Genome sequencing by University of Minnesota (UM) and USDA Agricultural Research Service (ARS) scientists was beneficial in developing new tests to rapidly detect and differentiate bacteria that cause Johne's disease in beef and dairy cattle.
Johne's disease, a M. paratuberculosis infection, causes chronic wasting in cattle and other ruminants. Using the genetic sequence of M. paratuberculosis, researchers are able to test and detect within 72 hours the microbe in animals' fecal samples. Previous tests took 6-18 weeks to process due to slow-growing bacteria.
The tests were developed by National Animal Disease Center (NADC) scientist Judith Stabel and Vivek Kapur, director of the UM Advanced Genetic Analysis Center.
Researchers hope the new tests, by identifying and isolating infected animals much sooner, will help curb animal-to-animal transmission and assist with better management practices of the disease.
— USDA ARS news release
Reproductive performance in young range cows is always a concern — moving these cows away from milk production to body weight gain has the potential to improve reproductive performance.
New Mexico State University (NMSU) researchers at the Corona Range and Livestock Research Center recently found cows fed a moderate level of glucose precursors were able to use nutrients for reproduction instead of putting all their energy into milk production.
The two-year study looked at altering nutrient partitioning to help these young cows' reproductive performance. From February-July 2003 (n=51) and 2004 (n=40), researchers evaluated the response of 2- and 3-year-old postpartum beef cows grazing dormant native range using three protein supplements.
The supplements were fed twice weekly at a rate of 2.5/lbs./cow/day for about 69 days postpartum. The supplements were 30% crude protein and contained wheat middlings, cottonseed meal and feather meal, with increasing proportions — 0 (UIP0), 80 (UIP80) or 160 (UIP160) g/day — of propionate salt. The supplements also contained minerals and vitamin A.
Feed costs for the supplementation period were $21.09, $30.27 and $39.89/cow, respectively. When combining this study with a previous two-year study where similar supplements were fed, researchers averaged across all four years that the cows fed the UIP80 supplement produced less milk — 14.6 vs. 16.3 lbs./day for UIP80 and UIP0, respectively — and cycled earlier — 89 days vs. 98 days postpartum for UIP80 and UIP0, respectively.
Pregnancy rates averaged, across the four years, 91.4% for cows fed UIP0 and 93.1% for cows fed UIP80. And, even though feed costs were higher for the UIP80 cows, their calves had the potential to be heavier at weaning because they bred back faster than cows fed UIP0, resulting in increased income of $19.82/cow.
— Endecott et al., NMSU 2005 Cattle
Grower's Short Course Proceedings & Livestock Research Briefs
Researchers at Montana State University (MSU) found no significant difference in reproductive traits and calf performance in first-calf heifers on western range selected for lean meat yield or higher quality grade.
The researchers evaluated the impact of selecting for high marbling or high retail product yield on reproductive traits and calf performance of first-calf heifers on western range cattle. The study was conducted over a three-year period.
Mature Angus cows were artificially inseminated (AI) to Angus bulls with either high marbling (MB) or high retail product (RP) EPDs. Data was analyzed on 133 MB and 121 RP first-calf heifers and 156 calves. Researchers looked at: 1) total pregnancy using AI and natural service of heifers as yearlings; 2) rebreeding pregnancy rates of 2-year-olds; 3) prebreeding cow body weight; and 4) weaning weight of first calves.
They concluded that selecting for lean meat yield or higher quality grade should not have a negative influence on reproduction of replacement females (Davis et al. 2005. Pro. Western Section ASAS. 56:102).
— Michigan State University Fall 2005
Beef Cattle Research Update
Beef tenderness is critical to the palatability of a steak. But, it's difficult to obtain tenderness data on an animal before harvest, and to select for this trait. Because of this, selection for genetic improvement of tenderness hasn't been a main criteria in most genetic programs.
But in the era of DNA marker-assisted selection (MAS) tools, MAS has the potential to improve traits, like beef tenderness, for which selection historically has been difficult. The current challenge is to find markers in these traits that will be useful in many populations.
ARS scientists at the USDA Meat Animal Research Center in Clay Center, NE, studied the markers in CAPN1, which encodes the enzyme µ-calpain — thought to be one of the most important enzymes in beef tenderness.
Three objectives were studied: 1) to test for the existence of beef tenderness markers in the CAPN1 gene segregating in Brahman cattle; 2) test existing CAPN1 tenderness markers in indicus-influenced crossbred cattle; and 3) produce a revised marker system for use in cattle of all subspecies backgrounds.
Two markers have been identified for use in Bos taurus-type cattle (markers 316 and 530), but neither marker has been shown to work well with Brahman-based cattle.
Researchers were able to identify a third marker in the CAPN1 gene — marker 4751 — associated with meat tenderness in Brahman cattle. The new marker was also tested and associated with tenderness in Bos taurus cattle, as well as crossbred cattle. This indicates that one marker could have wide applicability in cattle of all subspecies backgrounds.
ARS researchers say these results expand possibilities for commercial herds to use genetic markers to improve meat tenderness — especially in herds using Brahmans and/or crossbreds.
— White et al. 2005.
Journal of Animal Science, 83:2001