Twenty piglets (21 days, 7·8 kg live weight (LW)) were used in a 2×2 factorial to investigate interactions between lactose and inulin on intestinal morphology, microbiology and volatile fatty acid (VFA) production of the weanling pig. The piglets were offered the following diets for 6 days and then sacrificed: (T1) 150 g/kg lactose, (T2) 150 g/kg lactose +15 g/kg inulin, ( T3) 330 g/kg lactose, and ( T4) 330 g/kg lactose +15 g/kg inulin. Tissue samples were taken from the duodenum, jejunum and ileum for morphological measurements. Digesta samples were taken from the ileum, caecum and colon. There was an interaction ( P<0·05) between lactose and inulin in villous height in the jejunum. The inclusion of inulin at 150 g/kg lactose increased villous height compared with 150 g/kg lactose without inulin. However, inulin had no effect on villous height at 330 g/kg lactose inclusion. There was a linear relationship between food intake and villous height in the duodenum ( P<0·001, R2 =0·45) and the jejunum ( P< 0·01, R2 =0·25). The inclusion of 330 g/kg lactose increased ( P<0·05) total VFA compared with 150 g/kg lactose in the caecum and the population of lactobacilli in the caecum and colon ( P<0·1). There was an interaction ( P<0·05) between lactose and inulin for total VFA concentration in the colon. The pigs receiving 330 g/kg lactose had a higher total VFA concentration compared with pigs on 150 g/kg lactose. However, there was no difference between 150 g/kg and 330 g/kg lactose when the diets were supplemented with inulin. In conclusion, the inclusion of high dietary concentrations of lactose resulted in increased lactobacilli and short-chain fatty acid concentrations. The inclusion of inulin with low dietary concentrations of lactose resulted in improved intestinal health through a reduction of intestinal pH and increases in villous height.

These studies were conducted to determine whether dietary homoarginine, derived from guanidination of synthetic lysine, affects the measurement of apparent and true ileal amino acid digestibility in the pig and to determine the optimal ratio of o-methylisourea (OMIU) to free synthetic lysine in the guanidination reaction that produces homoarginine. In two preliminary experiments, specific amounts of lysine were weighed and added to a solution of 0·6 mol/l OMIU to produce OMIU to free synthetic lysine ratios of 2:1, 1·5:1, 1·4:1, 1·3:1, 1·2:1, 1·1:1 and 1·0:1. The mixture was incubated at a pH of 10·5 and a temperature of 20±1°C for 6 days. The highest yield of homoarginine (proportionately 0·995) was produced with an OMIU to free synthetic lysine ratio of 1·5:1. The serum concentrations of homoarginine and lysine were measured in two test pigs at various times after consuming a single meal containing either homoarginine or lysine. Blood samples were taken before and 0·5, 1·5, 2·5, 4·5, 6·0, 7·5, and 11·5 h after feeding. Thirty minutes after feeding the homoarginine-containing diet, the homoarginine concentration in serum was 0·013 mmol/dl, and increased to a maximum of 0·031 mmol/dl 1·5 h after feeding. Thirty minutes after feeding the lysine-containing diet, the serum lysine concentration was 0·011 mmol/dl and also reached its maximum concentration of 0·025 mmol/dl 1·5 h after feeding. The timing of the changes in concentration of homoarginine and lysine related to feeding were similar, which suggests that homoarginine is absorbed and metabolized in a similar manner to lysine. Six Large White×Landrace barrows, weighing 68·5±3·5 kg and fitted with a simple T-cannula at the distal ileum as well as a jugular vein catheter, were used to determine the effects of homoarginine on endogenous amino acid flows and apparent and true ileal amino acid digestibility. The experimental design was a doubly replicated 3×3 Latin-square design with the three treatments consisting of a lysine-free, zein-based diet and jugular infusion of a lysine solution; a lysine-free, zein-based diet supplemented with homoarginine; and a lysine-free, zein-based diet supplemented with l-lysine. There were no significant differences in endogenous ileal lysine flow for pigs receiving the different treatments (396·6, 407·6, and 360·4 mg/kg DMI, respectively, P=0·71). In addition, with the exception of phenylalanine (P=0·04), there were no significant differences (P>0·10) in the apparent and true ileal digestibility of crude protein and amino acids among the three treatments. Therefore, it would appear that the presence of dietary homoarginine, derived from guanidination of synthetic lysine, does not affect endogenous amino acid losses or the digestibility of crude protein as well as most amino acids. These results are therefore supportive of the use of the homoarginine method as a means of measuring true ileal lysine digestibility.

The impact of parasites on domestic livestock is well known. It is also clear that parasites have the potential to reduce reproductive success and survival at the individual level in wild animal populations (often through effects on body condition). However, the degree to which these impacts can regulate populations is difficult to determine because of the logistics of conducting the necessary experimental manipulations of either hosts or parasites. In addition, the relative importance of this mechanism compared to other regulatory factors such as predation and competition for food resources has not been quantified. Studies that have investigated the impact of parasites on wild mammals are reviewed and the merits of cross-sectional sampling and experimental approaches are presented. Finally, evidence for parasite mediated population regulation in wild mammals is examined and the need to develop experimental approaches that address this mechanism and its interaction with other regulatory processes is discussed.

The data sets consisted of field performance data from 54 848 purebred and 16 175 crossbred animals (Czech data set, CZ) and 16 610 purebred and 9 228 crossbred animals (Slovak data set, SK). Animals from the following breeds were included: Duroc, Hampshire, Piétrain, sire line of Large White (CZ) or Yorkshire (SK), Czech Meat pig (CZ) or Slovak Meat pig (SK), Belgian Landrace (SK). Two-trait animal models were calculated for average daily gain from birth to the end of the field test (ADG) and lean meat content (LM, only in CZ) or backfat thickness (BF, only in SK). The models included additive breed and breed heterotic effects. Piétrain was the breed with the highest LM and the lowest BF. The additive genetic breed effect was about 1·5% LM (CZ) in comparison with Large White or −0·4 mm BF (SK) in comparison to Yorkshire. The sire line of Large White (CZ) or the Yorkshire breed (SK) clearly exceeded all the remaining sire breeds in ADG (on average by 30 to 50 g/day). There was a clear tendency to negative heterosis in LM in all crossbred combinations (CZ). In BF, heterotic effects between −0·2 mm and +0·3 mm were estimated, mostly not being significant (SK). The estimates of the heterotic effects for ADG were positive throughout. Higher values up to 40 g/day (7%) were observed in the Czech data set. Though heterotic breed effects are of some importance especially for ADG, their inclusion in the equations for breeding value estimation will have only a minor impact on the predicted breeding values.

This study investigated the effects of 100 g/kg increments of crude protein (approx. 250 (P25) to 550 (P55) g/kg of crude protein) in paired iso-energetic diets on the growth performance of the juvenile Australian short-finned eel (1·83 (s.e. 0·01) g average wet weight). The highest growth response was obtained with treatment P45 followed by P35, P55 and P25. It appeared that food efficiency ratio (FER) increased with increasing crude protein content in low energy diets (treatments P25 and P35). However, 100 g/kg increase in dietary crude protein content (from 450 to 550 kg crude protein per kg diet) in high energy diets resulted in lower FER for treatment P55 than for the treatment P45. The protein efficiency ratio (PER, %) was higher in low protein:low energy diets (treatments P25 and P35) than that of high protein:high energy diets (treatments P45 and P55). The protein productive values (PPV, %) for treatments followed a similar trend to PER in this experiment. The lowest PPV was obtained by the treatment P55 and it was significantly different from that of the other three treatments. A proportional increase in dietary crude protein content in paired iso-energetic diets did not significantly change the whole body protein content. However, a small increase in whole body protein content with increasing dietary crude protein in each group was detected. In conclusion, the present study showed protein sparing effects of lipids and carbohydrates in the diets of the short-finned eel. Further studies specifically investigating the effects of dietary carbohydrate to lipid ratios at different protein levels would improve diet formulation and reduce nutrient impact in intensive recirculation systems.

The objective of this study was to determine the proportion of forage in the diet which would maximize duodenal flow of unsaturated fatty acids in beef steers supplemented with linseed oil. A second objective was to determine how diets differing in forage content, but equal in nitrogen (N), energy and lipid supply, would affect the duodenal flow of C18:1 and conjugated linoleic acid (CLA) isomers. Eight Hereford×Friesian steers (533±13·6 kg), prepared with rumen and duodenal cannulae were offered one of four forage:concentrate (F:C) ratios: F80C20; F60C40; F40C60 and F20C80 on a dry-matter (DM) basis. All diets were offered at 0·013 body weight and designed to be isonitrogenous and isoenergetic with total lipid made up to 0·06 DM intake with linseed oil. The experimental design was a replicated incomplete 4×4 Latin square with three periods. Increasing the concentrate component in the diet from 0·20 to 0·60 reduced rumen pH from 6·58 to 6·37 and caused a small but significant shift in volatile fatty acid molar proportions, decreasing the non-glucogenic ratio. Rumen ammonia-nitrogen concentration was also significantly reduced with increasing concentrate, from 156·8 to 101·0 mg N per l on F80C20 and F20C80, respectively. Microbial nitrogen (MN) and the efficiency of microbial protein synthesis was significantly elevated as forage level decreased from 51·6 to 72·4 g/day and 17·2 to 27·3 g MN per kg organic matter apparently digested in the rumen, respectively for F80C20 and F20C80. Intake and duodenal flow of C18:1n-9 and C18:2n-6 were significantly higher with increasing concentrate level in the diet whereas C18:3n-3 intake and flow was not different, averaging 143·6 and 6·37 g/day, respectively. There were no differences in the flows of total C18:1 trans or CLA (47·7 and 1·79 g/day, respectively) across the diets. However, although not significantly different in duodenal flow there were trends (P<0·1) for an increasing proportion of trans-10 and a decreasing proportion of trans-11 when increasing the concentrate in the diet. Biohydrogenation of C18:2n-6 decreased from 0·91 to 0·85 when increasing concentrate in the diet from 0·20 to 0·40 but further increases had no effect. F:C ratio had little effect on the flow of unsaturated fatty acids, C18:1 trans and CLA to the duodenum of beef steers, and this may relate to the ability of the rumen to buffer the large changes in concentrate intake.

The objective of the first of three studies (experiment 1) was to evaluate the effects of supplementing the pregnant ewe diet with high levels of minerals for the final 4 weeks of gestation on lamb serum vitamin E and immunoglobulin G (IgG) concentration at 24 h post partum. Sixty ewes were allocated to one of two treatments (no. =30) and offered a basal diet fortified with 52 g of supplementary minerals/vitamins containing Ca, Mg, Na, P, Co, I, Mn, Se, Zn and vitamin E (M1) for the final 4 weeks of pregnancy or no mineral/vitamin supplement was added (C1). Immediately after birth, lambs were allocated to one of four treatments in a 2×2 factorial design with the factors being ewe treatment (± minerals) and colostrum origin (± minerals). Irrespective of the colostrum origin, the progeny of the mineral supplemented ewes had lower serum vitamin E and IgG concentrations and IgG absorption efficiency at 24 h post partum ( P <0·001). In a second study (experiment 2), 44 ewes were allocated to one of four treatments (no. =11) in week 13 of pregnancy and offered a basal diet in addition to one of the following mineral/vitamin fortifications: 0 g (C2), 52 g of a mineral supplement as in experiment 1 (M2), a supplement as in M1 but with iodine excluded (-I), iodine only offered at a rate (40 mg per ewe per day) equivalent to 52 g of minerals (IO). When iodine was offered either M2 ( P <0·01) or (IO) ( P <0·001) it resulted in the progeny having a reduced serum vitamin E concentration at 24 h post partum. The -I progeny had higher serum vitamin E concentrations at 24 h post partum than the progeny of treatments C2, M2 ( P <0·01) and IO ( P <0·001). In a third study (experiment 3) the effect of incremental levels of iodine supplementation on lamb serum vitamin E concentration was studied. Forty-eight ewes were allocated to one of four treatments (no. =12) and offered the following levels of supplementary dietary iodine: 0 mg (C3), 8·9 mg (LI), 17·7 mg (MI) or 26·6 mg (HI) for the final 6 weeks of pregnancy. There was a linear ( P <0·001) reduction in lamb serum vitamin E concentration as maternal iodine supplementation increased. We conclude that when ewes are offered high levels of iodine during the final 6 weeks of gestation their progeny are pre-programmed in utero to have a reduced ability to absorb colostral vitamin E. These findings support our earlier studies and provide further evidence of the need to reduce the current toxicity values for iodine. for the ewe in late pregnancy.

Decisions made by farmers may have large influences beyond the farm boundary, and for this reason they are often of interest to Government and the public. The process of adoption of new technologies and policies has received considerable academic attention over many years, and this has highlighted the rôle of social influences in decision-making. In addition a range of purely economic-based models of farmer decision-making have been developed in order to predict potential changes in agriculture and land use under future policy and market scenarios. Since the 1990s these traditional approaches to understanding decision-making have been supplemented by an increasing input from psychology. As a result of this work it is clear that farmers' decisions are influenced by a range of factors which may be grouped under six headings: socio-demographics of the farmer, psychological make up of the farmer, the characteristics of the farm household, structure of the farm business, the wider social milieu and the characteristics of the innovation to be adopted. This paper presents a short review of the quantitative methods that seek to integrate insights from economics and social science within theoretical frameworks derived from psychology. Suggestions for further work include more empirical study in farmer decision-making related to animal health and welfare, the rôle of the farmers' own health status in decision-making and the formal integration of economic and psychological variables in simulation models.

A model able to predict missing test day data for milk, fat and protein yields on the basis of few recorded tests was proposed, based on the partial least squares (PLS) regression technique, a multivariate method that is able to solve problems related to high collinearity among predictors. A data set of 1731 lactations of Sarda breed dairy Goats was split into two data sets, one for model estimation and the other for the evaluation of PLS prediction capability. Eight scenarios of simplified recording schemes for fat and protein yields were simulated. Correlations among predicted and observed test day yields were quite high (from 0·50 to 0·88 and from 0·53 to 0·96 for fat and protein yields, respectively, in the different scenarios). Results highlight great flexibility and accuracy of this multivariate technique.

Mixing of commercial pigs frequently leads to intense aggression. Considerable phenotypic variation exists between individuals and selection against aggressiveness may offer a long-term reduction in aggression without incurring additional costs to the primary producer. The genetic contribution to aggressiveness was quantified in this study using the number of skin lesions as an indicator of involvement in aggression. A sample of 1132 pigs were mixed at an average weight of 27·9 (s.d. 4·6) kg into 96 pens on a commercial sire line nucleus unit. Post-mixing aggressiveness of pigs was assessed using the lesion score (LS) approach. Growth rate, between 27·9 and 91·9 kg, and backfat depth at 91·9 kg were recorded for a subsample of 658 pigs. With a pedigree file of 1947 animals, a heritability of 0·22 was estimated for the LS trait. No significant genetic or phenotypic correlations were found between LS and growth rate or backfat depth, but standard errors of estimates were large. The response to selection, when all selection pressure was placed on the LS trait, was a 25% reduction in LS per generation. It is therefore technically possible to select for a reduced LS without substantially inhibiting genetic progress in growth rate or backfat depth through antagonistic genetic relationships.

Preference testing of two foods provides a means of assessing the relative value an animal places on the foods. Two experiments examined the relative choice of grass and maize silages by lactating dairy cows, and investigated whether protein supplementation, concentrate level or milk yield level of cow influenced this choice. In experiment 1, 16 cows including eight high (30 kg/day) and eight low (17 kg/day) yielding (milk level, ML) cows were offered a low (171 g/kg dry matter (DM)) or a high (300 g/kg DM) crude protein (CP) concentrate in eight 2×2 Latin squares. In experiment 2, four cows were offered a low (112 g/kg DM) or a high (334 g/kg DM) CP content of concentrate at a low (3·5 kg/day) or high (7 kg/day) concentrate level (CL) in a 4×4 Latin-square design.CP of concentrate did not influence the proportion of grass silage to maize silage eaten in either experiment. Also, neither ML of cows (experiment 1) nor CL (experiment 2) affected proportions of the two silages eaten. The mean proportions selected were 0·88:0·12 and 0·52:0·48 for grass and maize silages in experiments 1 and 2 respectively, which reflected differences between experiments in the digestibilities of the silages, and indicated that digestibility may be an important factor influencing the choice of silages.The CP, CL and ML treatments produced significant responses in silage and total DM intakes. Feeding behaviour studies showed the responses to CP were associated with differences in meal size, which is a function of duration of each meal and rate of intake. The number of meals taken per day was similar for all treatments and averaged 8·0 and 8·1 for experiments 1 and 2 respectively.It was concluded that whilst lactating cows modified their feeding behaviour in response to the diets available, there was no evidence they modified the proportions of the two silages selected in order to meet a target protein content in the total diet. It would appear therefore that other factors, of which digestibility may be important, have a higher priority in choice.

Tree leaf meals (TLM) are increasingly used in the tropics to feed pigs. The nutritive value of the TLM of cocoyam (Xanthosoma saggitifolium), mulberry (Morus alba) and Trichanthera gigantea, their effect on the digestive tract and their fermentation rate in the large intestine, were determined in adult sows given diets containing 150 or 300 g TLM per kg. The TLM contained from 8·5 to 12·0 MJ digestible energy per kg dry matter (DM) and from 60 to 125 g digestible protein per kg DM. The digestibility was not affected ( P>0·05) by their rate of incorporation in the diet. The apparent ileal protein digestibility of the diets containing 300 g TLM per kg was also determined by the slaughtering method. It reached 80% for the basal diet and 54, 70 and 74% for the Trichanthera-, mulberry- and cocoyam-based diets, respectively. No diet effect ( P>0·05) was observed on the weight and length of the gastro-intestinal tract, with the exception of a heavier caecum in sows given the Trichanthera-based diet ( P<0·01). The pH of the gastric fluid of these sows was also higher ( P<0·001). The fermentation of the dietary fibre in the large intestine was evaluated by the gas technique using syringes. The cocoyam leaves presented the highest amount of total gas produced after fibre fermentation ( P<0·001). The ranking order of gas production was identical to that observed for the digestibility coefficients: Trichanthera <mulberry <cocoyam. In conclusion, TLM can represent up to 0·3 of a diet for sows. Their use in sow nutrition may be considered in tropical regions where protein sources are scarce.

The effect of dietary protein supply, as manipulated by both crude protein content and/or substitution of existing ingredients, mainly soya (SOYA), with the more digestible dried skimmed milk powder (DSMP), and the consequences of removing in-food antimicrobial growth promoters (AGPs) on the performance and risk of post-weaning enteric disorders (PWED) in newly weaned pigs was investigated. Pigs weaned at 28·7±3·45 days of age (no. =49) were individually housed in an environmentally controlled room and assigned to one of seven dietary treatments; a 3×2 factorial combination of dietary protein content (130, 180 and 230 g crude protein (CP) per kg) and main protein source (DSMP and SOYA), plus an additional control containing 230 g CP per kg, DSMP and in-food AGPs (ZnO, CuSO4 and avilamycin). Individual food intake, faecal score (FS), cleanliness score (CS) and health score (HS) were taken daily, and live weight and faecal samples were taken on days 0, 4, 7, 11, 12, 13 and 14. All animals were slaughtered on day 14 to examine variables describing aspects of gastro-intestinal health. Increasing CP content and the removal of AGPs both led to a significant increase in faecal fluidity and contamination although there was no effect on HS. There was no effect of DSMP inclusion on FS, CS or HS. Increasing CP content led to an increase ( P<0·05) in the number of coliforms in faecal and proximal colon (PC) samples taken at slaughter and a decrease ( P<0·01) in the lactobacilli to coliform ratio (L:C) in the PC. Increasing CP content had no effect on average daily food intake (ADFI) but led to improvements in average daily gain (ADG) ( P<0·001) and food conversion ratio (FCR) ( P<0·001) over the whole trial period. The inclusion of DSMP had no effect on performance during the 1st week, but animals on the DSMP diets had improved ADG ( P<0·05) and FCR ( P<0·01) compared with those on the SOYA diets in the 2nd week. The inclusion of AGPs increased ADFI ( P<0·05) and ADG ( P<0·05) but had no effect on FCR over the whole trial period. The results indicate that in the absence of AGPs both growth performance and the risk of PWED increased as protein supply was increased. The increased risk of PWED was associated with an increased fluidity of faeces, a reduction in the L:C ratio and an increase in intestinal pH. Consequently, it is important to balance the trade-off between maximizing performance and minimising the risk of PWED through manipulating protein supply, particularly in an environment where AGPs are no longer permitted.

The objective of this study was to investigate the effect of orally administered spermine at various doses on intestinal maturation in sucking piglets. Thirty-six 11-day-old sucking piglets were assigned randomly to one of six treatments to receive via a stomach tube 0, 0·1, 0·2, 0·3, 0·4, or 0·5 mmol spermine per kg live weight (LW) per day for 3 days. At day 14 of age, duodenum, jejunum and ileum were obtained for biochemical and morphological analysis. Increasing the dose of orally administered spermine increased intestinal weight (linear effect, P<0·01), mucosal weight (linear effect, P<0·05), and mucosal protein, DNA and RNA contents of the duodenum (linear effect, P≤0·01) and jejunum (linear effect, P<0·01). Elevating spermine doses also enhanced (linear effect, P≤0·02) the specific activities of maltase and sucrase but decreased (linear effect, P<0·01) lactase specific activity in the jejunum and duodenum. Furthermore, augmenting oral doses of spermine increased crypt depth and villus width but reduced villus height in the jejunum (linear effect, P<0·05) and duodenum (linear effect, P<0·01). For most measurements, the effects were observed at the oral spermine doses of 0·3 to 0·5 mmol/kg LW per day. Collectively, the results show that oral administration of optimal doses of spermine to 11-day-old sucking piglets induces precocious intestinal maturation and promotes intestinal growth.

The relationship between stockperson behaviour, measured as verbal and physical interactions with the dairy cows (no.=210), during milking and the subsequent milk yield obtained was examined. The numbers of steps and kicks made by the cows during milking was recorded. The behaviour of two stockteams, each consisting of two stockmen, were recorded over 10 weekend sessions. The two teams varied in the types of interactions and when the stockteam that performed more positive interactions worked with the cows (team A), the cows had a significantly higher milk yield (P<0·05) although this difference was small (17·54 v. 17·44 kg). When team A was milking the cows also stepped and kicked on the platform significantly more (P<0·05) compared with team B. The results also indicated that while each stockteam tended to interact with the same cows each session, different stockpersons interacted with different cows. These findings highlight the importance of the rôle of the stockperson in milk output and dairy cow behaviour in a commercial setting.

Advancing maturity of forage maize is associated with increases in the proportion of dry matter (DM) and starch and decreases in the proportions of structural carbohydrates in the ensiled crop. Three maize silages (286 (low, L), 329 (medium, M) and 379 (high, H) g DM per kg fresh weight) plus a concentrate formulated to give isonitrogenous intakes were offered to Holstein-Friesian steers fitted with a cannula in the dorsal sac of the rumen and a ‘T’ piece cannula in the proximal duodenum in an experiment with a cross-over design that allowed four collection periods. Nutrient flow to the duodenum was estimated using chromium-EDTA. Steers consumed approximately 0·6 kg DM per day less of diet L compared with the other two diets (P=0·026), resulting in less DM being digested (P=0·005) but digestibility did not differ between diets. Similar results were obtained for organic matter. There were no differences between diets in the intake or digestibility of neutral-detergent fibre. Intake, duodenal flow and faecal output of starch were greater for steers offered diets M and H compared with those given diet L (P<0·05). In all diets rumen digestion contributed to over 90% of total digestion of starch, although rumen digestibility declined significantly with advancing maize maturity (P=0·002). Molar proportions of acetic acid were higher in diet H (P<0·05) whilst proportions of propionic acid and n-butyric acid were higher in diets M and L. There were no significant differences between diets in mean rumen pH or ammonia concentrations. Mean circulating concentrations of insulin were higher (P=0·009) in cattle given diets L and M compared with diet H. There were no differences between diets in the mean circulating concentration of growth hormone, or the frequency, amplitude and duration of growth hormone pulses, or the mean circulating concentrations of IGF-1. Changes in forage composition that accompany advancing maize maturity affect overall silage digestion and circulating concentrations of insulin.

Digestion and absorption of carotenoids were studied in sheep given, twice daily, fresh red clover. Digestive fluxes were measured in six sheep cannulated in the rumen, duodenum and ileum using the double marker technique. Another five sheep were fitted with catheters allowing nutrient net flux measurements across the portal-drained viscera. Carotenoids in the red clover consisted of lutein (136 μg/g dry matter (DM)), epilutein (40 μg/g DM), trans-β-carotene (16 μg/g DM) and 13-cis-β-carotene (13 μg/g DM). Intake was 174, 52, 21 and 17 mg/day, and faecal excretion was 181, 25, 50 and 41 mg/day, for lutein, epilutein, trans- and 13-cis-β-carotene respectively, indicating net production of β-carotene in the digestive tract. The difference between duodenum and intake was positive for all carotenoids (30, 4, 43 and 37 g for lutein, epilutein, trans-β-carotene and 13-cis-β-carotene, respectively) suggesting net production and/or release of carotenes and xanthophylls by rumen microbes. Apparent digestibility in the small and large intestines was 0·18 and −0·05 for lutein, 0·30 and 0·29 for epilutein, 0·39 and 0·26 for trans-β-carotene, 0·53 and 0·21 for 13-cis-β-carotene. Only lutein and epilutein were recovered in arterial plasma, at a concentration of 14·3 and 10·8 μg/l, respectively. Their portal net appearance was not different from 0, suggesting that absorption occurred mainly via the lymphatic system.

The aim of this study was to investigate the possibility of improving the composition of goat meat, in terms of the fatty acid composition of the different fat deposits. For this purpose, we used two groups of 12 female goats each of which had recently undergone a double birth. The animals were maintained under semi-extensive conditions and trough-fed with a concentrate that was either non-supplemented or supplemented with 50 g/kg of polyunsaturated fatty acids (PUFA)-rich fat protected against ruminant metabolism. The kid goats born to each group were suckled by their dams and a representative sample of each was slaughtered at 45 days after birth. The milk produced by the dams receiving the fat-supplemented diet contained fat with a lower content of saturated fatty acids and a higher content of n-3 PUFA, trans-C18: 1 and CLA. The kid goats suckled by these dams grew faster and the legs of the carcasses presented greater muscular development compared with the non-fat-supplemented diet group. The cover, intermuscular and intramuscular fat presented a different fatty acid composition, with a higher proportion of n-3 PUFA, trans C18: 1 and CLA, while that of n-6 PUFA remained unchanged. The change in the lipid metabolism of the kid goats was made evident by the blood levels of certain biochemical parameters. We discuss the improvement in the quality of the meat obtained, taking into account the feeding strategy provided and the class of animal in question.

In stall-feeding conditions, food diversity has been shown to increase an animal's motivation to eat and its level of food intake. This effect has also been suggested, but not demonstrated, for free-grazing animals. In free-grazing conditions, however, animals may have to search for the preferred plant species and this may reduce their intake rate. Moreover, the management of diverse swards faces a risk of overgrazing the preferred species and undergrazing the less preferred species, leading to resource degradation. We investigated the effect of food diversity on foraging behaviour and intake in grazing sheep, in interaction with the type of diversity (conterminal monocultures v. mixtures) and management (two monocultures offered simultaneously v. successively over time). Five treatments were compared with five groups of five dry INRA 401 ewes for five periods, using a Latin-square design: LOL=grazing a monoculture of Lolium perenne cv. Herbie (L); FES=grazing a monoculture of Festuca arundinacea cv. Florine (F); STRIPS=grazing conterminal monocultures of L and F, 0·5:0·5 by ground area, with animals having a free choice between both species; TIME=grazing L from 16:00 to 09:00 h and F from 09:00 to 16:00 h; MIX=grazing an intermeshed mixture of L and F. Sward height was maintained at 9 cm. Each period comprised a 5-day adaptation subperiod followed by a 5-day measurement subperiod. Dietary choices and intake were measured using n-alkanes, and grazing time was assessed using the Ethosys® recording system. Intake rate was calculated as the ratio of intake to grazing time. Intake in the monoculture treatments were higher than predictions made for housed animals given similar forages ad libitum, demonstrating that sward conditions were favourable for the expression of voluntary intake in all treatments. Intake was higher in LOL than in FES, this result being consistent with predictions for stall-feeding conditions. There was no difference in diet composition, foraging behaviour and intake between the bispecific treatments (STRIPS, TIME and MIX). Intake was higher in the bispecific treatments than in LOL (1666 v. 1492 g digestible organic matter per day, P<0·001). Grazing time was higher in STRIPS and MIX than in LOL (420 and 430 min respectively v. 366 min, P<0·01). Dry ewes increase their intake when offered a choice of herbage species at pasture, this being mediated via an increase in grazing time rather than an increase in intake rate. There was no interaction with type of diversity or type of management.

It is well established that plant oils reduce milk saturated fatty acid content and enhance concentrations of conjugated linoleic acid (CLA) and trans C18:1 in milk fat, but there is increasing evidence to suggest that milk fat CLA responses are often transient and decline over time. It is probable that time dependent adaptations in ruminal biohydrogenation and changes in milk fatty acid composition to lipid supplements are, at least in part, related to the composition of the basal diet. To test this hypothesis, 18 Holstein cows were used in a continuous randomized block design to examine changes in milk fatty acid composition over time in response to plant oils included in diets of variable composition. Cows were randomly allocated to one of three basal diets containing (g/kg dry matter (DM)) maize silage (267) and concentrates (733) (diet C); maize silage (332), grass hay (148) and concentrates (520) (diet M), or grass hay (642) and concentrates (358) (diet H). Basal rations were offered for 21 days, after which diets were supplemented with 50 g sunflower per kg DM (diets C-S and M-S) or 50 g linseed oil per kg DM (diet H-L). Oils were included in all rations incrementally over a five day period (days 0–4), and responses to 50 g/kg DM of the respective oils were evaluated for 17 days (days 4 to 20). Milk fatty acid composition was intensively monitored from days −2 to 20. In contrast to the H-L diet, both C-S and M-S treatments decreased (P<0·05) DM intake, milk fat content and yield, while the C-S diet also reduced (P<0·05) milk yield. Milk fat cis-9, trans-11 CLA and trans-11 C18:1 contents were enhanced on the C-S and M-S treatments but the increases were transient reaching the highest concentrations between days 4 and 6 (cis-9, trans-11 CLA: 1·94 and 2·18 g per 100 g total fatty acids; trans-11 C18:1: 4·88 and 6·23 g per 100 g total fatty acids, respectively) but declined thereafter. In marked contrast, concentrations of cis-9, trans-11 CLA and trans-11 C18:1 in milk from the H-L diet increased gradually over time, responses that were maintained until the end of the experiment (2·89 and 7·49 g per 100 g total fatty acids, respectively).Decreases in milk fat cis-9, trans-11 CLA and trans-11 C18:1 after day 6 on the M-S and C-S diets were associated with concomitant increases in milk fat trans-10 C18:1 content reaching 7·22 and 18·62 g per 100 g total fatty acids on day 18, respectively, whereas concentrations of trans-10 C18:1 in milk on the H-L diet remained low throughout the experiment (0·70 g per 100 g total fatty acids on day 18). Furthermore, milk fat trans-11, cis-13 CLA, trans-11, trans-13 CLA and trans-12, trans-14 CLA contents were all enhanced on the H-L diet, while the M-S and C-S diets increased trans-8, cis-10 CLA, trans-10, cis-12 CLA and trans-9, cis-11 CLA concentrations. Across all diets, decreases in milk fat content were associated with increases in milk trans-10 C18:1, trans-10, cis-12 and trans-9, cis-11 CLA concentrations (r2=0·93, 0·88 and 0·89, respectively). In conclusion, the relative abundance of trans C18:1 and CLA isomers in milk fat were dependent on the composition of the basal diet, type of plant oil and duration of lipid supplementation, highlighting the challenges in developing nutritional strategies for the production of milk highly enriched with CLA over an extended period of time.