Tropical tannin-rich fodder intake modifies saliva-binding capacity in growing sheep

Fatty acid metabolism in lambs supplemented with different condensed and hydrolysable tannin extracts

Five groups of lambs (n = 9 each) were used to test the effect of plant extracts rich in hydrolysable (HT) or condensed tannin (CT) on animal performance, fatty acid composition of rumen content, liver and meat. The control group (CO) received a concentrate-based diet without tannins supplementation. The other groups received the same diet as the control lambs plus 4% chestnut (CH) and tara (TA) extracts as a source of HT and mimosa (MI) and gambier (GA) extracts as a source of CT. One-way ANOVA was used to assess the overall effect of dietary treatments, tannins supplementation (CO vs. CH+TA+MI+GA) and the effect of tannin type (HT vs. CT: CH+TA vs. MI+GA) on animal performance, rumen content, liver and intramuscular FA. Dietary CH negatively affected animal performance. The rumen content of the different groups showed similar levels of 18:3 c9c12c15, 18:2 c9c12, 18:2 c9t11, 18:1 t11 and 18:0, whereas 18:1 t10 was greater in CO. Also, 18:1 t10 tended to be lower in the rumen of HT than CT-fed lambs. These data were partially confirmed in liver and meat, where CO showed a greater percentage of individual trans 18:1 fatty acids in comparison with tannins-fed groups. Our findings challenge some accepted generalizations on the use of tannins in ruminant diets as they were ineffective to favour the accumulation of dietary PUFA or healthy fatty acids of biohydrogenation origin in the rumen content and lamb meat, but suggest a generalized influence on BH rather than on specific steps.

Gymnopodium floribundum fodder as a model for the in vivo evaluation of nutraceutical value against Haemonchus contortus

This study validated a protocol to identify the nutraceutical value of Gymnopodium floribundum (GF) foliage based on its effects on sheep nutrition, production and health and its impact on adult Haemonchus contortus. Thirty animals (17.8 ± 3.44 kg BW) were distributed into five experimental groups (n = 6). Groups T1-T3 received feed including 20%, 30% and 40% GF content, respectively, and group T4 received feed with 0% GF. Groups T1-T4 were all infected with 6000 H. contortus infective larvae (L₃). Group T5 included six worm-free lambs fed a diet without GF. Feed intake, dry matter digestibility (DMD) and organic matter digestibility (OMD) were measured, in addition to the faecal excretion of eggs per gram (EPG) and total faecal egg count (TFEC) of H. contortus. On day 39 post-infection, lambs were humanely slaughtered to recover and count adult parasites and assess the length and fecundity of female worms. Higher levels of GF in the diet reduced DMD and OMD (P < 0.05), with the lowest values in T3 (40% GF) (P < 0.05). Body weight gain was similar for all groups (0.18 to 0.2 kg/day; P > 0.05). EPG and TFEC were lower in T1 and T3 than in T4 (P < 0.05), and the number of adult female worms was lowest in T3 (P < 0.05). In conclusion, GF leaf meal can be considered a nutraceutical when included at 40% (T3) in the diet of lambs, based on its ability to decrease the EPG and TFEC of H. contortus by reducing the female worm burden. A 40% inclusion level had no negative impact on lamb diet intake, production and health, although a reduction of digestibility was observed.

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

Dietary tannins can affect protein digestion and absorption, be toxic, and influence food selection by being astringent and bitter tasting. Animals that usually ingest tannins may regularly secrete tannin-binding salivary proteins (TBSPs) to counteract the negative effects of tannins or TBSPs production can be induced by a tannin-rich diet. In the wild, many primates regularly eat a diet that contains tannin-rich leaves and unripe fruit and it has been speculated that they have the physiological ability to cope with dietary tannins; however, details of their strategy remains unclear. Our research details the salivary protein composition of wild and zoo-living black howler monkeys (Alouatta pigra) feeding on natural versus manufactured low-tannin diets, and examines differences in TBSPs, mainly proline-rich proteins (PRPs), to determine whether production of these proteins is dependent on the tannin content of their food. We measured the pH, flow rate, and concentration of total protein and trichloroacetic acid soluble proteins (an index of PRPs) in saliva. Howler monkeys produced slightly alkaline saliva that may aid in the binding interaction between tannin and salivary proteins. We used gel electrophoresis to describe the salivary protein profile and this analysis along with a tannin-binding assay allowed us to detect several TBSPs in all individuals. We found no differences in the characteristics of saliva between wild and zoo-living monkeys. Our results suggest that black howler monkeys always secrete TBSPs even when fed on foods low in tannins. This strategy of constantly using this salivary anti-tannin defense enables them to obtain nutrients from plants that sometimes contain high levels of tannins and may help immediately to overcome the astringent sensation of their food allowing howler monkeys to eat tanniferous plants.

Tannin containing legumes as a model for nutraceuticals against digestive parasites in livestock

Parasitic infections with gastrointestinal nematodes (GINs) still represent a worldwide major pathological threat associated with the outdoor production of various livestock species. Because of the widespread resistance to synthetic chemical anthelmintics, there is a strong impetus to explore novel approaches for a more integrated management of these infections. The use of nutraceuticals in the control of GINs is one of the alternatives which has been widely studied for 20 years. The objectives of this review are: (i) to define and illustrate the concept of 'nutraceutical' in the context of veterinary parasitology based on data obtained on the most studied models to control GINs in small ruminants, the tannin-containing legumes (Fabaceae); (ii) to illustrate how the 'nutraceutical concept' could be expanded to other plants, other livestock production systems and other GI parasitic diseases, and (iii) to explain how this concept is opening up new research fields for better understanding the interactions between the host, the digestive parasites and the environment.

Ruminant self-medication against gastrointestinal nematodes: evidence, mechanism, and origins

Gastrointestinal helminths challenge ruminants in ways that reduce their fitness. In turn, ruminants have evolved physiological and behavioral adaptations that counteract this challenge. Ruminants display anorexia and avoidance behaviors, which tend to reduce the incidence of parasitism. In addition, ruminants appear to learn to self-medicate against gastrointestinal parasites by increasing consumption of plant secondary compounds with antiparasitic actions. This selective feeding improves health and fitness. Here, we review the evidence for self-medication in ruminants, propose a hypothesis to explain self-medicative behaviors (based on post-ingestive consequences), and discuss mechanisms (e.g., enhanced neophilia, social transmission) that may underlie the ontogeny and spread of self-medicative behaviors in social groups. A better understanding of the mechanisms that underlie and trigger self-medication in parasitized animals will help scientists devise innovative and more sustainable management strategies for improving ruminant health and well-being.