施肥和刈割日期对杂交狼尾草钙、磷、镁含量的影响及其与家畜需要的关系

Effect of N fertilization level and defoliation date on Ca,P and Mg mineral concentration in Hybrid Pennisetum and their relationship to ruminant requirements

研究了不同施肥处理和刈割日期对杂交狼尾草Ca、P和Mg含量的影响及其与家畜营养的关系,结果表明,有机肥的施用显著降低了植株Ca含量,对植株P和Mg含量无显著影响;随无机氮施用水平的提高,杂交狼尾草植株Ca和Mg含量显著提高,P含量显著降低;植株Ca、Mg含量均随刈割日期的推迟而显著提高,植株磷含量随刈割日期的推迟呈先降后升的规律;根据NRC推荐的饲养标准(奶牛、肉牛和绵羊),所有处理杂交狼尾草植株Mg含量均能满足家畜的需要,Ca:P为(0.95～2.67):1;利用杂交狼尾草饲喂高产奶牛时,应注意日粮中Ca、P的添加.

This study was conducted in order to determine the effects of both nitrogen fertilizer application and defoliation date on the mineral concentration of a Pennisetum Hybrid, and the consequential relationship with ruminant nutrient requirements. The results indicated that with applied manure forage Ca concentration decreased （P〈0. 05） ,whereas forage P and Mg concentrations were not affected （P〉0.05）. With increased N ap- plication levels forage Ca and Mg concentrations increased,while the P concentration decreased. Forage Ca and Mg concentrations increased with later defoliation dates. P concentration in forage was shown as high-low-lower-high. According to NRC recommendations,Mg concentration （0.30%-0.70%） from all treatments was adequate for a lactating dairy cow producing milk 35 kg/d,a lactating beef cow producing milk 8 kg/d,a pregnant, non-lactating dairy cow during the last month of gestation and a lactating ewe suckling twins. The ratio of Ca/ P was （0.95-2.67） ： 1,which is known to be a highly efficient ratio for ruminants. Attention should therefore be paid to the addition of Ca and P in diets when a lactating dairy cow is producing milk 35 kg/d when fed by Hybrid Penniseturn.