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Abstract
The effect of some factors on maternal behaviour and litter traits in female NZW rabbits were studied, to determine the extent of these factors as stressors by measuring maternal serum cortisol level. The study was carried out in laboratory animal house ,in Faculty Of Veterinary Medicine Hospital, Assiut university, Assiut, Egypt, including the followings:
1. The effect of transient Doe-litter separation.
2. The effect of light/Dark cycle.
3. The effect of frightening.
4. The effect of water deprivation.
It was found that:
1. Serum cortisol level in pregnant and lactating rabbit was high during the last ten days of pregnancy and first fourteen days of lactation.
2. Diurnal changes of rabbits’ serum cortisol level were detected, where in (NPNL) and (PL) rabbits at 9 a.m. were 0.44 + 0.10 and 1.7 + 0.10 g/dL and significantly higher than that at 2 p.m. (0.71 + 0.07 and 1.85 + 0.03 g/dL),respectively.
The obtained results revealed the following:
(I) - Transient Doe-Litter Separation
1. Significant increase in serum cortisol level in DLS 24-h (when sampling after 24 h.) was estimated and equal to 3.23 g/dL.
2. No significant effect of DLS 4,8 and 24-h on post-partum behaviours could be achieved.
3. Abnormal behavioural patterns appeared only in does exposed to DLS 24-h.
4. A significant increase in maternal interest and maternal aggression were recorded due to DLS.
5. No significant effect of DLS on litter traits except that DLS 24-h that led to significant change in time of complete eye opening, exist of young out of nest box and nippling food.
(II) - Light/Dark period Cycle
1. 4-hL/20-hD cycle did not act as stressor as it led to significant decrease in serum cortisol value. While 24-hL/0-hD cycle acted as stressor as it led to a significant increase in serum cortisol level (2.25 g/dL).
2. Changing light/dark cycle affected some prepartum behaviours , postpartum behaviours ,maternal interest, maternal aggression, good mothering, appearance of some abnormal behavioural patterns and some litter traits.
(III) - Frightfulness
1. Frightening by rat as a mechanical stress and hairdryer as noisy emotional stressor in doe rabbits led to significant increase in serum cortisol level of 3.23 and 3.89 g/dL respectively.
2. Frightening by rat or hairdryer had a deleterious bad effect on prepartum behaviours.
3. Frightening by hairdryer led to significant increase in number of cold youngs and throwing food out of feed hoppers during lactation .
4. Frightening by a rat led to significant decrease in litter weaning weight and significant increase in mortality rat from 5th to 6th wk.
(IV) - Water deprivation
1. Water deprivation either during pregnancy or lactation acted as stress factor as it led to increase in serum cortisol value during last day of water deprivation period in both of water deprivation during pregnancy and lactation (4.00 and 3.0 g/dL respectively) ,serum cortisol level at day of parturition and increase in packed cell volume and dehydration of doe rabbits. Also it led to significant decrease in amount of food consumption and weight loss.
2. Water deprivation affected postpartum behaviours, some litter traits, maternal interest and maternal aggression and induced bad maternity.
3. Cannibalism appear as a result to water deprivation during pregnancy.
It is of interest to reveal that:
Only lighting for only 4-h led to decreasing the value of serum cortisol level at day of parturition at 2 p.m. (1.6 g/dL) to be near to that at 9 a.m. (1.30 g/dL).
The different pervious factors had no effect on the gestation period and mortality rate of does except water deprivation during pregnancy led to significant increase in mortality rate of does 66.67%.
Receptivity of doe rabbit affected badly by water deprivation during both pregnancy and lactation,continous lighting, lighting for only 4 h and frightening by hairdryer.
Conception rate affected badly by continous lighting , water deprivation during pregnancy and water deprivation during lactation.
Also, the previous factors did not affect the range of parturition time as all were occured 5 – 12 a.m. except lighting for only 4 h elongated the range to 5 a.m. – 6 p.m.