# Presentation: 286176

## Feeding Strategies to Reduce N Losses From the Lactating Dairy Cow

**Glen Broderick**
**U.S. Dairy Forage Research Center**
**Madison, Wisconsin**

## Introduction

**1.****	****Dietary Crude Protein Supplies Absorbable Protein:**
**	****a.****	****Providing Rumen Degrad****ed**** Protein (RDP).**
**	****b.****	****Rumen Undegrad****ed**** Protein (RUP).**
**2.****	****Complex Relationships Among Diet Composition & Absorbable Amino Acids Supply:**
**	****a.****	****Energy Content Influences Microbial Protein.**
**	****b.****	****RDP & RUP Supplies Influenced by Intake.**
**	****c.****	****Nitrogen (Urea) Recycling to Rumen.**

## What’s Wrong With Feeding Excess Crude Protein

**1.****	****Not Economical--Protein Supplements Costly.**
**2.****	****Excretion of N has a Metabolic Cost.**
**3.****	****N Pollution of the Environment.**
**4.****	****Increasing Dietary CP Increases Excretion of the Most Labile N.**

## Effect of Dietary Crude Protein on Milk Yield & Nitrogen Excretion

## Some Literature Regarding Dietary [CP]

**1.****	**_**Grings et al. (1991):**_** Milk Yield Increased Linearly from 13.8 to 17.5% CP (CSM).**
**2.****	**_**Austin et al. (1991) & Akayezu et al. (1997):**_** Protein Yield Similar in Cows Fed 16 (+ RUP) & ~18% CP. **
**3.****	**_**Powers et al. (1995):**_** Milk Yield, [Protein] at 18% CP (28 kg/d, 3.19%) > 14% CP (27 kg/d, 3.14%).**

## Some Literature Regarding Dietary [CP] (#2)

**4.****	**_**Komaragiri**__** & Erdman (1997):**_** Protein Yield at 19% CP (1.29 kg/d) > 16% CP (1.15 kg/d).**
**5.****	**_**Kalscheur et al. (1999):**_** Yield on 17.4% CP > 15.2% (****≤ ****14 wks); 15.3% CP = 13.3% (19-29 wks).**
**6.****	**_**Castillo et al. (2000):**_** Above **_**15% CP**_**, 67% of the Extra N-Intake is Excreted in Urine.**

## Protein & Energy Levels (GAB53)

**1.****	****3 Protein Levels; 3 NDF (Energy) Levels at each Protein Level (9 diets).**
**2.****	****7-Squares of 9 Cows (63 Total: 45 Multips & 18 Heifers).**
**3.****	****Incomplete 9x9 Latin square; 4, 4-wk Periods.**
**4.****	****Yield of Milk & Milk Components; Intake; BW**
**5.****	****Urine & Fecal Grab Samples.**
**6.****	****Conservative Stats; e = cow(sq) for CP & NDF.**

## Diet Composition--High NDF

**Ingredient****	**** Low CP ****	****  Med CP ****	****High CP**
**	****	****	****	****(% of DM)**
**	****Alfalfa Silage****	****	****44****	****	****44****	****	****44**
**	****Corn Silage****	****	****31****	****	****31****	****	****31****	**
**	****Rolled HMSC****	****	****21****	****	****17****	****	****13****	**
**	****48% Soybean meal****	****	****1.0****	****	****5.3****	****	****9.8****	**
**	****Roasted soybeans****	****	****2.5****	****	****2.5****	****	****2.5****	**
**	****Sodium Bicarbonate****	****	****0.0****	****	****0.0****	****	****0.0****	**
**	****Minerals & Vitamins ****	****	****0.4****	****	****0.4****	****	****0.4****	**
_**Composition**_
**	****Crude protein****	****	****15.1****	****	****16.7****	****	****18.5****	**
**	****AS/Total Forage****	****	****	****	****59****	****	**
**	****NDF****	****	****	****	****36****	****	**
**	****NFC****	****	****	****	****37****	****	**

## Diet Composition--Medium NDF

**Ingredient****	**** Low CP ****	****  Med CP ****	****High CP**
**	****	****	****	****(% of DM)**
**	****Alfalfa Silage****	****	****37****	****	****37****	****	****37**
**	****Corn Silage****	****	****25****	****	****25****	****	****25****	**
**	****Rolled HMSC****	****	****31****	****	****27****	****	****22**
**	****48% soybean meal****	****	****2.9****	****	****7.3****	****	****11.8**
**	****Roasted soybeans****	****	****2.5****	****	****2.5****	****	****2.5**
**	****Sodium bicarbonate****	****	****0.3****	****	****0.3****	****	****0.3**
**	****Minerals and vitamins****	****0.4****	****	****0.4****	****	****0.4**
_**Composition**_
**	****Crude protein****	****	****15.2****	****	****16.7****	****	****18.4****	**
**	****AS/Total Forage****	****	****	****	****60****	****	**
**	****NDF****	****	****	****	****32****	****	**
**	****NFC****	****	****	****	****41****	****	**

## Diet Composition--Low NDF

**Ingredient****	**** Low CP ****	****  Med CP ****	****High CP**
**	****	****	****	****(% of DM)**
**	****Alfalfa Silage****	****	****31****	****	****31****	****	****31**
**	****Corn Silage****	****	****19****	****	****19****	****	****19****	**
**	****Rolled HMSC****	****	****42****	****	****37****	****	****33**
**	****48% soybean meal****	****	**** 4.8****	****	****9.3****	****	****13.7 ****	****Roasted soybeans****	****	****2.5****	****	****2.5****	****	****2.5**
**	****Sodium bicarbonate****	****	****0.6****	****	****0.6****	****	****0.6**
**	****Minerals and vitamins****	****0.4****	****	****0.4****	****	****0.4**
_**Composition**_
**	****Crude protein****	****	****15.1****	****	****16.6****	****	****18.3****	**
**	****AS/Total Forage ****	****	****	****	****61****	****	**
**	****NDF****	****	****	****	****28****	****	**
**	****NFC****	****	****	****	****46****	****	**

## Production--CP Levels

**Ingredient****	**** 15.1% CP ****	****16.7% CP ****	****18.4% CP****	****Linear P**
**	****DMI, kg/d****	****	****21.1****	****	****22.3****	****	****22.6****	****	****0.03****	**
**	****Milk, kg/d****	****	****32.8****	****	****34.6****	****	****34.4****	****	****0.48****	**
**	****Fat, kg/d****	****	****1.15****	****	****1.24****	****	****1.20****	****	****0.33****	**
**	****Protein, kg/d****	****	****0.98****	****	****1.03****	****	****1.02****	****	****0.46****	**
**	****SNF, kg/d****	****	****2.95****	****	****3.06****	****	****3.06****	****	****0.62****	**
**	****MUN, mg/dL****	****	****9.2****	****	****12.4****	****	****16.0****	****	****< 0.01****	****Milk N/N Intake****	****0.31****	****	****0.28****	****	****0.25****	****	****< 0.01****	****Urinary N, g/d****	****	****119****	****	****169****	****	****227****	****	****< 0.01****	****Fecal N, g/d****	****	****231****	****	****264****	****	****278****	****	****0.04**

## Production--NDF Levels

**Ingredient****	**** 36% NDF ****	****32% NDF ****	****28% NDF****	****Linear P**
**	****DMI, kg/d****	****	****21.7****	****	****22.1****	****	****22.1****	****	****0.84****	**
**	****BW gain, kg/d****	****	****0.39****	****	****0.47****	****	****0.71****	****	****0.02****	**
**	****Milk, kg/d****	****	****31.4****	****	****33.8****	****	****36.5****	****	****< 0.01****	**
**	****FCM, kg/d****	****	****33.0****	****	****34.8****	****	****34.4****	****	****0.32****	**
**	****Fat, kg/d****	****	****1.20****	****	****1.24****	****	****1.15****	****	****0.48****	**
**	****Protein, kg/d****	****	****0.92****	****	****1.01****	****	****1.10****	****	****< 0.01****	**
**	****True protein, kg/d****	****0.85****	****	****0.94****	****	****1.03****	****	****< 0.01****	**
**	****MUN, mg/dL****	****	****13.3****	****	****12.7****	****	****11.5****	****	****< 0.01****	****Milk N/N Intake****	****0.26****	****	****0.27****	****	****0.30****	****	****< 0.01****	****Urinary N, g/d****	****	****182****	****	****175****	****	****158****	****	****0.10****	****Fecal N, g/d****	****	****253****	****	****259****	****	****262****	****	****0.64**

## Effect of Diet on Milk Yield  (GAB53)

## Effect of Diet on Protein Yield  (GAB53)

## Approaches to Reducing Dietary CP

**1.****	****Accurate Tracking of Dietary CP Intake (MUN?).**
**2.****	****Feed Hay Rather Than Silage.**
**3.****	****Reduce NPN in Hay-Crop Silage.**
**4.****	****Dilute Hay-Crop Silage with Corn Silage.**
**5.****	****Feed More Concentrate (as Much as Possible?).**
**6.****	****Match CHO & CP Fermentation.**
**7.****	****Feed By-Pass Protein & Essential AA.**
**8.****	****Use “N-Free” Essential AA (eg, MHA).**

## Approaches to Reducing Dietary CP

**1.****	****Accurate Tracking of Dietary CP Intake (MUN?).**
**2.****	****Feed Hay Rather Than Silage.**
**3.****	****Reduce NPN in Hay-Crop Silage.**
**4.****	****Dilute Hay-Crop Silage with Corn Silage.**
**5.****	****Feed More Concentrate (as Much as Possible?).**
**6.****	****Match CHO & CP Fermentation.**
**7.****	****Feed By-Pass Protein & Essential AA.**
**8.****	****Use “N-Free” Essential AA (eg, MHA).**

## Single Factor Regressions on Milk Urea N (MUN) Using Mixed Effects Models (Broderick & Clayton, 1997)

**Factor****	****Equation****	****ddf****	****R****2**

**CP, % of DM****	****Y = 0.269 MUN (mg/dl) + 13.7****	****479****	****0.84**
**Rumen NH****3****-N,****	****Y = 0.686 MUN (mg/dl) + 6.43****	****205****	****0.57 mg/dl**

## Relationship of CP Intake & MUN  (GAB53)

## Relationship of Urinary N to MUN  (GAB53)

## Approaches to Reducing Dietary CP

**1.****	****Accurate Tracking of Dietary CP Intake (MUN?).**
**2.****	****Feed Hay Rather Than Silage.**
**3.****	****Reduce NPN in Hay-Crop Silage.**
**4.****	****Dilute Hay-Crop Silage with Corn Silage.**
**5.****	****Feed More Concentrate (as Much as Possible?).**
**6.****	****Match CHO & CP Fermentation.**
**7.****	****Feed By-Pass Protein & Essential AA.**
**8.****	****Use “N-Free” Essential AA (eg, MHA).**

## Effect of Fish Meal (FM) Supplementation of Diets with 50% Alfalfa Silage or Hay (Vagnoni & Broderick, 1997)

## Approaches to Reducing Dietary CP

**1.****	****Accurate Tracking of Dietary CP Intake (MUN?).**
**2.****	****Feed Hay Rather Than Silage.**
**3.****	****Reduce NPN in Hay-Crop Silage.**
**4.****	****Dilute Hay-Crop Silage with Corn Silage.**
**5.****	****Feed More Concentrate (as Much as Possible?).**
**6.****	****Match CHO & CP Fermentation.**
**7.****	****Feed By-Pass Protein & Essential AA.**
**8.****	****Use “N-Free” Essential AA (eg, MHA).**

## Reducing NPN in Alfalfa Silage Reduces Excess Rumen Ammonia & Improves Milk Production (Nagel & Broderick, 1992)

## Approaches to Reducing Dietary CP

**1.****	****Accurate Tracking of Dietary CP Intake (MUN?).**
**2.****	****Feed Hay Rather Than Silage.**
**3.****	****Reduce NPN in Hay-Crop Silage.**
**4.****	****Dilute Hay-Crop Silage with Corn Silage.**
**5.****	****Feed More Concentrate (as Much as Possible?).**
**6.****	****Match CHO & CP Fermentation.**
**7.****	****Feed By-Pass Protein & Essential AA.**
**8.****	****Use “N-Free” Essential AA (eg, MHA).**

## Milk Yield of Cows fed Forage as Alfalfa Silage or Alfalfa + Corn Silage Mixtures (Dhiman & Satter, 1998)

**	****	****	****	****Forage Source**
**Item****	****	****AS****	****2/3**** ****AS****:****1/3**** ****CS****	**** ****1/3**** ****AS****:****2/3**** ****CS**
_**Composition (% of DM)**_**	****	**

**	****Alfalfa Silage****	****50.0****	****33.3****	****16.7**
**	****Corn Silage****	****0.0****	****16.7****	****33.3**
**	****Conc. Mix****	****50.0****	****50.0****	****50.0**
**	****Crude Protein****	****18.6****	****17.5****	****16.6**
**	****NE****L**** (Mcal/kg DM)****	****1.69****	****1.69****	****1.69**
_**Production (kg/305 d)**_
**	****Milk (Multiparous)****	****9,570****.****b****	****10,160****.****a****	****10,020****.****ab**
**	****Ruminal NH****3**** (mM)****	****12.3****a****	****10.5****b****	****9.4****c**

## Approaches to Reducing Dietary CP

**1.****	****Accurate Tracking of Dietary CP Intake (MUN?).**
**2.****	****Feed Hay Rather Than Silage.**
**3.****	****Reduce NPN in Hay-Crop Silage.**
**4.****	****Dilute Hay-Crop Silage with Corn Silage.**
**5.****	****Feed More Concentrate (as Much as Possible?).**
**6.****	****Match CHO & CP Fermentation.**
**7.****	****Feed By-Pass Protein & Essential AA.**
**8.****	****Use “N-Free” Essential AA (eg, MHA).**

## Concentrate Supplementation of Alfalfa Silage & DM Intake & Milk Yield (Valadares et al., 2000)

## Approaches to Reducing Dietary CP

**1.****	****Accurate Tracking of Dietary CP Intake (MUN?).**
**2.****	****Feed Hay Rather Than Silage.**
**3.****	****Reduce NPN in Hay-Crop Silage.**
**4.****	****Dilute Hay-Crop Silage with Corn Silage.**
**5.****	****Feed More Concentrate (as Much as Possible?).**
**6.****	****Match CHO & CP Fermentation.**
**7.****	****Feed By-Pass Protein & Essential AA.**
**8.****	****Use “N-Free” Essential AA (eg, MHA).**

## Rumen NH3 & Production of Cows fed Alfalfa Silage& Ground HMEC (Ekinci & Broderick, 1997)

## Effect of Replacing Starch with Sugar

**	****	****	****	****	****Added Sugar**
**Variable****	****0.0%****	**** 2.5% ****	**** 5.0% ****	****7.5% ****	****Diet Prob.**
**	****DMI, kg/d****	****24.5****	****25.6****	****26.0****	****26.0****	****	****0.01**
**	****Milk, kg/d****	****38.9****	****40.4****	****40.0****	****39.4****	****	****0.74**
**	****FCM, kg/d****	****40.5****	****42.2****	****43.9****	****43.2****	****	**_**0.11**_
**	****Fat, %****	****3.81****	****3.82****	****4.07****	****4.16****	****	****0.01**
**	****Fat, kg/d****	****1.47****	****1.53****	****1.65****	****1.62****	****	****0.05**
**	****MUN****(as)****, mg/dl****	****11.0****	****10.3****	****10.8****	****10.3****	****	**_**0.12**_
**	****Rumen**** ****NH****3****N, mg/dl****	****6.9****	****6.8****	****6.2****	****5.8****	****	**_**0.14**_
**	****Rumen BCVFA, %****	****3.7****a****	****3.3****a****	****3.1****ab****	****2.4****b****	****	****0.02**
**	****	****	****	**** ****ab****(*****P***** < 0.05)**

## Approaches to Reducing Dietary CP

**1.****	****Accurate Tracking of Dietary CP Intake (MUN?).**
**2.****	****Feed Hay Rather Than Silage.**
**3.****	****Reduce NPN in Hay-Crop Silage.**
**4.****	****Dilute Hay-Crop Silage with Corn Silage.**
**5.****	****Feed More Concentrate (as Much as Possible?).**
**6.****	****Match CHO & CP Fermentation.**
**7.****	****Feed By-Pass Protein & Essential AA.**
**8.****	****Use “N-Free” Essential AA (eg, MHA).**

## Rumen-Protected (RP) Lys (40 g/d) & Met (15 g/d) & Milk Yield in Lactating Cows (Donkin et al., 1989)

**Milk Component****	****Control****	****RP-Lys + Met****	****Prob.****	**

**	****Milk (kg/day)****	****25.3****	****26.3****	****> 0.10**
**	****Protein (kg/day)****	****0.80****	****0.86****	****< 0.10**
**	****Protein (%)****	****3.15****	****3.25****	****< 0.01**
**	****Casein (%)****	****2.92****	****3.05****	****< 0.01**

## Variable Response with Rumen Protected Met + Lys

**1.****	**_**Piepenbrink et al. (1996):**_** ****No Improvement in Milk & Protein Yield.**
**2.****	**_**Armentano et al. (1997):**_** ****Improved Protein Yield (60g/d) w/ Met, Not Lys.**
**3.****	**_**Dinn et al. (1998).**_

## Dilution of Dietary CP w/ RP-AA (Dinn et al., 1998)

**Ingredient****	**** 15.3% CP ****	****16.7% CP ****	****18.3% CP**
**RP-Met, g/d****	****	****7.2****	****	****10.9****	****	****. . .**
**RP-Lys, g/d****	****	****7.5****	****	****6.0****	****	****. . .**
**	****DMI, kg/d****	****	****22.1****b****	****	****22.3****b****	****	****23.7****a**
**	****Milk yield, kg/d****	****	****32.8****b****	****	****32.8****b****	****	****34.2****a**
**	****Milk N, % N intake****	****	****33.1****a**** ****	****	****29.3****b****	****	****25.8****c**** **
**	****Urinary N, kg/d****	****	****0.162****c**** ****	****	****0.195****b****	****	****0.264****a**** **
**	****Fecal N, kg/d****	****	****0.151****	****	****0.155****	****	****0.158**
**(diets = 33% NDF)****	****	****	****abc****(P < 0.05)**

## Approaches to Reducing Dietary CP

**1.****	****Accurate Tracking of Dietary CP Intake (MUN?).**
**2.****	****Feed Hay Rather Than Silage.**
**3.****	****Reduce NPN in Hay-Crop Silage.**
**4.****	****Dilute Hay-Crop Silage with Corn Silage.**
**5.****	****Feed More Concentrate (as Much as Possible?).**
**6.****	****Match CHO & CP Fermentation.**
**7.****	****Feed By-Pass Protein & Essential AA.**
**8.****	****Use “N-Free” AA (eg, MHA; BC-VFA).**

## Liquid MHA (Alimet; “N-Free” AA)

**1.****	****Koenig et al. (1999): 50% MHA Escaped.****	**
**2.****	****Stephenson et al. (1990): Small Wool Growth Response w/ fed MHA (20% of Abomasal MHA).**
**3.****	****Future Use of RP-MHA or RP-AA C-Chains?**

## Feeding Branched-Chain VFA

**1.****	****Isobutyrate, Isovalerate, 2-Methyl Butyrate Used by Some Rumen Bacteria to Form BC-AA.**
**2.****	**_**Rogers et al. (1989):**_** BC-VFA Increased Milk Yield in Early Lactation on 43 Commercial Dairies.**
**3.****	**_**Otterby et al. (1990):**_** BC-VFA (0.8% of Diet) Increased Milk Yield in Mid- & Late-Lactation.**
**4.****	**_**Johnson et al. (1994):**_** No Effect of BC-VFA on Milk Yield (But a + Effect of RUP).**

## Feeding Less Total Crude Protein

**1.****	****Increase Profitability & **_**Reduce N-Pollution**_**.**
**2.****	****Produce “Better” Manure (eg, More Fecal-N).**
**3.****	****Protein Needed to Feed N to Rumen, EAA to Cow.**
**4.****	****Protein Needed to Optimize Feed Intake.**
**5.****	****16.5% CP**** Satisfactory; ****“Safety Margin”**** Problem.**
**6.****	****Can We Feed ****15% CP**** & Maintain Production?**