Behavioural adaptation of farm animals to environmental changes contributes to high levels of production under a wide range of farming conditions, from highly controlled indoor systems to harsh outdoor systems. The genetic variation in livestock behaviour is considerable. Animals and genotypes with a larger behavioural capacity for adaptation may cope more readily with varying farming conditions than those with a lower capacity for adaptation. This capacity should be exploited when the aim is to use a limited number of species extensively across the world. The genetics of behavioural traits is understood to some extent, but it is seldom accounted for in breeding programmes. This review summarizes the estimates of genetic parameters for behavioural traits in cattle, pigs, poultry and fish. On the basis of the major studies performed in the last two decades, we focus the review on traits of common interest in the four species. These concern the behavioural responses to both acute and chronic stressors in the physical environment (feed, temperature, etc.) and those in the social environment (other group members, progeny, humans). The genetic strategies used to improve the behavioural capacity for adaptation of animals differ between species. There is a greater emphasis on responses to acute environmental stress in fish and birds, and on responses to chronic social stress in mammals.

Differential gene expression analyses typically focus on departures across mathematical expectations (i.e. mean) from two or more groups of microarrays, without considering alternative patterns of departure. Nevertheless, recent studies in humans and great apes have suggested that differential gene expression could also be characterized in terms of heterogeneous dispersion patterns. This must be viewed as a very interesting genetic phenomenon clearly linked to the regulation mechanisms of gene transcription. Unfortunately, we completely lack information about the incidence and relevance of dispersion-specific differential gene expression in livestock species, although a specific Bayes factor (BF) for testing this kind of differential gene expression (i.e. within-probe heteroskedasticity) has been recently developed. Within this context, our main objective was to characterize the incidence of dispersion-specific differential gene expression in pigs and, if possible, providing the first evidence of this phenomenon in a livestock species. We evaluated dispersion-specific differential gene expression on ovary, uterus and hypophysis samples from 22 F2 Iberian × Meishan sows, where a total of 15 252 probes were interrogated. For each tissue, heteroskedasticity of probe-specific residual variances was evaluated by three pairwise comparisons involving three physiological stages, that is, heat, 15 days of pregnancy and 45 days of pregnancy. Between 2.9% and 37.4% of the analyzed probes provided statistical evidence of within-tissue across-physiological stages dispersion-specific differential gene expression (BF >1), and between 0.1% and 3.0% of them reported decisive evidence (BF >100). It is important to highlight that <8% of the heteroskedastic probes were also linked to differential gene expression in terms of departures among the probe-specific mathematical expectation of each physiological stage. This discarded the disturbance of scale effects in a high percentage of probes and suggested that probe-specific heteroskedasticity must be viewed as an independent phenomenon within the context of differential gene expression. As a whole, our results report a remarkable incidence of dispersion-specific differential gene expression across the whole genome of the pig, establishing a very interesting starting point for further studies focused on deciphering the genetic mechanisms underlying heteroskedasticity.

This work was part of a project designed to assess whether organic selenium (Se) can protect against the toxic effects of cadmium (Cd). A total of 300 1-day-old, as hatched, broilers were randomly distributed in four dietary treatments with five replicate pens per treatment. In T1 treatment, broilers were fed a diet with 0.3 mg/kg added Se, as Se-yeast, without added Cd; in T2, broilers were fed a diet with 0.3 mg/kg Se and 10 mg/kg Cd; in T3, broilers were fed a diet with 0.3 mg/kg Se and 100 mg/kg of Cd; and in T4 treatment broilers were fed a diet with 3 mg/kg Se and 100 mg/kg Cd. The Cd was added to diets T2, T3 and T4 as CdCl2. On the 4th and 6th week, two broilers per replicate pen were killed in order to obtain whole blood, liver, kidney and breast samples. Body mass, feed conversion ratio and mortality were assessed and haematological analyses were performed. Se and Cd levels in tissues were analysed by inductively coupled plasma mass spectrometry. Broilers supplemented with 0.3 mg/kg Se can tolerate low levels of Cd added to the diets, as there were no significant negative effects on the examined performance parameters, whereas addition of excess Cd led to an impairment of broilers’ performance. Mortality of broilers did not differ between the four dietary treatments at any interval point or the whole period. The examined haematological parameters such as haematocrit, total blood protein concentration, and leukocytes types ranged within physiological values, revealing no negative health effects after simultaneous Cd and Se addition. The present study indicated that Se can help against the negative effects of Cd, but cannot counteract all of its negative effects.

Producing organic fish diets requires that the use of both fishmeal and fish oil (FO) be minimized and replaced by sustainable, organic sources. The purpose of the present study was to replace FO with organic oils and evaluate the effects on feed intake, feed conversion ratio (FCR), daily specific growth rate (SGR) and nutrient digestibility in diets in which fishmeal protein was partly substituted by organic plant protein concentrates. It is prohibited to add antioxidants to organic oils, and therefore the effects of force-oxidizing the oils (including FO) on feed intake and nutrient digestibility was furthermore examined. Four organic oils with either a relatively high or low content of polyunsaturated fatty acids were considered: linseed oil, rapeseed oil, sunflower oil and grapeseed oil. Substituting FO with organic oils did not affect feed intake (P > 0.05), FCR or SGR (P > 0.05) despite very different dietary fatty acid profiles. All organic plant oils had a positive effect on apparent lipid digestibility compared with the FO diet (P < 0.05), whereas there were no effects on the apparent digestibility of other macronutrients when compared with the FO diet (P > 0.05). Organic vegetable oils did not undergo auto-oxidation as opposed to the FO, and the FO diet consequently had a significantly negative effect on the apparent lipid digestibility. Feed intake was not affected by oxidation of any oils. In conclusion, the study demonstrated that it is possible to fully substitute FO with plant-based organic oils without negatively affecting nutrient digestibility and growth performance. Furthermore, plant-based organic oils are less likely to oxidize than FOs, prolonging the shelf life of such organic diets.

The influence of feeds containing varying dietary cation–anion differences (DCADs) with and without supplements of 25-hydroxyvitamin D (25(OH)D) on urine pH and excretion of macro minerals was determined in fistulated crossbred steers (mean live weight 315 ± 45 kg). A basal forage diet comprising lucerne hay and wheat chaff was used, to which varying quantities of MgCl2 or K2CO3 were added to achieve four levels of DCAD: −300, 50, 150 or 250 mEq/kg dry matter (DM). Steers were allocated to one of six treatments, one treatment for each diet and a further treatment for both the 50 and 150 mEq/kg DCAD diets, which were supplemented with 25(OH)D at a rate of 3 mg/steer per day. Urine pH from steers offered the diets comprising DCADs of 50, 150 and 250 mEq/kg ranging from 8.3 to 8.8. In treatments not containing 25(OH)D with DCADs of 50 to 250 mEq/kg, there were no significant differences in urine pH or Ca excretion. However, steers offered the diet with a DCAD of −300 mEq/kg DM produced urine with a significantly lower pH (6.5 to 7.5). Daily output of Ca in urine was also significantly higher from steers given this diet. Supplementation with 25(OH)D significantly increased urinary Ca excretion from steers offered diets of DCADs 50 and 150 mEq/kg DM. Estimates of daily urinary Ca excretion, calculated using the ratio of creatinine to Ca in ‘spot’ urine samples, were less variable than those based on total collection (residual mean square of 0.54 and 0.63, respectively).

The objective of this experiment was to investigate the effect of four perennial ryegrass cultivars: Bealey, Astonenergy, Spelga and AberMagic on the milk yield and milk composition of grazing dairy cows. Two 4 × 4 latin square experiments were completed, one during the reproductive and the other during the vegetative growth phase of the cultivars. Thirty-two Holstein–Friesian dairy cows were divided into four groups, with each group assigned 17 days on each cultivar during both experiments. Within each observation period, milk yield and milk composition, sward morphology and pasture chemical composition were measured. During the reproductive growth phase, organic matter digestibility (OMD) was greater for Bealey and Astonenergy (P < 0.001; +1.6%). AberMagic contained a higher stem proportion (P < 0.01; +0.06) and a longer sheath height (P < 0.001; +1.9 cm). Consequently, cows grazing AberMagic recorded a lower milk yield (P < 0.001; −1.5 kg/day) and a lower milk solids yield (P < 0.001; −0.13 kg/day). During the vegetative growth phase, OMD was greater (P < 0.001; +1.1%) for Bealey, whereas the differences between the cultivars in terms of sward structure were smaller and did not appear to influence animal performance. As a result, cows grazing Bealey recorded a higher milk yield (P < 0.001; +0.9 kg/day) and a higher milk solids yield (P < 0.01; +0.08 kg/day). It was concluded that grass cultivar did influence milk yield due to variations in sward structure and chemical composition.

Fatty acid translocase (FAT/CD36) is a membrane receptor that facilitates long-chain fatty acid uptake. To investigate its role in the regulation of long-chain fatty acid composition in muscle tissue, we studied and compared FAT/CD36 gene expression in muscle tissues of commercial broiler chickens and Chinese local Silky fowls. The results from gas chromatography–mass spectrometry analysis of muscle samples demonstrated that Chinese local Silky fowls had significantly higher (P < 0.05) proportions of linoleic acid (LA) and palmitic acid, lower proportions (P < 0.05) of arachidonic acid (AA) and oleic acid than the commercial broiler chickens. The mRNA expression levels of fatty acid (FA) transporters (FA transport protein-1, membrane FA-binding protein, FAT/CD36 and caveolin-1) in the m. ipsilateral pectoralis and biceps femoris were analyzed by Q-PCR, and FAT/CD36 expression levels showed significant differences between these types of chickens (P < 0.01). Interestingly, the levels of FAT/CD36 expression are positively correlated with LA content (r = 0.567, P < 0.01) but negatively correlated with palmitic acid content (r = −0.568, P < 0.01). Further experiments in the stably transfected Chinese hamster oocytes cells with chicken FAT/CD36 cDNA demonstrated that overexpression of FAT/CD36 improves total FA uptake with a significant increase in the proportion of LA and AA, and a decreased proportion of palmitic acid. These results suggest that chicken FAT/CD36 may selectively transport LA and AA, which may lead to the higher LA deposition in muscle tissue.

There are indications that intrauterine crowding may cause intrauterine growth retardation with the possibility of an impaired myofiber hyperplasia. The aim of the study was to confirm this by generating large differences in uterine space using sows that were unilaterally hysterectomized-ovariectomized (HO; crowded) or unilaterally oviduct ligated (OL; non-crowded). In the study, seven HO and seven OL Swiss Large White third parity sows were used. At farrowing, litter size and litter birth weight were determined. Subsequently, within each litter two male and two female progenies each with the respectively lowest (L) and highest (H) birth weight were sacrificed. Internal organs and brain were weighed, and longissimus (LM) and semitendinosus muscle (SM) samples were collected. Histological analyses were performed in both muscles using mATPase staining after preincubation at pH 4.3 and 10.2. Myosin heavy chain (MyHC) polymorphism was determined in the LM by means of SDS-PAGE. The number of piglets born alive was similar in both sow groups, but litter size expressed per uterine horn was lower (P < 0.05) in OL than HO sows. Consequently, OL progeny were markedly heavier (P < 0.01). Regardless of gender, the organs, the brain and the SM were heavier (P < 0.001) in OL and H compared with HO and L offspring, respectively. Compared with HO pigs, the SM of OL offspring tended (P < 0.1) to have more myofibers, which were of larger (P < 0.05) size. However, myofiber density appeared to be lower (P < 0.1) in the SM of OL than HO pigs. The impact of birth weight on myofiber characteristics was limited to the lower (P < 0.05) myofiber density in the SM and the larger (P < 0.01) myofiber size in the light portion of the SM of H than L offspring, whereas myofiber hyperplasia did not differ between birth weight categories. The SM, but not the LM, of male offspring had a greater (P < 0.05) myofiber density. This did not affect total SM myofiber number. The relative abundance of fetal and type I MyHC in the LM was lower (P < 0.05) and that of type II MyHC was greater (P < 0.001) in OL than HO pigs. The current data suggest that regardless of birth weight and gender, in the LM and SM of individuals born from a crowded environment, not only hyperplasia but also hypertrophy of myofibers is impaired and their maturity seems delayed.

The effect of feed restriction on gene expression of regulatory enzymes of intermediary metabolism was studied in two sheep breeds (Australian Merino and Dorper) subjected to two nutritional treatments: feed restriction (85% of daily maintenance requirements) and control (ad libitum feeding), during 42 days. The experimental animals (ram lambs) were divided into four groups, n = 5 (Australian Merino control (MC), Australian Merino Restriction (MR), Dorper control (DC) and Dorper Restriction (DR)). After the trial, animals were sacrificed and samples were taken from liver tissue to quantify glucose levels and gene expression of relevant intermediary metabolism enzymes (phosphofructokinase (PFK), pyruvate kinase (PK), phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase, glucose-6-phosphatase, glycogen synthase (GS), fatty acid synthase (FAS), glutamate dehydrogenase (GDH) and carbamoyl phosphate synthase (CPS)) through real-time PCR. During the experimental period, the MR animals lost 12.6% in BW compared with 5.3% lost by the Dorper lambs. MC and DC rams gained, respectively, 8.8% and 14% during the same period. Within the Dorper breed, restricted feed animals revealed a significant decrease over controls in the transcription of PFK (1.95-fold) and PK (2.26-fold), both glycolytic enzymes. The gluconeogenesis showed no change in the feed restricted animals of both breeds. DR feed group presented a significant decrease over the homologous Merino sheep group on GS. In both experimental breeds, FAS mRNA expression was decreased in restricted feed groups. GDH expression was decreased only in the DR animals (1.84-fold) indicating a reduced catabolism of amino acids in these animals. Finally, CPS was significantly (P < 0.05) higher in the Dorper sheep, indicating a facilitated urea synthesis in this breed. These results indicate a better adaptation of metabolic intermediate regulatory enzymes and hepatic glucose production of Dorper sheep to feed restriction concurring with the BW results in the experimental groups.

A buffalo oocyte-specific subtracted cDNA library was constructed to identify exclusively or preferentially oocyte-expressed genes. The library represented an enriched population of transcripts obtained from oocytes of diverse ovarian follicular origin and at different stages of in vitro maturation. A total of 1173 high-quality sequences of oocyte-specific genes were clustered into 645 unique sequences, out of which 65.76% were represented as singlets and 34.26% as contig expressed sequence tags (ESTs; clusters). Analysis of sequences revealed that 498 of these sequences were identified as a known sequence in mammalian species including buffalo, 103 as uncharacterized ESTs and 44 unknown sequences including 1 novel EST, so far not reported in any species. Gene ontology annotation classified these sequences into functional categories of cellular events and biological processes associated with oocyte competence. Expression status of the isolated unknown ESTs confirmed that many of these are expressed in oocytes exclusively and in others preferentially, some in excess of 80-fold greater in comparison with a variety of somatic tissues. The isolated novel EST was detected to be expressed exclusively in oocytes and testicular cells only. To our knowledge, this is the first report giving a detailed transcriptome account of oocyte-expressed genes in buffalo. This study will provide important information on the physiological control of oocyte development, as well as many questions yet to be addressed on the reproductive process of buffalo.

When embryos are cultured individually or in small groups, blastocyst yield efficiency and quality are usually reduced. The aim of this work was to investigate the effect of supplementation of the embryo culture medium (CM) with several growth factors (GFs) on embryo development and apoptosis rate when a reduced number of embryos were in vitro cultured. Two experimental studies (ES) were carried out. In ES 1, five treatments were tested to study the effect of GF on embryo development: Control (∼30 to 50 embryos cultured in 500 μl of CM); Control 5 (Five embryos cultured in 50 μl microdrops of CM), without addition of GF in either of the two control groups; epidermal GF (EGF); IGF-I; and transforming GF-α (TGF-α) (Five embryos were cultured in 50 μl microdrops of CM with 10 ng/ml EGF, 10 ng/ml IGF-I or 10 ng/ml TGF-α, respectively). In ES 2, following the results obtained in ES 1, four different treatments were tested to study their effect on embryo development and quality (number of cells per blastocyst and apoptotic rate): Control; Control 5; EGF, all three similar to ES 1; EGF + IGF-I group (five embryos cultured in 50 μl microdrops of CM with 10 ng/ml EGF and 10 ng/ml IGF-I). In both ESs, it was observed that a higher proportion of embryos cultured in larger groups achieved blastocyst stage than embryos cultured in reduced groups (22.6% v. 14.0%, 12.6% and 5.3% for Control v. Control 5, IGF-I, TGF-α groups in ES 1, and 24.9% v. 17.1% and 19.0% for Control v. Control 5 and EGF in ES 2, respectively; P < 0.05), with the exception of embryos cultured in medium supplemented with EGF (18.5%) or with EGF + IGF-I (23.5%), in ES 1 and ES 2, respectively. With regard to blastocyst quality, embryos cultured in reduced groups and supplemented with EGF, alone or combined with IGF-I, presented lower apoptosis rates than embryos cultured in reduced groups without GF supplementation (11.6% and 10.5% v. 21.9% for EGF, EGF + IGF-I and Control 5 groups, respectively; P < 0.05). The experimental group did not affect the total number of cells per blastocyst. In conclusion, this study showed that supplementation of the CM with EGF and IGF could partially avoid the deleterious effect of in vitro culture of small groups of bovine embryos, increasing blastocyst rates and decreasing apoptosis rates of these blastocysts.

Although rabbit does are generally single housed on rabbit farms worldwide, it has been suggested by some specialists and recommendation of organic rabbit production systems that group housing of does is more comfortable and similar to the living conditions of the European wild rabbits. The aim of this experiment was to compare production of single-caged (S) and group-housed does (G). The S does were housed in commercial rabbit cages (floor area 0.32 m2 and 0.3 m high). In treatment G, four does and one buck were housed in four pens measuring 7.7 m2 (half of the floor was deep litter and the other half was plastic slat), with four nest boxes in each pen (n = 16). In treatment S, approximately half of the does (n = 18) were inseminated 2 days after kindling (S-33), whereas in the remaining does (n = 16) AI was done 11 days after kindling (S-42). A single-batch system (all of the does in the group were inseminated on the same day) was used in both S treatments. Kindling rates were 77.6%, 85.2% and 45.6% in treatments S-33, S-42 and G, respectively (P < 0.05). During the experiment, the percentage of does that kindled 0, 1, 2, 3, 4 and 5 times were 17%, 25%, 17%, 25%, 17% and 0% (G); 0%, 0%, 0%, 8%, 69% and 23% (S-33); and 0%, 0%, 17%, 58% and 25% (S-42, in this treatment does had a maximum of four kindlings). There were no significant differences among treatments for litter size. In treatments S-33, S-42 and G, suckling mortality was 14.0%, 15.2% and 38.5%, respectively (P < 0.001); survival of does was 71%, 81% and 50% (P = 0.084); and faecal corticosterone concentrations were 61, 54 and 175 nmol/g (P < 0.001). The high mortality of kits was associated with stress and aggressive behaviour of does, including scratching, biting or killing the kits, which resulted in the high rates of mortality and culling, as well as shorter lifespan of does. Because of high stress, increased mortality and morbidity, and low productivity, group housing of rabbit does resulted in poorer animal welfare and increased production costs, and therefore is not recommended.

Black vultures (Coragyps atratus) are often present near calving sites, and under this situation they may play a positive role by removing animal carcasses and afterbirth or a negative role by attacking neonate calves or disturbing cow–calf behaviours following parturition. Cow–calf behaviour was recorded over a 4-year study period from a total of 300 births involving 200 Nellore, 54 Guzerat, 20 Gyr and 26 Caracu cows. The calving site in relation to the location of the herd, considering cow–calf pairs within, close or distant to the herd, the presence of vultures and the behaviour of cows and calves were recorded instantaneously, at 5-min interval. On average, vultures were present at 80% of the calving sites. The frequency of vultures present at calving sites was dependent on the years for the Nellore herd, increasing from 1998 to 2003. When vultures were present, the time that the cow was in contact with its calf decreased, and the percentage of time that the cow was standing still increased. Vultures were observed pecking cows and their neonates during 34.1% of all recordings. However, in only two cases pecking injuries were actually observed on calves that were noted to be very weak. The preliminary results suggest that although black vultures cannot be characterized as a predator of neonate calves, they sometimes attack neonate calves and their presence near the calving sites alter the behaviours of cows and calves.

Numerous studies have investigated the emotional effects of various acute, potentially alarming events in animals, but little is known about how an accumulation of emotional experiences affects fearfulness. Fearfulness is a temperament trait that characterizes the propensity of an individual to be frightened by a variety of alarming events. The aim of this study was to investigate a putative alteration of fearfulness in sheep repeatedly exposed to various aversive events. Forty-eight 5-month-old female lambs were used. Over a period of 6 weeks, 24 of them (treated group) were exposed daily to various unpredictable and uncontrollable aversive events related to predatory cues, social context and negative handling that can occur under farming conditions. The other 24 lambs (control group) were housed in standard farming conditions (predictable food distribution and group handling). Fearfulness (behavioural and physiological responses) was assessed before and after the treatment period by subjecting the lambs to three standardized tests: individual exposure to suddenness and then to novelty in a test arena, and group exposure to a motionless human in the home pen. As biomarkers of stress, leukocyte counts, heart rate and cortisol concentrations were measured in the lambs in their home pens. Before the treatment, the emotional responses of the groups did not differ. After the treatment, treated lambs approached the human less often, had less contact with the novel object and vocalized more than controls in individual tests, suggesting that long-term exposure to unpredictable and uncontrollable aversive events increases subsequent fearfulness in sheep. In addition, treated lambs had lower leukocyte counts, heart rate and cortisol levels, pointing to a chronic stress state. These findings suggest that increased fearfulness may be used as a sign of chronic stress in farm animals.

In Chile, cow carcasses present the highest bruise prevalence compared with other cattle categories; however, the causes of the bruises are frequently unknown. In this study, 52 cull cows were transported to the slaughterhouse in three batches under identical transport conditions. A combination of direct observation and video analyses was used to determine moment, pre-slaughter stage and cause of potential bruising events during the period from loading on the farm until stunning at the slaughterhouse. After slaughter, number of bruises, location on the carcass and characteristics of the bruises were assessed. Seventy-eight bruises were observed on 37 carcasses. Fifty-two bruises were linked back to their causal event. Results showed that 46% of these bruises were a result of interactions between animal and facility, and most of them were inflicted in the stunning box, 27% of the bruises originated from animal–animal interactions and were mostly inflicted during lairage, another 27% was a result of human–animal interactions and were mostly inflicted during loading and unloading of animals. The percentages of potential bruising events resulting in a bruise were 43%, 9% and less than 1% for animal–facility, human–animal and animal–animal interactions, respectively. Most bruises on the back site were inflicted when the animal was in the stunning box (91.2%), whereas bruises on the pin site were mostly (75%) inflicted during loading at the farm. One may conclude that in relative short journeys (⩽4 h) directly from farm to the slaughterhouse and long lairage times (>12 h), most bruises are the result of circumstances at the slaughterhouse. A substantial amount of these bruises could be avoided by proper animal handling and adequate stunning facilities.

The aim of this study was to assess unconsciousness in pigs during and after the exposure to gas mixtures of 70% nitrogen (N2) and 30% carbon dioxide (CO2) (70N30C), 80% N2 and 20% CO2 (80N20C) and 85% N2 and 15% CO2 (85N15C) compared with 90% CO2 in air (90C) by means of the Index of Consciousness®(IoC), their behaviour and the absence of brain stem reflexes. The experiment included three trials of 24 pigs divided into four groups according to the number of treatments. Half of the group was exposed for a short time and the other half for a long time (3 and 5 min for the N2/CO2 mixtures exposure and 2 and 3 min in 90C exposure, respectively). During exposure, the IoC and the electroencephalography suppression rate (ESR) were assessed, as well as the time to onset and percentage of gasping, loss of balance, vocalizations, muscular excitation and gagging. At the end of the exposure, the corneal reflex, rhythmic breathing and sensitivity to pain were each assessed at 10 s intervals for 5 min. Brain activity decreased significantly (P < 0.05) 37.60 s after the start of the exposure to 90% CO2, which was significantly earlier than in 70N30C, 80N20C and 85N15C exposure, (45.18 s, 46.92 s and 43.27 s, respectively). Before brain activity decreased, all pigs experienced gasping and loss of balance and a 98% muscular excitation. The duration of the muscular excitation was longer in animals exposed to 70N30C, 80N20C and 85N15C than 90C (P < 0.01). After a long exposure time, all animals exposed to 90C died, whereas the 30.4% of animals exposed to N2/CO2 gas mixtures survived. Pigs exposed to 85N15C recovered corneal reflex and sensitivity to pain significantly earlier than when exposed to 90C. Exposure to 90C causes a higher aversive reaction but a quicker loss of consciousness than N2/CO2 gas mixtures. Exposure to N2/CO2 gas mixtures causes a lower percentage of deaths and an earlier recovery of the brain stem activity than 90C, whereas the time to recover the cortical activity is similar. In conclusion, the inhalation of N2/CO2 gas mixtures reduces the aversion compared with high concentrations of CO2; however, the period of exposure for inducing unconsciousness may be longer in N2/CO2 gas mixtures, and the signs of recovery appear earlier, compared to CO2.

The aim of this study was to evaluate nitric oxide (NOx) concentration in infected and non-infected mammary quarters of dairy heifers before and after calving. The relationship between bacterial species and NOx concentrations, as well as correlation between NOx concentrations and postpartum somatic cell count (SCC), was assessed. Coagulase-negative staphylococci, Staphylococcus aureus and Escherichia coli were the bacteria commonly isolated during the pre- and postpartum period. Infected quarters had greater NOx concentrations than non-infected quarters before (30.81 v. 22.83 μM/ml, P < 0.05) and after (9.56 v. 5.77 μM/ml, P < 0.0001) calving. It was determined that the interaction between sampling period and infectious status had no effect on NOx concentration (P < 0.16). Infected quarters had greater SCC (log10) than healthy quarters (4.95 v. 4.39; P < 0.0001). NOx concentrations, however, did not correlate with SCC (r = 0.02). In summary, changes in NOx concentration were mainly dependent on the infectious status of the quarters with variations among the bacterial species (P < 0.05).

The addition of some fat co- and by-products to feeds is usual nowadays; however, the regulations of their use are not always clear and vary between countries. For instance, the use of recycled cooking oils is not allowed in the European Union, but they are used in other countries. However, oils recovered from industrial frying processes could show satisfactory quality for this purpose. Here we studied the effects of including oils recovered from the frying industry in rabbit and chicken feeds (at 30 and 60 g/kg, respectively) on the fatty acid (FA) and tocol (tocopherol + tocotrienol) compositon of meat, liver and plasma, and on their oxidative stability. Three dietary treatments (replicated eight times) were compared: fresh non-used oil (LOX); oil discarded from the frying industry, having a high content of secondary oxidation compounds (HOX); and an intermediate level (MOX) obtained by mixing 50 : 50 of LOX and HOX. The FA composition of oil diets and tissues was assessed by GC, their tocol content by HPLC, the thiobarbituric acid value was used to assess tissue oxidation status, and the ferrous oxidation-xylenol orange method was used to assess the susceptibility of tissues to oxidation. Our results indicate that FA composition of rabbit and chicken meat, liver and plasma was scarcely altered by the addition of recovered frying oils to feed. Differences were encountered in the FA composition between species, which might be attributed mainly to differences in the FA digestion, absorption and metabolism between species, and to some physiological dietary factors (i.e. coprophagy in rabbits that involves fermentation with FA structure modification). The α-tocopherol (αT) content of tissues was reduced in response to the lower αT content in the recovered frying oil. Differences in the content of other tocols were encountered between chickens and rabbits, which might be attributable to the different tocol composition of their feeds, as well as to species differences in the digestion and metabolism of tocols. Tissue oxidation and susceptibility to oxidation were in general low and were not greatly affected by the degree of oxidation of the oil added to the feeds. The relative content of polyunsaturated fatty acids/αT in these types of samples would explain the differences observed between species in the susceptibility of each tissue to oxidation. According to our results, oils recovered from the frying industry could be useful for feed uses.

Rabbits are very sensitive to heat stress because they have difficulty eliminating excess body heat. The objective of the current study was to evaluate the effects of heat stress on slaughter weight, dressing percentage and carcass and meat quality traits of rabbits from two genetic groups. Ninety-six weaned rabbits were used: half were from the Botucatu genetic group and half were crossbreds between New Zealand White sires and Botucatu does. They were assigned to a completely randomized design in a 2 × 3 factorial arrangement (two genetic groups and three ambient temperatures: 18°C, 25°C and 30°C) and kept under controlled conditions in three environmental chambers from 5 to 10 weeks of age. Slaughter took place at 10 weeks, on 2 consecutive days. Meat quality measurements were made in the longissimus muscle. Actual average ambient temperature and relative humidity in the three chambers were 18.4°C and 63.9%, 24.4°C and 80.2% and 29.6°C and 75.9%, respectively. Purebred rabbits were heavier at slaughter and had heavier commercial and reference carcasses than crossbreds at 30°C; however, no differences between genetic groups for these traits were found at lower temperatures. No genetic group × ambient temperature interaction was detected for any other carcass or meat quality traits. The percentages of distal parts of legs, skin and carcass forepart were higher in crossbred rabbits, indicating a lower degree of maturity at slaughter in this group. The percentage of thoracic viscera was higher in the purebreds. Lightness of the longissimus muscle was higher in the purebreds, whereas redness was higher in the crossbreds. Slaughter, commercial and reference carcass weights and the percentages of thoracic viscera, liver and kidneys were negatively related with ambient temperature. Commercial and reference carcass yields, and the percentage of distal parts of legs, on the other hand, had a positive linear relationship with ambient temperature. Meat redness and yellowness diminished as ambient temperature increased, whereas cooking loss was linearly elevated with ambient temperature. Meat color traits revealed paler meat in the purebreds, but no differences in instrumental texture properties and water-holding capacity between genetic groups. Purebred rabbits were less susceptible to heat stress than the crossbreds. Heat stress resulted in lower slaughter and carcass weights and proportional reductions of organ weights, which contributed to a higher carcass yield. Moreover, it exerted a small, but negative, effect on meat quality traits.

An experiment was set up for (i) comparing Australian and French consumer preferences to beef and to (ii) quantify how well the Meat Standards Australia (MSA) grading model could predict the eating quality of beef in France. Six muscles from 18 Australian and 18 French cattle were tested as paired samples. In France, steaks were grilled ‘medium’ or ‘rare’, whereas in Australia ‘medium’ cooking was used. In total, 360 French consumers took part in the ‘medium’ cooking test, with each eating half Australian beef and half French beef and 180 French consumers tested the ‘rare’ beef. Consumers scored steaks for tenderness (tn), juiciness (ju), flavour liking (fl) and overall liking (ov). They also assigned a quality rating to each sample: ‘unsatisfactory’, ‘satisfactory everyday quality’ (3*), ‘better than everyday quality’ (4*) or ‘premium quality’ (5*). The prediction of the final ratings (3*, 4*, 5*) by the French consumers using the MSA-weighted eating quality score (0.3 tn + 0.1 ju + 0.3 fl + 0.3 ov) was over 70%, which is at least similar to the Australian experience. The boundaries between ‘unsatisfactory’, 3*, 4* and 5* were found to be ca. 38, 61 and 80, respectively. The differences between extreme classes are therefore slightly more important in France than in Australia. On average, even though it does not have predictive equations for bull meat, the mean predicted scores calculated by the MSA model deviated from observed values by a maximum of 5 points on a 0 to 100 scale except for the Australian oyster blade and the French topside, rump and outside (deviating by <15). Overall, the data indicate that it would be possible to manage a grading system in France as there is high agreement and consistency across consumers. The ‘rare’ and ‘medium’ results are also very similar, indicating that a common set of weightings and cut-offs can be employed.