Phosphorus Balance And Environmental Effects In The Intensive Dairy Production System

With the development of the intensive dairy farming, many dairy cows are fed in the smaller area with vast excrements discharged from dairy farms, which led to a serious of environmental pollution problems. In order to programme the reasonable scale of dairy farm, make full use of the phosphorus resources from excrements, improve dairy cows the utilization of phosphorus, and reduce the phosphorus pollution from the intensive dairy farm, the phosphorus element which played an important role in the water eutrophication was studied, the production and emission of phosphorus were surveyed and evaluated in the intensive dairy farm,and the balance and environment effects were analyzed in three levels including overall, group and individual,then the scientific basis and data foundation were provded for the practice.Test I: Taking the entire dairy farm with a thousand cows in Zheng zhou as the object, the whole balanced condition of input and output of phosphorus were calculated in the dairy farm. The specific design is taking heifers and cows as the main part, collecting and evaluating the feed quantity according to the diet compositon in four seasons, calculating the condition of input of phosphorus in the dairy farm by feed, calculating phosphorus quantity by the excrement, the sewage, the milk, analying the balance and environment effects of phosphorus element in the dairy farm. Result suggest: the input of phosphorus was 87454 kg through the feed all year round, the total phosphorus quantity was 5376.14 kg through the excrement, accounting for 61.47 % of the feed phosphorus, utilization rate of the phosphorus was 38.53%; output phosphorus of milk in dairy farm was 4320 kg all year round, accounting for 4.94 % of the feed phosphorus; the phosphorus quantity by sewage was 114.9kg all year round, accounting for 0.13% of phosphorus of the feed phosphorus. It is a main way to pollute environment by the sewage in the dairy farm, so we should take management of the sewage seriously. Moreover, according to the phosphorus balance of the dairy farm and nutrition requirement of phosphorus for the cow, the mathematical model of phosphorus balance of input and output was designed for the dairy farm: {(7.27+0.0215W+0.00602WG)Na+ [(0.0143W+0.99FCM)/0.50]Nb}D= [(N_yF_yP_y+N_mF_mP_m) + CV + NME]D + O+J. It can provide the scientific basis and the instruction for phosphorus discharge of the dairy farm.Testâ…¡: Taking part of heifers and cows as the object of a thousand dairy farm in Zheng zhou, the input and output of phosphorus were studied in the community level. The phosphorus in the feed, feces, and milk was determined respectively by raising 10 heifers and 10 cows. The phosphorus balance of heifers and cows was determined in the community level. Result suggest: daily average phosphorus excretion in feces and urine of heifer was 65.77g all year round, accounted for 48.71% of phosphorus in feed intake, the organism utilization was 52.84%; daily average phosphorus excretion in feces and urine of cow was 151.23 g all year round, accounted for 65.19% of phosphorus in feed intake, the organism utilization was 34.81%, phosphorus in the milk accounted for 7.14% in feed intake. If the phosphorus in the excrement was not processed well, it will pollute the environment possibily.Test III: Through the determination of phosphorus of a thousand dairy farm in Zheng zhou, the balance and environment effects of phosphorus were studied in individual level. The specific design is selecting 5 cows whose weights are close and to intake is normal, healthy and 5 heifers whose weights are around 300 kg and to intake is normal, healthy, taking one year as the unit. The feed, water of cows that riased limitedly in whole test procedure were consistent with convention. Throuth the determination of feed intake, fecal excretion, milk phosphorus content, digestibility and the environment effects of phosphorus were calculated.Result suggest: the digestibility of phosphorus of heifer was 49.35%, that of cow was 41.78%; daily average phosphorus excretion in feces and urine of heifer was 60.94g all year round, accounted for 47.16% of phosphorus in feed intake, the organism utilization was 52.84%; daily average phosphorus excretion in feces and urine of cow was 140.34g all year round, accounted for 57.89% of phosphorus in feed intake, the organism utilization was 42.11%, the phosphorus in the milk accounted for 7.14% in feed intake. The phosphorus content in feces was higher but in urine was extremely lower. The fecal phosphorus is the main factor affecting the environment, but the urine can not be ignored, because the phosphorus in the feces is washed easily by the flowing liquid into the environment to pollute the environment.