1Facultad de Medicina Veterinaria y Zootecnia,Universidad Autónoma de Yucatán,Km 15.5 Carretera Mérida- Xmatkuil 97315 Mérida,Yucatán,Mexico.
Animal. 2018 Jun;12(6):1269-1276. doi: 10.1017/S1751731117002634. Epub 2017 Oct 26.
Previous cafeteria studies suggested that a moderate natural gastrointestinal nematode (GIN) infection did not modify the resource selection of adult Criollo goats towards tannin-rich plants compared with worm-free goats. A higher infection with Haemonchus contortus could trigger a change in the resource selection behaviour towards tannin-rich foliage. Alternatively, goats might select plant species solely to meet their nutritional requirements. A cafeteria study investigated the effect of a high artificial infection with H. contortus on the feed resource selection of goats. Adult Criollo goats (37.5±4.8 kg BW) with browsing experience were distributed in two groups: the infected group (IG) with six animals artificially infected with H. contortus (6000 L3/animal); and the non-infected group (NIG) with six animals maintained worm-free. The experiment included two 5-day periods with additional 5-day adaptation period. In the first period, animals were offered foliage of five plant species with a decreasing gradient of condensed tannins (CT) (Mimosa bahamensis, Gymnopodium floribundum, Havardia albicans, Acacia pennatula, Lysiloma latisiliqum), and three plant species with negligible CT content (Leucaena leucocephala, Piscidia piscipula and Brosimum alicastrum). In the second period the foliage of B. alicastrum was withdrawn. A grain-based concentrate feed was offered daily at 1% BW in DM basis. Dry matter and nutrient intake was determined. Foliage selection of each experimental group was determined using the Chesson selection index. The H. contortus egg count per gram of faeces (EPG) was determined for infected goats twice daily. Chesson index showed a similar pattern of foliage selection on periods 1 and 2. Mean EPG of goats in IG was 2028±259 EPG during period 1 and 1 293±198 EPG during period 2 (P>0.05). During period 1, the selection pattern was highest for B. alicastrum (tannin-free), followed by a tannin-rich plant (M. bahamensis). These two plants remained as highly selected during period 2. The Chesson index showed that both experimental groups (IG and NIG) selected the same plant species in both periods. Thus, a high H. contortus infection did not affect selection of goats fed with CT-rich plants. Apparently, goats balanced their nutrient intake with the plants selected, showing evidence of nutritional wisdom. This balance may have helped to prevent excess protein in the diet and also to maintain a low GIN infection, both considered as examples of prophylactic self-medication.
先前的自助餐厅研究表明，与无蠕虫的山羊相比，适度的天然胃肠道线虫（GIN）感染不会改变克里奥尔成年山羊对富含单宁植物的资源选择。较高的感染旋毛虫可能会引发对富含单宁的叶子的资源选择行为的变化。或者，山羊可能会仅仅选择植物物种来满足其营养需求。自助餐厅研究调查了高人工感染旋毛虫对山羊饲料资源选择的影响。具有浏览经验的成年克里奥尔山羊（37.5±4.8 kg BW）分为两组：感染组（IG），六只动物人工感染旋毛虫（6000 L3/动物）；和非感染组（NIG），六只动物保持无蠕虫状态。实验包括两个为期 5 天的周期，外加 5 天的适应期。在第一周期中，动物提供了五种植物物种的叶子，单宁含量逐渐降低（CT）（金合欢 bahamensis、 Gymnopodium floribundum、 Havardia albicans、 Acacia pennatula、 Lysiloma latisiliqum），以及三种单宁含量可忽略不计的植物物种（Leucaena leucocephala、Piscidia piscipula 和 Brosimum alicastrum）。在第二个周期中，撤回了 B. alicastrum 的叶子。每天以 DM 基础上 1% BW 的比例提供基于谷物的浓缩饲料。确定干物质和营养素的摄入量。使用 Chesson 选择指数确定每个实验组的叶子选择。每天两次测定感染山羊的粪便每克虫卵数（EPG）。Chesson 指数显示，在第 1 期和第 2 期，叶子选择具有相似的模式。IG 中山羊的平均 EPG 在第 1 期为 2028±259 EPG，在第 2 期为 1293±198 EPG（P>0.05）。在第 1 期，B. alicastrum（无单宁）的选择模式最高，其次是富含单宁的植物（M. bahamensis）。这两种植物在第 2 期仍然是高度选择的。Chesson 指数表明，两个实验组（IG 和 NIG）在两个时期都选择了相同的植物物种。因此，高旋毛虫感染不会影响富含 CT 的植物的山羊选择。显然，山羊通过选择的植物来平衡其营养摄入，表现出营养智慧的证据。这种平衡可能有助于防止饮食中过量的蛋白质，并维持低 GIN 感染，这两者都被认为是预防性自我治疗的例子。
