title: Energy and protein requirements of young Holstein calves in tropical condition.
abstract: Our objective was to estimate the energy and protein requirements of Holstein young calves up to 87 days old. Forty-two Holstein calves aged 4 days were used. From these, ten were randomly selected and slaughtered to compose the baseline slaughter (BS) group. The remaining calves were randomly assigned to eight treatments in a 4 × 2 factorial using a completely randomized design. The treatments were 2, 4, 6, and 8 kg/day of milk (297 g/kg CP; 319 g/kg of fat) fed twice daily, and then harvested at 59 or 87 days of age. Calves were fed a starter (193 g/kg CP; 133 g/kg NDF) ad libitum in all treatments. The calves slaughtered at 87 days of age had milk replaced by Coast-cross (Cynodoon sp.) hay (125 g/kg CP; 728 g/kg NDF). The net requirement of energy for maintenance (NEm) was 0.36 MJ/kg EBWG, with efficiency of utilization of energy for maintenance (k m) of 59.4 %. The equation obtained to estimate the net requirement of energy for gain (NEg; MJ/d) was 4.40 × EBW(0.099), with the efficiency of utilization of energy for gain (k g) equal to 46.5 %. The observed requirements of net and metabolizable protein for maintenance (NPm and MPm) were 3.67 and 3.88 g/kg BW(0.75), respectively. The efficiency of use of metabolizable protein for maintenance (k pm ) was 94.6 %. The predicted requirements were higher than those observed in the literature, and this study demonstrated that the requirements of newborn calves are higher than the recommended.
authors.affiliation: Department of Animal Science, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.
authors.forename: João Paulo Pacheco
authors.initials: JP
authors.lastname: Rodrigues
authors.affiliation: Department of Animal Science, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.
authors.forename: Jessika Carolina Moutinho
authors.initials: JC
authors.lastname: Lima
authors.affiliation: Department of Animal Science, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.
authors.forename: Marcelo Messias Duarte
authors.initials: MM
authors.lastname: Castro
authors.affiliation: Department of Animal Science, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.
authors.forename: Sebastião de Campos Valadares
authors.initials: Sde C
authors.lastname: Filho
authors.affiliation: Embrapa, Brazilian Agricultural Research Corporation, 36038-330, Juiz de Fora, Minas Gerais, Brazil.
authors.forename: Mariana Magalhães
authors.initials: MM
authors.lastname: Campos
authors.affiliation: Department of Animal Science, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.
authors.forename: Mário Luiz
authors.initials: ML
authors.lastname: Chizzotti
authors.affiliation: Department of Animal Science, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil. marcosinaciomarcondes@gmail.com.
authors.forename: Marcos Inácio
authors.initials: MI
authors.lastname: Marcondes
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D001823:Body Composition; D001938:Brazil; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D004044:Dietary Proteins / Q000378:metabolism; D002149:Energy Intake; D008297:Male; D008892:Milk; D014329:Tropical Climate
chemical_list: D004044:Dietary Proteins
keywords: Comparative slaughter; Efficiency of utilization; Growth; Maintenance; Metabolizable energy; Metabolizable protein