Impact of Crop Residue on Milk Yield and Methane Emissions in Dairy Cows: Evidence from Arusha City

Abstract

Smallholder dairy farming in urban areas utilize the crop residues as part of the basal diet. However, the quality of the feed materials is said to have greater contribution on the productivity and methane emission from the cow.The current study examined the effects of crop residue supplement on methane emission from lactating dairy cows. A total of 56 crossbred lactating dairy cows were investigated on the effect of four different crop residues feeds for a period of 90 days. The study had three cycles of farm visits of which each cycle had a period interval of 30 days. The feed intake was monitored in a last 30 days of the study where by feed offered and refusal were measured to quantify the amount ingested by the animal. There were four dietary treatments grouped according to the types of crops remains fed to animal (GM-for the cows fed on grass mixture only, MSM-for the cows fed on maize stover mixture, RSM-for the cows fed on rice straw mixture and BRM-for the cows fed on bean resides mixture). Methane emissions were measured directly from the nostril of the lactating dairy cow using laser methane detector (LMD) technique. Body weight and milk samples were collected simultaneously with methane measurement. Milk yield was obtained from the AADGG database. The data was analyzed by using JMP® Pro 18 version 2024 of SAS. The performance result showed that milk yield and body weight change were greater with (14.5 l/day/cow and 0.928kg/day) while the measured mean methane concentration due to respiration and eructation were lower from cows fed with BRM (14.072 and 72.75 ppm) than other treatments at P<0.05. The study concluded that use BRM improves cattle diet and increase animal productivity as well as reduce methane emission. Therefore, the study recommends further research on dairy cows fed crop residues treated with additives and enzymes on productivity and methane emission.