# Presentation: 132534

## Performance of Holsteins that originated from embryo transfer or twin births

*H.D. Norman, J.R. Wright*** **and R.L. Powell *
- Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350

- OBJECTIVES
- Compare the performance of ET Holsteins to their non-ET full sibs.
- Compare cows from multiple births (twins, triplets) to their single birth full sibs.

- INTRODUCTION
- Preferential management of embryo transfer  (ET) animals could potentially cause bias in genetic evaluations.
- Previous studies have indicated that the rate of twin births may be increasing.

- CONCLUSIONS
- Numbers of ET animals peaked in 1993 and is currently declining.
- Numbers of cows coded twin (multiple birth) has increased during the last 25 years.
- PA of ET cows and bulls was superior to the population mean for milk, fat and protein.
- PA of bulls coded twin (multiple birth) was less than population mean while PA of cows was nearly the same.
- ET cows were nearly identical to their non-ET full sisters for all traits indicating no preferential treatment.
- Cows coded twin were out-performed by their non-twin full sibs and stayed in the herd for an average of .4 mo less.

- DATA
- ET
- 293,033 females and 129,394 males with pedigree records.
- 185,104 cows and 26,238 bulls with Parent Average (PA) records.
- 10,277 cows and 3,512 bulls with PTAs also having non-ET full sibs with PTAs.
- Twin (all multiple births; twins, triplets)
- 684,329 multiple birth code females with pedigree records and 11,446 multiple birth code males with pedigree records.
- 301,434 multiple birth code cows and 769 multiple birth code bulls with PA records.
- 6,514 multiple birth code cows and 57 multiple birth code bulls with PTAs also having full sibs with PTAs.

- RESULTS *(cont.)*

- RESULTS

- Abstr.W89

- PA of ET cows was superior to cow population mean by an average of 133 kg for milk.
- PA of ET bulls was superior to cow population mean by an average of 339 kg  and bull population mean by 80 kg for milk.

- 						ET		Full Sisters
**Standardized trait:**
- 	Milk (kg)			     10,570		     10,565
- 	Fat (kg)		    	         387		        390
- 	Protein (kg)		         315		         316
- 	SCS				            3.1			    3.1
- 	Productive Life (mo)		 26.9			  26.3
**Yield deviation:**
- 	Milk (kg)			        -287			-277
- 	Fat (kg)			           -6			   -3
- 	Protein (kg)			   -6			   -5
**PTA:**
- 	Milk (kg)				 -106			 -107
- 	Fat (kg)				    -2			    -1
- 	Protein (kg)			    -2			    -2
- 	SCS					     3.1		     3.1	Productive Life (mo)		     0.3		     0.3

- PA of cows recorded from twin births was nearly identical to the population mean with a difference of only 3 kg for milk.
- PA of bulls recorded from twin births was less than bull population mean by an average of 138 kg for milk.

- 				     	     Twins		Full Sisters
**Standardized trait:**
- 	Milk (kg)			     10,050		     10,161
- 	Fat (kg)		    	         366		        371
- 	Protein (kg)		         298		         301
- 	SCS				            3.1			    3.1
- 	Productive Life (mo)		 26.3			  26.7
**Yield deviation:**
- 	Milk (kg)			        -500			-407
- 	Fat (kg)			          -17			  -12
- 	Protein (kg)			  -14			   -11
**PTA:**
- 	Milk (kg)				 -186			 -170
- 	Fat (kg)				    -6			    -5
- 	Protein (kg)			    -2			    -2
- 	SCS					     3.1		     3.1
- 	Productive Life (mo)		     0.0		    0.0

- Productive Life was .6 mo longer for ETs than for their non-ET full sib sisters.
- PTAs for ETs and their non-ET full sib sisters were nearly identical.

- Yield deviations of twin cows were lower than their non-twin full sibs by 93, 5, and 3 kg for milk, fat, and protein, respectively.
- Average PTAs of twin cows were lower than their non-twin full sibs for milk and fat but the same for protein, SCS, and PL.

**Means for Holstein ET cows with DHI milk records and their non-ET full sisters**

**Means for Holstein twin cows with DHI milk records and their non-twin full sisters**

- RESULTS