An in vivo trial was conducted in sheep to investigate the effect of three tropical tannin-rich plants (TRP) on methane emission, intake and digestibility. The TRP used were leaves of Glyricidia sepium, Leucaena leucocephala and Manihot esculenta that contained, respectively, 39, 75 and 92 g condensed tannins/kg DM. Methane was determined with the sulphur hexafluoride tracer technique. Eight rumen-cannulated sheep of two breeds (four Texel, four Blackbelly) were used in two 4 × 4 Latin square designs. Four experimental diets were tested. They consisted in a tropical natural grassland hay based on Dichanthium spp. fed alone (C) or in association with G. sepium (G), L. leucocephala (L) or M. esculenta (M) given as pellets at 44% of the daily ration. Daily organic matter intake was higher in TRP diets (686, 984, 1054 and 1186 g/day for C, G, L and M respectively; p < 0.05) while apparent organic matter total tract digestibility was not affected (69.9%, 62.8%, 65.3% and 64.7% for C, G, L and M respectively; p > 0.05). Methane emission was 47.1, 44.9, 33.3 and 33.5 g/kg digestible organic matter intake for C, G, L and M, respectively, and was significantly lower (p < 0.05) for L and M than for G and C. Our results confirm the potential of some TRP to reduce methane production. The strong decrease in methane and the increase in intake with TRPs may be due to their presentation as pellets.

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Mixed grazing systems combining sheep and cattle have shown better growth performance for one or both species. This observation has been attributed to their complementary feeding behaviour and the reduced host infection by gastrointestinal nematodes. Less attention has been paid to mixed grazing systems combining goats and cattle. Here, continuously grazing goats mixed with cattle (M) were compared with control goats reared alone (C) under tropical conditions. The comparison was conducted with gastrointestinal nematode-infected (I) and non-infected (nI) goats. Thus, the four treatments were cattle with gastrointestinal nematode-infected goats (MI), gastrointestinal nematode-infected goats alone (CI), cattle with non-infected goats (MnI) and non-infected goats (CnI). Average daily gain (ADG, g/day) and grass production were measured for the four groups of animals (six goats and two heifers treated with MI or MnI) grazing for 3 months on 4 subplots. Monthly measurements were performed over 5-day periods. This pattern was replicated in space for a second set of four subplots and in time for six successive cohorts of animals (bands 1 to 6). The ADG of goats in mixed grazing conditions was higher than controls irrespective of the infection status (32.6 v. 18.4 g/day for MI v. CI; 44.2 v. 33.5 g/day for MnI v. CnI). Concomitantly, the average biomass was lower for mixed grazing animals compared with controls (174 v. 170 for MI and MnI; 235 v. 208 for CI and CnI, respectively), suggesting better use of the sward. For daily BW gain (g/kg DM), mixed grazing also yielded better results than the control (1.88 v. 0.52 g BW/kg DM per day for MI v. CI; 2.08 v. 1.47 g BW/kg DM per day for MnI and CnI). Mixed grazing of goats and heifers offers a promising alternative for increasing goat and overall animal production as well as improving the management of pastures.Keywords: mixed grazing, BW, goat, agro-ecological management, tropical ImplicationsThis study conducted over 2 years showed a higher average daily gain of grazing goats pastured together with cattle compared with goats reared alone, considering either the individual gain or gain per hectare. This increased gain occurred irrespective of the infection status of the goats. Moreover, the biomass was lower in mixed grazing conditions, likely due to improved use of the pasture by goats that were mixed with cattle. These results suggest that integrated grazing could be employed as an alternative agroecological strategy to increase performance per hectare and control residual biomass. In addition, this strategy represents an important alternative to reduce the use of anthelmintics.

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-The effects of defaunation on growth and digestion were measured on sheep consuming four mixed diets (D1 to D4) of Digitaria decumbens grass and concentrate, with different protein to energy ratios. The protein digestible in the intestine (protein French feeding system, PDI) to energy (Forage unit, energy French feeding system) levels (P/E) in the diets were 80 (D1), 100 (D2), 120 (D3) and 140 (D4). Conventional and ciliate-free animals were conducted in parallel in 4 × 4 Latin square designs. First, two Latin square designs were conducted with 20 faunated lambs and 20 defaunated lambs to measure the average daily gain. In addition, two other Latin square designs were conducted with 8 conventional mature rams and 8 ciliate-free mature rams to measure digestion parameters. There was no effect of the diet on the average daily gain (ADG) of the lambs. The ADG of faunated lambs was significantly lower (P < 0.05) compared with defaunated lambs with the D2 diet (153.7 vs. 211.6, s.e. = 13.0 g·d -1 ). The feed conversion ratio was higher with conventional lambs compared with ciliate-free lambs with the D2 diet (7.2 vs. 4.7, s.e. = 1.6 g·g -1 , P < 0.05). The same trend was observed with the energy conversion ratio for the D2 diet (6.0 vs. 4.0, s.e. = 0.7 10 -3 UFL·g -1 , P < 0.05). The differences of ADG between conventional and ciliatefree lambs can be explained by the higher supply of protein in ciliate-free animals when the energy was not the first limiting factor for microbial and animal growth. Duodenal non-ammonia nitrogen (NAN) flow was significantly increased (P < 0.01) by defaunation (144 vs. 172, s.e. = 5.5 g NAN·d -1 ). However, the differences of NAN flow, observed between faunated and defaunated rams, were only significant (P < 0.01) with the D3 diet. The duodenal microbial N flow was significantly (P < 0.01) higher with ciliate free rams compared with conventional ones, consuming diets D2 and D3. A better microbial synthesis efficiency and a higher nitrogen digestion for the defaunated animals, explain the differences in nitrogen availability between the animals. Résumé -Les effets de la défaunation sur la digestion de rations mixtes (herbe de Digitaria decumbens et concentré) et la croissance de moutons. Quatre régimes mixtes (D1 à D4) composés de fourrage Digitaria decumbens et de concentré, différenciés par le rapport protéine / énergie dans le régime, ont été constitués. Le niveau de protéines digestibles dans l'intestin (Système PDI français) / énergie (UF, unité fourragère du Système français) de la ration (P/E) était de 80 (D1), 100 (D2), 120 (D3) et 140 (D4). Des animaux conventionnels et des animaux dépourvus de protozoaires ont été utilisés dans des dispositifs en carré latin 4 × 4 menés en parallèle. D'une part, deux dispositifs en carré latin ont été conduits avec 20 agneaux faunés et 20 agneaux défaunés afin de mesurer leur gain de poids moyen quotidien (GMQ). D'autre part, deux autres dispositifs en carré latin ont été conduits en parallèle avec 8 béliers adultes conventionnels et ...