239 Effect of carbohydrate source on dry matter intake and digestibility, and nutritional status of ewes milked year-round on an accelerated lambing system

The effect of level of soyhull inclusion on dry matter intake, feed efficiency, apparent dry matter digestibility, in-vitro NDF appearance and body weight changes was investigated in this triply replicated, 3′3 Latin square design. Finnsheep ′ Dorset ewes (n = 53) were managed in 3 management groups. Ewes in each management group were housed in 3 pens, lactated 3 times in the 22-month experiment, and were fed a different experimental diet in each lactation. Diets L-SH, M-SH, and H-SH contained 34.4, 42.4, and 50.9% soyhulls and measured 31.9, 36.5, and 40.0 ± 0.60% NDF (P < 0.001), and 41.1, 37.1, and 32.8 ± 0.58% NFC (P < 0.001), respectively. Individual equations were fitted to each of the 27 pens, and the resulting data were analyzed with a model including Square Number, Pen and Lactation within Square Number, and Diet, with 3 to 6 ewes in each cell of each Latin Square. Dry matter intake was 2.54, 2.70, and 2.67 ± 0.05 kg per day, feed efficiency was 0.56, 0.60, and 0.54 ± 0.02 kg milk/kg DM per day and weight gains were 131.0, 144.0, and 138.0 ± 0.04 g per day for ewes consuming the L-SH, M-SH, and H-SH diets, respectively, with no significant differences among diets. Fermentable NDF in the diets increased linearly with soyhull inclusion (17.6, 21.1, and 24.3 ± 1.28%, P < 0.001). Apparent DM digestibility, measured with acid insoluble ash as marker, decreased nonsignificantly with soyhull inclusion (66.3, 64.5, and 63.9 ± 1.57%). The rate of in vitro NDF digestion decreased linearly with soyhull inclusion (166, 150, and 125 ± 5.7 g per hour, P < 0.01) for the L-SH, M-SH, and H-SH diet, respectively. In this experiment the M-SH diet resulted in the most favorable results of highest dry matter intake, milk yields, and feed efficiencies.