title: Feed efficiency, blood parameters, and ingestive behavior of young Nellore males and females.
abstract: This study aimed to evaluate differences in efficiency of feed utilization between young Nellore males and females by comparing growth traits, feed intake, blood parameters, and ingestive behavior of the animals. Data from 768 Nellore males and females that participated in eight performance tests for individual feed intake evaluation were used. Performance and feed efficiency measures, efficiency-related hematological, metabolic and hormonal variables, and data regarding ingestive behavior were collected. Feed efficiency measures were defined by the relationship between performance and feed intake. Data were analyzed using mixed models that included the fixed effects of sex, herd, and the covariate age within sex and the random effects of facility within year, year, and residual. Significant differences between males and females were observed for traits related to weight gain and feed intake. Although individual dynamics of feed efficiency measures differed between males and females, no significant differences in residual feed intake, feed efficiency, or relative growth rate were observed between sexes. Significant differences between sexes were found for platelets, red blood cells, hemoglobin, creatinine, glucose, urea, triglycerides, insulin, cortisol, and IGF-I. Females spent more time feeding and less time ruminating when compared to males. However, males exhibited higher feeding efficiency and lower rumination efficiency than females. Growing Nellore males and females are efficient in feed utilization, and the differences in blood variables observed are probably due to differences in body size and feed intake. Males spend less time eating, consume more food, and spend more time ruminating than females.
authors.affiliation: Instituto de Zootecnia, Centro APTA Bovinos de Corte, Rodovia Carlos Tonani, km 94. Caixa Postal 63, CEP14.160-970, Sertãozinho, SP, Brazil. sbonilha@iz.sp.gov.br.
authors.forename: Sarah Figueiredo Martins
authors.initials: SF
authors.lastname: Bonilha
authors.affiliation: Instituto de Zootecnia, Centro APTA Bovinos de Corte, Rodovia Carlos Tonani, km 94. Caixa Postal 63, CEP14.160-970, Sertãozinho, SP, Brazil.
authors.forename: Joslaine Noely dos Santos Gonçalves
authors.initials: JN
authors.lastname: Cyrillo
authors.affiliation: Instituto de Zootecnia, Centro APTA Bovinos de Corte, Rodovia Carlos Tonani, km 94. Caixa Postal 63, CEP14.160-970, Sertãozinho, SP, Brazil.
authors.forename: Guilherme Pinheiro
authors.initials: GP
authors.lastname: dos Santos
authors.affiliation: Instituto de Zootecnia, Centro APTA Bovinos de Corte, Rodovia Carlos Tonani, km 94. Caixa Postal 63, CEP14.160-970, Sertãozinho, SP, Brazil.
authors.forename: Renata Helena
authors.initials: RH
authors.lastname: Branco
authors.affiliation: Instituto de Zootecnia, Centro APTA Bovinos de Corte, Rodovia Carlos Tonani, km 94. Caixa Postal 63, CEP14.160-970, Sertãozinho, SP, Brazil.
authors.forename: Enilson Geraldo
authors.initials: EG
authors.lastname: Ribeiro
authors.affiliation: Instituto de Zootecnia, Centro APTA Bovinos de Corte, Rodovia Carlos Tonani, km 94. Caixa Postal 63, CEP14.160-970, Sertãozinho, SP, Brazil.
authors.forename: Maria Eugênia Zerlotti
authors.initials: ME
authors.lastname: Mercadante
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001938:Brazil; D002417:Cattle / Q000097:blood / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D005247:Feeding Behavior; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male
chemical_list: D007328:Insulin; D007334:Insulin-Like Growth Factor I; D006854:Hydrocortisone
keywords: Beef cattle; Feed utilization; Metabolism; Sex class