Biomedical subjects
I J Duncan
Publications and source records attributed to I J Duncan.
Rearing with males accelerates onset of sexual maturity in female domestic fowl.
Two experiments were conducted to investigate the effects of male presence on sexual maturation and sexual responses toward humans in laying strain females. In Experiment 1, two flocks of 50 medium-hybrid females were reared without males (separate-sex) and two flocks with males (mixed-sex) from 1 d of age. Mixed-sex females came into lay sooner and laid more eggs up to 22 wk of age than separate-sex females (P < 0.05). Comb size was also greater in mixed-sex females at 15 and 20 wk of age (P < 0.05). In Experiment 2, six replicate groups per treatment with n = 10 females per group were reared in separate-sex, mixed-sex, or adjacent to mixed-sex groups. Rearing adjacent to mixed-sex groups, which allowed visual and auditory contact with males, was just as effective for accelerating sexual maturation as was rearing in mixed-sex groups. Females reared in and adjacent to mixed-sex groups began to lay earlier (P < 0.05) and had larger combs (P < 0.05) than separate-sex females. However, after 22 wk of age, egg production rates of separate-sex females surpassed those of mixed-sex and adjacent females, resulting in similar numbers of eggs produced through 30 wk of age (P > 0.10). During tests for sexual responsiveness to humans, over 80% of females in separate-sex and adjacent to mixed-sex groups assumed a sexual crouch, whereas less than 20% of females in mixed-sex groups crouched (P < 0.001, chi-square). The degree of contact with males during rearing affected the females' physiological measures of reproductive function differently than behavioral measures.
Poultry welfare in North America: opportunities and challenges.
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Behavior and behavioral needs.
An understanding of behavior is important in any consideration of poultry welfare. Behavior is a good indicator of states of suffering such as fear, frustration, and pain. It might also be possible to use social interactions as indicators of welfare. The possibility of using "luxury" behavior, such as play and exploratory behavior, as an indicator of positive emotional states, requires investigation. Important welfare consequences arise from the fact that some behavior may be so strongly motivated as to constitute a "need". A behavioral need will arise in the case of behavior, such as nesting, that is controlled largely by internal factors, because these factors will be present no matter what type of environment is provided. Behavior triggered largely by external stimuli, such as responses to predators, will not give rise to a need if the external factors can be removed from the environment. Dustbathing is an example of behavior controlled by complex interactions between internal and external factors; the extent to which this constitutes a need is still being debated. If a behavioral need arises, then it is important that the environment provided allows it to be performed without damage to the performer or other birds. It should also be remembered that birds may need to perform behavior, including appetitive as well as consummatory elements, although the functional consequences of these are no longer required for survival. Finally, the performance of certain behavior leads to an increase in health or physical condition that improves welfare later in life.
Effects of resistance to milk flow and the provision of hay on nonnutritive sucking by dairy calves.
This study examined effects of resistance to milk flow and the provision of hay on the duration of nutritive sucking and subsequent nonnutritive sucking by dairy calves. In a series of four experiments, 12 male Holstein calves were individually fed milk from an artificial teat. Resistance to milk flow was varied by adjusting the orifice size within the milk supply tube. Using a Latin square design, each calf was fed the same quantity of milk using four orifice sizes (one per day for 4 consecutive d). The duration of nutritive sucking (time required to finish the milk meal) was longer when calves were fed from the smallest orifice size (0.16-cm diameter) than when calves were fed from the largest orifice size (0.55-cm diameter). Calves compensated for resistance to milk flow in an attempt to maintain milk intake; however, changes in sucking rate alone were probably not responsible for observed differences in the rate of milk consumption from different orifice sizes. The duration of nonnutritive sucking (sucking of the teat following the milk meal) was significantly reduced when calves were fed from the smallest orifice compared with that when calves were fed from the largest orifice. Nonnutritive sucking was reduced but not eliminated even with the longest meal duration. The provision of hay to calves following the meal also significantly reduced the amount of nonnutritive sucking. Reduction in flow rate when calves drink milk through a teat and the provision of hay after the meal can reduce the incidence of nonnutritive sucking following the meal and may help to limit cross-sucking in group housing systems.
Recognition of chitin and proteins in invertebrate cuticles using analytical pyrolysis/gas chromatography and pyrolysis/gas chromatography/mass spectrometry.
Flash pyrolysis/gas chromatography (py/GC) and py/GC/mass spectrometry (MS) have been utilized to characterize the cuticles of invertebrates chemically. Pyrolysis products have been identified and assigned to specific cuticular components. Acetylpyridones, acetamidofuran, 3-acetamido-5-methylfuran and 3-acetamido-(2 and 4)-pyrones are proposed as characteristic pyrolysis markers for chitin. Pyrolysis products displaying ions of m/z 70, 154, 168, 194 are thought to derive from diketopiperazine structures and provide potential markers for proteins and peptides in which proline, alanine, valine, arginine and glycine are the dominant amino acids. These products, constituting specific pyrolysis markers for invertebrate cuticles, may reflect the amino acid composition of their constituent structural proteins. The source of the various pyrolysis products of proteins has been verified by pyrolysis of reference proteins, peptides and amino acid mixtures. The presence of additional pyrolysis products related directly to histidine and catechol moieties is consistent with the chemical structure and composition proposed for arthropod cuticles based on recent work utilizing solid state 13C and 15N nuclear magnetic resonance. This study constitutes the first comprehensive chemical characterization of the pyrolysis products of invertebrate cuticles and provides the basis for future investigations requiring qualitative screening for cross-linked chitin and proteins in modern and fossil cuticles and in materials, e.g. geopolymers, that may be derived from them.
Practices of concern.
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Measuring preferences and the strength of preferences.
In this review, it is argued that welfare concerns what animals feel. Preference tests give a good first indication of how animals feel and are therefore extremely valuable in animal welfare studies. Methods of overcoming the shortcomings of preference tests are discussed. In order that the results from preference tests be interpreted properly, they should be followed up with appropriate tests to measure the strength of preference. Examples of research in this area that have focused on poultry are given.
Assessment of pain associated with degenerative hip disorders in adult male turkeys.
The extent to which degenerative hip disorders in adult male turkeys result in pain was investigated in a two-period crossover experiment. The birds in six pens received daily injections of an anti-inflammatory steroid (betamethasone) during week 1 and control injections of physiological saline in week 3. The turkeys in the other six pens received saline in week 1 and steroid in week 3. Behavioural observations of the birds during weeks 1 and 3 revealed that the steroid treatment resulted in more spontaneous activity. The steroid-treated birds also showed speedier movement in a sexual activity test in weeks 1 and 3. Post mortem examination revealed that all the turkeys were suffering from degenerative hip disorders. It is concluded that degenerative hip disorders in adult male turkeys result in a state of chronic pain which inhibits spontaneous activity and sexual activity.
The implications of cognitive processes for animal welfare.
In general, codes that have been designed to safeguard the welfare of animals emphasize the importance of providing an environment that will ensure good health and a normal physiological and physical state, that is, they emphasize the animals' physical needs. If mental needs are mentioned, they are always relegated to secondary importance. The argument is put forward here that animal welfare is dependent solely on the cognitive needs of the animals concerned. In general, if these cognitive needs are met, they will protect the animals' physical needs. It is contended that in the few cases in which they do not safeguard the physical needs, it does not matter from a welfare point of view. The human example is given of being ill. It is argued that welfare is only adversely affected when a person feels ill, knows that he or she is ill, or even thinks that he or she is ill, all of which processes are cognitive ones. The implications for welfare of animals possessing certain cognitive abilities are discussed. For example, the extent to which animals are aware of their internal state while performing behavior known to be indicative of so-called states of suffering, such as fear, frustration, and pain, will determine how much they are actually suffering. With careful experimentation it may be possible to determine how negative they feel these states to be. Similarly, the extent to which animals think about items or events absent from their immediate environment will determine how frustrated they are in the absence of the real item or event but in the presence of the cognitive representation.
Premature development of erosive osteoarthritis of hands in patients with chronic renal failure.
The prevalence of grade III or IV osteoarthritis was determined in 210 patients with chronic renal failure, of whom 94 were receiving chronic haemodialysis and 116 had functioning renal transplants. The prevalence of grade III or IV osteoarthritis was three times greater in patients under 65 than in a control population, and all but two affected patients also had erosion of subchondral bone in at least one affected joint. The excess of osteoarthritis was apparent in both the transplant recipients and those receiving haemodialysis. Over the age of 65 there was no significant difference in prevalence. Metabolic bone disease, including osteopenia, might contribute to the development of erosive osteoarthritis in chronic renal failure.
Behavioural consequences of partial beak amputation (beak trimming) in poultry.
1. The effects of beak trimming on 16-week-old Brown Leghorn hens, housed individually in battery cages, was assessed by comparing their behaviour after trimming with their behaviour before trimming and with the behaviour of a sham-operated control group. 2. In the short-term, times spent feeding, drinking and preening decreased. 3. In the long-term, times spent preening and pecking at the cage decreased and times spent standing inactive increased, with no signs of returning to pretreatment values after 5 weeks. 4. During the first three weeks, times spent feeding and drinking decreased and during the first two weeks, times spent sitting dozing increased, but after 5 weeks these had returned to near pre-treatment values. 5. It is argued that pain is the most probable cause of these behavioural changes. 6. The decrease in welfare to the individual bird caused by this pain will conflict with any increase in welfare to the flock brought about by beak trimming; this should be considered before any decision to beak trim is taken.
Is chronic renal failure a risk factor for the development of erosive osteoarthritis?
Erosive osteoarthritis of the hands of unusually early onset and severity was seen in two patients treated for chronic renal failure by long term haemodialysis and renal homograft respectively. The significance of this observation is discussed in the light of previous studies of erosive arthropathy in patients with chronic renal failure. Factors associated with chronic renal failure may predispose to the development of erosive osteoarthritis.
Rheumatoid arthritis and hereditary angioedema.
We describe a case in which rheumatoid arthritis (RA) developed in a patient with hereditary angioedema. Hereditary angioedema, one of the inherited complement deficiencies, has been reported in association with a number of autoimmune disorders, but there has been only 1 report of an association between RA and hereditary angioedema.
The welfare of farm animals: an ethological approach.
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Comparison of the stressfulness of harvesting broiler chickens by machine and by hand.
The procedures of manual and machine catching acted as short-term stressors, and induced a state of fear in 8-week-old broiler chickens. The heart rate of birds caught by both methods rose to similar high values but that of birds caught by machine returned to near normal rates more quickly, suggesting that they were less stressed. The duration of tonic immobility, a response which increases with fearfulness, was much longer in manually-caught birds. These results suggest that stress could be reduced and welfare improved by catching and picking up broiler chickens by a carefully designed machine, rather than by hand.
[Abnormal behavior in farm animals].
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Heart rate and laying behavior in two strains of domestic chicken.
The heart rates of caged hens, from two strains of domestic chicken (Gallus gallus domesticus), during the 20 min before and after oviposition were studied. Heart rates were measured using subcutaneously implanted radiotelemetry devices. In one strain, heart rate was low and relatively constant before laying, increased sharply at the moment of laying, and then decreased gradually during the post-laying period. Hens from this strain exhibited sitting behavior before laying. In contrast, in the other strain, heart rates increased steadily during the pre-laying period, peaked sharply at the moment of laying, and then declined during the post-laying period. Hens from this strain exhibited restless pacing behavior before laying.