Effects of bermuda grass (Cynodon dactylon cv. Coast cross) and rice hulls on growth performance of 30 day-old weaned rabbits

Several studies have demonstrated that rabbits can be maintained on diets containing high levels of Crude Fiber (CF) when compared to other monogastric animals. In the present study, we examined the effects of rice hulls and of bermuda grass (cv. Coast cross) on the growing performance of 30 day-old weaned rabbits. Rabbits were fed one of 5 diets containing rice hulls and/or bermuda grass as fiber source at the following proportions (BG/RH) 0/17.5, 15/11, 0/29, 14.7/19.1 and 48.5/0 for diets A, B, C, D and E, respectively. Body weight gain and voluntary feed intake were measured at 30, 44, 58 and 72 days. The time necessary to attain 2 kg of live body weight was not affected by the diets. However, daily weight gain differed significantly during the first two weeks after weaning among dietary groups. Diets C and D caused a lower body weight gain, probably because of the high level of Acid Detergent Fiber (ADF) in the diet (24 and 23). Voluntary feed intake increased with age in all treatments, but food intake was lower in treatments C and D when compared to animals receiving treatments B and E. The present results demonstrate that when rice hulls are used as fiber source, fiber must be given as ADF and not as CF because the difference between ADF and CF is enormous. Rice hull-containing diets balanced with CF give an inappropriate amount of components that seem to affect the growth performance of young animals.

Effects of post-training ß-endorphin and Met-enkephalin administration on two-way active avoidance task in well-nourished and protein malnourished rats

Protein malnutrition during suckling period or throughout the life affects the hypothalamic ß-endorphinergic system of adult rats. In the present study, rats were under nourished during suckling by feeding their dams an 8% casein diet whereas well-nourished dams recived a 25% casein diet from birth until weaning (21 day of postnatal life). After weaning, the offsprings were maintained with the same diet as their dams. When rats were 3 month-old, they were subjected to two-way active avoidance task. Protein malnutrition did not affect the performance in the two-way active avoidance task. Post-training ß-endorphin or Met-enkephalin administration impaired the retention of shuttle avoidance tast in both well-nourished and undernourished rats. However, the amnesic effect of the peptides was only achieved in undernourished rats with higher doses of apioids when compared to the well-nourished rats. These data suggest that undernourished rats present alterations in opioid sensitivity which may be related to changes in the levels of ß-endorphin previously observed both in brain and hypothalamus of early undernourished adults rats