The impact of P on absorbable P in dairy cattle rations Why the concern over P in dairy rations Reproductive efficiency Environment Phosphorus and Dairy Nutrition Perceived relationship of P content of dairy 120 rations and 100 reproductive 80 60 performance. 46.8 51.6 Days 40 20 Summary of 13 trials, 785 cows Low P (.32 -.40) High P (.39 -.61) 71.7 74.3 103.5 102.1 0 Days to 1st Estrus Days to 1st AI Days Open Satter and Wu, 1999 1
Impact on environment Prevalence of economically priced byproduct feed ingredients which are high in P Phosphorus Nutrition of Dairy Cattle NRC 2001 Assumes P bio of.64 to.70. Default value is.70 Assumes Phytate P is relatively digestible by ruminants 2
Virginia Tech Research on P Bio Differences in Key Feedstuffs Feed Ingredient Total available VT Total available NRC Alfalfa Hay 0.76 0.64 Alfalfa Silage 0.81 0.64 Corn Silage 0.82 0.75 Corn Gluten Feed 0.71 0.70 Corn Grain 0.65 0.70 High Moisture Corn 0.73 0.70 Dried Distillers 0.73 0.70 Hominy 0.64 0.70 Soybean Meal 0.66 0.70 Wet Brewers grains 0.69 0.70 Impact of P bio on dairy rations Scenarios Cow 52 months old 1500 lb. (682 kg) 85 lb. (38.6 kg) milk w/ 3.5% fat, 3.0% true protein 100 days in milk Feed Analyses NRC values in 2001 model Scenarios dairy rations formulated using NRC or VT bio. Standard diet minimal byproducts Byproduct diet reduced corn and soybean meal and replaced with corn gluten feed, distillers grains, hominy feed and wet brewers grains. 3
Standard Diet Feed Names Lb. DM/DAY Legume forage silage 7.42 Corn silage 25.34 Corn grain, ground, dry 7.92 Soybean meal, solv, 48% 4.45 Blood meal, ring dried 0.64 Whole cottonseed 3.60 Hydrol. Tallow 0.49 Limestone 0.49 Calcium phosphate (di) Magnesium oxide 0.05 Salt 0.15 Sodium bicarbonate 0.30 Selenium 0.01 Vitamin premix 1 0.15 Standard diet DMI 51.0 lb. (23.2kg) DMI predicted 55.1 lb. (25.0 kg) NE allowable milk 86.5 (29.3 kg) MP allowable milk 83.1 (37.8 kg) Total P requirement = 0.131 lb. (59.5g) Total absorbable P supplied 0.128 lb (58.1g) Balance 0.003 lb. (1.4g) Standard diet RDP balance +0.338 lb. (153g) RUP balance 0.103 lb. (46.8g) CP 16.7% NE l.74 Mcal / lb (1.63 Mcal/kg) NDF 33.6% of DM Forage NDF 27.7% ADF 22.2% Ca 0.8% P 0.3% EE 5.0% 4
Byproduct diet Feed Names Lb. DM/DAY Legume forage silage 6.18 Corn silage 19.36 Corn grain, ground, dry 2.64 Soybean meal, solv, 48% 1.78 Blood meal, ring dried 0.46 Hominy feed 6.30 Brewers grains, wet 4.20 Corn distillers grain w/sol. 6.44 Corn gluten feed 2.70 Limestone 0.50 Calcium phosphate (di) 0.00 Magnesium oxide 0.05 Salt 0.15 Sodium bicarbonate 0.30 Selenium 0.01 Vitamin premix 1 0.15 Byproduct diet DMI 51.2 lb. (23.3 kg) DMI predicted 55.1 lb. (25.0 kg) NE allowable milk 85.6 (38.9 kg) MP allowable milk 88.9 (40.4 kg) Total P required 0.131 lb. = 59.4 g Total absorbable P supplied 0.175 lb. = 75.8 g Balance +0.044 lb. = +19.9 g Byproduct diet RDP balance +0.73lb. RUP balance +.214lb. CP 18.1% NE l 0.73 Mcal/lb. (1.61 Mcal / kg) NDF 35.5% of DM Forage NDF 21.4% ADF 20.4% Ca 0.7% P 0.5% EE 4.1% 5
Comparison of Diets Using New Bio Values Diets P required Absorbable P Supplied Balance Standard diet w/nrc Standard diet w/new Byproduct diet w/nrc Byproduct diet with new 0.131 0.125 0.012 (5 gms) 0.131 0.128 0.003 (1.4gms) 0.131 0.167 +.036 (16 gms) 0.131 0.175 +0.044 (20gms) 1500 lb. body weight, 85 lb. milk @ 3.5% fat, 3.0% true protein, 52 months Additional Considerations for P Balance in Dairy Cattle Rations P content of common ration ingredients Mid Atlantic States c Ingredient NRC a Va. Tech Study b Average SD + SD Alfalfa 0.35 0.32 0.35 0.3 0.4 Corn silage 0.26 0.23 0.24 0.21 0.27 Corn 0.30 0.29 0.3 0.26 0.34 Soybean meal 0.70 0.74 0.73 0.71 0.74 (48%) Hominy 0.65 0.50 0.56 0.45 0.67 Corn gluten feed 1.0 1.08 1.0 0.9 1.12 Distillers grains 0.83 0.75 0.9 0.81 0.99 Wet brewers 0.59 0.65 0.65 0.5 0.8 grains a 2001 NRC values b Stewart et al. 2010 c Cumberland Valley Analytical Services 8/1/2012 8/1/2013 Corn silage 6
Corn gluten feed Dried distillers grains Comparison of Diets Using New Bio Values Diets P required Absorbable P Supplied Balance Standard diet w/nrc Standard diet w/new Byproduct diet w/nrc Byproduct diet with new 0.131 0.125 0.012 (5 gms) 0.131 0.128 0.003 (1.4gms) 0.131 0.167 +.036 (16 gms) 0.131 0.175 +0.044 (20gms) 1500 lb. body weight, 85 lb. milk @ 3.5% fat, 3.0% true protein, 52 months 7
Take Home Message VT research P from forages appears higher than NRC. P is lower in byproduct feeds. P is higher in fermented feeds and forages. Take home message Given the new information on what is impact on rations and nutrient balance? Diets with low inclusion of byproduct feeds in rations appear to have adequate P without inorganic P supplementation. Rations with higher inclusion byproduct inclusion rates have modest surpluses of dietary P. Nutrient analysis of feeds from large scale testing labs and field trials show substantial variation in P levels Supplementation of inorganic P may only be necessary for: High producing early lactation cows Farms with low P soils which is uncommon in much of the U.S. Additional studies by Va. Tech workers have demonstrated that achieving low P rations adds additional expense to dairy rations. 8
Rations with high inclusion rates of byproduct feeds were higher in CP. Our example with similar DMI and energy balance there was 0.75 lb. more protein per cow per day. Impact on P balance on dairies? Improved feeding management showed trends for improvements in N balance on 8 study herds over 5 year period. Improved feeding management had little impact on P balance on these same study herds. Impact of byproduct feeds. Higher levels of P in feeds than anticipated. Lack of supplemental inorganic P supplement. 9