Partial substution of fine ground corn by peleted citrus pulp in the concentrate of lactating dairy cows, grazing intensive managed elephant-grass (Pennisetum purpureum, Shum).

Author(s)

Junio Cesar Martinez

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2004-06-21

Examining board members

Flavio Augusto Portela Santos; Fabio Prudencio de Campos; Wilson Roberto Soares Mattos

• Advisor: Flavio Augusto Portela Santos

Abstract

Two experiments were conducted to study the partial substitution of fine ground corn by peleted pulp citric in the concentrate of lactating cows in middle lactation (Experiment I) and in late lactation (Experiment II), grazing elephant - grass pasture. The trials were conducted at the Animal Science Department of ESALQ/USP. In both experiments, the animals were grouped according to milk yield, days in milk and parturition order. The statistical designs were repeated 4 x 4 Latin Square. The data were analysed using the Proc GLM of SAS (1999). Experiment I: Eight Holstein cows (82 DIM and 522.9 kg LBW), at the beginning of the trial were used. The concentrates contained the following corn:peleted citrus pulp proportions: 100:0 (T0); 75:25 (T25); 50:50 (T50); 25:75 (T75). The cows received 7 kg of concentrate day-1 (6.3 kg of DM), fractionated in 2 daily meals. The pasture was fertilized with 80 kg N ha.month-1. The forage offer was of 33,6 kg DM of green leaves cow day-1. There was not difference (P>0.05) in the grazing time (7h22’), rumination time (8h36’), leisure time (5h56’) and biting rate (34.4 movements min-1). The rectal temperature (38.74 and 39.64ºC) and respiratory frequency (47.44 and 61.20 movements min-1), measured at 8:00 AM and at 3:30 PM, respectively, were not affected by treatments (P>0.05). There was not difference (P>0.05) in 3.5 % FCM yield (18.5 kg cow day-1), in the contents of milk fat (3.5%), protein (3.06%), lactose (4.40%) and total solids (13.02%), milk urea-N (15.01 mg dL-1) and of somatic cells (203.000 mL-1) were not affected by treatments (P>0.05). The LBW (536.8 kg), BCS (2.51), plasma glucose (75.90 mg dL-1), plasma urea-N (16.96 mg dL-1) and plasma free fat acids (456.12 mEq L-1) were not affected by treatments (P>0.05). Experiment II: Eleven cows were used, 7 Holstein and 4 Jersey (427.5 kg LBW and 153.22 DIM), at the beginning of the trial. The concentrates were 21.8% of CP (DM bases), and the respective corn:peleted citric pulp ratio were: 100:0 (T0); 75:25 (T25); 50:50 (T50); 25:75 (T75). The cows were fed 6.1 kg day-1 of concentrate (5.5 kg of DM), fractionated in 2 daily meals, after each milking. There was not difference (P>0.05) in 3.5 FCM yield (13.7 kg cow day-1), in the content of milk fat (3.8%), protein (3.37%) and total solids (13.27%), milk urea-N (14.34 mg dL-1) and somatic cells (140,450 mL-1). The lactose content was lower (P<0.05) for the 25:75 diet. The LBW (427.2 kg), BCS (2.74), plasma glucose (74.63 mg dL-1), plasma urea-N (16.74 mg dL-1), and plasma free fat acids (417.81 mEq L-1) were not affected by treatments (P>0.05). There were no difference (P>0.05) in the grazing time (7h51’), rumination time (7h59’), leisure time (6h) and biting rate (37.91 movements min-1). The rectal temperature (38.76 and 39.61ºC) and respiratory frequency (53.57 and 71.50 movements min-1), measured at 8:00 and at 15:30 hours, respectively, were not affected by treatments (P>0.05). The corn can be substituted by the citric pulp without depreciating the milk yield and content. (AU)