title: Intake and digestibility in cattle fed low-quality tropical forage and supplemented with nitrogenous compounds.
abstract: The effects of supplementation with nitrogenous compounds on intake, digestibility, and microbial protein synthesis in cattle fed low-quality tropical forage were assessed. Five rumen fistulated crossbred Holstein x Gir heifers were used, with initial average live weight of 180 +/- 21 kg. Signal grass (Brachiaria decumbens) hay (48.6 g kg(-1) of crude protein (CP), on a dry matter (DM) basis) was used as roughage. Five treatments were defined according to nitrogen supplementation level (0, 20, 40, 60, and 80 g of CP kg(-1) above the CP level of the hay). A mixture of urea, ammonium sulfate, and albumin at the ratios of 4.5:0.5:1.0, respectively, was used as nitrogen source. The experiment consisted of five experimental periods, according to a 5 x 5 Latin square design. The average CP contents in the diets were 51.9, 71.1, 86.0, 116.7, and 130.2 g kg(-1), on a DM basis. A quadratic effect was detected (P < 0.10) of the CP levels in the diets on DM and neutral detergent fiber intake (kg/day), with maximum response at the levels of 102.4 and 100.5 g CP kg(-1) DM, respectively. The average daily concentration of rumen ammonia nitrogen showed increasing linear pattern (P < 0.01) as function of CP levels in the diet, with estimated value of 9.64 mg dL(-1) equivalent to the maximum DM intake. Microbial nitrogen flow in the intestine was linearly and positively related (P < 0.01) with the CP levels in the diet.
authors.affiliation: Departamento de Zootecnia, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
authors.forename: Claudia B
authors.initials: CB
authors.lastname: Sampaio
authors.forename: Edenio
authors.initials: E
authors.lastname: Detmann
authors.forename: Mario F
authors.initials: MF
authors.lastname: Paulino
authors.forename: Sebastiao C
authors.initials: SC
authors.lastname: Valadares Filho
authors.forename: Marjorrie A
authors.initials: MA
authors.lastname: de Souza
authors.forename: Isis
authors.initials: I
authors.lastname: Lazzarini
authors.forename: Pedro V Rodrigues
authors.initials: PV
authors.lastname: Paulino
authors.forename: Augusto C
authors.initials: AC
authors.lastname: de Queiroz
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology; D000818:Animals; D035201:Brachiaria; D001938:Brazil; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D004044:Dietary Proteins / Q000378:metabolism; D019587:Dietary Supplements; D004063:Digestion / Q000502:physiology; D004435:Eating / Q000502:physiology*; D005260:Female; D017672:Nitrogen Compounds / Q000494:pharmacology*; D014329:Tropical Climate
chemical_list: D004044:Dietary Proteins; D017672:Nitrogen Compounds