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

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 standards 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.

Preweaned heifer management on US dairy operations: Part II. Factors associated with colostrum quality and passive transfer status of dairy heifer calves.

Passive transfer of immunity is essential for the short- and long-term health of dairy calves. The objective of this study was to evaluate factors associated with colostrum quality and passive transfer status of US heifer calves. This study included 104 operations in 13 states that participated in the calf component of the National Animal Health Monitoring System's Dairy 2014 study. This 18-mo longitudinal study included 1,972 Holstein heifer calves from birth to weaning. Multivariable mixed linear regression models were selected using backward elimination model selection after univariate screening to determine which factors were associated with colostrum IgG and serum IgG concentrations. The mean colostrum IgG concentration was 74.4 g/L with 77.4% of colostrum samples having IgG concentrations >50 g/L. The final model for colostrum IgG included colostrum source and a categorized temperature-humidity index value (cTHI) for the month before calving. Mean colostrum IgG concentrations were highest for dams in third and higher lactations (84.7 g/L) and lowest for commercial colostrum replacers (40.3 g/L). Colostrum IgG concentrations were highest for cTHI ≥70 (72.6 g/L) and lowest for cTHI <40 (64.2 g/L). The mean serum IgG concentration was 21.6 g/L, with 73.3% of calves having serum IgG concentrations >15 g/L. The final model for serum IgG concentration included region, heat treatment of colostrum, colostrum source, timing to first feeding, volume of colostrum fed in the first 24 h, age of the calf at blood sampling, and colostrum IgG concentration. Mean serum IgG concentrations were highest for calves that received colostrum from first-lactation dams (25.7 g/L) and lowest for calves fed commercial colostrum replacer (16.6 g/L). Serum IgG concentrations were higher for calves fed heat-treated colostrum (24.4 g/L) than for calves fed untreated colostrum (20.5 g/L). Serum IgG concentration was positively associated with the volume of colostrum fed in the first 24 h and colostrum IgG concentration, and negatively associated with the number of hours from birth to colostrum feeding and age (days) at blood collection. Dairy producers should be encouraged to measure the quality of colostrum before administering it to calves and to measure serum IgG or a proxy such as serum total protein or Brix to evaluate passive immunity and colostrum management programs.

Preweaned heifer management on US dairy operations: Part I. Descriptive characteristics of preweaned heifer raising practices.

The objective of this study was to describe preweaned dairy heifer calf management practices on dairy operations across the United States that were used to analyze factors associated with colostrum quality and passive transfer, Cryptosporidium and Giardia, morbidity and mortality, and average daily gain. This study included 104 dairy operations in 13 states that participated in the National Animal Health Monitoring System's Dairy 2014 calf component study. This 18-mo longitudinal study focused on dairy heifer calves from birth to weaning, and data were collected on 2,545 heifer calves. Descriptive statistics were generated regarding colostrum feeding, preweaning housing, milk feeding and consumption, growth, morbidity and mortality, and weaning practices. The majority of calves enrolled were Holsteins (89.4%). Over half the calves (63.2%) enrolled in the study received the majority of their colostrum via bottle; however, 22.1% of calves from 51.0% of operations received colostrum via suckling from their dams. For all calves, the mean time to the first colostrum feeding was 2.8 h, and the average amount of colostrum at the first feeding was 2.9 L, with 4.5 L provided in the first 24 h. The mean serum IgG of all calves was 21.7 g/L; however, 76.0% of operations had at least 1 calf with failure of passive transfer of immunity with a serum IgG below 10 g/L. The majority of calves in the study were housed individually (86.6%). Nonetheless, 20.2% of operations housed some calves in groups, representing 13.4% of all calves. Approximately one-half of the calves in the study (52.3%) were dehorned or disbudded during the preweaning period, with only 27.8% of these calves receiving analgesics or anesthetics during the procedure. Whole or waste milk was the liquid diet type fed to 40.1% of calves, and milk replacer was fed to 34.8% of calves. A combination of milk and milk replacer was fed to 25.1% of calves. Calves, on average, were fed 2.6 L per feeding and fed 2.6 times/d, resulting in a total of 5.6 L of liquid diet fed per day. The mean average daily gain for all calves enrolled in the study was 0.7 kg/d. Fecal samples were collected and almost all operations had at least 1 calf positive for Cryptosporidium (94.2%) or Giardia (99.0%), and 84.6% of operations had calves that tested positive for both Cryptosporidium and Giardia. Over one-third of calves (38.1%) had at least one morbidity event during the preweaning period and the mortality rate was 5.0%. The mean age at weaning was 65.7 d. This study provides an update on dairy heifer raising practices in the United States.

The effect of vitamin E supplementation on discoloration of injection-site lesions in retail cuts and the greening reaction observed in injection-site lesions in muscles of the chuck.

Concern has been raised about green discoloration of injection-site lesions in chuck muscles in modified-atmosphere packages. Objectives were: 1) to recreate green lesions, 2) to compare the severity of discoloration of injection-site lesions in chucks from carcasses of control or vitamin E-supplemented steers, and 3) to identify pigment(s) responsible for discoloration via in vitro color reactions. In Exp. 1, 23 steers (BW = 415 kg; 37 d before harvest) were injected with one of 12 pharmaceuticals, following label directions for route and dose, with the exception of a 5-mL maximum dose, to identify a product that could result in discoloration. Two vaccines (Products A and B) resulted in greening. In Exp. 2, 50 steers were injected (i.m.) with Product A and assigned to the control or vitamin E (1,000 IU/steer daily for 60 d) group. After retail display, 80 and 72% of steaks from the control and treatment groups, respectively, were discolored. Although vitamin E did not reduce (P = 0.53) greening, there was a trend (P = 0.10) toward delay discoloration of lesions from the treatment group. In Phase I of Exp. 3, pigments extracted from green lesions obtained from Exp. 2 were compared with solutions, exposed to a high partial pressure of oxygen (ppO), of myoglobin (Mb), copper sulfate, hydrogen peroxide (H2O2), vaccine, and aluminum hydroxide either alone or in combination. In Phase II of Exp. 3, solutions of two or more of Mb, Cu, sodium sulfide, sodium sulfite, sodium sulfate (Na2SO4), and H2O2 were made at pH 7.2 or 5.5 and exposed to low or high ppO. Normal muscle tissue displayed a 3.2 and 56.7% decrease in absorbance/microg of protein as wavelength changed from 654 to 656 nm and 656 to 658 nm, respectively. Pigments from control and treatment group green tissue displayed a 164.5 and 621.3% increase, respectively, in absorbance/microg of protein as wavelength changed from 654 to 656 nm. As wavelength changed from 656 to 658 nm, the absorbance/microg of protein for control and treatment group lesions decreased by 75 and 109%, respectively. The Mb+Cu+Na2SO4 solution, at pH 5.5 and high ppO, exhibited similar absorbance trends as green lesions indicating that greening may result from a Mb, Cu, and Na2SO4 interaction. Results indicated that greening varies with pharmaceuticals and oxidation of tissue cannot be controlled with vitamin E supplementation. Research on the causative agents of green discoloration, with an emphasis on compounds containing sulfate or Cu, is needed.

Serum copper concentrations in beef cows and heifers.

OBJECTIVE: To characterize serum copper status of cows and heifers in beef cow-calf herds throughout the United States and to evaluate use of copper supplements in those herds. DESIGN: Cross-sectional survey. ANIMALS: 2,007 cows and heifers from 256 herds in 18 states. PROCEDURES: Producers participating in a health and management survey conducted as part of the National Animal Health Monitoring System voluntarily allowed serum samples to be obtained from cows and heifers for determination of copper concentration. Results were categorized as deficient, marginally deficient, or adequate. The proportion of cattle and herds (on the basis of mean value of the tested cattle) in each category was determined. Copper concentrations were compared between herds that reportedly used copper supplements and those that did not. RESULTS: Overall, 34 of 2,007 (1.7%) cows and heifers were deficient in copper, and 781 (38.9%) were marginally deficient. In each region, at least a third of the cattle were deficient or marginally deficient. For herds, 92 of 256 (35.9%) were marginally deficient, and 22 (0.8%) were deficient. Approximately half of the producers reported use of copper supplements, but a sizeable proportion of those producers' cattle and herds were classified as marginally deficient or deficient. CONCLUSIONS AND CLINICAL RELEVANCE: Copper deficiency is not restricted to a single geographic region of the United States. Copper deficiency can persist despite reported use of supplements by producers. Veterinarians dealing with beef cow-calf herds that have problems consistent with copper deficiency should not rule out copper deficiency solely on the basis of geographic region or reported use of copper supplements for the herd.

Treatment of neonatal calf diarrhea with an oral electrolyte solution supplemented with psyllium mucilloid.

Dairy calves under 14 days of age with naturally occurring, uncomplicated diarrhea were treated for 3 days with a hypertonic oral electrolyte solution with (n = 15) or without (n = 12) psyllium. Clinical response and clinical pathology data were compared between the 2 groups. Glucose absorption was evaluated on days 1 and 3 by measurement of plasma glucose and lactate and serum insulin concentrations for 4 hours after formula administration. On day 1, glucose, lactate, and insulin concentrations were lower in psyllium-fed calves than in control calves, with significant differences noted in glucose and lactate concentrations at several time points (P < 0.05). Plasma lactate concentrations were higher at several times in both treatment groups on day 3 than on day 1 (P < 0.05). Fecal consistency was markedly different in psyllium-fed calves as compared with control calves within 24 hours of psyllium supplementation. Fecal percent dry matter content was lower in psyllium-fed calves than in control calves at least once a day during supplementation and on day 3 compared with day 0 in the psyllium-fed calves (P < 0.05). There were no significant differences in clinical performance scores, hydration status, arterial blood gas, serum anion gap, electrolyte, or total CO2 concentrations. Addition of psyllium to an oral electrolyte solution resulted in immediate alterations in glucose absorption without impairing rehydration in diarrheic calves, but differences were transient and did not affect clinical outcome.

Gravel obstruction in the abomasum or duodenum of two cows.

Two Holstein cows from dry lot dairies were evaluated because of clinical signs of depression, anorexia, and decreased milk production. Bilateral abdominal distention and decreased fecal output were found on physical examination. Results of serum biochemical analyses indicated that the cows had severe hypochloremic, hypokalemic metabolic alkalosis. On the basis of physical examination and laboratory findings, an obstruction of the abomasum or cranial portion of the small intestine was suspected in these cows and abdominal exploratory surgery was performed. A mass of gravel was found in the pyloric antrum of the abomasum of 1 cow and the descending duodenum of the other cow. The duodenal obstruction was removed by enterotomy, and the pyloric mass was manually reduced during surgery. The cows were treated with antibiotics and isotonic saline solution (NaCl) supplemented with potassium chloride and recovered quickly after surgery.

Urinary indices of renal function in sheep with induced aminoglycoside nephrotoxicosis.

Aminoglycoside nephrotoxicosis (AGNT) was induced in ewes by daily SC administration of gentamicin. Changes in urinary indices of renal function during the development of AGNT are reported. Measurements from timed, volume-measured urine samples were made on days 0, 7, and 8 and included creatinine clearance, total excretion (TE) rates of electrolytes (Na, K, Cl, P) and urine volume. Measurements from free-catch urine samples (without volume measurement) were made daily and included fractional excretion (FE) rate of electrolytes, urine osmolality, and urine-to-serum osmolality and urine-to-serum creatinine ratios. With the onset of AGNT, FE rates of Na, K, Cl, and P- increased many fold above baseline values (200x, 4 to 5x, 6 to 9x, and 70 to 95x, respectively, on days 7 and 8), indicating decreased tubular reabsorption or increased tubular secretion. The increased FE rates were not representative of increases in total electrolyte excretion rates. The total excretion of Na (TENa) was mildly increased, TEK was decreased, TECl was unchanged, and TEP was significantly increased on days 7 and 8. Abnormal urinalysis results, glucosuria, and increased FEP preceded appreciable increase in serum creatinine concentration. Other abnormal urinary indices of renal function coincided with or followed the increase in serum creatinine concentration. Urinary indices may help characterize renal function associated with the disease state, but did not provide early indication of AGNT.