RESUMEN
Aims: To evaluate the effect of aflatoxin B1 (AFB1) on in vitro dry matter disappearance (IVDMD), gas production and ammonia-N formation of an alfalfa hay based diet using batch culture system. Place and Duration of Study: Department of Animal Science, between July 2011 and August 2012. Methodology: In an anaerobic batch culture system, 50 ml of buffered rumen fluid was dispensed into a 125-ml serum bottle containing 0.5 g dry matter (DM) of the experimental diet. Experimental treatments included four dose levels of AFB1 (0, 300, 600 and 900 ng/ml). All bottles were purged with anaerobic CO2, sealed and placed in a shaking water bath for 72 h at 38.6ºC. Gas production of each bottle was recorded at 2, 4, 8, 12, 16, 24, 48 and 72 h of the incubation and then gas released. The batch cultures were repeated in three incubation runs. After 72 h incubation, bottles were opened and 2-ml sample of each bottle were taken for ammonia-N analysis. The biomass residues were centrifuged and the pellet was dried at 65°C for the determination of t he residual DM and IVDMD. Results: Addition of AFB1 affected the rate and cumulative gas production (P<0.05), so, by increasing the level of AFB1 from 0 to 900 ng/ml, the gas production rate decreased from 0.071 to 0.051 and cumulative gas production decreased from 196.4 to 166.0 ml/g DM, respectively. In addition, IVDMD decreased significantly with inclusion of AFB1 in culture medium, so that the lowest and the highest IVDMD values were observed in treatments with 900 and 0 ng/ml AFB1, respectively (0.54 vs. 0.68). The results indicated that addition of AFB1 significantly (P<0.05) decreased ammonia-N concentrations, so the lowest value was observed at 900 ng/ml AFB1. Conclusion: The addition of different levels of AFB1 affected in vitro fermentation characteristic, as represented in reduced gas production, dry matter digestibility and ammonia-N concentrations. Therefore it is necessary to control and manage aflatoxin contaminations in ruminants.
RESUMEN
Aims: To determine the effect of different levels of esterified glucomannan (EG) on detoxification and carryover of aflatoxin (AF) from feed to milk in lactating Holstein dairy cows. Study Design: The experiment was designed as a randomized block with twelve cows allocated to each treatment group. Place and Duration of Study: Department of Animal Science, Faroogh Life Sciences Research Laboratory, between July 2011 and August 2012. Methodology: Forty-eight lactating Holstein dairy cows were individually fed a similar based ration and randomly allocated to one of four levels of EG as the experimental treatments (0, 18, 27 and 36 g/cow daily of EG, named EG-0, EG-18, EG-27 and EG-36, respectively). Milk samples were collected on d 20 and 21 of experimental period to evaluate changes in milk AF concentration, milk AF secretion (milk AF concentration × milk yield); and AF transfer from feed to milk (AF secretion as a percentage of AF intake). Results: Feed intake and milk production were not affected by dietary treatments (P>0.05) and averaged 22.08 kg and 37.57 kg/d, respectively. Milk composition was also not affected (P>0.05) by addition of EG in the diet. Inclusion of EG to the diet was not effective in reducing milk aflatoxin M1 (AFM1) concentrations (P>0.05) and averaged 35, 40, 51 and 38 ng/kg for the EG-0, EG-18, EG-27 and EG-36, respectively. In addition, there was no significant difference (P>0.05) between the dietary treatments regarding AFM1 excretion and transfer of AF from feed to milk. Transfer of AF from feed to milk averaged 1.3, 1.47, 1.86 and 1.24% for the EG-0, EG-18, EG-27 and EG-36 treatments, respectively. Conclusion: Inclusion of EG up to 36 g/d (3 time more than recommended dosage) was not effective in reducing AFM1 concentrations, AF excretion, or AF transfer from feed to milk.