bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling responses to selection for resistance to gastro-intestinal parasites in sheep
Authors: Bishop S. C. , Stear M. J. 
Published: September 2010

AbstractThis paper describes a general framework which enables responses to selection for resistance to gastro-intestinal parasites in sheep to be stochastically modelled. The model incorporates between-animal variation for pasture intake, the proportion of larvae ingested from the pasture which survive to become adults, the fecundity of the mature worm, along with density-dependent control of this trait and the mortality rate of the worms. The between-animal variation for each component is partitioned into genetic, permanent and temporary environmental components which vary with age. Infection rates are estimated from existing pasture larval contamination and new contamination from infected animals. Using this framework, selection for reduced mean faecal egg count was practised, in silico, for a period of 10 years. Several general patterns emerged. First, a curvilinear response to selection was observed, with responses initially being large then declining over time. Mean faecal egg count declined from approximately 500 to 140 eggs per gin 10 years and worm burdens and pasture larval contamination showed similar patterns of response. The initial responses to selection were approximately 1·7 times that predicted by quantitative genetic theory because the epidemiology of the disease changed as the animals' genetic resistance improved. A method of partitioning selection responses into components due to the altered genotypes of the animals and components due to altered disease epidemiology is outlined. Secondly, the faecal egg count distribution became more aggregated, or skewed, as selection progressed. Thirdly, correlating pasture contamination levels across years (carry-over effects) resulted in even greater apparent responses to selection. Finally, regular anihelmintic treatment reduced mean faecal egg counts but did not alter the patterns of response to selection, indicating that selective breeding should be feasible under a variety of anthelmintic regimes.
Effects of isolation on the behaviour, live-weight gain, adrenal capacity and immune responses of weaned red deer hind calves
Authors: Hanlon A. J. , Rhind S. M. , Reid H. W. , Burrells C. , Lawrence A. B. 
Published: September 2010

AbstractAt weaning at 3 months of age (week 1), 30 red deer hind calves were housed in six groups of five animals at a stocking density of 1·5 m2 per head and maintained in these groups for 4 weeks. At the start of week 5, all calves were immunized with ovalbumin (OVA). Fifteen calves, from three groups, selected at random, were transferred to individual pens which restricted visual and tactile contact with others (ISO) while the remaining animals were kept in their groups (GP). The behaviour, food intake, live-weight gain, antibody and lymphocyte responses in vitro to OVA and lymphocyte responses in vitro to the non-specific mitogen, concanavalin A (ConA), of all calves were assessed in each of weeks 5 to 9. Isolated calves had a lower mean live-weight gain than GP calves (P < 0·001), although there were no differences in food intake. Significantly more time was spent lying (P < 0·001) but less time feeding (P < 0·05) and self-grooming (P < 0·001) by ISO than by GP calves. There was no significant difference between ISO and GP calves in the cortisol response to an ACTH challenge test (10 i.u.) at week 11. Lymphocyte responses and antibody titres to OVA were lower in GP than in ISO calves at weeks 7 (P < 0·05) and 8 (P < 0·05), respectively. In contrast, GP calves had greater lymphocyte responses to the non-specific mitogen, ConA, in weeks 7 (P < 0·05) and 10 (P < 0·001) but not in week 9 compared with ISO calves. Differences in lymphocyte stimulation were attributed to the non-specific mitogenic nature of ConA. Factors such as agonistic interactions evident in group housing may have compromised the antibody and lymphocyte responses to OVA by GP calves but conversely the lack of social contact may have also suppressed behavioural activity in ISO calves.
Use of near infrared reflectance spectroscopy to predict and compare the composition of carcass samples from young steers
Authors: Sanderson R. , Lister S. J. , Dhanoa M. S. , Barnes R. J. , Thomas C. 
Published: September 2010

AbstractThe aim of the current study was to investigate the effects of level of feeding and level offish-meal supplementation on the carcass composition of young steers and in doing so, to assess the potential for employing near infrared reflectance spectroscopy (NIRS) in such studies. In addition to wet chemical techniques, NIRS was used to examine carcass samples from animals offered silage-based diets at one of four levels of feeding ranging from near maintenance toad libitumand with one of four levels offish meal (0, 50,100 or 150 g/kg silage dry matter).Wet chemical data indicated an increase in fat concentration (P < 0·001) and decrease in crude protein concentration (P < 0·05) in the fresh carcass in response to increasing level of feeding but no statistically significant effect of level of fish meal. Ash concentration was not affected significantly by either level of feeding or level of fish-meal supplementation. Ground, freeze-dried samples were scanned in the wavelength range 1100 to 2498 nm. Calibration equations for ash, fat and crude protein concentration (g/kg carcass) were derived using a modified partial least-squares regression technique. Equations were found to be superior for fat compared with those for crude protein and ash. Standard errors of calibration (g/kg carcass) and multiple correlation coefficients of 6·96 and 0·42, 6·61 and 0·95 and 4·36 and 0·61 were obtained for ash, fat and crude protein respectively with corresponding standard errors of cross validation of 7·71, 7·82 and 4·96 g/kg carcass respectively. Qualitative analysis of spectral information using multivariate techniques and difference spectra clearly showed differences in carcass composition resulting from the different levels of feeding and less so the different levels offish-meal supplementation.It is shown, that NIRS can be used both quantitatively and qualitatively to study the effects of nutrition on carcass composition.
Influence of lambing date on subsequent ovarian cyclicity and ovulation rate in ewes
Authors: Mitchell L. M. , King M. E. , Aitken R. P. , Wallace J. M. 
Published: September 2010

AbstractThe effect of lambing date on the subsequent onset and duration of ovarian cyclicity in Mule (Bluefaced Leicester × Scottish Blackface) ewes was investigated. Nineteen ewes which had lambed in January (16 January 1993 (s.e. 3 days)) and been weaned in February-March and 22 comparable ewes which had lambed in May (14 May 1993 (s.e. 2 days)) and been weaned on 23 August were maintained at pasture as two isolated groups. A raddled vasectomized ram was continually present with each group from 14 July 1993 to 26 May 1994 and marked (oestrous) ewes were recorded twice weekly. Ovarian activity was assessed by measuring peripheral progesterone concentrations in blood samples collected twice weekly and by laparoscopic viewing of the ovaries of all ewes during October, January and March. The onset and duration of ovarian activity were significantly affected by the previous lambing date. For January and May lambing ewes, mean dates of onset were 5 September 1993 (s.e. 2 days) v. 25 September 1993 (s.e. 4 days) (P < 0·001) and of cessation were 5 April 1994 (s.e. 5 days) v. 10 April 1994 (s.e. 3 days). Mean durations of ovarian activity were 212 (s.e. 6) and 195 (s.e. 5) days (P < 0·05) during which 12·4 (s.e. 0·29) and 11·5 (s.e. 0·38) ovarian cycles respectively were recorded. Ovulation rate was not affected by previous lambing date but was significantly lower in March compared with October (January lambing ewes 1·7 (s.e. 0·1) v. 2·3 (s.e. 0·1) (P < 0·001); May lambing ewes 1·6 (s.e. 0·1) v. 2·1 (s.e. 0·1) (P < 0·01)). Results demonstrate that (i) Mule ewes have a potential breeding season of up to 8 months duration; (ii) the onset and duration of ovarian activity can be influenced by previous lambing date; and (Hi) a seasonal decline in ovulation rate may, in practical terms, result in a lower lambing percentage for animals bred towards the end of their natural breeding period.
Selective enhancement of growth in twin foetuses by shearing ewes in early gestation
Authors: Morris S. T. , McCutcheon S. N. 
Published: September 2010

AbstractShearing ewes during pregnancy frequently increases the birth weight of lambs. In housed ewes, the birth weight responses are greatest when shearing occurs relatively early in pregnancy. This study examined the effects of the timing and method of shearing on foetal growth, as measured by birth weight, in ewes at pasture. Border Leicester × Romney ewes were allocated at day 50 of pregnancy to: four ‘time of shearing’ treatments — pregnancy day 70 (P70), P100, P130 (no. = 60 for each treatment) and unshorn (no. = 34); two methods of shearing (by standard comb or cover comb); and two levels of pregnancy/rearing rank All ewes had been mated over a 14-day period and grazed pasture together throughout the trial The mid-point of lambing was 17 August.At no time during pregnancy or lactation did ewe live weight differences between the groups exceed 4 kg. Ewes shorn by cover comb were heavier prior to lambing and during lactation than standard comb-shorn ewes. Time of shearing, method of shearing and ewe rearing rank had no effect on ewe annual greasy fleece production. There was a highly significant (P < 0·001) interaction between the effects of birth rank and time of shearing on lamb birth weight. Time of shearing did not affect birth weight of single-born lambs but birth weight of twin lambs increased with earlier maternal shearing to a maximum of 0·7 kg (per lamb) in those born to ewes shorn on P70. These results imply that shearing reduced the greater extent of maternal constraint which applies to the growth of twin v. single foetuses in utero. This selective increase in birth weights of twins achieved by early pregnancy shearing may have advantages in reducing lamb mortality.
Contribution of dietary nitrogen and purine bases to the duodenal digesta: comparison of duodenal and polyester-bag measurements
Authors: Pérez J. F. , Balcells J. , Guada J. A. , Castrillo C. 
Published: September 2010

AbstractFour ewes fitted with ruminal and duodenalT-piece cannulas were given fourdietsin a 4 × 4 factorial design. Diets consisted of 700 (HF) or 400 (LF) g/day of ammonia-treated barley straw supplemented respectively with 150 or 600 g/day of concentrate made up with barley plus either soya-bean meal (SBM) or fishmeal (FM) as the protein source, offered at 2-h intervals. Duodenal flowsof digestawere estimated by the dual-phasetechniqueusing CoEDTAand Yb-acetate as markers and (15NH4)2SO4 was infusedinto the rumento label microbial N. Bacteria were isolated from the liquid (LAB) or solid (SAB) rumendigesta. Purinebases (PB) were isolated by precipitationin an acid solution of AgN03, and microbial contribution either to the duodenalnitrogen(N) or PB were determinedby 15N measurements induodenaldigesta and bacteria.Simultaneously, therumen degradation of Nand PB contained in SBM and FM was studiedby incubating supplements in polyesterbags in the rumen.PBcontent (mmol/g dry matter)and guanine: adenine(G/A) ratio of barley strawwas 2·89 and 5·23; barley grain,7·91 and 111;SBM, 18·8 and 1·26; and FM, 58·9 and 6·96, respectively. Duodenal flow ofPB(mmol/day)was significantly higher than PB intake on all diets and G/A ratio showed a meanvalue of 0·97, similarto the ratios determined in SAB(0·80) and LAB (1·04) and muchlower than diets(1·31 to 4·32). Microbial contribution to duodenal Nflow ranged from43·3% to 61·0%, beinghigherin SBM(59·0%)thanin FM(46·7%)diets. However, microbial contribution to duodenal PB was not affected by the experimentaltreatment, accounting for proportionately 0·77 of total PB at the duodenum. Rumen degradability of PB was much higher than that of total N and in both cases degradability was higher in SBM than FM. Direct measurements of non-microbialN were significantly higher than values determined by the polyester-bagmeasurements. However, once corrected forthe endogenousN (52 mgN per kg live weight)contribution, results show edan acceptable agreement. Duodenal flow of PB non-attributable to microbes (unlabelled PB) showed a mean value of 3·25 mmol/daywithouta significanteffect of dietary treatment. However, undegradablePBsupply determinedfor0·02, 0·05 and 0·08 per h fractional out flow rates were proportionately lower than 0·025 with SBM and 0·100 with FM diets of the estimated duodenalPB flow. Despite the magnitudeof the unlabelledduodenalPB, the close agreement between G/A ratios in duodenaldigesta and bacteria suggests thatthe contribution of dietary PB to the duodenalflow was low and seemsto confirm the reliability of values obtained from polyester-bag measurements.
Individual animal model estimates of genetic correlations between performance test and reproduction traits of landrace pigs performance tested in a commercial nucleus herd
Authors: Crump R. E. , Thompson R. , Haley C. S. , Mercer J. 
Published: September 2010

AbstractBivariate individual animal model estimates of genetic and environmental correlations between reproduction traits (number born alive and average piglet weight) and performance test traits (ultrasonic backfat depth, average daily food intake, average daily gain and food conversion ratio) of Landrace pigs were calculated. The estimates were produced using a derivative-free restricted maximum likelihood algorithm to calculate likelihoods for different combinations of covariance parameters. A quadratic approximation to the likelihood surface was used to estimate the maximum likelihood values with respect to the covariance parameters. For all combinations of performance test traits with reproduction traits the resulting genetic and residual correlation estimates were low, with a maximum absolute value of 0·233 for the genetic correlation between food conversion ratio and number born alive. Standard errors of genetic correlation estimates were between 0·11 and 0·15. There is expected to have been little effect upon reproduction traits from the rigorous selection carried out upon performance test traits over the years. When incorporating reproduction data into best linear unbiased prediction analysis procedures it should be possible to analyse performance test and reproduction traits from this population separately, thereby making savings on computer resources and time required for the analysis of all traits.
Energy expenditure of cattle walking on a flat terrain
Authors: Méndez D. G. , di Marco O. N. , Corva P. M. 
Published: September 2010

AbstractA study was carried out to evaluate the effect of horizontal walking upon CO2 production rate by the carbon dioxide dilution rate technique. This was used as an indicator of animal energy expenditure. Two groups of three 18-month-old Aberdeen-Angus steers were assigned to two experiments. Average weights were 290 (s.e. 7·6) kg and 285 (s.e. 1·0) kg for experiments 1 and 2 respectively. Animals were allocated to individual pens and given 5·0 and 4·5 kg dry matter of a mixed diet for experiments 1 and 2 respectively. After a 45-day training period they were assigned to three walking treatments: 0 (T0), 3 (T3) and 6 (T2) km at 3 km/hfor 3 days in a Latin square design (3 × 3). 14C labelled sodium bicarbonate (5·4 μCi/h), diluted in carbonate-bicarbonate buffer sterile solution 0·1 mol/l, was infused for 92 h intraperitoneally with portable peristaltic pumps carried by the animals. The CO2 production rate was calculated as the ratio between the rate of infusion (μCi/h) and the specific activity of CO2 (μCi/ml CO2) in saliva samples, which were taken, in experiment 1, as an average of the day (09.00 to 16.00 h) and the night (16.00 to 09.00 h of the following day). In experiment 2 the day was divided as follows: prior to activity (09.00 to 13.00 h), activity (14.00 and 15.00 h) and post activity (16.00 h). CO2 production rate (ml CO2 per h per kg M0·75) at resting was 817 (412 kj/kg M0·75), increasing during walking to 1·46 of the resting level (T1 and T2, experiment 2) with no differences between the 1st and 2nd h of activity. One hour post activity, the CO2 production rate returned in T2 to the level of T0 but in T2 remained at 1·28 times that of T0. The average CO2 production rate during a complete day or night (experiment 1) was not affected significantly by the activity. Assuming that CO2 production rate during walking is 1·46 of resting (experiment 2) and remains at that level even at lower speeds, it can be estimated that a daily 6 km walk would increase resting energy expenditure from 1·04 when walking takes 2 h, as in this experiment (3 km/h), to 1·11 when the animal spends 6h(1 km/h).
Inclusion of grape pomace, in substitution for alfalfa hay, in diets for growing rabbits
Authors: Ferreira W. Motta , Fraga M. J. , Carabañco R. 
Published: September 2010

AbstractFour diets were formulated to study the effect of a progressive substitution of grape pomace (GP) for alfalfa hay (AH) at the rates 0, 100, 200 and 300 g/kg total weight. The control diet contained 500 g AH and 192 g acid-detergent fibre per kg dry matter (DM). In experiment 1, 32 Californian × New Zealand White rabbits were used to determine dietary nutrient apparent digestibility. The inclusion of GP decreased the apparent digestibility of crude protein (P < 0·001) and energy (P < 0·05). However, the digestible energy (DE) contents of the diets were similar because GP had a greater gross energy content than AH. In experiment 2, 36 rabbits given the same diets as in experiment 1 were used to determine several digestive and productive traits and chemical body composition (at 20kg live weight). Dietary inclusion of GP linearly decreased ammonia (P < 0·01), total volatile fatty acid concentration (P < 0·001) and the molar proportion of acetate (P < 0·05) in the caecum. Starch content in the Heal and caecal contents was low but linearly increased (P < 0·05) with increasing dietary concentration of GP. The average daily gain (from weaning at 30 days of age to 2·0 kg live weight) was not significantly affected (P > 0·10) by the diet, but the ratio gain: food linearly decreased (P < 0·001) with the GP inclusion. Dietary inclusion of GP linearly increased (P < 0·10) the fat content of the empty body of the rabbits. The efficiency of utilization of dietary DE and protein for growth were calculated by the comparative slaughter method, using the chemical body composition data of 22 suckling rabbits slaughtered at 30 days of age for the initial body composition. The efficiency of utilization of DE was not influenced by dietary GP inclusion, but GP linearly increased (P < 0·01) digestible crude protein utilization. The decrease in crude protein apparent digestibility may be the main reason that gain: food ratio was impaired in diets containing GP substituted for AH.
Influence of calving season on the interactions among reproductive disorders of dairy cows
Authors: Labernia J. , Lopez-Gatius F. , Santolaria P. , Hanzen C. , Laurent Y. , Houtain J. Y. 
Published: September 2010

AbstractThe objective of this study was to evaluate the influence of calving season on the interactions among reproductive disorders prior to conception and their effect on subsequent reproductive performance in dairy cows. Data from 3170 lactations of Holstein-Friesian cows that subsequently conceived were analysed by means of path analysis techniques. The cows were from nine commercial dairy herds in north-eastern Spain. Lactation incidence rates for retained placenta, metritis, ovarian cysts and repeat breeding (more than four artificial inseminations per conception) were 6·4, 3·7, 5·4 and 7·9%, respectively, and there were no differences between warm (May to September) and cool (October to April) calving seasons. However, our data show that calving season influenced the interrelationships among reproductive traits. Lactation number was not related to any of the path model variables for cows calving in cool seasons and retained placenta did not directly influence ovarian cysts or repeat breeding. In contrast, older cows that calved during warm seasons showed an increased risk of experiencing retained placenta, ovarian cysts and more days open; retained placenta was a direct risk factor for ovarian cysts and repeat breeding. Our data indicated that a cool season decreased interactions among reproductive disorders of dairy cows. Cows that calved in a cool environment could more effectively cope with reproductive disorders prior to conception and this fact was mainly observed in older cows.
A terminal sire selection index for UK beef cattle
Authors: Amer P. R. , Crump R. , Simm G. 
Published: September 2010

AbstractA selection index which incorporates estimated breeding values of traits recorded in the United Kingdom pedigree beef cattle breeds is described. The breeding objective is made up of commercial carcass, calving difficulty and gestation length traits. Economic values for these breeding objective traits are summarized from related studies, while partial genetic regression estimates of breeding objective traits on recorded traits are derived mainly from the literature.The selection index is described in terms of the reduction in expected genetic response from selection on the index when individual recorded traits are omitted and the expected genetic responses in breeding objective traits with selection on the index under the assumption of mass selection. Failure to record all calving traits (birth weight, calving difficulty and gestation length) resulted in a reduction in expected economic response to selection of 8% from the situation where both calving traits and production traits (400-day weight, ultrasonic fat and muscle depths, and muscling score) are recorded. With a few stated exceptions, the index is relatively robust to errors in estimates of individual parameters.It is suggested that the total index be used to assist commercial bull and semen buyers in their selection decisions but that two sub-indices for calving and production traits also be published to allow buyers to adjust emphasis on the two groups of traits depending on their individual production circumstances.
Effect of founder allele survival and inbreeding depression on litter size in a closed line of Large White pigs
Authors: Rodrigáñez J. , Toro M. A. , Rodriguez M. C. , Silió L. 
Published: September 2010

AbstractAn experimental herd of Large White pigs was established in 1931 and maintained as a closed population until 1992. The complete -pedigree (410 boars and 916 sows) has been analysed to measure along the succesive cohorts of breeding animals: thefounder representation and allele survival, the evolution ofcoancestry and inbreeding and the components of inbreeding due to each founder. Inferences about genetic and phenotypic parameters and effects of dam and litter inbreeding on litter size were obtained, using Bayesian techniques, from 2612 litter records. A significant mean reduction of 0·27 piglets born and 0·39 live born for each 10% of litter inbreeding was found but also evidence of variation among founder lineages in inbreeding depression. Alleles contributing to inbreeding depression were descendent from specific founder lineages.