Prediction of nitrogen use in dairy cattle: a multivariate Bayesian approach

Abstract

Abstract. Quantification of dairy cattle nitrogen (N) excretion and secretion is necessary to improve the efficiency with which feed N is converted to milk N (ENU). Faecal and urinary N excretion and milk N secretion are correlated with each other and thus are more accurately described by a multivariate model that can accommodate the covariance between the three observations than by three separate univariate models. Further, by simultaneously predicting the three routes of excretion and taking advantage of the mass balance relationships between them, covariate effects on N partitioning from feed to faeces and absorbed N and from absorbed N to milk and urine N and animal ENU can be estimated. A database containing 1094 lactating dairy cow observations collated from indirect calorimetry experiments was used for model development. Dietary metabolisable energy content (ME, MJ/kg DM) increased ENU at a decreasing rate, increased the efficiency with which feed N was converted to absorbed N and decreased the efficiency with which absorbed N was converted to milk N. However, the parameter estimate of the effect of ME on post-absorption efficiency was not different from zero when the model was fitted to a data subset in which net energy and metabolisable protein were at or above requirement. This suggests the effect of ME on post-absorption N use is dependent on the energy status of the animal.

Modeling the trade-off between diet costs and methane emissions: A goal programming approach

“…Delivering protein and minerals above the requirement level potentially increases nitrogen and mineral excretion to the environment. For instance, protein overfeeding may increase nitrate run-off to the environment, contributing to eutrophication, and manure ammonia volatilization may cause respiratory problems in humans and animals as discussed by Reed et al (2014). At the same time, excess mineral consumption may alter electrolyte balance and negatively affect milk production and animal health.…”

Modeling the Effect of Nutritional Strategies for Dairy Cows on the Composition of Excreta Nitrogen

“…Such an evaluation requires a realistic and detailed representation of the cow's complex digestive processes. Several empirical models have been developed to predict output and composition of feces and urine (e.g., Reed et al, 2014;Appuhamy et al, 2018), but such models do not allow for detailed manure characterization and do not reflect the availability of N from urinary and fecal components for subsequent losses or use by plants.…”

Evaluation of Bayesian models for analysis of crude protein requirement for pigs of Brazilian Piau breed

“…Although Bayesian methods have been applied in different scientific fields, only recently these approaches could be used in animal nutrition studies Old et al, 2015;Rossi et al, 2016). Moreover, Bayesian models have been developed to address complex situations in livestock, such as dynamic nutrition (Reed et al, 2016) and nitrogen prediction experiments (Reed et al, 2014).…”