Effects of elevated iodine in milk replacer on calf performance

Technical Validation of Ultrasound Assessment of the Thyroid Gland in Cattle

Little is known about thyroid diseases in ruminants, probably due to the lack of diagnosis techniques developed in this species. However, thyroid ultrasound (TU) is widely used in human and in companion animal's medicine. It is a cheap and non-invasive examination, which allows for the identification of thyroid structures or diffuse diseases. The aim of this study was to evaluate the accuracy of TU in five calves and five cows through inter- and intra-observer repeatability. The size of the thyroid gland was measured from three views: left sagittal, right sagittal and transverse; nine measurements per view. The intra-observer coefficient was calculated for each observer. For the inter-observer, the first observer was a board-certified imagist (European College of Veterinary Diagnostic Imaging diplomate), the second was a board-certified specialist in bovine and herd management (European College of Bovine Health Managementdiplomate) and the third was an in-trained veterinarian for the TU. They each scanned the thyroid gland successively, following the same method. The intra-observer variabilities for observers 1, 2 and 3 were 8.22%, 5.53%, 5.38%, and 7.18%, 8.65% and 6.36%, respectively, for calves and cows. The inter-observer variability for calves was 10.4% and for cows, 11.8%. This study confirms the feasibility of repeatable intra- and inter-observer TU-estimated measurements in cattle.

A 100-Year Review: Calf nutrition and management

The first calf paper, published in the May 1919 issue of the Journal of Dairy Science (JDS), described factors affecting birth body weight of different breeds of calves. Other studies were done on nonmilk ingredients, growth charts were developed, and early weaning was followed to conserve milk fed to calves. Calf papers did not report use of statistics to control or record variation or to determine whether treatment means were different. Many experiments were more observational than comparative. Typically fewer than 5 calves, and sometimes 1 or 2 calves, were used per treatment. During the next 20 yr, calf studies increased and included colostrum feeding, milk and milk replacer feeding, minerals and vitamins, and fats and oils. Many concepts fundamental to current knowledge and understanding of digestion, rumen development, and milk replacer formulation were developed during this period. In addition, the concept of using antibiotic growth promoters in dairy calf diets was first evaluated and developed during the 1950s. During the 20-yr period of January 1957 through December 1976, a large number of universities in the United States and 1 in Canada contributed almost 150 papers on a variety of calf-related topics. These topics included genetics, physiology of the calf, review of calf immunity, antibiotic feeding, and milk replacer ingredients. This became the golden era of calf rumen development studies, which also engendered studies of calf starter rations and ingredients. A classic review of management, feeding, and housing studies summarized research related to calf feeding and management systems up to that point with an emphasis on maintaining calf growth and health while reducing labor and feed costs. It was also during this period that metric measurements replaced English units. In the 20-yr period from 1977 to 1996, more than 400 articles on calf nutrition and management were published in JDS. With the growing research interest in calves, a paper outlining standardized procedures for conducting and reporting data from calf experiments was first published. A very active area of calf nutrition research from the late 1970s to the mid 1980s was colostrum quality, feeding, and preservation; more than 60 such research articles were published in the journal during this time. Various nonmilk protein sources were evaluated. Extensive studies were done evaluating trace and major mineral requirements in calves along with some vitamin studies. Throughout the 1970s, 1980s, and 1990s, the primary objective of most calf research was how to wean healthy, adequately grown calves at an early age-generally less than 30 d of age. This program was reviewed in a 1979 publication. Research on calf starter ingredients, nutrient composition, and additives was minimal in the 1980s and 1990s given the importance of starter intake to the success of early weaning, but the role of water intake in starter intake and growth was established. Research on issues with calves continued to increase during the last 20-yr period as evidenced by publication of more than 580 articles in JDS as well as many more in other refereed journals. In addition to papers contributed by several universities in the United States and Canada, the number of papers authored by scientists at universities and institutes in other countries increased dramatically during this period. Factors influencing colostral antibody absorption, heat treatment of colostrum, and efficacy of colostrum supplements and replacers were reported. Most studies in this period related to nutrition. Studies were published supporting greater neonatal growth rates from feeding more milk replacer but with a higher crude protein content than traditional. Protein energy effects on growth and body composition were evaluated in concert with greater growth rates. Milk and nonmilk protein sources in milk replacers along with AA supplementation were evaluated. Limited studies were done with fat sources and fatty acid supplementation along with trace minerals and fat-soluble vitamins. Waste milk feeding and heat treatment became more prevalent. Studies established starter ingredient palatability and use of forage when fed with pelleted starters. With the advent of automatic milk and milk replacer feeders, factors influencing how and when to wean were established. Research programs established factors affecting calf behavior and welfare. Several databases were evaluated along with various published studies, and established calf growth during the first 2 mo was subsequently reflected in first- and later-lactation milk production of those calves. A new area of calf research that emerged from 1997 on was the effects of maternal environment and nutrition on calf health, growth, and future productivity. From a mechanistic standpoint, the field of epigenetics seems likely to explain many of these phenomena. Some possibilities for future calf nutrition and management were elaborated.

Tolerance of the preruminant calf for excess manganese or zinc in milk replacer

In two experiments, calves were fed milk replacer containing 40, 200, 500, 1000, or 5000 ppm Mn or 40, 200, 500, 700, or 1000 ppm Zn in DM, from 3 to 38 d of age, to estimate the minimum toxic concentrations of Mn and Zn. Starting at 1000 ppm Mn, weight gains and feed efficiencies were decreased slightly; none of the calves fed 5000 ppm Mn survived the 5-wk experiment. Liver and bile showed the largest increases in Mn concentration. In the Zn experiment, only at 700 and 1000 ppm Zn were weight gains, DM intake, and feed efficiency reduced. Largest Zn increases were in liver, kidney, and plasma. Thus, performance of the preruminant calves was not affected adversely by 500 ppm Mn or 500 ppm Zn in milk replacer, concentrations that are markedly higher than the NRC recommendations of 40 ppm Mn and 40 ppm Zn. However, Mn and Zn concentrations increased in some tissues, and toxicities might have arisen if the trial had been continued. Evidence was not obtained indicating that the calf benefits from Mn or Zn intakes above the NRC recommendations.

Lipid compositional changes in calves fed excess iodine

Calves were fed milk replacer containing .57, 10, or 200 ppm iodine (from ethylenediaminedihydriodide) to determine the effects of excess dietary iodine on composition of lipids in blood plasma, liver, and heart. High iodine intakes had no effect on plasma total lipids or lipid classes, but caused lipid class concentration changes in liver and heart. Both 10 and 200 ppm iodine increased concentration of liver phosphatidylethanolamine and heart phosphatidylcholine, cholesterol, and total lipids, and the 200 ppm intake also increased concentration of liver phosphatidylcholine, total lipids, and heart phosphatidylethanolamine. Both iodine treatments tended to increase all the other minor lipid classes in liver and heart as well. Both 10 and 200 ppm iodine treatments increased some of the n-3 polyunsaturated fatty acids in the major phospholipids of plasma, liver, and heart. For the preruminant calf, liver and heart may be more useful than blood plasma for indicating excess iodine effects on lipid metabolism.