Case studies: Heifer development and reproductive failure (Proceedings)
Aug 01, 2010
CVC IN KANSAS CITY PROCEEDINGS
Heifer Breeding Model: Critical Control Points in Heifer Development
I. Weight per day of age at weaning, sire EPDs for milk production, growth, and calving ease/birthweight, and structural soundness (feet, legs, genetic defects)
Successful heifer development starts with selection of candidates for the replacement pool that are likely to reach puberty prior to the start of the breeding season, become pregnant early in the breeding season, have little calving difficulty, and re-breed early in the second breeding season. Because puberty is age and weight dependent, only heifers whose age and weight at weaning are compatible with being old enough and heavy enough prior to the start of breeding to reach puberty should be selected. Expected progeny differences for the sires and dams (when available) of individual heifers should be examined to find those heifers that are predicted to meet herd goals for mature size, growth rate, milking ability, and calving ease. Heifers with undesirable structural confirmation of feet and legs should not be included in the replacement pool, as well as heifers with a familiar history of genetic defects such as vaginal prolapse.
If subsequent CCPs have high failure rates, re-examining the selection criteria may be necessary to identify those traits most likely to be correlated with failure later in the heifer development system.
II. Vaccination protocol to enhance herd immunity to pregnancy-wasting diseases
For most beef herds, the potential list of diseases in a vaccination program would include: brucellosis, Infectious Bovine Rhinotracheitis (IBR), Bovine Viral Diarrhea (BVD), vibriosis (Campylobacteriosis), and leptospirosis. Other diseases for which vaccines are available include: Hemophilus somnus and trichomoniasis.
III. Body weight gain (ADG) during weaning to breeding period
Because weight is a primary factor determining the onset of puberty, ensuring that the nutritional program is meeting average daily gain requirements for the period from weaning to breeding is critical for a successful heifer development program. If weight gain is not as projected, the energy content of the diet can be increased so that target weight will be met. In addition, the use of ionophores, progestogens, and anthelmintics will help ensure that heifers reach target weights and puberty prior to the start of the breeding season.