Spring 2020 Newsletter

Reprinted from https://beef-cattle.extension.org/

Phosphorus, calcium, copper, cobalt, iodine, selenium, zinc, and manganese are all involved in governing successful reproduction. Since
mineral availability varies by region, consult your local county Cooperative Extension agent for more information regarding your area.

In formulating cow diets, one important mineral to consider that maintains normal reproductive function is phosphorus. Phosphorus supplementation
is important in most parts of the United States, but it becomes more important in areas of the country where cattle are maintained
on grazed forage year around. Thus, in areas of the country such as Arizona, New Mexico, Texas, and Oklahoma, phosphorus deficiency is
more likely to be observed than in parts of the country where cows are routinely maintained on summer grass and then fed harvested forage
during the winter months, both of which often contain adequate phosphorus. The phosphorus supplementation program you use should be
influenced by the phosphorus content of the forage being fed and the requirements of the cow.

The trace elements most likely to influence reproduction in cattle are copper, cobalt, iodine, selenium, zinc, and manganese, deficiencies of
which can occur in the grazing ruminant and affect reproductive performance or related important economic production parameters. Other
elements such as iron and molybdenum can be important considerations but seldom from a deficiency standpoint. In both cases, excesses can
have an impact on the animal, most notably by their negative impact on copper utilization.

Copper (Cu) is involved in numerous body physiological functions such as hemoglobin formation, iron absorption and mobilization, and
connective tissue metabolism—usually via copper’s involvement in enzyme function. In fact, one of the major effects of copper deficiency
may well be its effect on enzyme systems reducing productivity via alteration of enzymatic activity in the body. In a number of research
studies, it has been clearly documented that a copper deficiency can have an effect on fertility. This has been evidenced by a reduction in first
-service conception rates, altered embryonic survival (in situations of embryo transfer), and a reduction in overall pregnancy rates. The effect
on fertility can range from a very limited effect to a very pronounced decrease in first-service conception and overall pregnancy rates. It is
interesting to note that in a number of studies where copper deficiency has clearly been documented, there often is no impact on fertility or
any other reproductive parameter. In addition to its effect on fertility, research has shown that there will be an alteration in reproductive
behavior, or the manner in which cows show estrous activity. Specifically, cows may show normal estrous behavior and then in situations
where a severe copper deficiency develops, ovulation does not occur and, subsequently, there is a retardation of future estrous cycles. In
addition, there is evidence that copper can cause an alteration in semen quality in males. Exactly how does copper alter reproductive function
in animals? Some excellent research showed that the effect on reproduction may not relate to a copper deficiency but rather may relate to the
copper deficiency being created by excesses of other trace elements such as molybdenum and sulfur.

Considerable attention in the livestock industry is focused on trace element deficiencies such as copper, selenium, zinc, and other elements.
One of the hidden trace elements that may have considerably more influence than we realize is manganese.

As with copper, manganese probably exerts its greatest influence on the animal via its effect on enzyme systems. Research evidence exists
that manganese deficiencies can have an impact on suppression of conception rates, delayed estrus in both postpartum females and young
pre-pubertal heifers. In addition, there is excellent evidence that manganese deficiency will cause abortions in animals and deformed calves at
birth. There has been evidence that calves, at birth, will “knuckle over” at the fetlock. Other symptoms reported include poor calf growth and
loss of hair color in both calves and cows, and an increase in the incidence of cystic ovaries. The mode of action by which manganese causes
this deficiency is not clear other than it appears to be exerting these influences via enzyme systems in which it may be an essential co-factor.
There is strong evidence, for example, that the manganese content of ovaries in normal cows was considerably higher than in those with high
incidences of cystic ovaries. There is also excellent evidence that manganese, via its effect on enzymes systems, alters the synthesis of
gonadal steroids such as estrogen and progesterone in the female. Part of this explanation relates to the role of manganese in altering ovarian
luteal metabolism.

Selenium, an important trace element in many areas of the United States, can be both deficient and toxic even within the same state. Any
discussion of selenium also needs to include vitamin E. Although vitamin E will not be discussed to any extent in this article, there is
excellent evidence that the role of vitamin E in beef cow diets needs to be reevaluated, and it is very likely that in the future we will be using
higher levels of vitamin E supplementation in a beef cow diet. One manner in which a selenium deficiency can affect production in a cowherd
is an increase in the incidence of early embryonic death. In addition, another common clinical symptom associated with selenium deficiency
is an increase in the incidence of retained placentas with evidence in dairy herds of a selenium deficiency increasing incidence of retained
placenta from a level of 8 to 10 percent to 50 percent. Another effect of a selenium deficiency associated with reproductive functions is an
increased incidence of cystic ovaries and an increased incidence of weak or silent heat periods. Finally, evidence exists linking selenium
deficiency to weak calves at calving time.

Zinc, as with all trace elements, is actively involved in enzyme function. The role of zinc in reproductive function appears to be more pronounced on the male side than on the female side. Evidence exists in research studies that zinc deficiency in the bull causes impaired fertility, possibly associated with an alteration in the late-stage spermatozoa formation. This impairment of male fertility appears to be associated with the role of zinc as an activator of enzymes involved in the steroidogenesis process, which results in the secretion of testosterone and related hormones.

Logan grew up on a cow/calf and stocker operation near Neosho, Missouri. He attended Fort Scott Community College in Fort Scott, Kansas and then received his Bachelors at Missouri State in Springfield, Missouri. Shortly after college Logan took a position with a Co-op in Arkansas and later became a salesman for a feed company in that area. He currently lives in Tonganoxie, Kansas but will be relocating back to the Neosho, Missouri area in the near future.
His territory with MLS will include SW Missouri, NW Arkansas, SE Kansas and a portion of Northern Oklahoma.

He enjoys spending time with his family, hunting and anything that keeps him around the cattle business.