by: Stephen B. Blezinger
Ph.D., PAS

Part 1

Research over recent years has shown, repeatedly, that improving the nutrition of the cow at and post conception and through the entire gestational period will improve calf survival (lower dystocia rates), growth (greater weaning weights) and health (lower rates of sickess and deathloss prior to weaning). It has also been shown to improve the quality of colostrum produced by the cow during the during the hours immediately after birth. Colostrum increases the level of antibodies the calf receives and is critical to the early immune response function and calf health. The primary exception to the overall practice of improving nutrition during pregnancy occurs during the final ~2 months of gestation when the most significant overall fetal growth occurs. Over supplementation (primarily energy) of the dam during this period can result in excessive fetal growth that has been attributed to calving difficulties and increased dystocia at delivery. So just as under nutrition during this period is detrimental to the calf, over-nutrition creates problems as well.

Fetal or developmental programming has been discussed extensively recently and it is recognized that good maternal nutrition is advised to produce a healthy vigorous calf. The producer is advised to provide proper nutrition (based on NRC guidelines) to insure body condition scores are adequate, initially, to insure timely breeding or rebreeding. Subsequently, a variety of nutritional guidelines have been outlined to insure the cow breeds properly and the resulting calf is healthy and productive. But more current data has emerged that illustrates a need for optimized or strategized nutrition for the cow during critical developmental stages. There is no time in the life of the calf where cell, tissue, organ and systemic development occurs more rapidly than during the first few weeks after conception and then through the rest of the gestational period. Given this rapid rate of development the embryo/fetus' need for proper nutrients, properly timed is critical.

In previous articles we've discussed the concept of developmental programming and have established its validity and value for the producer. It has been discussed how the various nutrients are essential for normal development and growth of the unborn calf. Further research has shown that the concept goes beyond laying the groundwork for a healthy productive calf. We know from a variety of studies that strategic maternal nutrition can also affect the calf's ability to produce a carcass to its genetic potential. Left to chance, the calf may or may not reach this potential under general management and feeding programs or even if grown and finished under exceptional programs. If the basic components are not established during the early developmental embryonic or fetal stages, maximizing the young animal's genetic potential may not be possible.

In the following article we'll take a look beyond the basics of development as affected by the cow's nutrition. We'll examine how strategic nutrition can work to optimize the establishment of muscle and adipose (fat) tissue that are essential for the production of a quality carcass and meat in the growing animal.

Why Should the Producer Bother?

In discussing these concepts many producers I've talked with have asked me this question. “Why should I concern myself with this type of thing? It's complicated and makes my head hurt!” We are living in a rapidly changing world and rapidly changing and evolving food industry. Part of these changes have created the results we've seen in the cattle markets that include:

1) Historically unprecedented cattle prices.

2) Lower cattle numbers than we have seen since the 1950's.

3) Continued demand despite high beef prices in the meat case or on the restaurant menu.

4) Continued pressure by society, media and medicine to reduce meat consumption overall

5) A growing and expanding world market with increasing buying power and a growing demand for protein.

These and numerous other circumstances are telling the cattle industry that it has to make changes in how we produce our product at the most basic level -- on the farm or ranch. We have to take a hard look at how we produce the calves we do as they are the starting point of the beef production pipeline. The “status” of these calves, as they hit the ground will influence the beef product that enters the food supply chain 18 or so months later. There is a growing need for the producer to understand how to produce a better beef supply. Much of this starts with the genetics he/she combines but is, just as importantly, significantly affected by how he manages that overall system from the point of breeding until the animal leaves his operation. This not only affects the overall product produced but the operation's bottom line. So the producer most definitely can answer the question: “why should I bother?” Because it affects your profitability!

Producing More Pounds -- Producing Better Pounds

The goal of the cattleman is to efficiently and cost effectively produce more pounds of beef per cow, per acre of per whatever base of measurement chosen to assess profitability. This discussion is designed to help the producer see that there are critical tools available to “stack the deck” in his favor.

Meat animals are raised for their skeletal muscle. The fetal stage is crucial for skeletal muscle development because there is no net increase in muscle fiber numbers after birth (Stickland, 1978; Zhu et al., 2004). Therefore, a decrease in the number of muscle fibers because of fetal programming permanently reduces muscle mass and negatively affects animal performance.

Secondly, marbling (i.e., intramuscular fat) is crucial for meat palatability, and fetal life is a major stage for generation of intramuscular adipocytes (fat cells, Tong et al., 2008), which provide the sites for intramuscular fat accumulation or marbling formation during fattening. Thus, fetal programming also affects marbling in offspring cattle.

As mentioned above, at the end of the day, the producer wants to sell more pounds of beef when the calf leaves his ownership. For the cow/calf producer that is selling calves at weaning. If the producer is retaining ownership and selling these calves out of the feedyard, the quality of this beef (carcass, marbling, etc.) is also a concern as this directly affects the value per pound of product.

So back to how the basic mechanics of embryo and fetus development works.

For the first couple of months after conception the embryo is growing rapidly and developing critical tissues, organs and systems. Nutrients needed for this process are not large in volume but specific in nature. Nutrients are also prioritized, meaning that nutrients will be used or applied first for critical, essential tissues such as heart, liver, immune system, etc.

There are two very critical events that must occur initially for subsequent development of the calf. First, the new animal's DNA (deoxyribonucleic acid, the blueprint for life) is established at the point of conception and is a combination of that DNA delivered from the sire in the sperm and from the dam in the ova. This is the true mechanics of the selections breeders make when mating specific bulls and cows. Many producers carefully consider EPD's which provide an indicator of what an animal's genetic potential is for traits like birth weight, weaning weight, milk production and so on. These EPD values have a physiological base in the genetic material that is the basis for this performance. Purebred breeders invest significant dollars in “genetics.” Thus, providing the proper nutritional and management support for the dam is critical to optimizing the expression of the genetic investment.

To review, the DNA begins its role almost immediately after conception, instructing the fertilized egg cell to begin dividing and transitioning into an embryo and then a fetus. The DNA blueprint then goes on to set the protocol for how the tissues and various physiological systems in the growing body develop. This is a key period of time. During these very early stages (only a few days after conception) the new embryo is undergoing exponential growth, some of the most rapid cellular division in its entire life. If conditions (including nutrition) are not optimal, opportunity exists for problems or errors to occur in the genetic codes or instructions. This is where a material known as RNA or Ribonucleic Acid comes into the picture. While DNA is the instruction manual that resides in the nucleus of the cells, RNA leaves the nucleus and the cells and is essentially the individual pages of the instruction manual. It provides specific instructions on how the countless actions and reactions in the cells, tissues and entire body are to occur.

This is where a significant opportunity for problems to develop. While DNA is very stable, has methods of error detection and the means to correct these errors, RNA does not have these same capabilities. Both DNA and RNA make copies of themselves. DNA copies are generally very good. With RNA this is not always the case. RNA can make flawed copies of itself and does not really have a way to repair these flaws. Additionally, RNA replicates itself about 10 times faster than DNA so appropriate nutritional building blocks must be in place constantly to support this copying process (Blezinger, 2012).

The second important step is how the embryo connects to the dam and more importantly to the dam's blood supply. This placental connection is believed to be an equally important factor in the fetal programming process as it establishes the delivery system for all nutrients and critical compounds from the cow to the developing embryo/fetus. Establishment of functional uteroplacental and fetal circulation is one of the earliest events during embryonic and placental development (Patten, 1964; Ramsey, 1982) allowing for transportation of all respiratory gases, nutrient, and waste exchanges between the maternal and fetal systems (Reynolds and Redmer, 1995; 2001). The efficiency of transport is related to the blood flow between the uterus and the placenta (Reynolds and Redmer, 1995) and although placental growth slows during the last half of gestation, blood flow to the placenta increases three to fourfold from mid to late gestation to support the exponential rate of fetal growth (Rosenfeld et al., 1974; Reynolds et al., 1986; Metcalfe et al., 1988; Ferrell, 1989).

So once the embryo is created with its developmental plan in place and the blood flow connection between the uterus (cow), placenta and the embryo has been established, transfer of necessary nutrients can begin taking place effectively.

Now that we've established the basics, in Part 2 of this series we'll go on to discuss the specific effects on the animal's performance, why this important to the producer and how we can develop a specific strategy that will help maximize the animal's performance in a very tangible manner.

Copyright 2015 – Dr. Stephen B. Blezinger. Dr. Steve Blezinger is and nutritional and management consultant with an office in Sulphur Springs Texas. He can be reached by e-mail at [email protected] For more information please visit us on Facebook at Reveille Livestock Concepts.

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