bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of intake by cattle from degradation characteristics of roughages
Authors: Ørskov E. R. , Reid G. W. , Kay M.
Published: September 2010

Five different straws consisting of two varieties of winter barley, two varieties of spring barley and one variety of winter wheat were chosen due to differences in degradation characteristics determined by using nylon bags incubated in the rumen of cattle and describing the straw using the equation: p = a + b (1 – e–ct). To increase variation in degradability, batches of the same straws were also treated with anhydrous ammonia in a sealed oven.

The straws were subsequently offered ad libitum to groups of steers given a daily supplement of 1·5 kg concentrate and untreated straws were supplemented with urea. The dry-matter intake (DMI) of the straws varied from 3·4 to 5·7 kg/day, the digestible DMI from 1·4 to 3·5 kg/day and growth rate from 106 to 608 g/day.

By using multiple regression of a, b, c from the exponential equations characterizing degradability of the straw, the correlation coefficients with DMI, digestible DMI and growth rate were 0·88, 0·96 and 0·95 respectively.
A note on amino acid digestibility measured in pigs with pre-or post-valve ileo-rectal anastomoses, fed soya-bean, pea and meat meals
Authors: Green S.
Published: September 2010

It is known that microbial activity in the hind-gut of pigs influences the amino acid composition of faeces (Mason, 1984), yet contributes little to protein nutrition (Just, Jørgensen and Fernández, 1985). This diminishes the extent to which amino acid digestibility determined by faecal collection from intact pigs adequately represents nutritional value. In order to minimize the interference of hind-gut microflora, pigs for digestibility trials have been surgically modified to create a by-pass of the large intestine by ileo-rectal anastomosis (e.g. Green, Bertrand, Duron and Maillard, 1987 and 1988). This involves transection of the ileum approximately 100 mm anterior to the ileo/caecal valve. The modification can be considered as an alternative to collecting digesta from cannulas fitted in the ileum. The attributes of ileo-rectal anastomosis are that all digesta, rather than spot samples, can be collected and the animals remain in good health for many months of trial work. There is, however, concern that because the anastomosis operation involves complete severance of the ileum, digestion in the ileum may be abnormal. Of particular concern is the by-pass of the ileo-caecal valve which is suspected to have a restraining rôle on digesta passage (Gazet and Kopp, 1964; Laplace and Borgida, 1976), and therefore a possible influence on digestibility. When using ileo-caecal valve, by fitting the anterior digesta, other workers have attempted to preserve a complete ileum, and functional ileo-caecal value, by fitting the anterior cannula immediately posterior to the valve (Laplace, 1986)
Effects of selection for divergent ultrasonic fat depth in rams on progeny fatness
Authors: Bennett G. L. , Meyer H. H. , Kirton A. H.
Published: September 2010

Fat depths of Southdown and Suffolk rams were ultrasonically measured several times prior to 18 months of age. Ultrasonic measurements were regressed on live weight and deviations from this regression were standardized and summed to select rams with high and low fat depth to produce crossbred progeny for slaughter. An average of 3·24 standard deviations separated high and low sires. Progeny were slaughtered at two ages to determine differences in carcass fatness and its development. A significant difference of 0·5 mm fat depth over the loin eye muscle was found between progeny of low and high sires. Progeny from Suffolk high sires had greater tissue depth over the rib and higher kidney fat weight than those from Suffolk low sires but differences were small or reversed in Southdown progeny. Low progeny had significantly less estimated carcass chemical fat than high progeny. Fat depth C increased less in low progeny between early and late slaughter ages. However, no difference in partition of carcass weight gain to fat weight gain was observed between high and low progeny. Differences in fat weight between high and low progeny, as well as between Southdown and Suffolk progeny, appeared to have occurred prior to the earlier slaughter age.
Influence of diurnally fluctuating high temperature on growth and energy retention of growing pigs
Authors: Giles L. R. , Dettmann E. Belinda , Lowe R. F.
Published: September 2010

Abstract The effects of two temperatures (thermoneutral, 22°C v. fluctuating high temperature, 35·22°C), four food levels (ad libitum and three levels of food restriction) on growth and energy retention of growing pigs (male and female) was investigated in a 2 × 2 × 4 factorial experiment involving 48 individually penned pigs from 20 to 50 kg live weight. A second experiment was conducted over the 50 to 80 kg liveweight range using a 2 × 2 × 3 design.

Mean daily digestible energy (DE) intake, daily gain, P2 backfat thickness, carcass fat proportion, total body energy retained and body energy retained as protein did not differ significantly between the temperature treatments in either experiment. Mean carcass protein proportion was greater at 35·22°C than at a constant 22°C.

With pigs given food ad libitum during the 50 to 80 kg phase, an increase in temperature from 22°C to 35·22° reduced daily DE intake by 4·1 MJ (38·9 v. 34·8 MJ or 300 g food per day), reduced energy retention by 2·3 MJ/day (15·6 v. 13·3 MJ/day), and increased carcass protein proportion by 11 g/kg (142 v. 153 g/kg).

There was a significant interaction between the effects of sex and temperature on P2 backfat thickness over both live-weight ranges. Female pigs housed at 35·22°C had 2·6 mm less P2 backfat at 50 kg (13 v. 15·6 mm) and 2 mm less at 80 kg (20 v. 22 mm) compared with females housed at 22°C. The P2 backfat thickness of male pigs did not vary at 50 kg (13·2 v. 13·5 mm) but when housed at 35·22°C males had 1·4 mm more P2 backfat at 80 kg (18·2 v. 19·6 mm).
Compensatory growth in cattle grazing different vegetation types
Authors: Wright I. A. , Russel A. J. F. , Hunter E. A.
Published: September 2010

Fifty-four Charolais-cross weaned suckled calves were used in an experiment to investigate the effects of feeding level during the post-weaning winter on their subsequent performance, when grazing different vegetation types in summer. During winter they were given grass silage and barley at one of three levels (low, medium and high). The winter live-weight gains were 0·50, 0·75 and 0·96 (s.e. 0·019) kg/day (P < 0·001) for the low, medium and high treatments respectively. During summer they grazed either a sown ryegrass pasture (S), a hill reseed (R) or part of an unimproved hill (H).

Live-weight gain during summer was inversely related to winter feeding level on all grazing treatments, the mean live-weight gains being 1·01, 0·79 and 0·65 (s.e. 0·027) kg/day (P < 0·001) for the low, medium and high winter feeding levels respectively. Summer treatment significantly affected performance, the live-weight gains being 0·88, 0·94 and 0·61 (s.e. 0·027) kg/day for the S, R and H treatments respectively. There was no interaction between winter and summer feeding treatment on live-weight gain. The organic matter intake was highest on the H treatment but the digestibility of herbage consumed was the lowest, resulting in the lowest digestible organic matter intake.

Similar and high levels of performance were obtained on sown ryegrass pastures and reseeded hill land, while unimproved hill vegetation supported only moderate levels of live-weight gain. Compensatory growth occurred when a wide range of vegetation types were grazed in summer.
Modifications to MOET nucleus breeding schemes to improve rates of genetic progress and decrease rates of inbreeding in dairy cattle
Authors: Woolliams J. A.
Published: September 2010

The effect of changes in the mating system on the rates of genetic progress and rates of inbreeding are considered for MOET nucleus breeding schemes. Methods are derived to calculate best linear unbiased predictors of breeding value in MOET schemes and the rate of inbreeding under selection. These are applied to different mating systems in which the numbers of sires and dams, and the number of offspring per sire and offspring per dam, remain constant.

Results showed that compared with nested mating systems, factorial mating systems in which the maternal half-sibs are produced instead of full-sibs, could increase genetic progress by 1·12-fold with no additional inbreeding. The increased progress arose through an increase in the selection intensity applied. The rates of inbreeding derived were found to be approximately double those estimated by the formula of Wright (1931) in the absence of selection.

In practice, even if a complete factorial system were to increase the generation interval and consequently reduce progress below that predicted, changes in the mating system avoiding this problem could be implemented that would be of immediate benefit.
Estimation of milk consumption curve parameters for different genetic groups of bovine calves
Authors: Mezzadra C. , Paciaroni R. , Vulich S. , Villarreal E. , Melucci L.
Published: September 2010

Milk consumption was estimated for crossbred suckled calves from birth to weaning during 2 years. Breed groups utilized were Aberdeen Angus (A) and Charolais (C) sires on Fl Angus-Hereford (and their reciprocals) dams in the 1st year and in the 2nd year, sires A and Nelore (Bos indicus) (N) were used on the same type of dam. The weigh-suckle-weigh technique was employed twice a day to estimate milk consumption on a weekly basis. Estimations were adjusted by least-squares for the effects of genetic group, week of estimation, and their interaction, with sex of calf and calf and cow weights in the week of estimation as covariables. Then a non-lineal regression equation of the form: y = b0Wb1e -b2b2W was fitted for each individual, where y = milk consumption and W = week of estimation. Curves for A and C were very close in their shape, but with a greater consumption (P < 0·01) for C. For the 2nd year, there were differences among A and N both in the shape of the curve and in consumption at the peak of lactation (P < 0·01). Differences in time to peak lactation were also found: for A calves, it was week 9, for C calves week 10 and for N calves week 3·8. The N group showed a sharper decline in persistency than the other groups, suggesting different patterns in milk consumption.
Prediction of the voluntary intake of grass silages by beef cattle 3. Precision of alternative prediction models
Authors: Rook A. J. , Dhanoa M. S. , Gill M.
Published: September 2010

The precision of a number of new models for predicting silage intake by beef cattle was investigated with independent data using the mean-square prediction error and compared with two previously published models (Agricultural Research Council, 1980; Lewis, 1981). The new models generally performed well relative to the previous models.

The new models included a number constructed using the technique of ridge regression which were shown to be consistently better predictors than the models obtained from the same estimation data by stepwise least-squares regression. Better prediction was also obtained by reducing the number of variables in the least-squares models below that required to maximize R2 in the estimation data. The poor performance of the least-squares models with the best R2 may be attributed to collinearity between the independent variates in the estimation data.

Most of the models considered overpredicted relative to observed intakes. This may have been the result of differences in breed type and management of the animals between the test data and the estimation data used to construct the models, that is the use of the models with the test data involved a degree of extrapolation.

It is concluded that ridge regression and deletion of variables offer a positive step forward in intake prediction compared with models based on maximizing R2 in the estimation data. However, further work is needed to clarify the effect of factors such as breed and rearing system on intake and to clarify the usefulness of various fibre measures in intake prediction. A number of new models are proposed which utilize a range of input variables thus allowing flexibility in their use in practical situations.
The dietary energy values of soya-bean oil, tallow and their blends for growing/finishing pigs
Authors: Wiseman J. , Cole D. J. A. , Hardy B.
Published: September 2010

Two fats, soya-bean oil and tallow, were blended in the ratios 70: 30, 50: 50 and 30: 70. The ratios of unsaturated to saturated fatty acids (U/S) of the blends were 3·18, 2·08 and 1·49 respectively; values for soya-bean oil and tallow were 6·69 and 0·93. These five fat sources were each included into a basal diet at levels of 40, 80 and 120 g/kg. The digestible (DE) and metabolizable (ME) energy together with the apparent fat digestibility (AFD) of the experimental diets were measured in a metabolism trial based upon four 4 × 4 Latin squares using 16 gilts of 30 kg initial live weight. Linear equations relating dietary DE and ME values to level of inclusion of fat were extrapolated to 1000 g/kg to obtain values for the fats. DE values for soya-bean oil and tallow were 38·06 and 34·16 MJ/kg respectively. Corresponding data for ME were 35·63 and 32·53 respectively. These figures were used to calculate values of the mixtures. Data thus derived did not differ significantly from those determined directly, indicating that there was no synergism between the two fats. DE values of fats determined as the product of AFD of fats and their gross energy followed similar trends. The majority of the increase in values of fats was associated with a change in the U/S ratio from 0·93 to 2·08.
Rumen degradation of straw. 10. Consistency of differences in nutritive value between varieties of cereal straws
Authors: Ørskov E. R. , Shand W. J. , Tedesco D. , Morrice L. A. F.
Published: September 2010

The consistency of differences between varieties in nutritive value of cereal straws was tested over 3 years consecutively for nine varieties of spring barley and 10 varieties of winter wheat straw and over 2 years consecutively for 12 varieties of winter barley and six varieties of oats. For all varieties there were large year-to-year differences in nutritive value measured by ruminal degradation characteristics using the nylon bag technique. For spring barley there were large differences between varieties and the correlations between varieties in different years were mostly in excess of r = 0·90 for 48-h degradability and maximum potential degradability. For winter wheat the correlations between varieties for different years were lower but mostly significant. For the winter barley differences between varieties were less, but even so differences between varieties in different years were significant. For oats differences between the varieties were small and there was no significant correlation within varieties between years. The results suggest that the nutritive value of cereal straws is generally consistent between years and is a characteristic that could be improved by selection.
Expected consequences of the segregation of a major gene in a sheep population in relation to observations on the ovulation rate of a flock of Cambridge sheep
Authors: Owen J. B. , Whitaker C. J. , Axford R. F. E. , Ap Dewi I.
Published: September 2010

A simple model was derived relating the phenotypic effect (g) of a major gene to observed values of the population mean and variance for a trait, at specified values of the major gene frequency and at specified basal values of the population mean and variance (in the absence of the major gene). This model was applied to a total of 549 observed values of ovulation rate in ewes of the Cambridge breed at Bangor under a range of assumptions. The mean values of ovulation rate were 2·44 for 243 ewes of 1 year of age and 37·54 for 306 ewes of 2 and 3 years of age with a coefficient of variation for both age sets of 0·50.

The results indicate a minimum value for g, in this data set, of 1·07 for 1 year old and 1·72 for 2 and 3 year old ewes. The results are also consistent with a frequency value in the region of 0·3 to 0·4, with the absence of dominance and with a reasonable concordance with Hardy-Weinburg equilibrium. The results also indicate that the value of g varies according to the background phenotype since it is lower for younger as compared with older ewes.
Changes in the body composition of beef cattle during compensatory growth
Authors: Wright I A. , Russel A. J. F.
Published: September 2010

Forty-two weaned suckled Charolais-cross steers were used to measure changes in body composition during compensatory growth in growing cattle. Six cattle were slaughtered initially and the remaining 36 allocated to either a low level of feeding to 350 kg live weight followed by a high level (LH) or a high level of feeding throughout (HH). Above 350 kg live weight, food intake on both treatments was the same at any given live weight. Six cattle were slaughtered from each treatment at 350, 400 and 450 kg live weight. From initial live weight (259 kg) to 350 kg, live-weight gains were 0·45 and 0·78 kg/day for the LH and HH treatments respectively (P < 0·001). From 350 to 400 kg live weight, live-weight gains were 1·35 and 0·98 kg/day (P < 0·01) for the LH and HH cattle respectively, while from 400 to 450 kg live weight there was no significant difference (1·38 v. 1·20 kg/day). The LH cattle contained less fat in the empty body than the HH cattle at 350 kg (118 v. 153 g/kg; P < 0·05) and 400 kg live weight (117 v. 169 g/kg; P < 0·01), but at 450 kg there was no significant difference between treatments. From 350 to 400 kg live weight the composition of the empty body-weight gain was 663 g water, ' 108 g fat and 216 g protein per kg in the LH cattle and 422 kg water, 311 g fat and 173 g protein in the HH cattle. From 400 to 450 kg live weight the equivalent figures were 491, 291, 156 g/kg for the LH cattle and 744, 67 and 203 g/kg for the HH cattle. The results demonstrate that following a period of food restriction the empty body-weight gain of cattle initially comprises increased proportions of protein and water and a reduced proportion of fat compared with unrestricted cattle when both are given the same amount of food and compared at the same weight. There then follows a second phase in which the proportion of fat increases and the proportions of protein and water decrease.
The influence of index selection for improved growth and carcass characteristics on appetite in a population of large white pigs
Authors: Smith W. C. , Ellis M. , Chadwick J. P. , Laird R.
Published: September 2010

Correlated genetic changes in the level and pattern of average daily food intake (ADFI) were evaluated n i a population of pigs under index selection over an 11-year period. Performance testing was carried out in single sex groups of two or three full-sibs over the live-weight range 27 to 87 kg on an ad libitum feeding regime. The selection index incorporated live-weight gain, ultrasonic backfat thickness and a group food conversion ratio. Samples of boars from a contemporary control line were used to measure genetic change over time. Cumulated correlated responses in ADFI for boars and gilts showed considerable variation between years but the values were always negative and tended to increase up to year 7 but increased no further from then on. Thus, in year 11 the cumulated responses for ADFI in boars and gilts were -0·25 (s.e. 0·06) kg (P < 0·001) and -0·19 (s.e. 0·05) kg (P < 0001) respectively, the corresponding regressions of cumulated response on year number being — 0012 and — 0·017 kg. The relationship between food intake and live weight was compared in samples of boars and gilts from the selection line (S) and boars from the control line (C) during the final year of the study. The regression of ADFI on live weight for the two boar lines differed in intercept but not in slope with S line boars consuming, on average, 0·23 kg/day less meal than the C line boars over the test period. The regression equations for S line boars and gilts differed in slope and elevation with gilts consuming relatively more food daily up to around 60 kg live weight and less subsequently.
Effect of litter size on the milk production, blood metabolite profiles and endocrine status of ewes lambing in January and April
Authors: Rhind S. M. , Bass J. , Doney J. M. , Hunter E. A.
Published: September 2010

Milk yields and blood metabolite and hormone profiles of a total of 40 Greyface ewes lambing in January or April and suckling single (S) or twin (T) lambs were determined. Ewes were given a fixed level of feeding throughout the first 10 weeks of lactation. Milk yields were measured weekly. Pooled blood samples (six samples; 20-min intervals), collected at weekly intervals for the first 10 weeks of lactation, were assayed for glucose, non-esterified fatty acids (NEVA), 3β-hydroxybutyrate, urea, albumin, total protein, insulin, growth hormone (GH), cortisol, prolactin, thyroxine (T4) and triiodothyronine (T3). At weeks 2, 4 and 10 of lactation samples were collected at 20-min intervals for 8 h and assayed individually for insulin, GH, cortisol and prolactin. Mean daily milk yield was lower in S than in T ewes in January (1·93v.2·33 kg/day;P< 0·05) and April-lambing ewes (1·95v.2·28 kg/day; P > 0·05). Profiles of NEFA and 3β-hydroxybutyrate indicated that T ewes were mobilizing adipose tissue at a greater rate than S ewes. The higher milk yield and rate of fat mobilization in T ewes compared with S ewes was associated with lower overall mean insulin concentrations (3·37v.5·04 mil per I;P< 0·002) and higher GH (6·29v.2·77 μg/l;P< 0·001) and cortisol (7·04v.3·64 μg/l;P< 0·001) concentrations in the weekly samples. Differences between rearing groups in mean concentrations of T4 and T3 were generally small and not significant. Mean prolactin concentrations were much lower in the January- than in the April-lambing ewes (73·7v.270·2 μ/l;P< 0·001) but this difference was not associated with a difference in milk yield. Substantial increases in insulin and GH concentrations generally followed feeding but the post-prandial profiles were dependent on stage of lactation; while GH concentrations increased following feeding at weeks 2 and 4 of lactation, there was generally a decline in post-prandial concentrations at week 10. It is concluded that the patterns of insulin and GH secretion during the hours following feeding may be an important determinant of the rate of tissue mobilization and milk yield in ewes subject to differences in demand for milk created by differences in litter sizes.
Effect of parity and physiological state on intake, milk production and blood parameters in lactating mares differing in body size
Authors: Doreau M. , Boulot S. , Martin-Rosset W.
Published: September 2010

Voluntary food intake, milk production and blood characteristics were measured in mares between the 3rd month before foaling and the first 5 weeks of lactation. The effect of breed during pregnancy was determined using 15 light mares and eight heavy mares (522 and 763 kg live weight (LW) after foaling respectively). The effect of parity was studied on light mares (seven were primiparous and eight were multiparous). In lactation, only four primiparous and four multiparous light mares were retained. Diet consisted of 900 g hay and 100 g concentrates per kg and was offered ad libitum. Voluntary food intake in pregnancy was higher for heavy mares than for light mares: 15·2v.10·3 kg dry matter (DM) daily. This difference was explained by differences in LW, since DM intake was the same when expressed as a fraction of LW or metabolic weight (M). Energy and nitrogen supply exceeded requirements, in the same way for light and heavy mares. No significant variations in blood measurements were observed between light and heavy mares, except for glucose. Primiparous mares ate less DM than multiparous mares in pregnancy: 9·7v.10·8 kg DM (P > 0·05), significantly so relative to LW and M. DM intake per kg LW or M depended on the parity. This difference had no effect on blood measurements, except for acetate. During lactation, no other differences in voluntary food intake were observed with regard to parity, whatever the week of lactation. Milk yield was higher for multiparous mares than for primiparous mares (16·6v.14·6 kg daily). Gross energy of milk varied according to a similar pattern, principally because of variations in fat concentration (20·2v.16·5 g/kg for multiparous and primiparous mares respectively). Energy balance was significantly more positive for multiparous than for primiparous mares.
Selection for predicted carcass lean content in Scottish Blackface sheep
Authors: Bishop S. C.
Published: September 2010

Scottish Blackface sheep have been selected for either increased or decreased predicted carcass lean content at 20 weeks of age, using an index combining ultrasonic backfat depth and body weight. The index was designed to alter carcass lean content without changing body weight. After 4 years there have been large responses in the index and fat depth, the proportional difference between the divergent lines in fat depth is 0·28, but body weight and ultrasonic muscle depth have not changed between the lines. The realized heritability for the index is 0·45. Heritabilities for the index, ultrasonic fat depth, body weight and ultrasonic muscle depth, calculated using multivariate restricted maximum likelihood, are 0·47 (s.e. = 0·14), 0·39 (s.e. 0·13), 0·23 (s.e. 0·12) and 0·36 (s.e. 0·14), respectively. The selected lines will be used to investigate relationships between carcass lean content, viability and maternal performance under the harsh environmental conditions encountered in the Scottish hill environment.
The performance of dairy cows offered drinking water of low or high salinity in a hot arid climate
Authors: Bahman A. M. , Rooket J. A. , Topps J. H.
Published: September 2010

Brackish well water (BW) containing 3574 mg total dissolved solids (TDS) per I was compared with desalinated water (FW, 449 mg TDS per I) as a source of drinking water for dairy cows in the hot arid conditions of Kuwait. Friesian-Holstein cows in early lactation were given daily, 12 kg cereal-based concentrate, 12 kg fresh lucerne and 4 kg senescent date palm leaves for 196 days with the experimental treatments being either BW or FW (four cows per water type). Dry matter and water intakes were not affected by water type (P > 0·05). Cows offered BW gained slightly more weight (P > 0·05) than cows consuming FW. Although overall milk yield and composition was unaffected by water type, the decline in milk yield as the experiment progressed was significantly (P< 0·05) less for cows offered BW. Cows offered BW tended to have higher concentrations of minerals and thyroid hormones in plasma than cows offered FW. It can be concluded that water containing 3574 mg TDS per I was an acceptable source of water for dairy cows.
Genetic analyses of cow lifetime production up to 12 mating years in crossbred beef cattle
Authors: Morris C. A. , Baker R. L. , Cullen N. G. , Hickey S. M. , Wilson J. A.
Published: September 2010

A total of 1088 females of 14 breed groups (Angus and Hereford purebreds, and 12 first-cross groups) were evaluated over two locations for lifetime survival, numbers of calvings, numbers of calves weaned and cow lifetime records of calf survival. These traits are known to be related to a cow's lifetime productivity. The animals were part of the Ruakura Beef Breed Evaluation, designed to compare the growth and carcasses of steers, and the reproductive and maternal performance of females of different breed groups. Data were from 4 birth years of females and 11 breed-groups at location 1, and from 5 and 10 respectively at location 2, with seven breed-groups common to both locations. Females were first mated as yearlings. Culling at ages 2·5 to 4·5 years was based mainly on females that were non-pregnant on two occasions, whereas in subsequent years any non-pregnant female was culled. At location 1, there was a maximum possible number of mating years of 22 for females in the 1st birth year, declining to a maximum of 9 for those in the 4th birth year; for each age group at location 2 there was a maximum of 9 mating years. The average cow survival (number of mating years) was 7·26 (s.d. 3·02) at location 1 and 5·81 (s.d. 2·31) at location 2, with a coefficient of variation similar at both locations and averaging 0·41. The performances from the poorest to the best breed groups had a 1·5-fold range for number of mating years and a 1·8-fold range for number of calvings and number of calves weaned. The heritability of number of mating years (no. = 150 sire groups) was 0·13 (s.e. 0·08), number ofcalvings 0·11 (s.e. 0·08), number of calves weaned 0·15 (s.e. 0·08), and calf survival as a cow trait 0·027 (s.e. 0·018). This last heritability increased to 0·093 if adjustment was made to the underlying liability scale. There was no significant effect of breed of cow on number of mating years, nor on number of calves weaned per 100 calvings at either location, whilst the effect was significant for number ofcalvings and for number of calves weaned per cow (P < 0·10). The wide breed variation pointed to opportunities for selection among breeds, whilst the low heritabilities suggested that within-breed selection will be slow unless early indicator traits can be found.
Effect of chemical structure of fats upon their apparent digestible energy value when given to growing/finishing pigs
Authors: Powles J. , Wiseman J. , Cole D.J. A. , Hardy B.
Published: September 2010

Four metabolism trials were conducted. Trials 1 and 2 (Tl, T2) investigated degree of saturation of fats (ratio of unsaturated to saturated fatty acids, U/S) on digestible energy (DE) content. Fats evaluated were rape oil (RO) and tallow (T) for Tl (U/S 15·67 and 0·97 respectively) and RO and palm oil (PO) for T2 (U/S 15·33 and 0·85 respectively). Three fats of intermediary U/S for each trial were produced by blending the two fats in proportions to give U/S of 3·18,2·08 and 1·49 in both trials. Trials 3 and 4 (T3, T4) investigated the effect of free fatty acid (FFA) content of fats on DE value. Fats were soya-bean oil (SO) and soya-bean acid oil (SAO) for T3 (FFA 6·2 and 626·0 g/kg respectively) and T and tallow acid oil (TAO) for T4 (FFA 44·3 and 818·2 g/kg fat respectively). Three fats of intermediary FFA for each trial were formed by blending the two fats in the ratios of 72:25, 50: 50 and 25: 75 in both trials. The FFA content of the blends were 161·2, 316·1 and 471·1 g/kg fat for T3 and 237·8, 431·3 and 624·7 g/kg fat for T4. All trials evaluated five fats by substitution, at 40, 80 and 120 g/kg into a basal diet, in a cross-over design, with 16 gilts of 25 kg initial live weight evaluating 16 diets over four time periods. Diets were offered for 10 days followed by a 5-day collection period using the marker to marker technique. Fat content of food and faeces, with methodology based on acid hydrolysis, allowed calculation of apparent digestible fat (AFD) of experimental diets. Analysis of variance gave effects of fats (P < 0·001 for Tl, T3 and T4 and P = 0·014 for T2), rates of inclusion (P < 0·001 for all trials), and fats × rates (P > 0·05, P > 0·05, P < 0·001, P < 0·01 for T1, T2, T3 and T4 respectively). Extrapolation of the function obtained by regressing AFD of diets (y) on rate of inclusion of fat (x) to × = 1000 generated values for the fats. The product of the coefficient of apparent fat digestibility of fats and their respective gross energies gave DE values for fats which were MJ/kg: T1 RO = 35·8 and T = 31·2; T2 RO = 36·7 and PO = 33·1; T3 SO = 374 and SAO = 32·8 and T4 T = 33·8 and TAO = 28·9. Data for fat blends intermediary between the two fats showed that DE improved exponentially as a function of U/S and that DE declined linearly with increasing FFA content.
Accounting for subpopulations in prediction of the proportion of lean meat of pig carcasses
Authors: Engel B. , Walstra P.
Published: September 2010

In a dissection trial in The Netherlands two subpopulations were distinguished: gilts and castrated males. The sampling scheme, which emphasizes extreme values for the proportion of lean meat in the carcass, was followed for the two sexes separately, to ensure sufficient accuracy for a comparison between them. Significant differences between the prediction formulae for the lean meat proportion for the two sexes were found. Since it is not possible to use separate prediction formulae for the sexes in Dutch slaughterhouses, the formulae had to be combined into one overall prediction formula. In this paper it is shown how the separate prediction formulae for the sexes may be combined, utilizing additional data, not involving dissection, which were easily collected on the slaughterline, at little extra cost. The method can be extended to cover any number of subpopulations. Two objectives can be achieved at the same time: subpopulations may be compared accurately on the basis of a stratified sample and from the results of the comparison an efficient, unbiased, overall prediction formula may be distilled.
A bivariate autoregressive model for estimation of prevalence of fasciolosis in cattle
Authors: Goodall E. A. , Menzies F. D. , Taylor S. M.
Published: September 2010

Fasciolosis is a serious economic disease of cattle and sheep with a worldwide distribution. In the annual control of the disease, it is vital that the issue of specific veterinary advice on the strategic use of control measures should be based on precise estimates of the levels of risk of the occurrence of the disease. This paper describes the construction of a mathematical model to forecast the level of risk of the disease in cattle in any year. The model has been developed in Northern Ireland using a computerized information database retrieval system for abattoir condemnation data. The information recorded by the system details the specific cause and location of all condemnations in cattle, sheep and pigs for all abattoirs in Northern Ireland. Analysis of a subset of these data (1976 to 1991) for cattle resulted in a univariate time series model for the recorded prevalence of condemnations due to fasciolosis in cattle livers. The overall mathematical forecasting model was constructed by regressing the residual terms of the univariate time series model with the corresponding time series of all the key meteorological variables. The best model (R2 =0·8) was obtained using the mean air temperature for the period fune to August inclusive. The model could be adopted for use in any region of the world where relevant abattoir condemnation and meteorological data are available.
Reproductive performance of sows entering stable and dynamic groups after mating
Authors: Simmins P. H.
Published: September 2010

Housing soivs in large groups is increasing in popularity but some group-housing systems may compromise subsequent reproductive performance. An experiment was designed to test this hypothesis using multiparous sows weaned at 21 ±2 days. Two treatments were studied: a stable group of 12 sows and a dynamic group of 18 sows. Both treatments had similar space allowances in the lying area (1·24 m2 per sow). Sows were allocated to treatment within 1 week of service and remained on treatment until after day 40 of pregnancy. Each stable treatment group remained unchanged, whereas sows were replaced weekly in the dynamic treatment. Sows were fed using a single electronic feeder for each pen. All sows were treated similarly for the rest of pregnancy. Eighty and 120 sows from the stable and dynamic treatments respectively completed pregnancy. Five second parity sows from the dynamic treatment were removed having suffered from aggression. The farrowing rate was 0·78 and 0·85 for stable and dynamic treatment sows respectively. The stable treatment sows had larger litters and a higher proportion of litters having 10 or more total piglets born (P < 0·01). The stable treatment showed a significantly heavier (P < 0·05) litter weight for total pigs born (16·9 v. 14.6 (s.e.d. 0·57) kg per litter). The parities were uneven so the data must be treated with caution. However, the results indicate that the present advice, that soivs should be housed in stable groups for the first 4 weeks of pregnancy, should remain unchanged.
Graded levels of Sesbania sesban and Leucaena leucocephala as supplements to teff straw given to Ethiopian Menz sheep
Authors: Bonsi M. L. K. , Osuji P. O. , Nsahlai I. V. , Tuah A. K.
Published: September 2010

Two experiments were conducted to investigate the effect of supplementation with fodder tree leaves on the utilization of teff straw. This ivas aimed at testing the hypothesis that forage supplements (e.g. sesbania) that disappear faster from the rumen compared with those that disappear slowly (eg. leucaena) may elicit higher intakes of the basal diet. Experiment 1 investigated the effect of level (i.e. 0,200,300 and 400 g/kg dry matter (DM) intake) of leaves of Sesbania sesban or Leucaena leucocephala on the utilization of teff straw fed ad libitum. Seven sheep were given the seven diets in four periods following a partially balanced (7 × 4) cross-over design. In experiment 2, teff straw alone or supplemented with graded levels of sesbania (250, 350 and 450 g/kg DM intake), were fed to 16 sheep in a completely randomized block design. Intake, degradability, nitrogen (N) utilization, particulate and liquid passage rates were estimated.

In experiment 1, protein source × protein level interaction was not significant. Supplementation increased intakes of total DM (P < 0-05), organic matter (P < 0·01) and N retention (P < 0·01) but had no effect on the intake of teff straw. Supplementation with sesbania, but not with leucaena, increased (P < 0·05) the apparent digestibility of DM. Both supplements increased (P < 0·05) the fractional rate of passage from the rumen. In experiment 2, graded levels of sesbania increased DM intake (P < 0·05), fractional rate of liquid outflow (P< 0·05) and tended to increase the rate of degradation. It was concluded that the effect of fodder tree leaves on roughage intake is a function of their disappearance rate from the rumen.
The effect of stage of breeding season or pre-mating oestrogen and progestagen therapy on fertility in ewe lambs
Authors: Beck N. F. G. , Davies M. C. G.
Published: September 2010

An investigation was conducted to determine the effect of mating at puberty or third oestrus or after pre-mating oestrogen and progestagen therapy, designed to mimic the changes that occur in plasma oestrogen and progesterone concentrations during the 1st, 2nd or 3rd oestrous cycles, on fertility in ewe lambs. Twenty-five ewe lambs were mated at puberty on mean date of 18 October and 21 were mated at third oestrus on 3 December. Of these, 28% and 81% of animals mated at puberty and third oestrus lambed, respectively (P < 0·05). A similar number of ewe lambs were mated within 24 h of ram introduction in the groups given one, two or three consecutive applications oestrogen and progestagen (25 μg oestradiol benzoate followed 48 h later by a progestagen pessary left in situ for days). Of the 43 corpora lutea, 21 were represented by viable embryos in the 37 animals holding to service after one application compared with 34 out of 46 corpora lutea in 40 animals given three applications (P < 0·05). Furthermore, embryo crown-rump length, embryo weight and amniotic sac width was greater (P < 0·05), on day of pregnancy, in animals given one compared with three applications of oestrogen and progestagen. These results demonstrate that fertility is improved in ewe lambs mated on third oestrus or after progestagen and oestrogen therapy designed to simulate three oestrous cycles.
An evaluation of two ultrasonic machines (Scanogram and Danscanner) for predicting the body composition of live sheep
Authors: Kempster A. J. , Arnall D. , Alliston J. C. , Barker J. D.
Published: September 2010

Scans of the m. longissimus and overlying fat at the 12th rib were taken, just prior to slaughter, on 254 lambs using the Scanogram and Danscanner ultrasonic machines. The lambs were from a ram breed trial and comprised six sire breed × five dam breed groups. Mean live weight at slaughter was 44·5 kg.

The precision with which scan measurements predicted comparable carcass measurements and carcass lean content (g/kg lean) was examined within groups with variation in live weight eliminated.

Residual s.d. for the prediction of carcass m. longissimus area from the corresponding scan measurement was 141 and 158 mm2 for the Scanogram and Danscanner respectively (s.d. of carcass m. longissimus area was 162mm2). Residual s.d. for the prediction of lean from the best combination of fat measurements was 32·0 for the Scanogram and 35·8 for the Danscanner (s.d. of lean was 38·5). M. longissimus did not increase the precision of lean prediction.

In a comparable evaluation of the Scanogram, involving 147 lambs, the residual s.d. for the prediction of lean was 24·0 (s.d. = 28·9).

The levels of precision obtained were low and it is debatable whether the ultrasonic techniques examined would be of value for carcass lean prediction in practical applications. They might be of use in selection programmes within nucleus flocks of the more important meat sire breeds or as an aid in experiments for differentiating between animals of widely differing composition.
A note on the effects of body fatness and level of food intake on the rate of fat loss in lactating ewes
Authors: Cowan R. T. , Robinson J. J. , McDonald I.
Published: September 2010

Data from three comparative slaughter experiments involving a total of 73 ewes were used to study the influence of body fat content at the start of lactation (X1 kg) and of metabolizable energy intake (X2, MJ/day), on the rate of loss of body fat by lactating ewes over the first 6 weeks of lactation (Y, g/day). The relationship was described by the equation:

Thus the rate of fat loss was greater for ewes with higher initial fat contents, but the differential became less as metabolizable energy intake increased. Since increases in body fatness depress food intake it was not possible to prevent loss of body fat during early lactation in fat ewes given high concentrate diets ad libitum. The likely response in milk yield to increase in body fatness at parturition is therefore strongly dependent on the relative levels of body fatness and metabolizable energy intake. The value of any improvement in condition of the ewe at parturition may be considerable when metabolizable energy intake during lactation is low but much less when it is expected to be high.
A note on allometric relationships in large white × landrace pigs
Authors: Petherick J. Carol
Published: September 2010

Linear measurements of six body dimensions were taken of Large White × Landrace pigs in the live-weight range of 1 kg to 286 kg. Logarithmic regression lines were fitted to the live-weight and measurement data. It was found that the body dimensions could be expressed as a function of live weight and that these equations agreed well with the simple allometric equation L = kW1/3, where linear dimension, W= live weight and k= an appropriate coefficient. It is suggested that these equations may provide a method of estimating the static space occupied by a pig and thus provide a basis for the development of space allocation recommendations in pig housing. It is also suggested that these principles may be applicable to other livestock.
A note on the effect of early weaning of lambs on reproductive rate of autumn lambed karakul ewes
Authors: Sefidbakht N. , Makarechian M. , Ghorban K.
Published: September 2010

From among a group of ewes in which oestrus had been induced following progesterone and PMS treatment and which had been mated in the spring, those lambing in early October were used for this experiment. They were divided into three treatment groups: (1) reared their lambs for 24 hr, (2) reared lambs for 16 days and (3) reared lambs for 75 days.

For the ewes rearing single lambs only in groups 1, 2 and 3, 100% (8 of 8), 93% (13 of 14) and 65% (11 of 17) respectively exhibited oestrus between lambing time in autumn and early winter (P<0·05). The average interval to post-partum oestrus was 29, 37, 50 days for group 1, 2 and 3 respectively. Group 3 exhibited first oestrus later than group 1 (P<0·01). These data show that lactation even during the peak of sexual activity has some suppressing effect on both the percentage of ewes showing oestrus and on delaying the onset of oestrus exhibition.
Influence of muscle location on fatty acid composition of total intramuscular lipids in the pig
Authors: Catchpole Christine , Lawrie R. A.
Published: September 2010

The relative concentration of the fatty acid components of the total intramuscular lipids from six muscle locations of pigs at 1·5 to 54 months of age were assessed by gas liquid chromatography. Although the pattern was generally similar at each location, differences between locations in the concentrations of oleic and arachidonic acids in particular were noted.

Differences between animals in the relative concentration of fatty acids (other than linoleic) could not be accounted for by the pattern of dietary intake.
The influence of package size and density on the intake of dried grass wafers fed to lambs
Authors: Tetlow R. M. , Wilkins R. J.
Published: September 2010

Wafers made from dried ryegrass were fed to castrated male lambs in two experiments of 40 and 30 days' duration. In the first experiment, wafers of chopped feed were prepared which varied in unit density from 0·7 g/ml to 1·0 g/ml. In the second experiment, coarsely ground forage was passed through a ram press with a die of 5 cm diameter and the extruded material was then split into quarter and half wafers or left unsplit as whole wafers. Voluntary intake was measured throughout each experiment.

For the wafers with density of 1·0 g/ml the daily intake of organic matter was 75 g/kg LW0·75 as compared with 64 g/kg LW0·75 for the wafers with density of 0·7 g/ml but this difference was not significant. There was a significant (P < 0·05) interaction between wafer density and sub-period of the experiment. The daily intake of low-density wafers, expressed in g/kg LW0·75, increased throughout the experiment, whereas that of the higher density wafers did not change.

There was no overall effect of package size on organic matter intake, but the interaction between package size and sub-period of the experiment was significant (P · 0·001). The intake of the whole wafers was initially lower than that for the other treatments, but increased throughout the experiment, whereas the intake of the quarter and half wafers remained steady.
The cold tolerance of beef and dairy type calves in the first weeks of life
Authors: Webster A. J. F. , Gordon J. G. , McGregor R.
Published: September 2010

1. British Friesian (F) and Hereford × British Friesian (H × F) male calves were raised from about 3 days to 8 weeks of age at air temperatures of 5, 10 or 15°C. They were given a milk replacer diet supplying 950 kJ metabolizable energy/kg M0·75.24 h.

2. There was no effect of environmental temperature on weight gain in calves of either type.

3. Total heat loss measured in a direct calorimeter, increased by about 5 kJ/kg M0·75.24 h per °C fall in air temperature. It was the same whether calves were penned singly or in pairs. Heat loss from F calves was slightly, but not significantly, greater at all temperatures than from H × F calves.

4. The proportion of heat lost by evaporation (a measure of environmental warmth) increased with increasing air temperature and was greater for H × F than for F calves at 15°C.

5. Tissue insulation and external insulation values were similar for H × F and F calves. The calculated lower critical temperatures of the F and H × F calves were 10 and 8°C respectively.

6. The results are discussed in relation to the housing requirements of young calves.