Fetal nutrition has long-term effect

Written by Dr. Jim White on .

Evidence continues to mount that you should start managing calves before they are born. That’s a tough thing to do, you say, but if you think about it, it’s not. “Fetal programming,” or developmental programming is the idea that maternal stimulus at critical times in fetal development has long-term impacts on the offspring.

As beef producers, you are used to hearing about studies to see how nutrition impacts health and productivity of a calf. Traditionally, these studies have been post-natal, or after the calf is born. This makes a lot of sense. At that point, the animal is identified as an individual, its situation (its genetics and environment) is unique.

But how did it do up until birth? Did it get proper nutrition? Was its immune system bolstered? While maternal nutrition during pregnancy plays an essential role in proper fetal and placental development, less is known about how maternal nutrition impacts the long-term health and productivity of the offspring.

A cow in gestation is eating for two. Clearly, prenatal growth is sensitive to the direct and indirect effects of maternal diet—basically from just after conception.

In general terms, though, herd management has evolved as if undernutrition of a pregnant cow during the early stages of fetal development isn’t much to worry about. After all, what nutrient requirements could a fetus really need during the first half of gestation? At least, this was the conventional wisdom back when I was in grad school. That’s because some 75 percent of the growth for a ruminant fetus happens in the last two months of gestation. But, according to work from K.A. Vonnahme at North Dakota State University, “it is during this early phase of fetal development that maximal placental growth, differentiation and vascularization occurs, as well as fetal organogenesis.” All of these are critical for fetal development.

If that early growth is challenged, it can compromise the animal’s longterm performance. In other words, not only is neonatal health compromised, but the subsequent health may be “programmed” as offspring from undernourished dams have been shown to exhibit poor growth and productivity and also to develop significant diseases later in life.

In commercial cattle production settings, undernutrition often occurs during gestation—especially during the first two trimesters. This results from either low feed reserves or management practices that result in cows losing weight during late fall and early winter.

This theory of developmental programming has been experimentally challenged and verified using several animal models, particularly rats. Here is where it gets tricky. Variations in the duration and severity of maternal undernutrition do not always result in a reduced birth weight. Physiologic alterations such as glucose intolerance, skewed growth patterns and alterations in carcass characteristics have been reported. Thus, birth weight alone may not be the best predictor for calf survival and productivity. Research at NDSU shows that beef cows bred to the same bull and carrying female fetuses delivered calves of similar birth weight in situations when they were fed adequately and when they were underfed.

According to Vonnahme, previous studies of sheep and humans have demonstrated that an extended period of maternal underfeeding during the first half of gestation results in relatively normal birth weights. However, it leads to increases in the length and thinness of the newborn. The practical significance of fetal programming lies in the associations between reductions in maternal nutrition during early gestation and the risk of abnormalities in muscle function, mineralization of bone and organ function. Unfortunately, at present, little is known about the specific nutrient induced changes that end up causing poor development later in the animal’s life.

Research does show that feeding pregnant rats a low-protein diet results in lifelong elevations in blood pressure in the offspring. Increases in fetal blood pressure are known to result in alterations in blood flow to the lungs, and as a result, to long-term lung function.

That’s just rats, of course. But consider the fact that bovine respiratory diseases make up the majority of illness and death loss in feedlots. According to Vonnahme’s roundup of the research, historically, 15 to 45 percent of feedlot cattle have been affected with bovine respiratory disease (BRD). In fact, some 1 to 5 percent of total cattle placed on feed traditionally die of BRD. Respiratory disease alone accounts for 44 percent of deaths in beef feedlot cattle. It is possible that gestational nutrient restriction could increase susceptibility of cattle to respiratory disease during later life, especially in the feedlot.

Aside from disease, Vonnahme’s research suggests that long-term muscle development is also affected by maternal nutrition. “Growth restriction seems to be especially important when fetal muscle development is adversely affected. Skeletal muscle has a lower priority in nutrient partitioning compared to the brain and heart in response to the challenges to the fetus during development, rendering it particularly vulnerable to nutrient deficiency,” he reported. Basically, maternal growth is critical for muscle development because that’s when the number of muscle fibers is established. Muscles grow after birth, of course, but the base number of fibers is already set.

According to Vonnahme, “steers from cows which were nutritionally restricted during gestation had lower live and carcass weights compared to steers from adequately fed cows at 30 months of age.”

Vonnahme pointed out that retail yield on the carcasses, based on fatness, were greater in the steers from nutritionally restricted cows, indicating that while growth may be hindered in offspring from cows receiving low nutrition during pregnancy, ability to accumulate fat is not. The quality grade is another matter. MFA has developed a nutrigenomic technology with Ricochet that will focus on these issues. It will be available later this year.

Fiber is critical to horse nutrition

Written by Dr. Jim White on .

Grazing is a full-time job for horses. Given their preference, they would graze for 12 hours or more every day. Horses’ broad, flat teeth and sideways chewing motions make short work of the tough, stemmy grasses and weeds they favor. Given that horses ferment ingested fiber in their hind gut, they can make a living on lower quality forage than a cow can. Horses don’t need to reduce the fiber as much as cows. You can see it by comparing horse fecals to cow fecals. Horse fecals have significantly larger forage particles. The goal of the horse digestive tract is to get available, rapidly digestible nutrients from feedstuffs and move it through. They make up what the gut doesn’t use by volume of intake. Horses get a significant portion of their energy from the fermentation acids in the hind gut, but the proportion of their energy need met by these organic acids will be lower than that seen in cattle. The usual number given is that the fermentation of fiber to organic acids in the hind gut provides 30 to 70 percent of the animal’s energy.

It’s common to feed grains and fat to horses (for example, MFA Eazykeeper or Legends feed) to provide additional energy the animal may need. But, it is important to remember that fiber is an essential and important part of any equine diet— with the possible exception of very young foals. Dietary fiber provides energy horses need for everyday maintenance metabolism. Without adequate fiber, the horse’s digestive system doesn’t function properly and puts the horse at increased risk of metabolic diseases.

In terms of horse nutrition, when we discuss fiber, we are talking about the cell walls of plants. Plants have a rather substantial cell wall and it will be variable in digestibility. The material on the inside of the cell tends to be very digestible. The way to determine the amount of fiber (cell wall) is to sample the forage and process it in a small machine that is sort of like a washing machine. We use detergent to break up the cells and put starch/protein into solution. It is then spun down. What’s left is the fiber-cell walls. Feed labs will call this neutral detergent fiber (NDF). This is principally cellulose, hemicellulose and lignin. If acid is added to the washing\ machine, it chews through some of the fiber, principally the hemicellulose, to give us the acid detergent fiber (ADF). The lignin is not digestible, the cellulose and the hemicellulose will vary in digestibility. In legumes, about 75 percent of the NDF is ADF. In grasses, the ADF is about 66 percent. Grasses will tend to have more fiber than legumes, and the lignin in grasses tends to do a better job of protecting fiber from fermentation.

When a forage sample is sent off to the lab, the energy values that are determined are calculations from the ADF number. Forages with lower ADF numbers give higher energy values. Young forages have higher values than more mature forages. Legumes have higher energy values than grasses at the same stage of maturity. Cool-season grasses have higher energy values than warm-season grasses at the same maturity.

The rule of thumb is that fiber should be, at the least, half of a horse’s daily diet. Plenty of horses survive on more of a 100-percent-fiber diet. But that kind of feeding is giving the animals too much forage as a percent of the diet. While a forage base may very well meet the animal’s energy and protein needs, it will not meet the animal’s mineral needs. It will certainly be short of sodium, and in much of the Midwest, it will lack iodine, selenium, zinc and vitamin E. Given those caveats, an easy keeper will often make a living on principally a forage diet. To get what’s missing from the forage diet, a complete horse feed is an option. Some horses might require a concentrate to maintain animal performance. Either way, while the feed fraction of the diet may be optional, the forage component is not.

Remember, too, that not all fiber is created equally. Depending on where it came from and how old the plants were, forage-based fiber widely varies in quality, digestibility and palatability.

Don’t let your herd’s health fly away

Written by Dr. Jim White on .

Use more than one approach for fly control. 

Flies cause substantial economical losses to cattle producers. For example, biting flies carry diseases such as anaplasmosis and bovine leukosis virus, while face flies can spread pink-eye from animal to animal. Unfortunately, you will never completely eliminate fly problems in your herd. Flies are well-adapted to the environment; they have been around for thousands of years and are doing very well for themselves.

The adaptability of flies means that it is going to be impossible to completely remove them from your operation. However, there are ways to control flies and to lessen their negative impact. These practices each have their benefits and drawbacks. Using a combination of these practices can improve control.

You should evaluate your herd, your environment and your fly pressure to choose which is best for your livestock.

Feed an insect growth regulator or a larvicide

There are a variety of these products available, depending on your needs. They include Altosid for horn flies, or Rabon for horn, face, house and stable flies. ClariFly is product used mainly with confinement cattle. The larvicide or insect growth regulator should be fed starting 30 days before flies typically appear, and should be continued for 30 days after a killing frost. This means feeding the product from about mid-March to mid November. While horn flies don’t travel far, face flies will travel a mile or two. This means that if your neighbors have cattle, you may inherit some of their flies—unless they have joined the fray and are aggressive about knocking down fly populations.

Use fly tags

Newer-generation fly tags are useful in controlling fly populations. To reduce pyrethroid resistance, after using pyrethroid tags for two consecutive years, switch to an organophosphate tag for one year. For optimal fly control, many products require two tags for an adult animal and one tag for a calf. As always, whenever you are using a pesticide, read and follow  label directions. The rules governing pesticide and insecticide are federal rules. You really don’t want to run afoul of them.

Applying the tags too early will result in less effective fly control. The ideal time to apply tags is when there are about 200 horn flies per cow. The best time to check this is in the early morning hours. Mornings are cooler, and the wind tends to be calm. Observe livestock while the animals are up and grazing. It is relatively easy to see the flies on their sides.

Use pour-ons

Pour-ons require labor, but are effective fly deterrents. You can apply a pour-on at the same time you fly-tag your cattle. If you do this during spring turnout, you can use a product that kills internal parasites, as these products are also effective against flies. If you apply a pour-on later in the year, use products that are just labeled for flies and/or lice.

Provide dust bags/cattle rubs

If you place a dust bag or rub at a site where all cattle use it, keep it charged with insecticide. Rubs are an economical means of controlling face and horn flies.

Spray cattle

If you use a spray product on your cattle at timely intervals, it can be very effective at reducing the fly population. Though useful, it is time consuming, and control can be sporadic.

When working on controlling flies and lessening their damage to your cattle, it is unlikely that one strategy alone will be sufficient. When you use several methods in conjunction, you are better able to lessen the negative impact of flies.

Parasites eat your profits

Written by Dr. Jim White on .

Control lice in the winter and horn flies in the summer.

Lice puncture the skin of host animals to take their meals. Biting lice scrape and irritate the animal’s skin. Parasites cost you money. Drivers of economic loss associated with them include reduced average daily gain and weaning weights, decreased feed efficiency and increased susceptibility to disease.

Infestations of biting and sucking lice have been associated with reduced weight gains and general unthriftiness of cattle. The economic impact of these small insects has been very difficult to assess. However, it appears that an average of 10 insects or more per square inch will have a significant effect.

Moderate-to-heavy infestations add to the impact of cold weather, shipping stress, inadequate nutrition, harm from internal parasites or disease. The interaction between low levels of both lice and intestinal nematodes can reduce weight gains by more than 8 percent. The energy that lice steal, coupled with other factors, can have a severe impact on animal health. This impact shows itself in various ways. It can be anemia, slow recovery from diseases, poor gains or general unthriftiness.

Lice are primarily spread from animal to animal. Lice can arrive on new cattle. Any time you bring in new cattle, you need to be persistent about treating them.

It is best to assume that all purchased animals are infested. They should be isolated from the existing animals until their full course of treatment is completed. Cross-fence contact can be enough for spread of these insects, especially during the winter when louse burdens are greatest.

Lice spend their lives on the host animal. Sucking lice typically die within a few hours of being removed from the host. Biting lice, can live up to a few days off the host—under ideal conditions.

A high-energy diet seems to reduce the effects of cattle lice on weight gains, perhaps because lice populations decline on better-fed cattle, a sound feeding program and high energy ration serves as the foundation of a louse control program.

Lice interventions include insecticide sprays, pour-ons and dust. As soon as summer comes, the lice begin to disappear and horn flies roll in.

A few horn flies can reduce performance substantially; these blood feeders can take 20 to 30 meals per day. An individual horn fly only consumes 1.5 mg of blood per meal. However, when there are a large number of flies, the blood loss can be substantial. While it is not feasible to eliminate horn flies, it is well worth it to reduce horn fly pressure. Controlling horn flies on calves will likely result in calves that are 25 to 50 pounds heavier at weaning. Controlling horn flies on cows will likely result in calves being 10 to 15 pounds heavier at weaning.

The economic threshold of horn flies is about 200 per animal. This is best evaluated early in the morning, with still air. The method used for estimates is to count the number of flies on an animal’s side. If there are more than 100 flies, there will be a positive response to controlling horn flies.

Horn flies are relatively weak fliers. They spend most of their time on the animals. Females will leave hosts only to deposit eggs in fresh manure or to seek other hosts. Because horn files must lay their eggs in manure, they are susceptible to feed-through pesticides that have activity in the manure. For pasture cattle, the product of choice is Altosid. Altosid is standard in MFA mineral in a wide range of MFA mineral products. Visit with your local MFA feed representative to find one that fits your needs.

Horn flies reduce animal performance because cattle predated by horn flies will have disrupted and decreased grazing. The cattle will spend more energy on moving, rubbing, tail switching or other activities to reduce fly irritation. The skin irritation from numerous bites may result in open wounds, which can increase the risk of secondary infections. Infected lesions may result in reduced hide value. Additionally, horn flies are suspected of transmission of anaplasmosis, anthrax and other diseases.

The best fly is one that never gets to your herd. Prevention pays.

Feeding cows on a different calendar

Written by Dr. Jim White on .

Think of a cow’s nutritional needs according to her place in the cycle.

Feed is both a principal cost and a principal factor in reproductive performance. This relationship dictates the fundamental goal of cowherd nutrition programs—achieving an optimal reproductive rate for cows.

A challenge of feeding beef cows is that their nutritional requirements change dramatically during the year based on their BCS, size, pregnancy, lactation status and environmental conditions. Because of these stages, it is common to divide the cow year into four periods.

Period 1, nursing cow. She needs to get bred; her nutrient requirements will be the greatest in this period.

Period 2, cow bred and lactating. At this point, pregnancy demands are small, and peak milk is past.

Period 3, mid-gestation. At this point, the calf is weaned; this is usually the period with the lowest nutrient requirements and a prime opportunity to increase cow BCS.

Period 4, 2 to 3 months prior to calving; during this time fetal growth rate is at its highest and the cow should be in adequate flesh. Having cows underfed in period 4 can result in lighter calf birth weights, lower calf survival, lower milk production, lower calf growth and delayed estrus—which translates to later calving next year and lower weaning weights.

As cow weight increases, the nutritional requirement for energy and protein increases. BCS has gained considerable favor because it has been demonstrated that reproduction in beef cows is greatly influenced by body fatness. The goal should be to have cows calve in good body condition and avoid significant loss in condition between calving and the start of the breeding season.

Milk production places tremendous demands on cows. Peak milk usually occurs by 60 to 80 days after calving which is right before the breeding season. The nutrients spent on milk production means high-producing cows tend to get pulled down physically, which will make it more likely that she will breed later in the season. Feeding thin, high-producing cows more feed prior to reaching peak milk tends to cause them to milk more rather than to gain weight.

The age of the animal influences nutritional requirements: a young cow is still growing. Most cows found open are 2- and 3-year-olds. Young cows should be gaining about half a pound per day. If these young cows fail to rebreed, it is an indication that feeding was inadequate to the animal’s maintenance, growth and milk production nutrient requirements. If possible, young cows along with old or thin cows, should be separated and fed a more dense diet than mature cows.

Winter feeding guidelines
Quality and quantity of forage available are the major factors influencing intake. Intake is probably most influenced by the quality of forage with intake decreasing dramatically as quality decreases. When forage quality is low or average, forage intake is increased with protein supplementation but not with energy supplementation. This increase in intake caused by adequate protein supplementation, coupled with maintenance of forage digestibility, means that the total daily energy status of the cow is increased. This is a win-win situation. If protein is adequate, cows will consume about 1.8 percent of their bodyweight as forage dry matter (less if they are fat, more if they are thin). Usually energy is the most commonly deficient nutrient in beef cow diets, but protein often represents the largest out-ofpocket expense. Proper protein supplementation of poor quality forages will increase forage intake. Increased forage intake meets the cow additional energy intake. Thus, to maximize profitability, it is essential to optimize protein supplementation. Inadequate dietary protein results in low forage intake and digestibility, resulting in much poorer performance. If you are feeding hay, budget at least 2 percent of body weight as hay DM per head per day.

Mineral supplementation calcium, phosphorus, magnesium and salt are often fed as the macro minerals. Cattle on a plant-based diet will always be sodium short, and they are likely to be calcium short unless there are legumes in the forage. Phosphorous will be short in dormant-mature forages, but may be adequate in young forage. You should supplement with magnesium in the early spring to prevent grass tetany, especially on cool-season forages such as fescue and wheat pasture. Supplementation should be started about three weeks prior to initiation of grazing. The recommended intake of magnesium can be achieved by feeding Ricochet mineral all the time or Hi-Mag or Mag-ADE meal. Ca, P, Mg, and salt are required at significant amounts and are major considerations in diet formulation.

When evaluating cow herd feeding programs, bear in mind that a high percentage of problems with poor reproduction and low weaning weights can be directly attributed to inadequate energy, protein feeding or both. This is much more common and likely than vitamin or mineral deficiencies. First verify energy and protein feeding, then evaluate vitamins and minerals.


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