Consensus recommendations on calf- and herd-level passive immunity in dairy calves in the United States

Abstract

Passive immunity in calves is evaluated or quantified by measuring serum or plasma IgG or serum total protein within the first 7 d of age. While these measurements inform about circulating concentrations of this important protein, they are also a proxy for evaluating all of the additional benefits of colostral ingestion. The current individual calf standard for categorizing dairy calves with successful passive transfer or failure of passive transfer of immunity are based on serum IgG concentrations of ≥10 and <10 g/L, respectively. This cutoff was based on higher mortality rates in calves with serum IgG <10 g/L. Mortality rates have decreased since 1991, but the percentage of calves with morbidity events has not changed over the same time period. Almost 90% of calves sampled in the USDA National Animal Health Monitoring System's Dairy 2014 study had successful passive immunity based on the dichotomous standard. Based on these observations, a group of calf experts were assembled to evaluate current data and determine if changes to the passive immunity stan-dards were necessary to reduce morbidity and possibly mortality. In addition to the USDA National Animal Health Monitoring System's Dairy 2014 study, other peer-reviewed publications and personal experience were used to identify and evaluate potential standards. Four options were evaluated based on the observed statistical differences between categories. The proposed standard includes 4 serum IgG categories: excellent, good, fair, and poor with serum IgG levels of ≥25.0, 18.0-24.9, 10.0-17.9, and <10 g/L, respectively. At the herd level, we propose an achievable standard of >40, 30, 20, and <10% of calves in the excellent, good, fair, and poor categories, respectively. Because serum IgG concentrations are not practical for on-farm implementation, we provide corresponding serum total protein and %Brix values for use on farm. With one-third of heifer calves in 2014 already meeting the goal of ≥25 g/L serum IgG at 24 h of life, this achievable standard will require more refinement of colostrum management programs on many dairy farms. Implementation of the proposed standard should further reduce the risk of both mortality and morbidity in preweaned dairy calves, improving overall calf health and welfare.

Evaluation of 3 refractometers to determine transfer of passive immunity in neonatal beef calves

“…Even in dairy calves, no agreement on the most appropriate STP thresholds has been reached, with recently suggested optimal thresholds ranging from 5.1 to 5.8 g/L. 9,[26][27][28][29][30] We acknowledge the limited usefulness of our proposed thresholds for detection of IgG <10 g/L in populations similar to ours. As shown in 31,32 , and also reflects the generally high average colostral IgG concentration in western Canadian beef cows.…”

Thermoregulatory Responses and Performance of Dairy Calves Fed Different Amounts of Colostrum

“…Thus, calves that received 15% or 20% BW of colostrum had higher concentrations of IgG, both at the beginning and during the cold challenge. If the more recent recommendation of the TSP cut point is applied [4], we could consider the PIT to be excellent since all calves present TSP > 6.2 g/dL. That was unexpected since feeding only 10% of BW as colostrum to the newborn could increase the proportion of calves with lower PST concentrations.…”

“…According to Osaka et al [2], the apparent efficiency of absorption (AEA) of IgG declines by less than 0.3%/h from calving to 12 h after birth and 2.5%/h from 12 to at least 18 h after birth. Feeding calves with higher volumes of colostrum during the first hours of life promotes optimum growth, reduces veterinarian and medical costs, and increases future milk production [3][4][5].…”

“…Godden [1] recommended feeding colostrum at 10% of BW within 6 h after birth. More recently, Lombard et al [4] have reached a consensus recommendation of an additional feeding of 5% of BW within 6 h after the first feeding, resulting in a total of 15% of BW. However, recommendations for colostrum feeding have been based mainly on the success of PIT and decreased morbidity and mortality, regardless of the requirement to increase the calf's tolerance to cold exposure.…”

Parenteral Antimicrobial Treatment Diminishes Fecal Bifidobacterium Quantity but Has No Impact on Health in Neonatal Dairy Calves: Data From a Field Trial

“…Median P2 weights tended to be lower for calves at E1 classified as sick relative to healthy calves although there was considerable overlap in the range of weights within the IQR. Median TSP values across the groups ranged from 5.9 to 6.3 g/dl and would be classified as good to excellent based on recent published recommendations (25). We used the farm level TSP distribution to create categories for subsequent analyses.…”