Preliminary study on the effects of ammonium nicotinate on in vitro ruminal fermentation as determined using rumen simulation technique (Rusitec)

Abstract

The objective of the present in vitro study was to investigate the effects of different dietary supplementation levels of ammonium nicotinate (NA-NH4), a precursor product when manufacturing nicotinic acid (NA), on ruminal fermentation traits. Four experimental runs were carried out incubating ruminal fluid from a donor cow by using rumen simulation technique (Rusitec). A low-protein (109 g/kg feed dry matter) basal diet, consisting of maize silage, hay and concentrate, served as the first control. Supplements were NA at 4.7 mg/day (second control), NA-NH4 at supplementation rates of 2.7, 5.4, 10.7 and 21.4 mg/day, or NH4-sulfate at 2.53 mg/day (the third control). All NA-containing treatments were supplemented with the same amount of sulfate as supplied with the third control treatment. None of the NA-supplements affected any of the fermentation traits significantly compared with the first control treatment, except for a decrease in total short-chain fatty acids at the highest supplementation rate of NA-NH4. No differences were found between the treatments containing the same amount of NA, i.e. the second control and the NA-NH4 treatment at 5.4 mg/day. Comparing the different NA-NH4 supplementation rates revealed that 5.4 mg/day of NA-NH4 resulted in a lower amount of nitrogen (N) recovered in ammonia than the highest NA-NH4 supplementation rate, and increased non-ammonia N. The findings confirmed the suitability of NA-NH4, instead of pure NA, as a feed supplement; however, increasing NA-NH4-supplementation above the typical rate for dairy cattle might negatively affect ruminal fermentation.