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Where wildlife act as a reservoir of disease for domestic mammals, measures solely based on management of either in isolation are unlikely to resolve the problem. Many such diseases can have serious economic implications for farmers and the economy and their management can present considerable challenges. Traditionally, wildlife populations have been culled in attempts to reduce the risks of disease transmission to livestock (e.g. bovine tuberculosis in European badgers and brushtail possums). However, this may be both undesirable and potentially counter-productive in some circumstances. Consequently, in recent years increasing attention has focused on changing livestock husbandry and farm management practices so as to reduce risks of disease transmission from wildlife to livestock. Here we present a brief review of husbandry and farm management practices that may influence disease transmission risks from wild to domestic mammals, with particular attention to bovine tuberculosis in the UK. We conclude that the manipulation of farming practices could potentially make a significant contribution to disease risk management. However, there are currently scant empirical data on risk reduction methods and further information will undoubtedly be required to inform husbandry best-practice.
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.
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.
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.
Following the discovery of low serum copper (Cu) concentrations in 9-month-old beef calves at pasture in autumn (50% of animals had values <7·5 μmol/l), genetic variation in serum Cu concentration was studied in an experimental Angus herd in New Zealand, monitoring at intervals from about 7 to 17 months of age. The study was initiated in autumn when animals were supplemented with zinc (Zn) salts (to protect against liver injury from toxin-producing facial eczema spores on the pasture), and later in the production year after Cu supplementation but without Zn supplementation. Heritabilities of Cu concentration were estimated in 837 calves from six calf crops, the progeny of 47 sires, using restricted maximum likelihood procedures with an animal model. Correlations between Cu concentration and Zn concentration were also estimated, along with correlations between Cu concentration and 6-month, 9-month and yearling live weights. The heritability estimate for Cu concentration at all times outside the autumn Zn supplementation period was 0·28±0·08 (between-animal repeatability, 0·30±0·05), and the heritability estimates for autumn Cu concentration and Zn concentration were 0·35±0·11 and 0·26±0·13, respectively. The genetic and environmental correlations between autumn Cu concentration and Zn concentration were ?0·29±0·31 and 0·15±0·11, respectively, suggesting antagonistic effects between Zn and Cu only at the genetic level, with a net (phenotypic) correlation of 0·02±0·06. Genetic correlations between Cu concentration (outside the autumn season) and 6-month, 9-month and yearling weights ranged from 0·15±0·15 to 0·17±0·16. It was concluded that serum Cu and Zn concentrations in calves were heritable traits under the grazing conditions encountered, and that index selection to increase live weights and Cu concentrations could be applied if desired.
The aim of this study was to assess the potential consequences of selection for less aggressive or active animals during handling by estimating genetic correlations between different criteria of temperament and Limousin heifer breeding traits. Data consisted of the records collected from 1992 to 2004 at the progeny test station of Limousin AI sires. Six traits recorded during the same behavioural test – the so-called docility test – were considered to describe the heifer's temperament: aggressiveness against the handler, running time and number of escapes per minute of test period in presence or absence of the handler and a synthetic docility score accounting for the five previous components. Eight breeding traits were also considered simultaneously in the joint analysis with the five elementary temperament components: weights at 12 months and after calving (for measuring heifer growth), age at first observed oestrus (for measuring puberty) and fertility (for measuring heifer reproductive performance), calving ease score and pelvic opening (for measuring calving performance), maternal behaviour at calf's birth and milk yield (for measuring the suckling ability of the primiparous cow). REML (co)variance estimates were derived using linear multitrait sire models. Estimates of heritability were in the range of values given in the literature. Estimates of genetic correlation between temperament traits indicated that, genetically, aggressive animals also attempt to escape a lot. Consequently, their elimination will reduce both working risk and handling time for the breeder. Genetic correlations between temperament traits and breeding traits ranged from zero to favourable estimates and confirmed the very few results of the literature indicating a slight trend of less fearful heifers also being more productive, mainly because of a higher reproduction and calving performance, and, to a lesser extent, because of higher maternal abilities such as behaviour at calf's birth and milk yield.
Gene banks are usually used for storing general genetic variability of endangered living populations but can be also used for storing alleles of a particular locus that are being eradicated through artificial selection programmes. In such scenarios gene banks would allow future re-introduction of one or more of the alleles being eradicated (and the associated diversity) into living populations. Frequencies within the bank for the locus of interest should have pre-determined target values. In this study, an algorithm is derived to obtain the optimal contributions of all candidate donors to achieve the target frequencies of the removed alleles in the bank while maintaining at the same time genetic variability in other loci unlinked to those targeted in the eradication programme. The efficiency of the algorithm is tested using the case of gene banks storing prion protein alleles currently disfavoured in scrapie eradication programmes (i.e., the AHQ, ARH, ARQ and VRQ alleles). Results showed that the algorithm was able to find the combinations of candidate contributions fulfilling different objectives regarding target frequencies and restrictions on coancestry. The most important factors influencing the optimal contributions were the allelic frequencies and the levels of diversity (coancestry) of the living population. Heterozygotes were favoured over homozygous individuals as, for a given number of animals contributing to the bank, the use of heterozygotes leads to lower levels of coancestry. Notwithstanding, almost all donors were sampled when restrictions on the global genetic diversity to be stored were severe.
The present study was conducted to investigate the effects of ghrelin on gastric acid and pepsin secretion, as well as the mRNA expression of gastrin, somatostatin (SS) and receptors for growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in gastric mucosal cells in vitro. Gastric mucosal cells were isolated from 5-week-old weanling piglets and exposed for 4 h to 3×10−2, 3×10−1, 3, 3×10 and 3×102 nmol/l of h-ghrelin, respectively after 30-h incubation in DMEM/F-12. Pepsin activity in culture medium, cell viability and H+-K+-ATPase activity, as well as mRNA expression of gastrin, SS, GHR and IGF-1R in gastric mucosal cells were determined as response criteria. The experiment was repeated three times. Ghrelin significantly (P<0·05) increased H+-K+-ATPase activity of gastric mucosal cells at 3×10−1, 3 and 3×10 nmol/l of h-ghrelin. However, no significant changes were observed either in pepsin activity or the cell viability after ghrelin treatment. The mRNA expression of gastrin and SS was significantly increased in gastric mucosal cells exposed to h-ghrelin at 3×10−1 and 3 nmol/l (P<0·05). H-ghrelin significantly increased IGF-1R but not GHR mRNA expression at 3×10−1, 3 and 3×10 nmol/l of h-ghrelin (P<0·05). Ghrelin acts on gastric mucosal cells from weanling piglets to regulate the H+-K+-ATPase activity and mRNA expression of gastrin, SS, and IGF-1R in vitro.
Six ruminal cannulated Texel sheep were used to assess the dose response and the effect of live yeasts (Levucell® SC, Saccharomyces cerevisiae CNCM I-1077) on the prevention of induced ruminal latent acidosis. The sheep received, in a replicated 3×3 Latin-square design, an acidotic diet (wheat +lucerne hay, 60:40 (dry matter (DM) basis); starch: 410 g/kg DM) without yeast (control group; L0 treatment), supplemented with 0·2 g/day yeast (4×109 colony-forming units (c.f.u.) per day corresponding to producer recommendations; L1 treatment) or with 2 g/day yeast (4×1010 c.f.u. per day; L10 treatment). The following measurements were carried out: food intake, ruminal pH, ruminal volatile fatty acids (VFA), lactate and ammonia (NH3) concentrations, protozoal and lactate-utilizing bacterial counts, relative proportions of two main bacteria implicated in lactate metabolism (a lactate-producing species, Streptococcus bovis, and a lactate-utilizing species, Megasphaera elsdenii) using specific 16S-rRNA-targeting oligonucleotide probes, activities of lactate dehydrogenase (LDH) and of polysaccharidases involved in plant cell wall (xylanase, carboxymethylcellulase) and starch (amylase) degradation. The acidotic diet (L0) induced a butyric (12 mol per 100 mol total VFA) rather than lactic (<4 mmol/l) ruminal latent acidosis. Ruminal pH, fermentative patterns, lactate-metabolizing bacteria (concentration, LDH activity) and polysaccharidase activities were similar between treatments (P>0·1). Yeast supplementation tended to increase ruminal protozoal population (P<0·1) and intake of animals (P<0·1). The recommended yeast concentration (L1) was sufficient to ensure these effects. The yeast's action may differ according to the nature and function of the micro-organisms involved and the type of fermentative pattern favoured (protozoa/butyrate v. lactate-metabolizing bacteria/lactate and propionate) during ruminal acidosis in sheep.
An in vivo experiment was conducted to examine changes in fermentation end-products in the gastro-intestinal tract (GIT) of weaning piglets by the inclusion of fermentable carbohydrates in the diet. The experiment was repeated in three replicates of 36 piglets. Piglets were raised free of antibiotics and creep feeding prior to weaning at 4 weeks of age. Each replicate was conducted over a period of 10 days. The piglets were offered one of two dietary treatments: control diet (CON), and fermentable carbohydrate enriched diet (CHO); and were subjected to one of the two fasting treatments (i) fasting for 2 days in the beginning of the experimental period and (ii) non-fasting. Piglets were slaughtered on the 1st, 4th and 10th day of each period. Digesta samples were collected from: first half of small intestine, second half of small intestine, caecum, and colon. The dry matter, volatile fatty acid (VFA) profile, and ammonia concentrations were analysed. Food intake, growth and food conversion ratio were also recorded. There were no differences in production performances such as growth and food conversion ratio (FCR) between the treatment groups. Concentrations of VFA were significantly higher, while ammonia concentration was significantly lower in the CHO group compared to the CON group in different fermentation sites within the GIT (P<0·001), and on different slaughtering days (P<0·05). Fasting had no effect on fermentation end-products. This study concludes that the addition of fermentable carbohydrates of varying fermentabilities stimulated carbohydrate fermentation, with reduction in protein fermentation along the different parts of GIT studied, in weaning piglets.
The objective of this work was to determine the rumen fermentation characteristics of maize land races used as forage in central Mexico. In vitro gas production (ml per 200 mg dry matter (DM)) incubations were carried out, and cumulative gas volumes were fitted to the Krishnamoorthy et al. (1991) model. The trial used a split-plot design with cultivation practices associated with maize colour (COL) as the main plot with three levels: white, yellow and black maize; growing periods (PER) were the split plots where PER1, PER2 and PER3 represented the first, second and third periods, respectively and two contrasting zones (Z1=valley and Z2=mountain) were used as blocking factors. The principal effects observed were associated with the maturity of the plants and potential gas production increased ( P<0·05) in stems (PER1=51·8, PER2=56·3, PER3=58·4 ml per 200 mg DM) and in whole plant (PER1=60·9, PER2=60·8, PER3=70·9 ml per 200 mg DM). An inverse effect was observed with fermentation rates in leaves ( P<0·01) with 0·061, 0·053 and 0·0509 (per h) and in whole plant ( P<0·05) with 0·068, 0·057, 0·050 (per h) in PER1, PER2 and PER3 respectively. The digestibility of the neutral-detergent fibre (NDF) decreased with maturity especially in leaves ( P<0·05) with values of 0·71, 0·67 and 0·66 g/kg; in rachis ( P<0·01) 0·75, 0·72, and 0·65 in PER1, PER2 and PER3 respectively. The NDF content in leaves in leaves (668, 705 and 713 g/kg DM for PER1, PER2 and PER3, respectively), stems (580, 594 and 644 g/kg DM) and, husk (663, 774 and, 808 g/kg DM) increased ( P<0·05) with increasing plant maturity, rachis were significantly different between periods ( P<0·01). The structure with the best nutritive characteristics was the husk, because it had the lowest fibre contents, especially in acid-detergent lignin, with values of 22·6, 28·6 and 37·6 g/kg DM in PER1, PER2 and PER3, respectively.
The effects of 1-h soaking, fermentation and phytase supplementation of a pig diet based on wheat and barley on ileal and total tract apparent digestibility in growing pigs fitted with a post valve T-caecum (PVTC)-cannula were studied. Eight animals in a two-period change-over design were used, subjecting four animals to each treatment (dry, soaked, microbial phytase supplemented or fermented diet). Acid insoluble ash was used as an indigestible marker for calculating apparent digestibility coefficients. Fermentation improved ( P<0·05) the ileal apparent digestibility coefficients of organic matter (OM), nitrogen and amino acids, while there was no effect of 1-h soaking and phytase supplementation. The total tract apparent digestibility coefficient of OM was also improved by fermentation. The ileal apparent digestibility coefficient of phosphorus (P) was higher for fermentation ( P<0·05) than for dry food and 1-h soaking. The total tract apparent digestibility coefficient of P was higher ( P<0·05) for treated food (soaked, fermented and supplemented with microbial phytase) compared with dry food. Fermentation improved ( P<0·05) the ileal apparent digestibility coefficient of calcium compared with dry and soaked food, and had no effect on the total tract apparent digestibility coefficient of calcium. Food inositol phosphates were affected by treatment ( P<0·05), with a reduction of P bound to inositol hexaphosphate (IP6) of 10% in the 1-h soaked food and of 80% in the fermented food. Degradation of IP6 in the gastro-intestinal tract of the animals was lower in the fermented food than in the other treatments. The content of neutral-detergent fibre in the food was reduced ( P<0·05) in the soaked and fermented food by 4% and 14%, respectively, compared with the dry food. In conclusion, fermentation of food can improve digestibility of OM, degrade IP6 and increase ileal digestibility of phosphorus, nitrogen and amino acids.
This experiment sought to establish the response to increasing levels of coconut oil (CO) supplementation with a fixed 0·50:0·50 forage:concentrate diet on intake, digestibility and methane (CH4) emissions. Sixteen continental cross beef heifers (mean starting weight 481±36 kg) were assigned randomly to one of four levels of CO; 0 g/day, 125 g/day, 250 g/day or 375 g/day in an incomplete (three periods) multiple (no. =4) Latin-square design experiment (no. =12 per treatment). A linear reduction in CH4 output occurred as the level of CO in the diet increased ( P<0·001) with the greatest reduction at the 375 g/day level (394, 341, 314 and 240 l/day for animals fed 0, 125, 250 and 375 g/day CO, respectively). As the level of CO increased dry-matter (DM) intake (DMI) decreased, however these differences were only statistically significant at the 375 g/day level ( P <0·001). The proportional reduction in CH4 output was greater than the proportional reduction in DMI and hence CH4 l/kg DMI decreased from 39·8 l/kg when no CO was given to 29·7 l/kg when 375 g/day CO was given. The addition of CO to the diet resulted in a significant decline in dry-matter digestibility (DMD) at the 375 g/day level (P<0·05). These data demonstrate that the inclusion of CO at levels from 0·013 to 0·045 of the dietary DM within a 0·50:0·50 silage and concentrate ration reduces CH4 production with no adverse effect on DMI or DMD up to the 250 g/day level (0·027 of dietary DM).
Genetic selection is well established as a means of improving productivity in pigs, but the effects of continued selection for increased performance on immunity are not well understood, nor are genetic relationships between performance and immunity. This study compared differences in the levels of a range of immune traits between lines of Large White pigs divergently selected for a number of productivity traits. Selection lines compared were high v. low lean growth under restricted feeding (31 high line v. 10 control v. 38 low line pigs), high v. low lean growth under ad libitum feeding (18 high line v. 10 control v. 19 low line pigs), and high v. low food intake (24 high line v. 26 low line pigs). Immune traits measured were total white blood cell numbers (WBC), and the numbers of leukocyte subsets: neutrophils, monocytes, eosinophils, lymphocytes, CD4+ cells, CD8α+ cells, B cells, γδ T cells and CD11R1+ Natural killer (NK) cells. CD4+, γδ T cells and CD11R1+ cells were subdivided into subpopulations that were positive or negative for the CD8α marker, and conventional CD8αhigh+ cytotoxic T cells were also determined. Pigs were tested under ad libitum feeding conditions from 14 to 24 weeks, and immune traits were assessed at ages 18 and 24 weeks. Line differences were estimated using residual maximum likelihood techniques. Consistent differences in immune trait levels were evident between pigs previously selected for high and low lean growth under restricted feeding: at age 24 weeks, high line pigs had higher basal levels of WBC (39·6 v. 27·8×106 cells per ml, s.e.d. 2·09, for high v. low line pigs) mainly explained by higher levels of lymphocytes (25·5 v. 17·3×106 cells per ml, s.e.d. 1·54, for high v. low line pigs) with increased numbers of CD8α+ cells (8·19 v. 5·15×106 cells per ml, s.e.d. 0·14) and CD11R1+ cells (5·23 v. 2·46×106 cells per ml, s.e.d. 0·43), predominantly the CD11R1+ CD8α? subpopulation ((3·20 v. 1·64×106 cells per ml, s.e.d. 0·11). High line pigs also had increased numbers of monocytes (2·64 v. 1·83×106 cells per ml, s.e.d. 0·35). Similar results were obtained at age 18 weeks. There were no consistent differences between divergent lines in pigs selected for lean growth under ad libitum feeding or food intake. This is the first report to demonstrate that selection for some aspects of performance can influence WBC and leukocyte subset numbers in pigs.
Flavan-3-ols are a class of flavonoids that are widely distributed in fruits and beverages including red wine and apples. Consumption of flavanoid-rich food has been shown to exhibit anti-microbial, anti-oxidative, anti-inflammatory, and immune-modulating effects. To test the nutritional effects of flavanols on mRNA gene-expression of inflammatory and apoptotic marker genes, piglets were given two flavanoids-rich feeding regimens: a low flavanoid standard diet (SD) was compared with diets enriched with 3·5% apple pomace (APD) or 3·5% red-wine pomace (RWPD). The influence on mRNA expression levels was investigated in different immunological active tissues and in the gastro-intestinal tract (GIT). The investigation took place from 1 week prior weaning to 19 days post weaning in 78 piglets. The expression of expressed marker genes was determinate by one-step quantitative real-time (qRT-PCR): TNFα, NFκB as pro-inflammatory; IL10, as anti-inflammatory; caspase 3 as apoptosis; cyclin D1 as cell cycle marker; and nucleosome component histon H3 as reference gene.
The feeding regimens result in tissue individual regulation of mRNA gene expression in all investigated organs. It was discovered that there were significant differences between the applied diets and significant changes during feeding time curse. Both pomace treatments caused a significant up-regulation of all investigated genes in liver. The effect on mesenterial lymph nodes and spleen was not prominent. In the GIT, the treatment groups showed a inhibitory effects on gene expression mainly in stomach and jejunum (NFκB, cyclin D1 and caspase 3). In colon the trend of caspase 3 was positive with the greatest change in the RWPD group.
In jejunum and stomach the cell cycle turn over was reduced, whereas in liver the cell turn over was highly accelerate. The influence on inflammatory marker gene expression is mainly relevant in stomach. It is presume that both flavanoid rich feeding regimens have the potential to modulate the mRNA expressions of inflammatory, proliferation and apoptotic marker genes in the GIT and piglet organs.
A serial slaughter trial was carried out to examine the developmental change of physical and chemical body composition in pigs highly selected for lean content. A total of 48 pigs (17 females and 31 castrated males) were serially slaughtered and chemically analysed. Eight pigs were slaughtered at 20, 30, 60, 90, 120 and 140 kg live weight, (LW) respectively. The carcass was chilled and the left carcass side was dissected into the primal carcass cuts ham, loin, shoulder, belly and neck. Each primal carcass cut was further dissected into lean tissue, bones and rind. Additionally, the physical and chemical body composition was obtained for the total empty body as well as for the three fractions soft tissue, bones and viscera. Viscera included the organs, blood, empty intestinal tract and leaf fat. The relationship between physical or chemical body composition and empty body weight (EBWT) at slaughter was assessed using allometric equations (log10y=log10a+b log10 EBWT). Dressing percentage increased from 69·4 to 85·2% at 20 to 120 kg and then decreased to 83·1% at 140 kg LW, whereas percentage of soft tissue, bones and viscera changed from 23·5 to 33·0%, 10·1 to 6·3% and 14·7 to 10·3%, respectively, during the entire growth period. Substantial changes in proportional weights of carcass cuts on the left carcass side were obtained for loin (10·5 to 17·5%) and belly (11·3 to 13·8%) during growth from 20 to 140 kg. Soft tissue fraction showed an allometric coefficient above 1 ( b=1·14) reflecting higher growth rate in relation to the total empty body. The coefficients for the fractions bones and viscera were substantially below 1 with b=0·77 and 0·79, respectively, indicating substantial lower growth relative to growth of the total empty body. Lean tissue allometric growth rate of different primal cuts ranged from b=1·02 (neck) to 1·28 (belly), whereas rates of components associated with fat tissue growth rate ranged from b=0·62 (rind of belly) to 1·79 (backfat). For organs, allometric growth rate ranged from b=0·61 (liver) to 0·90 (spleen). For the entire empty body, allometric accretion rate was 1·01, 1·75, 1·02 and 0·85 for protein, lipid, ash and water, respectively. Extreme increase in lipid deposition was obtained during growth from 120 to 140 kg growth. This was strongly associated with an increase in backfat and leaf fat in this period. Interestingly, breeds selected for high leanness such as Piétrain sired progeny showed an extreme increase in lipid accretion at a range of LW from 120 to 140 kg, which indicates that selection has only postponed the lipid deposition to an higher weight compared with the normally used final weight of 100 kg on the performance test. The estimates obtained for allometric growth rates of primal carcass cuts, body tissue and chemical body composition can be used to predict changes in weight of carcass cuts, determine selection goals concerning lean tissue growth, food intake capacity, etc. and generally as input parameters for pig growth models that can be used to improve the efficiency of the entire pig production system for pigs highly selected for lean content.
The experiment was undertaken to quantify the α and γ-tocopherols accumulation in muscle and backfat from Iberian pigs given food free-range as affected by the time of free-range feeding or the weight gained during the fattening in free-range. Pigs were given their food in a free-range production system with pasture and acorns (Quercus rotundifolia) for different periods of time: 46 days (free-range 3), 83 days (free-range 2) and 111 days (free-range 1). A control was given food free-range for 0 days. In addition another experiment was developed to determinate the effect of the the weight gained on the tocopherols accumulation at a similar period of time (111 days) given food free-range: one group gained 68·7 kg of weight (free-range A) and the other 43·6 kg (free-range B). The concentration of γ-tocopherol significantly (P<0·0001) increased after 83 days of feeding in the longissimus dorsi (LD) and biceps femoris (BF) muscles, and after 111 days in the inner and outer backfat layers. The concentration of α-tocopherol was not statistically affected by the days of free-range feeding in any case. Iberian pigs that put on more weight had significantly (P< 0·0001) higher concentration of α and γ-tocopherols in the inner and outer backfat layers, and α-tocopherol in the BF muscle than those given food free-range B. However, no differences were detected in the proportion of α-tocopherol in the LD and γ-tocopherol in the LD and BF. The γ-tocopherol content of LD and BF muscles depending on the days of feeding were adjusted to linear and quadratic regressions (R2=0·8705 and 0·8697, respectively), while the outer and inner backfat layers were linear equations (R2=0·8480 and 0·8119, respectively). However, the γ-tocopherol concentration as affected by the weight gained in free-range showed in all tissues a linear and a quadratic trend that were adjusted to exponential responses. The α-tocopherol content was affected by the γ-tocopherol concentration in muscle and outer backfat layer. The tocopherol concentration (α and γ-tocopherols) in the backfat layers may discriminate better between the pigs of high quality that were given food free-range for a long period of time and those that stayed an intermediate period. However, to discriminate between the pigs on formulated food and those given food free-range, the quantification of the γ-tocopherol concentration in muscle could be a better indicator.
The objective of the present study was to test the reliability of the analysis method of the reflectance spectrum of fat in the zone of light absorption by carotenoid pigments developed in lambs to trace grass feeding in calves. Six feeding treatments were compared in suckling calves: ad libitum cocksfoot hay plus ad libitum concentrate or half level of ad libitum concentrate (HH and HL), ad libitum cut grass plus ad libitum concentrate or half level of ad libitum concentrate (GH and GL), ad libitum highland grazed grass plus ad libitum concentrate (PH); ad libitum medium quality cocksfoot hay plus dam's milk (C0). Groups HH, HL, GH, GL and PH were slaughtered at approximately 10 months of age, after 150 days of experimental feeding diet. C0 calves were slaughtered at the beginning of the experiment at approximately 6 months of age. The concentration of carotenoids was analysed by HPLC on diets and calves' plasma at slaughter. The reflectance spectrum of perirenal and subcutaneous fat were measured at slaughter and expressed as AVI units. Plasma carotenoid content was higher (P<0·05) in PH and GL calves than in HH, HL and GH calves. There was an effect (P<0·05) of feeding treatment and measurement site on AVI. Values obtained for perirenal fat were higher (P<0·05) than those obtained for subcutaneous fat. For plasma carotenoid content and for AVI values in both fat tissues there was no overlapping between hay-fed calves on the one hand and GL or grazing calves on the other hand. However, there was some overlapping between hay-fed calves and GH calves. For plasma carotenoid content, values for C0 calves overlapped with values of GH and GL calves. For both fat tissues AVI values of C0 calves overlapped with values of HH, HL, GH and GL calves. AVI of cut grass fed calves (GH and GL groups) increased linearly (P<0·05) with average daily grass intake for both tissues considered. AVI in subcutaneous fat tissue decreased linearly (P<0·05) with average daily concentrate intake but this relation was not significant for AVI in perirenal fat (P>0·05). Plasma carotenoid concentration and the reflectance spectrum of the fat in the zone of light absorption by carotenoid pigments could be used to trace grass feeding in calves. Results obtained in this study suggest that different fatty tissues could differ in their reliability and interest for traceability of grass-feeding, depending on the animal age and production system.