| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Dairy Herd Analysis Service, Macdonald College of McGill University, 21,111 Lakeshore Road, Ste. Anne de Bellevue, PQ, Canada H9X 1C0, and Centre for Genetic Improvement of Livestock, Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada N1G 2W1
Individual cow test day records collected between December 1979 and June 1986 were used to generate 70, 90, and 305-d lactation yields of milk, fat, and protein for 11,457 Ayrshire and 112,371 Holstein cows in first lactation. Three separate analyses per breed were carried out according to a multiple-trait mixed model that included age and weight at calving with production traits for two of the three time periods. Sixty-six Ayrshire and 416 Holstein sires were treated as random in the analyses. Holsteins were on average younger and heavier at calving and averaged more milk per day than Ayrshires. Breed differences in daily fat and protein yield were small. Heritability estimates were higher for Holsteins than for Ayrshires for all traits, particularly 305-d production. Heritability of age at calving was very low. Weight at calving was more highly heritable than age but was less heritable than the production traits. Generally, phenotypic and genetic correlations between traits were very similar for Ayrshires and Holsteins. Phenotypically, both older cows and cows heavier at calving had higher yields of milk, fat, and protein. However, genetic correlations between weight at calving and production ranged from –.11 to –.30 and –.21 to –.38 in Holsteins and Ayrshires, respectively. Although not large, these correlations indicate that genetically heavier cows at first calving produce less milk, fat, and protein. Genetic and phenotypic correlations between yield traits were all positive and were .47 or greater. All genetic correlations between the same production trait measured for different lengths of lactation exceeded .90.
Key Words: age • weight • milk production
Submitted on April 17, 1990
Accepted on September 9, 1990
This article has been cited by other articles:
|
|
 |
|
  G. M. Haworth, W. P. Tranter, J. N. Chuck, Z. Cheng, and D. C. Wathes Relationships between age at first calving and first lactation milk yield, and lifetime productivity and longevity in dairy cows Vet Rec., May 17, 2008; 162(20): 643 - 647. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Svensson and J. Hultgren Associations Between Housing, Management, and Morbidity During Rearing and Subsequent First-Lactation Milk Production of Dairy Cows in Southwest Sweden J Dairy Sci, April 1, 2008; 91(4): 1510 - 1518. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Ruiz-Sanchez, R. W. Blake, H. M. A. Castro-Gamez, F. Sanchez, H. H. Montaldo, and H. Castillo-Juarez Short Communication: Changes in the Association Between Milk Yield and Age at First Calving in Holstein Cows with Herd Environment Level for Milk Yield J Dairy Sci, October 1, 2007; 90(10): 4830 - 4834. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. G. Cienfuegos-Rivas, R. W. Blake, P. A. Oltenacu, and H. Castillo-Juarez Fertility responses of Mexican Holstein cows to US sire selection. J Dairy Sci, July 1, 2006; 89(7): 2755 - 2760. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. A. Nilforooshan and M. A. Edriss Effect of Age at First Calving on Some Productive and Longevity Traits in Iranian Holsteins of the Isfahan Province J Dairy Sci, July 1, 2004; 87(7): 2130 - 2135. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
