The objective of this study by Ewonetu Kebede of the Haramaya University, School of Animal and Range Sciences, Ethiopia, was to determine effect of replacing grass hay with maize silage on milk production and composition. The study was conducted at Haramaya University dairy research farm -using sixteen crossbred dairy cows (Zebu × HolsteinFriesian) which were assigned to two treatment groups.
Each treatment group consisted of eight cows and arranged in a completely randomized experimental design. Cows in both treatment groups were provided similar supplemental concentrate ration formulated from various ingredients but fed on different basal diets which were silage and grass hay.
The feeding trial was conducted for a total of 90 days. Milk yield of individual cows were recorded every day and analyzed every two weeks for its chemical composition. Data were analyzed by t-Test for means. The group of cows fed on grass hay relatively produced higher milk yield (17.1) than cows fed on silage (16.1 liters per day). The protein, total solid, solid not fat, and milk urea nitrogen composition were found significantly different between a group of cows fed grass hay and silage. Silage-fed cows gave higher percentage of fat and protein content throughout the experimental period. Milk urea-nitrogen concentration was intensive in cows fed on hay and it was higher than the acceptable range (12 to 18 mg/dl) for the two experimental diets.
The author thus concluded that farmers could use both grass hay and maize silage as substitute to each other in dairy cow diets that could ensure higher quantity and quality milk production.