Effect of different weaning age (21, 28 or 35 days) on production, growth and certain parameters of the digestive tract in rabbits

摘要

The effect of different weaning ages, that is, 21 (G21), 28 (G28) or 35 (G35) days, on growth and certain parameters of theuddigestive tract was examined in rabbits to assess the risk of early weaning attributable to the less-developed digestive system.udOn days 35 and 42, G35 rabbits had 10% to 14% and 10% higher BW, respectively ( P,0.05), than those weaned at days 21 andud28. In the 4th week of life, early weaned animals had 75% higher feed intake than G28 and G35 rabbits ( P,0.05). The relativeudweight of the liver increased by 62% between 21 and 28 days of age, and thereafter it decreased by 76% between 35 andud42 days of age ( P,0.05), with G21 rabbits having 29% higher weight compared with G35 animals on day 35 ( P,0.05).udThe relative weight of the whole gastrointestinal (GI) tract increased by 49% and 22% after weaning in G21 and G28 rabbits,udrespectively ( P,0.05). On day 28, the relative weight of the GI tract was 19% higher in G21 than in G28 rabbits, whereas on dayud35 G21 and G28 animals had a 12% heavier GI tract compared with G35 rabbits ( P,0.05). Age influenced the ratio of stomach,udsmall intestine and caecum within the GI tract; however, no effect of different weaning age was demonstrated. The pH value ofudthe stomach and caecum decreased from 5.7 to 1.6 and from 7.1 to 6.3, respectively, whereas that of the small intestine increasedudfrom 6.8 to 8.4 ( P,0.05); the differences between groups were not statistically significant. Strictly anaerobic culturable bacteriaudwere present in the caecum in high amounts (108), already at 14 days of age; no significant difference attributable to weaning ageudwas demonstrable. The concentration of total volatile fatty acids (tVFA) was higher in G21 than in G28 and G35 throughout theudexperimental period ( P,0.05). The proportion of acetic and butyric acid within tVFA increased, whereas that of propionic aciduddecreased, resulting in a C3 : C4 ratio decreasing with age. Early weaning (G21) resulted in higher butyric acid and lower propionicudacid proportions on day 28 ( P,0.05). No interaction between age and treatment was found, except in relative weight of the GIudtract and caecal content. In conclusion, early weaning did not cause considerable changes in the digestive physiologicaludparameters measured, but it resulted in 10% lower growth in rabbits.