Abstract
Simple SummaryThe main challenge faced by cows during the first three weeks after calving is the sudden increase in nutrient demand for milk production while dry matter intake and nutrient supply lag. Although metabolic hormone changes are a normal adaptive process in high yielding cows, failure to adapt to this challenge can lead to disease states and affect production and reproductive efficiency. Therefore, a smooth transition from prepartum to postpartum period for optimal dairy cow health and performance. Whether rumen-protected niacin supplementation could be a useful additive was controversial. This work tested whether the widespread use of rumen-protected niacin in multiparous Holstein dairy cows could be justified.Extensive studies about rumen-protected niacin (RPN) supplementation on dairy cows in early-lactation have been done, but the effects of RPN on changes in dry matter intake (DMI), milk production, feed digestibility, and fecal bacterial community were conflicting. The aim of this study was to investigate them affected by RPN in postpartum cows. Multiparous Holstein dairy cows (n = 12, parity = 3.5 ± 0.5, body weights = 740 ± 28 kg) were divided into two groups supplemented with either 0 (CON) or 20 g/d RPN (RPN). Our results showed that RPN supplementation increased DMI and milk production of cows during the first three weeks after calving (p < 0.05). The concentrations of neuropeptide Y and orexin A were significantly higher in RPN group than that in the CON group during postpartum period (p < 0.05). The apparent total-tract digestibility of nutrients was similar between the CON and RPN groups at 2 weeks after calving (p > 0.05). The 16S rRNA gene sequencing analysis showed that RPN had no impact on the alpha and beta diversity, although 4 genera were changed in cow feces at 14 days after calving. Overall, 20 g/d RPN added to the diet could improve DMI and milk yield up to two weeks after calving with little influence on feed digestibility.
Highlights
As for farmed animals, the health and biological functioning of dairy cattle are often prioritized
A total of 12 multiparous Holstein dairy cows were divided into two groups with diet supplemented with either 0 (CON) or 20 g/day rumen-protected niacin (RPN) (RPN), each group contained three
dry matter intake (DMI), the concentration of NPY and orexin A (OXA), milk production, and milk protein yield were higher in RPN than that in CON (p ≤ 0.001) during the first three weeks after calving
Summary
As for farmed animals, the health and biological functioning of dairy cattle are often prioritized. Despite the action of homeostatic mechanisms to maintain blood parameters within physiologic levels, changes in metabolites and hormones occur as a result of increased metabolic demands in lactating animals. These changes are not necessarily indicative of diseases but make animals physiologically unstable and more susceptible to a number of metabolic diseases at this stage than during other life periods compromising productivity [4]. These repercussions highlight the need for a smooth transition from prepartum to postpartum period for optimal dairy cow health and performance. The improvement of diet composition becomes a key factor to improve the health status and welfare of animals [5], as well as to enhance productivity in livestock [6,7,8]
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