bluuebunny/crossref_metadata_2025_split huggingface dataset:
The seasonality of reproductive performance of Merino sheep in Britain
Authors: Tempest W. M. , Boaz T. G. 
Published: September 2010

SUMMARYA study has been carried out to determine the length of the breeding season and the feasibility of lambing twice a year in Merino sheep in Britain.Six groups of 18 ewes were exposed to rams at monthly intervals, and twice per year, from April 1969 to June 1970. A well-defined breeding season, from August to January, was found, and its shortness, linked with the inability of the ewes to conceive immediately post partum, prevented lambing twice in the year.
The influence of age at first calving and winter feeding management as yearlings on calf production from beef Shorthorn cows
Authors: Bernard C. S. , Fahmy M. H. , Lalande G. 
Published: September 2010

SUMMARYThe effects of age atfirstcalving (2 v. 3 years) and the winter feeding management as yearlings (roughages v. roughages supplemented with meal) on conception rate, calving performance (survival and weights) and lifetime production were studied on 76 beef Shorthorn cows bora from 1956 to 1958 at the Lennoxville Research Station. Conception rates averaged 89 %, and were not influenced by treatments. Calf mortality from birth to weaning was 1·5 and 0·6% higher among the calves out of the cows which had calved first at 2 years old and cows not supplemented, respectively, but the differences were not significant. Calves born to cows calving first at 2 years were 0·8 and 7·7 kg (P>0·05) lighter at birth and weaning respectively than those born to cows calving first at 3 years of age. The effect of feeding regime of the cows as yearlings on the weights of calves at birth and at weaning was non-significant.In cows calving annually up to 8 years of age in this trial the lifetime production of those calvingfirstat 2 years of age was greater by 40 kg than of those calving first at 3 years of age, although the advantage was greater in earlier years.
Onset of oestrus and fertility of dairy heifers and suckled beef cows treated with prostaglandin F2α
Authors: Hafs H. D. , Manns J. G. , Drew Bridget 
Published: September 2010

SUMMARYSuckled cows (average 70 days post partum) and British Friesian dairy heifers (13 to 24 months of age) were injected intramuscularly with prostaglandin F2α (PGF2α) on two occasions 12 days apart, to synchronize oestrus and ovulation. The cattle were inseminated twice, 70 and 88 hr after the second injection.Injections of 20, 30 or 40 mg of PGF2α were equally effective in 59 heifers; after the first injection, 11 failed to show oestrus during the following 10 days and 10 began oestrus within 36 hr. The majority of the heifers (59%) began oestrus during the 3rd or 4th day after the first injection of PGF2α. After the second injection of PGF2α, all but two heifers showed oestrus and the majority (88%) began oestrus in 3 to 6 days.Injections of 30 or 60 mg of PGF2α were equally effective in 66 suckled cows; after the second injection of PGF2α, 68% of the cows began oestrus from the 3rd to the 6th day but 10 (15%) cows failed to show oestrus.Fertility was highest among heifers and cows which began oestrus during 3 to 5 days after the second injection of PFG2α, 54% of the treated heifers and 42% of the treated cows calving during the expected intervals. Nineteen of the 20 control heifers were mated and 25 of 33 control cows were observed in oestrus and inseminated during 3-week or 25-day breeding periods. Eleven (55%) control heifers and 14 (42%) control cows calved during the expected intervals. Thus, fertility of the treated cattle inseminated at predetermined intervals after PGF2α was equivalent to that in the controls.
The performance of early-weaned calves offered a high dry-matter silage supplemented with concentrates or dried grass
Authors: Marsh R. 
Published: September 2010

SUMMARYIn two experiments a high dry-matter silage (36·8% DM) was offered ad libitum, together with a supplement of a conventional concentrate or cobs of dried grass, to young British Friesian castrated male (steer) calves. The silage was readily acceptable to the calves and was preferred to the dried grass. Intakes of silage DM were significantly higher (P<0·001) when supplemented with dried grass than when supplemented with concentrates, but daily gains were significantly (P<0·001) lower by 0·15 kg. The lower daily gains supported by the silage/dried grass diet were related to lower intakes of digestible organic matter (DOM); efficiency of utilization of silage/dried grass DOM was similar to that of concentrate/silage DOM. The results are discussed in relation to recommended levels of production for calves in a semi-intensive beef system.
The comparative performance of purebred and crossbred boars in commercial pig production
Authors: Lishman W. B. , Smith W. C. , Bichard M. , Thompson R. 
Published: September 2010

SUMMARYAn investigation was undertaken to evaluate the crossbred boar per se, and also to assess the value of including the American Hampshire into a first-cross sire. Groups of three boars were placed on each of 20 farms. Each group contained a purebred white (Landrace or Large White), a crossbred white and a crossbred Hampshire boar. Co-operators were asked to obtain at least six litters by each boar, record their performance to weaning, and provide a sample of the progeny of each boar to be reared under standard conditions to slaughter at 90 kg live weight. Breeding of the boars did not affect either the level or variability of litter performance. Differences in performance and carcass traits between the progeny of purebred and whitecross boars were found only for ‘eye-muscle’ area and fat depth ‘C’. Pigs sired by Hampshire-cross boars had carcasses which were 2% shorter than those from white boars.
A note on the effect of the discount rate and length of the accounting period on the economic value of genetic improvement in cattle populations
Authors: Cunningham E. P. , Ryan Joan 
Published: September 2010

SUMMARYThe discounted gene flow method was used to study the effect of varying financial discount rates and accounting period on the present value of the genetic merit conferred by each insemination.Over the range from 8% to 16%, each 1% increase in the discount rate reduces the value of the dairy and beef consequences of an insemination by about 5% and 4% respectively, Virtually all of the economic benefit arising from an insemination is complete within 20 years, with about 90% of it being realized in the first 10 years and 98% in the first 15 years.
Genotype-environment interaction in milk production under Danish and Bulgarian-Czechoslovakian conditions
Authors: Petersen P. H. 
Published: September 2010

SUMMARYFirst lactation records from 971 daughters of 93 Red Danish Milk-breed bulls exported as pregnant heifers from Denmark to 4 Bulgarian and 21 Czechoslovakian herds were analysed and compared to results from corresponding half-sib groups under Danish field progeny tests. Average butterfat production in East European tests was 75% of that in Danish tests.The results indicate that the true genetic variance and the heritabilities for milk yield, fat content and butterfat yield are higher under the Danish conditions than under the corresponding East European conditions. The genetic correlations between the two environments are estimated to be 0·91, 0·97 and 0·79 for milk yield, fat content and butterfat yield, respectively. Because of insufficient correction for environmental effects, these estimates are considered to be lower than the true parameters.It is concluded that selection of proven sires in the Danish main population for use in the small East European subpopulations will result in a higher genetic improvement rate than will sire testing and selection within the subpopulations.
Effects of breed of cattle on energy requirements for growth
Authors: Chestnutt D. M. B. , Marsh R. , Wilson J. G. , Stewart T. A. , McCullough T. A. , McCallion T. 
Published: September 2010

SUMMARYWith the object of comparing the energy requirements of cattle of different breeds a total of 108 animals, representing three maturity types, were individually fed at two levels of intake over three 12-week periods commencing at 250, 375 and 500 kg live weight in a co-ordinated experiment. The three breeds compared were Aberdeen Angus cross, Hereford × British Friesian and British Friesian. Animals were offered a 50:50 hay: concentrate ration at two levels of feeding; one level was designed to give 0·7 kg gain daily and the other 75 to 80% of this intake.Though the relative performance of breeds differed at the three centres, overall average live-weight gain did not differ significantly between breeds. Feed conversion efficiency dropped from 8·55 kg dry matter per kg gain in the first period to 16·95 kg in the third period, but differences in conversion ratio between breeds were not significant.Carcass measurements taken at slaughter immediately after the third test period indicated higher killing-out percentages and higher fat percentages in the Angus cross than in the British Friesian with Hereford × Friesian intermediate. Differences in energy needs for gain among the three breeds, predicted by apportioning ME intake to maintenance and gain using a multiple regression technique, were greater than differences calculated from carcass composition and published energy requirements for fat and protein deposition. The limitations of the use of the multiple regression technique for this purpose are discussed.
Effect of dietary energy content at different stages of growth on performance of intact male cattle
Authors: Levy D. , Holzer Z. , Ilan D. 
Published: September 2010

SUMMARYSix groups of Israeli-Friesian intact male calves were studied over growth periods of 200 to 300 kg, 300 to 400 kg, and 400 to 500 kg live weight. Different ratios (85: 15, 70: 30 and 50: 50) of concentrate to roughage were compared. Two groups received the same ratio (85: 15 or 70: 30) throughout the experiment. In the other groups, the proportion of concentrates was progressively increased or decreased.Live-weight gain in the first period ranged from 759 to 1013 g/day, i n the second period from 1095 to 1239 g/day and in the third period from 831 to 922 g/day. Overall rate of gain was highest in the groups receiving a constant ratio, regardless of the ratio used. Increasing the proportion of concentrates as the calves became heavier, which is common practice in Europe, did not improve performance and decreasing the proportion reduced performance. Only at 200 to 300 and at 400 to 500 kg live weight did a concentrate percentage higher than 50 result in improved performance.Dry-matter intake, relative to live weight, was higher with a ratio of 70: 30 than with one of 85: 15 or of 50: 50 in each period. Animals on a constant ratio of concentrates to roughage gave the most efficient conversion of feed energy to live weight.There were no significant differences in dressing percentage or in carcass composition.
Growth and carcass characteristics of weaned single-suckled calves slaughtered on achieving slaughter condition or 8 or 16 weeks later
Authors: Broadbent P. J. 
Published: September 2010

SUMMARY1. Weaned single-suckled calves (castrates) were housed at 260·7 kg live weight. Six genotypes, all two- or three-way crossbreds, were represented. A diet of bruised barley, wet distiller's grains, swedes and grass silage was offered until the required minimum live weight (363 kg) and body composition was reached. The cattle were then slaughtered (treatment A), or retained for 8 (treatment B) or 16 weeks (treatment C). During the period when treatment B and C animals were retained their diet was 53% bruised barley and 47% wet distiller's grains offered ad libitum.2. Live weights at slaughter were 418·2, 458·6 and 496·1 kg (P < 0·001), carcass weights 240·5, 266·2 and 295·7 kg (P < 0·001), and killing-out percentages 57·5, 58·1 and 59·6 (P<0·01) for treatments A, B and C respectively. Daily live-weight gain did not decline during the 8 or 16 weeks cattle were retained on treatments B and C.3. Retaining the cattle to slaughter points B and C caused increases in the percentage of low-value joints in the carcass, carcass fat percentage, dry matter and fat contents of the dissected m. longissimus dorsi; and decreases in the percentage of high-value joints, carcass lean and bone percentage, crude protein and ash contents of m. longissimus dorsi. The carcass composition was 55·6, 53·5 and 51·4% lean (P<0·001); 30·7, 33·3 and 36·2% fat (P<0·001); 13·7, 13·2 and 12·4% bone (P< 0·001) for treatments A, B and C respectively.4. The results are discussed in relation to the choice made by beef producers between slaughter and retention of cattle which have reached suitable live weight and condition for marketing.
A note on the use of condition scoring in commercial sheep flocks
Authors: Pollott G. E. , Kilkenny J. B. 
Published: September 2010

SUMMARYThree aspects of body condition scoring in commercial sheep flocks were examined. Ewes in 44 flocks were condition scored when the rams were introduced to the flock and their subsequent lambing performance was recorded. The pooled regression coefficient obtained for the relationship between individual ewe condition score and litter size was 0·29±0·0243 with a squared correlation coefficient of 1·96%.Between flock differences accounted for 57% of the variation in ewe condition score. Within the breeds recorded average flock condition score at mating was related to the number of live lambs born per 100 ewes mated. This relationship is shown for several breeds of ewe. A further 27 flocks were involved in a trial to evaluate the effectiveness of a specific use of condition scoring. Ewes were scored 6 to 8 weeks before mating and in 12 flocks the ewes in poor condition were given an improved plane of nutrition. These ewes showed an improvement of 12 lambs born per 100 ewes mated over ewes not given better nutrition.
Breed differences in body composition of equally mature sheep
Authors: McClelland T. H. , Bonaiti B. , Taylor C. S. 
Published: September 2010

SUMMARYSheep from the Soay, Finnish Landrace, Southdown and Oxford Down breeds were serially slaughtered at about 40, 50, 60 and 70% of their estimated mature body weight. Breed and sex comparisons were made at these degrees of maturity. Large differences were found in the weight of muscle, fat and bone, total muscle ranging from a mean of 3·3 kg in the Soay to 13·0 kg in the Oxford Down; the corresponding range for dissected fat was 1·2 to 9·2 kg.Most of the breed and sex differences observed at the same degree of maturity disappeared when expressed as a percentage of body or carcass weight. Thus both sexes had almost the same body and carcass composition in terms of fat, muscle and bone percentage. There were breed differences in fat percentage, with the Soay significantly less fat than the other breeds. Total muscle as a percentage of body weight was remarkably close to 28·5% in all breeds in both sexes, and at all four stages of maturity.
Prediction of the energy requirements for growth in beef cattle. 2. Hereford × British Friesian steers given dried grass or barley
Authors: Webster A. J. F. , Smith J. S. , Crabtree R. M. , Mollison G. S. 
Published: September 2010

SUMMARY1. Hereford × British Friesian castrate male cattle, growing from about 80 to 500 kg, were given equal amounts of metabolizable energy (ME) from dried grass pellets or from a pelleted diet of barley and a protein supplement. Two animals on each diet were fed close to appetite (High) and two at a level mid-way between maintenance and appetite (Medium). The rations for all animals were reduced to approximately maintenance for 4 weeks on three occasions equally spaced throughout the experiment. Measurements of energy and nitrogen balance were made for each animal at intervals of 6 to 8 weeks. Total body-water content was estimated from D20 dilution at intervals of 110 kg live weight.2. Values for the metabolizability of the gross energy of the dried grass and barley/protein diets were 0·55 and 0·67.3. Metabolic heat production during growth was closely related to body weight to the power 0·75. Predicted basal metabolism was 395 kJ/kg 0·75 per 24 hr.4. Estimates of the net efficiency of utilization of ME for growth were unaffected by small variations in the exponent of W used to describe the effect of body size on heat production. Both diets were utilized above maintenance with a net efficiency close to 0·62.5. Nitrogen balance trials seriously overestimated nitrogen retention. Gains in fat-free body mass estimated from D2O dilution were combined with calorimetric measurements of energy retention to predict the relationship between energy retention and weight gain. The agreement between observed and predicted live-weight gain was good at the lower body weights and on the lower ration. For fatter animals eating the high ration at higher body weights, live-weight gains were less than predicted.
Concentrations of plasma hormones in relation to placental retention in Karan Swiss cows during and after induction of parturition with dexamethasone and stilboestrol dipropionate
Authors: Prakash B. S. , Madan M. L. 
Published: September 2010

ABSTRACTFive Karan Swiss cows were allowed to calve spontaneously and served as controls (Group A), while another 10 were induced to calve about 1 month prior to expected term using either 25 mg dexamethasone alone (Group B) or 25 mg dexamethasone in combination with 25 mg stilboestrol dipropionate (Group C). Blood samples were collected prior to, and for 50 days following, parturition for subsequent hormone analysis, and observations were made on the occurrence of retained placentae.Parturition was successfully induced in all treated cows within 72 h of drug administration. Placental membranes were retained for 24 h in all treated animals and were manually removed in the farm veterinary clinic. No incidence of placental retention occurred in control cows.Mean plasma oestradiol-17β in control cows showed a gradual rise from days 30 to 5 pre partum, followed by a sharp increase to peak value 1 day before calving. The rise in mean oestradiol-17β levels in the 2 days before parturition in controls was significantly greater than that recorded for the treated animals. A precipitous drop in plasma oestradiol-17β level occurred following parturition in all groups, with the levels staying low for the rest of the sampling period. Drug administration to animals in groups B and C resulted in a rapid and significant drop in plasma progesterone concentrations to a level similar to that for control animals at parturition. Subsequently, the plasma progesterone remained low in all treatment groups. Mean plasma cortisol levels showed a significant but transient increase at calving in control cows, but were suppressed for at least 48 h following drug administration in treated cows before exhibiting a rebound phenomenon to reach high values after calving.It is concluded that for normal placental expulsion, oestradiol-17β levels are more critical than progesterone, and that the rise in oestradiol-17β and fall in progesterone levels pre partum must be gradual.
Effect of fermentation on compositional changes of antibiotic milk and performance of calves fed fermented antibiotic milk
Authors: Hadjipanayiotou M. , Georghiades E. 
Published: September 2010

ABSTRACTCompositional and acidity changes in fermented normal or antibiotic milk, and the effects of feeding jch milk on the growth, food conversion efficiency and overall health of dairy calves were studied, Type of milk (normal or antibiotic) did not significantly affect pH, lactose, crude protein, fat and free (H3—N content of milk. Lactose content and pH values decreased with time whereas free NH3—N lcreased. Higher room temperatures were associated with lower pH; values below 5 were obtained after weeks of fermentation in winter, 2 weeks in spring, 1 week in autumn and less than 1 week in jmmer. Overall pH values and lactose content declined until week 4 and remained constant thereafter, calves fed fermented antibiotic milk gained less weight from birth to weaning than those on fresh milk, put post-weaning growth rates were similar. Incidence of scouring was higher among calves fed antibiotic lilk, but no deaths occurred. Milk intake was similar, and consumption of dry food (pre and post eaning) differed slightly.
Inter-age correlations of body weight, weight gain and food intake within and between breeds of cattle
Authors: Thiessen R. B. 
Published: September 2010

ABSTRACTIn a multibreed experiment, 292 heifers from 25 British cattle breeds were fed a standard pelleted diet ad libitum from 12 to 72 weeks of age. Inter-age correlations involving body weight, weight gain, average daily food intake and cumulated food intake were measured across traits at the same age and within and across traits at ages separated by an interval of 12, 24, 36 and 48 weeks. Within-breed correlations were phenotypic but between-breed correlations were genetic.The between-breed inter-age correlations involving body weight, cumulated intake and average daily intake were all very high (range 104 to 0·94) and declined only gradually as the intervening age interval increased from 12 to 48 weeks. Inter-age correlations involving weight gain were lower but usually above 0·7. The within-breed correlations by contrast were invariably lower and declined much more rapidly as the age interval increased. Although the between-breed and within-breed correlations differed in magnitude there was a similarity in their overall pattern.For breed samples, body weight at young ages provided very accurate rankings at later ages for body weight, cumulated intake and average daily intake. Body weight was almost as reliable as food intake itself for predicting cumulated intake.For individuals within breeds predicted rankings at later ages were not very accurate for body weight or cumulated intake and they became worse as the age interval increased. Neither weight gain nor average daily intake could be predicted with any reliability.Inter-age correlations while dependant on age interval did not depend on age itself in the case of body weight and cumulated intake, although they were age-dependant for weight gain and to a lesser extent for average daily intake. Reciprocal correlations between body weight and cumulated intake were very symmetrical whereas those involving weight gain and daily intake were asymmetrical.
A note on the fleece characteristics of Oxford Down sheep
Authors: Ryder M. L. , Walker M. F. 
Published: September 2010

ABSTRACTFleece measurements were made in a closed flock of Oxford Down sheep being maintained by random mating. The original 20 ewes were sampled in 1970 and another 20 of the 30 ewes were sampled in 1980. Staple length, mean fibre diameter and secondary/primary follicle ratio were similar at the two sampling times. There were more inactive follicles in 1980 and more follicles with multiple fibres, but the differences were not significant. The appearance of some medullation and pigmentation in 1980 could have an environmental rather than a genetic cause. Follicles intermediate between primaries and secondaries were observed, and in all fibres the bilateral structure was clearly visible.