Evaluation of the Cornell Net Carbohydrate and Protein System model on the prediction of dry matter intake and milk production of grazing crossbred cows

Abstract

-The Cornel Net Carbohydrate and Protein System model version 5.0 was assessed as for its prediction of dry matter intake and milk production of grazing lactating Holstein × Zebu cows. Eight lactating cows grazing elephant grass (Pennisetum purpureum, Schum., cv. Napier) were used in two experiments of 30 days each. The experimental design was of randomized blocks (subplots). Dry matter intake was estimated using the chromium oxide and in vitro dry matter digestibility techniques. The estimated dry matter intake was compared with the values predicted by the model. Extrusa samples of the elephant grass pasture were obtained from a cow with esophageal fistula during nine days in each experimental period.Carbohydrate and nitrogenous fractions were analyzed and the degradation rate of carbohydrate was estimated by the gas production technique. The inputs referring to the animals (body weight, age, milk production, milk composition and breed type), to the environment (temperature, relative humidity of air and management condition) and to feeds chemical composition in each experimental period were inserted in the model. The model was accurate on the prediction of dry matter intake, considering that the mean values obtained by the chromium oxide technique and predicted by model (2.45 and 2.46% of body weight, respectively) did not differ significantly from each other. However, the model underestimated the observed milk production in 62.4%, where the metabolizable energy was the first limiting. These results demonstrate the need for studies that provide the development of a database for tropical foods (chemical composition and dynamics of rumen fermentation) and fitting of the model to the tropical conditions, for its appropriate application in formulation of diets and supplements in these regions.

Agronomic characteristics and nutritive value of elephant grass clones managed under rotational stocking during the dry period

“…These values were lower than those reported by Morenz et al (2012) with Napier grass managed under rotational stocking with a rest period of 30 days during the rainy season. Also, lignin contents varying from 5.1 to 7.6% were related to different elephantgrass cultivars (LIMA et al, 2008;VOLTOLINI et al, 2010;MORENZ et al, 2012). The results reported in the present study confirm the low lignin contents found by Madeiro (2010), who evaluated the same elephantgrass clones in the previous year.…”

Nutritional comparison between dried and ensiled indigofera, papaya and moringa leaves

“…However, this was not the case for indigofera in which it contained higher ADF than that of papaya but had gas production as well. It might be that other factors influencing gas production were present such as different types of carbohydrate, degradability and fermentability of carbohydrate under ruminal environment (Morenz et al, 2012) and antinutritive compounds (Laconi and Widiyastuti, 2010;Kondo et al, 2014), in which these parameters were not measured in the present experiment. Lower gas production after ensiling treatment apparently related to partial utilization of water soluble carbohydrate by lactic acid bacteria and other microorganims present in silage, thus contributing to a reduced gas production.…”