| As forage grass of herbivorous stockbreeding in agricultural areas was very short, academician Rong Tingzhao of Sichuan Agricultural University presented the idea for development of nutritive agriculture according to ecological characteristics in the southwestern areas and advantages or disadvantages of Euchlaena mexicana and Gaodan grass in agricultural areas at present, and then successfully selected and bred new forage maize variety-Yucao No.1 and Yucao No.2, which passed the provincial appraisal in July 2007, and were certified by Crop Authorization Committee of Sichuan province in October 2007. With the main materials of Zea Mexican Schard, Gaodan grass and newly bred forage maize Yucao No. 1 and Yucao No.2, the study on the yield and the quality of them were carried out, and the main factors which had an impact on them were also investigated. Then the key technologies of forage maize grown in Sichuan were discussed and ideas for industry development of forage maize were also presented. The main results were as follows:1. The results of study on Gaodan-grass,Zea mexicana and newly bred forage maize combination showed that the yield of Yucao No. 1 was better than other combinations. Its fresh matter and dry matter yield were 174045 kg·ha-1 and 22208 kg·ha-1 respectively, which were 26900 kg·ha-1(18.3%) and 29200 kg·ha-1(20.2%) higher than that of Gaodan-grass and Zea mexicana separately. And the dry matter yield of Sicao No.l was 3300 kg·ha-1(17.5%) and 6100 kg·ha-1(37.9%) higher than that of Gaodan-grass and Zea mexicana separately. Since 2004, forage maize were planted in some areas of Sichuan such as Ya'an, Xichong, Yanjiang, Hongya, Nanjiang, Wusheng, Dongxing, Luding, Jinchuan, and also in Yunnan, Chongqing, Gansu, Guangdong. From the results above all these place, the fresh yield of forage maize was 50% higher than that of CK. Furthermore, results from growth dynamic of forage maize indicated that its growth rate conformed to a logistic model, fitting equation was y=2983/1+25.6e-0.05x (y means grass length, x means growth days,r=0.995).2. The crude protein (CP) and nitrogen-free extract (NFE) content of forage maize were 17.57% and 48.73% respectively, which reached the highest at booting stage of the first harvest; the content of crude fiber (CF) was the lowest 21.65%; the content of ether extract (EE) and crude ashes (CA) were 4.30% and 7.75%. The crude protein (CP) and crude fiber (CF) yield of forage maize were 2788.2 kg·ha-1 and 4713.3 kg·ha-1 separately, which were higher than that of Gaodan-grass(2211.2 kg·ha-1和3952.3 kg·ha-1) and Zea mexicana (2128.4 kg·ha-1 and 2813.9 kg·ha-1) . The forage maize harvested four times in a year, and its average nutrition composition at each time were 15.1% (CP), 25.6% (CF), 3.1% (EE), 8.9% (CA), 47.3% (NFE), which were better than Gaodan-grass (CP: 14.6%, CF: 26.2%, EE: 4.0%, CA: 8.6%, NFE: 46.6%). The dissolvable sugar and amino-acid content of forage maize at the booting stage of the first harvest were 9.8% and 3.1% respectively. The Lysine content of forage maize (0.41%) was higher than Gaodan-grass (0.39%) and Zea mexicana (0.39%). Gross energy (GE), digestible energy (DE), metabolize energy (ME) and total digestible nutrient (TDN) were highest at booting stage or initial tasseling stage. Fresh and dry matter yield at initial tasseling stage were 101400 kg·ha-1 and 18350 kg·ha-1, and the content of crude protein (CP), crude fiber (CF), ether extract (EE), crude ashes (CA) and nitrogen-free extract (NFE) were 14.2%, 24.3%, 3.9%, 6.3% and 51.3%, respectively.3. The results of mowed height indicated that fresh yield, dry yield and CP yield of forage maize harvested at 220cm grass length were all significantly higher than that at 190cm grass length. NDF content was also larger, but CP and RFV content were lower. Fresh yield, dry yield and CP yield of forage maize harvested at 160cm grass length were all significantly lower than at 190cm, while CP and RFV content were higher. Accordingly, it was useful for green forage when mowed height was 25cm and grass length was 190cm, and it was useful for green silage when mowed height was 15cm and grass length was 220cm.The results of plant density showed that tillering number, culm diameter and dry matter content with plant density of 37500 plant/ha-1 reached the highest, 45000 plant/ha-1 followed and 52500 plant/ha-1 was the lowest. CP content, CP yield and RFV with plant density of 37500 plant/ha-1 were the largest, 45000 plant/ha-1 followed and 52500 plant/ha-1 was the lowest; NDF content with plant density of 37500 plant/ha-1 was the lowest while 52500 plant/ha-1 was the highest. Therefore, grass yield and forage nutritive value were better with the plant density of 45000 plant/ha-1.Nitrogen fertilizer amount and cutting interval time had a significant effect on yield and quality of Yucao No.1, but their interaction showed no significant effect on yield and quality of Yucao No.1. The gross fresh yield, dry yield, CP content, CP yield and RFV without nitrogen fertilizer were the lowest, which significantly lower than that with nitrogen fertilizer of 2.2 g/plant; while the gross fresh yield, dry yield, CP content, CP yield and RFV with nitrogen fertilizer of 2.2 g/plant was significantly lower than that with nitrogen fertilizer of 3.8 g/plant and 5.4 g/plant, whose gross fresh yield, dry yield, CP content, CP yield, NDF content and FRV were not significant. The gross fresh yield, dry yield, NDF content and CP yield with 65d cutting interval time were the highest, which were significantly higher than that with 55d and 45d; while the CP content and RFV with 65d were significantly lower than that with 45d. Therefore, it was useful for green forage when nitrogen fertilizer amount was 3.8 g/plant and cutting interval time was 45d, and it was useful for green silage when cutting interval time was 65d with the same nitrogen fertilizer amount.4. Dairy cows were bred by forage maize and hemarthriacompressa in Hongya in 2007, and the results showed that after breeding dairy cows with forage maize, the average of daily milk yield was 16.58 kg, and increased by 1.18 kg(7.66%) comparing with the CK which breeding dairy cows with hemarthriacompressa. Accordingly, the daily milk yield could obviously improved by breeding dairy cows with forage maize. In Nanjiang, the effect of forage maize and wild grass on the growing indexes such as weight of Nanjiang yellow cows by different feeding modes such as captive, grazing and conventional feeding were investigated. The results suggested that under captive feeding, the weight value-added of cows raised by 40% and 60% forage maize-Yucao No.1 (4.9kg/each) was higher than that by wild grass (2.00g/each); under grazing feeding, the effect of Yucao No.1 on the growth and development of yellow cows was not significant with that of wild grass. However, no matter captive feeding (4.9 kg,3.8 kg) or grazing feeding (4.6kg,4.5 kg) , the weight value-added of yellow cows raised by Yucao No.l was larger than that by conventional feeding, the CK (2.5kg).5. All above results indicated that forage maize with high yield and good quality was fit for planting in the southwestern areas. The study presented ideas for industry development, objectives and main measures of forage maize to put research findings into real productivity rapidly.
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