MAIZE SILAGE SUPPLEMENTATION TO GRASS SILAGE INCREASES NITROGEN UTILISATION IN WETHER SHEEP

Cilj istraživanja bio je utvrditi utjecaj dodatka kukuruzne silaže (Zea mays L.) travnoj silaži različitih rokova košnje na iskoristivost dušika u hranidbi kastriranih ovnova. Travna silaža u kojoj je dominirala klupčasta oštrica (Dactylis glomerata L.) (80%) je spremljena u tri fenološke faze razvoja klupčaste oštrice; vlatanje, metličanje, cvatnja. Istraživanje je obuhvatilo 10 hranidbenih tretmana: travna silaža 1. roka košnje (TS1), travna silaža 2. roka košnje (TS2), travna silaža 3. roka košnje (TS3), kukuruzna silaža (KS), te hranidbene tretmane TS1, TS2 i TS3 u interakciji s KS (33, odnosno 67% u suhoj tvari (ST) obroka). Pokus je postavljen kao nepotpuni changeover plan s 10 kastriranih ovnova Charolais pasmine. Sadržaj ST u TS1, TS2 i TS3 je iznosio 396, 408 i 463 g kg-1 svježeg uzorka. S odgađanjem roka košnje travne mase za siliranje opadao je sadržaj sirovih proteina (SP) u TS2 u odnosu na TS1, te u TS3 u odnosu na TS2 (P<0,001), a rastao sadržaj neutralnih detergent vlakana (NDV) (P<0,05) i kiselih detergent vlakana (KDV) (P<0,001). KS je sadržavala 264 g ST kg-1 svježeg uzorka, 61,6 g SP kg-1 ST, te 211 g škroba kg-1 ST. Dodatak KS (33, odnosno 67%) travnim silažama (TS1, TS2 i TS3) je doveo do pozitivnog linearnog utjecaja (P<0,01) i pozitivnog združenog utjecaja (kvadratni, P<0,01) na konzumaciju N, te do pozitivnog združenog utjecaja (kvadratni, P<0,05) na iskoristivost N u hranidbi kastriranih ovnova.The objective of this experiment was to study the effects of maize silage (MS) supplementation (Zea mays L.) to grass silage (GS) harvested at three stages of maturity on nitrogen (N) utilisation in wether sheep. GS dominated by orchardgrass (Dactylis glomerata L.) (80%) was harvested at three maturity stages of orchardgrass: late vegetative (GS1), internode elongation (GS2) and flowering growth stage (GS3). The study consisted of ten feeding treatments incorporating GS1, GS2, GS3 and MS fed alone and forage mixtures of GS1, GS2, GS3 and MS (67 or 33% dry matter (DM) basis). DM concentrations in GS1, GS2 and GS3 were 396, 408 i 463 g kg-1 fresh sample, respectively. Delayed harvesting lowered (P<0.05) the crude protein (CP) concentration in GS2 compared to GS1 and in GS3 compared to GS2, while increased neutral detergent fibre (NDF) (P<0.05) and acid detergent fibre (ADF) concentration (P<0.001). The DM content (g kg-1fresh sample) and starch concentration (g kg-1 DM) of MS were 264 and 211, respectively. Inclusion of MS (33 or 67%) into grass silage based ration (GS1, GS2 and GS3) had positive linear (P<0.01) and positive associative effect (quadratic, P<0.01) on N intake as well as positive associative effect (quadratic, P< 0.05) on N utilisation in wether sheep