Do goats have a salivary constitutive response to tannins?

Abstract

The effect of tannin-rich fodder (TRF) consumption on the saliva response of Criollo goats without previous browsing experience was determined. Eighteen kids were allocated into three treatments (n = 6 each): control group (CG), short-term tannin stimulus (TS) and long-term tannin stimulus (TL). Three experimental periods were used: adaptation (two weeks) in which the three treatment groups were fed Pennisetum purpureum grass and supplemented with a balanced feed. In period 1 (five weeks), TS and TL treatments were fed TRF (Lysiloma latisiliquum) with 55.5 g/kg DM condensed tannins (CT), grass and balanced feed. In period 2 (three weeks), L. latisiliquum fodder was withdrawn from the TS group. Thus, both the TS and the CG kids were only offered grass and balanced feed, while TL kids continued to receive TRF. In each period, saliva samples were collected to measure the tannin-protein interaction, salivary protein and protein turbidity index (PTI). The salivary protein was similar in all treatments and periods (P > .10). The goats' saliva reacted similarly when mixed with either tannic acid or L. latisiliquum water-acetone extract. Although the PTI tended to increase in the TL group compared to CG and TS with time, such difference was not significant. Thus, TRF intake failed to further increase the salivary response or PTI. Therefore, the saliva of goats from Yucatan, without previous browsing experience do have a constitutive response as it can block tannins irrespective of TRF stimulus. ARTICLE HISTORY

Salivary tannin‐binding proteins are a pervasive strategy used by the folivorous/frugivorous black howler monkey

“…We identified TBSPs using tannic acid (hydrolysable tannin) in the tannin‐binding assay; this compound binds readily PRPs in rodents (Glendinning, ) and it is used commonly as standard to show the tannin‐binding affinity of salivary proteins (Austin et al, ; Mau et al, ; Ventura‐Cordero, Sandoval‐Castro, Torres‐Acosta, & Capetillo‐Leal, ). We mixed samples of whole saliva (30 μl) with 10 μl of a tannic acid solution (0.5 and 2.5 μg/μl; Sigma–Aldrich, St Louis, MO) prepared in 50% methanol and then incubated and mixed the sample by continuously shaking for 6 hr at 4 °C (Austin et al, ).…”

Preference of goats (Capra hircus L.) for tanniniferous browse species available in semi‐arid areas in Ethiopia

“…The voluntary intake for a high tannin concentration could be attributed to the natural tendency of proline‐rich protein in the saliva of goats to attenuate the negative effects of tannins. Saliva of Criollo goats from Mexico (Ventura‐Cordero et al., ) and Damascus and Mamber goats of the Mediterranean region (Hanovice‐Ziony et al., ) exhibited tannin binding characteristics regardless of a prior tannin stimulus indicating that goats are naturally tolerant to relatively high level of tannins. Supplementation of PEG increased total browse species and hence tannin intake as found in previous studies with goats browsing on a tannin‐rich forage, Pistacia lentiscus L. (Decandia et al., ; Landau et al., ) as well as a quebracho tannin supplement in lambs (Titus et al., ).…”

“…A common adaptation to tannin ingestion in domestic and wild herbivores is increased secretion of proline‐rich proteins in saliva to form a complex with tannin (Shimada, ). Intrinsically, the saliva of goats is high in proline‐rich proteins regardless of previous exposure to tannins (Ventura‐Cordero et al., ). Another mechanism of herbivores is diet diversification, which also explains the trade‐off between ingesting nutritious feed and minimizing detrimental effects of PSM ingestion (Alonso‐Díaz et al., ).…”

Are there phylogenetic differences in salivary tannin‐binding proteins between browsers and grazers, and ruminants and hindgut fermenters?

“…Saliva samples were collected during the dry season when resources are limited for herbivores in African savannas and when mixed feeders typically shift to feed on more browse (i.e., woody vegetation, which is chemically defended) than grass (i.e., less chemically defended). We would expect that for mixed feeders that shift to use more woody vegetation than grass, there might be the potential for them to have inducible salivary tannin‐binding proteins, which they would likely be using during this time (Ventura‐Cordero, Sandoval‐Castro, Torres‐Acosta, & Capetillo‐Leal, 2017). To collect samples from wild herbivores, we collected saliva from 28 species during planned game‐capture and translocation activities across South Africa.…”

“…The resulting saliva tannin precipitate rings in the agar could then be compared to rings formed by the tannic acid stock solution alone as an indication of whether there was a difference between the amounts of tannins bound in each treatment (Bryant et al., 1991; Robbins, Hagerman, Austin, McArthur, & Hanley, 1991). For this experiment, we used a concentration of 1 g tannic acid per 100 ml, which was suspended in 70% acetone (Alonso‐Díaz et al., 2008; Ventura‐Cordero et al., 2017). Hagerman (2011) indicates that acetone‐containing extracts do not inhibit the precipitation reaction like other protein‐precipitating methods, so acetone can be used with this method.…”