Preference study of four alternative silage fodders from the Mediterranean region in Murciano-Granadina goats

Abstract

In Mediterranean countries, large quantities of by-products are generated from artichoke and broccoli crops, as well as large masses of common reed due to the cleaning of riverbeds. They have traditionally been applied directly in animal feed, especially for small ruminants, without undergoing any preservation process. Their inclusion in diets would allow three benefits: feeding animals with materials containing high nutrient contents all year round (not only in the crop season) in a well-balanced ration, lowering the feeding costs and reducing the amount of residues and their elimination cost for producers. Through the silage process, these feedstuffs can be preserved to ensure year-round availability. The aim of this short-term preference trial was to evaluate the goats' preference among four different ensiled feedstuffs and to study the relationship between animal preference and the silage composition. The four alternative silage-feedstuffs were offered to four nulliparous Murciano-Granadina goats (34.9 ± 1.9 kg) in a multiple square or cafeteria design. The feedstuffs tested were artichoke bracts (Cynara scolymus), artichoke plant, a 50:50 mixture of broccoli by-product (Brassica oleracea, var. Italica) and artichoke bracts, and common reed (Phragmites australis). To determine preference, data were collected on feed intake and the time each animal spent eating each feedstuff for four hours each day. Macrocomposition and some functional and chemical characteristic silages were analysed. The relation between DM intake and chemical composition of the tested feedstuffs was determined using correlation and regression analyses. The artichoke bracts silage presented the highest cumulative intake at 4 h (3.26 g DM/kg BW); being different from artichoke plant silage (2.17 g DM/kg BW), the second most consumed. Broccoli + artichoke and common reed silage intake was significantly lower than those of the other two feeds (0.36 and 0.67 g DM/kg BW, respectively). The strongest correlations between DM intake after 4 h (g of DM) and the nutritional and chemical characteristics of the silages were found with digestible energy (r = 0.60, P < 0.001), lactic acid (r = 0.56, P < 0.001) and lignin (r = -0.54, P < 0.001). The relation was described by a best fit equation of the formula DM intake = -207.45 + 31.94 * lactic acid + 11.76 * CP (R2 = 0.48, P < 0.001). Goats showed a clear preference for ensiled artichoke bracts, followed by artichoke plant silage, with the broccoli + artichoke and common reed silages being less accepted. The feedstuff composition, especially lactic acid and crude protein contents, affects preference. Since no feedstuff was rejected in its entirety by animals and previous results ensured a good quality of these silages, the four feedstuffs had the potential for incorporation into goat diet, due to their nutritional characteristics