Abstract

The objective of this work was to develop total dry matter intake (TDMI) prediction models for growing cattle. The Finnish dataset of 1006 experimental period treatment means from 17 feeding trials in growing bulls was collected for developing TDMI prediction models. The diets were mainly based on grass silage or grass silage partly or completely replaced by whole-crop silages or straw. The concentrate feeds consisted mainly of cereal grains, fibrous by-products and various protein supplements. The following non-linear equation for the relationship between TDMI and body weight (BW) (kg) was defined: TDMI (kg/d)=0.191 x BW0.627 (Adj. RMSE=0.451). The model was improved when both the constant and exponent were adjusted for dietary variables. Dietary neutral detergent fibre (NDF) concentration (kg/kg DM) generated a greater improvement in the model than other variables investigated (dietary concentrations of forage NDF and ME, and the proportion of concentrate). The constant decreased and the exponent increased with increasing dietary NDF concentration. The following equation was defined: TDMI (kg/d)=(0.209-0.489 x NDF) x BW ((0.614+0397 x NDF)) (Adj. RMSE=0.438). In the model NDF concentration was centred to the mean concentration of 0.40 kg/kg DM. The model was marginally improved when the constant was adjusted for silage DMI (SDMI)-index that was centred to 100 units and dietary concentration of volatile fatty acids (VFA). The effects of SDMI-index and VFA were highly significant (P<0.01): TDMI (kg/d)= (0.199-0.380 x NDF+0.000348 x SDMI-index - 0.00044 x VFA) x BW(0.624 + 0348 x NDF) (Adj. RMSE=0.433). A complete dataset was used for the evaluation of models developed from the Finnish dataset. The complete dataset was collected from growing cattle feeding experiments, in which total mixed rations or forages were fed ad libitum. Overall, the complete dataset comprised 135 feeding experiments and 687 treatment means. The following relationship between observed and predicted TDMI was derived with a non-linear model including SDMI-index and dietary VFA concentration as adjustment factors for the constant: Observed TDMI=-0.35(+/- 0.40)+1.01 (+/- 0.051) x Predicted TOMI (n=421; Adj. RMSE=0.243). The developed models can be used to estimate the intake responses to BW and diet changes. They provide an improved basis for practical ration formulation systems and economic evaluation. (C) 2013 Elsevier B.V. All rights reserved.

Keywords

Intake; Growing cattle; Modelling; Diet factors; Animal factors

Published in

Livestock Science
2013, Volume: 158, number: 1-3, pages: 74-83
Publisher: ELSEVIER SCIENCE BV

SLU Authors

• Huhtanen, Pekka

  • Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Animal and Dairy Science


Publication identifier

DOI: https://doi.org/10.1016/j.livsci.2013.10.005

Permanent link to this page (URI)

https://res.slu.se/id/publ/52652