Trace Mineral Supplementation for Beef Cows: Dry Range Environment.

Range mineral supplementation is based on providing trace minerals not adequately provided from grazed forage in meeting beef cattle needs throughout life cycle stages. Supplementation programs should be developed with consideration of ranch production goals, economics, and practicality for implementation. Factors such as season of grazing, forage analysis, water analysis including antagonistic elements, and measured animal responses are used in mineral supplement formulation for range cattle. Mineral intake is a critical factor to a supplement program's success. Salt-based mineral products are most used under range conditions, yet there is much individual intake variation.

Trace Mineral Nutrition of Sheep.

Trace mineral nutrition of sheep often focuses on their greater susceptibility to copper toxicosis due to a lesser biliary excretion ability compared with other ruminants. Our understanding of sheep trace mineral requirements has improved for most elements allowing for a factorial approach to determining daily requirement instead of a dietary concentration. Forage trace mineral content is influenced by many factors making issues of trace mineral supplementation geographic-dependent. Oral delivery of trace elements is a preferred supplementation method, and this can be achieved through free choice trace mineralized salt or direct dietary incorporation.

Trace Mineral Metabolism: The Maternal-Fetal Bond.

Trace minerals are essential nutrients that have many biologic functions, many of which are related to metabolic activities, immune function, and antioxidant capacity. The pregnant dam provides essential nutrients to support fetal development, including trace minerals. Milk is known to be an insufficient source of many trace minerals during the early nursing neonatal period. The fetal liver is capable of concentrating minerals to generate a reserve for use during postnatal life; however, the sufficiency of this reserve is dependent upon maternal mineral status. Appropriate mineral supplementation in the gestational diet is critical to supporting fetal development, maintaining adequate antioxidant capacity to survive the birthing process, and sustain immune function and growth of the newborn animal.

Ruminant Metabolic Diseases: Perturbed Homeorhesis.

The 6-week period encompassing parturition, termed the transition period, is recognized as the most fragile period in the life cycle of the ruminant animal. The period accounts for the greatest risk of health events that can adversely affect animal health, lactational performance, and future reproductive success. Critical endocrine and metabolic adaptations take place in allowing the animal to change nutrient priorities from supporting pregnancy to sustaining lactation. A reductionist perspective of underlying pathogenesis provided minimal metabolic disease prevalence improvement. Recent research has recognized metabolic regulatory complexity and role for activated inflammatory response underpinning dysregulation of homeorhesis during transition.

Pregnancy Toxemia in Sheep and Goats.

Pregnancy toxemia is a common metabolic disease of late pregnant ewes and does, which potentially has devastating impacts on health and performance. This metabolic syndrome is not only one of over conditioned animals but is more typically associated with inadequate energy intake to support pregnancy requirements leading to body protein and fat mobilization. Blood chemistries provide insight into diagnosis and possibly may predict responsiveness to treatment and outcome. Early recognition of the disease with appropriate intervention is the best approach to minimizing the impact of this disease in the sheep flock or goat herd.

Metabolic Profiling in Ruminant Diagnostics.

A herd-based approach and interpretative perspective is necessary in using metabolic profile testing in contrast to individual animal disease diagnostics. Metabolic profile testing requires formulating a question to be answered, followed by the appropriate selection of animals for testing. A range of blood analytes and nutrients can be determined with newer biomarkers being developed. Sample collection and handling and herd-based reference criteria adjusted to time relative to parturition are critical for interpretation. The objective of this article is to review the concepts and practical applications of metabolic profile testing in ruminants.

Nonnutritional factors influencing response to the nutritional program.

In this article, the important role of the cow's environment is addressed, namely, the facilities that provide opportunities to eat, sleep, drink water, and socially interact. Research and anecdotal observation suggest that cow comfort is a critical factor to success of any nutritional program.

Transition cow nutrition and feeding management for disease prevention.

In this article, an overview is presented of nutrient modeling to define energy and protein requirements of the late pregnant cow, and metabolic relationships between fetus and cow as they relate to nutrient utilization and risk for postparturient disease are discussed. Recommendations for formulating dry cow diets are provided, with emphasis on opportunities to minimize variation and risk for postparturient disease events.

Higher whole-blood selenium is associated with improved immune responses in footrot-affected sheep.

We reported previously that sheep affected with footrot (FR) have lower whole-blood selenium (WB-Se) concentrations and that parenteral Se-supplementation in conjunction with routine control practices accelerates recovery from FR. The purpose of this follow-up study was to investigate the mechanisms by which Se facilitates recovery from FR. Sheep affected with FR (n = 38) were injected monthly for 15 months with either 5 mg Se (FR-Se) or saline (FR-Sal), whereas 19 healthy sheep received no treatment. Adaptive immune function was evaluated after 3 months of Se supplementation by immunizing all sheep with a novel protein, keyhole limpet hemocyanin (KLH). The antibody titer and delayed-type hypersensitivity (DTH) skin test to KLH were used to assess humoral immunity and cell-mediated immunity, respectively. Innate immunity was evaluated after 3 months of Se supplementation by measuring intradermal responses to histamine 30 min after injection compared to KLH and saline, and after 15 months of Se supplementation by isolating neutrophils and measuring their bacterial killing ability and relative abundance of mRNA for genes associated with neutrophil migration. Compared to healthy sheep, immune responses to a novel protein were suppressed in FR-affected sheep with smaller decreases in FR-affected sheep that received Se or had WB-Se concentrations above 250 ng/mL at the time of the immune assays. Neutrophil function was suppressed in FR-affected sheep, but was not changed by Se supplementation or WB-Se status. Sheep FR is associated with depressed immune responses to a novel protein, which may be partly restored by improving WB-Se status (> 250 ng/mL).

Nutritional diseases of llamas and alpacas.

Limited published reports of nutritional diseases affecting llamas and alpacas were found in a detailed review of relevant literature sources. Anecdotal clinical experiences and nutritional diseases that have been reported range from those diagnosed in common with other species to diseases having a presentation unique to camelids. Vitamin D-associated rickets and greater susceptibility to hepatic lipidosis and zinc deficiency are distinctive nutritional problems for llamas and alpacas. This article will review commonly encountered nutritional diseases, based on literature reports and clinical experience, in llamas and alpacas.

Nutritional requirements and assessing nutritional status in camelids.

It has been nearly 30 years since the first imported llamas and alpacas have been commercially raised in the United States. Nutritional requirements for these animals have not been well understood and most feeding practices were based on extrapolated and experiential information. Only recently has a National Research Council committee reviewed the available published information relative to nutrient requirements of llamas and alpacas. This article summarizes current nutrient requirement recommendations and provides some practical feeding recommendations and methods to assess nutritional status.

Vitamin D-responsive rickets in neonatal lambs.

An unusual clinical presentation of rickets in nursing lambs is described. Two sets of twin nursing lambs were presented for enlarged joints and mild angular deformity. Rickets was suspected, based on radiographic evidence. Vitamin D deficiency was determined to be the cause, based on serum concentration and response to therapy.

Dietary (n-3) fatty acids from menhaden fish oil alter plasma fatty acids and leukotriene B synthesis in healthy horses.

The study objective was to determine the effect of feeding corn oil or fish oil to horses on plasma fatty acid profiles and leukotriene B (LTB) synthesis by stimulated peripheral blood neutrophils. Two groups of horses (n = 5) were randomly assigned to diets supplemented with either 3.0% (by weight) corn oil or fish oil for a period of 14 weeks. The ratio of (n-6) to (n-3) fatty acids in oil supplements was 68.1:1 for corn oil and 0.12:1 for fish oil. Production of LTB4 and LTB, by peripheral blood neutrophils stimulated with calcium ionophore A23187 and plasma cholesterol, triacylglycerol, and alpha-tocopherol concentrations were measured. At 12 weeks, horses fed fish oil had increased plasma concentrations of eicosapentaenoic acid (27-fold; 8.5 versus 0.3 g/100 g fatty acids; P < .0001), docosahexaenoic acid (34-fold; 5.1 versus 0.1 g/100 g fatty acids; P < .0001), and arachidonic acid (8.3-fold; 4.1 versus 0.5 g/100 g fatty acids; P < .0001) compared with horses fed corn oil. Neutrophils from horses fed fish oil produced 78-fold (P = .01) more LTB5 and 9.5-fold (P = .003) more LTB4 compared with predietary levels, and 17.6-fold (P = .01) and 3.3-fold (P = .02), respectively, more than horses fed corn oil, and the ratio of LTB5 to LTB4 concentrations was 4.0-fold (P = .002) higher in horses fed fish oil. This study suggests that dietary polyunsaturated fatty acids modulate the leukotriene inflammatory response of horses. If the ratio of LTB5 to LTB4 concentrations is important in determining how inflammatory processes are mediated, then fish oil supplementation may have value in treatment of equine inflammatory diseases.

Effect of type of dietary polyunsaturated fatty acid supplement (corn oil or fish oil) on immune responses in healthy horses.

The objective of this study was to compare effects of dietary polyunsaturated fatty acid supplementation (corn oil or fish oil) on selected immune responses in normal horses. Two groups of horses (n = 5) were randomly assigned a dietary supplement with either 3.0% corn oil or fish oil for a period of 14 weeks. Plasma fatty acid profiles were monitored to ensure uptake of dietary fatty acids. Cell-mediated immunity was assessed by a delayed-type hypersensitivity (DTH) skin test to keyhole limpet hemocyanin (KLH), and humoral immunity was assessed by measuring antibody titers to KLH. Production of prostaglandin E2 (PGE2), expression of tumor necrosis factor-alpha (TNF-alpha), and phagocytosis of latex beads by bronchoalveolar lavage fluid (BALF) cells were also assessed. Lipopolysaccharide (LPS)-stimulated BALF cells from horses fed corn oil showed a higher production of PGE2 compared with those from horses fed fish oil at 6 and 12 weeks. Production of TNF-alpha by LPS-stimulated BALF cells was higher in both groups of horses at 6, 8, and 12 weeks compared with pretrial values, and phagocytic activity of BALF cells was higher at 8 and 12 weeks, however, there were no differences between the 2 groups of horses. The DTH skin test and antibody titers to KLH revealed no differences between horses fed corn or fish oil. Based on these studies, dietary polyunsaturated fatty acids modulate the inflammatory response of horses. Both fatty acid supplements increased production of the proinflammatory cytokine TNF-alpha, whereas only corn oil increased production of the proinflammatory eicosanoid PGE2 by LPS-stimulated BALF cells. It is possible that fish oil, because it did not increase production of PGE2, could have value in the treatment of equine recurrent airway obstruction or other equine inflammatory diseases.

Seasonal interaction of serum vitamin D concentration and bone density in alpacas.

OBJECTIVE: To evaluate temporal changes in bone mineral density associated with seasonal variation in serum vitamin D, calcium, and phosphorus concentrations in alpacas. ANIMALS: 5 healthy mature neutered male alpacas. PROCEDURE: Metacarpal bone mineral density was measured at 4 times during a year. Each time alpacas were weighed, blood was collected for determination of serum calcium, phosphorus, and vitamin D concentrations, and samples of feed were analyzed for nutrient content. Vitamin D status was determined by use of an assay that measured serum 25-hydroxycalciferol concentration. Effects of changes in serum vitamin D, calcium, and phosphorus concentration and body weight with season on bone mineral density were determined. RESULTS: Bone mineral density, body weight, and serum vitamin D and phosphorus concentrations varied with season. Bone mineral density, serum vitamin D concentration, and body weight also varied among individual alpacas. Serum vitamin D concentration was lower in January than the previous October and increased from May to the following September. The decrease in bone mineral density lagged behind the decrease in serum vitamin D concentration and was lower in May, compared with the previous October. Body weight was lower in May than the previous October or following September. Solar radiation was highest in July and lowest in December. CONCLUSIONS AND CLINICAL RELEVANCE: Seasonal changes in bone mineral density are associated with changes in serum vitamin D concentrations in alpacas. Changes in bone mineral density associated with a decline in serum vitamin D concentration may predispose some alpacas to developing fractures minimal trauma.