In vitro organic matter digestibility and gas production of fish-meal coated with fat
In this study, an in vitro rumen gas production technique was utilized to evaluate fish-meal coated with different types and levels of fats for total gas production, Metabolizable energy (ME) and organic matter digestibility (OMD) contents. Approximately 200 mg of sample was weighed and inserted in glass syringes, then mixed with the inoculum and artificial saliva, incubated at 39 °C in a ventilated oven and gas production (GP) was recorded after zero to 96 h of incubation. There were differences among different fat coated fish-meals and uncoated fish-meal (FM) in total GP at 12, 24, and 48 h of incubation, and the treatments differed (P<0.01) in rate of, and potential, gas production.
The result of the present study showed that experimental fats which mixed by fish-meal, reduced in vitro digestibility of organic matter and GP during the time of incubation. In compare to hydrogenated palm oil (HP), coating fish-meal with hydrogenated tallow (HT) resulted in significant reduced GP (P<0.01). Furthermore the values of b and a+b reduced significantly since fish-meal coated with both types of fat in comparison to uncoated fish-meal (P<0.01). It seems that one of the possible strategies to reduce total GP from dairy cows is coating some portions of dietary concentrate with supplemental fats in the form of hydrogenated fats like HT or HP.
Keywords: fish-meal; gas production; hydrogenated tallow; hydrogenated palm oil, fat coating.