bluuebunny/crossref_metadata_2025 huggingface dataset:
Milk progesterone profiles during anoestrus through to pregnancy in Greek dairy goats (Capra prisca): the effect of melatonin treatment and male introduction
Authors: Belibasaki S. , Zygoyiannis D. , Davies P. , Doney J. M.
Published: September 2010

Two groups of 10 lactating does were housed separately, in isolation from bucks. Does in one group (T) were implanted with melatonin; the second group (U) were not implanted. After 30 days, five implanted and five non-implanted bucks were introduced, singly, into both groups of females each day. Subsamples of milk were taken from the daily output of each doe on 3 days each week for progesterone analysis.

Mean milk progesterone concentration during anoestrus varied significantly amongst individuals (P < 0·001), but the difference between T and U groups was not significant (1·51 and 1·93 (s.e.d. 0·52) μg/l, respectively). Elevated progesterone levels, indicative of a short oestrous cycle and commencing days 2 to 5 after male exposure, were observed in most does. Mean progesterone concentrations were 9·9 and 9·6 (s.e.d. 1·32) μg/l in T and U does respectively. Most does showed a second short cycle starting at 12 to 18 days, (mean concentration 8·4 and 10·6 (s.e.d. 1·64) ng/l, respectively). Untreated does then returned to anoestrus until mated at 63·1 (s.e. 0·94) days after male introduction. In contrast, T does either became pregnant or had a normal oestrous cycle, followed by a repeat cycle or pregnancy (mean onset 21·7 (s.e. 2·22) days after male introduction). The mean time of effective mating for group T does was 37·3 (s.e. 5·91) days, 26 days earlier than for U does (P < 0·001). Mean progesterone concentration in early pregnancy was 65·7 (s.e. 5·78) and 67·6 (s.e. 5·41) μg/l in T and U does, respectively. Males did not become sexually active until after the onset of luteal activity in the females, although treated males were earlier than untreated. There were no significant differences in lactation pattern associated with the progesterone profiles in the two groups.

The introduction of males during late anoestrus initiates short luteal cycles. Only those does closest to onset of the breeding season, in this case induced by melatonin, continue to cycle normally and mating success may require early stimulation of sexual activity in males.
The bioavailability of magnesium from different types of calcined magnesites of Greek origin
Authors: Zervas G. , Papadopoulos G.
Published: September 2010

The objective of this work was to determine the apparent bioavailability of magnesium from four different types of calcined magnesites of Greek origin. These four types (A, B, C, D) were different in particle size fractions and production process. The solubility of the above four magnesium samples and their fractions were determined: (a) in the laboratory using ammonium nitrate solution after 24-h shaking and (b) in vivo using a nylon bag technique after 24-h incubation.

Solubility was correlated with apparent bioavailability as determined in a balance experiment with five wether sheep in a 5×5 Latin-square design.

Sheep were kept in metabolism cages and were given daily a basal diet (500 g hay + 700 g concentrate) plus 2 g magnesium supplements from types A to D. The magnesium bioavailability of the basal diet was used as a base for the determination of the bioavailability of magnesium in A, B, C and D supplements.

Magnesium apparent bioavailability of the basal diet was found to be 0·203 and, for the supplements A, B, C and D, 0·381, 0·339, 0·315 and 0·292 respectively. The solubility of supplements A, B, C and D in ammonium nitrate solution and in vivo (using the nylon-bag technique) was found to be 0·812, 0·805, 0·784 and 0·773 or 0·294, 0·152, 0·102 and 0·200 respectively.

The solubilities of the magnesium supplements in ammonium nitrate solution and in vivo both reflected dietary bioavailability differences up to a point, but neither was well enough correlated with the apparent bioavailability as determined by the balance experiment, this being judged to be the most precise method for bioavailability determination.
Freezing buck semen diluted in amine-organic buffers
Authors: Dunner S.
Published: September 2010

Amine-organic buffers (BESKOH and TESTRIS) were compared for their ability to be used for buck semen dilution in a freezing procedure. BESKOH showed better results (P< 0·05) at the time of dilution and after chilling at +5°C (72% motilityv.54% at dilution and 62%v.39% after chilling). After freezing and thawing, none of the variables measured (motility, normal acrosome ridge and normal swelling) was significantly different. A washing procedure was necessary when freezing was undertaken and egg yolk addition was necessary to avoid cold shock as the temperature lowered during chilling. There were no significant differences between a 3% and 12% level of egg yolk addition.
Factors influencing the welfare and carcass and meat quality of pigs: the use of water sprays in lairage
Authors: Weeding C. M. , Guise H. J. , Penny R. H. C.
Published: September 2010

Two experiments were made to study the effects of a mist or large-droplet water spray for different lengths of time, on pig behaviour in lairage prior to slaughter and on subsequent carcass Quality. Water spraying caused more pigs to stand, chew the pen walls and root around the pen floor compared with unsprayed controls, and they also tended to fight more. The sprayed pigs produced meat of superior quality in terms of m. longissimus dorsi rate of acidification and colour. It is suggested that these benefits were due to the effects of evaporative cooling and increased water intake.
Effect of remating interval and diet on the performance of female rabbits and their litters
Authors: Cervera C. , Fernandez-Carmona J. , Viudes P. , Blas E.
Published: September 2010

In an experiment of factorial design, female rabbits were given four diets, containing 13·0, 11·4, 10·4 and 9·7 kJ digestible energy (DE) per g and subjected to two remating intervals (R) of 1 to 2 days (intensive) or 9 days (semi-intensive) from parturition. The experiment lasted for 2 years during which 352 does produced a total of 1254 litters. The only major differences due to diet were that the diet with the highest energy concentration, and which contained 35 g/kg added fat, promoted a significantly higher energy intake in lactation (111 v. an average of 94 MJ DE) than the other diets, and thereby increased litter weight at weaning at 28 days (3·48 v. 2·99 kg). Diet and R showed no major interactive effects. The intensive treatment significantly reduced parturition interval (46 v. 52 days) and increased the output of weaned rabbits per doe per year (35 v. 29). As actual R was more variable than the theoretical R imposed by the treatments, further analyses were made by dividing the does into four groups according to the actual R. In these analyses, the effects of R on current and subsequent lactation performance were assessed separately. The main difference between the groups was that litter size increased significantly with R (e.g. litter size at birth in subsequent parities was 8·0, 9·2, 9·7 and 9·0 for mean intervals of 2, 10, 16 and 37 days). However, the same pattern of differences occurred in the current parity, indicating that it was litter size that affected R, rather than the reverse (i.e. does with small litters conceived earlier than those with larger litters).
A note on change in body condition in Rasa Aragonesa ewes given ammonia-treated barley straw after weaning
Authors: Purroy A. , Jaime C. , Muñoz F. , Treacher T. T.
Published: September 2010

The effect of level of barley feeding (200, 400 or 600 g fresh matter per ewe per day) on the change in body condition, between weaning and mating, of ewes offered barley straw treated with ammonia was examined in experiment 1. In experiment 2, a 2 × 2 factorial design was used with two levels of restriction of metabolizable energy in lactation (proportionately 0·85 and 0·70 of the requirements) followed by two levels of feeding of barley (250 or 500 g) in the main experimental period. In experiment 1 the intake of straw was significantly lower when 600 glday was offered, and ewes given 200 g/day barky had significantly lower gain in live weight and body condition score. In experiment 2 the level of energy intake in lactation did not affect the intakes of straw, but the current level of barley feeding did.
A note on the effect of dietary variety on food intake of cattle
Authors: Ramos A. , Tennessen T.
Published: September 2010

The possibility of using dietary variety to enhance food intake of ruminants was investigated with 36 Hereford steers. For 21 days, 18 animals were given a monotonous diet of either hay or silage, while 18 others were given a varied diet of hay and silage offered in succession, at either 12- or 24-h intervals. Dietary variety did not affect total food intake (P > 0·05). However, when offered both foods at the end of the trial, animals which had been restricted to hay showed a proportional increase of 0·15 in their acceptance of silage (P < 0·05), whereas animals restricted to silage showed an increase of 0·49 in their acceptance of hay (P < 0·05)
Calculation of response and variance reduction due to multi-stage and multiple trait selection
Authors: Andersen S.
Published: September 2010

In deterministic comparisons of breeding schemes it is necessary to take account of variance reduction due to selection. This can take place as multi-stage selection within generations and it takes place across generations when offspring of selected parents are selected. A standard way to deal with this is to set up selection index equations where the parameters are altered as a consequence of selection. It is shown that if the breeding schemes use a univariate or multivariate best linear unbiased prediction (BLUP) animal model for prediction of breeding values this procedure can be simplified. This is done by modelling the distribution of estimated breeding value (EBV) utilizing that changes in EBV of an individual are independent of selection. In the univariate case the variance reduction and the resulting genetic gain can be calculated from the selection intensities and the accuracies in the unselected population. An expression is given for the response in each generation when selection is started in a base population with complete pedigree. This shows that a limiting value is obtained within three to four generations. The asymptotic response for several traits is described in the case where selection is on multitrait BLUP.
Effect of level of barley supplementation on the performance of continental × Holstein Friesian bulls given grass silage
Authors: Grundy H. F. , Hardy R. , Davies M. H.
Published: September 2010

Forty Charolais and 40 Limousin × Holstein Friesian bulls, 8 months old and weighing 315 kg live weight at the start of the experiment, were given grass silage to appetite throughout.

From 315 to 425 kg live weight they received: no supplement (S0), 1 kg (S1), 2 kg (S2) or 4 kg (S4) of a rolled barley supplement per head per day. After a mean treatment live weight of 425 kg had been achieved for each breed, the daily supplement of all treatments was changed to 3 kg of rolled barley per head per day until individual animals were adjudged to have attained a European Community (EC) external fatness score of 3 to 4L, at which point they were slaughtered.

Daily growth rates from 315 to 425 kg live weight were 0·67, 0·82, 0·94 and 1·25 (s.e.d. 0·042) kg for treatments S0, S1, S2 and S4 respectively. Following the change of supplement rate at 425 kg live weight, daily gains were 1·46, 1·36, 1·27 and 1·16 (s.e.d. 0·051) kg/day, giving overall gains of 0·99, 1·05, 1·08 and 1·19 (s.e.d. 0·033) kg/day respectively. The numbers of days taken to achieve slaughter condition from the start of the trial at 315 kg were 277, 251, 243 and 207 (s.e.d. 5·3) days respectively. Bulls were slaughtered at 17·0, 16·2, 15·9 and 14·7 months of age and produced carcass weights of 330, 324, 322 and 305 (s.e.d. 6·5) kg respectively.

Silage dry-matter intakes were 5·9, 5·1, 4·8 and 4·2 kg/day during the initial phase when differential supplement levels were being given and 7·0, 6·8, 6·2 and 5·8 respectively during the finishing period when all groups were being given 3 kg barley supplement daily. Food conversion ratios (kg dry matter intake per kg gain) were 9·1, 7·3, 6·9 and 5·8 during the initial phase and 6·4, 6·9, 6·9 and 7·2 respectively after 425 kg live weight.

It is concluded that barley supplements of 0 to 2 kg/day offered with high-quality grass silage during the growing stage (8 to 12 months of age), followed by at least 3 kg/day will produce finished bulls at an average of 325 kg carcass weight at 16 to 17 months of age. A higher level of 4 kg barley during the growing stage will reduce the slaughter period to approximately 15 months of age but carcass weight will also be reduced. Further studies are required to define the precise level of barley supplement during this earlier period.
The effects of forage type (maize-lablab or oat-vetch) and level of supplementation (wheat-middlings) on food intake, diet apparent digestibility, purine excretion and milk production of crossbred (Bostaurus × Bos indicus) cows
Authors: Khalili H. , Osuji P. O. , Umunna N. , Crosse S.
Published: September 2010

An experiment was carried out to evaluate the effects of forage type and level of concentrate supplementation on forage intake, diet apparent digestibility, purine excretion and milk production. Twelve crossbred cows (Bos taurus × Bos indicus), in early lactation, were allocated to the following six dietary treatments: maize-lablab forage (ML) or oat-vetch forage (OV), offered ad libitum, and supplemented with either 0, 2·5 or 5·0 kg per cow per day of a supplement (wheat middlings). A four-period, partially balanced, change-over design was used and the treatments were arranged as 2 × 3 factorial.

Mean organic matter (OM) intake was 670 g higher with cows on ML-based diets compared with those on OV-based diets (P<0·02). The apparent digestibilities of crude protein (CP) and neutral detergent fibre (NDF) were similar for cows given ML- or OV-based diets but the apparent digestibility of OM was higher for ML diets (P<0·05). Values of the degradation parameters (a, b and c) of DM and NDF were greater for ML forage than for the OV forage. Forage type did not affect daily milk yield nor excretion of purine derivatives in urine used to estimate microbial-nitrogen supply (P >0·05). The concentration of milk fat and total solids in the milk were similar for the two forage types offered but the concentration of milk protein was slightly higher for the cows given ML-based diets (P<0·05).

Daily OM intake increased by 3·75 and 2·70 kg per cow per day (P<0·001) respectively, when the amount of concentrate increased from 0 to 5·0 kg per cow per day for the ML- and OV-based diets. The CP apparent digestibilities of the diets were higher when the diets were supplemented with concentrates but there was no effect of supplementation on the apparent digestibilities of OM and NDF. The supply of microbial-nitrogen increased linearly with increasing level of concentrate supplementation (P<0·05). Milk yield increased linearly when the level of concentrate supplement increased from 0 to 5 kg (P<0·001), resulting in 0·39 and 0·29 kg more milk per day per kg additional concentrate given in cows on ML and OV, respectively. There was also a tendency for a quadratic effect (P<0·12), especially with ML diets, showing that when the level of concentrate increased from 0 to 2·5 or from 2·5 to 5·0 kg/day, the milk yield increased respectively by 0·62 and 0·15 kg/day per kg additional concentrate given.
Effect of breed type, sex and method of rearing on lifetime performance and carcass composition in a 20-month beef system: effects of winter feeding treatments
Authors: Lowman B. G. , Hunter E. A. , Hinks C. E. , Lewis M.
Published: September 2010

In the winter feeding phase of a lifetime study of spring-born cattle managed in a 20-month beef system, a total of four feeding treatments were imposed by increasing the level of concentrate supplement offered with ad libitum grass silage. The objective was to achieve a difference in live weight at the end of the winter of about 25 kg between food treatments. A multifactorial design was used with three animal factors — maturity (early maturing Hereford crosses v. late maturing Charolais crosses), sex (heifer v. steer) and method of rearing (suckled calves v. bucket-reared calves).

There were no significant differences between breeds but highly significant (P < 0·001) differences for method of rearing and sex. As a consequence live-weight differences at the end of the winter between breed types (18 kg) were less than the difference between the sexes (23 kg) and for method of rearing (25 kg) although all were highly significant. Although suckled animals had significantly lower growth rates they were still significantly fatter at the end of the winter as were heifers and Hereford crosses. Differences in dry-matter intake were reflected in growth rate.

Plane of winter nutrition had a highly significant effect (P < 0·001) on live weight and condition score at the end of the winter resulting in increments of about 23 kg and 0·12 units of condition for each level of feeding.

Interactions between the main production variables were not significant with the exception of feeding level and method of rearing. Suckled animals showed a significant (Y < 0·001) reduction in winter gain (proportionately 0·85 for that of bucket-reared animals) when offered the same diet. This reduction ranged proportionately between 0·25 and 0·08 for the lowest and highest daily levels of concentrate supplementation respectively. An extra 1 kg concentrates per day was required for suckled animals to achieve similar live-weight gains to bucket-reared animals.
The effect of immunoneutralization of PMSG near a gonadotropin-induced oestrus on the reproductive performance of gilts
Authors: Kirkwood R. N. , Peacock A. J. , Van Lunen T. A. , Thacker P. A.
Published: September 2010

In four experiments, 189 gilts either received PMSG antiserum around the time of a PMSG- (experiments 1, 2 and 3) or PMSG/hCG-induced (experiment 4) oestrus or served as controls. Ovulation rates were not affected by treatment. There was no treatment effect on pregnancy rate (experiments 2, 3 and 4). In experiment 2, numbers of embryos in PMSG-treated control gilts were quite low and were higher (P < 0·05) in those gilts subsequently receiving anti-PMSG treatment. In experiment 3, the mean number of embryos in control gilts were higher than in experiment 2 and there was no effect of immunoneutralization of PMSG. No treatment effect was evident in PMSG/hCG treated gilts (experiment 4). These data indicate that the immunoneutralization of PMSG is unlikely to improve the reproductive performance of gilts following a gonadotropin-induced oestrus except in gilts that otherwise would have poor performance.
Effect of chemical structure of fats upon their apparent digestible energy value when given to young pigs
Authors: Powles J. , Wiseman J. , Cole D. J. A. , Hardy B.
Published: September 2010

The effect of degree of saturation (ratio of unsaturated to saturated fatty acids, U/S) and free fatty acid (FFA) content of fats upon their digestible energy (DE) values was investigated in post-weaning pigs. The two fats evaluated were soya-bean oil (SO) and tallow (T) (representing extremes of saturation) together with their acid oils (SAO and TAO respectively) providing high FFA levels). Blends of the four fats provided treatments with varying FFA content and U/S ratios. The experimental fats were evaluated by substitution, at 40, 80 and 120 g/kg into a basal diet, in a randomized-block design, with 98 gilts and 98 boars of approximately 12 kg live weight. Pigs had been weaned at 28 days of age and experimental diets were given 7 days after weaning. When pigs obtained a weight of 10 kg the inert marker titanium dioxide was added to the diets as a reference substance. A 5-day adjustment period was allowed followed by a 5-day collection period of faeces by grab sampling. 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 demonstrated effects of fats, rates of inclusion, and fats × rates (P < 0·001 in all cases). There was no effect of sex. 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 fat apparent digestibility of fats and their respective gross energies gave DE values for fats which were: SO = 37·2 MJ/kg, SAO = 35·0 MJ/kg, T = 34·3 MJ/kg and TAO = 27·4 MJ/kg. Data for fat blends intermediary between these fats showed that DE improved as a function of U/S and that DE declined linearly with increasing FFA content.
Selection for components of efficient lean growth rate in pigs 1. Selection pressure applied and direct responses in a Large White herd
Authors: Cameron N. D.
Published: September 2010

Responses to four generations of divergent selection for lean groivth rate with ad-libitum feeding (LGA), for lean food conversion (LFC) and for daily food intake (DFI) in Large White pigs were studied. The LGA (LFC) selection criterion was designed to obtain equal correlated responses in growth rate (food conversion ratio) and carcass lean content, measured in phenotypic s.d. The selection criteria had phenotypic s.d. of 27, 29 and 253 units, respectively, and results are presented in s.d. units. There was a total of 3537 pigs, with an average of 40 boars and 40 gilts performance tested in each of the high, low and control lines per generation and the lines consisted of 10 sires and 20 dams. The generation interval was equal to 13·5 months. Animals were performance tested in individual pens with mean starting and finishing weights of 30 kg and 85 kg respectively.

Cumulative selection differentials in the three selection groups were 5·8, 3·6 and 3·3 phenotypic s.d. for LGA, LFC and DFI respectively. Direct responses to divergent selection were 1·7, 1·3 and 1·2 (s.e. 0·17) for LGA, LFC and DFI. The correlated response in LFC (1·6 (s.e. 0·18)) with selection on LGA was greater than the direct response in LFC. Conversely, the direct response in LGA was greater than the correlated response (1·1 (s.e. 0·18)) with selection on LFC. The response in LFC (–1·1 (s.e. 0·17)) with selection on DFI was similar in size but opposite in sign to the direct response in LFC. Responses were asymmetric about the control, as the high LGA and LFC responses were proportionately smaller (0·74 and 0·58) than low line responses. In contrast, the difference between the high DFI and control was four times greater than the difference between low line and control.

Heritabilities of LGA, LFC and DFI were 0·38, 0·35 and 0·29 (s.e. 0·03), when estimated by residual maximum likelihood, with common environmental effects of 0·09 (s.e. 0·02). Genetic correlations for LGA with LFC and DFI were positive, 0·76 (s.e. 0·03) and 0·23 (s.e. 0·07), but the genetic correlation between DFI and LFC was negative, –0·45 (s.e. 0·06). The experiment demonstrated that substantial responses to selection can be achieved in LGA, LFC and DFI. Selection on LGA resulted in larger direct and correlated responses than selection on LFC.
A note on consequences of single-trait selection for insulin-like growth factor 1 (IGF-1) in beef heifers
Authors: Davis M. E. , Bishop M. D.
Published: September 2010

Eight sets of identical twin heifers and their first three calf crops were used to determine effects of single-trait selection for blood serum insulin-like growth factor 1 (IGF-1). Twin heifers were offspring of Simmental sires and Hereford × Simmental or Hereford × Angus dams. All 16 heifers were mated with the same Simmental bull in each year of the study to produce calves born in 1989, 1990 and 1991 (no. = 16, 13 and 10, respectively). Although differences were noted in performance of progeny from the four twins with the highestv.the four with the lowest IGF-1 concentrations, they zoere not large enough to recommend single-trait selection for blood serum IGF-1 in beef heifers.
Effects of avoparcin and bovine somatotropin on measures of production and reproduction in dairy cows
Authors: Murphy M. G. , O'Callaghan D. , Rath M. , Austin F. H. , Roche J. F.
Published: September 2010

The objective was to determine the effects of avoparcin, bovine somatotropin (bST) and the additive effects of both avoparcin and bST on milk yield, milk composition, live-weight changes and reproduction parameters in post-partum dairy cows. Forty-eight autumn calving cows were allocated using a split-plot within randomized complete-block design to the following treatments: (i) control (2 ml saline plus 1 kg untreated concentrate per day); (ii) avoparcin (2 ml saline plus 1 kg concentrate containing 100 mg avoparin per day); (Hi) bST (25 mg bST in 2 ml saline plus 1 kg untreated concentrate per day); and (iv) avoparcin plus bST (25 mg bST in 2 ml saline plus 1 kg concentrate containing 100 mg avoparcin per day). All injections were given subcutaneously and treatment continued for 84 days beginning 55 (s.e. 4) days after calving. The cows were offered grass silage ad libitum supplemented with 7·2 kg cereal-based concentrates daily. Milk yield and milk composition were measured thrice and once weekly, respectively. The cows were weighed and body condition score was assessed every 2 weeks.

Mean daily milk yield of cows assigned to control was 20·1 (s.e. 1·5) kg, avoparcin, 21·5 (s.e. 1·5) kg, bST, 23·9 (s.e. 1·0) kg and avoparcin plus bST, 25·2 (s.e. 1·2) kg over the 84 days of the trial. bST increased milk yield proportionately by 0·18 compared with all cows not given bST (P < 0·01). Avoparcin did not significantly increase milk yield. There was no effect of any treatment on milk composition, body weight or body condition score. None of the experimental treatments had any effect on calving to first service interval, calving to conception interval, number of services per conception or overall conception rate.

These results show that in early lactation, avoparcin alone had no effect on production or reproduction parameters in dairy cows; bST alone increased milk yield but did not affect any other production or reproduction parameter. There was no significant additional increase in milk yield when avoparcin and bST were given in combination, compared with bST alone.
Combining the genetic and clonal responses in a closed dairy cattle nucleus scheme
Authors: de Boer I. J. M. , Meuwissen T. H. E. , van Arendonk J. A. M.
Published: September 2010

Designs testing clones in a closed nucleus, in which 1024 cows are tested each year, were compared for their additive genetic response to selection (genetic response) and their genetic superiority of female genotype(s) selected for commercial cloning (clonal response), using stochastic simulation. Clones were tested at the expense of dam or sire families, matings per dam (sire), or full-sibs per family. The reference design maximized the genetic response corrected for inbreeding in the absence of cloning. The trait considered was overall economic merit for milk production, which was simulated assuming an approximate infinitesimal model with both additive and dominant gene action. Bulls and cows eligible for breeding were selected on their animal model estimated additive genetic effect at either 15 or 27 months of age. Female genotypes eligible for commercial cloning were selected on their estimated total genetic effect at 27 months of age. All (fe)male full-sibs were available for selection. With only additive gene action, testing clones at the expense of sire families, matings per dam or full-sibs per family reduced genetic response, while it increased clonal response and inbreeding. Testing clones at the expense of dam families, however, added to both the genetic and clonal response without increasing inbreeding. When eight clones were tested at the expense of dam families, the genetic response and the final genetic level of commercially available cloned embryos were maximal. Accuracy of clonal selection equalled 0·83. With dominant gene action, however, testing two clones at the expense of dam families maximized the final genetic level of cloned embryos, irrespective of the level of inbreeding depression (accuracy of 0·72). Reliable commercial clone lines can be produced now and in future generations by testing clones at the expense of dam families.
Maximizing genetic response in crossbreds using both purebred and crossbred information
Authors: Wei Ming , van der Werf J. H. J.
Published: September 2010

A combined crossbred and purebred selection (CCPS) method, i.e. using crossbred and purebred information, was proposed to achieve genetic response in crossbred animals. Selection index theory was applied to establish a CCPS index. The CCPS was compared with pure-line selection (PLS) and crossbred selection (CS) methods. The genetic correlation between purebred and crossbred performance (rpc) and crossbred heritability (hc2) are crucial factors in the comparison. The CCPS is always better than PLS or CS when a fixed number of purebred progeny is tested. With a fixed total number of purebred and crossbred tested progeny, CCPS is only worse than PLS for very high values of rpc (>0·8). Superiority of CCPS over PLS increases and over CS decreases with decreasing rpc. The larger hc2is, relative to purebred heritability (hc2the more response CS and CCPS will achieve. The robustness of CCPS against inappropriate assumptions on rpcand hc2values was investigated. The expected response is always an overestimate, and the actual response is smaller than the optimal response when rpcis assumed one but the true rpcis smaller. The difference between actual and optimal response increases as rpcdecreases but it is small for large rpcvalues (e.g. <3% for rpc>0·7). The expected response is smaller than the actual response when rpcis large and hc2> hp2Finally, the actual response to CCPS is larger than the optimal response to PLS for positive values for rpc. The main conclusions are: (1) CCPS method is optimal for obtaining genetic response in crossbreds; and (2) CCPS with inappropriate assumptions on rpcand hc2values (e.g. recognizing crossbreds as purebreds) achieves more genetic response than PLS for common values of rpcand crossbred heritability.
The use of sheep as a model to predict the relative intakes of silages by dairy cattle
Authors: Cushnahan A. , Gordon F. J. , Ferris C. P. W. , Chestnutt D. M. B. , Mayne C. S.
Published: September 2010

A study was carried out to determine if sheep could be used as a model for predicting the intakes of silages by cattle. Fifty ewes and 45 cows were offered five grass silages unsupplemented in two parallel randomized-block experiments over a 4-week period. Each silage had been made using the same equipment over a range of cutting dates (May, July, August 1991). The silages differed in fermentation characteristics, with lactic acid concentrations varying from 15·3 to 90·7 g/kg dry matter, and ammonia-nitrogen concentrations from 77 to 198 g/kg nitrogen. When expressed on a metabolic live-weight basis, the mean intakes of silages by cows were 2·25 times those of the sheep, with the mean intakes being 35·1 and 79·1 g/kg M0·75 for the sheep and cows respectively. However, there was no significant correlation between recorded intakes during the 4th week of the study by the two species (y (cows) = 0·62× (sheep) + 58·40; r2 = 0·03). It was concluded that sheep were not a useful model system to predict the intakes of a range of grass silages of similar chop length by dairy cows.
A note on direct measurement of food spillage when growing pigs are given food to appetite
Authors: Morrow A. T. S. , Walker N.
Published: September 2010

Ten crossbred boars were penned individually and offered either meal or pellets of identical composition to appetite from single space hopper feeders which also provided water. The hoppers were sited on raised steel mesh platforms 1·2 m × 0·87 m in size under which was placed a similar sized collecting tray. Spilled food was collected for 24 h once weekly for the 4-week experimental period. Live-weight gain tended to be lower on the meal diet compared with the pellets (882 v. 968 (s.e. 28·7); P = 0·07) while food conversion efficiency (g food per g growth) was worse on the meal diet (2·65 v. 241 (s.e. 0·059); P < 0·05). Food spillage is the most likely explanation for the difference in food conversion, however collectable spilled food was (g/g food offered) 0·0089 and 0·0026 respectively of meal and pellets offered. The value for the meal diet is about one-tenth of the expected value and suggests that direct collection of spillage from non-pelleted diets even over a wide area in front of the feeder is not an accurate technique.
A note on using biased parameter values and non-random mating to reduce rates of inbreeding in selection programmes
Authors: Grundy B. , Caballero A. , Santiago E. , Hill W. G.
Published: September 2010

The value of a parameter such as heritability (h2) or intra-dass correlation in best linear unbiased prediction (BLUP) with the animal model or a family selection index affects both the rate of response achieved and the rate of inbreeding. If in BLUP an estimate of h2 is used which is biased upwards above its actual value, the rate of inbreeding can be substantially reduced with little reduction in the rate of response. Further, by mating individuals from families in which many are selected to others from families with few selected (compensatory mating), rates of inbreeding can be further reduced without substantial effect on response.
Effect of animal size on the response in the performance of beef cattle to an improvement in silage quality
Authors: Steen R. W. J. , McIlmoyle W. A.
Published: September 2010

Two experiments have been carried out to examine the interaction between animal size and the response in animal performance to an increase in the digestibility of grass silage. In experiment 1, grass silages harvested during July and August after regrowth intervals of 43 and 85 days were offered ad libitum both unsupplemented and supplemented with 2 kg of concentrates per head per day to British Friesian steers of (±s.e.) 170±1·9, 300±2·9 and 420±3·6 kg initial live weight. Earlier cutting did not affect silage dry-matter intake or live-weight gain but increased carcass gain by 0·12kg/day (P<0·01).

In experiment 2, early-cut grass silage, made from two regrowths of perennial ryegrass, which were harvested during July and August after regrowth intervals of 43 and 48 days, and late-cut silage, made from a single regrowth, which was harvested in August after a regrowth interval of 90 days, were offered ad libitum to 84 Hereford-cross steers of (±s.e.) 170±3·4, 300±4·4 and 420±5|·2kg initial live weight. Earlier cutting increased silage dry-matter intake by 340 g/kg, live-weight gain by 0·23 kg/day and carcass gain by 0·18 kg/day (P<0·001). It i s concluded that increasing the digestibility of grass silage by cutting grass at an earlier stage of growth is likely to produce a substantial increase in the daily carcass gain of beef cattle and that the response to higher digestibility is as great with mature cattle as with young, growing animals.
A note on the effect of limestone supplementation on the performance of cattle given barley-based diets
Authors: Bass Jean M. , Fishwick G. , Parkins J. J.
Published: September 2010

Groups of Hereford-cross steers weighing 283 kg were given 0·6 kg dry matter hay per head per day, and bruised barley supplemented with 40 g of a fully soluble liquid product per kg, containing urea, minerals and vitamins,ad libitum. Half the animals received 10 g limestone per kg diet as an additional supplement. Over a 105-day period the food intake of the limestone-supplemented animals was 0·20 higher than that of unsupplemented animals. The resultant daily live-weight gain was 1·22 kg compared with 0·92 kg for the animals receiving the diet containing no additional limestone. Food conversion ratios (kg/kg live-weight gain) were improved by limestone supplementation from 6·84 to 6·19. Limestone inclusion did not appear to influence the low concentrations of starch (ca. 15 g/kg) present in the faecal dry matter but there was a small significant difference in faecal pH.
Comparative performance and body composition of control and selection line large white pigs 2. Feeding to appetite for a fixed time
Authors: Ellis M. , Smith W. C. , Henderson Ruth , Whittemore C. T. , Laird R.
Published: September 2010

Food intake was individually measured for Large White control (C) and 10th generation index-selected (S) pigs fed twice daily to appetite on a fixed time trial. Thirty-nine C and 38 S boars were slaughtered, their carcasses dissected and whole empty bodies minced and chemically analysed after an 84-day trial starting at 28·6 ± 0·30 kg live weight. S boars ate proportionately 0·08 less than C boars in the first 42 days of the trial (79 v. 86 kg, P < 0·01), but S and C boars ate similar amounts (114 v. 117 kg, NS) in the last 42 days. S boars grew 0-04 faster than C boars (918 v. 886 g per day, NS), and had 0·09 better food conversion efficiency (0·404 v. 0·369 gain per kg food, P < 0·001). S boars contained more water than C boars (53·5 v. 48·9 kg, P < 0·001), more protein (15-4 v. 14-2 kg, P < 0·01), less lipid (20·8 v. 25·1 kg, P < 0·001), less gross energy (1 199 v. 1 357 MJ, P < 0·01) but a similar amount of ash. S carcasses had 3 kg more lean (36·5 v. 33·5 kg, P < 0·001) and more bone than C carcasses (7·14 v. 6·71 kg, P < 0·05), but contained 3 kg less total fat (19·6 v. 22·6 kg, P < 0·01). The lean tissue growth rate of S boars was 327 g per day which was 31 g per day faster than for C boars (P < 0·001). Appetite reduction in S boars enhanced fatness differences between the lines.
The influence of nutrition in early life on growth and development of the pig 1. Effects of protein nutrition prior and subsequent to 6·5 kg on growth and development to 45 kg
Authors: Campbell R. G. , Dunkin A. C.
Published: September 2010

Forty-five piglets were used to study the effects of feeding diets containing 153, 239 or 321 g crude protein per kg dry matter between 1·8 and 6·5 kg live weight, and low and high protein diets subsequent to 6·5 kg live weight on growth performance, body composition and the cellularity of skeletal muscle to 45 kg live weight.

Reducing dietary crude protein between 1·8 and 6·5 kg live weight depressed growth performance and at 6·5 kg live weight increased body fat content but reduced body protein, body water and the weight and DNA content of the adductor muscle. The effects of dietary protein content before 6·5 kg live weight on body composition at the latter weight were still evident in pigs killed at 11·5 kg live weight whilst the differences in muscle DNA persisted to 45 kg live weight.

On the lower protein treatment subsequent to 6·5 kg live weight there was a tendency for pigs given the lowest protein diet before 6-5 kg live weight to exhibit better growth performance and deposit protein at a faster rate than those given the higher protein diets. However, these responses were reversed on the higher protein treatment subsequent to 6·5 kg live weight.

The effects of dietary protein content subsequent to 6·5 kg live weight on growth performance, body composition and the cellularity of muscle tissue were qualitatively the same as those for the live-weight phase 1·8 to 6·5 kg.
Dissemination of genetic improvement through a livestock industry
Authors: Bichard Maurice
Published: September 2010

A theoretical study is reported of the way in which additive genetic improvement, made in a nucleus population, is passed to successive levels in a three-tier multiplication system. The rate at which progress accumulates at each level is approximately equal. The extent to which each tier is genetically behind the previous one has been termed the ‘improvement lag’. These lags can be considerable; their actual size is determined by the annual rate of progress in the nucleus, the age structure in the lower tiers, and by the origins and degree of selection achieved in the animals used as parents in these tiers. Only improvements generated in the top tier are cumulative. The scope for reducing the improvement lag is discussed within the context of livestock production in Britain.
Selection of mice for growth on constant and on changing maize-milk diets
Authors: Bateman Nigel
Published: September 2010

Effects of constant and of changing diets on responses to selection were studied. Mice were fed maize meal and dried skim milk from 3 to 5 weeks of age and were selected for live-weight gains in that period. Gains in the generation prior to selection were 17·7 g on 76% maize (24% milk), 8·0 g on 16% maize and 5·5 g on 100% maize.

The Fixed optimum line was selected on 76% maize, the Milk line on 16% maize and the Maize line on 100% maize. The diets of three other lines were reviewed at each generation, and two diets were fed on each occasion. The diets of the Shifting optimum line straddled the optimum of the previous generation; those of the Milk-impelled line at first had a little more than the optimum amount of milk, but were made more milky as normal growth resumed; and the Maize-impelled line was similarly directed towards 100% maize. Back selected milk, optimum and maize sublines were taken off the three lines on constant diets. The Control line measured unimproved rates of growth on 16%, 52%, 76% and 100% maize.

Dietary effects were not always repeatable. Controls on the optimum diet, 76% maize, were the most stable across generations and with this diet, gains generally had the lowest phenotypic variance within generations —g2. With 100% maize, this variance was slightly larger—8 g2. The diet with the least stable effect was 16% maize; as Control gains rose from 8 to 15 g, phenotypic variance fell from 21 to 6 g2. On various diets between 88% and 96% maize, the variance of the Maize-impelled line rose from 6 to 34 g2without commensurate changes in its mean gain.

Responses of generally about 5 g above controls were made in five generations of selection. The Maize line was exceptional in making no forward response. Heritability of growth between forward and back selected sublines was highest on good diets (0·49 on 76% maize) and lower on poor diets (0·20 on 16% maize and 0·28 on 100% maize).

The Fixed and Shifting optimum lines do not as yet differ on comparable diets; nor the Milk and Milk-impelled lines on 16% maize. The Maize-impelled line has not yet been tested on 100% maize and cannot be compared with the Maize line. Family-by-diet interactions were smaller than consistent family differences. It is concluded that genotypic improvements may be effective over a wide range of maize-milk diets.
The growth of young cattle fed on dried grass alone and with barley 2. Effects on digestion
Authors: Poutiainen E. K. , Lonsdale C. R. , Outen G. E.
Published: September 2010

1. Young cattle were fed on four types of wafer containing chopped or coarsely-milled dried grass, with or without 50% of barley.

2. At slaughter, the alimentary tract of each animal was removed and the contents of each part were weighed and sampled to determine the extent and site of digestion. Chromic oxide was used as an indigestible marker.

3. The form in which the grass was processed had no effect on any of the parameters measured.

4. The dry-matter content of the digesta in all parts of the alimentary tract was significantly higher when barley was included in the wafers. The inclusion of barley decreased the proportion of acetic acid and increased the proportion of butyric acid in the rumen liquor. The proportions of propionic and valeric acids were unaffected. Barley also appeared to reduce the proportion of digestible dry matter which disappeared in the forestomachs (31·44%) compared with that when grass was given alone (42·59%).

5. With grass alone about 70% of the apparently digestible cellulose disappeared from the forestomachs, but the technique used did not allow a good estimation of these proportions when mixed diets were given. The retention time of dry matter in the forestomachs was not affected by the diet but the inclusion of barley in the wafers increased the retention time of cellulose in the forestomachs.

6. Of 1·6·1·9 kg of starch ingested in mixed diets, 92-96% was apparently digested in the forestomachs, and only 80-130 g per day escaped rumen fermentation. The intake of starch on diets of grass alone was negligible and almost all the soluble sugars were digested in the forestomachs.

7. More N was recovered at the omasum than was ingested, but the different diets had no effect on the site of digestion of N.
The distribution of chemical fat in the bodies of scottish blackface ewes
Authors: Russel A. J. F. , Doney J. M. , Gunn R. G.
Published: September 2010

The distribution of chemical fat throughout the major depots of the fleece-free empty body was studied in 30 mature Scottish Blackface ewes from two sources and covering a wide range of fatness.

Relationships between amounts of chemical fat in individual depots and total body fat are presented. These provide information regarding rates of change in the distribution of fat with changing fatness. Information is also presented which allows estimates of the distribution of chemical fat throughout the body to be made from subjectively assessed condition scores.
Nutrition of the early-weaned calf. XII. The effect of diets differing in physical form on feed intake and rate of gain
Authors: Kay M. , MacLeod N. A. , Andrews R. P.
Published: September 2010

1. Intake and digestibility were determined in a trial with 30 British Friesian calves given diets containing straw and either 3·2 (H), 2·9 (M) or 2·6 (L) Meal metabolizable energy per kg dry matter. For one series of diets the straw was chopped and the diets were made into cobs (1·0 × 2·5 × 4·0 cm); for a second series the straw was milled and the diets were made into pellets (1·0 × 1·25 cm)

2. Calves given the H diets containing either chopped or ground straw ate and gained less well than calves given M and L diets but there were no differences in feed intake or growth between calves given M and L diets.

3. The retention of feed residues was greater and the flow of fluid out of the rumen was less for cattle offered the H diet than the L diet.
Effect of early weaning on the performance of male buffalo and cattle calves
Authors: El-Naggar A. A. , El-Shazly K. , Ahmed I. A.
Published: September 2010

Forty-eight uncastrated buffalo male calves and 16 male Friesian × Egyptian Native calves were used in two experiments to study the effect of weaning age on the performance of calves fed on a high concentrate ration after the first four months of age. Half of the buffalo calves were weaned at 120 days of age on to 330 kg whole buffalo milk (late-weaned) and the other half were weaned at 45 days of age on to 100 kg whole buffalo milk (early-weaned). Cattle calves were weaned at 31 days of age on to 65 kg whole cow milk. At the age of 7 days the calves were put on a high energy ration of 74% total digestible nutrients and 13·5% digestible protein. After 125 days of age all calves were offered a high concentrate ration (cottonseed cake and rice bran in the ratio of 1:1, plus 2% Ca(OH)2 and 1% common salt). Air-dried roughage was supplied at a level of ½% of the body weight. Buffalo and f-Native calves reached a slaughter weight of 400 kg or more about 540 days of age. Three-quarters Friesian calves reached the same weight at 480 days of age. The high concentrate ration caused a high incidence of bloat in ¾Friesian bulls. The efficiency of feed utilization was better for cow calves than that for buffalo calves. The system of early weaning of buffalo calves proved to be most economical and saved about 26% of the cost per kg live-weight gain. Slaughter experiments indicated that fat deposition was greater in male cattle of 400 kg than in buffalo bulls.