Gradual weaning does not improve performance for calves with low starter intake at the beginning of the weaning process.

Autor:	Bittar CMM; Department of Animal Science, University of Sao Paulo, Piracicaba, SP 13418900 Brazil. Electronic address: carlabittar@usp.br., Gallo MP; Department of Animal Science, University of Sao Paulo, Piracicaba, SP 13418900 Brazil., Silva JT; Department of Animal Science, University of Sao Paulo, Piracicaba, SP 13418900 Brazil., de Paula MR; Department of Animal Science, University of Sao Paulo, Piracicaba, SP 13418900 Brazil., Poczynek M; Department of Animal Science, University of Sao Paulo, Piracicaba, SP 13418900 Brazil., Mourão GB; Department of Animal Science, University of Sao Paulo, Piracicaba, SP 13418900 Brazil.
Jazyk:	angličtina
Zdroj:	Journal of dairy science [J Dairy Sci] 2020 May; Vol. 103 (5), pp. 4672-4680. Date of Electronic Publication: 2020 Mar 12.
DOI:	10.3168/jds.2019-17614
Abstrakt:	The weaning process may cause intense stress for dairy calves, even when low volumes of liquid diet are fed. Management tools that increase the intake of solid feeds, such as gradual weaning, can provide better physiological and metabolic conditions through better ruminal development, leading to better adaptation to ruminant metabolism and aiding in stress mitigation. The objective of this study was to evaluate the effects of 2 weaning protocols and 2 levels of concentrate intake on the performance and physiological and behavioral variables related to stress in dairy calves. Thirty-six newborn male Holstein calves were used in a randomized block design with a 2 × 2 factorial arrangement: 2 weaning strategies, abrupt or gradual, and 2 levels of concentrate intake at 5 wk of age, high (>350 g/d) or low (≤350 g/d). Calves were equally managed until they were 5 wk of age and then grouped according to concentrate intake. Statistical analyzes were performed using the MIXED procedure of SAS software (SAS Institute Inc., Cary, NC), and no significant interaction was observed between studied factors (weaning method and starter intake level); therefore, we considered each factor separately and their interactions with age. The highest dry matter intake and concentration of β-hydroxybutyrate were recorded for animals with a high level of starter intake independent of the weaning method. Structural growth (cm/wk) and average daily gain were superior for calves with high starter intake, but weaning method had no effect. The gradual weaning protocol increased the time eating starter, regardless of the level of concentrate intake. Even animals with low concentrate intake that were weaned abruptly showed levels of cortisol and acid-soluble glycoprotein within normal physiological levels. Apparently, other factors besides the milk supply affect the starter intake level of calves in a conventional feeding program. The adoption of gradual weaning is not effective in improving performance when a calf has low intake 3 wk before weaning is complete, but it reduced vocalization on d 2 postweaning. (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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