Pol Llonch

Assessment of unconsciousness in pigs during exposure to nitrogen and carbon dioxide mixtures

The aim of this study was to assess unconsciousness in pigs during and after the exposure to gas mixtures of 70% nitrogen (N(2)) and 30% carbon dioxide (CO(2)) (70N30C), 80% N(2) and 20% CO(2) (80N20C) and 85% N(2) and 15% CO(2) (85N15C) compared with 90% CO(2) 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 N(2)/CO(2) 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% CO(2), 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 N(2)/CO(2) 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 N(2)/CO(2) gas mixtures. Exposure to N(2)/CO(2) 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 N(2)/CO(2) gas mixtures reduces the aversion compared with high concentrations of CO(2); however, the period of exposure for inducing unconsciousness may be longer in N(2)/CO(2) gas mixtures, and the signs of recovery appear earlier, compared to CO(2).

Current available strategies to mitigate greenhouse gas emissions in livestock systems: an animal welfare perspective.

Livestock production is a major contributor to greenhouse gas (GHG) emissions, so will play a significant role in the mitigation effort. Recent literature highlights different strategies to mitigate GHG emissions in the livestock sector. Animal welfare is a criterion of sustainability and any strategy designed to reduce the carbon footprint of livestock production should consider animal welfare amongst other sustainability metrics. We discuss and tabulate the likely relationships and trade-offs between the GHG mitigation potential of mitigation strategies and their welfare consequences, focusing on ruminant species and on cattle in particular. The major livestock GHG mitigation strategies were classified according to their mitigation approach as reducing total emissions (inhibiting methane production in the rumen), or reducing emissions intensity (Ei; reducing CH4 per output unit without directly targeting methanogenesis). Strategies classified as antimethanogenic included chemical inhibitors, electron acceptors (i.e. nitrates), ionophores (i.e. Monensin) and dietary lipids. Increasing diet digestibility, intensive housing, improving health and welfare, increasing reproductive efficiency and breeding for higher productivity were categorized as strategies that reduce Ei. Strategies that increase productivity are very promising ways to reduce the livestock carbon footprint, though in intensive systems this is likely to be achieved at the cost of welfare. Other strategies can effectively reduce GHG emissions whilst simultaneously improving animal welfare (e.g. feed supplementation or improving health). These win-win strategies should be strongly supported as they address both environmental and ethical sustainability. In order to identify the most cost-effective measures for improving environmental sustainability of livestock production, the consequences of current and future strategies for animal welfare must be scrutinized and contrasted against their effectiveness in mitigating climate change.

Effect of the duration of road transport on the physiology and meat quality of lambs

To assess the effect of transport duration on animal welfare and meat quality of lambs, two trials were performed: Forty Ile-de-France × Merino lambs were used in Trial 1 and 40 Comisana lambs in Trial 2. In both trials, the lambs, aged between 14 and 16 weeks, were divided into two groups of 20 animals. One group was subjected to a 1-h period of transportation (T1) and the other to a 24-h period of transportation (T24), both in the same truck and arriving to the same slaughterhouse at the same time. The effect of transport on serum biochemistry variables (cortisol, aspartate transaminase, lactate dehydrogenase, blood urea nitrogen, creatine kinase, creatinine and total proteins), salivary cortisol, metabolites of cortisol in faeces, intra-ruminal temperature and meat quality (pH, conductivity, expressible juice, colour and shear force) was assessed. In both studies, the duration of transport did not affect serum and salivary cortisol concentration (P > 0.05). However, in Trial 2, lambs exposed to 24-h transport had a higher concentration of faecal cortisol metabolites than did those transported for 1 h (P 0.05), with the exception of blood urea nitrogen which was higher in Trial 1 for the T24 group (P 0.05). Nevertheless, in Trial 2, lambs exposed to 24-h transport had higher values of colour attribute of a* (red trend) and less tenderness or higher values of shear force (P < 0.05). The present study showed that although there is little effect on meat quality, signs of stress are detectable in lambs transported for 24 h. Therefore, in the case of lambs, the effect of long transportation periods must be considered more in terms of animal welfare than in terms of product quality.

Association of Temperament and Acute Stress Responsiveness with Productivity, Feed Efficiency, and Methane Emissions in Beef Cattle: An Observational Study

The aim of this study was to assess individual differences in temperament and stress response and quantify their impact on feed efficiency, performance, and methane (CH4) emissions in beef cattle. Eighty-four steers (castrated males) (Charolais or Luing) were used. Temperament was assessed using two standardized tests: restlessness when restrained [crush score (CS)] and flight speed (FS) on release from restraint. Over a 56-day period individual animal dry matter intake (DMI) and weekly body weight was measured. Ultrasound fat depth was measured at the end of 56 days. Average daily gain (ADG), feed conversion ratio (FCR), and residual feed intake (RFI) were calculated. After the 56-day test period, animals were transported in groups of six/week to respiration chamber facilities. Blood samples were taken before and 0, 3, 6, and 9 h after transport. Plasma cortisol, creatine kinase (CK), glucose, and free fatty acids (FFA) were determined to assess physiological stress response. Subsequently, CH4 emissions were measured over a 3-day period in individual respiration chambers. CS (1.7 ± 0.09) and FS (1.6 ± 0.60 m/s) were repeatable (0.63 and 0.51, respectively) and correlated (r = 0.36, P < 0.001). Plasma cortisol, CK, and FFA concentrations increased after transport (P = 0.038, P = 0.006, and P < 0.001, respectively). Temperament (CS) and CK concentration were correlated (r = 0.29; P = 0.015). The extreme group analysis reveals that excitable animals (FS; P = 0.032) and higher stress response (cortisol, P = 0.007; FFA, P = 0.007; and CK, P = 0.003) were associated with lower DMI. ADG was lower in more temperamental animals (CS, P = 0.097, and FS, P = 0.030). Fat depth was greater in steers showing calmer CS (P = 0.026) and lower plasma CK (P = 0.058). Temperament did not show any relationship with RFI or CH4 emissions. However, steers with higher cortisol showed improved feed efficiency (lower FCR and RFI) (P < 0.05) and greater CH4 emissions (P = 0.017). In conclusion, agitated temperament and higher stress responsiveness is detrimental to productivity. A greater stress response is associated with a reduction in feed intake that may both increase the efficiency of consumed feed and the ratio of CH4 emissions/unit of feed. Therefore, temperament and stress response should be considered when designing strategies to improve efficiency and mitigate CH4 emissions in beef cattle.

Effect of high temperatures on breeding rabbit behaviour

The present work is focussed on the behavioural response of rabbits (Oryctolagus cuniculus) housed in typical commercial conditions subjected to two different environmental temperature circadian cycles: one below the combination of temperature and humidity that is considered as stressful for rabbits, and the other with some hours a day subjected to moderately stressful temperatures. During the experiment, a total of 55 commercial breeding hybrid rabbits were housed in each room (43 nulliparous does and 12 bucks). Of these, 10 females (six 105 days old and four 80 days old) and 6 males (180 days old) were studied for 12 days, 12 h a day using video cameras to later scan sample for behaviour at 5-min intervals. Rabbits were divided into two rooms. Five females and three males were housed at 18.4°C mean temperature (Room A). The other five females and three males were housed at 20.1°C for 17 h a day, and at a temperature humidity index from 23.6 to 28.2 for the remaining 7 h (Room B). Posture (lying, sitting, prostrated or moving) and behaviour (grooming, exploring, resting, feeding and drinking) were assessed. Faecal cortisol metabolites (FCM) were also analysed, once before and after the behavioural study, from seven samples in each room. Statistical analyses were performed using the GENMOD procedure in SAS. No differences were found between rooms in FCM during the behaviour assessment. However, the presence of resting behaviour and prostration was higher (P < 0.05) in Room B than Room A and the opposite (P < 0.05) was observed for lying, sitting and exploring. In the case of grooming, a compensatory effect was observed in Room B, as rabbits reduced this activity in the warmest period of the day but increased it just before and after this period, which was not seen in Room A. It is concluded that behavioural changes can be observed in does and bucks subjected to moderately stressful thermal conditions before those changes can be seen in faecal cortisol concentration.