bluuebunny/crossref_metadata_2025 huggingface dataset:
Heart rate responses and plasma cortisol concentrations in ewes: comparison between cervical and laparoscopic intrauterine insemination and their associated handling procedures
Authors: Khalid M. , Haresign W. , Bradley D. G.
Published: September 2010

This study consisted of two experiments. In experiment 1, stress responses of sheep which were restrained either in a laparoscopy cradle or a roll-over cradle were compared. The results of this experiment indicated that restraint in roll-over cradle is less (P < 0·05) stressful than that in a laparoscopy cradle when assessed in terms of the elevation and duration of both the mean heart rate and plasma cortisol responses. Experiment 2 compared the stress responses of sheep subjected to restraint in a laparoscopy cradle, restraint in a laparoscopy cradle with intrauterine artificial insemination (AI) by laparoscopy, minimal restraint with cervical AI or restraint in a roll-over cradle plus foot-trimming. All treatments resulted in significant elevations in both heart rate and plasma cortisol concentrations (F < 0·001). The peak heart rate was significantly (P < 0·05) higher in ewes subjected to cervical AI than in those subjected to intrauterine insemination, with other treatments intermediate. The peak cortisol response did not differ among different treatments. The duration over which both the mean heart rate and -plasma cortisol concentrations remained significantly elevated above pre-treatment concentrations did not differ among treatment groups. The results of this study suggest that while restraint using a laparoscopy cradle is more stressful than that using a rollover cradle, the stress inflicted by intrauterine insemination by laparoscopy itself is no greater than that due to restraint using the laparoscopy cradle alone, cervical AI or the management practice offoot-trimming using a rollover cradle.
The rôle of cortisol and β-endorphin in the response of the immune system to weaning in lambs
Authors: Rhind S. M. , Reid H. W. , McMillen S. R. , Palmarini G.
Published: September 2010

The relationship between weaning stress-induced changes in stress hormone profiles and immune function was investigated in groups of 10 lambs immunized against adrenocorticotrophic hormone (ACTH; treatment A) or fi-endorphin (treatment B) to reduce the circulating concentrations of cortisol and fi-endorphin respectively. Control animals (treatment C) were immunized against a porcine thyroglobulin carrier protein. Application of weaning stress was associated with significantly elevated plasma cortisol concentrations but no significant increase in fi-endorphin concentrations in C lambs. Immunization against ACTH suppressed the post-weaning increase in cortisol concentration. This was associated with a transient reduction in the lymphocyte stimulation response to keyhole limpet haemocyanin (KLH) antigen in the A animals but there was no effect on the antibody response or interferon-y production by antigen stimulated lymphocytes. There were no significant effects of immunization against fi-endorphin on the capacity to mount antibody or cell-mediated immune responses. It is concluded that weaning stress-induced increases in cortisol did not inhibit the immune response. Since cortisol concentrations and the cell mediated immune response at 8 days after immunization were positively associated it is concluded that these indices are not independent measures of stress.
Competitive ability of rams selected for high and low levels of sexual performance
Authors: Erhard H. W. , Price E. O. , Dally M. R.
Published: September 2010

The objective of this study was to determine any differences in the competitive ability of rams differing in levels of sexual performance. Twenty sexually experienced Targhee-type rams were preselected from a population of 95 males for exhibiting relatively high and low ejaculation rates when individually exposed to oestrous ewes for 30 min. Each of 10 high performers (HP) were paired with each of 10 low performers (LP) on three occasions when competing for food (after food deprivation) and twice when competing for an oestrous female. Tests were 5 min in duration. Food-deprived HP and LP rams were equally aggressive when competing for a source offood that could only be accessed by one ram at a time. Time offeeding by HP and LP rams did not differ. HP rams spent more time with the oestrous ewe and attained more mounts in a greater number of pairings than LP rams even though HP and LP rams did not differ in number of successful agonistic interactions (active displacements and successful defences) when competing for the ewe. It was concluded that HP and LP rams, taken as groups, do not differ in their basic competitive ability and that the greater mating success of HP rams can be explained by their higher levels of libido.
Meat production from crossbred and domestic yaks in China
Authors: Jialin B. , Mingqiang W. , Zhonglin L. , Chesworth J. M.
Published: September 2010

Female domesticated yaks were artificially inseminated with semen taken from wild yaks and the offspring used to form a nucleus breeding herd of crossbred animals. The meat production of the first generation (F2 × F2) frombreeding within the nucleus herd was assessed by slaughter and carcass dissection of males. One group (no. = 14) was slaughtered at 6 months of age and the second (no. = 12) at 18 months. Crossbred yaks were significantly heavier (P < 0·01) at 6 months (74·7 (s.e. 10·41) kg v. 59·8 (s.e. 10·23) kg) and at 18 months (150·5 (s.e. 56·1) kg v. 117·7 (s.e. 17·4) kg) than domesticated ones. The killing-out proportion (0·47) was similar at both ages and for both groups of animals. Carcass weight, meat weight and the yield of prime cuts were higher for crossbred animals than for domestic yak at both ages.
The value of crossbreeding information in selection of poultry under a dominance model
Authors: Uimari P. , Gibson J. P.
Published: September 2010

A stochastic simulation was used to investigate the value of crossbreeding information in a two line crossbreeding system in poultry under different genetic scenarios. Populations consisted of 25 sires and 250 dams, which were mated to produce both purebred and crossbred progeny. The next generation parents were selected either based on purebred information (PLS) (sib means, and own performance for females) or additional crossbred sib means were included (CCPS). The trait under selection was controlled by 20 loci with varying degree of dominance. Pure lines differed in initial allele frequencies. If the trait was controlled by loci with partial dominance, little or no extra benefit was obtained from including crossbred information over the pure line information. Under complete dominance and overdominance CCPS outperformed PLS. As a practical rule, CCPS is better than PLS if the ratio between dominance variance and total genetic variance is around 0·3 or higher. In this case the most probable cause of the dominance variation is loci with full or overdominance.
Supplementation of grass silage-based diets with small quantities of concentrates: strategies for allocating concentrate crude protein
Authors: Aston K. , Fisher W. J. , McAllan A. B. , Dhanoa M. S. , Dewhurst R. J.
Published: September 2010

Fifty-five multiparous Holstein-Friesian cows were used to evaluate the short- and long-term effects of varying the crude protein (CP) content of concentrates offered at a low level (5 kg/day) along withad libitumaccess to a high quality grass silage. Three dietary treatment groups in lactation weeks 4 to 22 received concentrates containing either 156 (L), 247 (M) or 338 (H) g CP per kg dry matter; from weeks 13 to 21, half of the L animals changed over to the H concentrate and vice versa so that there were five treatment groups (LL, LH, MM, HL and HH). Feeding M or H compared with L increased silage voluntary intakes (P<0·05) and the yields of milk (P<0·05), fat (P< 0·05) and protein (P< 0·01). Milk protein concentration increased with level of concentrate CP (P< 0·05). Pattern of concentrate CP supply (comparison ofLH, MM and HL) had no significant effect on intake or yields of milk and milk solids across the experiment (weeks 4 to 21), though cows gained less weight on treatment HL than on LH (P<0·05) or MM. Intake, milk and component yields were all markedly affected by a change in concentrate CP at week 13; there were positive effects of additional CP (LLv.LH) and negative effects of reduced CP (HHv.HL) on silage intake (P<0·05), as well as milk yield (P< 0·001), milk protein yield (P< 0·001) and milk protein concentration (P< 0·001). Responses to increased concentrate CP were of a similar magnitude in early and midlactation; extra concentrate CP can recover depressed yields and concentrations of milk protein in established lactation. Production responses to concentrate CP involved a concomitant increase in silage voluntary intake.
Effect of undernutrition and refeeding on digestion in Bos taurus and Bos indicus in a tropical environment
Authors: Grimaud P. , Richard D. , Kanwé A. , Durier C. , Doreau M.
Published: September 2010

The effect of underfeeding and ref eeding on digestion was studied in Bos taurus and Bos indicus cows. Eight nonlactating cows, four B. taurus and four B. indicus (live weight 156 kg and 207 kg respectively) were first given a forage-based diet at a level above energy maintenance requirements for 4 weeks (3·65 and 4·66 kg dry matter (DM) per day respectively for B. taurus and B. indicus). They were then restricted at a low level of intake for 2 months (1·83 and 2·33 kg DM per day respectively for B. taurus and B. indicus) and finally refed at the first level for 2 months. Digestion measurements were made before the underfeeding period, at 3 and 8 weeks of underfeeding and at 3 and 8 weeks ofref eeding. Organic matter apparent digestibility decreased with underfeeding and increased with refeeding (0·637, 0·591, 0·652, 0·692 and 0·669 in B. taurus and 0·674, 0·560, 0·580, 0·698 and 0·692 in B. indicus, respectively 1 week before, 3 and 8 weeks after underfeeding, and 3 and 8 weeks after refeeding). This lower apparent digestibility at low level of intake was not expected either by ruminal particle retention time, which increased when intake decreased, or by measurements ofmicrobial activity: DM degradability measured in situ and ruminal particle size did not vary with level of intake. An effect of the length of underfeeding and refeeding was seen: the apparent digestibility tended to increase after several weeks of undernutrition and was higher after refeeding than before underfeeding. No difference was observed between the two genotypes.
Growth and body composition of highly selected boars and gilts
Authors: Van Lunen T. A. , Cole D. J. A.
Published: September 2010

An experiment was conducted to measure the growth and body composition changes of highly selected boars and gilts from 10 to 150 kg live weight. Thirty boars and 30 gilts were given food ad libitum and two pigs of each sex were slaughtered at 10-kg increments from 10 kg to 150 kg live weight at which time the chemical composition of the body was determined. Boars and gilts exhibited different patterns of growth, nitrogen deposition rate (NDR) and lipid deposition rate (LDR) with boars exhibiting a sharp peak in daily live-weight gain and NDR while gilts exhibited almost a flat response curve over the age and weight range tested. Gilts experienced a peak in LDR at a lighter weight than boars (75·8 v. 100·5 kg) while NDR peaked at the same weight for both sexes (70·8 kg). Maximum NDR for boars and gilts was 37·7 and 28·1 glday (235·5 and 175·5 glday protein deposition rate) respectively. The Gompertz growth equation [Y = A + C × EXP (−EXP (−B ×(X−M)))] was shown to accurately represent the growth trajectory, while the logarithmic derivative of the allometric equation [Y = aXb] was used to determine live weight and body composition relationships. Combined sex relationships indicated that total body nitrogen and lipid concentrations increased at the same rate. A quadratic equation for the prediction of NDR based on live weight was developed for this genotype (NDR = 24·06 + 0·34 W − 0·002W2). In conclusion, the results provide a basis for comparison of body composition and growth patterns between the highly selected genotype tested and pigs from other genetic backgrounds. Sex effects exist for growth and body composition but combined sex prediction equations can be used to estimate NDR potential.
Ileal digestibility of amino acids in pigs given a barley-based diet with increasing inclusion of lucerne leaf meal
Authors: Reverter M. , Lindberg J. E.
Published: September 2010

Ileal digestibility of amino acids in barley-based diets with increasing inclusion of lucerne leaf meal (LLM; 0, 50, 100 and 200 g/kg) was studied in a change-over experiment with post-valve T-caecum cannulated growing pigs. The apparent Heal digestibility of crude protein, as well as of most of the essential (EAA) and non-essential amino acids (NEAA) was not significantly affected by the dietary inclusion of LLM. The exceptions were cystine, methionine, phenylalanine, glutamic acid and serine, all of which showed a significant (P< 0·05) reduction in apparent Heal digestibility with increasing inclusion of LLM. In contrast, the calculated true Heal digestibility of all EAA (with the exception of arginine and lysine) and the NEAA glutamic acid and serine were significantly (P< 0·05) reduced with the inclusion of LLM. Associated with an increased crude protein intake, there was a significant (P< 0·05) increase in the amount of absorbed EAA when the proportion of LLM was increased in the diet. With increasing proportion of fibre in the diet, there was a significant (P< 0·05) increase in the Heal flow of glucosamine.

It can be concluded from the present data that the inclusion of LLM in a barley-based diet for growing pigs will result in an improvement in the absorbed amino-acid profile due to a significant increase in the absorption of all of the EAA.
The effects of including white clover in perennial ryegrass swards and the height of mixed swards on the milk production, sward selection and ingestive behaviour of dairy cows
Authors: Phillips C. J. C. , James N. L.
Published: September 2010

Two experiments were conducted with dairy cows to examine the effects of including white clover in perennial ryegrass swards and of offering the cows a choice between tall and short mixed perennial ryegrass/white clover swards. In the first experiment, cows grazed a perennial ryegrass sward (treatment Prg); a mixed sward of perennial ryegrass and white clover (treatment WC); treatment Prg during the night and treatment WC during the day (treatment Prg night/WC day); or they were offered a choice between Prg and WC (treatment Prg/WC). Cows in treatment WC produced more milk than cows in treatment Prg, with cows in Prg night/WC day and Prg/WC intermediate. The milk fat content of cows in treatment Prg was greater than in the other three treatments. When cows were offered both mixed grass/clover and pure grass swards (treatments Prg night/WC day and Prg/WC) they exhibited a partial preference for the WC sward and grazed it to a lower herbage height than the pure grass sward. In the second experiment, cows were offered a WC sward at 6 or 3·5 cm sward surface height, or a choice between pastures at the two heights. Cows offered only the tall sward produced most milk, and those offered only the short sward produced the least. Milk fat content was reduced for cows offered only the tall sward. Cows offered a choice of the tall or short swards spent longer grazing in total than the cows offered only tall or only short swards but there was no difference in the time spent grazing the tall and short swards.
The effects of concentrate energy source on silage feeding behaviour and energy utilization by lactating dairy cows offered grass silages with differing intake characteristics
Authors: Keady T. W. J. , Mayne C. S.
Published: September 2010

The effects of concentrate energy source on feeding behaviour and energy utilization, when offered with grass silages of differing intake characteristics, were studied in lactating dairy cows. A total of five silages, which differed in fermentation and intake characteristics, were prepared. Silages A, B and D and silages C and E were harvested from primary regrowths and secondary regrowths respectively of predominantly perennial ryegrass swards. Herbage was ensiled either pre-wilted or unwilted and either untreated or treated with a bacterial inoculant or formic acid based additives. Five concentrates (0s, 25s, 50s, 75s and 100s) were formulated to contain similar concentrations of crude protein, effective rumen degradable protein and metabolizable energy (ME) but using different carbohydrate sources to achieve a wide range of starch concentrations. The silages were offered ad libitum, supplemented with 10 kg concentrates per head per day. In experiment 1, a partially balanced change-over design experiment involving 50 lactating dairy cows was undertaken to examine the effects of concentrate energy source on silage feeding behaviour. Silages A, B, C, D and E were each supplemented with concentrates Os, 25s, 50s, 75s and 100s. Concentrate energy source did not alter (P > 0·05) silage feeding behaviour. The number of meals per day decreased (P < 0·01) as silage dry-matter concentration increased. Experiment 2, a completely randomized experiment involving 18 lactating dairy cows, was undertaken to examine the effects of concentrate energy source on energy utilization with cows offered silages B, C and D. These were supplemented with 10 kg/day of concentrates Os, 50s and 100s. Concentrate energy source had little effect (P > 0·05) on ME intake, energy output or on the efficiency of utilization of ME for lactation (k1). In experiment 3, the effect of concentrate energy source on silage preference was examined in a factorial design experiment involving 12 lactating dairy cows. Silages B, C and D were supplemented with concentrates Os, 50s and 100s. Concentrate energy source did not alter (P > 0·05) silage preference. It is concluded that with silages of differing fermentation and intake characteristics but of similar digestibility, concentrate energy source had no effect on feeding behaviour, silage preference or energy utilization. Furthermore there was no evidence of concentrate energy source by silage type interactions on silage feeding behaviour and preference, or energy utilization.
Adaptation of cattle to tannins: rôle of proline-rich proteins in oak-fed cattle
Authors: Makkar H. P. S. , Becker K.
Published: September 2010

Saliva and faecal samples were collected from hill cattle (no. = 10) given tannin-rich oak (Quercus incana) leaves in the north-west Himalayan region of India. Amino acid composition of the saliva samples after thawing to remove precipitated proteins by centrifugation, and dialysis (molecular weight cut off: 3500) to remove small moieties revealed 6·4 (s.d. 0·6) % proline, 15·6 (s.d. 0·6) % glutamine plus glutamate and 9·2 (s.d. 1·0) % glycine on molar basis. For Holstein Friesian cattle (no. = 4) which had no history of consumption of tannin-containing foods, these values were 6·5 (s.d. 0·4) %, 15·2 (s.d. 0·5) % and 9·8 (s.d. 0·7) % respectively. Proline concentration in the proteins present either as free or as tannin-protein complexes in the lyophilized faecal samples from hill cattle was 4·7 (s.d. 0·2) % (on molar basis) of the total amino acids and 5·3 (s.d. 0·2) % in Holstein Friesian cattle. In the faeces of oak-fed cattle, the tannin and condensed tannin levels on dry-weight basis were 0·81 (s.d. 0·20) % as tannin acid equivalent and 0·06 (s.d. 0·04) % as leucocyanidin equivalent respectively. For tannic acid, the relative affinity of salivary proteins, using the competitive binding assay, was about six-times higher than that of bovine serum albumin (BSA) and was of the same order as that of gelatin. Turbidity of complexes formed between salivary proteins or BSA and tannic acid showed proportionately about 0·50 lower turbidity for salivary proteins in 0-2 mol/I acetate buffer (pH 4·9 containing 0·17 mol/l NaCl) and proportionately about 0·84 lower turbidity in distilled water. The results suggest that unlike rats or mice, the proline-rich proteins do not appear to be of any physiological significance in the adaptation of cattle to tannins. However, the salivary proteins of cattle though not rich in proline, have a high affinity for tannins and these proteins have a high tendency to form soluble tannin-protein complexes.
Genetic studies of prolificacy in New Zealand sheep
Authors: Davis G. H. , Morris C. A. , Dodds K. G.
Published: September 2010

Data on ovulation rate, embryo survival and litter size have been analysed from the 1988-96 records collected at AgResearch's Woodlands Research Station on 2180 elite (highly prolific) ewes of three breeds: Romney, Coopworth and Perendale. The Romneys included a subgroup found to carry the sex-linked Inverdale high prolificacy gene. Foundation animals for all breeds were screened on high litter size (lambs born, alive or dead, per ewe lambing) from industry flocks. Prior to being transferred to Woodlands between 1979 and 1984, their average litter size was 2·66. Ovulation rates for descendants of the foundation ewes averaged 2·15 (Romney), 2·43 (Coopworth), 2·15 (Perendale) and 2·96 for the Romney subgroup carrying the Inverdale gene. Embryo survival averaged 0·84 except for a low value in Inverdales (0·76). Using a restricted maximum likelihood model, with full relationship matrix, the within-breed heritability of ovulation rate over all ages and breeds (excluding Inverdale) was 0·14 (s.e. 0·03), with repeatability 0·26 (s.e. 0·02). Litter size averaged 1-80 (Romney), 2·05 (Coopworth), 1·76 (Perendale) and 2·17 (Inverdale). The heritability estimate for litter size (excluding Inverdale) was 0·073 (s.e. 0·018), from data for all ages. The genetic correlation between ovulation rate and litter size was 0·91 (s.e. 0·08). The standard deviation for ovulation rate in the Inverdales was 1·75 times as great as the average of the other three breeds. Embryo survival to term for ewes conceiving to two, three or four ovulations averaged 0·89, 0·77 and 0·64, respectively, and was significantly different among breeds fP< 0·001). The greater ovulation rate in Inverdales than Romneys was sufficient to explain the Inverdale effect on reduced embryo survival. The highest embryo survival was observed in the Coopworth breed (P< 0·001).
Video image analysis for on-line classification of lamb carcasses
Authors: Stanford K. , Richmond R. J. , Jones S. D. M. , Robertson W. M. , Price M. A. , Gordon A. J.
Published: September 2010

Video image analysis (VIA), carcass shape and colour data were collected for 1211 lambs of known gender, breed type and carcass weight over a 1-week period using the VIAscan® system developed by the Australian Meat Research Corporation. Classification data (thickness of soft tissue over the 12th rib (GR measurement) and subjective conformation scores on a five-point scale of the leg, loin and shoulder) were assessed by an Agriculture and Agri-Food Canada grader after carcasses had chilled at 5°C for 3 to 6 h. Dissections into saleable meat yield (no. = 58) were performed after carcasses had chilled an additional 24 h. The timing of this study, which was dependent on availability of the VIA equipment, influenced the age and type of lambs available for analysis. The majority of lambs evaluated were wool-breed wethers, age > 10 months, of average GR (15·7 (s.d. 0·2) mm) and muscle conformation (3·0, s.d. 0·1). VIA improved the prediction of saleable meat yield (R2 = 0·71, residual s.d. = 14g/kg) compared with the current classification system (R2 = 0·52, residual s.d. = 18 g/kg). Although prediction ofGR measurement by VIA resulted in a large residual error (residual s.d. = 2·4 mm), the proportion of waste fat (perirenal and subcutaneous) and bone dissected from the carcass was accurately predicted (R2 = 0·62, residual s.d. = 11 g/kg). Proportions of leg (R2 = 0·71, residual s.d. = 7 g/kg) and shoulder (R2 = 0·62, residual s.d. = 9 g/kg) primals were also accurately predicted by VIA, although there were no significant predictors for the proportion of the loin (P > 0·15). VIA improved the prediction of saleable meat yield compared with the current classification system. However collection of additional data including some from extremely lean or well muscled animals would be required before VIA could be recommended to classify lamb carcasses
Response to dietary protein during lactation of Meishan synthetic, Large White and Landrace gilts given food to achieve the same target backfat level at farrowing
Authors: Sinclair A. G. , Cia M. C. , Edwards S. A. , Hoste S.
Published: September 2010

A 3 × 2 factorial experiment was used to investigate the influence of the breed type of gilts (Meishan synthetic 50% (M), purebred Large White (LW) and purebred Landrace (LR)) on response to insoenergetic diets of differing protein levels (180 g crude protein (CP) per kg, 9 g lysine per kg; or 240 g CP per kg, 12 g lysine per kg) offered to appetite over a 28-day lactation. Body fat reserves were adjusted during pregnancy by supplementing a set quantity of basal diet (131 g CP per kg, 12·7 MJ digestible energy (DE) per kg) with an energy source (maize starch + soya oil), to attain a backfat at P2 (6·5 mm off midline at last rib) of 25 mm at farrowing for all breeds. There were no significant diet effects or breed ×diet interactions on lactational performance. On day 1 of lactation, backfat was: M = 25·9, LW = 24·9, LR = 23·9 mm (P < 0·005). M gilts were lighter at farrowing (M = 173, LW = 192, LR = 182 kg; P < 0·001) and had more piglets than LW and LR. LR gilts had heavier piglets at birth (M = 1·13, LW = 1·18, LR = 1·38 kg, P < 0·001) than M and LW gilts. M gilts had a higher food intake (M = 6·4, LW = 5·2, LR = 5·1 kg/day; P < 0·001) but higher fat (M = 4·1, LW = 2·2, LR = 2·9 mm; P < 0·05) and weight (M = 15·9, LW = 1·0, LR = 4·7 kg; P < 0·001) loss over lactation than LW and LR gilts. LW gilts had a lower lactation output as reflected by lower litter weights at weaning than M and LR gilts (M = 73·7, LW = 59·3, LR = 75·2 kg; P < 0·002). It is concluded that lactation of gilts is not improved by provision of a very high protein diet (240 g CP per kg) and that performance still differs between breeds when backfat levels are standardized.
Controlling inbreeding in dairy MOET nucleus schemes
Authors: Luo Z. W. , Woolliams J. A. , Thompson R.
Published: September 2010

A nucleus dairy population using multiple ovulation and embryo transfer (MOET) was stochastically modelled with overlapping generations. The aim was to investigate the feasibility of controlling inbreeding in MOET breeding schemes using more realistic parameters for embryo recovery and best linear unbiased prediction (BLUP) for genetic evaluation. Four different cases (involving the culling of donors, more donors and the use of organized progeny testing of nucleus bulls) were studied in combination with nested and factorial designs. Further studies involved modifications of the selection index, including subtracting parental breeding values, inflating the genetic variance in the BLUP evaluation and penalizing inbred animals; these options were examined both with and without organized progeny testing. The effects of applying these schemes on both genetic response and rate of inbreeding were investigated. The results stressed the importance of incorporating progeny testing into MOET schemes for value of reducing inbreeding whilst maintaining genetic progress. There was no significant difference between nested and factorial designs. In the absence of progeny testing the inflation of genetic variance was more effective than subtracting parental breeding values at controlling inbreeding; however incorporating progeny testing made the latter strategy more potent and the superiority of inflating the genetic variance was in this case much smaller and non-significant.
The effect of the β-adrenergic agonist cimaterol on performance and carcass and meat quality in culled dairy cows
Authors: Fiems L. O. , Boucqué Ch. V. , de Brabander D. L. , Cottyn B. G.
Published: September 2010

Forty-eight culled dairy cows were assigned to one of two treatment groups to investigate the effect of a β-adrenergic agonist in mature cattle. They were finished during a 63-day period on a concentrate diet, containing 0 or 4 mg/kg cimaterol. No food was given in the 20 h prior to slaughter.

Cimaterol had no effect on food intake, but significantly improved food conversion efficiency and increased live-weight gain, carcass weight and dressing proportion (P < 0·05). Cimaterol induced muscle hypertrophy as evidenced by an improved EUROP carcass classification and a higher longissimus thoracis (LT) cross-sectional area (P < 0·001). EUROP fat score and fat content in the carcass and the LT were lowered (P < 0·05). Cimaterol resulted in brighter meat (higher L-value: 37·0v.35·6; P<0·05) with a higher shear force value (64·0v.46·4 Newton; P<0·01) compared with control animals. It seems likely that mature cattle receiving cimaterol respond similarly to younger growing animals.
Genotype with feeding regime interaction in pigs divergently selected for components of efficient lean growth rate
Authors: Cameron N. D. , Curran M. K.
Published: September 2010

The genotype with feeding regime interaction was examined by testing pigs from four selection groups on both ad libitum and restricted feeding regimes. Within each selection group, there were high, low and control lines, which had been selected for lean food conversion ratio (LFC), daily food intake (DFI) or lean growth rate on ad libitum (LGA) or on restricted (LGS) feeding, in Large White-Edinburgh (LW) and Landrace-Wye (LR) populations. There were 1187 LW pigs and 768 LR pigs in the study, with 344 LW and 133 LR pigs tested on the alternative feeding regime.

In the LW population, pigs in the high LGS line grew significantly faster than the high LGA and LFC lines with ad libitum feeding (919 v. 847 and 786 (s.e.d. 31) g/day), but had similar food conversion ratios and backfat depths. The high LGS and high DFI lines were similar for growth rate, daily food intake and food conversion ratio, but backfat depth was significantly lower in the high LGS line than in the high DFI line (12·0 v. 25·9 (s.e.d. 0·7) mm). On restricting feeding, the rankings of the selection lines for growth rate, food conversion ratio and mid-back fat depth were broadly similar to those with ad libitum feeding, except for the high LFC line. In the LR population, the high LGS, LGA and LFC lines did not differ significantly in growth rate, daily food intake, food conversion ratio and backfat depth within either the ad libitum or restricted feeding regimes. Growth rate of the high LGS line was similar to the high DFI line on ad libitum feeding (828 v. 836 (s.e.d. 40) g/day), but significantly higher on restricted feeding (704 v. 636 (s.e.d. 23) g/day). On both feeding regimes, food conversion ratio and backfat depth were significantly lower in the high LGS line compared with the high DFI line.

In the LW population, the genetic correlation between feeding regimes for growth rate was significantly less than one (0·4 (s.e. 0·20)), but was not significantly different from unity (0·8 (s.e. 0·14)) for backfat depths. Based on the performance test results, selection for lean growth with testing on a restricted feeding regime may be preferable to testing animals on an ad libitum feeding regime.
Effect of energy intake on performance, nutrient and tissue gain and protein and energy utilization in growing boars
Authors: Quiniou N. , Noblet J. , van Milgen J. , Dourmad J.-Y.
Published: September 2010

Twenty crossbred (Large Wliite × Piétrain) boars were used to investigate the effect of energy intake (0·71, 0·80, 0·90, 1·00ad libitum) and body weight (BW) on growth performance, and rates of protein (PD) and lipid (LD) deposition between 40 and 100 kg BW. Daily crude protein intake was kept constant. Total PD and LD were measured according to the comparative slaughter technique (CST) during total experiment and according to nitrogen and energy balance technique at 45, 65, 80 and 94 kg mean BW. Average daily gain increased linearly with metabolizable energy (ME) intake (+36 g/MJ ME) whereas food conversion ratio was not affected by energy level (28·0 M] ME per kg BW gain). Daily PD increased from 126 to 171 g/day, and LD from 70 to 187 glday between 0·71ad libitumandad libitumME intake. Maintenance ME requirement was constant when expressed per kg BW'60 (992 kJ/day). PD varied with ME intake above maintenance (MEp) according to a linear-plateau relationship. The slope decreased with BW (+11·5 g/MJ MEp at 65 kg BW and +9·0 g/MJ MEp at 94 kg BW). LD was linearly related to MEp (+16 g/M} MEp). The LD: PD ratio in marginal empty BW gain was constant within BW class, but increased from 1/5 to 1/9 between 65 and 94 kg BW.
Prediction of the apparent digestible energy value of fats given to pigs
Authors: Powles J. , Wiseman J. , Cole D. J. A. , Jagger S.
Published: September 2010

Data from experimental programmes designed to investigate the effect of chemical structure of fats upon their apparent digestible energy (DE) value for pigs were subjected to regression analysis. For growing pigs, over the approximate live-weight range 30 to 90 kg, 25 data points were available, with fats evaluated having a range in the ratio of unsaturated to saturated fatty acids (U/S) from 0·66 to 15·67 and in free fatty acid (FFA) content from 8 to 818 g/kg. Sixteen data points were available for young pigs of approximately 12 kg live weight with a range in U/S from 0·62 to 5·71 and in FFA content from 54 to 756 g/kg. The wide range of values for U/S and FFA content had been obtained by blending different fats and, therefore, represented both the range and extremes likely to be found in the formulation of pig diets. Derivation of prediction equations for DE were based upon a series of non-linear regression analyses employing, in sequence, U/S, U/S + FFA content and U/S × FFA content. The DE offats could be predicted from U/S and FFA content with equations accounting for 0·802 and 0·768 of the variation in DE values for growing and young pigs respectively. The most appropriate equation for pigs of all live weights employed U/S and FFA content additively (U/S + FFA content). The equation for growing pigs was DE (MJ/kg) = 36·898 – (0·0046FFA (g/kg)) — 7·33e(–0·906U/S) and for young pigs was DE (MJ/kg) = 37·890 — (0·0051FFA (g/kg)) –8·20e(–0·515U/S). Comparisons revealed that differences between the two age groups, with lower values achieved with younger pigs, -were more pronounced the lower U/S and the higher FFA content of the fat.
Growth curves of ostriches (Struthio camelus) from Oudtshoorn in South Africa
Authors: Cilliers S. C. , du Preez J. J. , Maritz J. S. , Hayes J. P.
Published: September 2010

Growth results of 43 ostrich males and females were used to compile growth parameters of a flock that is representative of Oudtshoorn birds, using the Gompertz model. Growth results comprised 19 recordings of body weight for each individual commencing from 1-day-old to day 520. Individual fits of data to the growth model were exceptionally good, resulting in low CV values of 0·02 and 0·03 for the mean values of all estimates of mature live weight for male and females respectively. The estimated mean mature body weights for the flock were 119·2 kg for males and 122·3 kg for females. Rates of maturing were 9100 and 8500 for males and females respectively which corresponded to ages of 180·83 and 199·2 days at which maximum gain in weight were achieved. None of these parameter estimates differed significantly between sexes. Results in the present study suggested substantial adjustments to growth parameters for Oudtshoorn ostriches published by du Preez, Jarvis, Capatos and de Kock, 1992.
Genetic progress and inbreeding for alternative nucleus breeding schemes for beef cattle
Authors: Villanueva B. , Simm G. , Woolliams J. A.
Published: September 2010

Alternative closed breeding schemes for beef cattle are analysed using stochastic computer simulation. Multiple ovulation and embryo transfer (MOET) schemes are compared with conventional schemes (schemes without MOET) with an equal expected number of progeny born per year. Schemes are compared for genetic gain and inbreeding obtained after 25 years of selection. The trait considered, evaluated in both sexes, has an initial heritability of 0·35. Different population sizes and numbers of sires selected are evaluated. Current realistic parameters for embryo production are assumed in MOET schemes.

After 25 years of selection, and with no control on inbreeding, cumulative genetic gains are about 50% higher in MOET schemes compared with conventional schemes. The benefit from MOET is mostly due to increased selection intensities in females. The rate of inbreeding increases by up to nearly 300% when MOET is used. This maximum percentage increase in inbreeding following the use of MOET can be reduced to about 100% when selection and mating strategies for controlling inbreeding are used. The effect of the number of sires used on the inbreeding obtained is more important than the effect of the size of the herd. In MOET schemes, increasing the number of sires selected by a factor of three, leads to reductions in inbreeding rates of 40%. When schemes of the same size are compared at similar acceptable inbreeding levels, MOET schemes give around 30% higher genetic progress than conventional schemes.
Prediction of the body composition of lambs from the composition of their non-carcass components
Authors: Wilkinson R. G. , Greenhalgh J. F. D.
Published: September 2010

Information on the chemical composition of Suffolk × Blackface lambs was collected and used to predict empty body (EB) component weights from empty body weight (EBW) and non-carcass (NC) component weights. EBW accounted proportionately for 0·94, 0·89 and 0·95 of the variation in EB crude protein, fat and energy content. A combination of NC component weights accounted proportionately for 0·94, 0·95 and 0·96 of the variation in EB crude protein, fat and energy content. EBW and a combination of NC component weights together accounted proportionately for 0·97, 0·97 and 0·98 of the variation in EB crude protein, fat and energy content. Chemical analysis of NC components is cheaper and easier than whole body analysis and provides a viable alternative to sample joint or specific gravity analysis.
The requirements of weaned piglets for a training period prior to a choice-feeding regime
Authors: Dalby J. A. , Forbes J. M. , Varley M. A. , Jagger S.
Published: September 2010

The requirement for a training period prior to a choice feeding regime was assessed using 36 weaned piglets whose initial live weight was 6·2 (s.d. 1·21) kg. Two foods (H and L) were offeredad libitumas the choice and these were similar in energy but differed in crude protein (CP) concentration (291 g/kg and 155 g/kg fresh matter respectively). The pigs ivere subjected to one of three training treatments: treatment ALTERNATE allowed piglets the two foods separately on alternate days for 6 days, followed by a free choice of the two foods; treatment THREE allowed 3 days of one food followed by 3 days of the other prior to the free choice; treatment CHOICE gave the animals free choice immediately. Piglets on a fourth treatment, CONTROL, were given a single food M (242 g CP per kg fresh food) as a control. Weight gain (0·60, 0·59, 0·59 and 0·61 (s.e. 0·005) kg/day) and food intake (0·776, 0·752, 0·771 and 0·747 (s.e. 0·010) kg/day) did not differ significantly between treatments ALTERNATE, THREE, CHOICE and CONTROL respectively in the 19-day post-training period. A significant difference was seen in the protein consumption (0·145, 0·150, 0·139 and 0·177 (s.e. 0·005) kg/day). This together with a tendency for the proportion of food H selected to decline as the growth period progressed, indicated that newly weaned piglets are capable of regulating their protein intake when offered a free choice of two foods differing in their CP concentration, without a necessity for an initial training period.
Ontogenic study of insulin-like growth factor-1 and growth hormone receptor mRNA expression in porcine liver and skeletal muscle
Authors: Brameld J. M. , Weller P. A. , Pell J. M. , Buttery P. J. , Gilmour R. S.
Published: September 2010

The growth hormone-insulin-like growth factor (GH-IGF) axis is involved in the control of postnatal growth in all animals studied to date. At birth, blood levels of IGF-1 are low, although levels of GH are high. Thus a switching occurs during the postnatal period, which involves an increase in liver GH-receptors (GHR). This study investigates the changes in serum IGF-1 and IGF-1 and GHR mRNA in liver and skeletal muscle of growing pigs. The period from birth to 20 days of age showed a gradual increase in both IGF-1 and GHR mRNA expression by the liver, thus accounting for the gradual increase in serum IGF-1. The IGF-1 mRNA expressed was found to be predominantly class 1 transcripts with very few class 2 transcripts. There was a plateau of liver IGF-1 mRNA levels after 20 days and up to 140 days, even though the expression of GHR mRNA continued to increase. The levels of expression of the two genes were found to correlate in the first 20-day period (r = 0·76,P< 0·005), but not in the later period (r = 0·44,P> 0·05).

Levels of expression of both genes in the LD muscle were highly variable, with no age related changes being observed. However, a significant negative correlation of expression of the two genes was observed (R = 0·60,P< 0·001), with the correlation still being significant in the two age periods.

The data are consistent with a likely initial dependence for postnatal growth upon GH-stimulated IGF-1 mRNA expression by the liver, up to 20 days of age. After this time, hepatic expression of IGF-1 mRNA reaches a plateau, even though the serum IGF-1 and hepatic GHR mRNA levels continue to rise. A possible explanation for this could be an increase in either turn-over or stability of IGF-1 mRNA, giving rise to increased levels of peptide with no apparent change in mRNA level. Another possibility is that an increased expression/production of the IGF-binding proteins leads to an increase in the half-life of the peptide in the circulation.
Changes in the composition of plasma very low density lipoprotein during pregnancy and lactation in genetic lines of pigs
Authors: Wright M. M. , Lean I. J. , Herrera E. , Dodds P. F.
Published: September 2010

Plasma very low density lipoproteins (VLDL) of gilts were separated into two sub fractions according to their affinity for heparin. The proportion of VLDL present as subfraction 2 (higher affinity for heparin) varied, according to the genetic line of the pigs, between 0·21 and 0·78 in virgin gilts. The proportions were related to the variation in piglet survival in the same nine genetic lines by a quadratic equation, which predicted that greater than 90% survival to weaning was to be found in piglets born to gilts having between about 0·3 and 0·7 of their VLDL as subfraction 2. This observation suggests a simple measurement that could be used in the selection of sows for a breeding programme. The proportion of subfraction 2 fell throughout pregnancy in each of three genetic lines measured and only returned to pre-pregnant values after weaning: these changes did not correlate with the changes in the lipid composition of plasma VLDL measured during pregnancy and lactation. The findings suggest a role for the VLDL subfractions in controlling the nutrition of the neonatal pig.
Relationship between puberty in heifers and the cessation of luteal activity after nutritional restriction
Authors: Vizcarra J. A. , Wettemann R. P. , Bishop D. K.
Published: September 2010

The relationship between puberty and the cessation of luteal activity after nutritional restriction was evaluated in 15 Angus × Hereford heifers. Heifers attained puberty at a body weight of 297 (s.e. 6) kg and a body condition score (BCS) of 5·5 (s.e. 0·1) on a scale of 1 (emaciated) to 9 (obese). After 154 (s.e. 16) days of nutritional restriction, heifers became anoestrus at a weight of 273 (s.e. 8) kg and a BCS of 3·0 (s.e. 0·2). The Spearman's rank correlation coefficient between date of-puberty and date of cessation of luteal activity was (r = –0·49; P < 0·06). This indicates that the heifers that attained puberty first were the last to cease luteal activity during nutritional restriction.
The effect of sward height on grazing behaviour and herbage intake of three sizes of Charolais cattle grazing cocksfoot (Dactylis glomerata) swards
Authors: Cazcarra R. Ferrer , Petit M. , D'hour P.
Published: September 2010

Mature non-lactating cows, 18-month-old heifersand7-month-oldfemale calves of the Charolais breed (eight animals of each age) were strip-grazedon short (S, sward surface height: 7·5 cm), medium (M,10·2 cm) and tall (T, 21·1 cm) cocksfoot (Dactylis glomerata) swards at a daily herbage allowance of 40 g dry matter per kg live weight over three 15-day experimental periods. The swards were leafy regrowths of 1 (S), 2 (M)and 3·5 (T)weeks of age. Herbage intake was estimated by the n-alkane method, and grazing behaviour was recorded visually.

Intakes per kg live weight of calves and heifers were higher than those of cows on all swards(P < 0·01). Calves tended to maintain intake, whereas cows and heifers reduced their intake as sward height decreased. Bite weight decreased linearly with sward height, this decrease being greater for larger animals (P < 0·001). As sward height decreased, the scaling factor of bite weight to live weight decreased. Biting rates increased as sward height decreased (P < 0·001) and were lower in calves than in older cattle (P < 0·001). Calves had lower intake rates per kg live weight than cows in T swards, and the reverse was true in S swards (P < 0·001). Younger cattle always grazed longer than cows, but differences were reduced as sward height decreased (P < 0·01). Cows and heifers wereunable to increase their grazing time sufficiently to compensate for lower intake rates in S and M swards, resulting in reduced herbage intakes. Faecal markers and grazing behaviour suggested a greater selectivity by calves compared with older cattle.
The effects on milk yield and composition of incorporating lactose into the diet of dairy cows given protected fat
Authors: Garnsworthy P. C.
Published: September 2010

Twenty-eight Holstein/Friesian dairy cows were divided into four groups of seven. From weeks 4 to 15 of lactation they were given a basal diet consisting of 8 kg hay, 2 kg sugar-beet feed and 2 kg grass nuts, together with a concentrate allowance of 8 kg/day. Concentrates for group A were based on cereals and soya (control). Concentrate B contained 60 g protected fat supplement per kg; concentrate C contained 100 g lactose per kg; concentrate D contained 60 g fat supplement and 100 g lactose per kg. Milk yields were 24·6, 27·7, 25·6 and 26·5 kg/day and milk protein concentrations were 32·3, 30·7, 32·7 and 31·9 g/kg for groups A, B, C and D respectively. The effect of fat supplementation on milk yield and protein concentration was significant (P < 0·05) but the effect of lactose was not significant. Milk fat concentration was not significantly affected by treatment. It is concluded that lactose can partially alleviate the depression in milk protein concentration often observed when cows are given protected fat.