Light intensity during rearing affects the behavioural synchrony and resting patterns of broiler chickens.

1. The effect of light intensity on behavioural synchrony and rest in broilers was investigated by randomly assigning 504 Cobb chicks to environmental chambers at low (5 lux), moderate (50 lux), or high (200 lux) daytime illumination under a 16 h L : 8 h D light cycle. We hypothesised that behavioural synchrony and resting behaviour would be affected by light : dark amplitude, and predicted that broilers reared at higher intensities would show increased synchrony and thus have fewer, but longer, resting bouts during the scotophase, since these bouts would be less likely to be interrupted by active birds. 2. Digital recordings were made for 48 h from weeks 3 to 5 of age, and scan samples taken of 11 behaviours at 15-min intervals. Z-scores for the amount of synchronisation were calculated using the kappa coefficient of agreement. Frequency and length of resting bouts and the number of resting bout interruptions by flockmates were also calculated from continuous observations of 4 focal broilers per pen. 3. Resting and sitting behaviour were significantly synchronised or showed a strong trend towards synchronisation in all treatments during the 3 weeks of observation. There were significant treatment differences in the degree of synchrony for preen, eat, rest and forage, with broilers reared in 200 lux showing the greatest degree of synchrony. 4. During the scotophase, broilers reared with high illumination had fewer, longer, and less interrupted bouts of resting than those reared with moderate or low illumination. During the photophase, broilers in the low-illumination treatment had more frequent, longer, and more interrupted resting bouts than those in the moderate or high illumination treatment. 5. In conclusion, rearing broilers under a 16 h L : 8 h D photoperiod with high daytime light intensity resulted in greater behavioural synchrony in the flock, with the potential to improve welfare by increasing uninterrupted resting behaviour during the dark phase.

Animal pain and distress in vaccine testing in the United States.

National statistics on animal use in research can provide guidance in setting priorities for research into alternative methods, i.e., those methods that can replace, reduce, or refine animal-based procedures. All else being equal, fields of research causing the most suffering to the largest numbers of animals should be considered prime candidates for alternative research. We examined national statistics on animal use in research in the United States to determine the extent to which vaccine testing accounts for those animals that experience unrelieved pain and distress. During 1998, 96,536 regulated animals were reported to have experienced unrelieved pain and distress in research (laboratory-bred mice and rats, as well as all non-mammals, are excluded from the U.S. reporting system). Vaccine-related testing alone accounted for 61% of this total. Of the 58,820 animals used in such vaccine testing, nearly all were hamsters (68%) and guinea pigs (28%), at least 74% were used in potency tests, and at least 55% were used in testing of Leptospira vaccine. This analysis and an earlier one both underscore the need to develop and implement alternative methods in vaccine testing.