Rob Bailey, President

A major environmental concern as of late is that of the overuse of phosphorous (P). It is thought that excessive P in fertilizer and animal feed could affect wetlands and waterways. This excessive P causes algae blooms which severely decrease the amount of oxygen available to aquatic life. How concerned should we be?

Over the last 10 to 12 years, ration levels of P for lactating cows has increased considerably, with 0.5% of total ration being normal in high producing herds. I see some competitive rations at 0.6% which I feel is way too high and not necessary. "Nutrient Requirements of Dairy Cattle" (NRC-1989) pegs the requirement at 0.42% for higher producing cows, and 0.49% for early lactation cows. It should be noted that early lactation cows have the same need forP as higher producers, but their dry matter intake is considerably less the first six weeks of lactations, hence the higher percentage needed in the diet.

At ANC, our standard recommendation has been within these ranges, typically varying from 0.42% to 0.50% at 100 pounds of milk. I did some figuring on cows fed our individual feeding schedule program. In this situation, our requirements change with milk production, and if we limited P to a maximum of 0.44%, we would save approximately $0.01 per cow per day. This would add up to $365 for 100 cows over one year's time. If, in fact, all of this was wasted P, which is a matter of conjecture, we would be putting an extra 450 pounds of phosphorus on our ground, which would only be 1.6 pounds per acre for 285 acres. If we had a one group TMR where we cannot increment the use of P based on production, this figure would rise to approximately 1100 pounds of P, which spread over 285 acres would come to 3.8 lbs/acre. However, the amount of P used in corn silage/acre = 31 pounds, in alfalfa/acre = 36 pounds, in soybeans/acre = 17.5 pounds, in corn grain/acre= 18 pounds, and in small grains/acre =12-15 pounds. So, if runoff into waterways is not a problem, the P is worked into the soil quickly, and your manure system is working efficiently, you may not have any problem, assuming you are soil testing and fertilizing accordingly.

Feeding higher amounts of P has helped to improve breeding on the farm level, but hasn't shown much improvement in research. I feelthis has something to do with how strong a heat a cow shows. In a research environment, more people are involved in heat detection! Some articles indicate a much greater savings and higher environmental risk. We at ANC are taking a more reasonable approach, and do not want a reduction in performance from cows on our program. It is also reasonable to assume that not all cows get everything the dairyman feeds, and as they say, an ounce of prevention is worth a pound of cure!