mal, so there is more opportunity for him to spread disease if he has some type of infection. “He will have more contact — cow to cow to cow. This is what we are see- ing with our current anaplasmosis study. “On one ranch we have a 25 per-
cent prevalence of carrier state in the cows, but 90 percent carrier state in the bulls. I’m thinking it may be because they have more contact with all the cows, but at this point we don’t really know. “I looked at the incidence of car- rier status on another ranch, out of
generally infects cattle at an early age if they are exposed to the patho- gens shed in manure from carrier cows. It takes years, however, before signs of the disease show up — with weight loss and diarrhea. A bull might be infected and you’d never know it, but he could introduce this devastating disease to your herd. “If you can buy bulls from herds
that are certifi ed Johne’s free, this is best,” says Gill. “It’s almost impossi- ble to test for this in young animals, such as a yearling or 2-year-old bull. They generally aren’t shed- ding the pathogen yet, until they
until he is many years older. So for some diseases we need to test as well as quarantine.” It’s wise to discuss this with your veterinarian before turning the bull out with the cows after a 3-week quarantine. “Some people fi gure they can
just test the bull for diseases, but for Johne’s this may not be ad- equate. Tests for Johne’s are not very reliable in the early stages of the disease — before clinical signs like weight loss (in spite of good appetite) and diarrhea appear. As the animal gets closer to the end stage, the test is also not very reli-
Always test a new bull for trich.
curiosity, and about 80 percent of the bulls were sero-positive com- pared to only about 30 to 40 percent of the cows. Again, there was higher prevalence in the bulls and we’re not sure why. Maybe the bulls were in a pasture with more ticks during the off-season,” he says. “If I am buying a bull, depending
on whether I’m in an area where anaplasmosis is prevalent or not, the bull’s status is something I’d want to know. If I brought an infected bull into a non-infected herd, this disease might be spread pretty fast — especially if there are vectors such as ticks or biting fl ies,” says Hairgrove. “Also, you don’t want to inadver-
tently add to this risk when working cattle. If the bull is part of the group when you are vaccinating and you don’t change needles, or if you are fl y-tagging without disinfecting the instrument between animals, you may spread the disease,” Hairgrove says.
Johne’s disease This is a serious disease that
102 The Cattleman October 2013
are 4 or 5 years old. A bull might be brought in with Johne’s and be sold (replaced with a younger bull) before he ever shows clinical signs of this disease. You might never know that he was the animal that brought this disease to your herd,” says Gill. If the bull has Johne’s and is
stressed during the breeding season he may start shedding the patho- gen. If you are buying any cattle, it’s important to know as much as possible about their background and have some faith in the breeder who raised them. People buy bulls from various sources and don’t always know much about the history of the herd of origin. The typical quarantine routine
for biosecurity won’t help in this situation. “When I ask producers what’s
the most important biosecurity fac- tor, they usually mention quaran- tine,” says Hairgrove. “I could keep a bull quarantined the rest of his life and he’s not going to show any signs of vibrio or trich, and may not show any signs of Johne’s either,
able. We can’t assume the test will tell us whether or not the animal has Johne’s.”
Bovine leukosis, leukemia, bluetongue “If a producer has a closed herd,
it’s worth the effort to try to keep out some of the diseases they don’t already have, and this might include bovine leukosis,” says Hairgrove. “Commercial producers might
not be too worried about this one, especially if they don’t know the status of their herds. Bovine leuko- sis is fairly common, but it’s some- thing you don’t want if you don’t already have it. When I brought bulls here to the vet school for the research project on trich, bovine leukosis was one of the things they had to be tested for to come here.” You could talk with your veteri- narian to discuss things like leuko-
Trichomoniasis is a costly disease. In Texas, bulls are required to be tested before they change ownership or possession, unless they are under a certain age.
thecattlemanmagazine.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134