Improvement of a method to predict individual enteric methane emission of cows from milk MIR spectra

Besides being a greenhouse gas, enteric methane (CH produced by ruminants during rumination is also associated with the loss of 6 to 12% of gross energy intake. Mitigation of those emissions could be based on combined actions on diet, herd management and animal genetics. In order to investigate easily the relationship between these parameters and the CH4 emissions on a large scale, an equation to predict individual enteric CH4 emissions from the whole individual milk mid-infrared (MIR) spectra was developed. To build this equation a total of 452 CHA reference were obtained using the sF6 method. on Jersey, Holstein and Holstein-Jersey crossbred cows. In parallel a 40 ml sample of individual milk was collected at each milking (morning and evening) and was analyzed using MIR spectrometry Then, these spectra were averaged proportionally function of the milk production to have one spectrum for one CH4 ment. Data were collected on 146 different cows (63, 36, 18, 29 a in parity one to fourt, respectively) receiving different diets. The calibration model was developed using Foss wINISI 4 software on spectral data after applying the first derivative and using pLs regression. The CH4 emission prediction (g showed a calibration coefficient of determination (R2c) of 0.76, a cross-validation coefficient of determination (R2cv) and the standard error of calibration was of 62 g/day. Results are very promising and showed the possibility to predict the eructed CH4 from the milk spectra. relationship between measurements and predictions is linear and thereby allowing the distinction between low and high emitting cows.