated to three groups. Twenty-four ewes with 32 suckling lambs were set-stocked on 2·4 hectares (ha) of grass (A); 32 lambs were weaned and set-stocked on 2·4 ha of grass (B) and 32 lambs were weaned, housed and given concentrates (C). Beef cows with calves were used to control the grass in the two grazing groups.

2. The average initial live weight of the lambs was 18 kg. Treatments had a significant effect on performance, the live-weight gains per lamb over the initial 35 days being 11·2, 9·1 and 5·9 kg for groups A, B and C respectively. The total gains over 70 days, when the suckled lambs (A) were weaned, were 17·6, 15·5 and 14·3 kg.

3. The total live-weight gain per ha from lambs and calves over 88 days was higher on treatment B than on treatment A. The lambs weaned on to grass took 9 days longer than the suckled lambs to reach a slaughter weight of 42 kg and had significantly poorer killing-out percentages.

4.The lambs given concentrates had an overall food conversion efficiency of 4·89 kg concentrates per kg live-weight gain.
The voluntary intake and utilization of roughage–concentrate diets by sheep. 1. Concentrate supplements for hay and straw
Authors: Crabtree J. R. , Williams G. L.
Published: September 2010

Four levels of a proprietary concentrate (0, 100, 200 and 400 g/day) were offered to Welsh Mountain ewe lambs receiving hay or straw ad libitum for 14 weeks. The apparent digestibility of the energy and nitrogen in the various diets was determined in a concurrent digestibility trial.

The voluntary intakes of the straw and hay dry matter when given alone were 242 and 451 g/day respectively (28·4 and 49·2 g/kg W0·73 per day). Straw intake increased with an increase in concentrate feeding up to a level of 25% concentrate in the total dry matter and then declined. Hay intake declined linearly with increasing concentrate level (3 g/day decline per unit increase in the percentage of concentrate). In each case the total intake of dry matter and digestible energy increased with an increase in concentrate level.

There was a positive within-treatment relationship between initial live weight and voluntary intake, an additional 0·019 Meal ME/day being consumed per kg increase in live weight. Within treatment groups lambs consuming relatively more food also made relatively higher weight gains. Estimates based on published standards of the metabolizable energy intakes required to produce the live weight changes observed on each treatment were considerably higher than the intakes recorded in the trial.