Work

Increasing concentrate feeding level in early lactation dairy cows fed cut herbage linearly decreased methane yield and intensity

Year: 2025

Type: article

Abstract: The use of supplementary feeds, including concentrates, on New Zealand dairy farms has increased in recent decades and this could have mitigated methane (CH 4 ) emissions by decreasing the forage-to-concentrate ratio. The forage-to-concentrate ratio in the diet can be easily managed in cows that receive a total mixed ration , but under grazing conditions, the cows select their own diets by increasing or decreasing the herbage intake, likely depending on the amount of concentrates eaten. The feed selection will have a direct effect on the forage-to-concentrate ratio and the potential mitigation of CH 4 emissions. The objective of the current study was to determine the effect of feeding increasing levels of concentrates in pasutre fed early lactation dairy cows on CH 4 emissions. Thirty-two early lactation dairy cows fed fresh cut ryegrass-based herbage ad libitum were allocated to receive 0, 2, 4 and 6 kg dry matter of concentrates ( n = 8 per treatment) per day in two equal meals during milking. The cows were on their respective full treatment diets for at least 14 days before CH 4 measurements started. The CH 4 emissions were measured in respiration chambers for 48 h. The CH 4 yield (g/kg dry matter intake) and intensity (g/kg milk solids) decreased linearly by 0.76 and 5.3 units per kg of concentrate in the diet ( P = 0.001 and P = 0.009), respectively, with increasing the concentrate level. The variations in CH 4 emissions after each feeding increased quadratically and linearly ( P = 0.023 and P = 0.038) after morning and afternoon feeding, respectively and the CH 4 emissions reached the peak more rapidly after morning feeding (linear effect; P = 0.029) when the concentrate level increased. For short-chain fatty acids, the proportion of acetate decreased by 0.72 units ( P = 0.003) while the proportion of propionate increased by 0.16 units ( P = 0.006) per kg of concentrate in the diet. Feeding concentrates is a simple feeding strategy to mitigate CH 4 emissions from dairy cows. CH 4 yield decreased linearly by increasing the concentrate inclusion level of the diet.

Source: Animal nutrition

DOI: 10.1016/j.aninu.2025.01.008