by: Stephen B. Blezinger
Most cattle producers have a nutrition program of one type or another. Some are very well structured, perhaps even having been designed working with a nutritionist. Others are less sophisticated and are the results of getting recommendations at the local feed store or coffee shop. Some are very simple and include grazing on pasture, feeding some hay in winter and throwing out some range cubes when you want to call the cows up to gather calves (this is the program I grew up with).
Every cattle operation needs a sound nutrition program if they have ANY interest in how cattle perform, how well cows breed and produce calves and how much the calves weigh at weaning particularly if that's when they are marketed.
Most producers understand things like protein, energy, minerals and vitamins. These aside from air and water, these are the foundational nutrients every animal needs. Protein (composed of amino acids) are the building blocks of bone, muscle and countless other biochemicals required for every function in the body. Energy is the fuel that drives all the reactions in the body and establishes rates of gain, milk production, mobility, etc. Minerals and vitamins work like the nuts and bolts of cellular, tissue and organ development as well as function as components or cofactors in the countless chemical and enzymatic reactions required for day-to-day metabolism and performance.
So, it's well established that all of these nutrients are needed and critical.
But consider the following – not only does the cow need these nutrients, they are required in a certain prioritized manner. In other words, while the animal needs them all, in some cases one may be required more than another.
First Limiting Nutrients
Prioritization of nutrients can mean different things. One of the first concepts to understand is that of “first limiting nutrient.” On any given day, a cow standing out in the pasture will consume a combination of most, if not all, of the various nutrients. If she is on a farm or ranch that has a particularly good, well designed nutrition program that is being effectively delivered, the likelihood is good she is meeting all of her nutrient requirements. One thing to remember, however, is that just because she is standing knee deep in lush green grass, this does not mean she is receiving everything she needs, nutritionally.
If she is on a typical farm, she may or may not be receiving all the nutrients required even though care is being taken to supplement those nutrients believed to be short. No matter the case, it is not unusual for the animal to be short in one nutrient or another.
The first limiting nutrient is the one that is in the shortest supply relative to the animal's requirements. Picture this as a barrel with the staves cut to varying lengths. The barrel will hold water up to the depth equal to the shortest stave. Now imagine that stave is a nutrient – protein, energy, fat, calcium, phosphorus, zinc, copper, vitamin A. The animal will perform up to the level of availability of that nutrient in the shortest supply. If the animal is adequate or better in all the nutrients except for, say, calcium, she will perform up to the point that her calcium demand is met by her diet. One qualifier here – for mature animals where bone development is complete, if her diet is inadequate in Ca, her body may very well mobilize or pull Ca for that stored in bones to meet this demand, particularly if her nutritional supply is beneath that needed for simple maintenance requirements. In this case, a prolonged deficiency will not only limit performance (i.e. milking ability) but may create other problems such as hypocalcemia or even bone fragility.
Limitations in availability are not quite as obvious with the “smaller” nutrients such as the minerals and vitamins when compared to protein and energy deficiencies. Inadequate supplies of these major nutrients are readily seen in reproductive performance, milking ability, calf growth, age at puberty, immune response, etc. This would lead us to believe that we need to be sure to take care of protein and energy requirements first. To a certain degree that may be true, primarily since the animal needs much larger amounts of these nutrients. However, recall that the minerals and vitamins are described as the nuts and bolts that hold things together. This is absolutely true. As noted in the example above, a dietary shortage of one of the more “minor” nutrients can and will soon lead to performance problems as well as simple metabolic or maintenance issues. At some point, sooner or later, shorting the animal of even the most minor nutrient will create a problem of some type.
So, do we truly prioritize nutrients in an order of importance to the animal and is this based on the quantity or volume needed by the animal on a day to day basis? For instance, the cow needs pounds of protein per day but only milligrams of some of the trace elements and vitamins. This becomes particularly relevant if multiple nutrient are short and there are limited resources to provide these. So if you have to choose between providing protein or copper, it is probably more important to provide for the protein needs most immediately. However, the remaining nutrients that are short should be supplied as soon as possible.
From this respect, we can summarize by saying that if the producer is required to prioritize provision of nutrients the more major nutrients should be targeted first but the remaining ones should follow as quickly as possible. Remember, for optimal animal performance, all the nutrients must be supplied to meet the animal's requirements.
Delivery is a Key
Since most cow/calf programs are based on forages (pastures and harvested/stored), providing the best forage economically feasible is another key. With proper soil fertility and correct plant variety selections, many nutrients are available to the animal for very significant periods of the production year. Perhaps even most of the year. In some cases, such as range grazing where use of improved plant varieties, moisture, fertilization, etc. are infeasible, plant nutrient availability may be somewhat limited. However, in many cases, range plants are quite nutrient dense and are mainly limited by quantity, requiring substantially more acreage to provide the same volume.
On most operations, at least some supplementation is required at certain times of the year. This is where delivery can become an issue. For labor saving purposes, free choice supplements have been popular for years. These include limiter feeds (salt or other technologies), liquid feeds, tubs and blocks and free-choice minerals. And while these products can be formulated to provide the needed nutrients at a given intake level, getting the entire cow herd to consume a particular supplement at the target intake is very challenging. Intake is affected by a variety of factors including palatability of the supplement, availability and quality of the base forage, nutrient demand by the cow, animal blood chemistry, environment, etc. This becomes even more complex and variable when multiple self-fed/free-choice supplements are used (i.e. liquid feed and free choice minerals). Since the availability of one may very well affect the consumption of the other. It is always important to coordinate the nutrient values in all forage and feed or supplement sources to optimize nutrient levels for the animal and to insure proper economics. Over or underfeeding is expensive and problematic.
Supplement feeding and feeder management is extremely important. Dropping a feeder out in the pasture and seldom checking it will result in underfeeding all the time. Make sure feeders are checked regularly (once or twice per week, preferably on the same days). With free-choice minerals, always carry bags of mineral whenever checking cows so feeders can be filled. During mild winters and periods of spring and early pasture growth feeders may need to be moved closer to water or to resting areas to encourage intake.
Understanding nutrient prioritization is important in effective nutritional management. Regular forage testing and comparison with supplements can help insure nutrients are provided in a prioritized manner and are supplied at proper levels for the animals requirements.
Copyright April 2017 – 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 phone at (903) 352-3475 or by e-mail at email@example.com. For more information please visit us on Facebook at Reveille Livestock Concepts.
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