and K

and K.R.P.; methodology, R.S., C.D.K.B., D.T.H. an adequate amount of colostrum. Abstract The objective of this observational study was to estimate the incidence of inadequate transfer of passive immunity (ITPI) on five pasture-based dairy farms in South Australia. Heifer calf uptake of colostrum was evaluated within the first 1C7 days of age (= 2638) using a digital refractometer to estimate each calfs serum total protein concentration, as an indicator of colostrum uptake. Results of <51 g/L indicated inadequate transfer of passive immunity (ITPI). The data showed that the incidence of ITPI on the farms was 6.5%, 31.3%, 48.8%, 49.7% and 52.4%. The incidence of ITPI was NVP-LCQ195 calculated in relation to the age of the calf at testing and the breed of calf, and no significant differences were found. A significant difference was found in the incidence of ITPI when comparing the calfs first feed after separation from the dam (colostrum versus a colostrum-transition milk mixture). The farm with the lowest incidence of ITPI collected calves twice a day, measured colostrum quality on farm with a Brix refractometer and ensured that each calf received an appropriate amount of high-quality colostrum soon after collection. Further NVP-LCQ195 studies are required to establish the risk factors of ITPI in South Australian dairy heifers. Keywords: colostrum, failure of passive transfer, dairy cattle, Australia, refractometer 1. Introduction Cows have a cotyledonary synepitheliochorial placenta [1,2], which prevents immunoglobulins in the dams blood from entering the fetal circulation and results in calves being born virtually agammaglobulinaemic. Therefore, to obtain an effective immune response against pathogens in their first few weeks of life, neonatal calves rely on the absorption of maternal immunoglobulins as well as other immune-related proteins and cells from colostrum [3,4,5]. Calves that receive adequate amounts of good-quality colostrum within the first 24 h of birth will generally have better health and growth in the pre-weaning stage compared to calves with an inadequate uptake of colostrum [6,7,8,9,10]. The concept of adequate uptake of colostrum has historically focused on the immunological benefits of colostrum, primarily the immunoglobulin component that is transferred from colostrum into the calfs bloodstream (mainly immunoglobulin G (IgG) in cattle [10]). The absorption of maternal IgG from colostrum NVP-LCQ195 through the neonatal gut results in the transfer of passive immunity. The level of passive immunity acquired by the calf has been measured and estimated by various methods and, for each method, there has been a PSTPIP1 variety of suggested thresholds for determining whether a calf has received adequate immunity (Table 1). Serum has been the most common sampled tissue, usually in calves older than 24 h of age and less than seven days of age. Direct measures of IgG are generally considered to be the most accurate for estimating the transfer of passive immunity, but these tests are expensive, slow and only measure IgG. Alternate tests that indirectly estimate the uptake of IgG or other colostral components have also been used. For example, measuring serum total protein with a refractometer is a quick, cheap and reliable way to estimate the uptake NVP-LCQ195 of IgG, since most of the serum protein in young calves is IgG [11]. Table 1 Examples of different measures and estimates of transfer of passive immunity in calves from serum samples. Values below the thresholds are indicative of inadequate transfer of passive immunity (ITPI). process, which results in immunity [17]. Secondly, terms using the word failure imply that there has been transfer of passive immunity, whereas, in most cases, there has been some transfer of passive immunity, but just not a sufficient amount to provide satisfactory protection against morbidity and/or mortality. Other authors have addressed these inaccuracies by referring to the occurrence as inadequate transfer of colostral immunoglobulins [33] or inadequate transfer of passive immunity [34]. The later term is favored herein, as it recognizes.