Data from the F2 generation of a Large White (LW) ✕ Meishan (MS) crossbred population were analysed to detect quantitative trait loci (QTL) for leg and gait scores, osteochondrosis and physis scores. Legs, feet and gait score were assessed in 308 F2 animals at 85 ( + 5) kg and osteochondrosis and physis scores were recorded for the right foreleg after slaughter. A genome scan was performed using 111 genetic markers chosen to span the genome that were genotyped on the F2 animals and their F1 parents and purebred grandparents. A QTL on chromosome 1 affecting gait score was significant at the genome-wide significance level. Additional QTL significant at the chromosome-wide 5% threshold level (approx. equivalent to the genome-wide suggestive level) were detected on chromosome 1 for front feet and back legs scores, on chromosome 13 for front legs and front feet scores, on chromosome 14 for front legs, front feet and back legs scores and on chromosome 15 for back feet score. None of the QTL for osteochondrosis score exceeded the chromosome-wide suggestive level, but one chromosome-wide QTL for physis score was found on chromosome 7. On chromosome 1, gait and front feet scores mapped to the middle of the chromosome and showed additive effects in favour of the LW alleles and no dominance effects. The QTL for back legs score mapped to the distal end of the chromosome and showed a dominant effect and no additive effect. On chromosomes 14 and 15, the LW allele was again superior to the MS allele. On chromosome 13, there were both additive and dominance effects in favour of the MS allele. The MS alleles on chromosome 13 may have potential for introgression into a commercial LW population. The other putative QTLs identified may have value in marker-assisted selection in LW or MS-synthetic populations.

Genetic variation in host resistance to nematode infection was studied in two calf crops of Angus cattle under natural pasture challenge conditions in New Zealand, using faecal egg count (FEC) as a marker trait. Genetic and phenotypic correlations of FEC with anti-nematode antibody (Ab) level and live weights were also estimated. Ab to the third larval stages of Cooperia curticei (Cc), Cooperia oncophora (Co), Ostertagia ostertagi (Oo) and Trichostrongylus colubriformis (Tc) were assayed, along with Ab to the adult stages of Co and Oo. Calves were born in the late winter/early spring of 1995 and 1996 over a 7-week period each year; they were weaned at an average of 4 months of age, and faecal samples for FEC were taken at 10 months of age (1995 crop) and at 7 months of age (1996 crop). Blood samples for Ab were taken from both calf crops at intervals between 4 and 20 months of age, and later in peri-partum heifers and cows (23 to 25, and 36 to 37 months of age). For the two calf crops combined, there were 370 animals by 24 sires. Additional blood samples were taken on related animals from the 1993 and 1994 calf crops (218 extra animals, 19 different extra sires). The heritability of loge (FEC + 100) was 0•32 (s.e. 0•16), and heritabilities of loge Ab between 4 and 9 months of age averaged 0•30, between 11 and 20 months of age 0•22, and peri-partum 0•30. Between-animal repeatabilities of Ab levels from samples taken between 4 and 9 months of age averaged 0•40, between 11 and 20 months 0•48, and peri-partum 0•35. Genetic and phenotypic correlations among loge Abs for various nematode species (in hosts aged 4 to 9 months) averaged 0•82 and 0•61, respectively. The corresponding genetic and phenotypic correlations between loge Ab and loge(FEC + 100) averaged –0•48 and –0•07, respectively, whilst those between loge Ab and yearling weight averaged 0•29 and 0•13, respectively. It was concluded that direct selection to reduce FEC should be feasible if required, but index selection combining increased live weight and reduced FEC would often be preferable; anti-nematode Ab levels were repeatable, and FEC and Ab levels were negatively associated genetically.

The sensitivity to dietary lysine: energy content of pigs from lines divergently selected over seven generations for components of efficient lean growth rate was quantified by the within-selection line regression of performance test traits on diet class. Large White pigs were performance tested over three 14-day test-periods starting at 30, 50 and 75 kg and offered, to appetite, isoenergetic diets differing in dietary total lysine: energy (0•59, 0•69, 0•81, 0•91, 1•01, 1•12 and 1•23 g/MJ digestible energy (DE)). Within each litter, full-sibs were performance tested on different diets. Pigs were also performance tested on a diet-choice procedure using diets with total lysine: energy of 0•69 and 1•12 g/MJ DE to determine the correlation between performance on phase-feeding and diet-choice.

The study consisted of 578 animals with 459 pigs tested with phase-feeding and 119 tested on diet-choice procedures. The study detected significant selection line and dietary effects on performance test traits, but no significant between-selection line differences in sensitivity to dietary total lysine: energy. When combinations of performance test traits were transformed into predicted lysine and energy utilization traits there were significant selection line effects on predicted nutrient allocation, but not in responses to increasing dietary total lysine: energy. The lack of between-selection line differences in sensitivity to dietary total lysine: energy indicated that the consequences of changing dietary total lysine: energy will be broadly similar across a range of genotypes, as spanned by the selection lines of the study.

Genetic correlations between performance traits of phase-fed and diet-choice pigs suggested that predictions of genetic merit will be similar with animals tested on either procedure between 30 and 75 kg but post 75 kg predicted genetic merit for growth rate and lysine intake should be estimated separately for performance on diet-choice or for performance on a given diet. In contrast, predicted genetic merit for fat deposition with performance testing on diet-choice will be highly correlated with predicted genetic merit with testing on a single diet.

Thirty cull Scottish Blackface ewes were scanned three times over a period of 1 week using X-ray computed tomography (CT). Cross-sectional CT reference scans were taken at seven anatomical sites per ewe: ischium (ISC), femur (FEM), hip (HIP), 5th lumbar vertebra (LV5), 2nd lumbar vertebra (LV2), 8th thoracic vertebra (TV8) and 6th thoracic vertebra (TV6). Ewes were then slaughtered and dissection measurements collected.

Results of multiple regression analyses suggested that five reference scans allow accurate prediction of total weights of bone, muscle and fat (carcass and internal). The most informative cross-sectional scans were ISC, HIP, LV5, LV2 and TV8, from which prediction equations were derived. Fat and muscle weights were predicted accurately (R2 = 80 to 99%) but bone weight was predicted less accurately (R2 = 56%). Repeatabilities were high for the CT measurements used to predict fat and muscle (0•82 to 0•99) but lower for those used to predict bone (0•19 to 0• 86).

Classification of pig carcasses in the European Community is based on the lean meat percentage of the carcass. The lean meat percentage is predicted from instrumental carcass measurements, such as fat and muscle depth measurements, obtained in the slaughter-line. The prediction formula employed is derived from the data of a dissection experiment and has to meet requirements for authorization as put down in EC regulations. Requirements involve the sampling procedure and sample size for the dissected carcasses and the accuracy of prediction. Formulae are often derived by linear regression. In this paper we look at a particular type of sampling scheme. This involves selection of carcasses on the basis of carcass measurements not all of which are intended to be used as prediction variables. This sampling scheme frequently appears in requests for authorization of carcass measurement instruments and accompanying prediction formulae, despite the fact that it lacks formal statistical justification when used in conjunction with linear regression. The objective of this work was to assess the performance of the prediction formula that follows from this potentially faulty combination of sampling scheme and linear regression in relation to the requirements in the EC regulations. We show that this sampling scheme may produce poor predictions for lean meat percentage compared with proper sampling procedures with selection on prediction variables only or random sampling. We do so by computer simulation. Initially, simulated data were based on recent and historic data from The Netherlands. Prediction variables are fat and muscle depth measurements. The additional variable involved in sampling, but not included in the regression, was carcass weight. We also show that due to this faulty sampling scheme there is a serious risk that a new measurement instrument may not be authorized because performance criteria in the EC-regulations are not met.

Tissue depletion and repletion were investigated in 142 Scottish Blackface ewes using computed tomography (CT). Ewes of two ages (2 or 3 years) and differing reproductive status (barren, single- or twin-bearing) were studied through one annual production cycle to investigate mobilization of carcass fat (subcutaneous and inter-muscular), internal fat and muscle.

Ewes were CT scanned five times during the 1-year study period: pre-mating; pre-lambing; mid-lactation; weaning; pre-mating the following year. For each animal at each of the five scanning events cross-sectional CT scans were taken at five anatomical sites (ischium, hip, 5th lumbar vertebra, 2nd lumbar vertebra and 8th thoracic vertebra). CT images were analysed to yield areas of carcass fat, muscle and internal fat and total weights of these tissues were estimated at each scanning event using prediction equations derived from a separate calibration data set.

The results show that both carcass and internal fat depots were depleted during pregnancy and early lactation and repleted from mid-lactation to mating the following year. In proportionate terms, internal fat was most labile, but carcass fat contributed more to total weight change because it was a bigger fat depot. Subcutaneous fat was the largest and most labile of the carcass fat depots. Muscle reserves were depleted only when fat reserves had fallen to very low levels. Older ewes carried more carcass fat in total than younger ewes when reserves were low. Mobilization of tissue reserves in twin-bearing ewes was less than in single-bearing ewes, probably due to preferential feeding.

Leptin has an important rôle in the control of appetite and energy expenditure. Several studies have reported the effects of leptin in ruminants. However, little is known about changes in circulating leptin concentrations in neonates of ruminant species, or the effects of weaning on plasma leptin concentrations. The main objectives of this experiment were: to examine plasma leptin concentrations in lambs, in the period from just after birth through to weaning; to examine the effect of weaning on plasma leptin concentrations, and to compare leptin concentrations measured using a ‘multi-species’ leptin radio-immunoassay (RIA) kit and a specific ovine RIA in lambs during the 6-month period after weaning. In a previous paper, we reported leptin concentrations using a commercial RIA during the post-weaning period. However, we were not able to measure plasma leptin concentrations from just after birth to weaning as they were apparently below the level of sensitivity of the assay. In the present study, five crossbred lambs were removed from their dams within 2 days after birth, and bottle-fed on milk replacer at a level sufficient to meet a 1•2 times maintenance metabolizable energy intake. Lambs were weaned 45 days after birth, and housed individually in pens. The lambs were offered timothy hay, rolled barley and soya-bean meal to meet a 200 g daily gain during the post-weaning period. During the pre-weaning period, blood samples were collected within 5 h of birth and thereafter at 09:00 h; every day from 2 to 6 days of age; at 2-day intervals from 6 to 14 days of age; and at 3-day intervals from 14 to 45 days of age. During the post-weaning period, blood samples were collected before and 3 and 6 h after the morning meal at the ages of 0•5, 1, 2, 3, 4, 5 and 6 months. Plasma leptin concentrations slightly increased (P < 0•05) just after birth and then remained constant until 45 days old (P > 0•05). Additionally, plasma leptin concentration was not significantly changed following weaning. During the post-weaning period, plasma leptin concentrations were compared using two RIA systems. The correlation between plasma leptin concentrations measured by the ‘multi-species’ leptin RIA kit and specific ovine RIA was poor (r = 0•41). These findings are consistent with other reports and suggest that the ‘multi-species’ leptin RIA kit is not suitable for estimating leptin plasma concentrations in ruminants.

In the double-muscled (DM) Belgian Blue beef (BBB) breed, caesarean section (CS) is being applied systematically as a management tool to prevent dystocia. As a matter of fact, CS is the only possible way of calving in the breed. High birth weight and a relatively small pelvic area are the main causes of dystocia and, in the DM-BBB breed, the reasons for the systematically applied CS. Selection for lower birth weight and larger pelvic sizes might reduce dystocia and routine CS. Few data on inner pelvic sizes of pedigree animals are available. Using external measurements to estimate the inner pelvic sizes might be an option to resolve this problem. In this study, animals of the DM-BBB breed were measured and weighed on farms and in abattoirs. External and internal pelvic sizes increased with live weight and age of the animals. Gender had a significant influence on inner pelvic traits. Increased muscular conformation was associated with decreased inner pelvic dimensions. Models with weight, gender, age, withers height and outer pelvic width (TcTc) can be used to estimate inner pelvic sizes (R2 between 0•35 and 0•77). The estimated inner pelvic sizes can then be used to genetically evaluate pelvic traits in the DM-BBB breed. Improving weight, withers height and TcTc width in combination with lowering muscular conformation may help to decrease the high rate of caesarean section in the DM-BBB.

This experiment investigated the effect of feeding grass silage alone or supplemented with additional energy and/or protein on the partitioning of nutrients between fat and lean deposition in cattle grown from approximately 140 to 550 kg. The distribution of total body fat between the main fat depots was also assessed. Ninety-two Hereford ✕ Friesian steers (140±18•8 kg initial live weight) were allocated to one of four dietary treatments; grass silage offered either alone (diet S) or supplemented with fish meal (diet FM; 150 g/kg silage dry matter (DM) intake but offered at equal estimated metabolizable energy (ME) intake to silage) or forage-concentrate diets of silage and a barley/soya (80: 20) concentrate at ratios of 70: 30 or 30: 70 on a DM basis (diets 30C and 70C, respectively). Eight animals were slaughtered at the start of the trial to determine initial carcass composition. Of the remaining 21 animals per diet, three were slaughtered at each of seven live weights ranging between 250 and 550 kg, at 50-kg intervals. Animals were given food individually and diets were offered ad libitum (except for FM) along with 100 g/day of a commercial vitamin/mineral pre-mix. At slaughter, half carcasses were minced for the determination of fat and protein content and visceral fat depots, perirenal, mesenteric and omental were removed and weighed. The relationships between chemical composition and empty body weight (EBW) at slaughter were assessed using allometric equations (loge y = loge a + b loge EBW). The composition of the silage was 271•9 g/kg toluene DM with a total nitrogen and estimated ME of 26•5 g/kg DM and 11•8 MJ/kg DM, respectively. DM intakes increased (P < 0•001) with increasing level of concentrate and this generated the expected differences in both energy and protein intake. Live-weight gains increased by proportionately about 0•1, 0•18 and 0•34 on the FM, 30C and 70C treatments, respectively, compared with the S alone. Carcass protein deposition (kg) was relatively linear across the slaughter weights 250 to 550 kg, except for the 70C treatment where the slope (shape or curvature parameter, b) was lower compared with S (P = 0•007). Carcass fat (kg) was similar between S and FM. However, at 350 kg EBW and above, the carcasses of animals given concentrate contained more fat (P < 0•01) compared with those on silage. Carcass fat deposition (kg) showed significant curvature between 200 and 500 EBW (kg) and this was most pronounced for the concentrate treatments with the slopes of the 30C and 70C (P = 0•072, P = 0•003 respectively) differing from the silage. Similar responses were observed for the visceral fat depots. Feeding concentrates resulted in a lower proportion of the total fat being deposited as carcass fat (and hence more as non-carcass fat), proportions averaging 0•65 and 0•61 for S and 70C, respectively; P = 0•066). The proportion of mesenteric fat decreased substantially with increasing total fat (P < 0•001). The relative contribution of intramuscular fat (g/kg total fat) in the longissimus dorsi muscle increased with total fat (P = 0•007) and this was particularly apparent for the S, FM and 30C and less so for 70C. It is concluded that good quality grass silage will support high levels of performance without the need for additional concentrate supplementation. The latter may contribute towards increased fat deposition within the animal.

The objective of this study was to determine if weight and age at weaning affect the response of pigs to inclusion of cooked cereal in their post-weaning diet. In experiment 1, pigs (no. = 116) weaned at 17 to 28 days of age and weighing between 4 and 10 kg were individually given for 28 days post weaning, diets based on: (1) uncooked cereal or (2) cooked cereal (steamed and flaked wheat and maize). The gelatinized starch proportion was 0•265, 0•838, 0•203 and 0•745 for uncooked maize, steam flaked maize, uncooked wheat and steam flaked wheat, respectively. Pigs were offered 2•5 kg of starter diet (16•1 MJ digestible energy (DE) per kg and 17•4 g/kg of lysine). This was followed in each case by link diet (15•2 MJ DE per kg and 16•2 g/kg of lysine) to 28 days post weaning. Thereafter, pigs were grouped and given a common weaner diet and a common finisher diet to slaughter. In experiment 2, pigs (no. = 408) were weaned at between 20 and 28 days of age. Pigs were allocated by weight to heavy (7 to 8 kg), medium (6 to 7 kg) and light (5 to 6 kg) groups (24 groups of 17 pigs) and assigned to treatments as in experiment 1 for 26 days. A common weaner diet was offered between day 26 and day 56. In experiment 1, pig weight, food intake, daily gain, food conversion efficiency and carcass measurements were not affected by cooking (P > 0•05). Regression analysis indicated that weight and age at weaning had a significant association with weight at 28 days post weaning for uncooked (R2 = 0•628; P < 0•001) and cooked (R2 = 0•579; P < 0•001) cereal diets. In experiment 2, there was no interaction between weaning weight and cooking (P > 0•05) and no performance benefit resulted from cooking (P > 0•05). In conclusion, steam flaking did not improve pig performance during the treatment period or at any subsequent period.

The objective of this study was to assess the effect of feeding steam flaked wheat and maize in diets with high and low levels of dairy products and to examine the effect of sequence of feeding the processed cereals in diets for newly weaned pigs. In experiment 1, 96 pigs were weaned at 27 days of age, blocked on sex and weight and assigned as individually penned pigs to four dietary treatments as follows: (a) high dairy product diet (6 kg of starter diet containing 230 g/kg milk powder followed by a link diet containing 125 g/kg milk powder to 26 days) with uncooked cereal (HDP), (b) high dairy product diet with steam flaked cereal (HDPC), (c) low dairy product diet (6 kg of starter diet containing 125 g/kg milk powder followed by a link diet containing no milk powder to 26 days) with uncooked cereal (LDP) and (d) low dairy product diet with steam flaked cereal (LDPC). In experiment 2, 96 pigs were weaned at 19 to 24 days of age, blocked on sex and weight and assigned as individually penned pigs to four dietary treatments containing: (a) uncooked cereal for 26 days, (b) uncooked cereal for 14 days followed by cooked cereal to 26 days post weaning, (c) cooked cereal for 26 days and (d) cooked cereal for 14 days followed by uncooked cereal to 26 days post weaning. Steaming and flaking of wheat and maize did not significantly affect pig performance during the experimental period or at any subsequent period up to slaughter. Daily gain from day 0 to 26 post weaning was 415 and 453 g/day (s.e.13•5; P < 0•05) for low and high dairy product diets, respectively. Food conversion efficiency (FCE) from day 0 to 14 post weaning on the low and high dairy product diets was 1•86 and 1•33 g/g (s.e. 0•14; P < 0•05), respectively. Pigs given the high dairy product diets during the experimental post-weaning period reached final carcass weight 5 days earlier than pigs given the low dairy product post-weaning diets (P < 0•05). In experiment 2, treatment did not affect food intake (mean = 450 s.e. 13•2 g; P > 0•05), daily gain (mean = 382 s.e. 12•5 g; P > 0•05) or FCE (mean = 1•19 s.e. 0•02 g/g; P > 0•05). In conclusion, feeding steamed flaked wheat and maize in post-weaning diets failed to improve pig performance irrespective of dairy product or sequence of feeding cooked cereals.

The stomach and small intestine manifest a myoelectric activity pattern called the migrating myoelectric complex (MMC), which is controlled by both environmental and intrinsic factors. The daily MMC pattern has been little investigated, therefore the purpose of the present study was to study it, in weaned pigs given food twice a day. A wireless telemetric recording system was used for 24-h electromyography of the antrum and duodenum. The activity of the antrum showed little change if any, whereas the myoelectric activity of the duodenum significantly changed with respect to the time of day and feeding in conscious pigs. Namely, there were more frequent and regular MMC cycles occurring in the duodenum at night as compared with that during daytime. This change was due to the shortening of phase II of the MMC cycles that were registered at night. Phase I of the MMC showed transient variability in relation to feeding with no impact on the day/night differences. Phase III of the duodenal MMC cycle as well as the ‘feeding pattern’ did not change along with the time of day and feeding regime. In conclusion, daily variation in the duodenum may provide different conditions for digestive processes in the day and night.

New Zealand × Californian rabbit does were offered ad libitum three diets: diet A, with 960 g lucerne per kg dry matter (DM), having 8•7 MJ digestible energy (DE) and 108 g digestible protein (DP) per kg DM; diet AF with 920 g lucerne and 50 g animal fat per kg DM, having 9•6 MJ DE and 105 g DP per kg DM; and diet C, as a control diet having 12•0 MJ DE and 122 g DP per kg DM. Productive parameters were measured for the first five parities, and food intake and milk yield during the first two parities.

In experiment 1, 79 does (342 parities) were housed in a cooled building, litters were standardized to eight kits and weaned at 28 days of age. DM intake during lactation was lower (P < 0•001) but DE intake, milk yield and litter growth were higher for group C. Values for does on diet AF generally were between those of groups A and C. Average results for groups A, AF and C were respectively: 59, 65 and 51 days for the parturition interval; 160, 170 and 193 g for daily milk output in the first two lactations; 3•7, 4•0 and 4•5 kg for litter weight at weaning.

In experiment 2, 64 does (294 parities) were housed in a climatic chamber at a constant temperature of 30oC, litters were standardized to six kits and weaned at 35 days of age. DM intake during lactation was lower (P < 0•001) but milk yield and litter growth were higher (P < 0•001) for C does. Average results for groups A, AF and C were respectively: 70, 70 and 56 days for parturition interval; 106, 128 and 128 g for daily milk output in the first two lactations; 3•7, 4•4 and 4•4 kg for litter weight at weaning. Lucerne-based diets allowed a reasonable performance of reproductive rabbit does in the long term, even under hot conditions.

The objective of the study was to evaluate the effect on reproductive performance of varying level of concentrate supplementation with both high and medium genetic merit cows in a spring calving grass-based system of milk production. The effect of year, cow genetic merit for milk production and concentrate feeding level on milk production, body condition score, live weight, blood metabolites and dry-matter (DM) intake were studied. A repeated measures model with a factorial arrangement of genetic merit and concentrate feeding level was used to do this. Associations between these variables and pregnancy to first service (PREG1), pregnancy to first and second service (PREG12) and overall pregnancy (PREG) rates were assessed using logistic regressions for year 2.

Cows were grouped into high (HM) and medium (MM) genetic merit based on their pedigree indices for milk production (PD milk). The HM cows had a PD milk of + 276 (s.d. 100) kg, while the MM cows had mean PD milk of + 81 (s.d. 95) kg. Within genetic merit groupings, cows were assigned to one of three concentrate feeding levels; low (LC), 376 kg; medium (MC), 810 kg; and high (HC), 1540 kg of concentrate per cow per lactation. In year 1, all 78 cows were second lactation animals, while in year 2, 71 cows (previously in year 1) were third lactation and 12 second lactation. All cows calved between February and April, and were presented for rebreeding from late April until late July each year.

When treatment means were compared, genotype and concentrate feeding levels had no significant effects on reproductive performance while year was significant for most parameters. Comparing year 2 to year 1 pregnancy rate to first service (P 0•001; 37 v. 64%), pregnancy rate to first and second service (P < 0•05; 64 v. 81%), overall pregnancy rate (P < 0•05; 78 v. 92%) were lower. Also in year 2, cows had significantly higher milk yields at first insemination (36•9 v. 32•3 kg per cow per day), greater live-weight losses from calving to first insemination (-86 v. –53 kg per cow), lower live-weight gain in the 90 days after their first insemination (+ 24•6 v. + 34•2 kg per cow), higher DM intake (20•6 v. 17•3 kg DM per cow per day) and lower plasma glucose concentrations (3•18 v. 3•61 mmol/l) than in year 1.

In year 2, there were significant negative associations between the likelihood of PREG12 and both PD milk and live-weight gain in the 90 days after first insemination. The results of this study indicate that continued selection for increased milk production, resulting in greater partitioning of energy to milk production rather than body reserves will reduce reproductive performance and offering higher levels of concentrate supplementation may not alleviate this problem.

The effect of carbohydrate supplementation on rumen utilization of ammonia-treated straw was studied in four rumen-cannulated ewes (42•0 (s.e. 2•80) kg live weight) in a Latin-square design. Diets were a 50: 50 mixture of ammoniated barley straw and a concentrate made up with different ratios of barley grain and citrus pulp, namely M1 (100: 0), M2 (66: 33), M3 (33: 66) and M4 (0: 100). Concentrates also included soya-bean meal and urea to make diets isonitrogenous. Diets were given in one meal in the morning at 0•8 kg/day. There were no significant differences among treatments in daily weighted means of rumen pH and concentration of volatile fatty acids. Acetate, propionate and butyrate molar proportions were not different among treatments, but proportions of isobutyrate (P < 0•05) and isovalerate (P < 0•10) were higher for M1 and M2. Ammonia concentration immediately before feeding was lower (P < 0•05) for M3 and M4 (72•1 and 51•3 mg/l) than for M1 and M2 (97•0 and 107•9 mg/ l). Total rumen bacterial concentration was higher (P < 0•05) with the highest barley proportion, whereas enzymatic activity against structural carbohydrates of particle-associated bacteria did not differ significantly among treatments. Digestibility of neutral-detergent fibre increased (P < 0•05) with the increase in the proportion of citrus pulp in the concentrate (0•647, 0•674, 0•684 and 0•693 for M1, M2, M3 and M4; s.e. = 0•0086). Urinary excretion of purine derivatives decreased linearly (P < 0•05) as the proportion of citrus pulp in the diet increased, while faecal excretion of purine bases was not significantly affected by dietary treatments.

A 5 ✕ 5 Latin square was conducted with ruminally and duodenally cannulated Dohne Merino wethers consuming wheat straw to determine the effect of different rumen degradable protein (RDP) levels on forage intake, fermentation characteristics, nutrient flow and digestion. The wethers had ad libitum access to water and wheat straw (32 g crude protein (CP) per kg dry matter (DM); 742 g neutral-detergent fibre (NDF) per kg DM) that was offered twice daily, immediately after intraruminal infusion of the supplements at 07:00 and 19:00 h. The supplemental RDP (calcium caseinate; 900 g CP per kg DM) levels were: 0, 40, 80, 120 and 160 g/day. Each period consisted of 14 days of adaptation and 6 days of sampling. Forage and total organic matter (OM) intakes increased in a linear manner (P < 0•01) with increasing supplemental RDP levels. Digestible organic matter intake (DOMI) displayed a quadratic increase with elevated amounts of RDP (P < 0•01). The effects of treatments on rumen and total tract digestion, as well as fluid dilution rate were minimal. Microbial nitrogen (MN) flow to the duodenum and microbial efficiency increased quadratically (P < 0•04) with increased RDP supplementation. Rumen ammonia nitrogen (NH3-N) concentrations increased linearly (P < 0•01) and total volatile fatty acids (VFA) tended to increase linearly (P = 0•07). In conclusion, RDP supplementation to Dohne Merino wethers consuming wheat straw generally enhanced rumen fermentation and forage intake. A total RDP intake (sources: calcium caseinate and wheat straw) of 3•30 g/kg M0•75 or 0•12 of DOM maximized DOMI.

In order to develop a behavioural test as well as gain information about behavioural response to novel food, we performed four experiments with cattle kept in tie-stalls and observed the behaviour (approach/avoidance, self-grooming and consummatory behaviour) for 10 (experiment 3 and 4) or 30 (experiment 1 and 2) min after provision of novel food.

In experiment 1, the effects of the novelty of the feeding method were tested using nine heifers provided with 2 kg of their usual food from the usual fodder truck or from a basket made of plastic. The novel feeding method induced increased sniffing, decreased duration of eating and increased self-grooming.

The effects of the degree of novelty of a food were examined in experiment 2 using heifers (no. = 8 to 12) and three concentrations of fish oil (1•5, 6 or 24 g/kg) and eucalyptus oil (5, 20 or 80 drops per kg) added to the usual food. Increasing the concentration of eucalyptus oil in the food led to changes in behaviour, while the addition of fish oil led to a less clear response. However, both suggested that the behaviour reflected the degree of novelty in the food. Behavioural responses to two novel foods (4 kg carrots v. 80 drops per kg of eucalyptus oil added to the usual food) as well as individual characteristics and repeatability within 72 h were examined in experiment 3. The behavioural responses to the novel foods differed, showing a higher level of approach and attempts to eat the carrots, and responses to the two different novel foods were not correlated. At the second provision, the acceptability of the carrots was greater, however responses to carrots showed an acceptable repeatability.

Finally, the cardiac (heart rate) and behavioural responses to usual food and novel food (4 kg carrots) were compared in experiment 4. Provision of novel food led to behavioural signs of motivational conflict and neophobia while the heart rate tended to be lower than when the cows were provided with usual food.

These results provide evidence that behavioural responses to novel food in cattle include signs of motivational conflict between eating motivation and neophobia, reflecting the degree of novelty in the test situation including the feeding method. However, palatability of the food might also affect the responses, and the data on heart rate suggest that novel food is not a fear-inducing stimulus.

The objectives of this study were (1) to estimate herbage intake in spring and late summer in Danish Friesian steers during their first grazing season on ryegrass/white clover pasture and (2) to investigate the effect of different winter feeding levels on subsequent herbage intake in Danish Friesian steers weighing more than 450 kg. In experiment 1, herbage intake was estimated in 18 to 20 steers with a mean live weight of 210 kg (s.e. 8•0 kg) and 312 (s.e. 8•9) kg in May/June and August respectively. In experiment 2, 22 steers were allocated to two feeding treatments in their second winter with expected daily live-weight gain of 500 g (LOW) and 800 g (HIGH). The steers weighed 440 (s.e. 15•8) kg (LOW) and 531 (s.e. 9•2) kg (HIGH) at the time of turn-out on to a ryegrass/white clover pasture. Herbage intakes were estimated in June using, as in experiment 1, the alkane bolus technique. Faeces and herbage samples were analysed for alkanes to estimate herbage intake, digestibility and botanical composition of intake. The weight gains (kg/day) were 1•156 (s.e. 0•69) and 1•054 (s.e. 0•87) in May/June and August respectively (experiment 1) and 1•592 (s.e. 0•137) and 1•273 (s.e. 0•116) in June in LOW and HIGH respectively (experiment 2). Daily herbage intake (kg dry matter (DM) per steer) estimated by alkanes C32 /C33 were 5•2 (s.e. 0•26), 9•4 (s.e. 0•28) in May/June and August (experiment 1) (P < 0•001) and 12•0 (s.e. 0•50) and 10•4 (s.e. 0•41) in LOW and HIGH (experiment 2) (P < 0•05) respectively. The diet of steers contained primarily ryegrass leaves (0•70 to 0•90) and ryegrass stems (0•10 to 0•30) and clover (0 to 0•02 and 0•18 in experiment 1 and experiment 2 respectively). It was concluded that (1) steers during their first grazing season can maintain herbage intake per kg live weight during the grazing season from May to August, and (2) steers weighing more than 450 kg are able to increase herbage intake along with compensatory growth.