Location and Agro-Climate of the Experimental Site The agronomical trial was conducted at the Cattle Research Station of the Bangladesh Livestock Research Institute (BLRI) during October, 2014 to December, 2015. The station was located at 23°42'0'' N, 90°22'30'' E at the altitude of 4 m above the sea level. The clayey textured soil of the station is strongly acidic (pH 4.5-5.7) containing a very little (<1.5%) organic matter and its classification belongs to the Madhupur Tract (Agro Ecological Zone 28) of Bangladesh. During the experimental period temperature ranged from 210C to 350C and humidity ranged from 50% to 75%.
Preparation of Experimental Plots During the month of October, 2014 the seed of native black were propagated sexually with the moisture contain of 5 to 7%; and kept two seeds in each polythene pouch containing sandy alluvial soil were sown, and saplings were raised up to an age of five weeks. The saplings were transplanted in predesigned experimental plots. Before transplantation, the soil of the plots was ploughed and fertilized with a basal dose of cattle dung (@ 3.0 tons/hectare) and 50% of required chemical fertilizers (a mix of Urea, Triple Super Phosphate (TSP) and Murat of Potash (MP) at a ratio of 90:30:15 kg per hector of N: P: K, and all other related agronomical practices e.g. weeding, irrigation etc were common.
Experimental Layout Design and Treatment A uniformly plain land area of 63 m2 was divided into four (4) blocks, each of 15.75 m2 separated by 0.1 meter wide walking alleys. Each block was again divided into seven (7) experimental plots, each of 1.0 m2 for planting of 9 saplings at a space of 0.3mx0.3m per sapling. In harvesting day, Black Seed Variety (BSV) were harvested at different harvesting height such as 20cm; 40cm; 60cm & 80cm respectively above the ground level at 60 days and arranged in a Randomized Block Design (RBD) to determine the production response.
Yield Determination and Sample Collection After a post-transplantation growth period of 90 days, top plant parts with leaves (tops) were harvested at a 60 days interval from different harvesting height. The plants were allowed to grow after each cut and fertilized after each harvest with 60 kg Urea N/ha. The biomass yield of each of four harvesting height in different cuts of a year was added to determine annual yield of biomass production, and a total of six cuts were given. Survival rate (% of saplings grew after transplantation), number of prunes per plant and the relative growth rate of biomass were determined at different harvesting times. Fresh tops were harvested avoiding any surface water on plants and weighed on a top loading balance and fresh yield per plot was recorded. Fresh yield (kg or ton) was converted to DM yield plot-1 ha-1 according to the equation: DM yield plot-1 = Weight of fresh material × DM (%).
Chemical Analysis The tops were manually separated into stem and leaves to determine stem to leaf ratio and weighed accordingly. Representative samples of tops, stem and leaves were taken to determine fresh dry matter, total ash, crude protein (CP) and ether extract (EE) according to AOAC and neutral (NDF) or acid detergent Fiber (ADF) according to Van Soest. All the analyses were done in the animal nutrition laboratory of the BLRI. The tops and stems were chopped manually at a range of 0.03 m to 0.05 m, dried in the sun and milled for chemical analyses of biomass of different harvests.
Statistical Analysis Considering four different harvesting height of Moringa as treatment their responses to biomass production performances (yield, growth rate, pruning efficiency and ratio of botanical fractions), and nutrient yield and contents (DM, CP, ADF or NDF) were analyzed in an ANOVA of a Randomized Block Design (RBD) using a general linear model of SPSS-17.0 statistical software program in a computer. Any significant differences in the rate and extent of DM degradability in- Sacco of Moringa tops of different cultivars were analyzed using an ANOVA of 4x4 Latin Square Design.