title: Effect of supplementation with urea, blood meal, and rumen-protected methionine on growth performance of Holstein heifers grazing kikuyu pasture.
abstract: Supplements with corn grain, molasses cane, and different nitrogen sources were evaluated in 16 growing Hosltein heifers [227 ± 33 kg body weight (BW)] grazing kikuyu (Pennisetum clandestinum) pasture in a 10-ha sward (rotational grazing with electric fences) during 90 days in the summer season. The nitrogen sources were urea (U); urea and blood meal (U+BM); and urea, blood meal, and rumen-protected methionine (U+BM +RPM). Heifers were randomly assigned to four experimental supplements defined as follows: control (no supplementation), U, U+BM, and U+BM +RPM. Two kilograms (as fed) of supplement was offered daily. The final BW of heifers fed U+BM +RPM was higher (P<0.05) than heifers not supplemented. The total and average daily weight gain of heifers supplemented with U+BM +RPM were higher than heifers not supplemented or supplemented with U and U+BM (P<0.05). The average daily gain of heifers supplemented with U and U+BM were higher than heifers not supplemented (P<0.05). Grass intake was not affected by supplementation, but total dry matter intake was increased by supplements with U, U+BM, and U+BM +RPM (P<0.05). Feed conversion was improved by U+BM +RPM (P<0.05). Total tract digestion was not affected by supplements. Blood urea nitrogen concentrations of heifers supplemented with U, U+BM, and U+BM +RPM were higher than heifers not supplemented (P<0.05). It is concluded that supplements with U+BM +RPM improved growth performance and feed conversion in heifers grazing kikuyu pasture.
authors.affiliation: División Académica de Ciencias Agropecuarias, Universidad Juárez Autónoma de Tabasco, km 25 Villahermosa-Teapa, Villahermosa, Tabasco, Mexico.
authors.forename: Armando
authors.initials: A
authors.lastname: Gomez
authors.forename: German David
authors.initials: GD
authors.lastname: Mendoza
authors.forename: Carlos
authors.initials: C
authors.lastname: Garcìa-Bojalil
authors.forename: Ricardo
authors.initials: R
authors.lastname: Barcena
authors.forename: Jesus A
authors.initials: JA
authors.lastname: Ramos
authors.forename: Maria M
authors.initials: MM
authors.lastname: Crosby
authors.forename: Juan M
authors.initials: JM
authors.lastname: Pinos-Rodríguez
authors.forename: Alejandro
authors.initials: A
authors.lastname: Lara
mesh_terms: D000821:Animal Feed; D000818:Animals; D001769:Blood; D001835:Body Weight / Q000502:physiology; D002417:Cattle / Q000254:growth & development* / Q000378:metabolism; D005260:Female; D008715:Methionine / Q000008:administration & dosage*; D011897:Random Allocation; D014508:Urea / Q000008:administration & dosage*
chemical_list: D014508:Urea; D008715:Methionine