Niacin for dairy cattle: a review

Abstract

Due to the incorporation of niacin into the coenzymes NAD and NADP, niacin is of great importance for the metabolism of man and animals. Apart from niacin in feed and endogenous formation, microbial niacin synthesis in the rumen is an important source for dairy cows. But the amount synthesised seems to differ greatly, which might be influenced by the ration fed. Many studies revealed a positive impact of a niacin supplementation on rumen protozoa, but microbial protein synthesis or volatile fatty acid production in the rumen showed inconsistent reactions to supplemental niacin. The amount of niacin reaching the duodenum is usually higher when niacin is fed. However, not the whole quantity supplemented reaches the duodenum, indicating degradation or absorption before the duodenal cannula. Furthermore, supplementation of niacin did not always lead to a higher niacin concentration in blood. Effects on other blood parameters have been inconsistent, but might be more obvious when cows are in a tense metabolic situation, for example, ketosis or if high amounts are infused post-ruminally, since ruminal degradation appears to be substantial. The same is valid for milk parameters. In the few studies where blood niacin and milk parameters have been investigated, enhanced niacin concentrations in blood did not necessarily affect milk production or composition. These results are discussed in the present review, gaps of knowledge of niacin's mode of action on the metabolism of dairy cows are identified and directions for future research are suggested.

Effects of niacin supplementation (40 weeks) and two dietary levels of concentrate on performance, blood and fatty acid profiles of dairy cattle

“…In addition, taking cows and heifers together, the animals were in a less pronounced negative energy balance, so no effect was found on milk yield or FCM yield. This is in agreement with Niehoff et al (2009a), who concluded that the absence of a niacin effect could be explained because the cows were too far into lactation, and thus not in a negative energy balance , as in the present trial when cows and heifers were evaluated together. If they were considered separately, it could be seen that the cows had entered a negative balance (Figure 7), owing to their higher milk performance.…”

“…In the present study niacin had no effect on milk fat content. In most studies reviewed by Niehoff et al (2009a), no effect was found for milk fat yield or milk protein content or yield. Differing from this, Belibasakis & Tsirgogianni (1996) found increased fat concentration and yield due to niacin (10 g/d); Erickson et al (1992) found milk protein concentration increased (12 g NA/d); while Drackley et al (1998) found it decreased (12 g/d).…”

“…However, there is a dearth of studies of the long-term effects on dairy cows of high doses of niacin supplementation with different concentrate proportions. It was found that concentrate level (18% -60%) with a low level of niacin supplementation (6 -12 g/d/cow) in the diet influences the fate of supplemental niacin and the rate of ruminal niacin production or degradation, and therefore the mode of action of niacin supplementation (Niehoff et al, 2009a). Thus, the aim of the present study was to investigate the effects of high doses of niacin supplementation with two concentrate levels over an entire lactation period.…”

“…Moreover, in humans NAM is a weak agonist to the receptor (HM74A), which exerts an antilipolytic action after stimulation with NA (Wise et al, 2003). Niehoff et al (2009a) noted that there is disagreement about the existence of NA in blood. Supplemented niacin is rapidly converted to NAD and then hydrolysed to NAM.…”

Determining in vivo ruminal stability of three ruminally protected nutrients in lactating Jersey cows

“…Animal requirements for some nutrients may be much higher than previous estimates based upon concentrations in their diets and microbial biomass (Santschi et al, 2005). As most supplemental AA and water soluble vitamins have been shown to be extensively degraded in the rumen (Niehoff et al, 2009;Zimbelman et al, 2010), dietary supplementation without rumen protection is a very inefficient nutrient delivery mechanism to the intestinal absorptive site.…”