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Oscillating and static dietary crude protein supply. I. Impacts on intake, digestibility, performance, and nitrogen balance in young Nellore bulls.
Menezes, Ana Clara B; Valadares Filho, Sebastião C; Pacheco, Marcos V C; Pucetti, Pauliane; Silva, Breno C; Zanetti, Diego; Paulino, Mário F; Silva, Fabyano F; Neville, Tammi L; Caton, Joel S.
Afiliação
  • Menezes ACB; Department of Animal Science, Universidade Federal de Viçosa, , Viçosa, Minas Gerais, Brazil.
  • Valadares Filho SC; Department of Animal Science, Universidade Federal de Viçosa, , Viçosa, Minas Gerais, Brazil.
  • Pacheco MVC; Department of Animal Science, Universidade Federal de Viçosa, , Viçosa, Minas Gerais, Brazil.
  • Pucetti P; Department of Animal Science, Universidade Federal de Viçosa, , Viçosa, Minas Gerais, Brazil.
  • Silva BC; Department of Animal Science, Universidade Federal de Viçosa, , Viçosa, Minas Gerais, Brazil.
  • Zanetti D; Federal Institute of Education, Science and Technology of Southern Minas Gerais, Machado, Minas Gerais, Brazil.
  • Paulino MF; Department of Animal Science, Universidade Federal de Viçosa, , Viçosa, Minas Gerais, Brazil.
  • Silva FF; Department of Animal Science, Universidade Federal de Viçosa, , Viçosa, Minas Gerais, Brazil.
  • Neville TL; Department of Animal Science, Universidade Federal de Viçosa, , Viçosa, Minas Gerais, Brazil.
  • Caton JS; Department of Animal Sciences, North Dakota State University, Fargo.
Transl Anim Sci ; 3(4): 1205-1215, 2019 Jul.
Article em En | MEDLINE | ID: mdl-32704884
Effects of dietary crude protein (CP) supply on intake, digestibility, performance, and N balance were evaluated in young Nellore bulls consuming static or oscillating CP concentrations. Forty-two young bulls (initial BW of 260 ± 8.1 kg; age of 7 ± 1.0 mo) were fed ad libitum and were randomly assigned to receive one of six diets with different CP concentrations for 140 d: 105 (LO), 125 (MD), or 145 g CP /kg DM (HI), and LO to HI (LH), LO to MD (LM), or MD to HI (MH) oscillating CP at a 48-h interval for each feed. At the end of the experiment, bulls were slaughtered to evaluate carcass characteristics. Linear and quadratic effects were used to compare LO, MD, and HI, and specific contrasts were applied to compare oscillating dietary CP treatments vs. MD (125 g CP/kg DM) static treatment. Dry matter intake (DMI) was not affected (P > 0.26) by increasing or oscillating dietary CP. As dietary N concentration increased, there was a subsequent increase in apparent N compounds digestibility (P = 0.02), and no significant difference (P = 0.38) was observed between oscillating LH and MD. Daily total urinary and fecal N increased (P < 0.01) in response to increasing dietary CP. Significant differences were observed between oscillating LM and MH vs. MD, where bulls receiving the LM diet excreted less (P < 0.01; 71.21 g/d) and bulls fed MH excreted more (P < 0.01) urinary N (90.70 g/d) than those fed MD (85.52 g/d). A quadratic effect was observed (P < 0.01) for retained N as a percentage of N intake, where the bulls fed LO had greater N retention than those fed HI, 16.20% and 13.78%, respectively. Both LH and LM had greater (P < 0.01) daily retained N when compared with MD. Performance and carcass characteristics were not affected (P > 0.05) by increasing or oscillating dietary CP. Therefore, these data indicate that although there is no alteration in the performance of growing Nellore bulls fed with oscillating CP diets vs. a static level of 125 g CP/kg DM, nor static low (105 g CP/kg DM) and high (145 g CP/kg DM) levels; there may be undesirable increases in environmental N excretion when the average dietary CP content is increased. The results suggest that dietary CP concentrations of 105, 125 g/kg DM, or within this range can be indicated for finishing young Nellore bulls, since it reaches the requirements, reduces the environmental footprint related to N excretion, and may save on costs of high-priced protein feeds.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: Transl Anim Sci Ano de publicação: 2019 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: Transl Anim Sci Ano de publicação: 2019 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido