Factors Affecting Enteric Emission Methane and Predictive Models for Dairy Cows.

Enteric methane emission is the main source of greenhouse gas contribution from dairy cattle. Therefore, it is essential to evaluate drivers and develop more accurate predictive models for such emissions. In this study, we built a large and intercontinental experimental dataset to: (1) explain the effect of enteric methane emission yield (g methane/kg diet intake) and feed conversion (kg diet intake/kg milk yield) on enteric methane emission intensity (g methane/kg milk yield); (2) develop six models for predicting enteric methane emissions (g/cow/day) using animal, diet, and dry matter intake as inputs; and to (3) compare these 6 models with 43 models from the literature. Feed conversion contributed more to enteric methane emission (EME) intensity than EME yield. Increasing the milk yield reduced EME intensity, due more to feed conversion enhancement rather than EME yield. Our models predicted methane emissions better than most external models, with the exception of only two other models which had similar adequacy. Improved productivity of dairy cows reduces emission intensity by enhancing feed conversion. Improvement in feed conversion should be prioritized for reducing methane emissions in dairy cattle systems.

Mathematical models for estimating the parameters of ruminal degradation kinetics of protein concentrates / Modelos matemáticos para estimação dos parâmetros da cinética de degradação ruminal de concentradosprotéicos

Objetivou-se com este estudo avaliar os parâmetros da cinética de degradação ruminal dos concentrados protéicos, farelo de soja(FS) e torta de algodão(TA). Para estimativa dos parâmetros da cinética de degradação in situ da matéria seca (MS) e proteína bruta (PB) dos concentrados, foi realizado o ajuste de 5 diferentes modelos matemáticos não-lineares: Exponencial, Van Milgen, Logístico, Gompertz e Richards. Para avaliação in situ dos alimentos, foram utilizados dois bovinos adultoscanuladosno rúmen. As amostras foram incubadas nos tempos 0; 2; 4; 6; 12; 16; 24; 36; 48 e 72 horas, nos resíduos de incubação foram determinados os teores de MS e PB, e sua degradabilidade potencial e efetiva. Os valores de degradabilidade efetiva da MS do FS foram de 86,35; 74,23 e 65,50%,e da TA de 53,44; 41,70 e 35,21% nas taxas de passagem de 0,02; 0,05 e 0,08.h-1, respectivamente. O FS e a TA apresentaram valores para a fração A da PB de 18,15 e 34,77% e para a fração B, 79,76 e 55,10%, respectivamente. De acordo com a ponderação de Akaike (Wi) o modelo de Richards apresenta; 95,45 e 49,64% de chance de ser o modelo mais adequado, para caracterizar a cinética de degradação in situ da MS do, FS e da TA, respectivamente. Contudo, o modelo de Gompertz apresenta 63,86 e 66,49 % de chance de ser o modelo mais adequado para caracterizar a degradação da PB do FS e TA.

This studied aimed to evaluate the parameters of ruminal degradation kinetics of protein concentrates, soybean meal (SM) and cotton cake (CC).To estimate the in situ degradation parameters of DM and CP from coproducts were fitted 5different non-linear mathematical models: Exponencial, Van Milgen, Logístico, Gompertz and Richards. For in situ evaluation were used two cattle cannulated in the rumen. The samples were incubate dat 0, 2, 4, 6, 12, 16, 24, 36, 48 and 72 hours and in the incubation residues were determined DM and CP and their degradability. The DM degradability of SM were 86.35, 74.23, 65.50% and to CC were 53.44, 41.70 and 35.21% in passage rates of 0.02; 0.05 and 0.08.h-1, respectively. The SM and CC showed values for the CP soluble fraction of the 18.15, 34.77% and 79.76, 55.10% to insoluble potentially degradable fraction, respectively. According to the Akaike weights (Wi) the model of Richards has 95.45 and 49.64% of chance to be the most suitable model to characterize the in situ DM degradation of SM and CC. However, the Gompertz model has 63.86 and 66.49% chance to be the most suitable model to characterize the CP in situ degradation of SM and CC.

Mathematical models for estimating the parameters of ruminal degradation kinetics of protein concentrates / Modelos matemáticos para estimação dos parâmetros da cinética de degradação ruminal de concentradosprotéicos

Objetivou-se com este estudo avaliar os parâmetros da cinética de degradação ruminal dos concentrados protéicos, farelo de soja(FS) e torta de algodão(TA). Para estimativa dos parâmetros da cinética de degradação in situ da matéria seca (MS) e proteína bruta (PB) dos concentrados, foi realizado o ajuste de 5 diferentes modelos matemáticos não-lineares: Exponencial, Van Milgen, Logístico, Gompertz e Richards. Para avaliação in situ dos alimentos, foram utilizados dois bovinos adultoscanuladosno rúmen. As amostras foram incubadas nos tempos 0; 2; 4; 6; 12; 16; 24; 36; 48 e 72 horas, nos resíduos de incubação foram determinados os teores de MS e PB, e sua degradabilidade potencial e efetiva. Os valores de degradabilidade efetiva da MS do FS foram de 86,35; 74,23 e 65,50%,e da TA de 53,44; 41,70 e 35,21% nas taxas de passagem de 0,02; 0,05 e 0,08.h-1, respectivamente. O FS e a TA apresentaram valores para a fração A da PB de 18,15 e 34,77% e para a fração B, 79,76 e 55,10%, respectivamente. De acordo com a ponderação de Akaike (Wi) o modelo de Richards apresenta; 95,45 e 49,64% de chance de ser o modelo mais adequado, para caracterizar a cinética de degradação in situ da MS do, FS e da TA, respectivamente. Contudo, o modelo de Gompertz apresenta 63,86 e 66,49 % de chance de ser o modelo mais adequado para caracterizar a degradação da PB do FS e TA.(AU)

This studied aimed to evaluate the parameters of ruminal degradation kinetics of protein concentrates, soybean meal (SM) and cotton cake (CC).To estimate the in situ degradation parameters of DM and CP from coproducts were fitted 5different non-linear mathematical models: Exponencial, Van Milgen, Logístico, Gompertz and Richards. For in situ evaluation were used two cattle cannulated in the rumen. The samples were incubate dat 0, 2, 4, 6, 12, 16, 24, 36, 48 and 72 hours and in the incubation residues were determined DM and CP and their degradability. The DM degradability of SM were 86.35, 74.23, 65.50% and to CC were 53.44, 41.70 and 35.21% in passage rates of 0.02; 0.05 and 0.08.h-1, respectively. The SM and CC showed values for the CP soluble fraction of the 18.15, 34.77% and 79.76, 55.10% to insoluble potentially degradable fraction, respectively. According to the Akaike weights (Wi) the model of Richards has 95.45 and 49.64% of chance to be the most suitable model to characterize the in situ DM degradation of SM and CC. However, the Gompertz model has 63.86 and 66.49% chance to be the most suitable model to characterize the CP in situ degradation of SM and CC.(AU)