bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic and epidemiological relationships between productivity and disease resistance: gastro-intestinal parasite infection in growing lambs
Authors: Bishop S. C. , Stear M. J. 
Published: August 2016

AbstractThis paper demonstrates how interactions between host genotype for resistance to an infectious disease and the epidemiology of that disease can have large influences on animal productivity and hence on breeding goals for domestic livestock. This is illustrated for the case of gastro-intestinal parasitism in lambs. A model of the parasite infection was developed to include between-animal variation (genetic, permanent and temporary environmental) for live-weight gain, food intake, larval establishment rate in the host, worm fecundity and worm mortality rate. Achieved live-weight gain was defined as the sum of potential live-weight gain under conditions of no parasite infection, a trait correlated with food intake and growth-rate reduction due to the infection. The reduction in growth-rate was calculated from cumulative larval challenge and cumulative worm mass in the lamb. Genetic parameters were then estimated for the output traits of observed live weight at 6 months of age, growth rate reduction and faecal egg count. Model parameters were chosen so that the output means and heritabilities for faecal egg count and live-weight gain mimicked field data for Scottish Blackface lambs and growth-rate reductions were proportionately 0·25 , on average. The model predicted a weak phenotypic correlation (mean = -0·10) between observed live weight and faecal egg count, the indicator of resistance but a stronger favourable (negative) genetic correlation between these traits (mean = -0·27). The severity, or epidemiology, of the disease greatly influenced the results - the genetic correlation between observed live weight and faecal egg count strengthened from -0·02 to -0·46 as the disease severity changed from mild to severe. Selection for reduced faecal egg count resulted in large correlated increases in live-weight gain, more than twice that predicted by quantitative genetic theory, due to the reductions in growth rate losses as the disease challenge to the animals decreased. Conversely, selection for increased live-weight gain resulted in reductions in faecal egg count close to expectations. This asymmetry of selection response emphasizes the epidemiological benefits obtainable from selection for resistance to infectious chronic diseases - such selection will result in improvements in both animal health and productivity not seen when selection is for improved productivity, alone. Breeding goals should be designed to take account of such effects.
The effects of synchronizing the rate of dietary energy and nitrogen supply to the rumen on the metabolism and growth of ram lambs given food at a restricted level
Authors: Witt M. W. , Sinclair L. A. , Wilkinson R. G. , Buttery P. J. 
Published: August 2016

AbstractThe effects of diets formulated to have two rates of organic matter (OM) release and to be either synchronous or asynchronous with respect to their hourly release of OM and nitrogen (N) in the rumen on N retention, microbial N production, growth and metabolism of ram lambs offered food at a restricted level was studied in two experiments. Four diets were formulated to differ in their rate and extent of OM and N release in the rumen based on the sum of in situ degradability data of the ingredients. All diets were formulated to have a similar metabolizable energy (10·4 MJ/kg dry matter (DM)), crude protein (140 g/kg DM) and daily ratio of N : OM released (34 g N per kg OM) and were either synchronous or asynchronous with respect to their hourly N : OM release. The four diets were slow energy, synchronous (SS), slow energy asynchronous (SA), fast energy, synchronous (FS) and fast energy asynchronous (FA). In both experiments the diets were offered at a rate of 1·75 maintenance energy requirements as two equal meals at 09:00 and 17:00 h. In experiment 1 there was no significant effect of diet on OM apparent digestibility or N retention. Lambs given diet FS had the highest daily production of allantoin (7·82 mmol per day; P < 0·05) and microbial N (7·80 g/day; P < 0Ό5). Hourly plasma urea and ß-hydroxy butyrate (3-OHB) concentrations exhibited a cyclical trend between meals with maximum concentrations occurring within 3 h of feeding and were higher in lambs given diet FA.In experiment 2 the four diets were offered to 32 growing ram lambs. Animals given synchronous diets (SS and FS) had a significantly higher live-weight gain than those given asynchronous diets (SA and FA; (132 g/day v. 107 g/day respectively; P < 0·001). Food conversion efficiency (FCE; kg gain per kg DM intake) was improved proportionately by 0·23 in animals offered synchronous diets compared with asynchronous diets (P < 0·001). There was little effect of diet on carcass composition except kidney fat, which was greater in lambs offered the synchronous diets (P < 0·01). Plasma 3-OHB concentrations were higher throughout the growth period in lambs given diet FA whilst plasma urea concentrations were greater in lambs given the diet SS. In conclusion, greater attention to the formulation of diets to be synchronous for their hourly release of N : OM in the rumen can improve the growth rate and FCE of lambs. This effect may be due to an improvement in energy rather than N metabolism.
The use of cumulative gas production technique to characterize changes in the fermentation characteristics of rumen contents following variable periods of starvation and grazing in dairy cows
Authors: Chilibrostet P. , Williams B. A. , Tamminga S. , Calabro S. 
Published: August 2016

AbstractThe effect of the duration of grazing (experiment 1) and starvation time and placement in the rumen of inert bulk material before grazing (experiment 2), on the rumen content ferment ability, was investigated by means of measuring cumulative gas production. In experiment 1, a comparison was made of four durations of grazing (1, 1·75, 2·50 and 3·25 h) after overnight starvation. Rumen samples taken from the cows after 1 h of grazing had higher values of total accumulated gas with less (P < 0·05) time required to reach the maximum fermentation rate than cows grazed for 3·25 h. Following grazing, a 7·75·h starvation period was imposed on the four treatments. The extent of fermentation was significantly lower (P < 0·01) after starvation than immediately after grazing (49·7 v. 60·8% of incubated dry matter (DM), respectively). Experiment 2 consisted of a factorial combination of two durations of starvation before grazing (16·5 (LS) and 2·5 (SS) h) with the presence or absence in the rumen of 12·5 kg of a synthetic indigestible material. Before grazing the total accumulated gas production was less (P < 0·05) for the LS than for the SS cows. After the grazing session, the total gas of rumen samples from the LS cows was significantly higher (P < 0·05) than for the SS cows.This was in agreement with the observed higher DM intake during grazing and DM rumen pools after grazing in LS cows. For both starvation periods, the presence of inert rumen bulk led to a higher total gas, a shorter half-time and less DM left unfermented. The measurement of fermentation kinetics by cumulative gas production was suitable to detect changes in rumen content fermentation patterns due to the clearance of material from the rumen (effect of starvation) or DM intake during the grazing sessions.
Selection with control of inbreeding in populations with overlapping generations: a comparison of methods
Authors: Sonesson A. K. , Grundy B. , Woolliams J. A. , Meuwissen T. H. E. 
Published: August 2016

AbstractMethods that maximize genetic response in populations with overlapping generations while controlling rate of inbreeding by constraining the average relationship among selection candidates were compared. Firstly, computer simulations of closed nucleus selection schemes showed that a two-stage optimization algorithm approach, where the distribution of parents within and thereafter over age classes was optimized resulted in different breeding schemes than an approach that performed an iteration on this distribution. It yielded significantly lower annual genetic gain (0·194 v. 0·223 σpunits), fewer animals selected (21·9 v. 26·4) and longer generation intervals (2·38 v. 1·68 years) but maintained the rate of inbreeding closer to its constraint. In large schemes, iteration may be computationally the only feasible method for the optimization of parents across age classes. Secondly, the use of conventional relationships for constraining inbreeding was compared with that of augmented relationships, which do not depend on the level of inbreeding. Both relationships resulted in very similar breeding schemes, but the use of augmented relationships avoids correction of the current level of inbreeding. Thirdly, a constraint of the rate of inbreeding on a per year basis was compared with a constraint on a per generation basis. When optimizing per generation, the generation interval was shorter compared with a scheme where an analogous annual restriction was in place (2·01 v. 2·38 years) and the annual rate of genetic gain was higher (0·214 v. 0·194 σpunits).
Growth and carcass characteristics of three lamb genotypes finished on the same level of feeding
Authors: McClintont L. O. W. , Carson A. F. 
Published: August 2016

AbstractThis study investigated the efficiency of growth and the carcass characteristics of 24 Greyface (Border Leicester × Scottish Blackface), 24 Texel (12 purebred and 12 Texel × Texel-Greyface) and 24 Rouge (12 purebred and 12 Rouge × Rouge-Greyface) lambs finished on the same level of feeding. The efficiency of live-weight gain (kg/MJ) was higher in Greyface compared with Texel lambs (P< 0·01). The efficiency of empty body-weight gain (kg/MJ) was higher in Greyface (P< 0·01) and Rouge (P< 0·05) compared with Texel lambs. The efficiency of carcass gains (kg/MJ) tended to be higher in Greyface and Rouge compared with Texel lambs (P= 0·07). The efficiency of non-carcass component gains (kg/MJ) was also higher in Greyface compared with Texel lambs (P0·05). Carcass water, protein, lipid and ash gains did not vary significantly between the genotypes, however carcass energy gain tended to be higher in Greyface and Rouge compared with Texel lambs (P= 0·08). The relative proportions of water, protein, lipid and ash in carcass gains did not vary significantly between the genotypes. At the end of the experiment carcass water content was higher in Texel compared with Greyface lambs (P< 0·05) and carcass ash content was lower in Texel compared with Greyface (P< 0·01) and Rouge (P< 0·05) lambs. The concentration of saturated fatty acids was higher in Greyface compared with Rouge lambs (P< 0·001) and higher in Rouge compared with Texel lambs (P< 0·05). Monounsaturated fatty acid concentrations were higher in Rouge compared with Greyface lambs (P< 0·05) and higher in Texel compared with Rouge lambs (P< 0·001). Polyunsaturated fatty acid concentrations were higher in Rouge and Texel compared with Greyface lambs (P< 0·01). The ratio of n-6:n-3 fatty acids was lower in Rouge compared with Greyface lambs (P< 0·05).The efficiency of empty body gain was higher in male compared with female lambs (P< 0·05). Carcass water (P< 0·01) and protein (P< 0·05) gains were higher in male lambs. At the end of the experiment male carcasses contained a higher content of water (P< 0·05), protein (P< 0·01) and ash (P= 0·07), and a lower lipid (P< 0·05) and energy (P< 0·001) content. Carcass lipids from male lambs contained a higher concentration of polyunsaturated fatty acids (P< 0·001) and tended to contain a lower concentration of saturated fatty acids (P = 0·06).
Effects of cow families on type traits in dairy cattle
Authors: Roughsedge T. , Brotherstone S. , Visscher P. M. 
Published: August 2016

AbstractThe component of variance attributable to maternal lineage for type traits in the UK Holstein Friesian dairy population was estimated. First lactation type classification records of 33 325 contemporary cows, classified between 1996 and 1998 were used in the analysis. Maternal pedigree records were traced back to 1960 to establish maternal lineages. The tracing resulted in cows being assigned to 10 332 cow families with more than one cow per family. Sixty-six percent of the cows were in families of less than five. The traits comprised 16 linear type traits, a total score trait, four composite scores and measures of temperament and ease of milking. Univariate analysis of each trait was performed using residual maximum likelihood, with and without a maternal lineage component. A principal component analysis used a scree test to determine the number of independent traits being considered in-order to establish a level of significance for the test statistic. It was found that eight principal components were responsible for the variation in type. The composite body score trait was found to have a 1·5% component of maternal lineage variance, significant at the 5% level. No other traits showed a significant maternal lineage variance component.
Estimates of genetic parameters for growth and skeletal measurements in Thai swamp buffalo
Authors: Meyer K. , Graser H. -U. , Na-Chiangmai A. 
Published: August 2016

AbstractEstimates of genetic parameters were obtained for weight, hip height, heart girth and shoulder to pin length measurements on Thai swamp buffalo, recorded at birth and weaning. Direct heritability estimates were 0·26 for weights at both ages and were low for skeletal measurements, ranging from 0·11 to 0·19. Low values could, in part at least, be caused by inaccuracies in recording. All traits were subject to maternal effects, permanent environmental maternal effects on traits recorded at weaning explaining proportionately up to 0·14 of the total variation. Estimates of genetic (direct and maternal) and permanent environmental correlations between traits recorded at the same time were high throughout, ranging from 0·83 to 0·97 for additive genetic effects and being close to unity otherwise. Except for heart girth measured at weaning, there appeared to be comparatively little genetic association between traits recorded at different times, direct additive correlation estimates ranging from 0·18 to 0·55 in contrast to estimates of 0·38 to 0·65 for correlations with heart girth at weaning.
Genetic modelling of daily milk yield using orthogonal polynomials and parametric curves
Authors: Brotherstone S. , White I. M. S. , Meyer K. 
Published: August 2016

AbstractRandom regression models have been advocated for the analysis of test day records in dairy cattle. The effectiveness of a random regression analysis depends on the function used to model the data. To investigate functions suitable for the analysis of daily milk yield, test day milk yields of 7860 first lactation Holstein Friesian cows were analysed using random regression models involving three types of curves. Each analysis fitted the same curve to model overall trends through a fixed regression and random deviations due to animals. Curves included orthogonal polynomials, fitted to order 3 (quadratic), 4 (cubic) and 5 (quartic), respectively, a three-parameter parametric curve and a five-parameter parametric curve. Sets of random regression coefficients were fitted to model both animals’ genetic effects and permanent environmental effects. Temporary measurement errors were assumed independently but heterogeneously distributed, and assigned to one of 12 classes. Results showed that the measurement error variances were generally lowest around peak lactation, and higher at the beginning and end of lactation. Parametric curves yielded the highest likelihoods, but produced negative genetic associations between yield in early lactation and later lactation yields, while positive genetic correlations across the entire lactation were estimated with all models involving orthogonal polynomials. The fit of models using orthogonal polynomials to model test day yield was improved by including higher order fixed regressions.
The flexibility of feeding patterns in individually housed pigs
Authors: Bornett H. L. I. , Morgan C. A. , Lawrence A. B. , Mann J. 
Published: August 2016

AbstractGroup-housed pigs may be prevented from expressing their desired feeding pattern by more dominant individuals in the group. Indeed, when compared with individually housed pigs, group housed pigs eat less frequent, but larger meals. Therefore, it would be advantageous for pigs to have flexible feeding patterns in order to decrease the impact of group housing. The aim of this study was to assess the flexibility of feeding patterns by restricting the time of access to food of pigs previously given food ad libitum and then returning them to 24-h access. Thirty-two Large White x Landrace pigs were used in an experiment of two blocks (16 pigs per block) each comprising three, 2-week periods. In each block; during period 1, all pigs were allowed 24-h access to food after which, in period 2, eight of the pigs had access to the feeder restricted between 11:00 and 13:00 h of each day. The remaining eight pigs continued on 24-h access to food and acted as controls. In period 3, all pigs were again returned to 24-h access to food. Daily feeding pattern and food intake were recorded throughout. Behavioural observations in the form of scan samples were made and pigs were weighed twice a week. In period 2 the restricted pigs had fewer visits to the feeder per day, 34·0 v. 70·1 (P < 0·001); of a longer duration, 98·3 v. 64·5 s (P < 0·01); with a higher food intake per visit, 64·9 v. 33·3 g (P < 0·001) than the control pigs. Daily food intake and live-weight gain were lower (P < 0·001) for the restricted pigs in period 2 than for the control pigs. Restricted pigs spent more time rooting (P < 0·05), and less time sleeping (P < 0·05) than the control pigs in period 2. In addition, there was a trend for pigs to spend more time alert in the observation session prior to access to food in the second period when they were restricted and they made attempts to gain access to the feeders in this session. An indication of flexibility was gained by comparing feeding behaviour and time budgets between periods 1 and 3. The pigs that experienced a period of restricted feeding either resumed their previous behaviour or showed the same trend as the controls. In periods 1 and 3 daily feeder visits were 66·2 and 68·1 for control pigs, and 65·6 and 67·1 for restricted pigs. Mean durations of visits were 79·3 and 47·5 s, and 74·4 and 61·7 s respectively. It was concluded that feeding behaviour was flexible and time budgets were resilient across periods.
Choices by lactating cows between concentrates high or low in digestible undegraded protein
Authors: Lawson R. E. , Redfern E. J. , Forbes J. M. 
Published: August 2016

AbstractTo determine whether lactating cows select a nutritionally appropriate diet when given grass silagead libitumand a choice of concentrates high or low in digestible undegradable protein (DUP), 24 mid-lactation Holstein-Friesian cows were given, in different 3-week periods, a concentrate high in DUP (HP), one low in DUP (LP), or a choice between the two (CHOICE), all at an allowance of 5·4 kg dry matter per day. Milk yield was significantly lower, and silage intake slightly but significantly higher, on LP than on either HP or CHOICE. The mean proportion of HP taken in the CHOICE period was 0·47 which was greater than the proportion required to satisfy the cows’ calculated requirements for effective rumen degradable protein, DUP or metabolizable protein but not significantly different from the ratio of 0·50 expected if no choice was made. Individual cows had a strong tendency initially to continue to eat from the feeder from which they had obtained concentrates in the period before CHOICE but this changed to eating significant amounts of both foods within about a week. The fact that the relationship between the proportion of HP in the concentrate intake and milk protein output was significant and positive, and became more so as the CHOICE period progressed, supports the hypothesis that protein demand was directing diet selection but must be viewed with caution as it was heavily influenced by the results of one animal: the highest-yielding cow which also chose to eat the greatest proportion of HP.
Dietary choline requirement of juvenile grass shrimp (Penaeus monodon)
Authors: Shiau S. Y. , Lo P. S. 
Published: August 2016

AbstractA feeding trial was conducted to determine the dietary choline requirement of juvenile grass shrimp, Penaeus monodon. Purified basal diets were formulated using vitamin-free casein (containing 370 mg choline per kg) as the protein source. Graded levels (0, 300, 600, 1000, 2000, 4000, 7000, and 10 000 mg choline per kg diet) of choline chloride were added to the basal diet, resulting in eight dietary treatments in the experiment. Each diet was given to three replicate groups of shrimp initially averaging 1·18 (s.d. 0·01) g for 8 weeks. Weight gain was highest in shrimp given the diets supplemented with 7000 and 4000 mg choline per kg diet, followed by the groups given 2000 mg/kg, then 1000 and 600 mg/kg, and finally 300 mg/kg and the unsupplemented control group (P < 0·05). Shrimp given diets supplemented with 7000 and 4000 mg choline per kg diet had significantly higher food efficiency and survival than those given diet with 300 mg choline per kg or the control diet. Higher body crude protein and choline concentrations were recorded in shrimp given diets supplemented with 4000 and 7000 mg choline per kg diet than shrimp given diets with ≤600 mg choline/kg and ≤2000 mg choline per kg, respectively. Analysis by polynomial regression of weight gain and body choline concentration for P. monodon gave a maximum at about 6000 mg/kg. Taking into account the choline concentration of the unsupplemented basal diet, the optimal dietary choline requirement for growing P. monodon is about 6200 mg/kg.
Re-evaluation of the vitamin E requirements of juvenile tilapia (Oreochromis niloticus ✕ O. aureus)
Authors: Shiau S. Y. , Shiau L. F. 
Published: August 2016

AbstractA 10-week feeding trial was conducted to re-evaluate the level of dietary vitamin E (DL- α-tocopheryl acetate) that was adequate for juvenile tilapia Oreochromis niloticus ✕ O. aureus given diets containing two dietary lipid concentrations. Purified diets with eight levels of vitamin E (0, 25, 50, 75, 100, 150, 200, 400 mg/kg diet) at either 50 or 120 g lipid per kg were each given to three replicate groups of tilapia (mean weight: 0·69 (s.e.0·02) g) reared in a closed, recirculating system. Food efficiency and protein deposition were significantly (P < 0·05) higher in fish given 50 mg vitamin E per kg diet and 75 mg/kg diet in the 50 and 120 g lipid per kg groups respectively, compared with fish given the unsupplemented control diet. Mortality of fish was not affected by dietary treatment. Weight gain and liver microsomal ascorbic acid-stimulated lipid peroxidation data analysed by broken-line regression indicated that the optimum dietary vitamin E requirements in juvenile tilapia are 42 to 44 mg vitamin E per kg and 60 to 66 mg vitamin E per kg in 50 and 120 g lipid per kg diets, respectively.