后备母牛的饲养管理appt课件.pptVIP

* Fewer papillae per unit area reflects bigger papillae with greater nutrient absorption capacity. Hence, with 2% XP the rumen was much more developed and capable of digesting complex carbohydrates and absorbing VFAs. An underdeveloped rumen may restrict calf growth for two to four weeks after weaning, adversely affecting time of breeding and subsequent age at first calving. * * The absorption of the fermentation end-products is an important criterion of ruminal development. In mature animals, VFA’s and other fermentation end-products are absorbed into the rumen epithelium where propionate and butyrate are metabolized. Then, the VFA’s or end products of metabolism (lactate and β-hydroxybutyrate) are transported to the liver for use as energy substrates. In neonatal calves there is little or no absorption or metabolism of VFA’s. Hence, the rumen must develop this ability prior to weaning. * * The rumen wall consists of epithelial and muscular layers. The muscular layer provides support for the interior (epithelial layer) and moves ruminal contents in the rumen. The epithelial layer is the absorptive layer containing many fingerlike projections called papillae. The papillae provide the absorptive surface for the rumen. At birth, the papillae are small and non-functional. They absorb little and do not metabolize significant VFA’s. The primary stimulus for papillae development are the VFA’s – particularly propionate and butyrate. Rumen development is driven by the availability of dry feed, especially the starter grain in the rumen. Calves should be offered a grain based starter ration and fresh, clean water, in addition to milk after their first day of life. * * * * * * * * * * * * * 发育牛/育成牛 1、饲 养 2、管 理 3、易出现的问题及解决措施 发 育 牛 特点: 生长发育最旺盛时期，疾病少，容易 管理。 要充分利用牛自身的“生长发育旺盛”的生理特点，除了能获得高的增重外，还要获得完美的内在器官发育及适应环境的能力。 繁育机能发育变化 荷斯坦牛的性成熟年龄大约在6-14月龄。生殖器重量的增加（♀）在6个月龄以前与体重增加是平行进行，其后发育超过体发育。10个月龄后变慢，荷斯坦牛的初情期约在10个月龄、体重250千克、体高110-115cm时出现。 乳腺发育 若实行高营养