sperm cell synthesis and develop- ment can take. “You really need to be sure that
the mineral is a well-designed min- eral, that it is covering all the bases, that it is good quality in terms of its availability, and it needs to match whatever the forage or pasture sys- tem that he is on,” he says. Blezinger says producers might
consider a “mineral audit,” assess- ing not only the content of their forage but that of the supplements they’re feeding. “That serves a twofold purpose,”
he says. “No. 1 is to make sure that you’re feeding the correct amount and to make sure it’s adequate. At the same time you want to make sure that it’s not excessive, because it’s very easy for a producer to go down to the local feed store, pick up a half dozen bags of mineral and that mineral not match your operation.”
He also advises producers to
test their water, particularly in the wake of the last couple of years of drought. “Pond levels are at pretty low levels in a lot of cases,” Blez- inger says. “When that water level decreases, we have all the particu- late matter in there. That increases the concentration and can in fact create a mineral imbalance.”
Signs of mineral imbalance There are some telltale signs
that can point to a mineral imbal- ance. Blezinger says a redness of the hair coat up around the shoulders and near the topline, especially on darker-haired animals like an An- gus type, could be indicative of a copper defi ciency. A dullness of the hair coat also
suggests either a copper or zinc shortfall. “Watch his mobility,” he suggests. “Is he walking smoothly? This is one of the things that you have to watch over a period of time to make sure that it’s not just some kind of a structural issue.” Other potential symptoms are tenderness in the feet, or stiffness in joints. You can pull a blood sample on a
suspect animal, Blezinger says, but it may not be reliable. “The problem we have with trace elements in the blood, or in the serum, is they’re transient,” he says. A test may show a normal reading for copper, but the animal stores copper and other trace minerals in his liver. A good blood reading on copper may mean that he’s mobilizing and depleting his liver stores. “By the same token, you can get
a false reading that indicates he may be defi cient just because of stress levels,” he says. “His blood levels may not be up where you would like for them to be, but if you were to do a liver biopsy, they would be just fi ne.”
94 The Cattleman October 2013
Minerals’ role in reproduction Blezinger says there are some
trace elements that do play a di- rect role in the bull’s ability to re- produce. Zinc and copper are involved
in the enzyme systems needed for the synthesis of sperm cells, he says. Dr. Jason Banta, professor and Texas A&M AgriLife Extension beef cattle specialist, says there are a lot of misconceptions about which minerals may affect bull fertility. “The one mineral that we have
researched and know impacts fer- tility in bulls is zinc,” he says. “It impacts testicular growth. If you have a zinc defi ciency it will actu- ally reduce growth and development of those testes in bulls.” Banta says there’s no evidence
in the literature that copper infl u- ences reproduction in bulls. Other than the need for zinc,
Banta says herd bulls are managed the same way nutritionally as are cows, although producers may need to make adjustments in the case of growing bulls. He says, “If producers are grow-
ing bulls at a high rate of gain of 3 to 5 pounds per day, which is higher than some people desire, they would defi nitely want to make sure they have plenty of calcium in the diet so we don’t impact skeletal development in those bulls.” Banta says the minerals that
garner the most attention are the “macrominerals” — calcium, phos- phorus, sodium, magnesium, potas- sium and sulfur. Among the trace minerals, the “big 3” are copper, zinc and selenium. Iodine, cobalt and iron also get consideration. He says, “Typically, bulls will
get the majority of the macrominer- als in their diet just from grazing forage — if the forages are grow-
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