In vitro Effect of Increasing Levels of Natuzyme® on Fermentation Responses of Corn Silage Based Diet.

Aims: To evaluate the in vitro effect of an exogenous commercial enzyme blend (Natuzyme®) on fermentation responses and methane production of corn silage based diet. Study Design: Completely randomized design. Place and Duration of Study: Department of animal science, Faculty of agriculture, Ferdowsi University of Mashhad, between November 2012 and March 2013. Methodology: Two hundred fifty mg of milled and dried corn silage based diet in 3 runs and four replicates was weighed into 125-ml serum bottles for an in vitro gas production trial. A solution of a commercial enzyme blend (Natuzyme®) was added 12 hour prior to commence of the incubation (96 h) to make treatments of 1.68 and 2.52 (g/kg). No added enzyme bottles were considered as control. Gas production parameters at 96 h incubation were estimated and half time of gas production (t1/2) was calculated. Another gas test was run according to t1/2. All the incubations for each treatment were terminated at t1/2 and gas and methane volume recorded. Apparent dry matter degradability was assessed by centrifugation and ml methane per mg dry matter apparently degraded was calculated. Results: Gas production parameters were not affected by addition of the enzyme blend. Supplementation of a corn silage based diet with the enzyme as 1.68 or 2.52 g/kg dry matter of the diet increased apparent dry matter degradability by 21% compared with control. Gas production, methane volume and volume of methane per mg of dry matter apparently degraded were not influenced by incrementing level of Natuzyme®. Conclusion: Natuzyme® at the doses applied in the current experiment was capable of improving apparent dry matter degradability of corn silage based diet.

Effect of Aflatoxin B1 on in vitro Rumen Microbial Fermentation Responses Using Batch Culture.

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.

Effect of Esterified Glucomannan on Carryover of Aflatoxin from Feed to Milk in Lactating Holstein Dairy Cows.

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.