Relationship between cytologic changes in bronchoalveolar lavage fluid and weight gain in calves with gastrointestinal nematodes and lungworms

Two of three groups of 10 calves each were infected with either 100,000 infective larvae (L3) of Ostertagia spp. and 100,000 L3 of Cooperia spp. or with 4000 L3 of Dictyocaulus viviparus, respectively, at the age of 14 weeks. The third group was not infected. After treatment with an anthelminthic five calves from each group were challenged with either 100,000 L3 of Ostertagia spp. and 100,000 L3 of Cooperia spp. or 4000 L3 of Dictyocaulus at the age of 20 weeks. The calves were 25 weeks old when slaughtered. Total and differential cell counts were determined in bronchoalveolar lavage fluid and showed that neutrophils were the most frequent and eosinophils the least frequent cell present. There was a significant negative relationship between eosinophil levels and weight gain of the calves.     

The influence of dietary cation-anion differences on acid-base balance,food intake,growth and nutrient utilisation of juvenile African catfish Clarias gariepinus (Burchell)

A study was conducted to examine the effect of dietary cation-anion difference (CAD, Na⁺+K⁺-Cl^–, mEq kg ^–1) on acid-base balance, food consumption and growth of juvenile African catfish, Clarias gariepinus. Four dietary CAD levels (-100, 100, 500, 700 mEq kg^–1) were established by altering levels of NaHCO₃, CaCl₂ and NH₄Cl in the diets. The group fed the diet of excess anions (CAD: -100 mEq kg^–1) had low food consumption and growth rate. Food consumption and growth increased linearly with an increase in dietary CAD within the range -100 to 700 meq. kg^–1. Blood pH was not significantly influenced by dietary CAD. A quadratic relationship between Na⁺, Cl^– and CAD level in plasma and dietary CAD was found. Body composition of fish and nitrogen/energy utilisation efficiency differed between dietary CAD treatments. The results suggest that dietary CAD influence acid-base regulation and thus the energy costs for maintaining homeostasis. The increased food intake and growth performance of C. gariepinus at higher CAD levels may be related to a reduced maintenance costs for homeostasis.     

Metabolic costs of changing the cation–anion difference in the diet of juvenile African catfish Clarias gariepinus (Burchell)

The influence of dietary cation–anion difference (CAD, Na⁺ + K⁺– Cl^–, mEq kg^–1) on energy metabolism and nitrogen losses in juvenile African catfish Clarias gariepinus (Burchell) was examined in fish exposed to different dietary CAD levels (–146, 116, 497, 713 and 828 mEq kg^–1 diet). The experiment was conducted in open circuit balance respiration chambers over a 3-week period. Five 24-h monitoring periods were carried out at 3-day intervals during the experimental period with O₂ consumption, ammonia and nitrate + nitrite (NO_x) and CO₂ production being measured at 5-min intervals for each chamber. The negative dietary CAD (–146 mEq kg^–1) resulted in the highest energy expenditures (83 kJ kg^–0.8· d^–1). With increasing dietary CAD levels, heat loss gradually decreased to minimum values of 56 kJ kg^–0.8 day^–1 at a dietary CAD level of 713 mEq kg^–1. Consequently, metabolizable energy utilization efficiency (MEU, percentage of retained energy over metabolizable energy) quadratically ( P  < 0.05) increased and reached a maximum at a dietary CAD of 713 mEq kg^–1.     

The Development of a Functional Digestive System in the African Catfish Clarias gariepinus (Burchell)

The morphological and physiological development of the intestine, stomach, liver and pancreas of the African catfish, Clarius guriepinus (Burchell 1822), was investigated from hatching until 9 days after the start of exogenous feeding by histological, histochemical and immunohistochemical procedures. During the yolk sac period, lasting 48 hours at 30 C, the digestive system develops from a rather undifferentiated system into a distinct liver and pancreas and a segmented intestine (parts I to III). Insulin and glucagon producing cells were clearly found in the endocrine pancreatic islets from 14 hours after hatching onwards, while at the start of exogenous feeding, the exocrine pancreas showed an intense zymogen colouration. Exogenous feeding started three days after fertilization, i.e., 48 hours after hatching. At that moment, the rearing temperature was lowered to 27.5 C. The first day of feeding was referred to as day zero, changing into day 1 when the first 24 hours of feeding were completed. From the start of exogenous feeding onwards, aminopeptidase, non-specific esterase and ATP-ase were detected in the digestive system. Morphologically, the stomach was completed at day 4 of exogenous feeding. Gastric acid secretion started on day 4 and lead to a pH below 3.3 in the stomach on day 5. During the first four days of exogenous feeding, C-t-gastrin immunopositive cells were found throughout the gut, including the gastric epithelium. After day 4, the C-t-gastrin cells were only detected in the anterior intestine. The completeness of the stomach development was also marked by the appearance of non-specific esterase activity in the stomach epithelial cells on day 5. All data together clearly indicate that in Clarius gariepinus , the ontogeny of a functional digestive system has been completed on day 5 after the start of exogenous feeding, marking thereby the end of the larval period.