Building a strong foundation in the cow herd, heifer development or purebred program starts with genetics but can also be affected by management and nutrition. Reproductive failures are often tied to suboptimal nutrition and can impact not only the individual animal but their offspring’s well-being too. This is referred to as maternal or fetal programming and pertains to the impact of nutritional and health status of the mother during pregnancy and the subsequent impact on health and productivity of her calf.
Fetal programming
Maternal nutrition can impact the fetus and potentially alter development, not just in utero but later in life as well. Compromised nutrition during gestation can result in low birthweight, increased pre-weaning mortalities and poor growth rates. When we talk about maternal nutrition, the focus has traditionally been on the last trimester of gestation, since this is the time period when the fetus grows more rapidly, taxing the cow’s energy and mineral reserves. Therefore, we see most nutritional strategies built around that 90 or even 60 days prior to calving. But what about the impact of maternal nutrition during early and midgestation?
A recent publication discussed the importance of proper nutrition throughout all phases of gestation and the impact nutrition can have beyond just looking at pregnancy percentages. In another study where early gestation cows were fed either 100% or 55% of their nutrient requirements, there were no differences between calf bodyweight and gain, but lung and trachea weights of calves born to nutrient-restricted dams were significantly less, which can potentially impact how these calves would react to respiratory challenges. Nutrient restriction during midgestation has also been shown to impact ovary and luteal tissue size and mass, which can directly impact the heifer’s reproductive efficiency later in life. Nutritional status of the cow during late gestation (six to nine months) has shown to impact calf muscle fiber formation, which can impact birthweight, weaning weight and even carcass weight at harvest.
Reproductive performance in ruminants is highly dependent on their nutritional status. Trace minerals, especially, are involved in the synthesis of reproductive hormones, reduction of free radicals, improvement of the uterine microenvironment for embryonic implantation, and fetal growth and development. Considering that reproductive organs develop for the most part during early gestation, it is easy to see just how much of an impact the dam’s nutritional and especially trace mineral status can have on fetal development and future performance.
Need for trace mineral supplementation
Feeds and forages vary in trace mineral concentration. (Variations exist among species and seasonally.) Supplemental copper, zinc, manganese and selenium are needed to optimize the herd’s trace mineral status, which is fundamental for immunity, health, reproductive efficiency and growth. Supplemental trace minerals are thus provided to bridge the gap between the amount available through forages and the cow’s nutritional requirements, but forms of trace minerals (inorganic or organic) used to supplement with can have a significant impact on how the herd responds to the chosen trace mineral program.
Inorganic versus organic
Inorganic trace minerals (including sulfates, oxides, chlorides and hydroxies) are typically inexpensive byproducts of other industrial processes and often fed in excess to avoid deficiencies. However, with lower relative bioavailability, animals do not necessarily benefit from oversupplementation, and these high levels of inorganic trace minerals are often linked to mineral-to-mineral antagonisms (which can lead to mineral imbalances), higher degree of vitamin degradation and higher levels of excretion into the environment.
Organic trace minerals (for example, proteinates and selenium yeast) are closer to the natural form in which animals would find trace minerals in nature; we therefore see better absorption and utilization, which means higher bioavailability and fewer dietary interactions so that organic trace minerals can typically be supplemented at lower levels.
Benefits of organic trace minerals
Advantages of organic trace minerals have been well documented and include reduced days to first service, fewer days open and increased pregnancy rates; fewer days open and fewer services; and improved ovarian activity, earlier estrus and conception, and decreased embryonic mortality.
This comes as no surprise given the impact trace mineral source can have not only on overall trace mineral status, but on gene expressions linked to reproductive performance as well, as demonstrated in a nutrigenomics study when comparing proteinated organic trace minerals to inorganic sources. In that study, researchers evaluated the effect of replacing inorganic trace minerals with organic (proteinated trace minerals and selenium yeast) on gene expression levels in replacement heifers. Results indicated that trace mineral source impacted 580 differentially expressed genes related to reproductive performance, including dendritic cell maturation, relaxin hormone signaling, Gaq signaling, function of smooth muscle tissues and thrombin signaling, all of which play essential roles in early pregnancy, indicating that organic trace mineral supplementation can potentially benefit reproductive performance, including improved regulation of the estrous cycle, shorter calving intervals and improved implantation rates.
So how do organic trace minerals affect fertility parameters in successive generations? In a recent beef study, the response of Angus and Brangus cows and their calves to either inorganic (ING) or organic (ORG) trace mineral sources was evaluated. For cows supplemented with ORG 90 days pre-calving throughout heifer developmental period (year one), heifer calves reached puberty nine days earlier and were confirmed pregnant eight days earlier than heifers from the ING-supplemented cows.
The results for year two, where cows were supplemented for the entire year and calves were thus exposed to ORG supplementation from conception throughout the heifer development period (year two), the heifers from cows supplemented with ORG reached puberty 41 days earlier and were confirmed pregnant 18 days earlier than heifers from ING-supplemented cows.
Trace mineral source and supplementation have thus had a direct effect on fertility parameters in successive generations (i.e., fetal programming effect), and year-round supplementation with a high-quality trace mineral program can have tremendous impact on both the individual animal and her female offspring’s reproductive efficiency as measured by age at puberty, age at calving and lifetime performance.
Optimizing trace mineral status and reproductive efficiency is especially important in purebred herds and operations focusing on embryos: When looking at follicular dynamics and embryo quality in beef cows, researchers have reported that supplementation with organic trace minerals results not only in increased diameter of ovulatory follicles but also leads to improved in vitro maturation and embryo cleavage. This is significant, as early embryo cleavage is a strong biological indicator of embryo potential and is often used as a measure of embryo quality.
Implications
Organic trace minerals, especially in the proteinated form, can thus potentially benefit reproductive performance, including improved regulation of the estrus cycle, shorter calving intervals and improved implantation rates, as well as reproductive efficiency in successive generations. When developing one’s own or acquiring replacement females, emphasis should thus not only be on genetics, but nutritional predisposition should also be taken into consideration. Given the potential return on investment associated with organic trace minerals in terms of health, reproductive efficiency and gains, year-round supplementation is not only an economically feasible choice but one that impacts future performance and profitability directly.
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