VARIATIONS IN CHIN-MARKING BEHAVIOR OF NEW-ZEALAND FEMALE RABBITS THROUGHOUT THE WHOLE REPRODUCTIVE-CYCLE

Chin-marking (chinning) was measured daily in intact New Zealand female rabbits across their whole reproductive cycle. In Experiment 1 does displayed during estrus (48 days studied) three phases, adaptation, growth and plateau, characterized by progressively higher chinning scores (mean±SE=3.6±1.1; 17.7±6.3; 26.6±4.9 marks/10 min, respectively). Despite great quantitative differences among individuals, these 3 phases and the occurrence of chinning "peaks" at 4-6 day intervals were consistently observed in all subjects (Ss). Mating provoked, within one hour, a dramatic decrease in chinning. Both pregnant and pseudopregnant Ss showed low chinning scores for the first 13 days after mating (combined mean±SE=7.3±3.8 marks/10 min). From days 14 to 30 postcoitus chinning gradually rose in the pseudopregnant Ss (mean±SE=12.7±5.4 marks/10 min) while remaining low in the pregnant ones (mean±SE=2.6±1.9 marks/10 min). Parturition allowed a gradual rise in chinning scores. In Experiment 2 the same Ss were explored across a second reproductive cycle that included lactation. In contrast to Experiment 1, no significant variations in chinning were displayed along estrus, Ss showing high chinning scores already on the first day of observation (mean±SE from 12 days=19.2±6.7 marks/10 min). In agreement with Experiment 1, mating drastically reduced chinning scores. Low levels were maintained throughout pregnancy (mean±SE=3.4±2.4 marks/10 min) and lactation (mean±SE=3.3±4.8 marks/10 min). Weaning allowed a gradual increase in chinning scores. The chinning pattern observed across two reproductive cycles closely parallels the sexual receptivity reported to occur in female rabbits under similar reproductive conditions. This coincidence allows us to propose that chin-marking may be a normal component of estrus and that its frequency may be used to assess the reproductive condition of female rabbits. © 1990.