Selectivity and feeding behavior of Saanen goats subjected to three nutritional levels

ABSTRACT This study was conducted to investigate the effect of selective feeding habits on the quality of the ingested diet and the effect of feed restriction on the selectivity and behavior of goats in feedlots. Differences were found only in the amount of feed given to the animals, with a difference in the amount of feed rejected as a function of the nutritional level. Higher levels of orts were measured for those animals that received the ad libitum diet. For the composition of orts, differences were measured only in the ether extract fraction. Animals fed the ad libitum diet increased their intake of ether extract and energy, crude fiber, neutral detergent fiber, and acid detergent fiber. Thus, they had a preference for consuming the fibrous and energetic portions of the diet to the detriment of the mineral matter. The granulometry influenced the leftovers for the male and female treatments only in the diet that contained the 2.00- and 0.063-mm sized particles, with larger leftovers for the females. There were statistical differences as a function of feeding level for time spent in rumination, with stereotypical behavior, and in time spent standing up or lying down. As a function of sex, the differences were the same variables, including the time spent with agonistic behavior. Animals that received the ad libitum diet had a greater gain and final weight, whereas the animals that received the 60% restricted diet had the lowest performance, as did the females. Feed restriction changed the natural feeding behavior of goats, with smaller feed particles preferred. The feed restriction and sex also influenced the time spent on nonproductive activities, and the animals became more restless, with females having a higher social behavior than males.

摘要：本研究旨在探究选择性采食习性（selective feeding habits）对采食日粮品质的影响，以及限饲（feed restriction）对圈养山羊（goats in feedlots）采食选择性与行为的影响。研究仅在动物的饲喂投喂量上存在差异，且残饲（orts）量随营养水平不同而有所变化；采食自由采食日粮（ad libitum diet）的山羊，其残饲量更高。在残饲的组分上，仅在乙醚提取物组分（ether extract fraction）中存在差异，采食自由采食日粮的山羊，其乙醚提取物、能量、粗纤维（crude fiber）、中性洗涤纤维（neutral detergent fiber）及酸性洗涤纤维（acid detergent fiber）的采食量均有所提升，由此可见山羊更偏好采食日粮中的纤维与能量组分，而减少对矿物质的摄入。颗粒粒度（granulometry）仅对含2.00mm和0.063mm粒径颗粒的日粮的残饲量存在影响，且母山羊的残饲量更高。饲喂水平对反刍（rumination）时长、刻板行为（stereotypical behavior）时长以及站立或躺卧时长存在显著统计学差异；按性别划分时，除上述变量外，攻击行为（agonistic behavior）时长也存在差异。采食自由采食日粮的山羊增重（gain）与末重（final weight）均更高，而饲喂60%限饲日粮的山羊生产性能最低，母山羊亦是如此。限饲改变了山羊的自然采食行为，山羊更偏好粒径更小的饲料；限饲与性别同样会影响山羊的非生产性活动（nonproductive activities）时长，山羊会变得更为躁动，且母山羊的社交行为（social behavior）频次高于公山羊。