|Perry, George -|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: May 17, 2013
Publication Date: N/A
Technical Abstract: Calving late as a heifer has long been reported to increase the chance of calving late or not calving the following year, and heifers that calve early tend to remain in those calving groups throughout their life. According to a review by Patterson and co-workers, heifers need to calve by 24 months of age to achieve maximum life-time productivity. Furthermore, heifers that lose a pregnancy or conceive late in the breeding season are likely to not have enough time to rebreed during the subsequent defined breeding season, and any cow that misses a single calving is not likely to recover the lost revenue of that missed calf. A cow needs to wean 3 to 5 calves to pay for her development costs. Therefore, longevity of a beef female is important to the sustainability and profitability of any beef operation. Considering the importance of longevity, an important question is as follows: Why are females culled from a beef herd? According to the 2007-08 NAHMS survey the greatest percentage of cows culled from the herd were for pregnancy status (33.0%); other reasons for culling included age or bad teeth (32.1%), economic reasons (14.6%), other reproductive problems (3.9%), producing poor calves (3.6%), temperament (3.6%), injury (2.9%), udder problems (2.7%), bad eyes (1.8%), and other problems (1.8%). Furthermore, 15.6% of cows (animals that have previously calved) culled were less than 5 years of age and 31.8% were 5 to 9 years of age. These females that are culled from a herd prior to producing 5 calves increase the developmental cost of other heifers and do not contribute to the profitability and sustainability of the operation. Therefore, understanding how puberty and conception date can impact pregnancy success and longevity can have a tremendous impact on the profitability and sustainability of an operation.