Association between hyperketolactia and production in early-lactating dairy cows.

Study aims were to investigate associations of hyperketolactia (HYKL) status of Holstein dairy cows between 6 and 60 d in milk (DIM), defined by milk acetone (mACE) and ß-hydroxybutyrate (mBHB) content, with daily milk yield and composition. Milk samples (∼5.0 million) were collected over a 5-yr period (2014-2019) within the milk recording system in Poland. Concentrations of mACE and mBHB determined by Fourier-transform infrared spectroscopy were used to categorize samples into 4 ketolactia groups. Based on threshold values of ≥0.15 mmol/L mACE and ≥0.10 mmol/L mBHB, ketolactia groups were normoketolactia (NKL; mACE <0.15 mmol/L and mBHB <0.10 mmol/L), BHB hyperketolactia (HYKLBHB; mACE <0.15 mmol/L and mBHB ≥0.10 mmol/L), ACE hyperketolactia (HYKLACE; mACE ≥0.15 mmol/L and mBHB <0.10 mmol/L), and ACE and BHB hyperketolactia (HYKLACEBHB; mACE ≥0.15 mmol/L and mBHB ≥0.10 mmol/L). To investigate ketolactia association with production outcomes, a linear model was developed, including ketolactia group, DIM, parity, their interactions, year-season as fixed effects, and random effects of herd and cow. Among all milk samples, 31.2% were classified as HYKL, and of these, 52.6%, 39.6%, and 7.8% were HYKLACEBHB, HYKLBHB, and HYKLACE, respectively. Ketolactia groups differed for all traits studied in all parities and DIM. Among HYKL groups, lowest milk yield was found in HYKLACEBHB cows, except for 6 to 30 DIM in first- and second-lactation cows. Milk yield of HYKLBHB cows was higher than that of NKL cows until 20 to 30 DIM, and then it was lower than NKL cows. Milk yield of HYKLACE cows was mostly lower than NKL cows. Energy-corrected milk (ECM) yield of HYKLACEBHB cows was higher than that of NKL cows until 30 to 35 DIM for second lactation and third lactation or greater, and in the whole study period for first lactation. The yield of ECM for HYKLBHB cows was mostly higher than that of NKL cows, whereas HYKLACE cows had higher ECM than NKL cows until 15 to 25 DIM and then was lower for the HYKLACE group. Milk composition differed among HYKL groups. Highest milk fat (MF) and lowest milk lactose (ML) contents were observed in HYKLACEBHB cows. Cows in HYKLACEBHB and HYKLBHB groups had higher MF and lower milk protein (MP; except in 6-8 DIM in first lactation) and ML content than NKL cows. Milk fat content was higher in HYKLACE than NKL cows in first lactation and during the first 30 to 40 DIM in older cows. Lactose content was lower in HYKLACE than in NKL cows within 30 to 40 DIM; afterward it was higher in NKL cows. Lower MP content was found in HYKLACE than in NKL cows, except during 6 to 9 DIM for cows in first lactation and third lactation or greater. In conclusion, HYKL is associated with altered milk production in all parities, but a range of these negative relations depends on ketone status addressing both ACE and BHB contents. Further research is needed to ascertain underpinning biochemical defects of HYKL from elevated ACE, alone or in combination with BHB, during early lactation.

Characterization of ketolactia in dairy cows during early lactation.

Fourier transform infrared spectroscopy (FTIR) allows for the determination of milk acetone (mACE) and ß-hydroxybutyrate (mBHB) concentrations, providing a potential herd monitoring tool for hyperketolactia, defined as elevated milk ketone bodies. The study aim was to characterize mACE and mBHB concentration dynamics during early lactation in Polish Holstein-Friesian cows. Milk samples (n = 3,867,390) were collected within 6 to 60 days in milk (DIM) over a 4-yr period (April 1, 2013 to March 31, 2017) from approximately 21,300 dairy herds (average 38.7 cows/herd). Fixed effects of parity, DIM, and their interaction on mACE and mBHB concentrations were determined using a mixed model with a herd-year-season fixed effect and random cow effect. Published hyperketolactic mACE (≥0.15 mmol/L) and mBHB (≥0.10 mmol/L) threshold concentrations were used to classify study milk samples into ketolactia groups of normal (mACE <0.15 mmol/L and mBHB <0.10 mmol/L) and hyperketolactic (HYKL; either mACE ≥0.15 mmol/L or mBHB ≥0.10 mmol/L). Additionally, HYKL samples were categorized into subpopulations as having elevated mBHB and mACE (HYKLACEBHB, mACE ≥0.15 mmol/L and mBHB ≥0.10 mmol/L), only elevated mBHB (HYKLBHB; mACE <0.15 mmol/L and mBHB ≥0.10 mmol/L), or only elevated mACE (HYKLACE; mACE ≥0.15 mmol/L and mBHB <0.10 mmol/L). Effects of parity, DIM, ketolactia group or subpopulation, and their interactions on mACE and mBHB concentrations were also determined using the mixed model that included ketolactia group or subpopulation as an independent variable. Across all data, mACE and mBHB concentrations were influenced by effects of parity, DIM, and their interaction as well as parity, DIM, ketolactia group or subpopulation, and their interactions. For all samples, mACE and mBHB concentrations decreased with increasing DIM, with mACE concentration declining more rapidly compared with mBHB. In the data set, 68% and 32% of all samples were defined as normal or HYKL, respectively. Among HYKL samples, mACE was elevated soon after calving and declined over time. In contrast, mBHB started lower after calving and increased reaching peak concentrations around 30 DIM, and then decreased. Within HYKL samples, 50.8, 41.3, and 7.9% were categorized as HYKLACEBHB, HYKLBHB, and HYKLACE respectively. Between 6 and 21 DIM, 11.3% of HYKL were classified as HYKLACE. Primiparous cows had greater (14.8%) HYKLACE samples in this time period. In conclusion, this study has characterized mACE and mBHB concentrations during early lactation and determined effects of parity, DIM, and their interaction. Using published criteria interpreting mACE and mBHB concentrations, it was intriguing to identify a unique population of samples having elevated mACE without mBHB in early lactation, especially in primiparous cows. Further research is needed to determine if this sample population represents an unhealthy metabolic status that adversely affects cow health and performance.

Efficacy of on-farm use of ultraviolet light for inactivation of bacteria in milk for calves.

Ultraviolet light is being employed for bacterial inactivation in milk for calves; however, limited evidence is available to support the claim that UV light effectively inactivates bacteria found in milk. Thus, the objective of this observational study was to investigate the efficacy of on-farm UV light treatment in reducing bacteria populations in waste milk used for feeding calves. Samples of nonsaleable milk were collected from 9 Pennsylvania herds, twice daily for 15 d, both before and after UV light treatment (n=60 samples per farm), and analyzed for standard plate count, coliforms, noncoliform, gram-negative bacteria, environmental and contagious streptococci, coagulase-negative staphylococci, Streptococcus agalactiae, Staphylococcus aureus count, and total solids percentage, and log reduction and percentage log reduction were calculated. Data were analyzed using the mixed procedure in SAS. In all bacteria types, samples collected after UV treatment contained significantly fewer bacteria compared with samples collected before UV treatment. Weighted least squares means for log reduction (percentage log reduction) were 1.34 (29%), 1.27 (58%), 1.48 (53%), 1.85 (55%), 1.37 (72%), 1.92 (63%), 1.07 (33%), and 1.67 (82%) for standard plate count, coliforms, noncoliform, gram-negative bacteria, environmental and contagious streptococci, Strep. agalactiae, coagulase-negative staphylococci, and Staph. aureus, respectively. A percentage log reduction greater than 50% was achieved in 6 of 8 bacteria types, and 43 and 94% of samples collected after UV treatment met recommended bacterial standards for milk for feeding calves. Based on these results, UV light treatment may be effective for some, but not all bacteria types found in nonsaleable waste milk. Thus, farmers should take into account the bacteria types that may need to be reduced when considering the purchase of a UV-treatment system.

Effect of parenteral selenium administration to sheep on prevalence and recovery from footrot.

BACKGROUND: Insufficient intake of selenium (Se) is common in many regions, and can contribute to increased susceptibility to and prolonged recovery from infectious diseases. OBJECTIVE: To determine the effect of Se administration in decreasing the severity and prevalence of footrot in sheep. ANIMALS: Thirty-eight footrot-affected and 19 nonaffected sheep from a commercial flock of known high incidence of footrot. METHODS: Placebo-controlled, prospective, 15-month clinical trial. Footrot-affected sheep were randomly assigned into 2 groups (n = 19) and injected with either 5 mg Se (footrot [FR]-Se) or saline (FR-Sal) at 1-month intervals for the duration of the study. Unaffected sheep (controls) received no treatment. Sheep feet were examined, trimmed, and scored for footrot with a scale of 0 (no footrot) to 4 (extensive) at 0, 3, 6, 9, and 15 months. Sheep were also bled at time 0 and then at 3, 6, and 15 months to assess whole blood Se concentrations. RESULTS: At time 0, control sheep (255 +/- 11 ng/mL) had higher (P < .05) whole blood Se concentrations compared with FR-Se (205 +/- 12 ng/mL) and FR-Sal (211 +/- 14 ng/mL) sheep. By 6 months, FR-Se sheep (317 +/- 9 ng/mL) had whole blood Se concentrations greater (P < .05) than both control (281 +/- 14 ng/mL) and FR-Sal (277 +/- 16 ng/mL) sheep. FR-Se ewes showed a faster decline in highest lesion score at 3 (P= .012) and 6 (P= .0036) months, and a greater decrease in the number of feet with foot score >0 at 6 (P= .020) months compared with FR-Sal ewes. Sheep with blood Se concentrations <300 ng/mL were at 3.5 times greater risk (1.1-12.1 confidence interval, odds ratio) for FR, although this relationship was only significant (P= .04) at 6 months of the study. CONCLUSIONS AND CLINICAL IMPORTANCE: In sheep with footrot, improved Se status in conjunction with routine control practices result in more rapid improvement of foot lesions.

Effect of nutrition on reproduction in llamas and alpacas.

The role of nutrition, especially the role of energy and protein status, on reproductive performance of production animals has been well documented. Comparatively, there is a true paucity of literature regarding nutritional mediation of reproductive performance in llamas and alpacas. Following seasonal patterns of feed availability in South America, adverse effects of nutritional deprivation on reproductive performance are well recognized, suggesting similar nutrition-reproduction interrelationships. Camelids, with their unique metabolism, may have some peculiar interrelationships between reproduction and protein and phosphorus nutrition. This presentation will review basic issues of energy and protein nutrition relative to reproductive performance in llamas and alpacas, based primarily on hypotheses and extrapolation from other species. Opportunities for research on this topic will be discussed, including preliminary data from current research.

Indicators of dairy cow transition risks: Metabolic profiling revisited.

Periparturient disease conditions affecting transition dairy cows have been recognized as a critical contributor to impaired dairy performance and have become a focal point of herd diagnostic investigations. Over the past 40 years use of blood sampling in the form of metabolic profiling has been applied to herd diagnostics with mixed impressions of diagnostic robustness. Research has greatly increased our understanding of underpinning mechanisms related to cow biology, management, environment and their interactions responsible for peripartum diseases. Elevated ß-hydroxybutyrate (BHB) concentration (> 1.2 mmol/l) within 7-10 days following calving identifies high risk cows for therapeutic intervention. Herd evaluations with 15-25% of first week fresh cows with elevated BHB indicates significant disease risk and productive losses. Elevated peripartal serum nonesterified fatty acids (NEFA) also indicate increased disease risk. This review discusses documented (BHB, NEFA) and other potential analytes using individual or pooled samples useful for disease risk assessment or nutritional status and their application in risk-based or herd screening methods of herd metabolic profiling diagnostics. A pooled sample approach modified from the original Compton Metabolic Profile allows for more economic assessment of multiple analytes, though interpretation and herd-size application may be limited. Pooled samples between 5 and 10 individuals accurately represent arithmetic means of individuals. Most importantly metabolic profiles must be used in concert with other diagnostic metrics of animal and facility evaluations, body condition scoring and ration evaluation to be fully useful in herd evaluations.

Seasonal changes in serum calcium, phosphorus, and vitamin D concentrations in llamas and alpacas.

OBJECTIVE: To evaluate the interaction of season and age on serum calcium, phosphorus, and vitamin D3 concentrations in llamas and alpacas. ANIMALS: 23 clinically normal llamas and 7 alpacas. PROCEDURES: Animals were assigned to 1 of the 3 following groups on the basis of age at the start of the study: adult (age, > or = 24 months; n = 8), yearling (> 12 but < 20 months; 5), and neonate (< 6 months; 17). Twelve serum samples were obtained at monthly intervals. Calcium, phosphorus, and vitamin D3 concentrations were measured, and the calcium-to-phosphorus concentration (Ca:P) ratio calculated. Effect of season and age on each of these variables was determined. RESULTS: Vitamin D3 concentrations varied significantly as a function of season; the highest and lowest concentrations were detected September through October and February through March, respectively. The seasonal decrease in vitamin D3 concentration was significantly greater in neonates and yearlings, compared with adults. Serum phosphorus concentration decreased as a function of age, with the most significant seasonal change detected in the neonate group. The Ca:P ratio in neonates varied between 1.1 and 1.3 except during winter months when it increased to > or = 2.0. CONCLUSIONS AND CLINICAL RELEVANCE: Mean vitamin D3 concentration varied by > 6 fold in neonatal and yearling llamas and alpacas and > 3 fold in adult animals as a function of season. These results support the hypothesis that seasonal alterations in vitamin D3 concentrations are a key factor in the development of hypophosphatemic rickets in llamas and alpacas.

Blood mineral and vitamin E concentrations in llamas.

OBJECTIVE: To establish reference values for blood concentrations of total calcium (Ca), inorganic phosphorus (P), iron (Fe), copper (Cu), zinc (Zn), selenium (Se), and vitamin E (Vit E) in clinically normal llamas. ANIMALS: 270 llamas ranging in age from < 1 month to > 15 years and grouped by age, sex, pregnancy status, and stage of gestation. Selected llamas were from 21 farms in Oregon, did not have previous health problems, and met specific health criteria on examination. PROCEDURE: Serum and blood samples were obtained and analyzed for concentrations of Ca, P, Fe, Cu, Se, Zn, and Vit E, and total iron binding capacity (TIBC) and percentage of transferrin saturation (% Sat). Mean differences by age, sex, pregnancy status, and stage of gestation, as well as all interactions, were compared to establish reference values. RESULTS: Mean values and reference ranges for most of the minerals and vitamins were similar to previously reported values. Male versus female differences were not identified for any measurements. Age was a significant variable for Ca, P, Fe, and Se concentrations, as well as Ca-to-P ratio and TIBC. Identified age-based effects were modeled by use of linear regression. Copper and Zn concentrations and % Sat did not differ as a function of age. Serum Vit E concentration was influenced by an age by sex interaction and stage of gestation. CONCLUSIONS: Age was found to be an important variable influencing many blood nutrient concentrations in healthy llamas. CLINICAL RELEVANCE: Clinical diagnosis of metabolic disease may be improved with use of age-based reference values, especially for neonates.

Glucose tolerance testing in llamas and alpacas.

OBJECTIVE: To determine blood glucose clearance in 2 species of New World camelids after IV challenge and to examine mechanisms of this clearance. ANIMALS: 5 adult female llamas and 5 adult gelded alpacas. PROCEDURE: After food was withheld for 12 hours, camelids received 0.5 g of glucose/kg of body weight by rapid IV infusion. Serum concentrations of glucose, nonesterified fatty acids, cortisol, and insulin, and plasma concentrations of lactate were determined before and 0, 1, 2, 3, 4, 5, 15, 30, 60, 90, 120, 180, and 240 minutes after infusion. Ratios of insulin to glucose and insulin to cortisol were calculated for each time point. RESULTS: Postinfusion glucose concentrations were significantly higher in llamas than alpacas for the first 15 minutes and remained significantly higher than baseline values in both species for 180 minutes. Lactate and cortisol concentrations did not change significantly; nonesterified fatty acid concentrations decreased in both species 30 minutes after infusion. Baseline insulin concentrations were < 6 microU/ml in both species and increased only to 10.1 +/- 0.7 microU/ml in llamas. Insulin concentrations did not change significantly in alpacas. CONCLUSIONS AND CLINICAL RELEVANCE: Llamas and alpacas clear glucose more slowly than other domestic species after challenge, mainly because of a weak insulin response and slow cellular uptake. This response may impair the assimilation of exogenous glucose as well as make llamas and alpacas prone to diabetes-like disorders when an abundance of endogenous or exogenous glucogenic agents are present.

Metabolic changes and induction of hepatic lipidosis during feed restriction in llamas.

OBJECTIVES: To determine whether feed restriction induces hepatic lipidosis (HL) in llamas and to evaluate the metabolic changes that develop during feed restriction. ANIMALS: 8 healthy adult female llamas. PROCEDURE: Llamas were fed grass hay at a rate of 0.25% of their body weight per day for 13 to 28 days. Llamas were monitored by use of clinical observation, serum biochemical analyses, and ultrasound-guided liver biopsies. RESULTS: All 8 llamas lost weight and mobilized fat. Five llamas developed HL, including 4 that were nursing crias. During the period of feed restriction, mean serum concentration of bile acids and activities of aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), and gamma-glutamyl transferase (GGT) were significantly higher in llamas that developed HL, compared with llamas that did not. Mean insulin-to-cortisol concentration ratios were lower in llamas with HL before and up to 7 days of feed restriction, compared with those that did not develop HL. CONCLUSIONS AND CLINICAL RELEVANCE: HL in llamas may be induced by severe feed restriction, particularly in the face of increased energy demand. Llamas with weight loss attributable to inadequate dietary intake may develop biochemical evidence of hepatopathy and HL. Increases in serum concentration of bile acids and activities of GGT, AST, and SDH may indicate the development of HL in llamas and identify affected animals for aggressive therapeutic intervention.

Pregnancy toxemia in a flock of sheep.

A high prevalence of metabolic disease was evident in a large flock of sheep early in the lambing season. Pregnancy toxemia and secondary hypocalcemia were diagnosed on the basis of history, physical examination findings, and results of serum biochemical analyses. To decrease costs to the owner, pooled serum samples were used to determine the metabolic health status of the flock. Ewes close to the time of lambing were found to be in severe negative energy balance, which resulted in excessive fat mobilization as well as clinical signs associated with pregnancy toxemia and hepatic lipidosis. By nutrient analysis, it was determined that the ewes had an inadequate amount of fermentable carbohydrates, which provide glucose to support the additional nutrition required during late gestation. The diet provided to sheep during late gestation should contain sufficient glucose precursors to maintain adequate glucose availability to maternal and fetal tissues. To minimize the physiologic decline in dry-matter intake during late gestation (which results in accentuation of negative energy balance), high-quality feed ingredients should be fed to ewes during this period.

Preputial foreign body in a bull.

A preputial foreign body caused severe preputial swelling and depression in a 4-year-old Shorthorn bull. Disruption of the preputial epithelium by the foreign body resulted in abscess formation lateral to the prepuce. A patent urethral fistula, probably a complication of prior fibropapilloma excisional surgery, was also detected on the distal portion of the glans penis. Foreign body removal, antimicrobial administration, and warm hydrotherapy resolved the swelling and abscess. Electroejaculation was used to extend the penis and to minimize preputial adhesions. Breeding soundness examinations were used to evaluate breeding potential.

Nutritional support for treatment of hepatic lipidosis in a llama.

A 3-year-old female llama that was 3 months into her first lactation and 10 weeks pregnant was evaluated for anorexia of 24 hours' duration. On physical examination, the llama was in lateral recumbency, bradycardic, tachypneic, and hyperthermic. Palpation per rectum confirmed the presence of a possible dry fecal mass in the spiral colon. A tissue biopsy specimen of the liver was obtained, and histologic examination revealed moderate diffuse lipid accumulation within the hepatocytes. Lactated Ringer's solution was administered for rehydration, and partial parenteral nutrition was then initiated. Hepatic lipidosis is a disease characterized by abnormal accumulation of lipid in the liver and is associated with high mortality in camelids. Anorexia associated with hepatic lipidosis promotes further lipid mobilization and fatty infiltration of the liver. Partial parenteral nutrition with enteral supplementation may be used to maintain adequate energy intake and minimize further lipid mobilization. The distinctive metabolism of camelids may require higher amino acid supplementation relative to nonprotein calories in parenteral solutions than those traditionally provided to other species. Treatment with insulin may be effective

Evaluation of vitamin D status of llamas and alpacas with hypophosphatemic rickets.

OBJECTIVE: To evaluate vitamin D concentrations in juvenile llamas and alpacas with hypophosphatemic rickets. DESIGN: Prospective cohort study. ANIMALS: 21 llamas (14 with rickets, 7 clinically normal) and 9 alpacas (6 with rickets, 3 clinically normal). PROCEDURES: Blood samples were collected at the time of diagnosis and prior to the initiation of treatment. Serum concentrations of calcium, inorganic phosphorus, and 25-hydroxycholecalciferol (vitamin D3) were determined on all samples. Comparisons were completed for disease status, age, sex, species, month of birth, and all interactions. RESULTS: Serum concentrations of phosphorus and vitamin D were lower in affected llamas and alpacas than in clinically normal llamas and alpacas, even when mean concentrations were adjusted for age differences. Species (llama or alpaca), sex, and age did not affect any of the metabolite concentrations within this study population. Month of birth influenced vitamin D concentrations and number of affected llamas and alpacas per month. The greatest number of affected llamas and alpacas was identified between January through March, suggesting a seasonal pattern to this syndrome. Treatment of affected llamas and alpacas with vitamin D resulted in increased concentrations of phosphorus and vitamin D. Serum phosphorus concentration was best predicted by 2 independent variables (serum vitamin D concentration and month of birth). CLINICAL IMPLICATIONS: We believe vitamin D deficiency is the primary cause of hypophosphatemic-rickets of growing camelids, and the observed hypophosphatemia is secondary to a primary deficiency of vitamin D. Appropriate treatment with vitamin D supplements can correct hypophosphatemia and vitamin D deficiency in camelids.

Hepatic lipidosis in llamas and alpacas: 31 cases (1991-1997).

OBJECTIVE: To identify factors associated with hepatic lipidosis (HL) in llamas and alpacas. DESIGN: Retrospective case series. ANIMALS: 30 llamas and 1 alpaca. PROCEDURES: Medical records were searched to identify llamas or alpacas in which a histologic diagnosis of HL was made. Information was retrieved on signalment, history, clinical and laboratory findings, and results of necropsy or examination of biopsy specimens. Data were analyzed using descriptive statistics and chi 2 analyses. RESULTS: Females were affected more often than males; however, the sex distribution was not different from that of the camelid population in the diagnostic laboratory's database. Fifty-four percent of the females were pregnant, and 46% were lactating. Most affected camelids were 6 to 10 years old. Anorexia and recent weight loss were common (51.6% of camelids). An infective agent was found in only one ilama, and toxins and mineral deficiencies were not identified. The most common abnormalities on serum biochemical analysis were a high concentration of bile acids, high activities of gamma-glutamyltransferase (GGT) and aspartate aminotransferase (AST), and hypoproteinemia. Concentrations of nonesterified fatty acids (NEFA) and beta-hydroxybutyrate (beta-HB) were high in those camelids in which these compounds were assayed. Twenty-nine camelids did not survive. CLINICAL IMPLICATIONS: Sick camelids should be considered at risk for developing HL, especially those with anorexia or the metabolic demands of pregnancy and lactation. Other stresses also appear to contribute. High concentrations of NEFA, beta-HB, and bile acids; high activities of GGT and AST; and hypoproteinemia may indicate that HL has developed.

Dry cow nutrition. The key to improving fresh cow performance.

Evidence supports the concept of the dry period being a critical component to lactation preparation rather than an insignificant rest period between lactations. Required nutrient amounts for the dry cow are the sum of maintenance, pregnancy, and reserve replenishment needs with additional requirements for growth during the first two pregnancies. Maintenance energy requirements can be dramatically increased by level of activity and adverse environmental conditions. A wide variety of feed ingredients can be successfully fed to dry cows as long as rations are appropriately formulated to meet energy, protein, mineral, and vitamin requirements. A early and close-up dry program best matches increasing pregnancy requirements and declining intake capacity with management capabilities. The early dry cow ration is formulated for high fiber/low energy density while the close-up ration contains higher energy density with less fiber. Both rations contain sufficient other nutrients based on determined intake. This two-group system provides maximal flexibility in managing for optimum body condition at calving. Environmental stresses and dramatic dietary changes should be minimized during the transition period from late gestation to lactation. A sound dry cow program results from integration of quality nutrition and cow management practices as described. A dry cow program that enacts these guidelines should result in reduced incidence of clinical mastitis, successfully complete pregnancy with a viable calf, maximize genetic potential for milk production, minimize incidence of health disorders, and allows cows to breed back within an economically optimum time interval. Overall, a sound dry cow program is a critical key to improved fresh cow performance.

Organic and inorganic selenium: II. Transfer efficiency from ewes to lambs.

Adequate Se transfer from ewes to lambs is important to prevent Se-deficiency diseases. To evaluate how different chemical forms of Se administered at comparative dosages to mature ewes affect Se status of their lambs, 240 ewes were divided into 8 treatment groups (n = 30 each) and drenched weekly (at an amount equal to their summed daily intake) with no-Se (controls); at recommended amounts (4.9 mg of Se/wk) with inorganic Na-selenite, inorganic Na-selenate, or organic Se-yeast; or at supranutritional amounts (14.7 and 24.5 mg of Se/wk) with Na-selenite or Se-yeast for 1 yr. Weekly drenching of Se was effective at increasing (P < 0.002) Se concentrations in ewe colostrum and milk at 30 d of lactation and in improving (P < 0.001) the Se status of lambs (whole-blood and serum-Se concentrations at birth, and skeletal-muscle Se concentrations at 14 d of age). Selenium concentrations in lacteal secretions were greater in ewes drenched with Se-yeast (colostrum: 374, 436, and 982 ng/mL at 4.9, 14.7, and 24.5 mg of Se/wk, respectively; milk: 26, 39, 64 ng/mL) compared with ewes drenched with Na-selenite (colostrum: 204, 334, 428 ng/mL; milk: 16, 21, 24 ng/mL), and were also greater (P < 0.001) in their lambs. Selenium concentrations continued to increase (P < 0.001) in lamb whole blood (558 and 695 ng/mL at 14.7 and 24.5 mg of Se/wk, respectively), serum (126, 183 ng/mL), and skeletal muscle (991, 1,696 ng/mL) with supranutritional concentrations of Se-yeast, whereas Se concentrations did not differ in whole blood (304, 332 ng/mL), serum (77, 85 ng/mL), or skeletal muscle (442, 482 ng/mg) of lambs from ewes drenched with 14.7 or 24.5 mg of Se/wk of Na-selenite. We conclude that weekly oral drenching of ewes during gestation and lactation with organic Se-yeast results in a more efficient transfer of Se (over a wide range of supplementation rates) from ewe to lamb than does inorganic Na-selenite.

Organic and inorganic selenium: I. Oral bioavailability in ewes.

Although the essentiality of dietary Se for sheep has been known for decades, the chemical source and Se dosage for optimal health remain unclear. In the United States, the Food and Drug Administration (FDA) regulates Se supplementation, regardless of the source of Se, at 0.3 mg of Se/kg of diet (as fed), which is equivalent to 0.7 mg of Se/d or 4.9 mg of Se/wk per sheep. The objectives of this study were to evaluate the effects of Se source (inorganic vs. organic) and supplementation rate (FDA vs. supranutritional rates of 14.7 and 24.5 mg of Se/wk) on whole-blood (WB) and serum-Se concentrations. Mature ewes (n = 240) were randomly assigned to 8 treatment groups (n = 30 each) based on Se supplementation rate (4.9, 14.7, and 24.5 mg of Se•wk(-1)•sheep(-1)) and source [Na-selenite, Na-selenate (4.9 mg/wk only), and organic Se-yeast] with a no-Se control group (0 mg of Se/wk). Treatment groups were balanced for healthy and footrot-affected ewes. For 1 yr, ewes were individually dosed once weekly with 0, 4.9, 14.7, or 24.5 mg of Se, quantities equivalent to their summed daily supplementation rates. Serum- and WB-Se concentrations were measured every 3 mo in all ewes; additionally, WB-Se concentrations were measured once monthly in one-half of the ewes receiving 0 or 4.9 mg of Se/wk. Ewes receiving no Se showed a 78.8 and 58.8% decrease (P < 0.001) in WB- (250 to 53 ng/mL) and serum- (97 to 40 ng/mL) Se concentrations, respectively, over the duration of the study. Whole-blood Se decreased primarily during pregnancy (-57%; 258 to 111 ng/mL) and again during peak lactation (-44%; 109 to 61 ng/mL; P < 0.001). At 4.9 mg of Se/wk, Se-yeast (364 ng/mL, final Se concentration) was more effective than Na-selenite (269 ng/mL) at increasing WB-Se concentrations (P < 0.001). Supranutritional Se-yeast dosages increased WB-Se concentrations in a dose-dependent manner (563 ng/mL, 14.7 mg of Se/wk; 748 ng/mL, 24.5 mg of Se/wk; P < 0.001), whereas WB-Se concentrations were not different for the Na-selenite groups (350 ng/mL, 14.7 mg of Se/wk; 363 ng/mL, 24.5 mg of Se/wk) or the 4.9 mg of Se/wk Se-yeast group (364 ng/mL). In summary, the dose range whereby Se supplementation increased blood Se concentrations was more limited for inorganic Na-selenite than for organic Se-yeast. The smallest rate (FDA-recommended quantity) of organic Se supplementation was equally effective as supranutritional rates of Na-selenite supplementation in increasing WB-Se concentrations, demonstrating the greater oral bioavailability of organic Se.

Effect of temperature on colostrometer readings for estimation of immunoglobulin concentration in bovine colostrum.

Effect of temperature on colostrometer readings for estimation of immunoglobulin concentration in bovine colostrum was investigated. Twenty-five colostrum samples were collected within 24 h postpartum from Holstein cows. Immunoglobulin concentration of colostrum was measured using a colostrometer through 5 degrees C increments from 0 to 40 degrees C. Two technicians measured independently a total of 225 samples. The agreement between technicians' readings was high (r = .98); thus, readings were averaged and used in regression analysis. A final regression model explained 92.5% of the total variation: corrected reading at 20 degrees C = uncorrected reading - 13.2 + .8 x temperature (degrees C). The regression equation was used to develop a conversion chart for practical field use.