论文部分内容阅读
在维多利亚州的Kyabram地区,笔者用二年的时间,在施氮肥和不施氮肥的灌溉多年生草场上,研究了奶牛放牧强度及其生产力之间的关系。奶牛以4.4—8.6头/公顷的放牧强度在草场上轮牧。每年对施氮肥处理牧地按5.6公斤氮/公顷的比例,表施氮肥4次。试验发现,每公顷牧地每增加一头奶牛,第1、2年的乳产量分别下降260和329公斤,乳脂产量分别下降12.3和15.5公斤,蛋白产量分别下降10.7和14.5公斤。第1年放牧强度为8.6头/公顷的,其乳和乳脂产量最高(分别为17900和847公斤/公顷);放牧强度为7.6头/公顷的,其蛋白产量最高(597公斤/公顷)。第2年每公顷牧地生产乳品产量达到最高后下降,放牧强度为6.6头/公顷的,乳和乳脂产量最高(分别为14180和675公斤/公顷),放牧强度为5.9头/公顷的,其蛋白产量最高(508公斤/公斤)。试验期间,增加放牧强度也降低了奶牛的体重。表施氮肥对每头奶牛总的乳和乳脂产量无什么影响,但使蛋白产量持续增加。在放牧强度为4.4和8.6头/公顷时,施氮肥使每头奶牛增产蛋白质的数量为2—7公斤。施氮肥还增加了奶牛体重,且在放牧强度较高时增加量也较大。第2年,在放牧强度为4.4、6.6和8.6头/公顷时,年平均生产1公斤乳脂需饲料干物质(牧草和添加料)分别为29.9、29.3和37.0公斤。
In Kyabram, Victoria, I used two years to study the relationship between grazing intensity and productivity of dairy cattle in nitrogenous and irrigated perennial pastures. The cows wheaten in the pasture with a grazing intensity of 4.4-8.6 ha / ha. Nitrogen fertilizer was applied four times a year to the pasture at a rate of 5.6 kg N / ha. The trial found that for each additional hectare of pasture, the first and second year milk production decreased by 260 and 329 kg respectively, the milk fat production decreased by 12.3 and 15.5 kg respectively, and the protein production decreased by 10.7 and 14.5 kg respectively. The first annual grazing intensity was 8.6 ha / ha, with the highest milk and milk fat production (17900 and 847 kg / ha, respectively) and the highest protein yield (597 kg / ha) with grazing intensity of 7.6 ha / ha. In the second year, the output of dairy products per hectare reached the highest level and then dropped. The grazing intensity was 6.6 ha / ha, the highest milk and milk fat production (14180 and 675 kg / ha respectively) and grazing intensity 5.9 ha / ha The highest protein yield (508 kg / kg). During the experiment, increasing the grazing intensity also reduced the cow’s body weight. Table nitrogen fertilizer on each cow’s total milk and milk fat production no effect, but the protein yield continued to increase. At grazing intensities of 4.4 and 8.6 heads / ha, nitrogen fertilizer increased the amount of protein produced per cow by 2-7 kg. Nitrogen fertilizer also increased the body weight of dairy cows, and the increase was also greater at higher grazing intensities. In the second year, with an average annual yield of 1 kg of milk fat at feed intensities of 4.4, 6.6 and 8.6 heads / hectare, feed dry matter (forage and feed) was 29.9, 29.3 and 37.0 kg respectively.