Effect of supplementing napier grass (Pennisetum purpureum) with sunflower meal or poultry litter-based concentrates on feed intake, live-weight changes and economics of milk production in Friesian cows
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A study was conducted using a randomized complete block design to determine feed intake, live-weight changes, milk yield and cost of milk production in Friesian cows fed napier grass (NG) at 10 weeks (MNG) or 15 weeks (ONG) of maturity. The MNG or ONG was supplemented with equal amounts of sunflower (SFBC) or poultry litter (PLBC) based concentrates in experiment 1, while in experiment 2, the MNG was supplemented with graded levels of the PLBC. In experiment 1, the intakes of total organic matter (TOMI) was lower (135.9 vs. 137.7 g kg W0.75) while intake of total crude protein (TCPI) was greater (16.6 vs. 12.0 g kg W0.75) for MNG than ONG diets (P<0.001). The TOMI (137.8 vs. 135.8 W0.75) and TCPI (14.3 vs. 14.2 W0.75) were higher for SFBC than PLBC diets (P<0.05). The yield of milk corrected for butter fat (FCM) was higher (11.0 vs. 5.7 kg cow−1 day−1) for MNG than ONG diets (P<0.001). In experiment 2, the TOMI (112.8 vs. 130.6 g kg W0.75) and the TCPI (12.2 vs. 16.1 g kg W0.75) were lower for MNG only diet than the mean of the supplemented MNG (P<0.001). The MNG only diet supported lower yields of FCM (7.7 vs. 10.7 kg cow−1 day−1) than the mean of the supplemented MNG (P<0.001). Although supplemented cows fed MNG diets gained weight, those fed supplemented ONG diets or MNG only diet lost weight. Feeding of supplemented ONG resulted in loss of revenue while supplementing with PLBC had higher profits than SFBC. We concluded that use of the PLBC would lower costs and improve milk production in dairy cows fed NG-based diets.