# Presentation: 254917

## Responses to alternative genetic choices in dairy grazing systems

**	**

**	**

## Phenotypic trend in days open

**Lactation**

## Benefits of improved reproduction

**Lower semen cost **
**Improved ability to optimize lactation and lifetime yields **
**Reduced culling due to delayed or failed conception**
**More herd replacements**

## Bull fertility evaluations

**Estimated Relative Conception Rate (ERCR)**
**70-day nonreturn rate (NRR) Source:**
**DRMS (Raleigh, NC), 1986−2005**
**USDA (Beltsville, MD), 2006−present**
**Western Bull Fertility Analysis**
**75-d veterinary-confirmed conception rate **
**Source: AgriTech (Visalia, CA), 2003 −present**

## ERCR distribution (Aug. 2007)

## New service sire evaluation coming

**Based on conception rate rather than NRR**
**More accurate**
**Inseminations from most of the United States**
**All services (not just first)**
**Additional model effects included**
**Available in Spring 2008 **
**Documentation at ****ftp://aipl.arsusda.gov/pub/outgoing/BullFert/**

## Pregnancy rate (PR)

**Percentage of nonpregnant cows between 50 and 250 days in milk that become pregnant during each 21-day period**
**Advantages over days open (DO), the days from calving to conception**
**Easily defined**
**Information from nonpregnant cows included more easily**
**Larger (rather than smaller) values desirable**

## PR (continued)

**PR = [21/(DO − VWP + 11)]100**
**Voluntary waiting period (VWP) assumed**
**	****to be 60 days**
**Factor of +11 adjusts to middle day of**
**	****21-day cycle**
***Examples***
**Herd with average of 133 DO has PR of 25%**
**Herd with average  of 154 DO has PR of 20%**

## USDA pregnancy rate

**Linear approximation**
**PR = 0.25 (233 − DO)**
**1% higher PR = 4 days fewer open**

## Current breed averages

| Breed | PR (%) | DO (d) | Gestation length (d) | Calving interval (d) |
| --- | --- | --- | --- | --- |
| Ayrshire | 23.2 | 140 |  282 | 422 |
| Brown Swiss | 20.3 | 152 |  288 | 440 |
| Guernsey | 19.1 | 157 |  286 | 443 |
| Holstein | 22.0 | 145 |  280 | 425 |
| Jersey | 26.4 | 127 |  280 | 407 |
| Milking
   Shorthorn | 24.8 | 134 |  281 | 415 |

## Daughter pregnancy rate (DPR)

**First USDA genetic evaluations in 2003**
**Same across-breed animal model as for yield traits, productive life (PL), and somatic cell score (SCS)**
**Heritability of 4%**

## DPR (continued)

**Predicted transmitting abilities (PTAs) reported as percentages**
**Daughters of bull with PTA DPR of 1 expected to be 1% more likely to become pregnant during estrous cycle than if bull had PTA DPR of 0 **
**Each increase of 1% in PTA DPR equals a decrease of 4 days in PTA DO**
**PTA DO approximated by −4 ****× ****PTA DPR**
***Example:***** Bull with PTA DPR of +2.0 would have PTA DO of −8**

## Phenotypic trend in days open

**Lactation**

## DPR trend (August 2007 base)

## Bull PTA DPR frequency (Aug. 2007)

## Application of selection indexesfor dairy producers

**H.D. Norman**

**Missouri Dairy Summit (****)**

**Application of ****selection indexes****for dairy producers**

## Lifetime merit indexes

| Trait | Units | Relative value (%) |  |  |
| --- | --- | --- | --- | --- |
|  |  | Net
merit | Cheese 
merit | Fluid
merit |
| Protein | Pounds | 23 | 28 | 0 |
| Fat  | Pounds | 23 | 18 | 23 |
| Milk | Pounds | 0 | −12 | 24 |
| PL | Months | 17 | 13 | 17 |
| SCS | Log | −9 | −7 | −9 |
| Udder | Composite | 6 | 5 | 6 |
| Feet/legs | Composite | 3 | 3 | 3 |
| Body size | Composite | −4 | −3 | −4 |
| DPR | Percent | 9 | 7 | 8 |
| Calving ability | Dollars | 6 | 4 | 6 |

## Genetic merit of high-DPR Holstein bulls

| Trait | All active
AI bulls | Active AI
bulls with
PTA DPR
of ≥2.0 % | Top 50% of active AI bulls based on lifetime net merit
(>$245) | Top 50% of active AI bulls
with PTA DPR of ≥2.0% based on
PTA DPR
(>2.3 %) |
| --- | --- | --- | --- | --- |
| Bulls (no.) | 684 |  |  |  |
| PTA milk (lb) | 838 |  |  |  |
| PTA fat (lb) | 32 |  |  |  |
| PTA protein (lb) | 25 |  |  |  |
| PTA SCS | 2.94
 |  |  |  |
| PTA PL (mo) | 1.1 |  |  |  |
| PTA DPR (%) | −0.4 |  |  |  |
| PTA DO (derived) | 1.6 |  |  |  |
| Net merit ($) | 242 |  |  |  |
| Semen price ($/unit) | 24 |  |  |  |

## Genetic merit of high-DPR Holstein bulls

| Trait | All active
AI bulls | Active AI
bulls with
PTA DPR
of ≥2.0 % | Top 50% of active AI bulls based on lifetime net merit
(>$245) | Top 50% of active AI bulls
with PTA DPR of ≥2.0% based on
PTA DPR
(>2.3 %) |
| --- | --- | --- | --- | --- |
| Bulls (no.) | 684 | 41 |  |  |
| PTA milk (lb) | 838 | 287 |  |  |
| PTA fat (lb) | 32 | 14 |  |  |
| PTA protein (lb) | 25 | 17 |  |  |
| PTA SCS | 2.94 | 2.86
 |  |  |
| PTA PL (mo) | 1.1 | 4.2 |  |  |
| PTA DPR (%) | −0.4 | 2.5 |  |  |
| PTA DO (derived) | 1.6 | −10.0 |  |  |
| Net merit ($) | 242 | 346 |  |  |
| Semen price ($/unit) | 24 | 25 |  |  |

## Genetic merit of high-DPR Holstein bulls

| Trait | All active
AI bulls | Active AI
bulls with
PTA DPR
of ≥2.0 % | Top 50% of active AI bulls based on lifetime net merit
(>$245) | Top 50% of active AI bulls
with PTA DPR of ≥2.0% based on
PTA DPR
(>2.3 %) |
| --- | --- | --- | --- | --- |
| Bulls (no.) | 684 | 41 | 342 |  |
| PTA milk (lb) | 838 | 287 | 1,125 |  |
| PTA fat (lb) | 32 | 14 | 43 |  |
| PTA protein (lb) | 25 | 17 | 34 |  |
| PTA SCS | 2.94 | 2.86 | 2.88
 |  |
| PTA PL (mo) | 1.1 | 4.2 | 2.1 |  |
| PTA DPR (%) | −0.4 | 2.5 | −0.1 |  |
| PTA DO (derived) | 1.6 | −10.0 | 0.4 |  |
| Net merit ($) | 242 | 346 | 357 |  |
| Semen price ($/unit) | 24 | 25 | 25 |  |

## Genetic merit of high-DPR Holstein bulls

| Trait | All active
AI bulls | Active AI
bulls with
PTA DPR
of ≥2.0 % | Top 50% of active AI bulls based on lifetime net merit
(>$245) | Top 50% of active AI bulls
with PTA DPR of ≥2.0% based on
PTA DPR
(>2.3 %) |
| --- | --- | --- | --- | --- |
| Bulls (no.) | 684 | 41 | 342 | 20 |
| PTA milk (lb) | 838 | 287 | 1,125 | 179 |
| PTA fat (lb) | 32 | 14 | 43 | 13 |
| PTA protein (lb) | 25 | 17 | 34 | 16 |
| PTA SCS | 2.94 | 2.86 | 2.88 | 2.84
 |
| PTA PL (mo) | 1.1 | 4.2 | 2.1 | 4.4 |
| PTA DPR (%) | −0.4 | 2.5 | −0.1 | 2.9 |
| PTA DO (derived) | 1.6 | −10.0 | 0.4 | −11.6 |
| Net merit ($) | 242 | 346 | 357 | 350 |
| Semen price ($/unit) | 24 | 25 | 25 | 21 |

## Genetic merit of high-DPR Holstein bulls

| Trait | All active
AI bulls | Active AI
bulls with
PTA DPR
of ≥2.0 % | Top 50% of active AI bulls based on lifetime net merit
(>$245) | Top 50% of active AI bulls
with PTA DPR of ≥2.0% based on
lifetime net merit (>$386) |
| --- | --- | --- | --- | --- |
| Bulls (no.) | 684 | 41 | 342 | 20 |
| PTA milk (lb) | 838 | 287 | 1,125 | 735 |
| PTA fat (lb) | 32 | 14 | 43 | 31 |
| PTA protein (lb) | 25 | 17 | 34 | 30 |
| PTA SCS | 2.94 | 2.86 | 2.88 | 2.84
 |
| PTA PL (mo) | 1.1 | 4.2 | 2.1 | 5.1 |
| PTA DPR (%) | −0.4 | 2.5 | −0.1 | 2.6 |
| PTA DO (derived) | 1.6 | −10.0 | 0.4 | −10.4 |
| Net merit ($) | 242 | 346 | 357 | 476 |
| Semen price ($/unit) | 24 | 25 | 25 | 26 |

## DPR benefits to herd

**Decreased units of semen needed per pregnancy**
**Decreased labor and supplies for heat detection, inseminations, and pregnancy checks**
**Additional calves produced**
**Higher yields because more ideal lactation lengths**

## Lifetime value

**Factors in determining economic value to DPR**
**Loss of about $1.50/DO**
**2.8 lactations per cow**
**No breedings for half of cows during final lactation**
**Correlation of heifer and cow fertility (0.3)**
**Value of extra calves**
**Other unmeasured health expenses**
**Total lifetime merit value of $21/PTA DPR unit**

## What genetic programs work well for U.S. graziers?

## Grazier breeding

**Objective**
**Cattle with better fertility or other desired characteristics**
**Approaches (occasional use)**
**Bulls from countries that practice grazing**
**Bull breed different from cow breed to capitalize on heterosis**
**Effectiveness in grazing herds?**

## Genetic alternative

**To achieve top fertility, consider direct selection for daughter fertility**
**U.S. bulls with high DPR**
**High fertility bulls from all sources**

## Comparison study

**Daughter performance within U.S. herds**
**New Zealand AI Holstein/Friesian bulls**
**Other AI Holstein bulls (predominantly U.S.)**
**Cows included**
**DHI records in AIPL national database**
**Calved (1st parity) before December 2006**
**Time to express the performance traits**

## Traits examined

**Milk, fat, protein**
**Somatic cell score**
**Days open**
**Conformation traits**

## Yield and SCS data 

**First-lactation daughters (239 herds)**
**896 sired by 40 New Zealand bulls**
**13,251 sired by 1,888 U.S. bulls**
**Second-lactation daughters (211 herds)**
**680 sired by 34 New Zealand bulls**
**10,927 sired by 2,283 U.S. bulls**
**Third-lactation daughters (181 herds) **
**453 sired by 29 New Zealand bulls**
**7,403 sired by 1,784 U.S. bulls**

## Yield results

**Milk ****	****U.S. daughter superiority**
**First lactation****	****   983 lb*****
**Second lactation****	****1,115 lb*****
**Third lactation****	****   772 lb*****
**Fat****	****New Zealand daughter superiority/advantage**
**First lactation****	****   10 lb****
**Second lactation ****	****  4 lb**
**Third lactation****	****11 lb**
**Protein****	****U.S. daughter superiority/advantage**
**First lactation****	****     10 lb*****
**Second lactation****	****     12 lb*** **
**Third lactation****	****  5 lb  **

## Economic value

**Current U.S. milk prices**
**MFP$ = ****	****0.016****	******** milk****	****+ **
** ****	****	****1.50 ****	******** fat ****	****+**
** ****	****	****1.95 ****	******** protein **
**U.S. daughter MFP$ superiority**
**First lactation****	****$20.76**
**Second lactation****	****$34.80**
**Third lactation****	****  ****$6.21**

## SCS results

**First lactation**
**U.S. daughter superiority of 0.15*****
**Second lactation**
**U.S. daughter advantage of 0.09**
**Third lactation**
**New Zealand daughter advantage of 0.05**

## DO data 

**First-lactation daughters (219 herds)**
**816 sired by 38 New Zealand bulls**
**9,747 sired by 2,113 U.S. bulls**
**Second-lactation daughters (189 herds)**
**614 sired by 33 New Zealand bulls**
**9,747 sired by 2,113 U.S. bulls**
**Third-lactation daughters (161 herds) **
**392 sired by 28 New Zealand bulls**
**6,561 sired by 1,637 U.S. bulls**

## DO results

**First lactation**
**New Zealand daughter superiority of 8 days****
**Second lactation**
**New Zealand daughter superiority of 7 days****
**Third lactation**
**New Zealand daughter advantage of 2 days**

## Type data 

**First-lactation daughters**
**100 sired by 14 New Zealand bulls**
**376 sired by 225 U.S. bulls**

## Type results

**Final score**
**U.S. daughter superiority of 1.5 points***
**Strength**
**N.Z. daughter scored higher by 1.9 points***
**Rear legs**
**U.S. daughter scored higher by 2.4 points***
**Foot angle**
**N.Z. daughter scored higher by 1.7 points***

## Type results (continued)

**Body condition**
**N.Z. daughter scored higher by 2.3 points***
**Rear udder height**
**U.S. daughter superiority of 1.8 points***
**Udder depth**
**U.S. daughter scored higher by 3.3 points*****
**Teat placement**
**U.S. daughter scored higher by 2.3 points***

## Spring-calver subset

**In addition to studying all herds using New Zealand bulls, a “grazing” subset was defined by seasonal calving**
**Number of March****–****May calvings more than 3 times number of September****–****November calvings for at least 3 of 5 years during 2002****–****06**
**At least 25 reported calvings per year**

## Spring-calver data 

**First-lactation daughters (18 herds)**
**222 sired by 18 New Zealand bulls**
**2,536 sired by 203 U.S. bulls**
**Second-lactation daughters (23 herds)**
**153 sired by 16 New Zealand bulls**
**1,845 sired by 243 U.S. bulls**
**Third-lactation daughters (14 herds) **
**97 sired by 13 New Zealand bulls**
**1,043 sired by 13 U.S. bulls**

## Spring-calver yield results

**Milk ****	****U.S. daughter superiority**
**First lactation****	****   762 lb*****
**Second lactation****	****1,102 lb*****
**Third lactation****	****1,064 lb*****
**Fat****	****New Zealand daughter advantage**
**First lactation****	**** 11 lb **
**Second lactation ****	****   5 lb**
**Third lactation****	****   5 lb**
**Protein****	****U.S. daughter superiority/advantage**
**First lactation****	**** 11 lb***
**Second lactation****	**** 16 lb* **
**Third lactation****	****12 lb  **

## Spring-calver SCS results

**First lactation**
**U.S. daughter superiority of 0.24****
**Second lactation**
**U.S. daughter advantage of 0.12**
**Third lactation**
**U.S. daughter advantage of 0.17**

## Spring-calver DO results

**First lactation**
**U.S. daughter advantage of 4 days**
**Second lactation**
**New Zealand daughter advantage of 3 days**
**Third lactation**
**Days open averaged the same for both**

## Conclusions

**H.D. Norman**

**Missouri Dairy Summit (****)**

**Conclusions**

## Conclusions

**Strain differences between U.S. Holsteins and New Zealand Friesians for several traits**
**Higher milk and protein yields for U.S. bull daughters; higher fat yield in 1st lactation for New Zealand bull daughters**
**Superior 1st-lactation SCS for U.S. bull daughters**

## Conclusions (continued)

**Fewer 1st- and 2nd-lactation DO for New Zealand bull daughters**
**Higher strength and body condition score for New Zealand bull daughters**
**Better rear udder height, udder depth, and teat placement for U.S. bull daughters**

## Caution

**Strain differences observed influenced by individual bulls chosen from each country**
**Slightly greater selection intensity for New Zealand bulls than for U.S. bulls**

## Recommendations to breeders 

**Usual Recommendation: Don’t select bulls solely on one trait because many traits have economic value **
**Consider economic value of all performance traits in your own market when making genetic choices**
**Dairies with seasonal calving should find an index that puts more weight on daughter fertility than those recommended for the general industry**

## Selection for bull fertility

**Breeding to bulls with higher conception rates returns a profit fairly quickly**
**Premium of $2 could be paid for semen per 1% improvement in fertility**
**Thus, a unit of semen from bull with ERCR of +2 is worth $8 more than a unit from bull with ERCR of −2**
**Use bull fertility as a secondary selection trait after picking bulls on their economic indexes**

## Selection for cow fertility

**Selection for improved fertility will pay off, even though the benefit is delayed for 2 years**
**Choose your sires based on lifetime economic merit that includes daughter fertility, rather than for daughter fertility alone**
**However, producers with herd fertility problems could emphasize DPR extensively with little loss in overall net merit**

## Fertility emphasis

**Service-sire fertility and DPR especially important for grazing herds with seasonal calving**
**Use of a few bulls that average 3.0% for PTA DPR (equivalent to a decrease of 12 DO) could neutralize   r much of genetic decline in fertility from use of high-yield bulls for 40 years**
**Select for overall merit based on genetic-economic index appropriate for your situation and milk market **

## Thank you!

***Thank you!***