Intake pattern and nutrient supply of lactating sheep selecting dried forage from woody plants and straw offered in binary or multiple choice
This study investigated whether offering either binary or multiple choice among low quality forages has an effect on intake and feeding behaviour compared to no-choice situations where only one single low-quality forage is offered. Forages from different woody plants and straw were tested in lactating sheep either in Syria (Exp. 1; Awassi sheep) or in Switzerland (Exp. 2; East Friesian Dairy sheep). Artemisia herba-alba, Atriplex leucoclada, Haloxylon articulatum, Noaea mucronata, and Salsola vermiculata were used in Exp. 1. The three most preferred plants (A. leucoclada, H. articulatum and S. vermiculata) were tested again in Exp. 2 together with Betula pendula, Castanea sativa and Juglans regia. Both experiments started with a binary choice test where one plant and barley straw were offered separately for 4 h in the morning to six sheep (test period) in a random sequence in consecutive 7-day subperiods. A control group (n = 6 per experiment) received only straw in the test period. For the rest of the day, a basal diet composed of straw ad libitum and concentrate was offered. After the binary choice test, two 2-week periods followed, where in the first straw only and in the second all test plants were offered to all animals from both groups to ascertain equal familiarisation with all plants. For the following 7-day multiple choice test animals were allocated to two new groups. The multiple choice group could choose among all test plants and straw during the 4-h test period, the control group received only the basal diet. Intakes of test feeds during 4 h and 24 h as well as feeding behaviour during the first 30 min were recorded. Additionally, nutrient intake was determined. Total daily test feed intake was always higher in the choice groups, but this was more pronounced in the multiple choice situation (Exp. 1: 30 and 48, Exp. 2: 49 and 74 g dry matter/kg live-weight0.75 with control and multiple choice, respectively). A. leucoclada (Exp. 1; proportionately 0.73 of total test plant intake) and B. pendula (Exp. 2; 0.87) were the preferred plants in the multiple choice test and also with binary choice. Most other feeds were only consumed in low amounts in the binary and even less in multiple choice situations. In conclusion, giving sheep the choice among low quality forages seemed to be advantageous. Even though in both experiments animals preferred especially one plant, choice still facilitated intake.