1. Pellets of Cr2O3-paper were administered to sheep to reveal the excretion pattern of Cr2O3 in the faeces.

2. Two sheep fed on long hay and pelleted hay for each of two 28-day periods were given a Cr2O3-paper pellet daily at 9 00 hrs. during the 15th to the 24th day inclusive in each period.

3. Total faeces were collected at hourly intervals during the 15th to the 28th day. Dry weight and concentration of Cr2O3 of each fraction was determined.

4. A balance between input and output of Cr2O3 and a minimal standard J deviation of the concentration of Cr2O3 in the faeces between hourly collections was reached in 3 days with long hay and in 2 days when the hay was given as pellets.

5. The decline in the concentration of Cr2O3 in the faeces started the day after the administration of pellets was discontinued.

6. Grinding and pelleting of the hay resulted in a doubling of the standard deviations of the concentration of Cr2O3 in the hourly faeces collections during the period of input-output equilibrium.

7. A pattern of a diurnal cyclic trend was apparent in the concentration of Cr2O3 in the hourly faeces collections, but it varied between animals and between diets.

8. Pellets of Cr2O3-paper are suggested to facilitate the administration of Cr2O3 to ruminants.

9. The effect of sampling frequency and animal replication on estimation accuracy is discussed.

1. An anatomical explanation of the observed differences between double-muscled and phenotypically normal cattle was sought by detailed dissection of the sides of six double-muscled Santa Gertrudis steers and six Brangus steers.

2. Relative to carcass weight the double-muscled steers had a significantly greater proportion of muscle and a significantly lower proportion of bone and fat than the Brangus steers. Relative to muscle plus bone weight the muscle proportion was greater and the bone proportion lower in the double-muscled steers.

3. The musculature of the double-muscled steers exhibited a gradient of hypertrophy: 12 muscles (234g/kg of total muscle weight) were grossly hypertrophied, 56 muscles (565g/kg) were hypertrophied to a lesser degree and 28 muscles (195g/kg) showed either a minor degree of hypertrophy or no hypertrophy.

4. The grossly hypertrophied muscles were generally the larger, superficial muscles of the proximal pelvic limb and shoulder area. The muscles showing least hypertrophy were mostly small muscles located in the deeper areas of the carcass, particularly around the spine and in the proximal hindlimb, and in the proximal and distal forelimb.

5. Abnormalities of shape in double-muscled cattle may be attributed largely to altered proportions of total muscle and total fat, and to changes in weight distribution within the musculature.

The carcass characteristics of young adult female pigs (gilts) slaughtered after weaning their first litters have been investigated using three groups of 19 Landrace × (Landrace×Large White) gilts. In two treatment groups gilts were mated at their pubertal oestrus and suckled their piglets for 5 to 11 and 35 to 42 days respectively. These gilts were slaughtered on average 10 days after weaning. A third control group consisted of unmated gilts slaughtered at 118 kg live weight.

There was no significant difference in the killing-out percentage for the three groups. The carcasses of the gilts which farrowed contained significantly less fat (P<0·001) than those of the unmated controls. The carcasses of the farrowed gilts had significantly lighter middle sections (P<0·001) and significantly heavier shoulders (P<0·001) than the controls.

Despite the variations in tissue yield and distribution, the yield of prime joints for the gilts which had farrowed was only 0·62 percentage units less than that of the controls.

No commercially significant variations between groups in meat quality were observed.

The effect of two dietary electrolyte balance (dEB, Na+ + K+ – Cl-) levels (–135 and 145 mEq/kg diet) on heat production, energy and nitrogen retention in piglets was assessed. The experiment consisted of a 13-day adaptation period and a 7-day balance period in two open-circuit climate respiration chambers. Nine groups of three (4 weeks old) crossbred barrows were assigned to one of two diets (five and four groups for –135 and 145 mEq/kg dEB diets respectively). During the balance period, diets were provided at 2·3 times the energy requirement for maintenance in two equal meals daily. Total heat production for each group was determined every 9 minutes from the exchange of CO2 and O2. Faeces and urine mixture was quantitatively collected during the balance period to measure energy and nitrogen balance. Total heat production and metabolizable energy costs for maintenance tended (P 0·10) to be higher in the 145 mEq/kg dEB group (681 and 443 kJ/kg0·75 per day respectively) than in the –135 mEq/kg dEB group (660 and 412 kJ/kg0·75 per day respectively). Differences in total heat production between the two dEB groups mainly occurred in the daytime (light period), when significance level was P 0·01. The respiratory quotient and energy retention as fat were numerically (but not statistically significantly) lower in the 145 mEq/kg dEB group compared with –135 mEq/kg dEB. In conclusion, energy balances were similar for both treatments. However in the daytime (light period), piglets needed more energy for maintenance after ingesting a diet with a dEB level of 145 mEq/kg compared to a diet with a dEB level of –135 mEq/kg at a restricted feeding level.

The efficacy of a single injection of oestradiol benzoate, or a combination of pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG), for the induction of a fertile oestrus and ovulation in the prepubertal pig was investigated in two experiments.

In the first experiment, 1·2 mg of oestradiol benzoate induced 21/23 gilts to ovulate, and 22/23 gilts showed oestrus and were inseminated on day 4 or 5 after treatment. At 28 days after insemination, 12 gilts were pregnant and carrying a mean of 7·1 (s.d. 3·3) live embryos, giving an embryonic survival rate of 0·703. All the 22 gilts treated with 400 international units PMSG plus 200 international units HCG as a single injection ovulated but only 10 showed oestrus and were inseminated. At 28 days after insemination, six gilts were pregnant with a mean of 13·0 (s.d. 5·8) live embryos, giving an embryonic survival rate of 0·583.

In the second experiment, 9/11 oestradiol benzoate and 10/10 PMSG/HCG gilts ovulated in response to treatment. Oestrous detection and insemination were delayed until the expected time of the second oestrus, 20 to 30 days after treatment. Nine gilts (3 oestradiol benzoate, 6 PMSG/HCG) showed oestrus in this period and eight were inseminated. Five gilts were pregnant 28 days after insemination with a mean of 11·4 (s.d. 1·1) live embryos, giving an embryonic survival rate of 0·860.

Carcass characters for 365 male castrate cattle of the Africander, Angoni, Barotse and Boran breeds, and the reciprocal crossbreds of the latter three breeds, are reported. In each of the two year-of-birth groups, different slaughter-age/management regimes were used. For all carcass characters, except those related to size, the two sanga breeds, Africander and Barotse, were very similar, as were the two zebu breeds, Angoni and Boran. The introduced breeds, Africander and Boran, which had similar carcass weights, had heavier carcasses (+18 kg, +10%) than the indigenous Barotse and Angoni breeds.

The sanga breed carcasses had less fat cover than those of the zebu breeds. Maternal effects were not important for carcass characters and the Angoni/Barotse and Angoni/Boran crosses showed no heterosis. In the Barotse/Boran crosses, slaughter and carcass weights and eyemuscle area gave between 8% and 9·5% heterosis, and the linear carcass measurements between 2% and 3%.

It was concluded from the management comparisons that there was no economic advantage in delaying slaughter to the later of the two ages compared in the two year-of-birth groups.

Three groups of lambs of about 25 kg live weight were given a concentrate diet either on its own (eight lambs) or supplemented with 10 g/kg ammonium chloride (eight lambs) or 20 g/kg sodium bicarbonate (12 lambs). At about 45 kg live weight the lambs were killed and their body composition was determined. The composition of their gains was also determined using information obtained from a fourth group of lambs (eight lambs) which were killed at the start of the experiment. Lambs given the ammonium chloride diet showed a reduction in blood pH while those given the sodium bicarbonate diet showed an increase to levels seen in lambs given forage diets. There were also marked effects on calcium (Ca), phosphorus (P) and magnesium retention with retentions being reduced in those given the ammonium chloride diet and increased in those given the bicarbonate diet. The average rates of retention of Ca and P in lambs given the bicarbonate diet were 9·1 and 5·9 g/kg empty-body weight gain and are comparable with rates seen in lambs given forage diets. These results suggest that dietary induced changes in blood acid-base status is a major factor contributing to the lower rates of retentions of these minerals in lambs given cereal-based diets.

Forty-eight Hereford × Friesian cows and their South Devon calves were paddock grazed at high or low stocking rates of 412 or 206 cows and calves per ha in experiment 1, and either paddock grazed or set stocked at high or low stocking rates of 4·12 or 2·74 cows and calves per ha in experiments 2 to 4.

There was no significant effect of grazing system on milk yield, milk composition or calf growth but in experiment 2 paddock-grazed cows gained more weight than those set stocked. Cows at low stocking rates gained more weight than those at high stocking rates and, in general, gave more milk. Calf growth rates were also higher at low stocking rates in experiments 1, 3 and 4 but not in experiment 2. Milk composition was not significantly affected by stocking rate. There were substantial increases in calf live-weight gain per ha at the high stocking rate but, because of a lower gain by cows, the differences in total live-weight gains per ha for cows and calves were much smaller.

The nutrient partitioning of growing pigs was altered through nutrition and castration in order to investigate the relationship between serum insulin-like growth factor 1 (IGFl) and protein deposition and serum cholesterol and fat deposition. In a 2 × 2 factorial experiment 18 entire and 18 castrated male pigs, of 20 kg initial live weight, were given either 2·25 (low) or 3·4 (high) times maintenance energy requirements to a scale based on live weight. Nitrogen and energy balances were measured over 7-day periods when the pigs reached about 30, 60 and 90 kg. Fasting blood samples were taken at each weight and serum was analysed for IGFl and insulin and total- and high density lipoprotein (HDL)-cholesterol. Protein and fat deposition, IGFl and cholesterol concentrations were higher for pigs given the high, as opposed to the low, feeding level. Protein deposition and IGFl concentrations were higher for entire males, as opposed to castrated males, whereas fat deposition and cholesterol concentrations were higher in castrated than in entire males. IGFl and protein deposition increased with age for entire but not for castrated males. Conversely, fat deposition increased with age in castrated but not in entire males. There was no effect of age on serum cholesterol. Serum IGFl was correlated with protein deposition at 30, 60 and 90 kg (r = 0·40, r = 0·63 and r = 0·67; P < 0·05, P < 0·002 and P < 0001 respectively, no. = 36). Serum total cholesterol and low density lipoprotein (LDL)-cholesterol were correlated with fat deposition at 60 and 90 kg (r = 0·65 and r = 0·54; both P < 0·001 for total cholesterol; r = 0·66 and r = 0·50; both P < 0·001 for LDL-cholesterol). Insulin levels were similar for pigs in all treatment groups. It is concluded that serum IGFl and cholesterol may give a useful indication of protein and fat deposition in pigs of between 60 and 90 kg live weight.

An experiment was conducted to determine the effect of sucrose as an energy source on energy utilization and protein retention by growing pigs. Growing pigs (20 to 50 kg live weight) were restrictively fed (three times maintenance) either a control wheat-based diet (14 MJ digestible energy (DE) per kg), a sucrose-based diet (15 MJ DE per kg) or a wheat-based diet made i so-energetic with the sucrose diet by the addition of oil. Net energy (NE) content of the diet, energy utilization, protein and fat deposition were measured.

Both the sucrose- and the iso-energetic wheat-based diets improved energy utilization and increased NE retention. They also increased fat deposition (P < 0·05) but had no effect on protein deposition (P > 0·05) compared with the wheat-based control. Increased DE utilization in the sucrose-based diet appeared due to (i) lower dietary fibre, (ii) a better balance of amino acids, or possibly due to (iii) increased fat synthesis due to sucrose metabolism. The lack of effect of sucrose on protein deposition appeared due to either (i) an increased amino acid requirement as a result of the higher NE content of the diet or (ii) preferential use of sucrose for fat deposition.

1. Two growth trials and a digestibility trial were carried out with a total of 84 British Friesian steers to investigate the substitution of root crops for a part of the concentrates in an all-concentrate diet. In Trial 1 six experimental diets were offered ad libitum and contained, on a dry-matter basis, (1) 100% concentrates, (2) 34%, (3) 66%, (4) 87% sliced swedes and (5) 66%, (6) 87% whole potatoes. In Trial 2, five diets were offered ad libitum and contained (1) 100% concentrates or (2) 34%, (3) 50%, (4) 66%, (5) 100% swedes.

2. In both the growth trials when the steers weighed less than 350 kg live weight, daily dry-matter intake was lower for steers offered the highest proportion of swedes than for steers offered concentrates. Substitution of potatoes for concentrates resulted in a higher daily dry-matter intake and daily live-weight gain than did substitution of swedes.

3. In Trials 1 and 2 rate of live-weight gain and in Trial 2 carcass gain were similar for steers on treatments 1 and 2. In Trial 2 liveweight gain declined from 1-05 to 0-87 kg/day and carcass gain declined from 0-62 to 0-51 kg/day between steers on treatments 1 and 5. 4. The replacement of concentrates with swedes or potatoes did not affect the overall digestibility of dry matter.

Thirty one-year-old Charolais × Holstein-Friesian (CH) and Hereford × Holstein-Friesian (HH) steers averaging about 268 kg live weight were used to study the effect of increasing slaughterweight from the traditional 454 kg (1000 lb) to 544 and 635 kg (1200 and 1400 lb) live weight. The steers were fed a growing ration of grain, silage and hay until they weighed 68 kg (150 lb) below the assigned slaughter weight, followed by a finishing ration of grain mixture and maize silage given ad libitum. Average daily gain on the growing ration was 0·91 kg in CH, 14% higher than that in HH steers, while on the finishing ration HH steers, finished at 544 and 635 kg, made higher gains. CH steers were 7·9% more efficient than HH steers in feed conversion. Feed conversion efficiency (total dig. nutrients (kg) per kg live-weight gain) decreased by 10% and 19% respectively as slaughter weight increased to 544 and 635 kg. Live measurements showed that CH steers were generally longer, taller and wider at the hip, whereas HH steers had a greater depth of chest and width of shoulder. CH steers, slaughtered at different weights, had a higher percentage of round and shank, while HH steers had a higher percentage of all other wholesale cuts. Carcass measurements were generally higher in CH than in HH steers. CH steers had a higher percentage of muscle and bone, and lower fat, in the 12th rib. They also had larger areas of m. longissimus thoracis. Fat deposition over and in that muscle was much higher in HH than in CH steers. Under the conditions of this study, 544 kg was found to be the optimum slaughter weight for both groups. Slaughtering steers at 635 kg was found to be economically disadvantageous.

Genetic parameters of veal calves were estimated from data on 510 Danish Red male calves by 39 sires.

Heritability estimates for the growth and carcass traits were low, those for body dimensions and dressing percentage high.

Correlations between the growth and carcass traits indicated no genetic incompatibility in selection.

The problem of achieving simultaneous improvement in the dairy, carcass and growth qualities is discussed. It is suggested that the adoption of performance testing for growth and carcass quality prior to the entry of bulls into AI service, followed by progeny testing for milk and fat yields, would provide the best method of genetic improvement.

Over 2 years, 104 Greyface ewes were mated at a synchronized oestrus either in early October or early November. From late September until slaughter at return to service or between 4 and 7 weeks after mating, ewes were fed to maintain their body condition score as previously adjusted by differential group feeding on grass. Ovulation rate and potential lambing rate were derived from counts of corpora lutea and viable embryos at slaughter. Both rates were higher in the early-mated ewes in comparable body condition. Stress factors were implicated as contributing to the decline in ovulation rate with time, while ewes which failed to hold to first mating were largely responsible for the decline in potential lambing rate.

The relation between the weight of the alimentary tract contents and the weights of body fat and the uterus was examined in 23 Blackface ewes. Six ewes were not pregnant, five had single foetuses and 12 had twins. The pregnant ewes were slaughtered three or four days before their expected lambing date. There was a negative relation between uterine weight or body fat weight and the weight of alimentary tract contents. The effect of uterine weight was small and not significant when only the pregnant animals were considered. It was unlikely that physical restriction of the alimentary tract by the uterus played more than a minor role in limiting voluntary food intake under the conditions of this experiment.

Nutritionists have been discussing whether the dietary supplementation of cyst(e)ine is required as a part of the dietary methionine (Met) in the total sulfur amino acid (TSAA) requirement to achieve optimum performance in broilers. Part of Met is converted to cysteine (Cys) to meet the Cys requirement, especially for feather growth. The TSAA requirement has been determined by using graded levels of free Met in the diet, without supplementation of free cyst(e)ine. It has also been argued that the Met to Cys ratio (Met : Cys) changes with age and even with different Met sources. The objective of this study was to evaluate the two sources of Met, while determining the proportion of Met and Cys in total dietary TSAA that optimize the performance of broilers. A performance assay was carried out in a factorial arrangement (5 × 2) using 1080 broilers from 42 to 56 days of age fed diets having different dietary proportions of Met and Cys (44 : 56, 46 : 54, 48 : 52, 50 : 50 or 52 : 48) while maintaining the same dietary TSAA in the diets. Two synthetic Met sources (dl-Met or l-Met) were used for each of the diets with different dietary Met : Cys ratios. Twenty-one broilers of the same age were fed the diets 44 : 56, 48 : 52 and 52 : 48 by supplementing the diet with L-(15N) Met or L-(15N2) Cystine to study the metabolism of TSAA. No differences were observed between Met sources for feed intake, BW gain and feed conversion ratio (FCR; P > 0.05); however, FCR was numerically improved at 50 : 50 Met : Cys. Regarding TSAA utilization, the conversion of Met to Cys increased with increase in Met : Cys ratios, but the concentration of Met intermediates decreased. Broiler chickens responded to different dietary proportions of sulfur amino acids by altering their sulfur amino acid metabolism, and diets containing 50 : 50 Met : Cys is recommended for broilers of age 42 to 56 days.

Furnished cage housing for laying hens has been introduced in some countries as a ‘welfare-friendly’ alternative to conventional cage systems. Whether this housing system would be acceptable to the public remains unknown. This pilot study aimed to engage the public through online discussions in order to investigate their knowledge, support and perception of laying hen welfare housed in furnished cages. During these discussions, a science-based information statement about furnished cages was introduced. Through a mixed method approach, surveys to assess beliefs and knowledge were administered to participants before and after the online discussion. We qualitatively analysed the online discussion transcripts to determine recurrent themes, and quantitatively measured levels of knowledge and support for furnished cages using pre- and post-forum surveys. Support for the introduction increased from 55% pre-forum to 65% post-forum. Additionally, the participants’ perceived welfare of laying hens in furnished cages and objective knowledge of furnished cages significantly increased after online discussion. These results suggest that engagement with the public combined with the delivery of science-based information may be important factors when considering whether to introduce new farming practices. Trust in industry through transparency and willingness to engage in discussions with the public might also mitigate public concerns.

Glucocorticoids (GCs) are counterregulatory hormones with broad effects on the digestion and absorption of dietary carbohydrates, lipids and proteins, but the underlying molecular mechanisms of these effects remain unclear. The present experiment was conducted to investigate the main expression sites of nutrient transporters and the effects of GCs on the gene expression of these transporters in the rabbit small intestine. The results showed that peptide transporter 1 (PepT1), facultative amino acid transporter (rBAT), neutral amino acid transporter (B0AT), excitatory amino acid transporter 3 (EAAT3), sodium-glucose transporter 1 (SGLT1) and glucose transporter 5 (GLUT5) were mainly expressed in the distal segment, glucose transporter 2 (GLUT2) and fatty-acid-binding protein 4 (FATP4) were mainly expressed in the proximal segment and cationic amino acid transporter 1 (CAT1) was mainly expressed in the middle segment of the rabbit small intestine. In addition, we analysed the effects of 3 h (short-term) or 7 days (long-term) dexamethasone (DEX) treatment on the gene expression of most nutrient transporters. The results showed that short-term DEX treatment significantly decreased PepT1, B0AT, EAAT3, rBAT and SGLT1 expressions in all small intestinal segments, while it significantly decreased GLUT2 in the duodenum and FATP4 in the duodenum and ileum (P < 0.05). Long-term DEX treatment also significantly decreased PepT1, CAT1, B0AT, EAAT3, rBAT and SGLT1 in all small intestinal segments and significantly decreased GLUT2 in the jejunum and FATP4 in the ileum (P < 0.05). In conclusion, DEX could decrease the gene expression of most nutrient transporters (except GLUT5) and affect the transport of intestinal amino acids, monosaccharides and fatty acids.

Black and White dual-purpose cattle (DSN) are kept in diverse production systems, but the same set of genetic parameters is used for official national genetic evaluations, neglecting the herd or production system characteristics. The aim of the present study was to infer genetic (co)variance components within and across defined herd descriptor groups or clusters, considering only herds keeping the local and endangered DSN breed. The study considered 3659 DSN and 2324 Holstein Friesian (HF) cows from parities one to three. The 46 herds always kept DSN cows, but in most cases, herds were ‘mixed’ herds (Mixed), including both genetic lines HF and DSN. In order to study environmental sensitivity, we had a focus on the naturally occurring negative energy balance in the early lactation period. In consequence, traits were records from the 1st official test-day after calving for milk yield (Milk-kg), somatic cell score (SCS) and fat-to-protein ratio (FPR). Genetic parameters were estimated in bivariate runs (separate runs for the three genetic lines Mixed, HF and DSN), defining the same trait from different herd groups or clusters as different traits. Additive-genetic variances and heritabilities were larger in herd groups that indicated superior herd management, implying that cow records from these herds allow a better genetic differentiation. Superior herd management included larger herds, low calving age, high herd production levels and low intra-herd somatic cell count. Herd descriptor group differences in additive-genetic variances for Milk-kg were stronger in HF than in DSN, indicating environmental sensitivity for DSN. Similar variance components and heritabilities across groups, clusters and genetic lines were found for data stratification according to geographical descriptors altitude and latitude. Considering 72 bivariate herd group runs, 29 genetic correlations were very close to 1 (mostly for Milk-kg). Somatic cell score was the trait showing the smallest genetic correlations, especially in the DSN analyses, and when stratifying herds according to genetic line compositions (rg=0.11), or according to the percentage of natural service sires (rg=0.08). For estimations based on the results of a cluster analysis considering several herd descriptors simultaneously, indications for genotype × environment interactions could be found for SCS, but genetic correlations were larger than 0.80 for Milk-kg and FPR. In conclusion, we suggest multiple-trait animal model applications in genetic evaluations, in order to select the best sires for specific herd environments or herd clusters.

According to EU legislation, group-housed gestating sows must have a minimum of 2.25 m2 floor area per sow with at least 1.3 m2 of continuous solid floor of which a maximum of 15% is reserved for drainage openings. The aim of the experiment was to quantify the impact of different drainage openings on ammonia and greenhouse gas emissions. Three successive batches of 10 gestating sows were used. Each batch was divided into two groups kept separately in two identical rooms with similar volume and surface. The solid part of the floor presented 15% drainage openings in the first room and 2.5% in the second room. The gas emissions (ammonia (NH3), methane (CH4), nitrous oxide (N2O), carbon dioxide (CO2) and water vapour (H2O)) were measured three times during 6 consecutive days. Gaseous emissions were significantly lower with 15% drainage openings with reductions of 19% for NH3 (12.77 v. 15.83 g/day per sow), 15% for CH4 (10.15 v. 11.91 g/day per sow), 10% for N2O (0.47 v. 0.52 g/day per sow), 9% for CO2 (2.41 v. 2.66 kg/day per sow) and 13% for H2O (3.25 v. 3.75 kg/day per sow). This trial showed the advantage, in an environmental point of view, to use 15% drainage openings on the solid part of partly slatted floors in pens for group-housed gestating sows.