Supplemental Zinc Sulfate Affects Growth Performance of Finishing Heifers

Zinc is an essential mineral required for normal function of more than 300 enzymes in microorganisms, plants, and animals. Zinc-requiring enzymes participate in metabolism of nucleic acids, proteins, and carbohydrates, all of which are essential for growth of cattle. In addition, zinc is necessary for normal development and function of the immune system. The requirement for zinc in finishing cattle diets has been established at 30 ppm (NRC, Nutrient Requirements of Beef Cattle, 2000), though concentrations recommended by consulting nutritionists and feed manufacturers span a far broader range. The purpose of this study was to evaluate the effects of feeding different levels of zinc on feedlot performance and carcass traits of finishing heifers

Short-term fasts increase levels of halogenated flame retardants in tissues of a wild incubating bird

Many species are adapted for fasting during parts of their life cycle. For species undergoing extreme fasts, lipid stores are mobilized and accumulated contaminants can be released to exert toxicological effects. However, it is unknown if short-term fasting events may have a similar effect. The objective of this study was to determine if short successive fasts are related to contaminant levels in liver and plasma of birds. In ring-billed gulls (Larus delawarensis), both members of the pair alternate between incubating the nest for several hours (during which they fast) and foraging, making them a useful model for examining this question. Birds were equipped with miniature data loggers recording time and GPS position for two days to determine the proportion and duration of time birds spent in these two activities. Liver and plasma samples were collected, and halogenated flame retardants (HFRs) (PBDEs and dechlorane plus) and organochlorines (OCs) (PCBs, DDTs, and chlordane-related compounds) were determined. Most birds (79%) exhibited plasma lipid content below 1%, indicating a likely fasted state, and plasma lipid percent declined with the number of hours spent at the nest site. The more time birds spent at their nest site, the higher were their plasma and liver concentrations of HFRs. However, body condition indices were unrelated to either the amount of time birds fasted at the nest site or contaminant levels, suggesting that lipid mobilization might not have been severe enough to affect overall body condition of birds and to explain the relationship between fasting and HFR concentrations. A similar relationship between fasting and OC levels was not observed, suggesting that different factors are affecting short-term temporal variations in concentrations of these two classes of contaminants. This study demonstrates that short fasts can be related to increased internal contaminant exposure in birds and that this may be a confounding factor in research and monitoring involving tissue concentrations of HFRs in wild birds. © 2015 Elsevier Inc

Lactipro (Megasphaera elsdenii) Increases Ruminal pH and Alters Volatile Fatty Acids and Lactate During Transition to an 80% Concentrate Diet

Direct-fed microbials commonly have been used to enhance performance or to decrease shedding of foodborne pathogens in beef cattle. Megasphaera elsdenii is a recently introduced probiotic bacteria marketed under the trade name Lactipro (MS-Biotec Inc., Wamego, KS) and is a key lactate-fermenting bacterium in the rumens of cattle fed high-concentrate diets. Megasphaera elsdenii is responsible for metabolizing up to 95% lactic acid within the rumen, and thus is an important species for controlling occurrence of ruminal acidosis. The objective of this study was to evaluate changes in ruminal pH and volatile fatty acid concentration during the transition from a diet with 60% concentrate to a diet containing 80% concentrate after administering five different oral dosages of Lactipro

Dietary Chromium Propionate Combined with Yeast Minimally Affects Growth Performance and Carcass Traits of Finishing Steers

Chromium (Cr) is an essential micromineral that serves to increase absorption of glucose from blood by potentiating the action of insulin. The ability to increase glucose tolerance could lead to more efficient use of glucose and ultimately to improved growth and efficiency. In addition, Cr may be beneficial in improving the immune response of cattle that are subjected to periods of stress. Organic forms of Cr (i.e., Cr propionate) increase absorption and are more physiologically active than their inorganic counterparts. Chromium propionate is currently the only approved form of organic Cr allowed for supplementation in cattle diets in the United States. Yeast supplements, most commonly in the form of various strains of Saccharomyces cerevisiae, are commonly added to livestock diets as a means of stimulating digestion, intake, and animal performance. The purpose of this experiment was to compare feedlot performance, carcass characteristics, and plasma glucose profiles of cattle fed finishing diets with and without a combination of chromium propionate and yeast supplementation

Ruminally-Protected Lysine (SafeGain) Improves Performance of Growing Beef Cattle

Lysine frequently is cited as the first-limiting amino acid for cattle diets. Synthetic lysine, while routinely added to pig diets, is ineffective in fulfilling lysine requirements of cattle due to extensive degradation by microbes within the rumen. Lysine can be encapsulated with compounds, such as saturated fats, that minimize degradation by ruminal microbes, thereby assuring that a greater proportion of the amino acid is available for absorption post-ruminally. The purpose of this experiment was to measure the impact of SafeGain (H.J. Baker & Bro. Inc., Little Rock, AR), an encapsulated form of lysine sulfate, on rate of gain and feed efficiency in backgrounding cattle

Supplemental Zinc Oxide Does Not Interact With Zilmax in Feedlot Steers

Zilmax (Merck Animal Health; Summit, NJ) is in a class of feed additives known as beta agonists and is designed to improve production efficiency in cattle when fed 20 days prior to harvest. Zilmax works by altering deposition of body tissue to more lean muscle than fat. Zinc is an essential mineral necessary for normal growth and development of all mammals. Zinc functions largely in enzymes involved in protein synthesis and carbohydrate metabolism along with many other biological reactions. The purpose of this study was to assess changes in blood components and to evaluate the interactive effects of zinc and Zilmax supplementation on growth and carcass characteristics of finishing steers

Hops Βeta-Acid Extract Yields Feedlot Performance Similar to Rumensin

Hops (Humulus lupulus) have played an integral role in beer manufacturing and are widely known for their antimicrobial and preservative properties. α-acids of hops are extracted and utilized to enhance beer flavor, leaving residues largely composed of β-acids. Beta-acid extracts of hops are structurally similar to ionophores and may express ionophore-like traits. Ionophores, including Rumensin (Elanco Animal Health, Greenfield, IN), are used to improve feed efficiency and to decrease the incidence of digestive disturbances in feedlot cattle. A large portion of in vitro studies show benefits from feeding hops or hop acids with results similar to ionophores; however, live animal experiments are needed to confirm these observations. The objectives of this study were to assess the effects of β-acid extracts of hops on feedlot performance in cattle fed high-concentrate diets and determine a response to varied doses of β-acid extracts of hops

Antioxidant Feeding Does Not Impact Incidence or Severity of Liver Abscesses

Liver abscesses are a large source of economic loss in feedlot cattle. Not only do liver abscesses lead to a decrease in feedlot performance, but these livers are condemned in the abattoir and can also lead to a further decrease in carcass value due to trim loss. Tylosin phosphate is a metaphylactic macrolide drug that effectively decreases the occurrence of liver abscesses. The drug is approved by the Food and Drug Administration for over-the-counter use. However, in January 2017 the FDA will require a veterinary feed directive for medically important antibiotics (antibiotics that are used in human health) used in production animal feed. Macrolides are one class of antibiotic that will require a veterinary feed directive. A drug that is accompanied by a veterinary feed directive will require it to be used within the regulations that the FDA has set for the specific drug. This new directive is to encourage the animal production industry to use less medically important antibiotics. It is therefore important to look at alternatives to control liver abscesses in feedlot cattle. Various studies have shown that α-tocopherol acetate increases the humoral response and that ascorbate increases mononuclear lymphocyte counts. These antioxidants are also known to maintain the integrity and structure of ruminal papillae, thereby inhibiting pathogenic bacteria that lead to the formation of liver abscesses from gaining access to the portal blood and then eventually the liver. The objective of this study was to evaluate the impact of antioxidants on feedlot performance, carcass characteristics, and incidence and severity of liver abscesses in finishing heifers

Intermittent Feeding of Tylan Reduces Use of In-Feed Antibiotics While Still Controlling Incidence of Liver Abscesses in Finishing Steers

Liver abscesses are a cause of concern for many feedlots across the country as they lead to a decrease in feedlot performance of finishing cattle as well as a decrease in the final carcass value. Loss in carcass value is due to not only the abscessed liver being condemned, but also due to trim loss associated with the condemned liver. The macrolide drug tylosin phosphate is the drug of choice for metaphylactic treatment of liver abscesses in feedlot cattle. The Food and Drug Administration approved the drug for over-the-counter use, however, from January 2017 all medically important (used in human health) antibiotics that are to be fed in production animal diets will require a veterinary feed directive. The objective of the veterinary feed directive program is to decrease the use of medically important antibiotics in animal production. These veterinary feed directives are similar to a prescription and will encourage the use of the drug in accordance to FDA-guidelines associated with that drug. Macrolide antibiotics are considered medically important and will need a veterinary feed directive. Therefore, it is imperative to look at different methods to control liver abscesses in feedlot cattle. Various studies have noted that macrolide antibiotics (such as tylosin phosphate) are effective against pathogens for moderate to prolonged periods after initial use. The purpose of this study was to determine whether feeding tylosin phosphate periodically throughout the finishing period will have a comparable effect on decreasing liver abscesses as when we would feed tylosin phosphate continuously through the finishing period

Carryover Effects of Crude Glycerin Fed During the Growing Phase on Finishing Cattle Performance and Carcass Characteristics

Crude glycerin is a byproduct of biodiesel production, and its use as a feedstuff for cattle has expanded in the last decade due to increased availability and favorable pricing compared with other energy concentrates such as cereal grains. Incorporation of glycerin into cereal-based finishing diets, at levels up to 8%, has been shown to improve cattle performance; however, it decreases activity of cellulolytic microorganisms in the rumen, ultimately decreasing fiber digestion. Most of the studies conducted to date have evaluated glycerin in finishing diets that contain relatively small amounts of fiber, but little is known of its value as an energy source for growing cattle that typically are fed diets containing greater proportions of fiber. Moreover, possible carryover effects from feeding glycerin in the growing phase and effects on finishing performance and carcass characteristics are unknown. In this study, we wanted to evaluate glycerin as a component of diets fed throughout a 90-day backgrounding phase to determine its impact on performance and carcass characteristics of heifers during the subsequent finishing phase when they were no longer fed glycerin