The fruit of Ligustrum lucidum (FLL, Nuzhenzi in Chinese) is an important traditional medicine, and have attracted significant research attention because of their various biological activities. However, there are few research reports available on the use of FLL as a feed additive in livestock nutrition, particularly in layers. This study was conducted to determine the effects of supplementation of the diet of laying hens with FLL on laying performance, egg quality and blood metabolites. A total of 360 72-week-old hens were allocated to three dietary treatments (eight replications of 15 hens/treatment group) and were fed either a control diet or a diet supplemented with an inclusion level of 0.25% or 0.50% of FLL powder in the final feed, until 78 weeks of age. Hens were housed in a three-tier cage system. Feed and water were provided ad libitum. Blood samples and eggs were collected at the end of the experiment. The results showed that dietary supplementation with FLL did not affect egg weight, feed conversion ratio, eggshell thickness, albumen height, egg yolk color, eggshell breaking strength or egg shape index. However, FLL supplementation significantly decreased (P<0.001) mortality, cracked-egg rate and blood serum levels of cholesterol, low-density lipoprotein cholesterol, triglycerides and alanine aminotransferase, and increased (P<0.001) blood serum levels of high-density lipoprotein cholesterol. No differences in serum levels of total protein, albumin, glucose, calcium, aspartate aminotransferase or alkaline phosphatase were observed in hens fed FLL compared with the control group. It can be concluded that FLL, at a supplementation level of 0.25% final feed, can be used as an effective feed additive to improve the performance of laying hens during the late laying period.

In pig husbandry, pregnant females are often exposed to stressful conditions, and their outcomes on maternal and offspring health have not been well evaluated. The present study aimed at testing whether improving the welfare of gestating sows could be associated with a better maternal health during gestation, changes in the composition of lacteal secretions and improvement in piglet survival. Two contrasted group-housing systems for gestating sows were used, that is, a French conventional system on slatted floor (C, 49 sows) and an enriched system using larger pens on deep straw (E, 57 sows). On the 105th days of gestation (DG105), sows were transferred into identical farrowing crates on slatted floor. Saliva was collected from all sows on DG35, DG105 and DG107. Blood samples were collected on DG105 from all sows and on the 1st day of lactation (DL1) from a subset of them (C, n=18; E, n=19). Colostrum and milk samples were collected from this subset of sows at farrowing (DL0) and DL4. Saliva concentration of cortisol was greater in C than in E sows at DG35 and DG105, and dropped to concentrations comparable to E sows after transfer into farrowing crates (DG107). On DG105, plasma concentrations of haptoglobin, immunoglobulins G (IgG) and A (IgA), blood lymphocyte counts and plasma antioxidant potential did not differ between groups (P > 0.10), whereas blood granulocyte count, and plasma hydroperoxide concentration were lower in E than in C sows (P < 0.05). Concentrations of IgG and IgA in colostrum and milk did not differ between the two groups. The number of cells did not differ in colostrum but was greater in milk from E than C sows (P < 0.05). Pre-weaning mortality rates were lower in E than C piglets (16.7% v. 25.8%, P < 0.001), and especially between 12 and 72 h postpartum (P < 0.001). Plasma concentration of IgG was similar in E and C piglets on DL4. In conclusion, differences in salivary cortisol, blood granulocyte count and oxidative stress markers between groups suggested improved welfare and reduced immune solicitation during late gestation in sows of the E compared with the C system. However, the better survival observed for neonates in the E environment could not be explained by variations in colostrum composition.

Low phosphorus (P) digestibility combined with intensive pig production can increase P diffuse pollution and environmental load. The aim of this paper was to develop a deterministic, dynamic model able to represent P digestion, retention and ultimately excretion in growing and finishing pigs of different genotypes, offered access to diets of different composition. The model represented the limited ability of pig endogenous phytase activity to dephosphorylate phytate as a linear function of dietary calcium (Ca). Phytate dephosphorylation in the stomach by exogenous microbial phytase enzymes was expressed by a first order kinetics relationship. The absorption of non-phytate P from the lumen of the small intestine into the blood stream was set at 0.8 and the dephosphorylated phytate from the large intestine was assumed to be indigestible. The net efficiency of using digested P was set at 0.94 and assumed to be independent of BW, and constant across genotype and sex. P requirements for both maintenance and growth were made simple functions of body protein mass, and hence functions of animal genotype. Undigested P was assumed to be excreted in the feaces in both soluble and insoluble forms. If digestible P exceeded the requirements for P then the excess digestible P was excreted through the urinary flow; thus the model represented both forms of P excretion (soluble and insoluble) into the environment. Using a UK industry standard diet, model behaviour was investigated for its predictions of P digestibility, retention and excretion under different levels of inclusion of microbial phytase and dietary Ca, and different non-phytate P : phytate ratios in the diet, thus covering a broad space of potential diet compositions. Model predictions were consistent with our understanding of P digestion, metabolism and excretion. Uncertainties associated with the underlying assumptions of the model were identified. Their consequences on model predictions, as well as the model evaluation are assessed in a companion paper.

Pig studies on non-starch polysaccharides (NSPs) have mainly focused on finishing and breeding animals because their digestive capacity and ability to ferment fibre are considered greater than piglets. In this study, growth and nutrient digestibility, with particular reference to NSP constituent monomers, were evaluated in piglets offered contrasting sources of NSPs. The potential for enhancing growth performance and digestibility with exogenous food enzymes (xylanase, amylase, pectinase and beta-glucanase) was investigated. A total of 240 piglets weaned at 28 days of age, in groups of six, were allocated to six treatments in a 3×2 factorial design, diet type (W, B and SBP) by enzyme supplementation (–v. +). Diet W was wheat based and formulated to supply 14 MJ digestible energy (DE) per kg. In diets B and SBP, DE was reduced to 13·25 MJ/kg by replacing wheat with barley (708 g/kg) or with 185 g/kg dried unmolassed sugar beet pulp. Growth was monitored over 4 weeks. Digestibility of diets B–, B+, SBP– and SBP+ was evaluated in 16 piglets, in groups of four, using a 4×4 Latin-square design. In the growth study, mean initial and final piglet weights were 8·1 (s.e. 0·09) and 18·0 (s.e. 0·21) kg. Piglet health remained satisfactory and food intake averaged 523 (s.e. 6·7) g/day. There were no consistent and significant effects of diet type on food intake, live-weight gain or food conversion, except in week 1 when gain on diet W was higher than on diets B and SBP, 191 v. 150 v. 125 g/day, respectively (s.e.d. 20·0, P < 0·05). Enzyme supplements enhanced the conversion of food to gain over 4 weeks (1·56 v. 1·50:1, s.e.d. 0·030, P < 0·05). Piglets given diet SBP produced faeces with a lower dry-matter content (181 v. 246 g/kg, s.e.d. 10·8, P < 0·001) but with no visual evidence of a nutritionally induced diarrhoea. There were no significant differences in apparent faecal digestibility coefficients (AFDC) for dry matter, crude protein and gross energy between diets B and SBP. AFDC for soluble, insoluble and total NSP constituent monomers were higher (P < 0·001) in diet SBP. Soluble uronic acids were the most readily digested NSP constituents in diet SBP, showing a mean AFDC of 0·96 (s.e. 0·005). Apparent faecal digestibility was not an appropriate indicator for supplementary enzyme activity in the intact digestive tract of piglets given diets rich in fermentable NSPs. Piglets given the diets supplemented with enzymes excreted increased concentrations of urinary pentoses, especially arabinose (0·113 v. 0·136 mg/ml, s.e.d. 0·0107, P < 0·05). Urinary arabinose and xylose concentrations were also increased (V < 0·001) with feeding SBP, indicating that some of the microbially released NSP sugars escaped fermentation and were directly absorbed. In conclusion, piglets were able to use simple diets, containing high and contrasting sources of NSPs to support satisfactory rates of live-weight gain. Supplementation with NSP degrading enzymes enhanced the conversion of food to live-weight gain. Urinary NSP derived sugars provided indirect evidence of NSP hydrolysis by supplementary enzymes and gut microbes.

Nineteen round white-feed peas (FP) varieties, six coloured-flowered peas (CP) varieties and four wrinkled white-flowered peas (WP) varieties were given to growing pigs in order to measure their feeding value. Mean values of energy apparent digestibility measured at the faecal level of FP, CP and WP were respectively 0·886, 0·812 and 0·823. Mean values for digestible energy were 16·34, 1506 and 15·60 M]l kg dry matter. Mean values of faecal apparent digestibility of protein were 0·840, 0·760 and 0·828. The lower energy and crude protein (CP) apparent digestibility of CP relative to FP can be explained by their higher fibre content and by the presence of condensed tannins whilst the lower energy and CP apparent digestibility in WP relative to FP can be explained by their higher fibre content, their lower starch content and their higher amylosel amylopectine ratio. Among the feed peas, there was no difference between peas with low trypsin inhibitor activity and peas with medium trypsin inhibitor activity.

In an experiment carried out on five farms in 3 years and comprising 1221 annual weight records of adult ewes, an increased level of feedingwas comparedwith feeding according to farming practice. The higher feeding level started 6 weeks before mating andfinishedjust before lambing. Significant effects of feeding level on ewe live weight and body condition, ewe fecundity and the birth and weaning weights of lambs were found.

Ewe fecundity increasedlinearly with ewelive weight at 8 weeks prior t o mating (b=1·05 lambs/kg per 100 ewes), curvilinearly with ewe body condition score at 8 weeks before mating (maximum at score 3·32) and curvilinearly with weight gain from 8 to 2 weeks before mating (maximum at 2·3 kg gain). A 10% range in live weight, condition score and live-weight gain resulted in a predicted fecundity range of 21 lambs per 100 ewes alive at lambing. Changes in weight and condition score during the mating period did not affect ewe fecundity.

Avian embryogenesis can be manipulated by alteration of the temperature during incubation of the brooding egg. Investigations in turkeys showed that a higher temperature during early embryogenesis positively affects the myogenesis accompanied with a higher muscle fibre number (MFN). The aim of this study was to transfer this result to broiler and to investigate if an alteration of the temperature also affects the meat quality after slaughter of the birds. Therefore brooding eggs of the Cobb 500 broiler genetic were either incubated at 37.5°C during the whole incubation period (at normal temperature (NT)), or at 38.5°C during embryonic day (ED) 7 to 10 (at high temperature (HT)). After hatch the chicks were sexed and reared up to an age of 36 days in an experimental stable. Growth and feed conversion properties were determined during this period. After slaughter different meat quality characteristics as well as the muscle microstructure were analysed. The hatch rate and chick weight did not differ between the broiler of the NT and HT group. After 36 days the final body weights and the cumulative feed conversion rates were not different in the NT and HT groups. No differing results were obtained with regard to the slaughter, breast and leg weights of the NT and HT animals. Considering the gender of the animals no differences in the slaughter characteristics could be determined although the carcass and breast weights of the HT cocks were tendentially higher. The muscle fibre areas and MFNs in the breast muscles of the NT and HT cocks did not differ significantly and were in the range of the HT hens. Only the NT hens had significantly larger muscle fibres and less MFN than the other animals. With regard to the meat quality characteristics no clear differences of the pH, electrical conductivity (EC) and colour (L*a*b*) values were found. The L*a*b* values in the investigated breast muscles of all broilers usually increased during ageing. The increase of the incubation temperature had no impact on the hatch, growth, slaughter and meat quality characteristics of the broiler except for the tendentially higher carcass and breast weights of the HT cocks. However, the decrease of the fibre areas in the HT hens is an interesting effect of using a higher incubation temperature, which needs to be considered when implicating further investigations.

The main objective of this study was to investigate the relationship between partitioning and isotopic fractionation of nitrogen (N) in sheep consuming diets with varying ratios of N to water-soluble carbohydrate (WSC). Six non-lactating sheep were offered a constant dry matter (DM) allowance with one of three ratios of dietary N/WSC, achieved by adding sucrose and urea to lucerne pellets. A replicated 3 dietary treatments (Low, Medium and High N/WSC) × 3 (collection periods) and a Latin square design was used, with two sheep assigned to each treatment in each period. Feed, faeces, urine, plasma, wool, muscle and liver samples were collected and analysed for 15N concentration. Nitrogen intake and outputs in faeces and urine were measured for each sheep using 6-day total collections. Blood urea N (BUN) and urinary excretion of purine derivative were also measured. Treatment effects were tested using general ANOVA; the relationships between measured variables were analysed by linear regression. BUN and N intake increased by 46% and 35%, respectively, when N/WSC increased 2.5-fold. However, no indication of change in microbial protein synthesis was detected. Results indicated effects of dietary treatments on urinary N/faecal N, faecal N/N intake and retained N/N intake. In addition, the linear relationships between plasma δ15N and urinary N/N intake and muscle δ15N and retained N/N intake based on individual measurements showed the potential of using N isotopic fractionation as an easy-to-use indicator of N partitioning when N supply exceeds that required to match energy supply in the diet.

The forage: concentrate ratio in the diet is known to influence the fermentation characteristics in the rumen (Sudweeks, Ely, Mertens and Sisk, 1981). Increasing the proportion of concentrates in rations fed to dairy cows has been shown to narrow the acetate plus butyrate: propionate ratio in the rumen (Sutton, 1981) with an associated depression in milk fat concentration (Ørskov, Reid and McDonald, 1981). The magnitude of the effect, on milk yield and composition, of increasing the concentrate proportion in the ration has been shown to be dependent on feeding level (Sutton, 1981), and the number of meals of concentrate per day (Johnson, 1979) and also may be influenced by dietary protein level and source (Ørskov et al., 1981).

Two respiratory chamber experiments were conducted with dairy cows to compare metabolizable energy and protein utilization when feeding white or red clover with ryegrass. In experiment 1, fresh ryegrass was mixed with fresh white (WF) or red clover (RF) (60/40, on dry matter (DM) basis). Experiment 2 involved similar mixed diets in ensiled form (WS and RS, respectively), and two ryegrass silage diets, without (GS) or with supplementary maize gluten (GS+). Barley was supplemented according to requirements for milk production. Voluntary forage DM intake remained unaffected in experiment 1 and was higher (P<0·01) in experiment 2 for WS than for GS and GS+(128 v. 98 and 106 g/kg M0·75). Within experiments, no treatment effects occurred for apparent nutrient digestibilities, milk yield, and composition. Protein utilization (milk-N/N-intake) was numerically lower on all clover-based diets (0·24 to 0·25) versus GS (0·29). With added maize gluten (GS+), protein utilization decreased to 0·23, indicating that ryegrass silage (plus barley) alone provided sufficient metabolizable protein. Consequently, higher (P<0·01) urinary energy losses occurred in GS+ compared with GS, despite similar metabolizable energy intakes, and a trend for the highest plasma urea levels was found for GS+ cows (7·59 mmol/l; P<0·1). Overall, this study illustrates that the white and red clovers investigated were equivalent in energy and protein supply, also in comparison to the ryegrass. It remains open whether these forage legumes, when supplemented to a moderate-protein ryegrass, would have contributed to metabolizable protein supply or would have merely increased metabolic nitrogen load.

In the past few years, genetically modified (GM) crops aimed at producing food/feed that became part of the regular agriculture in many areas of the world. However, we are uncertain whether GM food and feed can exert potential adverse effects on humans or animals. Of importance, the reproductive toxicology of GM crops has been studied using a number of methods, and by feeding GM crops to a number species of animals to ensure the safety assessment of GM food and feed. It appears that there are no adverse effects of GM crops on many species of animals in acute and short-term feeding studies, but serious debates of effects of long-term and multigenerational feeding studies remain. The aims of this review are to focus on the latest (last 3 to 4 years) findings and debates on reproduction of male and female animals after feeding daily diets containing the GM crops, and to present the possible mechanism(s) to explain their influences.

Toxoplasmosis is one of the five parasitic diseases considered as a priority for public health action. The consumption of raw milk products represents a possible risk, in particular for certain categories of people. The aim of this study was to evaluate the possible effects of Toxoplasma gondii on milk yield and quality in sero-positive animals with parasitemia. Eighteen healthy lactating Amiata jennies, between 90 and 180 days were included in the study. Four donkeys scored positive for immunofluorescent antibody test (IFAT), and each IFAT positive donkey presented parasitic DNA both in the blood and milk. No significant differences were found between milk yield in PCR-positive donkeys compared with the negative cases, however the former tended to have a greater production. Milk quality in the positive donkeys showed a significantly lower percentage of casein (0.72% v. 0.81%) and ash (0.32% v. 0.37%). Positive cases had a highly significant larger average diameter of globules (2.35 µm) and fewer globules/ml (2.39×108). Somatic cell and bacterial counts were normal and in agreement with the literature. Toxoplasma gondii did not seem to present clinical forms in lactating jennies. Further in vivo studies are needed to further assess the risk of T. gondii transmission through donkey milk, together with the impact of different stages of infection on milk quality.

The purpose of this study was to investigate potential mechanisms involved in fat deposition promoted by dietary lysine deficiency, particularly intramuscular fat (IMF), and differential responses between fatty and lean pigs. Carcass traits and lipogenic enzyme activities and gene expression levels in muscles and adipose tissue were investigated in Iberian (fatty) and Landrace × Large White (LDW) pigs under identical feeding level (based on body weight (BW)) and management conditions. Twenty-eight barrows of 10 kg initial BW, 14 per breed, were fed two isoproteic (200 g CP /kg DM) and isocaloric (14.7 MJ metabolizable energy/kg DM) diets with identical composition except for the lysine content (1.09% for diet adequate in lysine and 0.52% for diet deficient in lysine). At a BW of 25 kg, pigs were slaughtered. Compared with pigs fed the lysine-adequate diet, in both genotypes lysine-deficient diet led to lower carcass protein concentration, lower relative proportions of leaner components (loin, ham and shoulder; P < 0.01), and higher carcass fatty components and carcass lipid concentration (P < 0.001). Irrespective of diet, the activity and gene expression of lipogenic enzymes (fatty acid synthase (FAS), malic enzyme (ME) and glucose-6-phosphate dehydrogenase (G6PDH)) were greater in Iberian than in LDW pigs, particularly in adipose tissue where transcriptional regulators involved in the control of adipogenesis and lipogenesis were also upregulated in Iberian animals. In backfat tissue, there was a small decrease induced by or no effects of lysine-deficient diet on the activity and gene expression of lipogenic enzymes, nor in gene expression levels of upstream regulators of lipogenesis and adipogenesis. In longissimus muscle, the activity of FAS, G6PDH and ME increased with lysine deficiency in both genotypes (P < 0.01) and an upregulation of gene expression of lipogenic enzymes was specifically observed in Iberian pigs (P < 0.05 to P < 0.001). In biceps femoris muscle of lysine-deficient pigs, the activity of FAS and ME enzymes increased, ME1 gene was upregulated (added to FASN gene in the case of Iberian pigs; P < 0.01 to P < 0.001) and PPARA gene was downregulated (P < 0.05). The results show that in both fatty and lean pigs, the effect of lysine deficiency on lipid metabolism was tissue-specific, with an activation of lipogenesis in longissimus and biceps femoris muscle but no apparent stimulation in backfat adipose tissue. Suitable feeding protocols including lysine-deficient diets should be designed for each pig type in order to increase intramuscular lipids without penalizing the growth of lean carcass components.

1. A growth trial was carried out with 21 Friesian steers given diets containing either 0%, 30% or 50% ground straw, and concentrates up to 100%.

2. Steers offered the diet containing 0% straw consumed less dry matter per day than steers on the other two treatments.

3. Rates of live-weight gain were 1·20, 1·04 and 0·87 kg/day for the three treatments respectively, and carcass gains were 690, 550 and 440 g/day.

4. Killing-out percentage dropped and alimentary-tract fill increased as the proportion of straw in the diet increased.

5. The dry-matter digestibility coefficients for the three diets, determined at maximal intake, were 79·1%, 62·3% and 56·6%, respectively.

An experiment was carried out to study the effect of changes in either the quality or the quantity of dietary protein intake on the free essential amino acid profiles in plasma, muscle or liver of growing chickens. Following a randomized paired-feeding design based on metabolic body weight (kg M0·75), White Rock male broilers were allocated to one of three isoenergetic (14·5 kJ metabolizable energy per g dry matter (DM)) semisynthetic diets containing different levels of protein (60, 120, 180 or 240 g/kg DM). All diets were based on soya-bean meal, as the sole source of protein, either unsupplemented (diets S) or supplemented with 20 g/kg L-lysine (diets SL) or 2 g/kg DL-methionine (diets SM). Samples of blood, biceps muscle and liver were taken and amino acid analysis was determined by high performance liquid chromatography. Plasma was only adequate to detect the effect of the supplementation with methionine to balance the dietary amino acid (AA) profile. Plasma concentrations of free methionine significantly increased as a result of the supplementation with methionine (P < 0·001) and remained unaffected by the amount of protein ingested. When lysine was added to diets S to induce an AA imbalance, a significant increase in muscle concentrations of free valine, isoleucine and phenylalanine (P <0·05) and a significant decrease in liver concentrations of free arginine and phenylalanine were observed (P<0·05). The supplementation with DL-methionine gave rise to a significant fall in the concentrations of free histidine, glycine and threonine (P < 0·05) and increased those of isoleucine and methionine in the skeletal muscle (P < 0·05), while in liver it significantly lowered the concentrations of free arginine, valine, leucine, phenylalanine and methionine (P < 0·001 to P < 0·05) and raised that of free glycine (P < 0·001). The ratios lysine: phenylalanine, lysine: valine and methionine: glycine in muscle together with that of methionine: glycine in liver seem to be appropriate indexes of the adequacy of the dietary AA profile to requirements.

The effects of diets formulated to have two rates of organic matter (OM) release and to be either synchronous or asynchronous with respect to their hourly release of nitrogen (N) and OM in the rumen on the growth, intake and metabolism of ewe lambs was studied. In experiment 1, the in situ degradation characteristics of N and OM for 16 food ingredients was determined. The foods varied considerably in their chemical composition and degradability coefficients of N and OM. Based on this information, four diets were formulated to differ in their rate of N and OM release in the rumen but to have a similar content of metabolizable energy (10·4 MJ/kg dry matter (DM)), crude protein (140 g/kg DM), daily ratio of N: OM released (34 g N per kg OM) and digestible undegradable protein (32 g/kg DM) but to be synchronous or asynchronous with respect to hourly N: OM ratio. The four diets were slow energy, synchronous (SS), slow energy asynchronous (SA), fast energy, synchronous (FS) and fast energy asynchronous (FA).

In experiment 2 the four diets were offered ad libitum to 24 ewe lambs of an initial live weight of 25 kg in a 2 × 2 factorial design. Lambs were slaughtered at 40 kg live weight. Animals offered diets FS and FA had a higher growth rate than those offered diets SA and SS (266 v. 225 g/day respectively; P < 0·05). There was a significant interaction between rate ofOM and N release on DM intake (DMI) with lambs offered diet FS consuming less than those offered FA (1·47 v. 1·67 kg DM per day; P < 0·05). Rate of energy release and synchrony had an effect on food conversion efficiency (FCE; kg gain per kg DMI) with lambs offered diets FS and FA having a greater FCE than those offered SS and SA (0·170 v. 0·146 respectively; P < 0·001) and those offered diets SS and FS had a greater FCE than those offered diets SA and FA (0·164 v. 0·152 respectively; P < 0·05). Diet had little effect on carcass composition. The proportion of propionate in rumen fluid was greater in lambs offered diets FS and FA than in those offered diets SS and SA (222 v. 168 mmol/mol respectively; P < 0·01). Plasma urea concentrations exhibited a cyclical trend throughout the day with highest concentrations occurring 2 h after fresh food was offered. Lambs offered diet FS had lower plasma urea concentrations at 6, 10 and 14 h after feeding. Plasma concentrations of ß-hydroxybutyrate were lower throughout the day in lambs offered diet FS. The current findings are consistent with the view that a rapid release of OM and synchronizing hourly N: OM release in the rumen can improve the efficiency of growth through improvements in protein and/or energy metabolism.

Three ewes, three female goats and three male fallow deer, aged between 7 and 12 months and weighing 24·0 to 32·2 kg, were used in this experiment to outline the main differences in digestion among the three species. Dietary treatments were three diets with three forage: concentrate ratios of 10: 90, 50: 50, and 90:10 and two different feeding levels (45 and 90 g/kg M0·75 per day). The three diets were given to the three animals of each species in a Latin-square design; the two levels of feeding were compared ivithin diet in each period of the Latin square. The diet selected, apparent digestibility, and rumen retention time of Cr-mordanted neutral-detergent fibre were significantly different among species and dietary treatments. Interactions between species and dietary treatments were also significant for all the above variables. Sheep showed the highest intakes and apparent digestibilities of the forage-rich diets, and the longest rumen mean retention times. Goats tended to select diet components, despite allowance of diets being limited, and had lower food intakes than sheep. Apparent digestibility of forage-rich diet was also lower. Rumen mean retention times were shorter and less influenced by dietary treatments. Fallow deer had an apparent digestibility of forage-rich diets which was even lower than that of goats. Food intake was similar to that of sheep, with no evidence of selection. Rumen mean retention time was shorter than that of goats.

Six lactating Friesian cows (three high and three low breeding index cows) were subjected to a total of 28 complete energy and nitrogen balances during early and late lactation. In addition, 12 non-lactating Friesian cows (six high and six low breeding index cows) were offered individually pasture indoors for 62 days, beginning at approx. 180 days of pregnancy. Cows within each genotype were randomly allocated to feeding levels which were nominally equivalent to their requirements for maintenance or twice maintenance. Eight of the 12 cows (four high and four low breeding index) were each subjected to two energy balance periods at approx. 210 (period 1) and 230 (period 2) days of pregnancy.

When offered pasture ad libitum during lactation, cows with high breeding indexes consumed significantly more gross energy per unit of metabolic live weight (P < 0·05) than did cows with low breeding indexes, but the two genotypes did not differ in their ability to metabolize the gross energy of the food, or in the individual losses of energy in faeces, urine or methane.

There were no significant differences between genotypes in their heat production at a common energy intake except during restricted feeding in early lactation when high breeding index cows produced less heat than did low breeding index cows (P < 0·05). During lactation high breeding index cows retained a higher proportion of their total energy retention (milk + body tissue energy) as milk in late lactation (P < 0·01) but not in early lactation.

For non-lactating cows, both genotypes required similar amounts of metabolizable energy to maintain zero maternal body energy retention, 0·79 and 0·80 MJ/M0·75 for periods 1 and 2 respectively. The efficiency with which metabolizable energy was converted to net energy (kg) was similar for both genotypes at both stages of pregnancy, the mean value being 0·52. The metabolizable energy required to maintain body condition was estimated to be 0·78 and 0·71 MJ/M0·75 for high and low breeding index cows respectively. The metabolizable energy required in excess of maintenance to promote a gain of one unit of body condition was estimated to be 2290 MJ. This is equivalent to 27 MJ energy retained per kg live-weight gain.

For lactating and non-lactating cows the differences between genotypes in their utilization of nitrogen were small and inconsistent.

A total of 64 intensively reared Friesian steers were used in a 2×2×2 design to study the effects of age of castration (15 days old v. 5 months old), dietary protein level (14.6% v. 16.8%; DM basis) and lysine/methionine (lys/met) ratio (3.0 v. 3.4) on meat quality. The lys/met ratio of 3.0 was reached with supplementation of protected methionine. Animals were slaughtered at a live weight of 443.5±26.2 kg at around 12 months of age. Colour and lipid oxidation were measured in the longissimus thoracis muscle throughout the 14 days of display under modified atmospheric and commercial display conditions. A panel of 17 consumers assessed daily the visual acceptability of the meat on display. A consumer acceptability eating test was also performed with 120 consumers in meat aged for 7 days under vacuum conditions. Lipid oxidation was not influenced by castration age and the protein level in the diet. Castration age did not affect meat colour, but meat from the low protein level diet and the low lys/met ratio showed higher redness (a*) from 3 days of display onwards. Nevertheless, from 6 days onwards, consumer visual acceptability was below the level of acceptance in all treatments, and even from 5 days onwards in those animals that underwent early castration and were fed either a high protein diet or a combination diet low in protein content and high in lys/met ratio. The best accepted treatments throughout the display period were those from late castrated animals fed a low protein diet, probably related to other visual aspects. However, the best accepted meat after consumption was that from late castrated animals fed high protein and high lys/met. The addition of protected methionine to reach lys/met levels of 3.0 did not improve beef acceptability, with the high protein diet being preferred by consumers in terms of palatability in late castrated animals.

Improving the amino acid (AA) profile of the diet by using l-Lys, l-Thr, dl-Met, l-Trp and l-Val helps to reduce the dietary CP content, thereby reducing nitrogen excretion while maintaining the performance of pigs. Valine is the fifth limiting AA in cereal–soybean meal-based diets. The extent to which the CP content in the diet can be reduced further without compromising performance depends on the requirement of the next limiting AA. In cereal–soybean meal-based diets, Ile, His and Leu may be the limiting AAs after Val, although information on the requirements for these AAs is scarce. Six experiments were conducted to determine the effect of supplementing a low-CP diet with l-Ile, l-His and l-Leu on the performance of pigs weighing 10 to 20 kg. Experiment 1 was designed to determine the most limiting AA with respect to performance among Ile, His and Leu. A diet 10% deficient in Ile, Leu and His relative to the National Research Council (NRC, 1998) requirement estimates tended to decrease daily feed intake and daily gain by 6% and 8%, respectively. A 10% deficiency in His alone had no effect, whereas a 10% deficiency in Ile or Leu slightly reduced daily feed intake and gain. In the remaining experiments, the standardized ileal digestible (SID) Ile : Lys, His : Lys and Leu : Lys requirements were estimated. In Experiments 2, 3, 4, 5 and 6, 14 blocks of six pigs each were assigned to six levels of SID Ile : Lys (40%, 43%, 46%, 49%, 52% and 55%), His : Lys (20%, 24%, 28%, 32%, 36% and 40%), His : Lys (21%, 24%, 27%, 30%, 33% and 36%), Leu : Lys (70%, 78%, 86%, 94%, 102% and 110%) and Leu : Lys (80%, 90%, 100%, 110%, 120% and 130%), respectively. Across experiments, the estimated SID Ile : Lys, His : Lys and Leu : Lys requirements for maximizing daily gain were 49%, 32% and 102%, respectively, using a curvilinear plateau model. When Ile, His and Leu levels were 10% below the requirement estimate, daily gain was reduced by 9%, 3% and 3%, respectively. The results of this study indicate that the Ile requirement estimate is lower than the current NRC requirement estimate, whereas the Leu and His requirements correspond to those proposed by the NRC.