Submitted to: Mid-Atlantic Dairy Grazing Conference
Publication Type: Proceedings
Publication Acceptance Date: 10/24/2006
Publication Date: 10/31/2006
Citation: Norman, H.D., Wright, J.R., Powell, R.L. 2006. Is there a need for different genetics in dairy grazing systems?. Proceeding of 6th Mid-Atlantic Dairy Grazing Conference, October 31 - November 1, Goldsboro, North Carolina, p. 1-5. Interpretive Summary:
Technical Abstract: The decline in cow fertility has had a negative impact on all dairy producers, especially those that practise seasonal calving with pasture-based dairying. One alternative that is being tried in the United States by a few graziers who are interested in improved fertility is to use bulls from New Zealand because New Zealand producers have practised grazing and seasonal calving for many years. A study was initiated to compare the performance of daughters of Holstein bulls from New Zealand with daughters of other Holstein bulls (predominantly from the United States). Daughters of U.S. bulls had higher milk and protein yields than daughters of New Zealand bulls, but fertility was improved by the use of New Zealand semen. An alternative to using bulls only from countries that practice grazing is to select for improved reproduction from the best sources available. Producers should consider the economic values of all performance traits, and those should be combined into an index appropriate for expected economic conditions. Producers who practice grazing with seasonal calving should place more weight on fertility traits than is recommended for the general dairy cattle industry because of their higher economic value in a grazing environment. Selection of bulls with superior daughter fertility combined with good reproductive management can help to eliminate the disappointing fertility that producers have lived with in the past.