By Lautaro Rostoll, Ignacio Ipharraguerre, and Nicolas DiLorenzo, University of Florida NFREC
Fig. 1. Heifers fed olive oil bioactive extracts (OBE) at the NFREC Feed Efficiency Facility. Feed intake was measured daily using the GrowSafe feed intake monitoring system. Photo credit: Lautaro Rostoll.
The fact that stress is detrimental to animal performance is a well-known concept in beef cattle production. The impact of stress on cattle is observed at various levels, and it can have multiple consequences, all of them ultimately affecting growth and performance. Stress is a very complex process to define and can take place in many different forms. During a stress event, the animals may experience an inflammatory process that ultimately leads to the overproduction of certain types of proteins called pro-inflammatory acute phase proteins. These proteins have a very important role in mounting the immune response needed to fight the stressor. Some are directly involved in recruiting immune cells to the inflammation site, others inhibit microbial growth, and all of them ultimately help in decreasing the negative impact on performance. However, the production of these proteins has a cost in terms of nutrient use efficiency, and these nutrients are diverted away from productive processes into fighting an inflammatory process.
Cattle may experience stress due to excess heat, digestive upsets such as bloat and acidosis, transport, weaning, castration, and many other processes. Often, many of those processes occur almost concurrently in our typical beef production systems, creating an additional challenge that can lead to increased morbidity and decreased animal performance. The majority of the 800,000 beef calves that are born annually in Florida leave the state in a truck heading to a backgrounding, stocker, or feedlot facility, and in many cases the calves are weaned and trucked in the same day. For this reason, any opportunities to mitigate weaning and transport stress could have an impact on the post-weaning performance of Florida calves, potentially enhancing their economic value.
Olive Oil Bio-extracts
In 2017, the University of Florida, North Florida Research and Education Center (NFREC) began a series of research projects aimed at investigating the potential of olive oil bioactive extracts as a potential feed additive to mitigate stress in cattle. The idea stems from a series of studies conducted in pigs and in rodents, in which certain compounds purified from the olive trees, including fruits, leaves and stems have shown anti-inflammatory and antioxidant properties. These compounds are part of one of the largest classes of plant natural products, known as pentacyclic triterpenes and they are isolated from pomace oil, which is the residue left after olive oil extrusion. In order to test the potential of these compounds as a novel feed additive for newly weaned beef calves, at NFREC we conducted a series of in vitro (in the laboratory) an in vivo (in the animal) studies. In this edition of the Panhandle Ag e-newsletter, we will share the results of the in vivo trials.
The NFREC study
A group of 36 newly weaned Angus crossbred heifers (463 lb of BW) from the NFREC herd were assigned to the study. The heifers were housed at the NFREC Feed Efficiency Facility and were fed a common backgrounding diet comprised of corn gluten feed (61%), cottonseed hulls (32%), molasses (4%) and a mineral premix (3%) containing, or not, the olive oil bioactive extracts (OBE) tested at either 0.04 or 0.16% of the diet DM (Figure 1). After 21 days receiving their respective dietary treatments, the heifers began a period of 12 days during which they were challenged every other day with an intravenous dose of a lipopolysaccharide (LPS), which is a common endotoxin produced in the rumen. When the LPS in the rumen translocate to the blood, it causes an inflammatory response that is characterized by a decreased feed intake and increase body temperature, among other responses. This model was used to simulate a subacute chronic inflammatory process, and then be able to test the potential of OBE in mitigating that inflammatory stress.
To make sure that the model was successful in creating the inflammatory process, a group of heifers received the control diet and was not challenged with the LPS, receiving only a saline solution injection. Thus, the four treatments tested (9 heifers per treatment) were: 1) a negative control group not fed OBE and not challenged with LPS (CTLNve); 2) a positive control group, not fed OBE and challenged with LPS (CTLPve); 3) heifers fed OBE at 0.04% of the diet DM (OBE1); and 4) heifers fed OBE at 0.16% of the diet DM (OBE4). Heifers were bled every other day during the challenge to measure blood parameters indicative of an inflammatory process, and an intravaginal device was inserted to measure temperature continuously every 5 min for the 12 days of the LPS challenge.
Results from the study show that feeding OBE, particularly at the greater inclusion level, had positive effects on vaginal temperature after the endotoxin challenge (Figure 2). Additionally, the increase in the concentration of the acute phase protein haptoglobin in plasma following the endotoxin challenge was moderated in heifers fed OBE, showing a positive effect on decreasing the acute phase response (Figure 3). This was also evidenced by an increase in dry matter intake in heifers fed OBE when compared to control. Several other measurements such as liver biopsies, and many other blood parameters were conducted in this experiment to fully understand the mode of action of these bioactive extracts and are currently being analyzed. These preliminary results are very promising and are consistent with the findings in mice and pig models receiving these types of novel feed additives.
Figure 2. Effect of feeding olive oil bioactive extracts (OBE) on vaginal temperature in heifers challenged intravenously with LPS (endotoxin).
Figure 3. Effect of olive oil bioactive extracts (OBE) feeding on blood concentrations of the acute phase protein haptoglobin. A decrease in the concentration of this protein shows a positive effect of the supplement on moderating the acute phase response.
Take home message
This first study shows promising results in terms of the potential of olive oil bioactive extracts as a potential novel feed additive to enhance productivity in newly weaned cattle. A reduction in the acute phase response was observed in heifers fed OBE for 21 days prior to an endotoxin challenge. This was consistent with an increase in dry matter intake and with improvements in several blood parameters indicative of a potentially enhanced immune status. Feeding olive oil bioactive extracts may provide an opportunity to enhance the value of Florida calves, by including them in a preconditioning program post-weaning, or prior to shipping to improve subsequent animal performance.
Nicolas DiLorenzo, UF/IFAS State Beef Specialist
Nicolas DiLorenzo, UF/IFAS Beef Specialist, introduced the UF Hay Balancer decision-aid at the 2018 Northwest Florida Beef Conference in Marianna.
At the recent Northwest Beef Conference conducted in Marianna, Dr. Nicolas DiLorenzo, UF/IFAS State Beef Specialist, introduced the UF Hay Balancer, a spreadsheet that can be used to calculate the most cost effective way to supplement cattle through the winter. The UF Hay Balancer is a decision-aid tool created by the University of Florida, Panhandle Ag Extension Team with the objective of developing cost effective winter feeding programs. Winter feeding strategies for beef cattle in the Southeastern U.S. almost always include the use of hay as the base feed. However, the majority of the forage species used to produce hay in this region are warm season perennials, which can be quite limiting in terms of nutritive value. Typically, when you compare the nutrient requirements of beef cows to those provided by the hay, there is a need for additional supplementation of energy (TDN), protein, or both. The Panhandle Ag Extension Team recognized the need for a decision-aid tool to assist producers, researchers and county agents, with ration balancing using the results from a hay test. Once you have determined the quality of your base hay, the UF Hay Balancer allows you to compare a variety of by-product feeds to determine the most cost effective blend to feed your herd each day. Not only does this help you figure out what to feed, but also how much total hay and supplement will be required for the described feeding period.
It is somewhat challenging to completely describe in an article how this tool works, so just follow the basic instructions below and give it a try. There is no charge to download this helpful new tool.
Basic steps to use the UF Hay Balancer:
Download the “UF Hay Balancer” file. This is a Microsoft Excel file you can save on your computer and customize it to fit your operation:
Enable the use of macros clicking on the “Enable Content” button in the yellow ribbon on top of the file (see image below).
Instruction for use are quite simple: you can only change the information in the orange cells. Nothing else, other than orange cells, or the drop-down menus can be modified in this file.
At the “Home screen” tab, enter all your inputs. For example: average cow weight, whether she is lactating or not, type of hay to use, and more importantly, a current hay analysis. See image below for information on where to enter that information.
Select the estimated hay-feeding waste from the drop-down menu. You have the option of selecting: None (0%) for a situation without any waste, low (10%) – such as a hay trailer or sheeted bottom hay ring, moderate 30% open bottom hay ring, or high (50%), if hay is fed on the ground without a hay feeder.
Click the green button to go to the feeds library to check for accuracy on feedstuff information such as prices or nutrient composition. Alternatively, the user can click the blue button to go directly to the Balancing and Summary page.
At the Feeds Library tab, new feeds can be added or modified, changing price and nutrient composition to fit the most current analysis or price quote. Up to 200 feeds can be added to the library. Any orange cells can be modified. Clicking any of the buttons on the top, the user can go back to the Home page to change hay analysis or cow requirements, or go directly to the Summary page.
To perform the final balancing of nutrients (if needed), the user can go the Summary and Balancing page (image below). In this final page, the user can enter the amounts of feed to supplement and the program automatically calculates nutrient shortage or surplus. When either TDN or CP are needed in order to meet the cow’s requirements, a red sign will display indicating “Need more TDN” or “Need more CP”. If the requirements of either nutrient are met, a green check-mark will be displayed next to the corresponding nutrient. Note that feeds can be selected by entering the Feed number in the corresponding box. The user can find the feed numbers either on the feed library tab, or by using the “Feed # lookup” feature on the top corner of the screen. Add the desired amounts of each feed to supplement and watch the nutrient balance change in the bottom of the screen, as well as the daily cost of supplementation.
To print the final balanced diet, click the “Print this page” button. A separate window will open allowing to save the calculations as a pdf file or to print. Note that this final “Summary page” contains all the necessary information in terms of supplementation costs, cow average weight, hay analysis, and total feed needs to purchase for the entire feeding season. To modify the inputs, the orange button (go to Home Screen) will take the user to the initial screen.
On behalf of the Panhandle Ag Extension Team, we hope cattle ranchers will find this new interactive tool useful. This is by no means a complete ration balancing program, but it is a very helpful tool to identify by-product feeds that can supplement the missing energy or protein in the hay you feed to your herd. If you are not familiar with using Excel Spreadsheets and need assistance, contact your local County Agent so they can help you work through the instructions above. If you have feedback or suggestions, for improving the “UF Hay Balancer” please email Dr. Nicolas DiLorenzo.
Figure 1. Feedlot steer experiencing heat stress. (Photo by Carl Dahlen, NDSU).
Lautaro Rostoll, Jose Dubeux, and Nicolas DiLorenzo, University of Florida NFREC
Cattle producers in the Southeast have often asked questions about the need for shade, and its impact on performance. While plenty of information is available on heat stress on cattle fed finishing diets in the Midwest, surprisingly not as much information is available on heat stress by cattle grazing in the Southeastern U.S. It is for this reason that researchers at the North Florida Research and Education Center (NFREC) Beef Research Unit decided to conduct a study to evaluate the effect of providing artificial shade for replacement heifers grazing bahiagrass pastures through the summer.
You may be wondering why we are discussing shade in a December? There are two reasons for that: 1) this study has just been completed, so this is new information and 2) this may be a good time of the year to start thinking about the improvements needed before the summer heat arrives, so you are ready to take full advantage of summer forage growth. In a sense, just as it is recommended to start planning a winter feeding strategy in the summer, when commodity prices are low, now is the time to think about improvements to your summer pastures such as fences, water troughs, shade, and maintenance while it is cool enough to work without getting heat stressed yourself.
The artificial shade study
A total of 60 black-hided bred replacement heifers, that averaged 920 lbs. of body weight from the NFREC herd were enrolled in the study, which consisted of two treatments: artificial shade versus no shade while heifers were grazing bahiagrass pastures from July 17 to September 2, 2017. Heifers were allocated to each treatment balanced by breed, so that the same amount of Angus and Brangus heifers were in each treatment. Put-and-take heifers were used to maintain the same herbage allowance, thus minimizing any effect of forage availability on average daily gain (ADG). At the beginning and at the end of the study, heifers were weighed on two consecutive days to reduce the effect of gut fill on ADG. A total of 12 pens were used in the study: 6 containing shade and 6 without. Heifers in the shade treatment had one structure per pen with a shade cloth of 36 x 24 feet (Fig. 2).
Figure 2. Shade study conducted at NFREC this past summer (Photo by Lautaro Rostoll).
Figure 3 below shows the effect of shade on the average daily gain (ADG) of heifers. During the 47 days of the study, a difference of 0.47 lbs/day in weight gain was observed in the heifers that had shade in their pens, versus heifers in pens without shade.
Fig. 3. Effect of shade on ADG in black-hided replacement heifers grazing bahiagrass during the summer.
Compared with other species, cattle cannot dissipate their heat load very efficiently. Cattle do not sweat effectively and the main cooling mechanism to dissipate heat is respiration. Heat stress can cause several problems in cattle, including reduced breeding efficiency, milk production, feed intake, weight gains and even death. At temperatures above 80°F, cattle will activate physiologic mechanisms to try to cope with heat stress, and that will ultimately increase the maintenance requirements of the animal, leading to a decrease in performance. Environmental conditions contributing to heat stress include minimal cloud cover, little or no air movement, high relative humidity, and overnight low temperatures above 70°F.
Take home message
This study, although very preliminary, is one of the first of its kind conducted in the Florida Panhandle. The results show a very marked effect on animal performance when cattle are provided with some basic heat mitigation options, such as artificial shade. While the results are perhaps not that surprising, the magnitude of the drop in ADG was: 0.47 lb/day in a study with only a six week six duration. Other data collected in this study will compare the amount of time spent in the shade vs. gazing, and the effects on animal temperature by means of various devices placed on the heifers during the study. Stay tuned for more information on this in the future.
Fig. 1. Heifer development at the NFREC Feed Efficiency Facility Credit: Nicolas DiLorenzo
Nicolas DiLorenzo, State Beef Specialist, University of Florida NFREC
Even in this current, somewhat depressed, cattle market, replacement females for the Florida commercial cow herd are an annual expense of approximately $400 million. Development and selection of the best females to join a productive herd is one of the most challenging aspects of a beef operation, and two of the keys for success, not surprisingly, are: 1) start early and 2) have a plan. Weaning time is not far off.
In order to achieve the target body weight for a cycling heifer at breeding, some hurdles need to be cleared. The first challenge is to achieve an ideal average daily weight gain (ADG) to avoid over-conditioning and fat deposition, while still gaining weight at a rate that would ensure achieving the target weight in a timely manner. The main reason why this can be so difficult, is because when doing calculations about typical weaning weights and dates, and desired weight at the beginning of the breeding season, this yields a very narrow target ADG in the range of 1.5 to 2.25 lbs/d. This is often referred to as the ideal rate of gain for heifers to avoid over or under conditioning.
To complicate things even further, these newly weaned heifers will need to have a high enough protein concentration in their diet to support muscle growth, which is critical in a growing animal. When all things are considered, the ideal heifer development diet should have approximately 13-14% crude protein, and an energy content that allows the target ADG already discussed. Thus, when considering the byproducts and commodities available in this area, there is not a single one that would be able to meet some of those nutritional requirements by itself without running into metabolic problems. Another challenge then, is to have access to a mixer wagon and feed storage space in order to blend an ideal diet.
Assuming that the mixer and commodity storage are not an issue, the next problem typically is time and labor to limit feed the heifers to avoid excessive weight gains. It is possible to provide free choice feeds to target the optimal gains, but this needs to be done carefully so that nutrients are well balanced in the total mixed ration (TMR). At the University of Florida-NFREC, heifers have been developed over the last 5 years feeding a free choice diet comprised of 51% fiber pellets (AFG Feed, LLC), 22% soyhull pellets, 22% corn gluten feed pellets, and 5% of a supplement to balance minerals and provide the ionophore monensin. With this diet (13% CP, 55% TDN), heifers have ranged from 2 to 2.45 lb/d in the last few years. While these rates of gain are on the higher end of the ideal, they provide a great opportunity for the use of byproducts. There is also an option to add more fibrous ingredients (ground hay, cottonseed hulls, etc.) to decrease the rate of gain and reduce the cost of the diet.
Another approach that has been successful for many years is the use of winter annuals such as oats, triticale, rye or combinations of those. The rates of gain on a typical year (not the case of the last spring) for cattle on winter annuals are usually in the correct range (1.7-2.2 lb/d), and protein usually is not limiting. The use of winter annuals for heifer development provides a great opportunity for producers in the Panhandle, however given the variability in weather from year to year, and assuming irrigation is not an option, it may be important to have a backup plan to avoid arriving at the beginning of the breeding season with heifers in sub-optimal condition.
Take Home Message
Developing heifers with the use of byproduct feeds and commodities is an attractive option in the Panhandle of Florida. The rate of weight gain for developing heifers needs to be considered carefully, so it is imperative to plan ahead to have the feed resources available to achieve 1.5 to 2.25 lbs/hd/d. The use of winter annuals also provides an opportunity for heifer development in North Florida, considering the nutritive profile of most of those forages. However due to the reliance on adequate rainfall, it is a good idea to have a back up plan, if the forage production is not optimal.
More information on heifer development considerations can be found in the following publication:
Supplementing replacement heifers utilizing a high-fiber diet with a bulk feeder at the North Florida Research and Education Center’s beef Unit. Photo Nicolas DiLorenzo
Nicolas DiLorenzo, State Beef Specialist, University of Florida NFREC
What can you feed in bulk to cattle free-choice?
One of the most common questions that county agents and state specialists receive this time of the year is: what commodity feed can I use to supplement cattle free-choice? (provided in bulk feeders to cattle as often as they want to eat) Often this question is followed by some explanation about how inconvenient it is to “bucket feed” every day, or how expensive it is to plant winter annuals. The question is quite valid, and the reasons for free-choice feeding are also very sound: to provide decent weight gains during the winter, while minimizing the inputs, mainly in terms of the time and labor required for daily feeding.
Beef cattle producers in the Panhandle have a competitive advantage over their Central and South Florida counterparts. The existence of a very strong cotton and peanut industry in Northwest Florida, provides large amounts of high-fiber byproducts that can be utilized for cost-effective supplemental feeding strategies for beef cattle. With an annual production of 380 million lbs of peanuts (100,500 acres planted) and 191,200 bales of cotton (102,000 acres planted), the Florida Panhandle region has a steady supply of fibrous byproducts that need to find a use or be disposed of. Fortunately for many agricultural industries such as bioethanol, sugarcane, corn, soybeans, canola, cotton, peanuts and many more, cattle are great recyclers. The ability of the rumen microbes (bugs) to digest a great majority of biological compounds, but in particular fiber, makes cattle unique in terms of the flexibility for use of byproducts as feeds.
High-Fiber Cotton and Peanut Byproducts
Cattle producers have taken advantage of byproducts such as gin trash, cottonseed hulls, or peanut hulls for many years in this region. While these products are generally low in energy or protein, they can be of great help as a “filler” or “carrier” to dilute commodities with more concentrated nutrients. There has been a recent influx of agro-industries that capitalized on the abundance of some of these byproducts to create very cost effective cattle feeding options, often in the form of pelleted commodity feeds in the tri-state region. These high-fiber byproducts can facilitate the feeding of much higher quality commodities, such as corn gluten feed, distillers grain, or soybean hulls, in free-choice bulk feeders, reducing the risks from overconsumption.
Why do feeds such as corn gluten feed or soybean hulls need to be “diluted” or mixed with these high fiber byproducts? There are a few reasons. The first one is to avoid certain metabolic disorders that are common when feeding certain commodities. For example, the high sulfur content of corn gluten feed or distillers grains may lead to sulfur toxicity in cattle, a condition known as polioencephalomalacia, or simply “polio” or “blind staggers.” Similarly, over-consumption of soybean hulls by cattle can lead to the development of bloat, because of the inability of cattle to rapidly eructate (belch) the gases produced by the rapid fermentation of this soybean byproduct. Even if hay is available free-choice, cattle will overconsume nutrient-dense commodity feeds if they are available without limit. The chart below (source UGA – Considerations for Using By-Product Feeds) provides some guidelines for limits on some common byproduct feeds. Mixing high-fiber byproduct feeds with nutrient-dense commodities will allow producers to feed the mix free-choice and greatly reducing the risk of developing any metabolic disorders.
How much high-fiber byproduct should be fed?
As a general rule, byproducts such as peanut hulls or cottonseed hulls, do not need to be included at more than 20% of the diet to prevent metabolic diseases. In fact, most high-concentrate diets only require 10% of a long fiber source to maintain rumen health. In some cases high-fiber byproducts are used in greater proportions in order to “hold back” weight gains, as would be the case with developing heifers. The following chart shows a summary of several research studies conducted at the University of Florida-NFREC, where diets with varying inclusions of fibrous byproducts were feed free-choice to growing beef cattle. These can be used as a guide of how much to expect in terms of weight gain as well as feed intake.
Take home message
Back to the main question – Can I feed commodities free choice to cattle? You certainly can, if you take advantage of the fibrous byproducts from the cotton and peanut industries. When pushing cattle to gains above 3 lbs/day, the inclusion of 10 to 12% dry matter of either ground hay, peanut hulls, or cottonseed hulls in the diet dry matter may be sufficient to maintain rumen health without sacrificing daily weight gain. When backgrounding cattle, as much as 50% of the dry matter diet can be fibrous byproducts and still allow very good (perhaps even excessive) daily gains, but at a very competitive cost per pound of gain.
50% Peanut Hull diet used in an NFREC Heifer Development trial. Photo – Nicolas DiLorenzo
For more information on this topic, use the following publication links: