NUTRITIVE VALUE OF A NATIVE PASTURE DOMINATED BY Eragrostis plana Nees AND ITS RELATION WITH METABOLIC PROFILE OF PRIMIPAROUS COWS SUPPLEMENTED FROM PREGNANCY TO POSTPARTUM

Abstract The objective of this research was to evaluate the quality of the forage mass of a native pasture covered by 70% of Eragrostis plana Nees (South African lovegrass) under continuous grazing of primiparous cows. The following chemical characteristics of forage components leaves and stems of South African lovegrass and native species were evaluated: organic matter in vitro digestibility (OMIVD), crude protein (CP), and neutral detergent fiber (NDF). The protein and mineral metabolic profile in blood was associated with the supplements common salt, mineral salt, protein salt and reproduction salt. There was higher crude protein content in leaves and stems of South African lovegrass in winter (9.4% and 6.7) and spring (8.9% and 6.6), respectively. Metabolic protein in the blood did not differ among supplements (P> 0.05), but levels of albumin (34.5 to 25.3 g/L) and urea (36.2 to 30.1 mg/dL) decreased from winter to summer. There was deficiency of the average content of mineral phosphorus for cows supplemented with protein salt (3.9), mineral salt (3.3) and common salt (2.2) in spring and common salt (2.9 mg/ dL) in summer. Primiparous cows managed on native pasture with a prevalence of 70% coverage of South African lovegrass need mineral phosphorus supplementation with reproduction salt in spring and summer.

摘要
本研究旨在评估覆盖70%扁穗画眉草（Eragrostis plana Nees，South African lovegrass）的原生牧场在初产母牛连续放牧模式下的饲草质量。本研究对南非爱草及本土物种的叶片、茎秆两类饲草组分的以下化学特性进行了测定：体外有机物消化率（organic matter in vitro digestibility, OMIVD）、粗蛋白（crude protein, CP）及中性洗涤纤维（neutral detergent fiber, NDF）；同时探究了饲喂食盐、矿物盐、蛋白盐及繁殖盐补充剂对母牛血液蛋白质与矿物质代谢谱的影响。
结果显示，南非爱草的叶片与茎秆粗蛋白含量在冬季分别为9.4%与6.7%，春季分别为8.9%与6.6%，处于较高水平。血液代谢蛋白水平在各补充剂组间无显著差异（P>0.05），但白蛋白浓度从冬季的34.5 g/L降至夏季的25.3 g/L，尿素浓度从冬季的36.2 mg/dL降至夏季的30.1 mg/dL。
春季时，饲喂蛋白盐、矿物盐及食盐的母牛血清平均磷含量分别为3.9 mg/dL、3.3 mg/dL及2.2 mg/dL，均存在矿物磷缺乏问题；夏季饲喂食盐的母牛血清磷含量为2.9 mg/dL，同样存在磷缺乏情况。
在覆盖70%南非爱草的原生牧场中开展饲养管理的初产母牛，需在春季与夏季通过繁殖盐补充矿物磷。