Nutritive value of maize forage silage fed to dairy cows for an integrated system of grain and milk production in Kenya
Three experiments were carried out to determine i) the quantity and composition of maize forage harvested at different stages of growth, ii) the effect on the milk yield of dairy cows fed on maize forage silages harvested at two stages of maturity together with two levels of dairy concentrate, iii) the effect of supplementing early and late cut silages with either dairy concentrate or cottonseed cake on dry matter intake and milk yield of dairy cows. Forage dry matter yield showed a small non-significant increase with advancing maturity. The contents of dry matter, ash, acid detergent fibre and lignin increased significantly with crop maturity. Crude protein content and dry matter degradability declined significantly as the crop matured. Grain and stover production were significantly reduced by early defoliation. The effects of stage of maturity on the composition of forage and the yields of grain and stover were smaller in the last three stages of defoliation. The effect of type of silage on dry matter intake was inconsistent in the three feeding trials. Dairy cows consumed similar amounts of either early or late cut maize silage in the first year. In the second trial, cows that were fed on early silage ate significantly higher amounts of silage dry matter than those fed on late silage. In the third year the opposite trend was observed. Within each silage, level and type of concentrate offered to the animals had no influence on silage intake. There were no substitution effects in the two feeding trials when different amounts of concentrate were fed with the silages. Milk production from cows that were fed on early silage was about 10% higher than that of cows fed on late silage. This difference was significant in two years. The higher level of concentrate supplementation gave 9% more milk than the lower level. Feeding the silages with dairy concentrate rather than cottonseed cake gave more milk per cow per day. There were no interactions between silage and concentrate effects on milk yield. Milk production when cows were grazing followed similar trends to those recorded in the silage feeding periods. The cows that were supplemented with four kg of concentrate partitioned more energy towards body weight gain than those fed on two kg of concentrate. Efficiency of utilisation of energy for milk production was lower when cows received four rather than two kg of concentrate. Metabolisable energy in early silage was better utilised for milk production than that in late silage. Feeding the two silages with cottonseed cake improved efficiency of energy utilisation for milk production.