ABSTRACT
The economic feasibility of replacing corn grain with by-product from biscuit manufacture (BBM) as an energy source in the diet for purebred and crossbred native lambs raised in feedlot was evaluated. Four production systems were developed based on nutritional management and genetic groups: (PS1) purebred native lambs fed a conventional diet based on corn and soybean meal; (PS2) purebred native lambs fed a diet with BBM replacing 100% of the corn; (PS3) crossbred native lambs fed a conventional diet based on corn and soybean meal; and (PS4) crossbred native lambs fed a diet with BBM replacing 100% of the corn in the diet. The extrapolation was performed for a module of 24 Morada Nova (MN) breed lambs (12 MN red (MNR) and 12 ½MNR × ½MN white lambs)) with an initial body weight of 18.8 ± 0.875 and 15.0 ± 0.838 kg for MNR and crossbred, respectively. Feed, animal acquisition, and labor present the total production costs. The greatest profits were obtained in the production systems that fed the crossbred lambs with BBM. The lesser cost of BBM contributed to greater total factor productivity regardless of genetic group (1.095 vs. 1.015 for BBM and conventional feed, respectively). Systems using BBM (SP2 and SP4) showed an estimated payback of 5.44 and 3.24 years, respectively, while the use of conventional feed contributed to negative economic data (PS1 and PS3) with payback period greater than 10 years. The use of BBM as an energy source in the diet of crossbred sheep was economically feasible and showed better economic indices when compared to the systems using a conventional diet.
Subject(s)
Animal Feed , Zea mays , Animal Feed/analysis , Animals , Brazil , Diet/veterinary , Plant Breeding , Sheep/genetics , Sheep, Domestic/genetics , Zea mays/geneticsABSTRACT
Plant leaf stoichiometry reflects its adaptation to the environment. Leaf stoichiometry variations across different environments have been extensively studied in grassland plants, but little is known about intraspecific leaf stoichiometry, especially for widely distributed species, such as Stellera chamaejasme L. We present the first study on the leaf stoichiometry of S. chamaejasme and evaluate its relationships with environmental variables. S. chamaejasme leaf and soil samples from 29 invaded sites in the two plateaus of distinct environments [the Inner Mongolian Plateau (IM) and Qinghai-Tibet Plateau (QT)] in Northern China were collected. Leaf C, N, P, and K and their stoichiometric ratios, and soil physicochemical properties were determined and compared with climate information from each sampling site. The results showed that mean leaf C, N, P, and K concentrations were 498.60, 19.95, 2.15, and 6.57 g kg-1; the average C:N, C:P, N:P, N:K and K:P ratios were 25.20, 245.57, 9.81, 3.13, and 3.21, respectively. The N:P:K-ratios in S. chamaejasme leaf might imply that its growth is restricted by K- or K+N. Moreover, the soil physicochemical properties in the S. chamaejasme-infested areas varied remarkably, and few significant correlations between S. chamaejasme leaf ecological stoichiometry and soil physicochemical properties were observed. These indicate the nutrient concentrations and stoichiometry of S. chamaejasme tend to be insensitive to variations in the soil nutrient availability, resulting in their broad distributions in China's grasslands. Besides, different homeostasis strength of the C, N, K, and their ratios in S. chamaejasme leaves across all sites were observed, which means S. chamaejasme could be more conservative in their use of nutrients improving their adaptation to diverse conditions. Moreover, the leaf C and N contents of S. chamaejasm were unaffected by any climate factors. However, the correlation between leaf P content and climate factors was significant only in IM, while the leaf K happened to be significant in QT. Besides, MAP or MAT contribution was stronger in the leaf elements than soil by using mixed effects models, which illustrated once more the relatively weak effect of the soil physicochemical properties on the leaf elements. Finally, partial least squares path modeling suggested that leaf P or K contents were affected by different mechanisms in QT and IM regions, suggesting that S. chamaejasme can adapt to changing environments by adjusting its relationships with the climate or soil factors to improve its survival opportunities in degraded grasslands.
ABSTRACT
This two-year study evaluated the effect of Pennisetum purpureum genotypes under rainfed or irrigated conditions, during the dry and rainy seasons, on herbage, leaf, and stem dry matter (DM) accumulation rates, nutritive value, and carbohydrate and protein fractionation. Treatments were tall (Iri 381 and Elefante B) or dwarf (Mott and Taiwan A-146 2.37) genotypes under rainfed or irrigated conditions. Taiwan A-146 2.37 (146 kg DM ha per day) showed similar herbage accumulation rate (HAR) to tall genotypes during the rainy season (124 and 150 kg DM/ha per day, respectively). Dwarf genotypes showed differences in leaf accumulation rate (LAR) (66 and 49 kg DM/ha per day). Mott leaf had less neutral detergent fiber (NDF) (589 g/kg DM) than Taiwan A-146 2.37 (598 g/kg DM), and tall genotypes had generally greater NDF (668 g/kg DM) than the dwarf genotypes. Irrigation increased fiber deposition in the leaf. Stems of all genotypes had lower in vitro digestible dry matter (IVDDM) (378 g/kg DM) under rainfed conditions in the rainy season. Leaf from irrigated plots had 23% more carbohydrate C fraction (160 g/kg CHO) than those from rainfed plots (122 g/kg CHO). Dwarf genotypes had generally greater nutritive value than tall genotypes. These genotypes show promise under irrigation to fill forage gaps during dry periods.
