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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 fedPennisetum purpureumgrass 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 In period 2 (three weeks),L. latisiliquumfodder was withdrawn from the TS group.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 orL. latisiliquumwater-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. [ABSTRACT FROM PUBLISHER]

We evaluated the effect of feeding dietary tannins from Lysiloma latisiliquum fresh forage on the saliva tannin-binding capacity of hair sheep lambs without previous exposure to tannin-rich (TR) fodder. Twenty-four hair sheep lambs (13.6±3.04 kg LW) were fed a tannin-free diet at the beginning of the experimental period (from day 10 to 13). On day 14, lambs were distributed into three groups (n=8): control group (CG), fed with the tannin-free diet (from D10 to D112); tannin short-term group (TST), fed the basal diet and 650 g of L. latisiliquum forage (from D14 to D55); tannin long-term group (TLT), fed the basal diet and 650 g of L. latisiliquum forage (from D14 to D112). Saliva samples were collected from the mouth of each lamb in the morning before feeding time on D10 and D14 (baseline period), on D49 and D56 (period 1) and on D97 and D112 (period 2). The tannin binding response of salivary protein (∆% turbidity) was determined with the haze development test (HDT) using either tannic acid or L. latisiliquum forage acetone extract. A turbidity protein index (TPI) was calculated as (∆% turbidity/[salivary protein (mg)]). Differences in HDT and TPI in the different groups were compared by repeated measures ANOVA using Proc Mixed. All groups had similar ∆% turbidity throughout the experiment (P>0.05). At baseline and period 1, the TPI of the different groups was similar (P>0.05). On period 2 the TLT group showed higher TPI compared with CG (P<0.05). Meanwhile, CG and TST showed similar salivary TPI. The saliva of hair sheep lambs consuming TR L. latisiliquum fresh fodder (TLT group) increased their TPI compared with control lambs not exposed to tannins. [ABSTRACT FROM PUBLISHER]

Sheep have been suggested to use their senses to perceive plant properties and associate their intake with consequences after ingestion. However, sheep with browsing experience do not seem to select against tannin-rich browsing materials in cafeteria trials. Thus, the objective of the present study was to evaluate the relationship between the chemical composition, selectivity index (SI), preference and intake rate (IR) of tannin-containing forage trees offered to sheep in cafeteria experiments. Four trees were selected for their condensed tannin content and their varying biological activities. Havardia albicans (high biological activity), Leucaena leucocephala (medium biological activity), Acacia gaumeri (low biological activity) and Brosimum alicastrum (very low biological activity) were used in this study. Ten hair sheep (23.7kg±1.43LW) with eight months of browsing experience in native vegetation were used in this study. Polyethylene glycol (PEG 3600MW) was administered to five sheep during all experiments. In experiment 1, fresh foliage from all trees was offered ad libitum for 4h. In experiment 2, B. alicastrum was withdrawn and the preference was determined again. The forage preference in experiment 1 was A. gaumeri (14.77gDM/kgLW)>B. alicastrum (11.77gDM/kgLW)>H. albicans (3.71gDM/kgLW)=L. leucocephala (1.87gDM/kgLW) (P<0.05). The preference in experiment 2 was A. gaumeri>H. albicans=L. leucocephala. PEG administration had no effect on the preference or IR. The intake rate seemed to have been affected by the plant density. Moreover, fiber compounds were found to be better predictors of DM intake than polyphenolic compounds at levels typically found in the evaluated forages. It was concluded that tannins and PEG did not modify the preferences of sheep in cafeteria trials. Thus, tannins are not involved in the preference regulation of animals with browsing experience., (Copyright © 2015 Elsevier Inc. All rights reserved.)