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* Teagasc Moorepark Dairy Production Research Centre, Fermoy, Co. Cork, Ireland
School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
Teagasc, Kildalton College, Piltown, Co. Kilkenny, Ireland
1 Corresponding author. john.murphy{at}teagasc.ie
Fifty-six autumn-calving Holstein-Friesian cows, blocked on the basis of days in milk (27.6 ± 10.65 d), lactation number (3.1 ± 2.21), and preexperimental milk yield (28.4 ± 6.69 kg) were used to examine the effects of replacing 330 g/kg of dry matter (DM) of first-cut perennial ryegrass silage with either fermented whole-crop wheat (WCW), urea-treated processed WCW, or corn silage on subsequent feed intake, milk production, and efficiency of nitrogen utilization. The DM (g/kg), crude protein (CP, g/kg of DM) and in vitro DM digestibility (g/kg) of the forages were 204, 179, and 762 for grass silage; 389, 90, and 711 for fermented WCW; 795, 141, and 768 for urea-treated processed WCW; and 346, 93, and 783 for corn silage, respectively. Four forage treatments were evaluated as follows: 1) grass silage as the sole forage (GS); 2) a mixture of grass silage and fermented WCW silage, (F-WCW); 3) a mixture of grass silage and urea-treated processed WCW, (UP-WCW); and 4) a mixture of grass silage and corn silage (CS). In all cases, the alternative forages comprised 67% of the forage mix on a DM basis. Isonitrogenous diets were formulated by offering all cows 8 kg of concentrate as fed, formulated to different CP concentrations. Cows were offered these diets from 28 to 104 d in milk. Total DM intake and milk yield were greater on UP-WCW (20.0 and 30.2 kg/d) and CS (18.3 and 33.2 kg/d) than on GS (13.5 and 26.5 kg/d). Although DM intake was greater on F-WCW (17.1 kg/d) than on GS, milk yield was not significantly greater (+2.7 kg/d). Milk protein concentration was greater on F-WCW (30.5 g/kg), UP-WCW (31.3 g/kg), and CS (30.7 g/kg) than on GS (28.5 g/kg). However, there was no difference between treatments in milk fat or lactose concentrations. Body weight change was greater for cows offered GS (–0.27 kg/d) than for those offered UP-WCW (–0.01 kg/d) and CS (+0.05 kg/d) but not compared with those offered F-WCW (–0.06 kg/d). There was no effect of treatment on plasma glucose, nonesterified fatty acids, ß-hydroxybutyrate, urea, or total protein at d 64 ± 17.4 and d 92 ± 17.4 postpartum. Efficiency of N utilization was greatest for CS with 0.36 of N intake being recovered in milk compared with 0.28, 0.32, and 0.26 for GS, F-WCW, and UP-WCW, respectively. There was no effect of treatment on milk urea N concentration or the urinary allantoin N to creatinine N ratio. The results of this experiment indicate that corn silage is a more suitable supplementary forage to grass silage than fermented or urea-treated processed WCW, with advantages realized in milk production and more efficient N utilization.
Key Words: alternative forage • dairy cow • milk production • nitrogen utilization
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  K. M. Cooke, J. K. Bernard, and J. W. West Performance of Dairy Cows Fed Annual Ryegrass Silage and Corn Silage with Steam-Flaked or Ground Corn J Dairy Sci, June 1, 2008; 91(6): 2417 - 2422. [Abstract] [Full Text] [PDF]
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