Effects of lasalocid and cationomycin on the evolution of certain parameters in the blood plasma of sheep

Six adult sheep were fed at maintenance level, successively over three experimental periods, 1100 g of a roughage-rich diet without supplement or containing 33 mg kg-1 of lasalocid or cationomycin. The feed was administered in eight equal meals daily, every three hours. Blood samples were taken in each animal from the jugular vein at 10.00 hours, 16.00 and 22.00 hours, one hour after the animals were fed. The ionophores did not affect the plasma concentrations of glucose, free fatty acids, total amino acids, insulin, acetate, Ca or Mg. They decreased beta-hydroxy butyrate content (P < 0.05) and increased that of albumin (P < 0.05). Lasalocid alone significantly decreased uremia, but the significant threshold was only reached at 16.00 hours (P < 0.01). With this exception, the two ionophores had similar effects. Samples taken in peripheral blood appear to be too far from nutrient absorption sites to give a clear indication of the effects of these molecules on the products absorbed or metabolised in the digestive tract.

Effect of monensin on feed utilization and gastrointestinal fermentation in the hamster (Mesocricetus auratus)

Three experiments were conducted to examine the effect of monensin on growth performance, feed utilization and volatile fatty acids (VFA) in the forestomach and caecum of hamsters. In Expt 1, monensin was fed at levels of 0, 5, 10 and 20 mg/kg to the growing male and female hamsters given a commercial diet (major component: lucerne (Medicago sativa) meal). In Expt 2, monensin was fed at levels of 0, 5, 15, 45 and 135 mg/kg to the growing male hamsters given a semi-purified diet containing 10 g urea/kg (main components: maize starch, sucrose, casein and cellulose). In Expt 3, monensin was fed at levels of 0 and 40 mg/kg to the growing male hamsters given the commercial diet containing lucerne meal or a semi-purified diet. In Expt 1, monensin improved feed conversion efficiency and growth performances in the young growing hamsters, but monensin did not affect the hamsters at a later growing stage. In response to monensin the proportion of acetic acid increased and that of propionic acid decreased in the forestomach, whereas the proportion of acetic acid decreased and that of propionic acid increased in the caecum in Expt 2. The hamsters given 135 mg monensin/kg ate less, developed diarrhoea and died. The apparent digestibility of crude protein (nitrogen X 6.25) was improved by monensin but those of dry matter and neutral-detergent fibre (NDF) were decreased in hamsters given the semi-purified diet in Expt 3. Monensin did not appear to have a significant effect on the apparent digestibility of the diet containing lucerne meal. The responses to monensin in hamsters are compared with those in ruminants.

[Effect of the polyether antibiotic "monensin" on the rumen fermentation and fattening results of crossbreeding bulls of dairy cattle and fattening hybrids]

The influence of the polyether antibiotic Monensin on the rumen fermentation and the fattening results of fattening hybrids (genotype 61) and crossbreeding bulls of dairy cattle (genotype 19) was ascertained in two feeding experiments (E1 and E2). Caused by the supplementation of the antibiotic, the molar acetate quota decreased (1.9 to 4.8 Mol %) and the molar propionate concentration increased (0.2 to 2.9 Mol %) in the rumen fluid of crossbreeding bulls of dairy cattle and of fattening hybrids, it is, however, below the range described in literature. With the exception of the fattening hybrids in E1, the supplementation of Monensin resulted in the diminished intake of dry matter, the daily increase of the live weight of all groups of fattening bulls was higher (E1: fattening hybrids: 1106 resp. 1199g; crossbreeding bulls of dairy cattle: 1037 resp. 1058 g; E2: 997 resp. 1024 g; 895 resp. 981 g without resp. with Monensin). After the Monensin supplementation the crossbreeding bulls of dairy cattle showed a distinctly bigger decrease of the feed intake and a rise of the live weight increase than the fattening hybrids. For this reason the genotypes of dairy cattle showed in both experiments after the Monensin supplementation a bigger decrease of expenditure (0.8 resp. 7.1% and 5.6 resp. 11.3% in experiments 1 and 2) than the fattening hybrids.