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Nutrição Animal • Rev. bras. saúde prod. anim. 18 (1) • Mar 2017 • https://doi.org/10.1590/S1519-99402017000100008   copy

Evaluation of equations for estimating the consumption of dairy cows

Authorship SCIMAGO INSTITUTIONS RANKINGS

SUMMARY

The present study aimed to perform a comparison of the predictive power of different equations to estimate intake by dairy cows. The work was conducted through collecting information in literature about body weight, milk yield, days in milk, dry matter intake and fat content of milk of dairy cows raised in Brazil. All this information, with the exception of dry matter intake, were used to predict the dry matter intake with equations of the model: National Research Council (NRC, 2001NATIONAL RESEARCH COUNCIL - NRC. Nutrient requeriments of dairy cattle. 7. ed. Washington: National Academy Press, 2001.), Cornell Net Protein and Carbohydrate System (CNCPS, 2004), Agricultural and Food Research Council (AFRC, 1993AGRICULTURAL AND FOOD REASERCH COUNCIL. Energy and protein requirements of ruminants. Oxon: CAB international, 159 p.1993.) and De Freitas et al. (2006)DE FREITAS, A.J.; LANA, P.R.; RODRIGUEZ, M.L.A.; SOUZA, J.C. Predição e validação do desempenho de vacas de leite nas condições brasileiras. Arquivo Latino Americano de Produção Animal, v.14, p.120-134, 2006.. Subsequently, the predictive power of the mathematical equations was compared through the graphical comparison of the standard as Draper and Smith (1966)DRAPER, N.R.; SMITH, H. Applied regression analysis. New York: John Wiley & Sons, 1966. p.407. and Montgomery (2005)MONTGOMERY, C.D. Design and analysis of experiments. 6.ed. Nova Iorque. John Wiley & Sons, 2005. 643 p. and by means of Akaike's criterion (Akaike, 1974AKAIKE, H. A new look at the statistical model identification. IEEE Transactions on Automatic Control, v.19, n.6, p.716-23.1974.) waste. NRC (2001)NATIONAL RESEARCH COUNCIL - NRC. Nutrient requeriments of dairy cattle. 7. ed. Washington: National Academy Press, 2001. was the best choice for presenting the ERr = 1, all others showed ERr much greater than 20 and therefore must be considered worse choices. AFRC (1993)AGRICULTURAL AND FOOD REASERCH COUNCIL. Energy and protein requirements of ruminants. Oxon: CAB international, 159 p.1993. has tended to underestimate the predicted values with 76% points above the line of invalidity. Model NRC (2001)NATIONAL RESEARCH COUNCIL - NRC. Nutrient requeriments of dairy cattle. 7. ed. Washington: National Academy Press, 2001. is the one that best predicts the dry matter intake of dairy cows under the conditions studied.

Key words:
dairy cattle; intake prediction; diet formulation; ruminant nutrition

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