Effects Of Probiotics On Nitrogen Emission In Dairy Cows

Nitrogen is the essential nutrient for animals. A multitude of studies show that urine, feces and other excrement containing excessive nitrogen excreted by dairy cows are able to pollute air, water and soil. Meanwhile, too much nitrogen which is discharged into environment cause waste and increase the cost of feeding.The objective of this experiment was to investigate the effects of different probiotics on urinary nitrogen, fecal nitrogen and milk nitrogen in lactating dairy cows.12 Chinese Holstein in early lactation (parity 2-3) were used in a replicated 4×4 Latin square design. Treatments were fed basal diet and provided four different probiotics:1) yeast culture,40g/d; 2) yeast bacteria,20g/d; 3) compound preparation of lactobacillus and bacillus,5g/d; 4) secretion of aspergillus,40g/d. The experiment lasted for 52 days with 13 days each period. During each period, the prelimitary period was on day 1 to day 10 followed by three-day sampling period. During the three-day sampling periods, milk, urine and faeces were collected twice daily for analysing milk nitrogen content, total nitrogen of urine, ammoniacal nitrogen of urine, pH of urine, urinary energy, organic matter of faeces, total nitrogen of faeces and water content of faeces. Results show that:(1) Four probiotics had no significant influence on milk fat content, milk protein content, SCC, milk lactose content and milk total solid content;(2) Fecal energy was increased by providing secretion of aspergillus, which decreased total phosphorus of urine, SCC and total nitrogen of faeces significantly (P <0.05);(3) Yeast bacteria decreased the fecal phosphorus, ammoniacal nitrogen of urine and total nitrogen of urine (P< 0.05). Furthermore, it increased milk content and content of fecal energy;(4) Compound preparation of lactobacillus and bacillus could significantly influence water content of faeces and organic matter of faeces (P< 0.05), and increase total milk solids content.