Regular reproduction continues to be a challenge in dairy herds across the country. Researchers at the Animal Improvement Programs Laboratory of USDA have reported regional and national statistics on reproduction (Norman et al., 2009). Those statistics were obtained from DHI records from 1996 to 2007 for nearly 20 million AI breedings. Those breedings occurred during over 8 million lactations of over 5 million Holstein and Jersey cows in over 23,000 herds. Data reported were on days to first breeding (DFB) after calving, nonreturn rate at 70 days after breeding (NRR70) or the percentage of cows which did return to be serviced in 70 days, conception rate (CR), number of breedings per lactation (NB), breeding interval between first and last breeding (BI), days between calving and last breeding (DLB), and calving interval (CI). Statistics were summarized separately for Holsteins and Jerseys by breeding year and for Holsteins by seven regions of the United States. These data included herds of Holsteins, herds of Jerseys, and mixed herds of both breeds.

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Several changes in measures of reproduction are apparent in reviewing the statistics and are highlighted in the table below. First breedings after calving appear to be taking place sooner in recent years, as days to first breeding increased slightly from 1996 to 1999 for both breeds and then decreased until 2007. For Holsteins, DFB went from 92 up to 94 days and down to 85 days, whereas Jerseys went from 85 up to 88 days and then down to 83 days. Nonreturn rates at 70 days for first breedings after calving have decreased. In Holsteins, NRR70 decreased by 9 percentage units (54% to 45%), while in Jerseys it decreased 5 percentage units (from 57% to 52%). For all breedings, the decrease in NRR70 was 8 percentage units (from 52% to 44%) in Holsteins and 6 percentage units (from 54% to 48% for Jerseys). Conception rates declined by 2 percentage units for first services and by 3 percentage units for all services in Holsteins and by 3 percentage units for first services and 4 percentage units for all services in Jerseys. The number of breedings per lactation (NB) increased by 0.4 breedings in Holsteins and 0.3 breedings in Jerseys. This was accompanied by a lengthening of the breeding interval (BI) from first to last breeding in Holsteins of 18 days and in Jerseys by 11 days. Days from calving to last breeding (DLB) reflected the combined changes of decrease in days to first breeding and an increase in the number of breedings. The DLB increased 10 or 11 days from 1996 to 2006 for Jerseys and Holsteins, respectively. Overall calving interval (CI) increased 12 days in both breeds across 10 years which maintained a CI for Holsteins that was 12 days longer than for Jerseys in both 1996 and 2006. However, the calving intervals for Holsteins reached 428 days in 2001 before dropping back to 422 days in 2006 and reached 412 days in Jerseys in 2001 before dropping back to 410 days in 2006.

Breed	Breeding Year	DFB, d	NRR70, % 1st Breeding	NRR70, % All Breedings	CR, % 1st Breeding	CR, % All Breeding	NB, n	BI, d	DLB, d	CI, d
Holstein	1996	92	54	52	34	33	2.1	51	133	410
	2001	91	51	49	27	26	2.3	60	142	428
	2006	86	47	44	31	30	2.5	69	144	422
	2007	85	45	–	32	–	–	–	–	–
Jersey	1996	85	57	54	42	39	2.0	44	119	398
	2001	83	55	52	34	30	2.1	44	119	412
	2006	84	53	48	39	35	2.3	55	129	410
	2007	83	52	–	39	–	–	–	–	–
Adapted from Norman et al. DFB = days between calving and first breeding; NRR70 = nonreturn rate at 70 days after breeding; CR = conception rate; NB = number of breedings per lactation; BI = interval between first and last breeding; DLB = days between calving and last breeding; and CI = calving interval.

The effect of number of calvings or parity on these reproductive measures in the 2006 breeding year revealed Holsteins with more calvings having greater increases in DLB, longer CI, and more breedings (NB) than Jerseys with more calvings. The DLB went from 142 days for first lactation Holsteins to 156 for sixth or greater calvings, while the comparable figures for Jerseys were from 131 to 138. Calving interval was 12 days longer in second versus sixth or greater lactation Holsteins, while it was only 3 days longer in Jerseys of comparable parities.

Number of calvings and number of breeding effects were also apparent in comparisons of nonreturn rates at 70 days (NRR70). More calvings and more breedings resulted in greater decline in NRR70. In Holsteins, NRR70 declined from 48% in first breeding of first calvers to 45% for sixth or greater calvings, while Jerseys went from 53% to 51%. Jerseys showed a much greater decline in NRR70 percentage for second to fifth breedings with more calvings than did Holsteins. For Holsteins at third breeding, NRR70 was 43 for both first and sixth or greater calvings, while in Jerseys the NRR70 for the third breeding of first calvers was 49%, which declined to 41% for sixth and greater calvings. Fifth breeding of Holsteins for first calvers had an NRR70 of 39%, which increased to 40% by sixth and greater calvings, while NDD70 of fifth breedings of Jerseys declined from 42% for first calvers to 35% for sixth or greater calving. Conception rate (CR) declined for both Holsteins and Jerseys as more breedings took place in a lactation or as the number of calvings increased. Conception rate for first calf Jerseys was 40%, which declined to 28% by fifth breeding. For sixth or greater calvings, the CR of Jerseys was 33 and 25%, respectively. Holstein first calvers had a CR of 34% in first breeding, which declined to 26% in fifth breeding. For sixth or greater calvings, the CR at first breeding was 24% compared to 25% at fifth breeding. Intervals between breedings, from 2006 breedings, averaged 38.2 days for Holsteins and 35.5 days for Jerseys.

Holsteins and Jerseys have been compared in the same herd, with both breeds being in both a confinement and pasture feeding system (i.e., Holstein Confine, Holstein Pasture, Jersey Confine, and Jersey Pasture)(Washburn et al., 2002). This study showed no differences in the feeding systems, but Jerseys in both systems had statistically significantly higher percentages of cows inseminated (96.5 vs. 85.9%), conceiving when inseminated (59.6 vs. 49.5%), and pregnant in 75 days (78.1 vs. 57.9) than Holsteins.

Seven geographical regions were defined for the U.S. Holsteins for breedings in 2006: Mideast, Midwest, Mountain, Northeast, Northwest, Southeast, and Southwest. Regional differences were observed for all reproductive traits. The highest and lowest regions and the overall U.S. average are given in the table below. Overall, the Southwest region had the most desirable reproductive performance (e.g., lowest DFB, highest NRR70, highest CR percentage, lowest DLB, shortest CI, and highest Pregnancy Rate), and the Southeast had the least (lowest CR percentage, highest NB, longest CI, and a tie for lowest Pregnancy Rate). The inclusion of Daughter Pregnancy Rate in the genetic evaluations for Net Merit$ in 2003 has provided a genetic avenue to address reproduction issues and has an 11% relative value among all the traits in the index (Cole et al., 2010).

	DFB, d	NRR70, %	CR %, 1st Breeding	NB, n	DLB, d	CI, d	Pregnancy Rate, %
Highest	Mountain 92	Southwest 50	Southwest 33	Southeast 2.7	Mountain 157	Southeast 440	Southwest 28.3
Lowest	Southwest 84	Northwest 42	Southeast 26	Northeast 2.3	Southwest 127	Southwest 406	Southeast Mideast 22.2
U.S. average	86	47	31	2.5	144	422	24.9
Adapted from Norman et al. Pregnancy rate was calculated as 100(0.25)(233 – days open), with days open limited to 50 to 250 days.

Author Information

Jack McAllister
University of Kentucky

References

Cole, J.B., VanRaden, P.M. and Multi-State Project S-1040. 2010. Net Merit as a measure of lifetime profit: 2010 revision. Animal Improvement Programs. http://aipl.arsusda.gov/reference/nmcalc.htm

Norman, H.D., Wright, J.R., Hubbard, S.M., Miller, R.H. and Hutchinson, J.H. 2009. Reproductive status of Holstein and Jersey cows in the United States. J. Dairy Sci. 92:3517-3528.