The latest edition of the National Research Council’s Dairy Cattle Nutrition Manual features many updates and improvements, including a completely new computer program. The updated information enables users to pinpoint nutrient requirements for individual animals. The new edition also contains guidance on nutrient analysis of feed ingredients and formulation of diets for minimum environmental impact.
Equation based on animal factors predicts feed intake response by lactating cows to factors related to the filling effect of rations
To assess the predictive ability of an equation based on animal factors for the lactating cows’ feed intake response to ration filling effects, we compared it to an earlier published model, the Equation based on Animal Factors for Lactating Cows. The proposed equation showed a better fit to the data. It had lower RMSE and CCC values and a slope that was closer to unity. Both equations showed a similar mean bias, which showed that the proposed equation tended to over-predict the DMI for high DMI cows and under-predict the response of the same cows to low DMI.
The equation was valid when it was applied to single forage rations. The data for the other forages did not change significantly within the study. This means that the DMI derived from multiple forages should be analyzed using the weighted average of FNDFD values. Alternatively, a single data set’s mean FNDFD can be used in place of individual values. However, the data must be compared using the same retention time and method, and the laboratory standard must be the same for all forages.
The filling factors equation includes two possible factors: forage NDF content and ADF/NDF ratio. Both of these factors affect DMI in different ways. The higher the ratio of NDF to ADF, the higher the milk yield.
Equation based on filling effect predicts feed intake response by lactating cows to factors related to acid-base balance
The current study has shown that an equation based on the filling effect can predict the feed intake response of lactating cows to factors relating to acid-base balance. However, further research and development are necessary to optimize the model. In a future study, this model will incorporate additional factors that affect urea content in milk. Further work will include determining the urea content of milk and milking frequency, which are important factors that affect urea content.
In this study, the DMI predicted by the Equation was lower than the observed DMI, and the PDMI was lower than the predicted value for many herds. In addition, the study included only data up to 280 days. Nevertheless, the predicted crude protein intake was 3.64 kg/d, which ranged from 3.09 to 4.39 kg/d.
The model’s accuracy depends on the parameters that were input into the model. These variables can include genotype, physiological state, parity, and body mass. Using the model, feed intake responses of lactating cows can be predicted for milk yield, milk composition, and body mass.
The model should also include the effects of parity, genetic potential, and lactation stage. This is because the model must account for the effects of these factors on milk production and acid-base balance.
Equation based on animal factors predicts feed intake response by lactating cows to factors related to acid-base balance
A development dataset was generated from the feed intake of 54 multi-parity Holstein dairy cows with a DIM of 170 days and a BW of 621 kg. The cows were chosen randomly among two experimental batches at the same dairy farm and were maintained under similar experimental conditions.
Seven DMI prediction equations were developed. Each of the equations was evaluated according to its accuracy and predictability. In addition, they were compared by mean square prediction error. The more robust equations had lower prediction errors and are less risky for practical use. They were also evaluated by the number of independent data files for which their accuracy was unsatisfactory.
Several studies have been conducted on the effect of amino acids in feed on the acid-base balance in lactating cows. One study by Getachew, G., and Robinson, P.H. evaluated the effect of by-products on milk production. Another study by Gill and Robinson, P.H., studied the amino acid pattern of milk and the timing of protein meal intake in milk.
The equation predicts feed intake response in lactating cows to factors related to the acid-base balance in dairy cows based on animal factors. This equation includes dry matter, milk, sodium, and the weekly mean minimum temperature. This temperature is generally 10 to 15 degrees lower than the average daytime temperature.
