Influence of calcium chloride fed prepartum on severity of edema and lactational performance of dairy heifers

Graduate Student Literature Review: Udder edema in dairy cattle-A possible emerging animal welfare issue

Physiological udder edema is a noninfectious metabolic disorder in dairy cattle, which may be present in a high percentage of dairy cows. This review summarizes the factors associated with udder edema. They include genetics, nutrition, oxidative stress, and physiological changes in freshening heifers. Udder edema negatively affects the productive life of a dairy cow. Udder support structures may be broken down due to tissue damage. Swollen teats may become sensitive, which makes attaching the milking unit more difficult. The amount of milk produced is decreased due to fluid buildup in the tissue spaces. Risk of secondary diseases, such as mastitis or udder cleft dermatitis, is also increased. All of these elements have an economic impact on the dairy farmer, in both the short term and the long term. If severe, damage could lead to early culling. Some possible methods for managing udder edema include (1) providing a separate diet for late-gestation heifers to monitor anionic salt intake, (2) selecting for either genetic lines with lower milk production or a phenotypic reduction of udder edema, and (3) ensuring that adequate exogenous antioxidants, such as vitamin E, vitamin C, carotenoids, and flavonoids, are provided in the diet to mitigate oxidative stress. In conclusion, udder edema may be an emerging issue that has the potential to seriously affect dairy cow welfare. Many of the research studies are outdated, and research with modern dairy cows is needed. The development of a scientifically validated udder edema scoring system is also needed to assess the severity of udder edema.

Management of dry cows for the prevention of milk fever and other mineral disorders

Mineral disorders in dairy cattle typically occur soon after calving and are often specifically related to nutritional management during the late dry period. The incidence of hypocalcemia, hypophosphatemia, and hypomagnesemia can be minimized by proper diet formulation and good overall nutritional management in the dry period. The addition of anions to the diet during the late dry period may be of particular benefit for preventing hypocalcemia; however, supplementation with anions will reduce dry matter intake if feeding management is not excellent.

Calcium and vitamin D metabolism in the dairy cow

Most dairy cows experience some degree of hypocalcemia during the periparturient period. There is, however, a sub-group of dairy cows that experience a breakdown in their ability to maintain plasma calcium and, consequently, suffer from severe hypocalcemia. This condition is also known as milk fever and usually occurs in cows in their third or greater lactation. The precise metabolic lesions responsible for the onset of milk fever have not yet been defined. Research has shown that milk fever is not the result of inadequate production of calcitropic hormones (parathyroid hormone and 1,25-dihydroxyvitamin D), but rather is more likely a result of inadequate receptor numbers or receptor dysfunction in the target cell of these hormones. This report reviews vitamin D and calcium metabolism, giving emphasis to 1,25-dihydroxyvitamin D receptor regulation and function as related to the periparturient dairy cow. The report also focuses on providing insights into nutritional (anionic diets) and endocrine strategies that have proved useful in milk fever management.

Manipulation of dietary cation-anion difference on nutritionally related production diseases, productivity, and metabolic responses of dairy cows

Dietary cation-anion difference has been defined as milliequivalents of (Na+K)-(Cl+S) per kilogram of DM and has a direct impact on blood acid-base metabolism. As this difference decreases, one or more of the following blood parameters change: increased H+, decreased HCO3-, and decreased pH. These changes are accompanied by reduced urinary HCO3- excretion and pH as compensatory mechanisms. Although other minerals have an impact on acid-base metabolism, the four minerals used in dietary cation-anion difference have the greatest effect. Manipulation of acid-base balance can be used to manipulate other biological functions to benefit health and productivity of cows. Low cation-anion difference prepartum can mitigate hypocalcemia peripartum via increased urinary Ca, blood-ionized Ca, and responsiveness to Ca homeostatic hormones. These changes reduced the incidence of paresis and increased productivity by reducing the severity and length of hypocalcemia in all cows (periparturient), regardless of the occurrence of paresis. Reduced cation-anion differences prepartum have been related to a reduced severity of udder edema, likely related to increased renal loss of water and unchanged water intake. However, the effects on acid-base balance cannot be ruled out because of effects on biochemical and transport processes. Elevated cation-anion difference in lactation has been shown to increase DMI and production and to mitigate the effects of heat stress. Because production and heat stress are acidogenic, elevated cation-anion difference improves blood-buffering capacity to cope with H+. In heat stress, elevated water intake with elevated cation-anion difference cannot be ignored. Other diseases related to metabolic acid, such as laminitis and ketoacidosis, may be influenced by elevated cation-anion difference in lactation; however, research in these areas has not been forthcoming.

Evaluation of a system for rating edema in dairy cattle

Our objective was to evaluate a subjective edema rating system to quantitate edema severity. Edema was evaluated with 20 nulliparous Holstein heifers from 3 wk before their expected calving date until 3 wk postpartum. Severity of udder edema was evaluated independently daily by five people throughout the 68-d experiment; a 10-point rating system (0 = no edema, 10 = severe edema) was used. One of the people developing the scoring system served as the official scorer. The accuracy of the rating system, defined as the closeness of test evaluator scores to official scores, was highest for scores 2 to 8. The precision of the system, identified by the standard error of the mean, was similar for each score in the rating system. The largest disagreement between official and test evaluator scores was evident postpartum. The large number of defined points in this rating system and the similarity between official and test scores in this study indicate the usefulness of this tool to evaluate precisely the severity of edema in dairy cattle.