Abstract
This study was conducted to investigate effects of supplementing two doses of quebracho tannins (QT; 100 or 200 g/cow/d; QT100 or QT200) pre and post parturition to thirty Holstein dairy cows on Dry Matter Intake (DMI), milk yield and composition, blood metabolites and reproductive performance for 12 weeks. There were no significant changes in DMI due to QT at transition period of dairy cows. QT supplementation at either level decreased (P 0.05) the total number of ovarian follicles, number of large follicles, diameter of largest follicle, number of small follicles, number and diameter of corpus luteum, and progesterone concentration. The inclusion of QT increased days open and number of services per conception, which consequently decreased conception rate, compared to the control cows. QT100 decreased (P < 0.05) serum total protein, globulin, glucose and triglycerides concentrations as compared with their values in control cows. Thus, the supplementation of commercial QT to dairy cows at their transition period had negative impacts on productive and reproductive performance.
Highlights
One of the common feed additives is antibiotics, e.g., monensin, which is fed to the animals to prevent disease and metabolic disorders, improve Feed Efficiency (FE) and reduce energy and protein losses in the rumen
The results revealed non-significant changes (P > 0.05) on Dry Matter Intake (DMI) due to quebracho tannins (QT) supplementation at the transition period of dairy cows
Effects of tannins are directly dependent upon their quantitative presence in legumes, but there are differences among tannins depending on their reactivity which is related to their chemical nature and the type of association with the substrate [26]
Summary
One of the common feed additives is antibiotics, e.g., monensin, which is fed to the animals to prevent disease and metabolic disorders, improve FE and reduce energy and protein losses in the rumen. The European Union Directive EC 1831/2003 provided an opportunity to exploit plants, plant extracts and plant secondary metabolites (i.e., tannins, essential oils, saponins, flavonoids) as natural alternatives to enhance livestock productivity and reduce their impact on the environment by reducing environment pollutants such as methane (CH4) in fermentation gases, as well as P and N in manure [3]. Most of PSC possess biological activity on the microorganisms, i.e. they affect some animal metabolic processes and/or the growth rate of some microorganisms [4]. For this reason, drug and animal nutrition companies routinely screen bioactive compounds of plants in order to obtain new drugs or feed additives [5]
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