Effects of supplemental dietary tannins on the performance of white-tailed deer (Odocoileus virginianus)

Abstract

Tannins are natural and nutritionally significant components of the diets of browsing ungulates. In trials on supplemented pastures and in drylots, we estimated dry matter intake (DMI), weight gain, and urea N, potassium, cortisol and creatinine in urine of captive white-tailed deer fed pelleted diets that differed only in the respective quebracho tannin (QT) content. The low control, medium and high QT rations were 3.6, 63 and 152 g/kg DM respectively. There was no tannin-free pellet option. Trials were divided into winter pasture, restricted choice and spring growth. In winter pasture trial on pasture using QT, deer reduced QT intake relative to that expected under random foraging. This aversion was also apparent during the spring growth trial. While DMI in the winter pasture trial remained similar among treatments (p > 0.05), averaging 130 g/kg(0.75)/day, deer gained more weight (p < 0.05) when given a choice that included the high QT ration. During subsequent spring growth, DMI and weight gains generally exceeded those of the winter period. Unlike the winter pasture trial, weight gains in spring growth trial were higher (p < 0.05) in the low-control QT treatment. In the restricted choice trial, weight gain was again higher (p < 0.05) for deer fed a low-control QT diet. The urea N/creatinine ratio of deer fed the low-control QT diet (0.0357) was over three times that of deer fed the high QT diet (0.0107). Neither potassium/creatinine nor cortisol/creatinine ratios were affected by diet (p > 0.05). Collectively, these results suggest that although deer do not avoid tannins, and even ingested up to 5% under the choice options in these trials, the effect of tannins on deer performance may vary by season as well as by foraging opportunities.

Condensed Tannins' Effect on White‐Tailed Deer Forage Digestibility in Mississippi

“…Captive deer have been reported to increase intake of diets with 5% or 10% CT relative to CT-free diets and exhibit greater weight gain despite lower feed digestibility (Hudson et al 2000). Captive deer given free choice reportedly maintained diets unnecessarily high in CT (5.3% in winter, 3.4% in spring), and weight gain was not consistently related to CT concentration (Chapman et al 2009). Thus, within limits, CTs may actually benefit deer.…”

The complexity of interacting nutritional drivers behind food selection, a review of northern cervids

“…However, studies about the actual effects of PSM on the physiology of cervids are rare (Iason 2005). In recent years, PSM (mainly tannins) have also been shown to have some beneficial effects on the animal (Hoskin et al 2000, Makkar 2003), depending on, for example, season (Chapman et al 2010).…”

Moose selecting for specific nutritional composition of birch places limits on food acceptability

“…() and Robbins, Mole, Hagerman, and Hanley () found that condensed tannins reduce protein digestibility for ruminants. Subsequent studies have confirmed this (e.g., Hagerman & Robbins, ; Jones, Rude, et al., ; Spalinger, Collins, Hanley, Casara, & Carnahan, ) but also added nuances to the relationship: tannins may actually be beneficial at some concentrations (Clauss et al., ; Min, Barry, Attwood, & McNabb, ), and its influence on intake may differ with season (Chapman, Bork, Donkor, & Hudson, ) or concentrations of other nutrients in the diet (Villalba & Provenza, ). From the above references on moose and tannins, it seems that for each 1% increase in condensed tannin concentration, the digestibility of CP in shrubs or browse foliage is reduced by 2.5%.…”