Do domestic hens discriminate between familiar and unfamiliar conspecifics in the absence of visual cues?

Posted in: Welfare by admin on January 1, 2004 | No Comments

If allowed to rely on visual, auditory, and olfactory cues from live stimulus birds, domestic fowl are able to discriminate between familiar and unfamiliar conspecifics. However, some wild fowl are forced to rely on non-visual cues to recognize their group mates. In the current study, domestic chickens were tested to see if they could discriminate between familiar and unfamiliar conspecifics in the absence of visual cues. Two preference experiments were conducted. In each test, two live hens (one familiar and one unfamiliar) were presented to the test hen. In experiment one, the test hen was separated by the stimulus hen by only a wire-mesh, allowing the test hen to receive visual, auditory, and olfactory cues from the stimulus hens. In experiment two, visual contact was prevented by using an opaque black cloth as a separator rather than the wire-mesh. The aggregation time with the familiar and unfamiliar bird was recorded as a measure of preference. In experiment one, hens showed significant discrimination between familiar and unfamiliar conspecifics, although their preference for the familiar or unfamiliar bird depended on the experimental series in which they were housed. Hens in experiment two, which had to rely on non-visual cues, did not appear able to discriminate between familiar and unfamiliar hens.

The effect of repeated application of electrical stunning on the welfare of pigs.

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At present approximately 13 million pigs are slaughtered annually in the United Kingdom. Although legislation requires the production of immediate insensibility, implying that a stun can be applied only once, the practice of repeat application of electrical stunning is common. It is not clear whether a repeat application is as effective as the initial stun and if there are any potential welfare problems associated with the practice. This study investigated the effects of repeat applications of electrical stunning (200 V, 50 Hz) following different delays of 15, 60 or 180 s between the initial stun and the repeat applications. Following stunning, the durations of spontaneous physical activity, time to return of reflexes and the duration of the epileptiform activity in the electrocorticogram were examined. The results showed that repeat application of electrical stunning can produce successive epileptic activity and therefore an effective stun. The duration of tonic and clonic phase activity following repeat application was significantly shorter than after a single stun only. There was a tendency for the reflexes to return more quickly following repeat application. The use of electrical stunning to re-stun pigs appears to raise no welfare concerns and although commonly used, should be applied out of necessity rather than as routine practice.

Assessment of mental stress in warmblood horses: heart rate variability in comparison to heart rate and selected behavioural parameters

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Heart rate variability was investigated in order to determine whether it could, in turn, assess alterations of the autonomic nervous system at different levels of excitement. Warmblood horses were given a challenging ground exercise task during which their behavioural and physiological responses could be studied. Prior to commencement of the study, the horses were evaluated at rest and during forward walking, then while made to walk backwards continuously for three minutes, according to a standardised protocol. The horses were then exposed to two training sessions, followed by a re-evaluation of backward walking. Heart rate and heart rate variability parameters, such as the standard deviation of the beat-to-beat intervals, the low (sympathetic tone) and high (parasympathetic tone) frequency component of heart rate variability, and their ratio (index representing the sypatho-vagal balance), were sampled at rest, during forward walking, during the first backward walk, and during the second backward walk. Using video recordings taken during both backward walking sessions, stress-related behaviour was determined. The first backward walk experiment induced a rise in heart rate, low frequency heart rate variability, and the low frequency/high frequency heart rate variability ratio, compared to rest and forward walking. A decrease of high frequency heart rate variability in response to the first backward walking session was noted in comparison to rest and forward walking. The standard deviation of the beat-to-beat intervals decreased from both forward walking and rest, but only the standard deviation of the beat-to-beat intervals at rest was significant. In the second backward walking session, heart rate and the parameters of the sympathetic branch of the autonomic nervous system (low frequency component of heart rate variability, and the index representing the sypatho-vagal balance) were decreased and the vagal tone (high frequency component of heart rate variability) was increased compared to the first backward walking session. According to the duration of stress-indicating behavioural patterns, a decrease of excitement after the two training sessions occurred. At that time backward walking did not differ from forward walking for any parameter measured. It was found that there were correlations between heart rate variability parameters and stress-indicating behaviour, as well as heart rate. The results of this study indicated that the heart rate variability parameters (i.e. both the low frequency and high frequency components) were valuable measures for quantifying sympatho-vagal balance. These measures allow for a more precise assessment of the responses of heart rate and standard deviation of beat-to-beat intervals to mental stress during low intensity exercise.

Assessment of the aversion of hens to different gas atmospheres using an approach-avoidance test.

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High concentrations of CO2 have been used for stunning poultry, but have been considered inhumane because the birds appear to find it aversive. However, Ar or a mixture of Ar and CO2 have been suggested to be more humane. The responses of hens to different gas atmospheres were tested during a series of approach-avoidance tests. Twelve hens were trained in the test apparatus, which consisted of a upper and lower chamber, which were connected by a chute. During the actual testing phase, gas would be injected into the lower chamber. The hens did not have access to feed the night before the training session. During the actual training session, hens were placed in the upper chamber and feed was placed in the lower chamber. The feed was used to motivate the hens to enter the lower chamber. Once the birds were trained to enter the lower chamber, the tests began. During each of six test sessions, a different gas treatment was injected into the lower chamber: air, 30% CO2 -in-air, 45% CO2 -in-air, 60% CO2 -in-air, 70% Ar / 30% CO2, and Ar. All hens were randomly exposed to each treatment. Training continued throughout the experiment, and alternated with the testing days. The results indicated that birds took longer to leave the upper chamber during the training session the day after they have been exposed to 45% CO2 -in-air and Ar. However, there were no differences among the treatments in the latency to leave the upper chamber. There were no differences in the number of stops and retreats when the hens were approaching the lower chamber that was enriched with CO2. The lowest number of stops and retreats were found in the control and Ar treatments. Only one hen was not stunned by the CO2-enriched and Ar-enriched atmospheres. There were no differences in the percentages of hens stunned among the stunning gas treatments. Hens in the 30% CO2 -in-air treatment entered the lower chamber at close to the same frequency as in the Ar treatment. When exposed to 60% CO2 -in-air, most of the hens became stunned in the chute on the way to the lower chamber. Hens that entered the lower chamber before being stunned were intermediate for 45% CO2 -in-air and 70% Ar / 30% CO2. The authors concluded that when stunning/killing chickens, there does not seem to be a welfare problem when using mixtures of up to 60% CO2 -in-air compared to 70% Ar / 30% CO2. Using Ar appears to be slightly more welfare-friendly, but not enough to warrant its use over the other options.

Needle-Free Immunization as Effective as Needle and Syringe Method

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Vaccination of livestock is crucial to developing specific immune resistance to diseases that otherwise cost producers billions of dollars. Vaccination of livestock with needles, intramuscular and subcutaneous, can incur costs through animal stress, vaccine residues, injection site lesions and broken needles. Needle-free injection offers several benefits over traditional means. Vaccine is dispersed as minute particles in skin and other tissue, greatly increasing exposure to white blood cells, and thus improving vaccine uptake. Entry points are minute, minimizing tissue damage at the injection site. The injector can be loaded for multiple injections and needle stick injuries are eliminated. This study, carried out at the University of Saskatchewan.s Vaccine & Infectious Disease Organization (VIDO), evaluated commercial vaccine delivery to piglets using a low-pressure, needle-free jet injector against intra-muscular delivery and found that resulting immunity in needle-free animals was as good or better than that developed by animals immunized using a syringe and needle. Animals immunized with the needle-free jet injector also experienced milder clinical disease. This work confirmed similar results achieved by researchers using other drugs or vaccines. The amount of vaccine remaining on the skin surface post-vaccination with the needle-free method suggested that further studies of needle-free injections could lead to establishment of much smaller effective vaccination doses with this system.

Effect of supplemental tryptophan, vitamin E, and a herbal product on response by pigs to vibration.

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Transportation can result in increased stress for pigs, which has been related to economic losses. The effect of supplementing feed or water with tryptophan, vitamin E or a herbal product (Sedafit) on the behaviour and physiology or pigs during simulated transportation (vibration) was studied. Water supplemented with tryptophan caused pigs to lie down more during the second hour of vibration. Compared to the control group, both during and after the stress of simulated transport, an increase in vitamin E in the feed caused a decrease in the peak heart rate, ventricular ectopic beats and ST elevation. Similarly, water supplemented with Sedafit resulted in smaller increases in the measured heart variables compared to the control group (before and after the stressor). Tryptophan calmed the pigs, such that they spent more time lying. Vitamin E and Sedafit had sedative and antianxiety effects based on the decrease in relative changes of some heart rate variables during and after vibration.

Pork Production Trends: Forecasting Our Future

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From 1998 to 2003, world pork production grew by 11%, while Canada grew by 42%. The productivity of the sow herd in the US and Canada today is still steadily improving. This is due to several factors that include improved management, improved genetics, modern facilities, and artificial insemination. An increase in slaughter weight improves the cost of each pig produced, because the costs can be spread out over more poundage. Although the number of pigs produced in the US and Canada is increasing, the number of operations is decreasing. In the US there has been a steady increase in production contracts. Hog producers that use contracts tend to be happier with their business than those that raise their own. The current trend in dieting is low carbohydrate/high protein diet, and this is contributing to an increase in the amount of meat eaten per individual. The number of pigs being bred and farrowed is increasing steadily, and is predicted to increase into 2005 as well.

Tracking Pork from Pen to Plate

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In order to increase public awareness of food safety, a pork tracking system is being developed. The need for this traceability comes from increasing focus on food safety, need for zoning in the case of disease, tracking drug residues, recall in the event of contamination, feedback to allow quality control, protection against bioterrorism, and marketing the “Canada Brand” worldwide. This system will also help Canada internationally to gain a competitive advantage. It will help disease-free geographical regions to continue exporting if a major disease outbreak occurs. Tracing methods for live animals include ear tags and tattoos for being cheap and reliable. Dead pigs at the plant can be as simple as a paper bar code that can be read and reprinted at each point where a cut is divided into smaller portions. The ultimate objective will be to trace every piece of meat from plate to farm through each step of the value chain: retail, distribution, processing, slaughter, production, nutrition, breeding, and genetics. The implementation into slaughter plants is much more difficult and would cost potentially $15 million to implement, resulting in an extra $4.50 extra per carcass, which is simply unacceptable. DNA tracking can link meat back to the farm of origin and is cheap and easy to implement. It is very accurate and free of human error compared to the hand-labelling systems. Maple Leaf Foods plans to introduce traceability in 3 stages: DNA tracking to the farm with live animal tracking to the plant, tracking through slaughter plant, and public access through the internet. In December 2002 Maple Leaf Foods placed a contract with Pyxis Genomics Inc. to trace meat back to the mother of the slaughter pig. Today the cost of DNA typing a single mother is about $35, and about $1 per carcass from that sow. The largest cost is the initial start-up cost of DNA typing the sow herd. Within 3 years the cost is expected to drop to about $6 per mother and less than 10 cents per carcass. Costs of DNA traceability can be recovered by adding value to the end product or as a cost of increasing market share. DNA traceability can also improve genetics because of its ability to track either defective or excellent meat back to the sow.

Characterization of an X-chromosome PCR–RFLP marker associated with fat deposition and growth in the pig

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The X-chromosome, highly conserved within mammals, has been shown to contain major
quantitative trait loci (QTL) for growth and fat deposition in the pig. We have discovered a
BamHI polymerase chain reaction restriction fragment length polymorphism (PCR–RFLP)
marker that was assigned to the porcine X-chromosome by two-point and multi-point
linkage analysis following genotyping of a three-generation Berkshire by Yorkshire reference
family. The marker was positioned 9 cM telomeric to SW2126 and 15.6 cM centromeric
to SW1943. Sequence flanking the marker was found to have high similarity to
existing database porcine DNA repeat elements. Association analyses of the BamHI marker
for growth and meat quality traits in the reference family revealed significant association
with marbling (P < 0.03), 10th rib back fat (P < 0.09) and total lipid percentage (P < 0.05), as well as with loin eye area (P < 0.04), average glycolytic potential (P < 0.03) and average lactate content (P < 0.04). Further studies are required to determine the X-chromosome functional gene affecting fat deposition and growth in the pig.

Digestibility of dried and ensiled sweet potato roots and vines and their effect on the performance and economic efficiency of F1 crossbred fattening pigs

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